TWI688151B - Non-aqueous lithium storage element - Google Patents

Abstract

The present invention provides a non-aqueous lithium electricity storage element, characterized in that it includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution. Among them, the positive electrode has a positive electrode current collector and a positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer, as described above The polymer has a RED value greater than 1 based on the Hansen solubility parameter of the non-aqueous electrolyte; the negative electrode has a negative electrode current collector and a negative electrode active material layer; the negative electrode active material layer contains absorbing and releasing lithium Ion anode active material; and non-aqueous electrolyte, which contains organic solvent and lithium salt electrolyte.

Description

Non-aqueous lithium storage element

The invention relates to a non-aqueous lithium electricity storage element.

In recent years, from the viewpoint of efficient use of energy with the goal of protecting the global environment and saving resources, power smoothing systems for wind power generation or late-night power storage systems, home-based distributed power storage systems based on solar power generation technology, and electric vehicles The power storage system used has received attention.

The first requirement for batteries used in these power storage systems is higher energy density. As a strong candidate for high energy density batteries that can respond to such demands, the industry is actively developing lithium ion batteries.

The second requirement is higher output characteristics. For example, for a combination of a high-efficiency engine and a power storage system (such as a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (such as a fuel cell electric vehicle), a high output discharge characteristic of the power storage system is required during acceleration.

At present, electric double-layer capacitors and nickel-metal hydride batteries have been developed as high-output power storage devices.

Electric double-layer capacitors using activated carbon as electrodes have an output characteristic of about 0.5 to 1 kW/L. This electric double-layer capacitor is also high in durability (cycle characteristics and high-temperature storage characteristics), and has been regarded as the most suitable device in the field requiring the above-mentioned high output. However, its energy density The degree is only about 1~5Wh/L. Therefore, the energy density needs to be further improved.

On the other hand, the nickel-metal hydride batteries currently used in hybrid vehicles have the same high output as electric double-layer capacitors and have an energy density of about 160Wh/L. However, in order to further improve its energy density and output and improve durability (especially stability at high temperatures), the industry is actively conducting research.

In addition, lithium-ion batteries are also being studied for higher output. For example, the development of lithium-ion batteries with a high output of more than 3kW/L at a depth of discharge (a value indicating how much of the discharge capacity of the storage element is released) at 50%. However, its energy density is 100 Wh/L or less, which presents a design that forcibly suppresses the high energy density that is the biggest feature of lithium ion batteries. Its durability (cycle characteristics and high-temperature storage characteristics) is inferior to electric double layer capacitors. Therefore, in order to make it practically durable, it needs to be used in a range where the depth of discharge is less than 0 to 100%. The actual usable capacity has become smaller, so the industry is actively conducting research to further improve durability.

As described above, the industry strongly seeks to put the practical use of power storage devices that combine high energy density, high output characteristics, and durability. However, the above-mentioned existing power storage devices each have advantages and disadvantages. Therefore, a novel power storage element that fully satisfies these technical requirements is sought. As a powerful candidate, storage elements called lithium-ion capacitors are receiving attention, and their development is prevalent in the industry.

Lithium-ion capacitors are one type of electricity storage elements (non-aqueous lithium electricity storage elements) containing non-aqueous electrolytes containing lithium salts, and the same adsorption and desorption as electric double-layer capacitors are carried out in the positive electrode under conditions of about 3 V or more The non-Faraday reaction with anions performs the Faraday reaction of absorbing and releasing lithium ions in the negative electrode in the negative electrode to charge and discharge the storage element.

Summarizing the above-mentioned electrode materials and their characteristics, in the case of using activated carbon and other materials for the electrode, charging and discharging by adsorption and desorption of ions on the surface of the activated carbon (illegal Faraday reaction), although high output and high durability are achieved, The energy density will become lower (for example, double). When an oxide or carbon material is used as an electrode and the Faraday reaction is used to charge and discharge, although the energy density will be higher (for example, it is set to 10 times the illegal Faraday reaction using activated carbon), but the durability and output characteristics There is a problem.

As a combination of these electrode materials, electric double-layer capacitors are characterized by using activated carbon (energy density is doubled) for the positive and negative electrodes, both positive and negative electrodes are charged and discharged by the non-Faraday reaction, and have the advantages of high output and High durability but low energy density (1x positive electrode × 1x negative electrode = 1).

Lithium ion secondary batteries are characterized by using lithium transition metal oxides (energy density 10 times) for the positive electrode, and carbon materials (energy density 10 times) for the negative electrode, both positive and negative electrodes are charged and discharged by Faraday reaction, Although it has a high energy density (10 times positive electrode×10 times negative electrode=100), it has problems in output characteristics and durability. In order to meet the high durability requirements of hybrid vehicles, etc., the depth of discharge must be limited. For lithium ion secondary batteries, only 10 to 50% of their energy can be used.

Lithium-ion capacitors use activated carbon (energy density 1 times) for the positive electrode, and carbon materials (energy density 10 times) for the negative electrode. The positive electrode is charged and discharged by non-Faraday reaction and the negative electrode by Faraday reaction. Features are novel asymmetric capacitors that have the characteristics of both electric double layer capacitors and lithium ion secondary batteries. Moreover, it has the characteristics of high output and high durability, and high energy density (positive electrode 1 times×negative electrode 10 times=10), and there is no need to limit the depth of discharge like lithium ion secondary batteries.

Under this background, Patent Literature 1 proposes a lithium ion secondary battery, which enables It uses a positive electrode containing lithium carbonate in the positive electrode, and has a current breaking mechanism that operates according to the increase in the internal pressure of the battery. Patent Document 2 proposes a lithium ion secondary battery that uses a lithium composite oxide such as lithium manganese acid for a positive electrode, and suppresses elution of manganese by including lithium carbonate in the positive electrode. In addition, Patent Document 3 proposes a non-aqueous lithium power storage device that suppresses excessive decomposition of remaining lithium compounds and suppresses gas generation at high voltage by controlling the coverage rate of the fluorine compound coated on the surface of the lithium compound in the positive electrode.

On the other hand, Patent Document 4 discloses a lithium-ion capacitor that uses a lithium salt electrolyte having an imide structure and a binder containing a polymer that inhibits the solubility of the electrolyte, and can be used in a high-temperature environment of 85°C. The capacity is maintained, and the increase in internal resistance is small.

Patent Document 5 discloses a positive electrode precursor, which can promote the decomposition of an alkali metal compound contained in the positive electrode precursor, and can pre-dope the negative electrode in a short time, which is used in a high-capacity non-aqueous hybrid capacitor.

Patent Document 6 discloses a positive electrode composition for lithium secondary batteries, the positive electrode active material is made of a lithium transition metal composite oxide, and the viscosity change rate after the homogenization treatment for 30 minutes and 2 hours is smaller than the viscosity change rate indicated And stable.

Patent Document 7 discloses a method for manufacturing a high-output lithium-ion battery, which uses an aluminum current collector.

Patent Document 8 proposes a technical content that ensures the electronic conductivity among the plurality of positive electrode active materials by controlling the average particle diameter of the lithium compound contained in the positive electrode and the average particle diameter of the plurality of positive electrode active materials, and Increased output and high energy density of water-based lithium storage elements.

In addition, in this specification, the mesopore volume is calculated by the BJH method, and the micropore volume is calculated by the MP method, and the BJH method is advocated by Non-Patent Document 1, and the MP method refers to the use of "t-drawing method" ( Non-patent 2) The method of obtaining the micropore volume, micropore area, and micropore distribution is disclosed in Non-Patent Document 3.

【Prior Technical Literature】 【Patent Literature】

[Patent Document 1] Japanese Patent Laid-Open No. 4-328278

[Patent Document 2] Japanese Patent Laid-Open No. 2001-167767

[Patent Document 3] International Publication No. 2017/126689

[Patent Document 4] Japanese Patent Application Publication No. 2017-17299

[Patent Document 5] International Publication No. 2017/126687

[Patent Document 6] Japanese Patent Laid-Open No. 10-64518

[Patent Document 7] Japanese Patent Laid-Open No. 2016-38962

[Patent Document 8] International Publication No. 2017/126693

【Non-patent literature】

[Non-Patent Document 1] E.P. Barrett, L.G. Joyner and P. Halenda, J. Am. Chem. Soc., 73,373 (1951)

[Non-Patent Document 2] B.C. Lippens, J.H. de Boer, J. Catalysis, 4319 (1965)

[Non-Patent Document 3] R.S. Mikhail, S. Brunauer, E.E. Bodor, J. Colloid Interface Sci., 26, 45 (1968)

However, the above-mentioned Patent Documents 1 to 4 and 8 do not consider the corrosion resistance of the positive electrode current collector in a high-voltage use environment while suppressing the corrosion of the positive electrode current collector under the high-temperature durability above 85° C. Disconnection of current collector, etc.

In addition, the lithium-ion capacitor described in Patent Document 4 has a problem that the volume of the power storage element becomes large due to the low energy density, and there is a problem in the application of space-restricted automotive applications. In addition, since the separator shrinks under the condition of high temperature (for example, 85° C. or higher), the holes through which ions pass are likely to be blocked, so there is a concern that the resistance will increase in high-temperature storage.

In addition, the positive electrode coating solution containing carbon materials and alkali metal compounds in the dispersion solvent has the following problems due to the change of the thixotropic viscosity reducing viscosity: the peel strength of the positive electrode precursor is reduced, and the drops during electrode coating In the liquid and/or pre-doping step, the decomposition of the alkali metal compound generates gas, which causes the cathode active material layer to fall off. However, the conventional positive electrode coating liquids described in Patent Documents 4 to 6 do not take into account these problems caused by changes in thixotropic viscosity reduction, nor do they consider positive electrodes with high-temperature durability of 85°C or higher Precursor.

In addition, the technologies described in Patent Documents 4, 5, and 7 do not consider the suppression of the shedding of the positive electrode active material caused by the gas generation in the pre-doping step, and the resulting micro-short circuit, and have a temperature of 85°C or higher High temperature and durable lithium ion capacitors.

The first problem to be solved by the present invention is to provide a non-aqueous lithium power storage device having high capacity, excellent input and output characteristics, and high durability for storage at a high temperature of 85°C or higher. The second subject is to provide a positive electrode coating liquid and a positive electrode precursor for a positive electrode precursor, wherein the positive electrode precursor can be used to pre-process the negative electrode in a short time by promoting the decomposition of an alkali metal compound Doping, and can suppress the shedding of the positive electrode active material during pre-doping, and has high temperature durability above 85 ℃.

The inventors of the present invention conducted intensive research to solve the above-mentioned problems, and repeatedly conducted experiments.

As a result, it was found that a non-aqueous lithium electricity storage element provided with a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution; and at the positive electrode, containing a positive electrode active material, a lithium compound other than the positive electrode active material, and containing insoluble or Adhesives for polymers that are difficult to dissolve in non-aqueous electrolytes; separators show a specific thermal shrinkage; non-aqueous electrolytes have a high capacity and excellent output when they contain a lithium salt electrolyte with an imide structure Characteristics and high durability for storage at high temperatures.

In addition, the present inventors found that by making the positive electrode active material layer of the positive electrode precursor contain a lithium compound other than the positive electrode active material, the solubility of the binder to the non-aqueous electrolyte is suppressed, and the non-aqueous electrolyte is controlled at a high voltage The aluminum foil is corrosion-resistant and can obtain a non-aqueous lithium storage element with high input and output and excellent high temperature durability.

That is, one aspect of the present invention is as described below.

[1] A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; the positive electrode is characterized by having a positive electrode current collector and a surface disposed on the positive electrode current collector Or a positive electrode active material layer on both sides; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer, before The polymer has a RED value greater than 1 based on the Hansen solubility parameter of the non-aqueous electrolyte; the negative electrode has a negative electrode collector and negative electrode activity disposed on one or both sides of the negative electrode collector The material layer; the negative electrode active material layer contains a negative electrode active material capable of absorbing and releasing lithium ions; and the non-aqueous electrolyte solution contains an organic solvent and a lithium salt electrolyte.

[2] The non-aqueous lithium electricity storage element according to item 1, wherein the polymer includes an alkali metal salt of acrylic acid, methacrylic acid, acrylate, methacrylate, acrylic acid, and methacrylic acid A polymer formed by monomers of any one or more of alkali metal salts.

[3] The non-aqueous lithium electricity storage element according to item 1 or 2, wherein the air permeability P after the separator is kept at 120°C for 1 hour is 5 seconds/100 mL or more and 300 seconds/100 mL or less; and The withstand voltage of the separator is 0.4kV or more; and for the aforementioned separator, when the length of the original separator is set to L1 and the length of the separator after holding at 120°C for 1 hour is set to L2, according to (L1-L2)/ The shrinkage calculated by L1 is 0.1 or less.

[4] The non-aqueous lithium electricity storage element according to any one of items 1 to 3, wherein the separator includes at least one selected from the group consisting of polyolefin, cellulose, and polyaramide resin .

[5] The non-aqueous lithium electricity storage device according to any one of items 1 to 4, wherein the lithium compound other than the positive electrode active material is selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide At least one Species.

[6] The non-aqueous lithium electricity storage device according to any one of items 1 to 5, wherein the positive electrode active material contains activated carbon.

[7] The non-aqueous lithium power storage device according to any one of items 1 to 6, wherein the positive electrode active material includes a lithium transition metal oxide, and the lithium transition metal oxide is represented by the following formula Compound: Li _x Ni _a Co _b Al _(1-ab) O ₂ {where x satisfies 0≦x≦1, and a and b satisfy 0.2<a<0.97 and 0.2<b<0.97}, Li _x Ni _c Co _d Mn _(1-cd) O ₂ {where x satisfies 0≦x≦1, and c and d satisfy 0.2<c<0.97 and 0.2<d<0.97}, Li _x CoO ₂ {where x satisfies 0≦x≦1}, Li _x Mn ₂ O ₄ {where x satisfies 0≦x≦1}, Li _x FePO ₄ {where x satisfies 0≦x≦1}, Li _x MnPO ₄ {where , X satisfies 0≦x≦1}, or Li _z V ₂ (PO ₄ ) ₃ {where, z satisfies 0≦z≦3}.

[8] A non-aqueous lithium electricity storage element, comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; characterized in that the positive electrode has a positive electrode current collector and is disposed on one surface of the positive electrode current collector Or the positive electrode active material layer on both sides; the aforementioned positive electrode active material layer contains the positive electrode active material, the aforementioned positive electrode Lithium compounds other than extremely active materials, and binders; the binders contain a polymer, the polymer has a RED value based on the Hansen solubility parameter of the non-aqueous electrolyte greater than 1; the negative electrode has a negative electrode set The electric body and the negative electrode active material layer disposed on one or both sides of the negative electrode current collector; the negative electrode active material layer contains a negative electrode active material capable of absorbing and releasing lithium ions; the withstand voltage of the separator is 0.8 kV or more; and for the aforementioned separator, when the original separator length is set to L1, and the separator length after holding at 120°C for 1 hour is set to L2, the shrinkage ratio calculated from (L1-L2)/L1 is 0.1 The following; the non-aqueous electrolyte contains an organic solvent and a lithium salt electrolyte; the non-aqueous lithium storage element has an initial internal resistance of Ra (Ω) at a cell voltage of 4.1 V and an ambient temperature of 25° C. ), when the internal resistance of the cell voltage 4.1V and the ambient temperature 25°C after storing the cell voltage 4.1V and the ambient temperature 85°C for 1000 hours is Rb (Ω), Rb/Ra is 3.0 or less.

[9] A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; the positive electrode is characterized by having a positive electrode current collector and a surface disposed on the positive electrode current collector Or a positive electrode active material layer on both sides; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer, the polymer is based on the The RED value of the Hansen solubility parameter of the non-aqueous electrolyte is greater than 1; the negative electrode has a negative electrode current collector and a negative electrode active material layer disposed on one or both sides of the negative electrode current collector; the negative electrode active material layer, It contains ions that can absorb and release lithium ions Negative electrode active material; the air permeability P after the separator is kept at 120°C for 1 hour is 5 seconds/100 mL or more and 300 seconds/100 mL or less; and the separator has the original separator length L1 and will be 120 When the separator length after being kept at ℃ for 1 hour is set to L2, the shrinkage ratio calculated from (L1-L2)/L1 is 0.1 or less; the non-aqueous electrolyte solution contains an organic solvent and a lithium salt electrolyte; the non-aqueous system For lithium electricity storage elements, when the internal resistance of the discharge at a cell voltage of 4V and an ambient temperature of -30°C is set to Rd(Ω), and the internal resistance at an ambient temperature of 25°C is set to Ra(Ω), Rd/Ra is 15 or less .

[10] The non-aqueous lithium electricity storage element according to any one of items 1 to 9, wherein the non-aqueous electrolyte solution is obtained by using aluminum foil as a working electrode and using lithium metal as a counter electrode and a reference electrode, respectively In the cyclic voltammogram, the maximum reaction current value in the voltage range of 3.8 V (vs. Li/Li ⁺ ) or more and 4.8 V (vs. Li/Li ⁺ ) or less is 0.010 mA/cm ² or less relative to the area of the aforementioned aluminum foil .

[11] The non-aqueous lithium electricity storage device according to any one of items 1 to 10, wherein the non-aqueous electrolyte solution contains a lithium salt having an amide imide structure.

[12] The non-aqueous lithium electricity storage device according to any one of items 1 to 11, wherein the non-aqueous electrolyte contains groups selected from LiPF ₆ , LiBF ₄ , and LiF ₂ BC ₂ O ₄ At least one of them.

[13] The non-aqueous lithium electricity storage device according to any one of items 1 to 12, wherein the non-aqueous electrolyte solution contains a non-aqueous solvent containing a cyclic carbonate and a chain carbonate.

[14] The non-aqueous lithium electricity storage device according to any one of items 1 to 13, wherein the non-aqueous electrolyte contains a non-aqueous solvent, and the non-aqueous solvent does not contain dimethyl carbonate but contains Ethylene carbonate and propylene carbonate contain more of the aforementioned ethyl carbonate than the aforementioned propylene carbonate.

[15] The non-aqueous lithium electricity storage device according to any one of items 1 to 14, wherein the non-aqueous electrolyte solution contains a non-cyclic fluorine-containing ether, a cyclic fluorine-containing carbonate, and a ring At least one of the group of fluorine-containing phosphazene.

[16] The non-aqueous lithium electricity storage device according to any one of items 1 to 15, wherein the negative electrode active material layer further contains a binder containing polyacrylic acid.

[17] A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing a lithium salt; characterized in that the positive electrode has a positive electrode current collector and is disposed on the positive electrode collector The positive electrode active material layer on one or both sides of the electric body; the positive electrode active material layer contains the positive electrode active material and the binder; the positive electrode active material contains the carbon material; the binder contains a polymer and the polymerization The RED value based on the Hansen solubility parameter of the non-aqueous electrolyte is greater than 1; and the positive electrode includes a lithium compound other than the positive electrode active material; the negative electrode has a negative electrode current collector and is disposed on the negative electrode collector The negative electrode active material layer on one or both sides of the electric body; the negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions; for the non-aqueous electrolyte solution, aluminum foil is used as the working electrode, and lithium metal is used respectively When the cyclic voltammogram is obtained as the counter electrode and the reference electrode, the maximum reaction current value in the voltage range of 3.8 V (vs. Li/Li ⁺ ) or more and 4.8 V (vs. Li/Li ⁺ ) or less, relative to the Area is 0.010mA/cm ² or less; for the aforementioned non-aqueous lithium storage element, the initial internal resistance at the cell voltage of 3.8V is Ra (Ω), the electrostatic capacity is F (F), and the electric energy is E (Wh) , And the volume of the non-aqueous lithium storage element is set to V (L), at the same time satisfy the following (a) and (b): (a) Ra and F product Ra. F series is 0.3 or more and 3.0 or less, and (b) E/V series is 15 or more and 80 or less.

[18] A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing a lithium salt; characterized in that the positive electrode has a positive electrode current collector and is disposed on the positive electrode collector The positive electrode active material layer on one or both sides of the electric body; the positive electrode active material layer contains the positive electrode active material and the binder; the positive electrode active material contains the carbon material; the binder contains a polymer and the polymerization The RED value based on the Hansen solubility parameter of the non-aqueous electrolyte is greater than 1; and the positive electrode includes a lithium compound other than the positive electrode active material; the negative electrode has a negative electrode current collector and is disposed on the negative electrode collector The negative electrode active material layer on one or both sides of the electric body; the negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions; for the non-aqueous electrolyte solution, use aluminum foil as the working electrode, and use lithium respectively When the metal is used as the counter electrode and the reference electrode to obtain a cyclic voltammogram, the maximum reaction current value in the voltage range of 3.8 V (vs. Li/Li ⁺ ) or more and 4.8 V (vs. Li/Li ⁺ ) or less, relative to the aforementioned aluminum foil The area of 0.010mA/cm ² or less; the aforementioned non-aqueous lithium storage element, the initial internal resistance at the cell voltage of 3.8V is set to Ra (Ω), will be stored at a cell voltage of 4V and ambient temperature of 85 ℃ for 2 months When the internal resistance at 25° C. is Rb (Ω), the following (c) is satisfied: (c) Rb/Ra is 3.0 or less.

[19] An electricity storage module; an electric power regeneration auxiliary system; an electric load leveling system; an uninterruptible power supply system; a non-contact power supply system; an energy harvesting system; a solar power storage system; an electric steering system; An emergency power supply system; an in-wheel motor system; an idling flameout system; a vehicle; a fast charging system; or a smart grid system characterized by including a non-aqueous system as described in any one of items 1 to 18 Lithium storage element.

[20] A power storage system characterized by connecting a non-aqueous lithium power storage element as described in any one of items 1 to 18 in series or parallel to a lead battery, a nickel-metal hydride battery, a lithium ion secondary battery, or a fuel cell .

[21] The vehicle according to item 19, wherein the vehicle is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric vehicle.

[22] A positive electrode coating liquid comprising a positive electrode active material, an alkali metal compound, and a solid component of a binder in a dispersion solvent, characterized in that the positive electrode active material contains Carbon material; the binder contains a polyacrylic acid compound; and the thixotropic index value of the positive electrode coating solution is set to TI ₁ , and the thixotropic index value after standing for 24 hours after measuring TI ₁ is set to TI ₂ In this case, the TI ₂ /TI ₁ system is 0.50 or more and 1.20 or less.

[23] The positive electrode coating liquid according to item 22, wherein, when the viscosity of the positive electrode coating liquid is ηb ₁ and the viscosity after measuring ηb ₁ and standing for 24 hours is ηb ₂ , ηb ₂ /ηb ₁ is 0.40 or more and 1.30 or less.

[24] The positive electrode coating liquid according to item 22 or 23, wherein the carbon material is activated carbon.

}。 [25] The positive electrode coating liquid according to any one of items 22 to 24, wherein the positive electrode active material further includes a lithium transition metal oxide represented by the following formula: Li _x Ni _a Co _b Al _{(1 -ab)} O ₂ {where x satisfies 0≦x≦1, and a and b satisfy 0.2<a<0.97 and 0.2<b<0.97}, Li _x Ni _c Co _d Mn _(1-cd) O ₂ {where x satisfies 0≦x≦1, and c and d satisfy 0.2<c<0.97 and 0.2<d<0.97}, Li _x CoO ₂ {where x satisfies 0≦x≦1}, Li _x Mn ₂ O ₄ {where x satisfies 0≦x≦1}, Li _x FePO ₄ {where x satisfies 0≦x≦1}, Li _x MnPO ₄ {where x satisfies 0≦x≦ 1}, or Li _z V ₂ (PO ₄ ) ₃ {where, z satisfies 0≦z≦3

}.

[26] The positive electrode coating liquid according to any one of items 22 to 25, wherein the solid content ratio is 15% or more and 60% or less.

[27] The positive electrode coating liquid according to any one of items 22 to 26, wherein the alkali metal compound is at least one selected from the group consisting of lithium carbonate, sodium carbonate, and potassium carbonate.

[28] The positive electrode coating liquid according to any one of items 22 to 27, wherein the dispersion solvent is water.

[29] The positive electrode coating liquid according to item 28, wherein the positive electrode coating liquid further contains a pH adjusting agent.

[30] The positive electrode coating solution according to item 28 or 29, wherein the pH value is 6.0 or more and 13.0 or less.

[31] The positive electrode coating solution according to any one of items 22 to 30, wherein the binder further comprises a PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), poly At least one of the group consisting of amide imide, latex, styrene-butadiene copolymer, fluororubber, and acrylic polymer.

[32] The positive electrode coating liquid according to any one of items 22 to 31, wherein the positive electrode coating liquid further comprises a carboxymethyl cellulose, methyl cellulose, ethyl cellulose, Cellulose Acetate Phthalate, Hydroxymethoyl Cellulose, Hydroxypropyl Methyl Cellulose, Hydroxyethyl Methyl Cellulose, Hydroxypropyl Methyl Cellulose Phthalate, Polyvinyl Hydropyrrolidone, Polyethylene A dispersant for at least one of the group consisting of alcohol and polyvinyl acetal.

[33] The positive electrode coating liquid according to any one of items 22 to 32, wherein the carbon material is activated carbon, and the activated carbon is derived from a diameter calculated from the BJH method of 20 Å or more and 500 Å or less When the amount of pores in the pores is V ₁ (cc/g), and the amount of micropores derived from pores with a diameter less than 20Å calculated by the MP method is V ₂ (cc/g), 0.3<V ₁ ≦ 0.8, and 0.5 ≦ V ₂ ≦ 1.0, further, the specific surface area determined based 1,500m ² / g or more 3,000m ² / g or less according to the BET method.

[34] A method of manufacturing a positive electrode precursor, characterized by using the positive electrode coating liquid described in any one of items 22 to 33.

[35] A positive electrode precursor, which is a positive electrode precursor manufactured using the positive electrode coating liquid as described in any one of items 22 to 33, characterized in that the positive electrode precursor includes a current collector and A positive electrode active material layer disposed on the current collector; the positive electrode active material layer includes a positive electrode active material, an alkali metal compound, and a binder; the positive electrode active material includes a carbon material; and the binder includes a polymer Acrylic compound; and the peel strength of the positive electrode active material layer is 0.020N/cm or more and 3.00N/cm or less.

[36] The positive electrode precursor according to item 35, wherein the current collector is a non-porous aluminum foil.

[37] The positive electrode precursor according to item 35 or 36, wherein an anchor layer is further provided between the current collector and the positive electrode active material layer.

[38] The positive electrode precursor according to any one of items 35 to 37, wherein the peel strength of the positive electrode active material layer after being immersed in water at 25°C for 24 hours and dried is 0.020N/cm or more 3.00N/ cm below.

[39] The positive electrode precursor according to any one of items 35 to 38, wherein the moisture contained in the positive electrode active material layer is 0.1% by mass or more and 10% by mass or less.

[40] The positive electrode precursor according to any one of items 35 to 39, wherein the positive electrode active material layer is applied and/or intermittently applied to the current collector in a plurality of layers.

[41] The positive electrode precursor according to any one of items 35 to 40, wherein the positive electrode active material layers are provided on both sides of the current collector.

[42] A method of manufacturing an electrode body characterized by using a positive electrode precursor manufactured by the method described in item 34.

[43] A method of manufacturing a non-aqueous lithium electricity storage element, characterized in that it includes a step of including an external body with an electrode body manufactured by the method described in item 42.

[44] A non-aqueous lithium electricity storage element characterized by comprising the positive electrode precursor as described in any one of items 35 to 41.

[45] An electricity storage module; an electric power regeneration auxiliary system; an electric load leveling system; an uninterruptible power supply system; a non-contact power supply system; an energy harvesting system; a solar power storage system; an electric power steering system; an emergency power supply A system; an in-wheel motor system; an idling flameout system; a vehicle; a fast charging system; or a smart grid system characterized by including a non-aqueous lithium storage element as described in item 44.

[46] An electricity storage system characterized by connecting the non-aqueous lithium electricity storage element described in item 44 in series or parallel to a lead battery, nickel-metal hydride battery, lithium ion secondary battery or fuel cell.

[47] The vehicle according to item 45, wherein the vehicle is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric vehicle.

In addition, other aspects of the invention are as follows.

[48] A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; characterized in that the positive electrode has a positive electrode current collector and one or both sides of the positive electrode current collector On the positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer, the polymer is based on the non-aqueous system The RED value of the Hansen solubility parameter of the electrolyte is greater than 1; the negative electrode has a negative electrode current collector, a negative electrode active material layer on one or both sides of the negative electrode current collector; the negative electrode active material layer contains an absorbable And negative active materials that release lithium ions; For the aforementioned separator, when the length of the original separator is set to L1, and the length of the separator after holding at 120°C for 1 hour is set to L2, the shrinkage ratio calculated from (L1-L2)/L1 is 0.1 or less; The aqueous electrolyte includes an organic solvent and a lithium salt electrolyte having an imidate structure.

[49] A non-aqueous lithium electricity storage element, comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; characterized in that the positive electrode has a positive electrode current collector and one or both sides of the positive electrode current collector On the positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer, the polymer is based on the non-aqueous system The RED value of the Hansen solubility parameter of the electrolyte is greater than 1; the negative electrode has a negative electrode current collector and a negative electrode active material layer on one or both sides of the negative electrode current collector; the negative electrode active material layer contains an absorbable The negative electrode active material that stores and releases lithium ions; the aforementioned separator, when the original separator length is set to L1, and the separator length after holding at 120°C for 1 hour is set to L2, according to (L1-L2)/L1 The calculated shrinkage rate is 0.1 or less; the aforementioned electrolyte contains an organic solvent and a lithium salt electrolyte having an amide imide structure; the aforementioned non-aqueous lithium electricity storage element has an initial internal temperature of 3.8V and an ambient temperature of 25°C The resistance is set to Ra (Ω). When the cell voltage is stored at 4.0 V and the ambient temperature is 85 °C for 1000 hours, the internal resistance at the cell voltage of 3.8 V and ambient temperature 25 °C is set to Rd (Ω). Rd/Ra is 3.0 the following.

[50] A positive electrode precursor, characterized by having a current collector and a positive electrode disposed on the current collector Active material layer; the positive electrode active material layer includes a positive electrode active material, an alkali metal compound, and a binder; the positive electrode active material includes a carbon material; the binder includes a polyacrylic acid compound; and the peeling of the positive electrode active material layer The strength is 0.020N/cm or more and 3.00N/cm or less.

[51] A non-aqueous lithium electricity storage element formed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing a lithium salt, characterized in that the positive electrode has a positive electrode current collector and the positive electrode current collector The positive electrode active material layer on one or both sides of the electric body; the positive electrode active material layer contains a positive electrode active material and a binder; the positive electrode active material contains a carbon material; the binder contains a polymer, the polymer The RED value based on the Hansen solubility parameter of the non-aqueous electrolyte is greater than 1; and the positive electrode includes a lithium compound other than the positive electrode active material; the negative electrode has a negative electrode current collector and one side of the negative electrode current collector Or the negative electrode active material layer on both sides; the negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions; for the non-aqueous electrolyte solution, aluminum foil is used as a working electrode, and lithium metal is used as a counter electrode, respectively When the cyclic voltammogram is obtained by referring to the electrode, the maximum reaction current value in the voltage range of 3.8 V (vs. Li/Li ⁺ ) or more and 4.8 V (vs. Li/Li ⁺ ) or less is 0.010 mA relative to the area of the aluminum foil. /cm ² or less.

According to the present invention, it is possible to provide a non-aqueous lithium electricity storage element having high capacity, excellent output characteristics, and high durability to storage at a high temperature of 85°C or higher.

In addition, according to the present invention, a positive electrode precursor can be provided, which can pre-do a negative electrode in a short time by promoting decomposition of an alkali metal compound, and can suppress the shedding of a positive electrode active material during pre-doping And it has high temperature durability above 85℃; and can provide a positive electrode coating liquid for positive electrode precursor.

In the following, a detailed description is given to illustrate an embodiment of the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited to this embodiment. In the specification of this case, the upper and lower limits of each numerical range can be arbitrarily combined.

"Non-aqueous Lithium Storage Element"

The non-aqueous lithium power storage element generally has a positive electrode, a negative electrode, a separator, and an electrolyte as main components. As the electrolytic solution, an organic solvent (hereinafter referred to as "non-aqueous electrolytic solution") containing an electrolyte in which an alkali metal salt is dissolved (when the alkali metal is lithium is a lithium salt) is used.

The non-aqueous lithium storage element of this embodiment is provided with a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; the positive electrode has a positive electrode current collector and positive electrode activity on one or both surfaces of the positive electrode current collector Material layer; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer based on the non-aqueous electrolyte The RED value of the Sen solubility parameter is greater than 1; the negative electrode has a negative electrode current collector and a negative electrode active material layer on one or both sides of the negative electrode current collector; the negative electrode active material layer contains lithium that can absorb and release lithium Ionic negative active material; and The non-aqueous electrolyte solution includes an organic solvent and a lithium salt electrolyte.

For the above non-aqueous electrolyte, using aluminum foil as the working electrode and lithium metal as the counter electrode and reference electrode respectively to obtain a cyclic voltammogram, 3.8V (vs.Li/Li ⁺ ) or more 4.8V (vs.Li/ Li ⁺ ) The maximum reaction current value in the voltage range below is 0.010 mA/cm ² or less with respect to the area of the aluminum foil.

<positive electrode>

The positive electrode precursor of this embodiment has a positive electrode current collector and a positive electrode active material layer disposed thereon. In more detail, the positive electrode active material layer is provided on one or both surfaces and includes a positive electrode Active substance. The characteristics of the positive electrode active material layer of this embodiment include a carbon material, an alkali metal compound (when the alkali metal is lithium, called a lithium compound), and a binder. As will be described later, in this embodiment, it is preferable that the negative electrode is pre-doped with alkali metal ions during the assembly step of the storage element. This pre-doping method is preferably to apply a voltage between the positive electrode precursor and the negative electrode after the storage element is assembled using the positive electrode precursor containing the alkali metal compound, the negative electrode, the separator, the exterior body, and the non-aqueous electrolyte. The alkali metal compound may be contained in the positive electrode precursor in any form. For example, the alkali metal compound may exist between the positive electrode current collector and the positive electrode active material layer, or may exist on the surface of the positive electrode active material layer. The alkali metal compound is preferably a positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor. In this aspect, as the negative electrode is pre-doped with alkali metal ions, holes are formed in the positive electrode active material layer, and the effective area of the positive electrode active material layer increases.

In this specification, the positive electrode before the alkali metal doping step is defined as "positive electrode precursor", and the positive electrode after the alkali metal doping step is defined as "positive electrode". The positive electrode coating liquid is not only a known type of coating liquid, but also a type including a known suspension, dispersion, emulsion, composition or mixture. The positive electrode coating liquid of this embodiment is sometimes simply referred to as slurry, coating liquid, or the like.

In addition, in the specification of the present invention, when the alkali metal is lithium, the "alkali metal compound" is renamed as "lithium compound", and the "alkali metal doping step" is renamed as "lithium doping step". "Metal" was renamed "Lithium".

[Cathode Coating Liquid]

The positive electrode coating liquid of the present embodiment contains a solid component containing a carbon material, an alkali metal compound, and a polyacrylic acid compound in a dispersion solvent. In addition to these, the positive electrode coating liquid may contain optional components such as a conductive material, a dispersing agent, and a pH adjusting agent, if necessary.

[Positive active material layer]

The positive electrode active material layer included in the positive electrode contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder. The positive electrode active material preferably contains a carbon material, and may further contain a lithium transition metal oxide as the positive electrode active material. In addition to the positive electrode active material, the binder, and the lithium compound, the positive electrode active material layer may contain optional components such as a conductive filler, a dispersion stabilizer, and a pH adjusting agent, if necessary.

In addition, the positive electrode active material layer preferably contains an alkali metal compound in the positive electrode active material layer of the positive electrode precursor or on the surface of the positive electrode active material layer.

[Positive active material]

The positive electrode active material contains a carbon material, and may further contain a lithium transition metal oxide. The carbon material is preferably exemplified by activated carbon, nano carbon tubes, conductive polymers, and porous carbon materials, more preferably activated carbon. As the positive electrode active material, one carbon material may be used alone, or two or more carbon materials may be mixed and used.

For the lithium transition metal oxide, known materials used for lithium ion batteries can be used. It is also possible to mix and use more than one lithium transition metal oxide for the positive electrode active material.

(Activated carbon)

The type of activated carbon used as the positive electrode active material and its raw material are not particularly limited. However, in order to achieve both high input and output characteristics and high energy density, it is preferable to optimize the pores of the activated carbon. Specifically, the amount of pores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V ₁ (cc/g), and the pores having a diameter of less than 20 Å calculated by the MP method are used. When the amount of pores is set to V ₂ (cc/g), (1) To obtain high input and output characteristics, it is preferable to satisfy 0.3<V ₁ ≦0.8, and 0.5≦V ₂ ≦1.0, and, according to the BET method Determination of the specific surface area of 1,500m ² / g or more 3,000m ² / g or less of activated carbon (hereinafter known as "activated carbon 1"), in addition, (2) in order to obtain a high energy density, the preferred system satisfies 0.8 <V ₁ ≦2.5, and 0.8<V ₂ ≦3.0, and the activated carbon with a specific surface area measured by the BET method of 2,300 m ² /g or more and 4,000 m ² /g or less (hereinafter also referred to as “activated carbon 2”).

Hereinafter, the above-mentioned (1) activated carbon 1 and the above-mentioned (2) activated carbon 2 will be individually described in order.

(Activated carbon 1)

The pore volume V _{1 in the} activated carbon 1 is preferably a value greater than 0.3 cc/g in terms of increasing the input/output characteristics when incorporated into the power storage element. On the other hand, in terms of suppressing the decrease in the bulk density of the positive electrode, it is preferably 0.8 cc/g or less. The above V _{1 is} more preferably 0.35 cc/g or more and 0.7 cc/g or less, and still more preferably 0.4 cc/g or more and 0.6 cc/g or less.

The pore volume V _{2 of the} activated carbon 1 is preferably 0.5 cc/g or more in order to increase the specific surface area of the activated carbon and increase the capacity. On the other hand, in terms of suppressing the volume of activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume, it is preferably 1.0 cc/g or less. The above V _{2 is} more preferably 0.6 cc/g or more and 1.0 cc/g or less, and still more preferably 0.8 cc/g or more and 1.0 cc/g or less. In addition, the lower limit and the upper limit can be arbitrarily combined.

The ratio of the pore volume V ₁ to the micro pore volume V ₂ (V ₁ /V ₂ ) in the activated carbon 1 is preferably in the range of 0.3≦V ₁ /V ₂ ≦0.9. That is, to increase the ratio of the amount of mesopores to the amount of micropores to such an extent that the high capacity can be maintained and the decrease in output characteristics can be suppressed, V ₁ /V _{2 is} preferably 0.3 or more. On the other hand, to increase the ratio of the amount of micropores to the amount of mesopores to such an extent that high output characteristics can be maintained and capacity reduction can be suppressed, V ₁ /V _{2 is} preferably 0.9 or less. The more preferable range of V ₁ /V ₂ is 0.4≦V ₁ /V ₂ ≦0.7, and the more preferable range of V ₁ /V ₂ is 0.55≦V ₁ /V ₂ ≦0.7. In addition, the lower limit and the upper limit can be arbitrarily combined.

The average pore diameter of the activated carbon 1 is preferably at least 17 Å, more preferably at least 18 Å, and even more preferably at least 20 Å in terms of further increasing the output of the obtained energy storage device. In addition, in terms of maximizing capacity, the average pore diameter of activated carbon 1 is preferably 25 Å or less.

The BET specific surface area of the activated carbon 1, preferably based 1,500m ² / 3,000m ² g or more / g or less, more preferably based 1,500m ² / g or more 2,500m ² / g or less. When the BET specific surface area is 1,500 m ² /g or more, good energy density is easily obtained. On the other hand, when the BET specific surface area is 3,000 m ² /g or less, it is not necessary to add a large amount of binder in order to maintain electrode strength. Therefore, the performance per electrode volume becomes higher. In addition, the lower limit and the upper limit can be arbitrarily combined.

The activated carbon 1 having the characteristics described above can be obtained, for example, using the raw materials and processing methods described below.

In this embodiment, the carbon source used as the raw material of activated carbon 1 is not particularly limited. Examples include: wood, wood flour, coconut shell, by-products in the manufacture of pulp, bagasse, molasses and other plant-based raw materials; peat, sub-coal, lignite, bituminous coal, anthracite, petroleum distillation residue components, petroleum pitch, Fossil raw materials such as coke and coal tar; phenol resin, vinyl chloride resin, vinyl acetate Various synthetic resins such as ester resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, polyamide resin, etc.; polybutene, polybutadiene Synthetic rubber such as olefin, polychloroprene, etc.; other synthetic wood, synthetic pulp, etc., and these carbides. Among these raw materials, from the viewpoint of mass production response and cost, plant-based raw materials such as coconut shells and wood flour, and these carbides are preferred, and particularly preferred are coconut shell carbides.

As a method of carbonizing and activating activated carbon 1 from these raw materials, conventional methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method can be used.

The carbonization method of these raw materials can be exemplified by using inert gas such as nitrogen, carbon dioxide, helium, argon, xenon, neon, carbon monoxide, combustion exhaust gas, etc., or using this inert gas as a main component and mixing with other gases The mixed gas is calcined at, for example, 400 to 700°C, preferably 450 to 600°C for 30 minutes to 10 hours.

The activation method of the carbide obtained by carbonization is preferably a gas activation method using calcination using an activation gas such as water vapor, carbon dioxide, and oxygen. Among them, it is preferable to use water vapor or carbon dioxide as the activation gas.

In the aforementioned activation method, the activation gas is preferably supplied at a rate of 0.5 to 3.0 kg/h, more preferably at 0.7 to 2.0 kg/h, and preferably at 3 to 12 hours, more preferably at 5 to 11 hours, and even more Preferably, the above-mentioned carbide is heated to 800-1,000°C (preferably) for 6-10 hours for activation.

It is also possible to activate the carbide once before the activation treatment of the carbide. In this primary activation, it is preferable to use a method of using activated gas such as steam, carbon dioxide, oxygen, etc. to calcine the carbon material at a temperature less than 900°C to perform gas activation.

By appropriately combining the calcination temperature and calcination time of the carbonization method, and the activation method The activated gas supply amount, heating rate and maximum activation temperature can produce activated carbon 1 with the above-mentioned characteristics.

The average particle size of the activated carbon 1 is preferably 2-20 μm. If the average particle diameter is 2 μm or more, the capacity per electrode volume tends to increase due to the high density of the active material layer. If the average particle size is 2 μm or more, the durability of the positive electrode active material layer is easily ensured. If the average particle diameter is 20 μm or less, it tends to be easily adapted to high-speed charge and discharge of non-aqueous lithium electricity storage devices. The average particle size is more preferably 2 to 15 μm, and even more preferably 3 to 10 μm. The upper limit and lower limit of the range of the average particle diameter can be arbitrarily combined.

(Activated Carbon 2)

The amount of pores V _{1 in the} activated carbon 2 is preferably a value greater than 0.8 cc/g from the viewpoint of increasing the output characteristics when incorporated in the power storage device. V ₁ is preferably 2.5 cc/g or less from the viewpoint of suppressing the decrease in capacity of the electric storage element. The above V _{1 is} more preferably 1.00 cc/g or more and 2.0 cc/g or less, and still more preferably 1.2 cc/g or more and 1.8 cc/g or less.

The pore volume V _{2 of the} activated carbon 2 is preferably greater than 0.8 cc/g in order to increase the specific surface area of the activated carbon and increase the capacity. V ₂ is preferably 3.0 cc/g or less from the viewpoint of increasing the density of activated carbon as an electrode and increasing the capacity per unit volume. The above V ₂ is more preferably greater than 1.0 cc/g and less than 2.5 cc/g, and still more preferably 1.5 cc/g or more and 2.5 cc/g or less.

Activated carbon 2 having the above-mentioned mesopore volume and micropore volume has a BET specific surface area higher than that of conventional activated carbon used as an electric double layer capacitor or a lithium ion capacitor. The specific value of the BET specific surface area of the activated carbon 2 is preferably 2,300 m ² /g or more and 4,000 m ² /g or less. The lower limit of the BET specific surface area, more preferably based 3,000m ² / g or more, further more preferably based 3,200m ² / g or more. The upper limit of the BET specific surface area is more preferably 3,800 m ² /g or less. When the BET specific surface area is 2,300 m ² /g or more, good energy density is easily obtained. When the BET specific surface area is 4,000 m ² /g or less, it is not necessary to add a large amount of binder in order to maintain electrode strength, so each electrode volume The performance becomes higher.

The V ₁ , V ₂ and BET specific surface areas of the activated carbon 2 can be arbitrarily combined within the upper and lower limits of the appropriate range described above.

The activated carbon 2 having the characteristics described above can be obtained, for example, using the raw materials and processing methods described below.

The carbon source used as the raw material of the activated carbon 2 is not particularly limited as long as it is generally used as the carbon source of the activated carbon raw material, and examples include plant-based raw materials such as wood, wood flour, coconut shells, etc.; petroleum pitch, coke, etc. Fossil raw materials; various synthetic resins such as phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, etc. Among these raw materials, phenol resin and furan resin are particularly suitable for producing activated carbon with high specific surface area.

Examples of methods for carbonizing these raw materials or heating methods for activation treatment include conventional methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. The environment during heating is the use of inert gases such as nitrogen, carbon dioxide, helium, and argon, or a mixture of these inert gases with other gases as the main component. The carbonization temperature is preferably 400 to 700°C, the lower limit is preferably 450°C or higher, more preferably 500°C or higher, and the upper limit is preferably 650°C or lower. The calcination time is preferably 0.5 to 10 hours.

The activation method of the carbide after the carbonization treatment includes a gas activation method using calcination of an activation gas such as steam, carbon dioxide, and oxygen, and an alkali metal activation method in which a heating treatment is performed after mixing with an alkali metal compound. The production of activated carbon with a high specific surface area is preferably performed by an alkali metal activation method.

In this activation method, for example, carbide, potassium hydroxide (KOH), After mixing alkali metal compounds such as sodium hydroxide (NaOH) at a mass ratio of 1:1 or more (that is, the amount of alkali metal compound is the same as the amount of carbide, or more), under an inert gas environment, It is preferably in the range of 600 to 900°C, more preferably in the range of 650°C to 850°C, heated for 0.5 to 5 hours (preferably), and then washed with acid and water to remove the alkali metal compound, and further dried.

The mass ratio of carbide to alkali metal compound (=carbide: alkali metal compound) is preferably 1:1 or more. As the amount of alkali metal compound increases, the amount of mesopores increases. However, there is a tendency for the amount of pores to increase sharply around the vicinity of the mass ratio of 1:3.5, so the better-quality alkali metal compound is more than 1:3. Although the mass ratio of the carbide to the alkali metal compound increases as the alkali metal compound increases, the pore volume becomes larger. However, considering the treatment efficiency such as subsequent washing, it is preferably 1:5.5 or less.

In order to increase the amount of micropores without increasing the amount of mesopores, it is sufficient to use a larger amount of carbide and KOH for mixing during activation. In order to increase both the amount of micropores and the amount of mesopores, a larger amount of KOH may be used. In order to mainly increase the amount of mesopores, it is preferable to perform the steam activation after the alkali activation treatment.

The average particle size of the activated carbon 2 is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less.

(Use of activated carbon)

Activated carbon 1 and 2, respectively, may be one kind of activated carbon, or a mixture of two or more kinds of activated carbon, and the mixture as a whole shows the above characteristic values.

Activated carbons 1 and 2 can be used by selecting any of these, or they can be used by mixing them.

The positive electrode active material may also contain materials other than activated carbon 1 and activated carbon 2 (for example, activated carbon that does not have the specific V ₁ and/or V ₂ described above, or materials other than activated carbon (for example, high conductivity Molecules, etc.)). In the illustrated example, when the positive electrode active material layer does not contain the lithium transition metal oxide described later, the content of activated carbon is preferably 40% by mass or more and 95% by mass or less, and more preferably 50% by mass or more and 90% by mass %the following. If the content of activated carbon is 40% by mass or more, the decomposition of the alkali metal compound in the positive electrode active material layer in the pre-doping step can be promoted. If the content of activated carbon is 95% by mass or less, the peeling strength of the electrode is improved, and the shedding of the positive electrode active material layer in the pre-doping step can be suppressed.

(Lithium transition metal oxide)

Lithium transition metal oxides include transition metal oxides that can occlude and release lithium. The transition metal oxide used as the positive electrode active material is not particularly limited. Examples of lithium transition metal oxides include oxides containing lithium and at least one element selected from the group consisting of cobalt, nickel, manganese, iron, vanadium, and chromium. Specific examples of lithium transition metal oxides include compounds represented by the following formula: Li _x CoO ₂ {where x satisfies 0≦x≦1. }, Li _x NiO ₂ {where x satisfies 0≦x≦1. }, Li _x Ni _y M _(1-y) O ₂ {where M is an element selected from the group consisting of Co, Mn, Al, Fe, Mg, and Ti, and x satisfies 0≦x≦ 1, and y satisfies 0.2<y<0.97. }, Li _x Ni _1/3 Co _1/3 Mn _1/3 O ₂ {where x satisfies 0≦x≦1. }, Li _x MnO ₂ {where x satisfies 0≦x≦1. }, α-Li _x FeO ₂ {where x satisfies 0≦x≦1. }, Li _x VO ₂ {where x satisfies 0≦x≦1. }, Li _x CrO ₂ {where x satisfies 0≦x≦1. }, Li _x FePO ₄ {where x satisfies 0≦x≦1. }, Li _x MnPO ₄ {where x satisfies 0≦x≦1. }, Li _z V ₂ (PO ₄ ) ₃ {where, z satisfies 0≦z≦3. }, Li _x Mn ₂ O ₄ {where x satisfies 0≦x≦1. }, Li _x M _y Mn _(2-y) O ₄ {where M is an element selected from the group consisting of Co, Mn, Al, Fe, Mg, and Ti, and x satisfies 0≦x≦ 1, and y satisfies 0.2<y<0.97. }, Li _x Ni _a Co _b Al _(1-ab) O ₂ {where x satisfies 0≦x≦1, and a and b satisfy 0.2<a<0.97 and 0.2<b<0.97. }, Li _x Ni _c Co _d Mn _(1-cd) O ₂ {where x satisfies 0≦x≦1, and c and d satisfy 0.2<c<0.97 and 0.2<d<0.97. }.

Among these, from the viewpoint of high capacity, low resistance, cycle characteristics, decomposition of lithium compounds, and suppression of the shedding of the positive electrode active material during pre-doping, the above formula Li _x Ni _a Co _b Al _{( 1-ab)} O ₂ , Li _x Ni _c Co _d Mn _(1-cd) O ₂ , Li _x CoO ₂ , Li _x Mn ₂ O ₄ , Li _x FePO ₄ , Li _x MnPO ₄ , or Li _z V ₂ ( PO ₄ ) ₃ represents the compound.

In this embodiment, as long as the positive electrode precursor contains a lithium compound that is different from the positive electrode active material and is doped with lithium (also referred to as "lithium ion doping" in the aforementioned industry.), the lithium compound can be used as a lithium ion doping The dopant source is lithium doped to the negative electrode, so even if the transition metal compound does not contain lithium ions in advance (that is, even if x=0 or z=0), it can also be used as a non-aqueous lithium storage element for electrochemical charging and discharging .

The average particle size of the lithium transition metal oxide is preferably 0.1-20 μm. If the average particle diameter is 0.1 μm or more, the capacity per electrode volume tends to increase due to the high density of the positive electrode active material layer. Although the average particle diameter is small, the disadvantage of low durability may occur, but as long as the average particle diameter is 0.1 μm or more, such a defect is not likely to occur. If the average particle size is 20 μm or less, it tends to be easily suitable for high-speed charge and discharge. The average particle size of lithium transition metal oxide is better 0.5~15μm, more preferably 1~10μm.

In addition, the average particle size of the lithium transition metal oxide is preferably smaller than the average particle size of the carbon material described above. If the average particle size of the lithium transition metal oxide is small, the lithium transition metal oxide can be disposed in the void formed by the carbon material with a large average particle size, and the resistance can be reduced.

The structure of lithium transition metal oxides includes high capacity, low resistance, cycle characteristics, decomposition of lithium compounds, suppression of capacity degradation of lithium transition metal oxides during pre-doping, and suppression of shedding of positive electrode active materials during pre-doping From a viewpoint, the lithium transition metal oxide is preferably at least one selected from the group consisting of layered compounds, spinel compounds, and olivine compounds.

The lithium transition metal oxide may be one kind, or a mixture of two or more materials, and the mixture as a whole shows the aforementioned characteristic values.

The positive electrode active material may also contain materials other than the above lithium transition metal oxide (for example, conductive polymers, etc.).

When the content of the lithium transition metal oxide in the total solid content of the positive electrode coating solution is K ₂ , K ₂ is 5% by mass or more and 35% by mass or less, preferably 10% by mass or more and 30% by mass or less .

In the case of using a carbon material and a lithium transition metal oxide as the positive electrode active material, the content of the activated carbon 1 in the positive electrode active material layer, that is, when the mass ratio of the carbon material in the positive electrode active material layer is set to A ₁ , in addition, When the positive electrode precursor contains a conductive filler, a binder, a dispersion stabilizer, etc., when the total amount of carbon materials and these materials is A ₁ , A _{1 is} preferably 15% by mass or more and 65% by mass or less. The best line is 20% by mass or more and 50% by mass or less. If A ₁ is 15% by mass or more, since the contact area of the carbon material with high conductivity and the alkali metal compound increases, the oxidation reaction of the alkali metal compound can be promoted in the pre-doping step, and the pre-doping can be performed in a short time miscellaneous. If A ₁ is 65% by mass or less, the bulk density of the positive electrode active material layer increases, and the capacity can be increased. When the content of the lithium transition metal oxide in the positive electrode active material layer is A ₂ , A _{2 is} preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. If A ₂ is 5% by mass or more, the bulk density of the positive electrode active material layer increases and the capacity can be increased. If A ₂ is less than 35% by mass, since the contact area of the carbon material with high conductivity and the alkali metal compound increases, the oxidation reaction of the alkali metal compound can be promoted in the pre-doping step, and the pre-doping can be performed in a short time miscellaneous.

The content ratio of the positive electrode active material in the positive electrode active material layer is preferably 35% by mass or more and 95% by mass or less based on the total mass of the positive electrode active material layer of the positive electrode precursor. The lower limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, and still more preferably 55% by mass or more. The upper limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, and still more preferably 80% by mass or less. By setting the content ratio to the aforementioned range, more suitable charge and discharge characteristics are exhibited.

(Use of positive active material)

The positive electrode coating liquid, the content of the lithium transition metal oxide of K _2, and K content of the carbon material of the ratio K _{1 2} / K ₁ line 0.1 to 2.0, preferably 0.2 or more and 1.2 or less based. If K ₂ /K ₁ is 0.1 or more, the bulk density of the positive electrode active material layer can be increased and the capacity can be increased. If K ₂ /K ₁ is 2.0 or less, the resistance of electrons between activated carbons can be improved, and the resistance can be reduced, and the decomposition area of alkali metal compounds can be promoted due to the increased contact area between activated carbon and alkali metal compounds.

The positive electrode precursor, a carbon material and a lithium transition metal oxide as a positive electrode active material of the case, the content of the lithium transition metal oxide with the carbon material content A ₂ ratio of the sum A ₁ A ₂ / A _1, 0.10 or more and 2.00 or less based It is preferably 0.20 or more and 1.20 or less, and more preferably 0.20 or more and 1.10 or less. If A ₂ /A ₁ is 0.10 or more, the bulk density of the positive electrode active material layer can be increased and the capacity can be increased. When A ₂ /A ₁ is 2.00 or less, the electron conduction between the activated carbon is improved to achieve a low resistance, and the contact area between the activated carbon and the alkali metal compound is increased to promote the decomposition of the alkali metal compound.

(Alkali metal compound)

Examples of the alkali metal compound in this embodiment include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lithium oxide, and lithium hydroxide. By decomposing and releasing cations in the cathode precursor, the anode is reduced. It can be pre-doped. It is suitable to use more than one type of alkali metal carbonate selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate. More preferably, it is lithium carbonate, sodium carbonate, or carbonic acid. Potassium is more preferably lithium carbonate from the viewpoint of higher capacity per unit weight.

The alkali metal compound contained in the positive electrode coating liquid may be one kind, or may contain two or more kinds of alkali metal compounds. In addition, the positive electrode coating solution of the present embodiment may contain at least one alkali metal compound, and may also contain more than one of the following substances: M is one or more types of M selected from Li, Na, K, Rb, and Cs Carboxylates such as oxides such as ₂ O, hydroxides such as MOH, halides such as MF and MCl, and RCOOM (where R is H, alkyl, or aryl). In addition, the alkali metal compound of this embodiment may also contain more than one of the following substances: alkaline earth metal carbonate, alkaline earth metal oxidation selected from the group consisting of BeCO ₃ , MgCO ₃ , CaCO ₃ , SrCO ₃ , and BaCO ₃ Compounds, alkaline earth metal hydroxides, alkaline earth metal halides, or alkaline earth metal carboxylates.

The weight ratio X ₃ of the alkali metal compound in the total solid content in the positive electrode coating solution is 10% by mass or more and 50% by mass or less. If X ₃ is 10% by mass or more, a sufficient amount of alkali metal ions can be pre-doped to the negative electrode, and the capacity of the non-aqueous lithium electric storage element is increased. If X ₃ is 50% by mass or less, since the electron conduction in the positive electrode precursor can be improved, the decomposition of the alkali metal compound can be efficiently performed.

The positive electrode coating liquid includes the above two or more alkali metalizations in addition to the alkali metal compound Compound, or alkaline earth metal compound, it is preferable to prepare the positive electrode coating liquid in the following manner: the total amount of the alkali metal compound and alkaline earth metal compound is 10 masses relative to the total solid content in the positive electrode coating liquid The ratio of% or more and 50% by mass or less is included in the positive electrode coating solution.

Preferably, the positive electrode precursor is prepared with the mass ratio A ₃ of the alkali metal compound contained in the positive electrode active material layer of the positive electrode precursor being 10% by mass or more and 50% by mass or less. If A ₃ is 10% by mass or more, a sufficient amount of alkali metal ions can be pre-doped into the negative electrode, and the capacity of the non-aqueous lithium electricity storage element is increased. If A ₃ is 50% by mass or less, since the electron conduction in the positive electrode precursor can be improved, the alkali metal compound can be efficiently decomposed.

When the positive electrode precursor contains the above two or more alkali metal compounds or alkaline earth metal compounds in addition to the alkali metal compound, it is preferable to prepare the positive electrode precursor in the following manner: the total amount of the alkali metal compound and the alkaline earth metal compound, in The ratio of 10% by mass to 50% by mass in the positive electrode active material layer on each side of the positive electrode precursor.

High load charge and discharge characteristics

When charging and discharging a non-aqueous lithium electricity storage element, alkali metal ions and anions in the electrolyte move with charging and discharging, and then react with the active material. Here, the activation energies for the insertion reaction and the detachment reaction of the ions of the active substance are different from each other. Therefore, especially in the case where the load of charge and discharge is large, the ions cannot follow the change of charge and discharge, which causes it to accumulate in the active material. As a result, the resistance of the non-aqueous lithium electricity storage element increases due to the decrease in the electrolyte concentration in the overall electrolyte.

However, if the positive electrode precursor contains an alkali metal compound, the alkali metal compound is decomposed by oxidation, and while the alkali metal ions used for the pre-doping of the negative electrode are released, a good hole that can maintain the electrolyte is formed inside the positive electrode. The positive electrode with such a hole, during charge and discharge, is supplied with ions through the electrolyte formed in the hole near the active material at any time, so the high load charge and discharge cycle Sexual promotion.

The alkali metal compound contained in the positive electrode precursor is oxidatively decomposed by applying a high voltage when forming a non-aqueous lithium electricity storage element to release alkali metal ions, and is reduced at the negative electrode to perform pre-doping. Therefore, the aforementioned pre-doping step can be performed in a short time by promoting the aforementioned oxidation reaction. In order to promote the aforementioned oxidation reaction, it is important to contact the alkali metal compound of the insulator with the positive electrode active material to ensure electron conduction, and to diffuse the cations released after the reaction in the electrolyte. Therefore, it is important that the alkali metal compound appropriately covers the surface of the positive electrode active material.

Various methods can be used to form particles of alkali metal compounds and alkaline earth metal compounds. For example, pulverizers such as ball mills, bead mills, ring roll mills, jet mills, and rod mills can be used.

The quantification of the alkali metal elements and alkaline earth metal elements can be calculated based on ICP-AES, atomic absorption spectrometry, X-ray fluorescence analysis, neutron activation analysis, ICP-MS, and the like.

In the present embodiment, the average particle size of the alkali metal compound is preferably 0.1 μm or more and 10 μm or less. If the average particle diameter is 0.1 μm or more, the dispersibility in the positive electrode precursor is excellent. If the average particle size is 10 μm or less, the surface area of the alkali metal compound increases and the decomposition reaction proceeds efficiently.

In addition, the average particle diameter of the alkali metal compound is preferably smaller than the average particle diameter of the carbon material described above. If the average particle size of the alkali metal compound is smaller than the average particle size of the carbon material, the electron conduction of the positive electrode active material layer is improved, which may contribute to the reduction of the resistance of the electrode body or the storage element.

The method for measuring the average particle size of the alkali metal compound in the positive electrode precursor is not particularly limited, and can be calculated from the SEM image of the cross section of the positive electrode and the SEM-EDX image. The formation method of the positive electrode cross section can be processed by the following BIB: irradiating an Ar beam from the upper part of the positive electrode, and making a smooth cross section along the end of the shielding plate provided directly above the sample.

[Lithium compound other than positive electrode active material]

The positive electrode active material layer of the positive electrode of this embodiment contains a lithium compound other than the positive electrode active material.

The lithium compound other than the positive electrode active material is preferably a compound that can decompose at the positive electrode when lithium is doped and release lithium ions. For example, a compound selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, and chloride At least one of lithium, lithium bromide, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate. Among them, at least one selected from the group consisting of lithium carbonate, lithium oxide, and lithium hydroxide is more suitable. From the viewpoint of being usable in air and having low hygroscopicity, lithium carbonate is more preferably used. Such a lithium compound can be decomposed by applying a voltage and functions as a dopant source for lithium doping the negative electrode, while forming holes in the positive electrode active material layer, so that the retention of the electrolyte can be formed A positive electrode excellent in ion conductivity.

(Lithium compounds other than the positive electrode active material of the positive electrode precursor)

In the positive electrode precursor, the lithium compound other than the positive electrode active material is preferably in the form of particles. The average particle diameter of the lithium compound contained in the positive electrode precursor is preferably 0.1 μm or more and 100 μm or less. The upper limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 50 μm or less, still more preferably 20 μm or less, and even more preferably 10 μm or less. The lower limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 0.3 μm or more, and still more preferably 0.5 μm or more. If the average particle diameter of the lithium compound is 0.1 μm or more, the pores left by the lithium compound of the positive electrode after the oxidation reaction have a sufficient volume for maintaining the electrolyte, so the high-load charge-discharge characteristics are improved. If the average particle size of the lithium compound is 100 μm or less, the surface area of the lithium compound will not be excessively reduced, so the rate of oxidation reaction of the lithium compound can be ensured. The upper limit and lower limit of the range of the average particle diameter of the lithium compound can be arbitrarily combined.

Various methods can be used to form the fine particles of the lithium compound. For example, you can make Use pulverizers such as ball mills, bead mills, ring roller mills, jet mills, rod mills, etc.

The content ratio of the lithium compound in the positive electrode active material layer of the positive electrode precursor, based on the total mass of the positive electrode active material layer of the positive electrode precursor, is preferably 5 mass% or more and 60 mass% or less, more preferably 10 mass% or more 50 Mass% or less. By setting the content ratio in this range, it is possible to give an appropriate degree of porosity to the positive electrode while exerting an appropriate function as a dopant source for the negative electrode, and the two interact with each other to provide power storage with high load charge and discharge efficiency. Components, so it is better. The upper limit and lower limit of the range of the content ratio can be arbitrarily combined.

(Lithium compounds other than the positive electrode active material of the positive electrode)

The lithium compound other than the positive electrode active material contained in the positive electrode is preferably 1% by mass or more and 50% by mass or less, and more preferably 2.5% by mass or more and 25% by mass or less based on the total mass of the positive electrode active material layer of the positive electrode. When the amount of the lithium compound is 1% by mass or more, the decomposition reaction of the electrolyte solvent on the positive electrode in a high-temperature environment is suppressed by lithium carbonate, so the high-temperature durability is improved, and when the amount of the lithium compound is 2.5% by mass or more, the effect changes Notable. When the amount of the lithium compound is 50% by mass or less, the electron conductivity between the positive electrode active materials is less hindered by the lithium compound, so it shows high input and output characteristics; when the amount of the lithium compound is 25% by mass or less, especially It is particularly preferable from the viewpoint that input/output characteristics become good. In addition, the lower limit and the upper limit can be arbitrarily combined.

(Identification method of lithium compounds other than the positive electrode active material in the positive electrode)

The identification method of the lithium compound other than the positive electrode active material included in the positive electrode is not particularly limited, and for example, it can be identified by the following method. The identification of lithium compounds is preferably performed by combining a plurality of analysis methods selected from the following: SEM-EDX, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), solid-state ⁷ Li-NMR, XRD (X-ray diffraction ), TOF-SIMS (time-of-flight secondary ion mass spectrometry), AES (Aojie electron spectroscopy), TPD/MS (programmed temperature-controlled desorption mass spectrometry), DSC (differential scanning calorimetry), etc.

(Other components of positive electrode active material layer)

The positive electrode coating liquid of this embodiment and the positive electrode active material layer of the positive electrode precursor include a polyacrylic acid compound as a binder in addition to the positive electrode active material and the alkali metal compound, and may also include a conductive filler and a dispersant as needed , PH adjusting agent and other arbitrary components.

Examples of the aforementioned conductive fillers include conductive carbonaceous materials having higher conductivity than the positive electrode active material. Such conductive fillers are preferably Ketjen Black, Acetylene Black, Vapor-grown Carbon Fiber, Graphite, Flake Graphite, Nano Carbon Tube, Graphene, and mixtures thereof.

The mixing amount of the conductive filler in the positive electrode coating liquid and the positive electrode active material layer of the positive electrode precursor is preferably in the range of 0 to 20 parts by mass, more preferably 1 to 15 parts by mass relative to 100 parts by mass of the positive electrode active material. The conductive filler is preferably a blender from the viewpoint of high input. However, if the mixing amount is more than 20 parts by mass, since the content ratio of the positive electrode active material in the positive electrode active material layer becomes smaller, the energy density per volume of the positive electrode active material layer decreases, which is not preferable.

The positive electrode coating liquid and the binder in the positive electrode precursor of this embodiment feature that the polyacrylic acid compound is included. The polyacrylic acid compound is not particularly limited, and examples include polyacrylic acid; sodium polyacrylate or potassium polyacrylate after neutralizing acidic functional groups; copolymers of maleic acid, sulfonic acid, methacrylic acid, and other acrylic monomers or The sodium or potassium salt. In addition, polyacrylic acid in which a part of carboxyl groups are alkylated, or fluorinated alkylated polyacrylic acid may also be used. The average molecular weight of the polyacrylic acid compound is not particularly limited, but is preferably in the range of 5,000 to 1,000,000, more preferably 10,000 to 500,000. If the average molecular weight is 5,000 or more, the peel strength of the electrode can be improved. If the average molecular weight is 1,000,000 or less, the diffusion of ions in the electrode is improved and the input and output characteristics are improved.

The positive electrode coating liquid and the binder in the positive electrode precursor of this embodiment only need to contain a polyacrylic acid compound, and may further include, for example: PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene) Vinyl fluoride), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylate polymer, etc. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 27 parts by mass or less, and even more preferably 5 parts by mass or more and 25 parts by mass relative to 100 parts by mass of the positive electrode active material. the following. If the amount of the binder is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, if the amount of the binder is 30 parts by mass or less, it will not hinder the entry and exit and diffusion of ions to the positive electrode active material, and will exhibit high input-output characteristics.

The dispersing agent is not particularly limited, and can be, for example, selected from the group consisting of carboxymethyl cellulose, methyl cellulose, ethyl cellulose, cellulose acetate phthalate, hydroxymycelin, and hydroxypropyl methyl fiber At least one of the group consisting of element, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose phthalate, polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl acetal. The amount of the dispersant used is preferably 0 parts by mass or more and 10 parts by mass or less, and more preferably more than 0 parts by mass and 10 parts by mass or less relative to 100 parts by mass of the positive electrode active material. If the amount of the dispersant is 10 parts by mass or less, the input and output of ions to the positive electrode active material is not hindered, and high input-output characteristics are exhibited.

The dispersing solvent for the positive electrode coating liquid can be used: water, N-methyl-2-pyrrolidone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, dioxane, tetrahydrofuran , Dimethylformamide, dimethylacetamide, tetramethylurea, dimethylsulfoxide, trimethyl phosphate, alcohol, acetone, toluene, xylene, n-hexane, cyclohexane, and mixtures of these Wait.

In the case where water is used as the dispersion solvent of the coating liquid, the coating liquid becomes alkaline due to the addition of the alkali metal compound, so the pH adjusting agent may be added to the positive electrode coating liquid if necessary. The pH adjusting agent is not particularly limited, and inorganic acids and/or organic acids can be used. For example, Uses: hydrogen halide such as hydrogen fluoride, hydrogen chloride, hydrogen bromide; halogen oxyacids such as hypochlorous acid, chlorous acid, chloric acid, etc; formic acid, acetic acid, citric acid, oxalic acid, lactic acid, maleic acid, fumaric acid, etc. Carboxylic acids; methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and other sulfonic acids; nitric acid, sulfuric acid, phosphoric acid, boric acid, carbon dioxide and other acids.

The pH value of the positive electrode coating solution is preferably 6.0 or more and 13.0 or less. If the pH is above 6.0, the hydrolysis of the binder can be suppressed. If the pH value is below 13.0, the denaturation of the binder can be suppressed.

In the case of using an organic solvent other than water as the dispersion solvent of the coating liquid, the amount of water contained in the dispersion solvent is preferably 0% by mass or more and 10% by mass or less. If the amount of water is 0% by mass or more, since the alkali metal compound is slightly dissolved, the contact between the positive electrode active material or the conductive material and the alkali metal compound is increased, thereby further promoting pre-doping. If the water content is 10% by mass or less, the alkalinity of the coating liquid does not become too high, and the denaturation of the binder can be suppressed. The method of suppressing the contained water content to 10 mass% or less can be exemplified by a method of adding a dehydrating agent such as magnesium sulfate or zeolite.

[Binder for positive active material layer]

The positive electrode active material layer of the non-aqueous lithium electricity storage element of this embodiment includes a binder in addition to the positive electrode active material and the lithium compound other than the positive electrode active material.

In the non-aqueous lithium electricity storage device of this embodiment, the binder includes a polymer, and the RED value of the aforementioned polymer based on the Hansen solubility parameter of the non-aqueous electrolyte is greater than 1. Specifically, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyacrylic acid, polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer, acrylic Ester polymers and the like are preferably polyacrylic acid. Polyacrylic acid, because the RED value is greater than 1 compared to the non-aqueous electrolyte commonly used in non-aqueous lithium storage devices, the polymer will not swell due to the electrolyte, and the mechanical strength under high temperature storage will not be reduced. good. Polyacrylic acid, for preparing positive active material The coating liquid of the mass layer is also suitable from the viewpoint that it can be prepared as an aqueous solution. The polyacrylic acid referred to here refers to the broad concept including polyacrylic acid neutralization salts and bridgers in addition to unneutralized polyacrylic acid, and also includes, for example: polyacrylic acid, polyacrylic acid after neutralizing acidic functional groups , Sodium polyacrylate, and potassium polyacrylate, or maleic acid, sulfonic acid, methacrylic acid and other copolymers with acrylic monomers, part of the carboxyl group is alkylated polyacrylic acid, part of the carboxyl group is fluorinated alkylation The polyacrylic acid. The average molecular weight of polyacrylic acid is not particularly limited, but it is preferably in the range of 5,000 to 1,000,000, and more preferably in the range of 10,000 to 500,000. If the average molecular weight is 5,000 or more, the peel strength of the electrode can be improved. If the average molecular weight is 1,000,000 or less, the diffusion of ions in the electrode is improved and the input and output characteristics are improved.

Only one type of polyacrylic acid may be used, or two or more types may be used in combination.

<Hansen solubility parameter>

The Hansen solubility parameter is published by Charles M Hansen's and is widely known as an indicator of the solubility of substances with each other. The Hansen solubility parameter is composed of the following three values of D, P, and H, and these three parameters are expressed as coordinates in a 3-degree space (Hansen space).

D: (atomic) dispersion force

P: (molecule) polarizing force

H: (molecular) hydrogen bonding force

The solubility of the substances is estimated based on the distance between the coordinates of the Hansen solubility parameters of the substances shown. The closer the coordinates are to each other, the easier to dissolve, and the more distant the more difficult to dissolve.

The Hansen solubility parameter of the non-aqueous electrolyte can be calculated from the chemical structure and composition ratio of the components. In this case, the software HSPiP developed by Hansen et al. (for efficient operation of Hansen Solubility Parameters in Practice: Windows for HSP [Registrar Sign] Use software) to obtain.

In order to obtain the Hansen solubility parameter of the polymer, it is necessary to dissolve (mix) the polymer in a plurality of solvents with known Hansen solubility parameters, and use a polymer that can dissolve the polymer and a Hansen that cannot dissolve the polymer. The solubility parameters are plotted in Hansen space. The center of the sphere formed from the drawing set of the solvent that can dissolve the polymer (the Hansen dissolution sphere of the polymer, hereinafter referred to as "the dissolution sphere of the polymer") is set as the Hansen solubility parameter of the polymer. The polymer dissolution ball and Hansen solubility parameters can also be calculated using the software HSPiP.

<RED value of polymer to non-aqueous electrolyte>

For the RED value of a polymer to a non-aqueous electrolyte, when the distance between the Hansen solubility parameter of the polymer and the Hansen solubility parameter of the electrolyte is Ra, and the interaction radius of the dissolution sphere radius of the polymer is R0, Represented by RED=Ra/R0. In the case where the RED value of the polymer to the non-aqueous electrolyte is greater than 1, the Hansen solubility parameter of the non-aqueous electrolyte is outside the dissolution ball of the polymer. Therefore, the non-aqueous electrolyte and polymer thus combined are difficult to dissolve. Therefore, even if the non-aqueous lithium electricity storage device is stored at a high temperature, the swelling of the binder (polymer) caused by the non-aqueous electrolyte can be suppressed, the strength of the positive electrode can be suppressed from decreasing, and the resistance can be kept low.

The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 27 parts by mass or less, and even more preferably 5 parts by mass or more and 25 parts by mass relative to 100 parts by mass of the positive electrode active material. the following. If the amount of binder used is 1 part by mass or more, sufficient electrode strength is exhibited. On the other hand, if the amount of the binder used is 30 parts by mass or less, it will not hinder the entry and exit and diffusion of ions to the positive electrode active material, and will exhibit high input and output characteristics.

[Any component of the positive electrode active material layer]

The positive electrode active material layer of this embodiment type except the positive electrode active material and the positive electrode active material In addition to the lithium compound and the binder, any components such as conductive filler, binder, dispersion stabilizer, etc. may be included as needed.

The conductive filler is not particularly limited, and for example, acetylene black, Ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, and mixtures thereof can be used. The amount of the conductive filler used is preferably 30 parts by mass or less, more preferably 0.01 parts by mass or more and 20 parts by mass or less, and even more preferably 1 part by mass or more and 15 parts by mass or less relative to 100 parts by mass of the positive electrode active material. If the amount of the conductive filler is 30 parts by mass or less, the content ratio of the positive electrode active material in the positive electrode active material layer can be increased, and the energy density per volume of the positive electrode active material layer can be improved, which is preferable.

The dispersion stabilizer is not particularly limited, and for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), cellulose derivatives and the like can be used. The amount of the dispersion stabilizer used is preferably 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the positive electrode active material. If the amount of the dispersion stabilizer used is 10 parts by mass or less, it will not hinder the entry and diffusion of ions to the positive electrode active material, and will exhibit high input and output characteristics.

In the case where water is used as the solvent of the coating liquid, the coating liquid may become alkaline due to the addition of the lithium compound. Therefore, if necessary, a pH adjusting agent may be added to the coating liquid. The pH adjusting agent is not particularly limited. For example, hydrogen halides such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, etc.; halogen oxyacids such as hypochlorous acid, chlorous acid, chloric acid, etc.; formic acid, acetic acid, citric acid, Carboxylic acids such as oxalic acid, lactic acid, maleic acid, fumaric acid, etc.; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid; nitric acid, sulfuric acid, phosphoric acid, boric acid, carbon dioxide and other acids.

[Positive collector]

The material constituting the positive electrode current collector of this embodiment type has no special features as long as it has high electron conductivity and is not likely to cause deterioration due to elution of the electrolyte and reaction with the electrolyte or ions. Without limitation, it is preferably a metal foil. The positive electrode current collector of the non-aqueous lithium electricity storage element of this embodiment is particularly preferably aluminum foil.

The metal foil may be a metal foil without bumps, through holes, etc., or a metal foil with bumps, such as embossing, chemical etching, electrolysis, spraying, etc., or a porous metal mesh ( Expand metal, punching metal, etched foil and other metal foils with through holes.

The thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the positive electrode can be sufficiently maintained. For example, it is preferably 1 to 100 μm.

In addition, an anchor layer of a conductive material including graphite, flake graphite, carbon nanotubes, graphene, Ketjen black, acetylene black, vapor-grown carbon fiber, etc. may be provided on the surface of the metal foil. By providing the anchor layer, the electrical conductivity between the positive electrode current collector and the positive electrode active material layer is improved, and the resistance can be reduced. The thickness of the anchor layer is preferably 0.1 μm or more and 5 μm or less on each side of the positive electrode current collector.

In the case of using water as the solvent of the coating liquid, since the coating liquid becomes alkaline due to the addition of the lithium compound, it is preferable to use an alkali-resistant binder in the anchor layer.

[Manufacture of positive electrode coating liquid]

In the present embodiment, the positive electrode coating liquid of the non-aqueous lithium electricity storage element can be manufactured by a known coating liquid manufacturing technology for lithium ion batteries, electric double layer capacitors, and the like. For example, the positive electrode active material, the alkali metal compound, and other optional components used as needed may be dispersed or dissolved in water or an organic solvent in any order to prepare a slurry-like coating liquid.

In one embodiment, the method for manufacturing a positive electrode coating liquid of this embodiment includes: solid material containing a carbon material, a desired lithium transition metal oxide, and an alkali metal compound The components are dry mixed, and thereafter, the solid components and the dispersion solvent after the dry mixing are mixed to disperse the solid components. More specifically, for example, part or all of the solid component including the carbon material, lithium transition metal oxide, and alkali metal compound may be dry mixed (also referred to as "dry blending"), and then, a dispersion solvent may be added, and /Or dissolve or disperse the liquid or slurry-like substance of the polyacrylic acid compound, dispersant or pH adjuster in the dispersing solvent to prepare the positive electrode coating liquid. In addition, it is also possible to dissolve or disperse the polyacrylic acid compound, dispersant or pH adjusting agent in liquid or slurry-like substances in the dispersing solvent, and add the carbon material, lithium transition metal oxide and alkali metal compound previously dry mixed Modulation of the solid content. The method of dry mixing is not limited, and for example, a ball mill or the like can be used.

In another embodiment, the carbon material and the alkali metal compound may be dry mixed, and then, the other solid components and the dispersion solvent may be mixed and dispersed in any order. According to this order, by mixing the carbon material and the alkali metal compound more closely, the conductivity of the alkali metal compound can be improved, and the alkali metal compound in the pre-doping step is easily decomposed, which is preferable. More specifically, for example, part or all of the carbon material and the alkali metal compound may be dry-mixed, and then lithium transition metal oxide may be added for dry-mixing, and thereafter, a dispersion solvent may be added, and/or dissolved or dispersed in the dispersion solvent. A liquid or slurry-like substance of polyacrylic acid compound, dispersant or pH adjuster, to prepare a positive electrode coating liquid. In addition, it is also possible to dissolve or disperse the polyacrylic acid compound, dispersant or pH adjusting agent in the liquid or slurry-like substance in the dispersing solvent. It is prepared by metal oxide and the like. The method of dry mixing is not limited, and for example, a ball mill or the like can be used.

Further in another embodiment, the conductive material and the aforementioned alkali metal compound may be dry mixed, and then, the other solid components and the aforementioned dispersion solvent may be mixed and divided in any order Scattered. According to this sequence, by coating the conductive material with an alkali metal compound having low conductivity, the conductivity of the alkali metal compound can be improved, and the alkali metal compound in the pre-doping step is easily decomposed, which is preferable. More specifically, for example, part or all of the conductive material and the alkali metal compound may be dry-mixed, followed by adding a carbon material and a lithium transition metal oxide to dry-mix, and thereafter, adding a dispersion solvent and/or in a dispersion solvent Dissolve or disperse liquid or slurry-like substances of polyacrylic acid compound, dispersant or pH adjuster to prepare positive electrode coating liquid. In addition, it is also possible to dissolve or disperse the polyacrylic acid compound, dispersant, or pH adjuster in the liquid or slurry form in the dispersing solvent, and add the conductive material, alkali metal compound, and carbon material that have been dry-mixed in advance in any order. And lithium transition metal oxide. The method of dry mixing is not limited, and for example, a ball mill or the like can be used.

The solid content ratio of the positive electrode coating liquid is preferably 15% or more and 60% or less. If the solid content ratio is 15% or more, the coating can be dried under stable conditions. If the solid content ratio is 60% or less, the occurrence of coating streaks or cracks during coating can be suppressed. The solid content ratio refers to the ratio of the total weight of the solid content of the carbon material, polyacrylic acid compound, alkali metal compound, and other lithium transition metal oxides or conductive materials in the total weight of the coating liquid.

The dispersion method for preparing the positive electrode coating liquid is not particularly limited, and it is more suitable for use: bead mill, ball mill, jet mill, homogenizer, emulsifying and dispersing machine, and rotation. Dispersers such as revolution mixers, homogeneous phase dispersers, multi-axis dispersers, planetary mixers, thin-film rotary high-speed mixers, etc. In addition, a plurality of such dispersing machines may be combined and dispersed. In order to obtain a coating liquid with a good dispersion state, for example, when a thin film rotary high-speed mixer is used, it is preferably dispersed at a peripheral speed of 1 m/s or more and 50 m/s or less. If the peripheral speed is 1 m/s or more, various materials are well dissolved or dispersed, which is preferable. In addition, if the peripheral speed is less than 50m/s, there will be no heat or shear damage caused by the dispersion of various materials It is better if the condition is bad, and re-aggregation will not occur. In order to suppress the destruction of various materials caused by the dissipated heat, it is preferable to use a method of dispersing the coating liquid while cooling.

After dispersing the coating liquid, defoaming is preferably performed. The method of defoaming is not particularly limited, and examples include: a method of stirring the coating liquid at a low speed under a reduced pressure environment, a method of standing the coating liquid, and the use of rotation. The method of low speed stirring of revolution mixer.

In addition, it is preferable to remove agglomerates in the coating liquid after dispersion by a filter. By removing agglomerates with large particle sizes, the occurrence of streaks in the coating film can be suppressed.

The dispersion degree of the coating liquid is preferably a particle size measured by a particle size meter of 0.1 μm or more and 100 μm or less. The upper limit of the dispersion degree is more preferably a particle size of 80 μm or less, and still more preferably a particle size of 50 μm or less. If the particle size is less than 0.1 μm, the size is below the particle size of various material powders containing the positive electrode active material, and the material will be broken when the coating liquid is prepared, so it is not preferable. In addition, if the particle size is 100 μm or less, the coating can be stably applied without clogging or streaks of the coating film when the coating liquid is discharged.

The viscosity (ηb) of the coating solution of the positive electrode precursor is preferably 1,000 mPa. s above 20,000mPa. Below s, it is better to be 1,500mPa. s above 10,000mPa. Below s, further better is 1,700mPa. s above 5,000mPa. s below. If the viscosity (ηb) is 1,000mPa. Above s, dripping during the formation of the coating film is suppressed, and the width and thickness of the coating film can be well controlled. In addition, if it is 20,000mPa. Below s, the pressure loss of the coating liquid in the flow channel when using the coating machine can be applied stably, and it can be controlled below the desired coating film thickness.

In this embodiment, when the viscosity of the positive electrode coating solution is ηb ₁ and the viscosity after measuring ηb ₁ for 24 hours is ηb ₂ , ηb ₂ /ηb _{1 is} preferably 0.50 or more and 1.20 or less . If ηb ₂ /ηb ₁ is 0.50 or more, the uneven distribution of the binder in the coating liquid is suppressed, so that the peel strength of the positive electrode precursor can be improved, and the shedding of the positive electrode active material layer during pre-doping can be suppressed. If ηb ₂ /ηb ₁ is 1.20 or less, the modification of the binder in the coating liquid due to the alkali compound is suppressed, so the peel strength of the positive electrode precursor can be improved, and the positive electrode active material layer during pre-doping can be suppressed Fall off. Time of the positive electrode coating precursor generally required, mostly less than 1 per volume (Reel) electrode 24 hours so ηb evaluated by _1, and the viscosity was measured after ₁ ηb after 24 hours of ηb _2, to ensure coating The uniformity of the electrode state from the application start point to the application end point, such as the appearance or film thickness.

In this embodiment, the TI value (thixotropic index value) of the coating liquid is preferably 1.1 or more, more preferably 1.2 or more, and still more preferably 1.5 or more. If the TI value is 1.1 or more, the coating film width and thickness can be well controlled.

In this embodiment, when the thixotropic index value of the positive electrode coating solution is set to TI ₁ and the thixotropic index value after standing for 24 hours after measuring TI ₁ is set to TI ₂ , TI ₂ /TI ₁ is 0.50 or more and 1.20 or less. If TI ₂ /TI ₁ is 0.50 or more, dripping during electrode application can be suppressed, and by increasing the thickness of the positive electrode active material layer, a higher capacity can be achieved. If TI ₂ /TI ₁ is 1.20 or less, local thickening of the end of the positive electrode active material layer can be suppressed, and peeling of the positive electrode active material layer during pre-doping can be suppressed. Evaluation by TI _1, TI ₁ TI and measured after 24 hours after the value of TI _2, the starting point may be applied to ensure uniformity of the film thickness of the coating film or a pattern end portion of the end of the applicator.

The viscosity (ηb) and the TI value of this embodiment are respectively obtained according to the following methods. First, a stable viscosity (ηa) was obtained by measuring with an E-type viscometer under conditions of a temperature of 25° C. and a shear rate of 2 s ⁻¹ for 2 minutes or more. Next, the viscosity (ηb) was obtained by changing the shear rate to 20 s ^-1 and measuring under the same conditions as above. Using the viscosity value obtained above, the TI value is calculated according to the formula of TI value=ηa/ηb. When the shear rate is increased from 2s ^-1 to 20s ^-1 , the shear rate can be increased in one step, or the shear rate can be increased in multiple steps within the above range, and the shear rate can be appropriately obtained while The viscosity increases the shear rate. TI ₁ and ηb _{1 of} this implementation type use rotation. The orbital mixer disperses the coating liquid at a speed of 600 rpm for 1 minute, and is measured by the method described above. Next, the coating liquid was allowed to stand in a sealed state for 24 hours in a 25°C environment. After that, the values measured by the above method were TI ₂ and ηb _{2 again} . The weight of the positive electrode coating solution used for the measurement is not particularly limited, but it is preferably 10 g or more and 100 g or less from the viewpoint of reducing the deviation of the measurement. If the weight is 10 g or more, the reproducibility of the measurement can be ensured. If the weight is 100 g or less, the sample has excellent handleability.

[Manufacture of positive electrode precursor]

In this embodiment, the positive electrode precursor that becomes the positive electrode of the non-aqueous lithium electricity storage element can be manufactured by known electrode manufacturing techniques for lithium ion batteries, electric double layer capacitors, and the like. For example, the positive electrode precursor can be obtained by dispersing or dissolving the positive electrode active material, lithium compound other than the positive electrode active material, binder, and other optional components used as needed in water or an organic solvent to prepare a slurry A coating solution in a material form is applied to one or both surfaces of the positive electrode current collector to form a coating film, and this is dried. It is also possible to pressurize the obtained positive electrode precursor and adjust the thickness or bulk density of the positive electrode active material layer. Alternatively, the following method can also be used: dry mix the positive electrode active material, the lithium compound other than the positive electrode active material, and the binder, as well as any other ingredients used if necessary without using a solvent. After the obtained mixture is press-molded to produce a positive electrode sheet, the positive electrode sheet is attached to the positive electrode current collector using a conductive adhesive.

The method for forming the coating film of the positive electrode precursor is not particularly limited, and a die coater, a comma coater, and a knife coater can be suitably used. , Gravure coating machine and other coating machines. The coating film may be formed by a single-layer coating, or may be formed by a multi-layer coating. In the case of multi-layer coating, the composition of the coating liquid can also be adjusted so that the content of the alkali metal compound and/or lithium compound in each layer of the coating film is different. When the positive electrode current collector is coated with a coating film, multiple coatings, intermittent coatings, and multiple intermittent coatings are possible. In addition, it can be applied and dried on one side of the positive electrode current collector, and then sequentially coated and dried on the other side. It can also be applied on both sides of the positive electrode current collector and dried simultaneously. Both sides are coated simultaneously. When the coating liquid is applied to both surfaces of the positive electrode current collector, the individual ratios of the carbon material and the alkali metal compound on the surface and inside are preferably 10% or less. For example, the quality of the surface of the carbon material of the positive electrode current collector ratio A ₁ (table) and the inside of the A ₁ (li) ratio A ₁ (table) / A ₁ (li) 0.9 or more 1.1 or less. In addition, the thickness of the positive electrode active material layer on the surface and inside of the positive electrode current collector is preferably 10% or less. As the mass ratio and film thickness ratio of the surface and the inside are closer to 1.0, the less the charge-discharge load is concentrated on one side, the high-load charge-discharge cycle characteristics are improved.

In addition, in the TD direction of the positive electrode active material layer, it is preferable to make the end portion thinner than the center portion. When the electrode body described later is formed, the portion close to the terminal portion receives stress, so the positive electrode active material layer is likely to come off. Therefore, by making the positive electrode active material layer at the end thinner and easing the stress, the fall of the positive electrode active material layer can be suppressed. The thickness of the end portion is preferably in the direction of the TD of the positive electrode active material layer, and the thickness of the positive electrode active material layer within a range of 10% from the end to the center of the longest line of the positive electrode active material layer is the positive electrode active material The thickness of the positive electrode active material layer at the midpoint of the longest line segment of the layer is more than 90% and less than 100%.

The coating speed is preferably 0.1 m/min or more and 100 m/min or less, more preferably 0.5 m/min or more and 70 m/min or less, and still more preferably 1 m/min or more and 50 m/min or less. If the coating speed is 0.1 m/min or more, the coating can be performed stably. If the coating speed is 100 m/min or less, the coating accuracy can be sufficiently ensured.

The method for drying the coating film of the positive electrode precursor is not particularly limited, and drying methods such as hot air drying and infrared (IR) drying can be used. The coating film can be dried at a single temperature, The temperature can also be changed and dried in multiple stages. The coating film may be dried by combining several drying methods. The drying temperature is preferably 25°C or more and 200°C or less, more preferably 40°C or more and 180°C or less, and still more preferably 50°C or more and 160°C or less. If the drying temperature is above 25°C, the solvent in the coating film can be sufficiently volatilized. If the drying temperature is below 200°C, the coating film cracks caused by the rapid solvent evaporation, the uneven distribution of the binder caused by migration, and the oxidation of the positive electrode current collector or positive electrode active material layer can be suppressed.

The moisture contained in the positive electrode precursor after drying is preferably 100% or more and 10% or less of the mass of the positive electrode active material layer. If the moisture content is 0.1% or more, the deterioration of the adhesive caused by excessive drying can be suppressed, and the resistance can be reduced. If the moisture content is 10% or less, the deactivation of alkali metal ions in the non-aqueous lithium electricity storage element can be suppressed, and a higher capacity can be achieved.

The moisture contained in the positive electrode precursor can be measured, for example, according to the Karl-Fischer titration method (JIS 0068 (2001) "Moisture Measurement Method for Chemical Products").

The method of pressurizing the positive electrode precursor is not particularly limited, but a press machine that can use a hydraulic press machine, a vacuum press machine, or the like is more suitable. The thickness, bulk density, and electrode strength of the positive electrode active material layer can be adjusted by the pressurization pressure, the gap, and the surface temperature of the pressurization section described later.

The pressing pressure is preferably 0.5 kN/cm or more and 20 kN/cm or less, more preferably 1 kN/cm or more and 10 kN/cm or less, and still more preferably 2 kN/cm or more and 7 kN/cm or less. If the pressing pressure is 0.5 kN/cm or more, the electrode strength can be sufficiently improved. If the pressurizing pressure is 20 kN/cm or less, the cathode precursor rarely bends or wrinkles, and can be adjusted to the desired thickness and bulk density of the cathode active material layer.

As long as the person has ordinary knowledge in the technical field to which the present invention belongs, in order to obtain the desired thickness and bulk density of the positive electrode active material layer, the gap between the pressure rollers can be adjusted according to The thickness of the positive electrode precursor is set to an arbitrary value. Anyone with ordinary knowledge in the technical field to which the present invention belongs can set the pressurization speed to any speed at which the positive electrode precursor is less likely to bend and wrinkle.

The surface temperature of the pressurized part may be room temperature, and the pressurized part may be heated as needed. In the case of heating, the lower limit of the surface temperature of the pressurized part is preferably the melting point of the adhesive used minus 60°C or higher, more preferably the melting point of the adhesive minus 45°C or higher, and even more preferably the melting point of the adhesive minus 30 ℃ above. The upper limit of the surface temperature of the pressurized portion in the case of heating is preferably the melting point of the adhesive used plus 50°C or less, more preferably the melting point plus 30°C or less, and even more preferably the melting point of the adhesive plus 20°C or less. For example, when PVdF (polyvinylidene fluoride: melting point 150°C) is used as the binder, the surface temperature of the pressurized portion is preferably 90°C or more and 200°C or less, more preferably 105°C or more and 180°C or less, and still more The best line is above 120℃ and below 170℃. When the styrene-butadiene copolymer (melting point 100°C) is used as the binder, the surface temperature of the pressurized portion is preferably 40°C or more and 150°C or less, more preferably 55°C or more and 130°C or less, and still more preferably Department of 70 ℃ above 120 ℃ below.

The melting point of the adhesive can be obtained from the position of the endothermic peak of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, Inc., 10 mg of the sample resin is set in the measuring cell, and the temperature is 30°C at 10°C/min in a nitrogen atmosphere. When the heating rate is increased to 250°C, the endothermic peak temperature during the heating process is the melting point.

It is also possible to apply pressure several times while changing the conditions of the pressing pressure, gap, speed, and surface temperature of the pressing portion.

In the case of applying a plurality of positive electrode precursors, it is preferable to perform slitting before pressing. In the case where the positive electrode precursor coated with multiple strips is pressed without slitting, the current collector portion of the positive electrode active material layer is not coated It is subject to stress and wrinkles. In addition, the positive electrode precursor may be slit again after pressurization.

The thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less on each side of the positive electrode current collector. The thickness of the positive electrode active material layer is more preferably 25 μm or more and 100 μm or less, and even more preferably 30 μm or more and 80 μm or less. If the aforementioned thickness is 20 μm or more, a sufficient charge and discharge capacity can be exhibited. If the aforementioned thickness is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, while obtaining sufficient output characteristics, the cell volume can be reduced, so that the energy density can be improved. The upper and lower limits of the thickness range of the positive electrode active material layer may be combined arbitrarily. The thickness of the positive electrode active material layer in the case where the current collector has through holes or irregularities refers to the average value of the thickness of each side of the portion of the current collector without through holes or irregularities.

In the positive electrode precursor of this embodiment, the peel strength of the positive electrode active material layer is preferably 0.020 N/cm or more and 3.00 N/cm or less. If the peel strength is 0.020 N/cm or more, it is possible to suppress the shedding of the positive electrode active material layer caused by the gas generation in the pre-doping step, and to suppress the micro short circuit. If the peel strength is 3.00 N/cm or less, this means that there is no excess binder or the like in the positive electrode active material layer, so that the diffusibility of the electrolyte can be improved to achieve low resistance. The peel strength of the positive electrode active material layer is preferably 0.035 to 2.87 N/cm, and more preferably 0.070 to 2.56 N/cm.

The peel strength of the positive electrode active material layer is the value measured after the above-mentioned pressing; in the case of several pressings, it is the value measured after the final pressing; the electrode body described later is produced without pressing The situation is the value measured in the unpressurized state.

The peeling strength of the positive electrode active material layer can be measured by a known method, for example, using a peeling test that conforms to JIS Z0237 (2009) "Adhesive Tape, Adhesive Sheet Test Method", or, the ones used in the examples described later can be used experiment method.

In addition, the electrode body of the present embodiment is included in the positive electrode precursor described above, and if necessary, includes the negative electrode described later.

The dispersion degree of the present invention is a value obtained by performing a dispersion degree evaluation test with a particle size meter specified in JIS K5600. That is, for a particle size meter having a groove of a desired depth corresponding to the particle size, a sufficient amount of sample is flowed into the deeper bottom end of the groove and allowed to slightly overflow the groove. Next, make the long side of the scraper parallel to the width direction of the particle size meter, and put the blade edge of the scraper in contact with the deeper end of the groove of the particle size meter and place it, while keeping the scraper flat against the surface of the particle size meter and holding At a right angle and equal speed to the long side of the trench, scrape the surface of the particle size meter to the depth of the trench in 1 to 2 seconds, and illuminate and observe at an angle of 20° to 30° within 3 seconds after scraping. And read the depth of the particles in the groove of the particle size meter.

[positive electrode]

The bulk density of the positive electrode active material layer in the positive electrode after lithium doping is preferably 0.25 g/cm ³ or more, and more preferably 0.30 g/cm ³ or more and 1.3 g/cm ³ or less. If the bulk density of the positive electrode active material layer is 0.25 g/cm ³ or more, high energy density can be exhibited, and miniaturization of the power storage device can be achieved. If the bulk density is 1.3 g/cm ³ or less, the electrolyte in the pores in the positive electrode active material layer diffuses sufficiently, and high output characteristics can be obtained.

The average particle size of lithium compounds other than the positive electrode active material and the positive electrode active material

The positive electrode after lithium doping may also contain lithium compounds other than the positive electrode active material that is not decomposed during lithium doping. When the average particle diameter of the lithium compound other than the positive electrode active material is X ₁ and the average particle diameter of the positive electrode active material is Y ₁ , it is preferably 0.1 μm≦X ₁ ≦10 μm, 2 μm≦Y ₁ ≦20 μm, And X ₁ <Y ₁ , more preferably 0.5 μm≦X ₁ ≦5 μm, 3 μm≦Y ₁ ≦10 μm. If X ₁ is 0.1 μm or more, the high-load charge-discharge cycle characteristics are improved by adsorbing fluoride ions generated during the high-load charge-discharge cycle. When X ₁ is 10 μm or less, the reaction area with the fluoride ions generated during the high-load charge-discharge cycle increases, so that the fluoride ions can be efficiently adsorbed. When Y ₁ is 2 μm or more, electron conductivity between the positive electrode active materials can be ensured. In the case where Y ₁ is 20 μm or less, a high input-output characteristic can be exhibited due to an increase in the reaction area with electrolyte ions. In the case of X ₁ <Y ₁ , since lithium compounds other than the positive electrode active material are filled in the gap generated between the positive electrode active materials, it is possible to ensure the electron conductivity between the positive electrode active materials and increase the energy density.

The measurement methods of X ₁ and Y ₁ are not particularly limited, and can be calculated from the scanning electron microscope (SEM) image of the positive electrode profile and the scanning electron microscope/energy dispersive X-ray spectroscopy (SEM-EDX) image . For the method of forming the positive electrode cross section, for example, the following BIB (Broad Ion Beam) processing can be used: an Ar beam is irradiated from the upper part of the positive electrode, and a smooth cross section is made along the end of the shielding plate provided directly above the sample. When the positive electrode contains lithium carbonate, the distribution of carbonate ions can also be obtained by measuring the Raman imaging of the positive electrode profile.

(Identification method of lithium compounds other than positive electrode active material and positive electrode active material)

The lithium compound and the positive electrode active material can be determined by the oxygen mapping of the SEM-EDX image of the positive electrode profile measured at an observation magnification of 1,000 times to 4,000 times. The measurement method conditions of the SEM-EDX image are preferably no pixels with maximum brightness, and the brightness and contrast are adjusted to the average brightness value to enter the range of 40% to 60% brightness. For the obtained oxygen distribution graph, the particles including the bright part binarized on the basis of the average value of brightness of 50% or more of the area are regarded as lithium compounds other than the positive electrode active material.

(Calculation method of X ₁ and Y ₁ )

X ₁ and Y ₁ can be obtained by performing image analysis on the image obtained from the positive electrode cross-sectional SEM-EDX measured in the same visual field as the above-mentioned positive electrode cross-sectional SEM. The lithium compound particles X other than the positive electrode active material and the particles Y other than the positive electrode active material identified by the SEM image of the positive electrode cross-section described above are the X and Y observed in the cross-sectional SEM image For all the particles, the cross-sectional area S is obtained, and the particle diameter d calculated by the following formula (1) (the pi is set to π.) is obtained.

d=2×(S/π) ^1/2 type (1)

Using the determined particle diameter d, the volume average particle diameters X ₀ and Y ₀ are determined in the following formula (2).

X ₀ (Y ₀ )=Σ[4/3π×(d/2)] ³ ×d]/Σ[4/3π×(d/2)] ³ ] Equation (2)

The field of view of the positive electrode cross section was changed to measure 5 or more points, and the average value of X ₀ and Y _{0 was} defined as the average particle diameter X ₁ and Y ₁ .

The amount of lithium compounds other than the positive electrode active material contained in the positive electrode after lithium doping is based on the total mass of the positive electrode active material layer in the positive electrode, preferably 1% by mass or more and 50% by mass or less, more preferably 2.5% by mass Above 25% by mass or less. If the amount of the lithium compound is 1% by mass or more, the lithium compound other than the positive electrode active material suppresses the decomposition reaction of the electrolyte solvent on the positive electrode in a high-temperature environment, so the high-temperature durability is improved, and if it is 2.5% by mass or more, the effect becomes Notable. If the amount of the lithium compound other than the positive electrode active material is 50% by mass or less, since the electron conductivity between the positive electrode active materials is less likely to be hindered by the lithium compound other than the positive electrode active material, it exhibits high input and output characteristics. When it is 25% by mass or less, it is particularly preferable from the viewpoint of input/output characteristics. In addition, the lower limit and the upper limit can be arbitrarily combined.

<negative electrode>

The negative electrode has a negative electrode current collector and a negative electrode active material layer present on one or both sides of the negative electrode current collector.

[Anode Active Material Layer]

The negative electrode active material layer contains a negative electrode active material that can absorb and release alkali metal ions represented by lithium ions. In addition to the negative electrode active material, if necessary, it can also contain conductive fillers, binders, dispersion stabilizers, etc. Any ingredients.

[Anode Active Material]

As the negative electrode active material, a substance capable of storing and releasing alkali metal ions represented by lithium ions can be used. Specifically, carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin and tin compounds can be exemplified. The content of the carbon material relative to the total mass of the negative electrode active material is preferably 50% by mass or more, more preferably 70% by mass or more, or may be 100% by mass. From the viewpoint of obtaining a good effect of using in combination with other materials, the content rate of the carbon material with respect to the total mass of the negative electrode active material is, for example, preferably 90% by mass or less, or 80% by mass or less. The upper limit and lower limit of the range of the content rate of the above carbon material can be arbitrarily combined.

The negative electrode active material is preferably doped with lithium ions. In this specification, lithium ions doped in the negative electrode active material mainly include three types.

The first type is the lithium ions stored in advance in the negative electrode active material as design values before the production of the non-aqueous lithium storage element.

The second type is the lithium ions stored in the negative active material when the non-aqueous lithium storage element is manufactured and shipped.

The third type is a lithium ion stored in the negative electrode active material after the non-aqueous lithium storage element is used as the device.

By doping the negative electrode active material with lithium ions in advance, it becomes possible to well control the capacity and operating voltage of the obtained non-aqueous lithium power storage element.

Carbon materials, such as: hardly graphitizable carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; manufactured graphite; natural graphite; graphitized metastable carbon microspheres; graphite whiskers Amorphous carbonaceous materials such as acene-based substances; carbonaceous materials obtained by heat-treating carbonaceous material precursors; thermal decomposition products of furfuryl alcohol resins or novolak resins; fullerenes; carbon nanohorns; and this Etc. composite carbon materials. The precursor of the carbonaceous material is not particularly limited as long as it becomes a carbonaceous material by heat treatment, and examples include petroleum pitch, coal pitch, mesocarbon microbeads, coke, and synthetic resin (Eg phenol resin etc.) etc.

Among these, from the viewpoint of reducing the resistance of the negative electrode, it is preferably a composite carbon material in which one or more carbon materials (hereinafter also referred to as "substrate") coexist with a carbonaceous material precursor Heat treatment to make the composite carbon material of the base material and the carbonaceous material derived from the precursor of the carbonaceous material. It is also possible to mix the base material and the carbonaceous material precursor at a temperature higher than the melting point of the carbonaceous material precursor before heat treatment. The heat treatment temperature may be a temperature that allows the carbonaceous material precursor used to volatilize or thermally decompose to form a carbonaceous material, preferably 400°C or more and 2,500°C or less, more preferably 500°C or more and 2,000°C The following is more preferably 550°C or higher and 1,500°C or lower. The environment in which the heat treatment is performed is not particularly limited, and it is preferably a non-oxidizing environment.

Preferred examples of composite carbon materials are composite carbon materials 1 and 2 described below. You can choose to use any of these, or you can use both.

(Composite carbon material 1)

A carbon composite material, the carbon-based material one or more BET specific surface area of 100m ² / g or more 3,000m ² / g or less of the composite carbon material was used as the base. The substrate is not particularly limited, and activated carbon, carbon black, mold porous carbon, high specific surface area graphite, carbon nanoparticles, and the like can be suitably used.

Composite carbon material BET specific surface area of 1, the preferred system 100m ² / g or more 1,500m ² / g or less, more preferably Department of 150m ² / g or more 1,100m ² / g or less, further more preferably based 550m ² 180m ² / g or more /g or less. If the BET specific surface area is 100 m ² /g or more, the pores can be appropriately maintained, and the diffusion of lithium ions becomes good, so that high input-output characteristics can be exhibited. When the BET specific surface area is 1,500 m ² /g or less, the charge and discharge efficiency of lithium ions is improved, so there is no situation where the cycle durability is impaired. The upper limit and lower limit of the above range of the BET specific surface area of the composite carbon material 1 can be arbitrarily combined.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 1 is preferably 10% by mass or more and 200% by mass or less, more preferably 12% by mass or more and 180% by mass or less, and still more preferably 15% by mass or more and 160% by mass % Or less, 18% by mass or more and 150% by mass or less of the Tejia line. If the mass ratio of the carbonaceous material is 10% by mass or more, the micropores of the base material can be appropriately filled with the carbonaceous material, and the charge and discharge efficiency of lithium ions can be improved, so it can show good cycle durability. If the mass ratio of the carbonaceous material is 200% by mass or less, since the pores can be appropriately maintained and the diffusion of lithium ions becomes good, it can exhibit high input-output characteristics.

The amount of lithium ion doping per unit mass of the composite carbon material 1 is preferably 530 mAh/g or more and 2,500 mAh/g or less. More preferably, it is 620 mAh/g or more and 2,100 mAh/g or less, even more preferably 760 mAh/g or more and 1,700 mAh/g or less, and particularly preferably 840 mAh/g or more and 1,500 mAh/g or less. The upper and lower limits of the numerical range of lithium ion doping amount can be arbitrarily combined.

By doping lithium ions, the negative electrode potential becomes low. Therefore, when the negative electrode and the positive electrode including the composite carbon material 1 doped with lithium ions are combined, the voltage of the non-aqueous lithium power storage element becomes higher, and the utilization capacity of the positive electrode becomes larger. Therefore, the capacity and energy density of the obtained non-aqueous lithium electricity storage device become high.

If the doping amount is 530mAh/g or more, lithium ions can also be doped well The irreversible position of the lithium ion in the composite carbon material 1 cannot be detached once inserted, which can further reduce the amount of the composite carbon material 1 relative to the desired amount of lithium. Therefore, it becomes possible to make the thickness of the negative electrode thin and obtain a high energy density. The higher the doping amount, the lower the negative electrode potential, and the input/output characteristics, energy density, and durability are improved. If the doping amount is 2,500 mAh/g or less, there is no possibility of side effects such as precipitation of lithium metal.

As a preferred example of the composite carbon material 1, a composite carbon material 1a using activated carbon as a base material will be described.

For the composite carbon material 1a, the volume of pores derived from pores with a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V _m1 (cc/g), and those derived from pores with a diameter less than 20 Å calculated by the MP method When the micropore volume of the hole is V _m2 (cc/g), it is preferably 0.010≦V _m1 ≦0.300, 0.001≦V _m2 ≦0.650.

The amount of mesopores V _{m1 is more} preferably 0.010≦V _m1 ≦0.225, and even more preferably 0.010≦V _m1 ≦0.200. The amount of micropores V _{m2 is more} preferably 0.001≦V _m2 ≦0.200, further more preferably 0.001≦V _m2 ≦0.150, and particularly preferably 0.001≦V _m2 ≦0.100.

If the amount of mesopores V _m1 is 0.300 cc/g or less, in addition to increasing the BET specific surface area and increasing the doping amount of lithium ions, the bulk density of the negative electrode can also be increased. As a result, the negative electrode can be thinned. If the amount of micropores V _m2 is 0.650 cc/g or less, high charge and discharge efficiency for lithium ions can be maintained. If the mesopore volume V _m1 and the micropore volume V _m2 are above the lower limit (0.010≦V _m1 , 0.001≦V _m2 ), high input/output characteristics can be obtained.

Carbon composite material 1a of BET specific surface area, preferably based 100m ² / g or more 1,500m ² / g or less, more preferably Department of 150m ² / g or more 1,100m ² / g or less, further more preferably based 550m ² 180m ² / g or more /g or less. If the BET specific surface area is 100 m ² /g or more, the pores can be appropriately maintained, and the diffusion of lithium ions becomes good, so that high input-output characteristics can be exhibited. Since the doping amount of lithium ions can be increased, the negative electrode can be thinned. With a BET specific surface area of 1,500 m ² /g or less, the charge-discharge efficiency of lithium ions is improved, so that the cycle durability is less damaged.

The average pore diameter of the composite carbon material 1a is preferably at least 20Å, more preferably at least 25Å, and even more preferably at least 30Å from the viewpoint of high input-output characteristics. From the viewpoint of high energy density, the average pore diameter is preferably 65 Å or less, and more preferably 60 Å or less.

The average particle diameter of the composite carbon material 1a is preferably 1 μm or more and 10 μm or less. The lower limit is more preferably 2 μm or more, and still more preferably 2.5 μm or more. The upper limit is more preferably 6 μm or less, and still more preferably 4 μm or less. If the average particle size is 1 μm or more and 10 μm or less, good durability can be maintained.

The hydrogen atom/carbon atom atomic number ratio (H/C) of the composite carbon material 1a is preferably 0.05 or more and 0.35 or less, and more preferably 0.05 or more and 0.15 or less. In the case where H/C is below 0.35, the structure of the carbonaceous material (typically, polycyclic aromatic conjugated structure) covering the surface of the activated carbon develops well and the capacity (energy density) and charge-discharge efficiency change high. In the case where H/C is 0.05 or more, a good energy density can be obtained because there is no excessive carbonization. H/C is measured by an elemental analysis device.

The composite carbon material 1a has an amorphous structure derived from activated carbon of the substrate, but at the same time, it has a crystalline structure mainly derived from the coated carbonaceous material. According to the X-ray wide-angle diffraction method, the composite carbon material 1a preferably has a surface spacing d002 of (002) plane of 3.60 Å or more and 4.00 Å or less, and the crystallite size Lc in the c-axis direction obtained from the half-height width of the peak is 8.0 Those with Å above 20.0Å are more preferably those with d002 of 3.60Å above 3.75Å, and the c-axis crystallite size Lc obtained from the half-height width of the peak is 11.0Å above 16.0Å.

The activated carbon used as the base material of the composite carbon material 1a is not particularly limited as long as the obtained composite carbon material 1a exhibits desired characteristics. For example, commercially available products obtained from various raw materials such as petroleum-based, coal-based, plant-based, and polymer-based can be used. The average particle size of the activated carbon powder is preferably 1 μm or more and 15 μm or less, and more preferably 2 μm or more and 10 μm or less.

In order to obtain the composite carbon material 1a having the pore distribution range specified in the present embodiment, it is important that the pore distribution of the activated carbon used as the base material is.

In activated carbon, the amount of pores derived from pores with a diameter of 20Å to 500Å calculated by the BJH method is V ₁ (cc/g), and pores with a diameter of less than 20Å calculated by the MP method When the amount of micropores is V ₂ (cc/g), it is preferably 0.050≦V ₁ ≦0.500, 0.005≦V ₂ ≦1.000, and 0.2≦V ₁ /V ₂ ≦20.0.

Regarding the amount of mesopores V ₁ , it is more preferably 0.050≦V ₁ ≦0.350, and even more preferably 0.100≦V ₁ ≦0.300. Regarding the micropore volume V ₂ , it is more preferably 0.005≦V ₂ ≦0.850, and even more preferably 0.100≦V ₂ ≦0.800. The ratio of the amount of mesopores/micropores is more preferably 0.22≦V ₁ /V ₂ ≦15.0, and even more preferably 0.25≦V ₁ /V ₂ ≦10.0. In the case where the pore volume V ₁ of the activated carbon is 0.500 or less and the pore volume V ₂ is 1.000 or less, in order to obtain the fine pore structure of the composite carbon material 1a, it is only necessary to cover the appropriate amount of carbonaceous material, so it becomes easy Control pore structure. The activated carbon may have a pore volume V ₁ of 0.050 or more, a micro pore volume V ₂ of 0.005 or more, a V ₁ /V ₂ of 0.2 or more, and a V ₁ /V ₂ of 20.0 or less. The pore structure of the composite carbon material 1a can be easily obtained.

The carbonaceous material precursor used as the raw material of the composite carbon material 1a is preferably an organic material that can make the carbonaceous material cover the activated carbon by heat treatment and dissolve in solid, liquid, or solvent. Examples of the carbonaceous material precursors include pitch, mesophase carbon microspheres, coke, and synthetic resins, such as furfuryl alcohol resins, phenol resins, and the like. Of these carbonaceous material precursors, cheap ones are used Asphalt is better in manufacturing cost. Asphalt can be roughly divided into petroleum-based asphalt and coal-based asphalt. Examples of petroleum-based pitches include distillation residues of crude oil, cracking residues of fluidized catalysts (decant oil, etc.), sink bottom oils derived from thermal crackers, and ethylene tar obtained during the cracking of light oils.

In the case of using asphalt, for example, by performing heat treatment in the presence of asphalt and activated carbon, thermally reacting the volatile components or thermal decomposition components of the asphalt on the surface of the activated carbon to coat the carbonaceous material with the activated carbon to obtain a composite Carbon material 1a. In this case, the volatile components or thermal decomposition components of the asphalt are coated into the pores of the activated carbon at a temperature of about 200 to 500°C, and the reaction of the coated components into a carbonaceous material is performed at a temperature above 400°C. The peak temperature (maximum reaching temperature) during heat treatment is appropriately determined according to the characteristics, thermal reaction type, thermal reaction environment, etc. of the obtained composite carbon material 1a, preferably 400°C or higher, more preferably 450°C to 1,000 ℃, further preferably 500 ~ 800 ℃. The time for maintaining the peak temperature during the heat treatment is preferably 30 minutes to 10 hours, more preferably 1 hour to 7 hours, and still more preferably 2 hours to 5 hours. For example, when the heat treatment is performed at a peak temperature of about 500 to 800°C for 2 hours to 5 hours, the carbonaceous material coated on the surface of the activated carbon becomes a polycyclic aromatic hydrocarbon.

The softening point of asphalt is preferably 30°C or more and 250°C or less, and more preferably 60°C or more and 130°C or less. Asphalt with a softening point above 30°C will not hinder operability and can be loaded with good accuracy. Asphalt with a softening point below 250°C contains more low-molecular compounds, so if asphalt is used, even the fine pores in the activated carbon can be covered.

A specific method for manufacturing the composite carbon material 1a may be, for example, a method of heat-treating activated carbon in an inert environment containing hydrocarbon gas volatilized from the precursor of the carbonaceous material, and coating the carbonaceous material in the gas phase. It is also possible to adopt a method of pre-mixing activated carbon and a carbonaceous material precursor for heat treatment, or applying a carbonaceous material precursor dissolved in a solvent to the activated carbon And after drying, heat treatment method.

The mass ratio of the carbonaceous material to the activated carbon in the composite carbon material 1a is preferably 10% by mass or more and 100% by mass or less, and more preferably 15% by mass or more and 80% by mass or less. If the mass ratio of the carbonaceous material is more than 10% by mass, the pores of the activated carbon can be properly filled with the carbonaceous material, which improves the charge and discharge efficiency of lithium ions, so the cycle durability is less damaged . If the mass ratio of the carbonaceous material is 100% by mass or less, the pores of the composite carbon material 1a are appropriately maintained and the specific surface area is maintained in a relatively large state. Therefore, as a result of increasing the doping amount of lithium ions, even if the negative electrode is thinned, high output density and high durability can be maintained.

(Composite carbon material 2)

The composite carbon material 2 is a composite carbon material using one or more carbon materials having a BET specific surface area of 0.5 m ² /g or more and 80 m ² /g or less as a substrate. The substrate is not particularly limited, and natural graphite, artificial graphite, low-crystalline graphite, hard carbon, soft carbon, carbon black, etc. can be suitably used.

The BET specific surface area of the composite carbon material 2 is preferably 1 m ² /g or more and 50 m ² /g or less, more preferably 1.5 m ² /g or more and 40 m ² /g or less, and still more preferably 2 m ² /g or more and 25 m ² / g or less. If the BET specific surface area is 1 m ² /g or more, since a reaction field with lithium ions can be sufficiently secured, high input-output characteristics can be exhibited. If the BET specific surface area is 50 m ² /g or less, the charge and discharge efficiency of lithium ions is improved, and the decomposition reaction of the non-aqueous electrolyte during charge and discharge is suppressed, so high cycle durability can be exhibited. The upper and lower limits of the BET specific surface area range of the composite carbon material 2 can be arbitrarily combined.

The average particle diameter of the composite carbon material 2 is preferably 1 μm or more and 10 μm or less. The average particle size is more preferably 2 μm or more and 8 μm or less, and still more preferably 3 μm or more and 6 μm or less. If the average particle size is 1 μm or more, the charge and discharge efficiency of lithium ions is improved, so it can show high cycle durability Sex. If the average particle diameter is 10 μm or less, since the reaction area of the composite carbon material 2 and the non-aqueous electrolyte increases, it can exhibit high input-output characteristics.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 2 is preferably 1% by mass or more and 30% by mass or less, more preferably 1.2% by mass or more and 25% by mass or less, and still more preferably 1.5% by mass or more and 20% by mass %the following. If the mass ratio of the carbonaceous material is 1% or more by mass, the reaction position with lithium ions can be sufficiently increased by the carbonaceous material, and the desolvation of lithium ions becomes easy, so it can show high input and output characteristic. If the mass ratio of the carbonaceous material is 20% by mass or less, since lithium ions can be well diffused in the solid between the carbonaceous material and the base material, high input-output characteristics can be exhibited. Since the charge and discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

The amount of lithium ion doping per unit mass of the composite carbon material 2 is preferably 50 mAh/g or more and 700 mAh/g or less, more preferably 70 mAh/g or more and 650 mAh/g or less, and even more preferably 90 mAh/g or more and 600 mAh/g Below, the ultra good system is 100 mAh/g or more and 550 mAh/g or less. The upper and lower limits of the range of lithium ion doping amount of the composite carbon material 2 can be arbitrarily combined.

By doping lithium ions, the negative electrode potential becomes low. Therefore, when the negative electrode and the positive electrode including the composite carbon material 2 doped with lithium ions are combined, the voltage of the non-aqueous lithium power storage element becomes higher, and the utilization capacity of the positive electrode becomes larger. Therefore, the capacity and energy density of the obtained non-aqueous lithium electricity storage device become high.

If the doping amount is 50 mAh/g or more, lithium ions can be well doped in the irreversible position where the lithium ions in the composite carbon material 2 cannot be detached once inserted, so a high energy density can be obtained. The higher the doping amount, the lower the negative electrode potential, and the input/output characteristics, energy density, and durability are improved.

If the doping amount is 700 mAh/g or less, there is little concern about side effects such as precipitation of lithium metal.

As a preferred example of the composite carbon material 2, a composite carbon material 2a using a graphite material as a base material will be described.

The average particle diameter of the composite carbon material 2a is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and still more preferably 3 μm or more and 6 μm or less. If the average particle size is 1 μm or more, since the charge and discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited. If it is 10 μm or less, since the reaction area of the composite carbon material 2 a and the non-aqueous electrolyte increases, it can exhibit high input-output characteristics.

The BET specific surface area of the composite carbon material 2a is preferably 1 m ² /g or more and 20 m ² /g or less, and more preferably 1 m ² /g or more and 15 m ² /g or less. If the BET specific surface area is 1 m ² /g or more, since the reaction field with lithium ions can be sufficiently secured, high input-output characteristics can be exhibited. If it is 20 m ² /g or less, the charge and discharge efficiency of lithium ions is improved, and the decomposition reaction of the non-aqueous electrolyte during charge and discharge is suppressed, so high cycle durability can be exhibited.

The graphite material used as the base material is not particularly limited as long as the obtained composite carbon material 2a exhibits desired characteristics. For example, artificial graphite, natural graphite, graphitized metastable carbon microspheres, graphite whiskers, etc. can be used. The average particle size of the graphite material is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 8 μm or less.

The carbonaceous material precursor used as the raw material of the composite carbon material 2a is preferably an organic material that can be compounded with graphite materials by heat treatment and can be dissolved in solid, liquid, or solvent. Examples of the precursor of the carbonaceous material include pitch, mesophase carbon microspheres, coke, and synthetic resins, such as furfuryl alcohol resin, phenol resin, and the like. Of these carbonaceous material precursors, cheap to use The asphalt is better in manufacturing cost. Asphalt can be roughly divided into petroleum-based asphalt and coal-based asphalt. Examples of petroleum-based pitches are: distillation residues of crude oil, residues of fluidized catalyst cracking (clarified oil, etc.), bottom oil from thermal crackers, ethylene tar obtained during cracking of light oil, etc.

The mass ratio of the carbonaceous material to the graphite material in the composite carbon material 2a is preferably 1% by mass or more and 10% by mass or less, more preferably 1.2% by mass or more and 8% by mass or less, and still more preferably 1.5% by mass or more and 6% by mass % Or less, 2% by mass or more and 5% by mass or less. If the mass ratio of the carbonaceous material is 1% by mass or more, the reaction position with lithium ions can be sufficiently increased by the carbonaceous material, and the desolvation of lithium ions becomes easy, so it can show high input and output characteristic. If the mass ratio of the carbonaceous material is 20% by mass or less, since the lithium ions can be well diffused in the solid between the carbonaceous material and the graphite material, high input-output characteristics can be exhibited. Since the charge and discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

The carbon composite material 1c BET specific surface area, preferably based 100m ² / 350m ² g or more / g or less, more preferably Department of 150m ² / g or more 300m ² / g or less. If the BET specific surface area is 100 m ² /g or more, the amount of alkali metal ion pre-doping can be sufficiently increased, so that the negative electrode active material layer can be thinned. In addition, when the BET specific surface area is 350 m ² /g or less, the coatability of the negative electrode active material layer is excellent.

Composite carbon material, using lithium metal as the counter electrode, at a measurement temperature of 25°C, constant current charging at a current value of 0.5 mA/cm ² until the voltage value reaches 0.01 V, and then constant voltage charging until the current value reaches 0.01 mA/cm The first charging capacity at ² o'clock is preferably 300 mAh/g or more and 1,600 mAh/g or less per unit mass of the aforementioned composite carbon material, more preferably 400 mAh/g or more and 1,500 mAh/g or less, and even more preferably 500 mAh/g or more and 1,450 mAh. /g or less. If the first charge capacity is 300 mAh/g or more, the pre-doping amount of alkali metal ions can be sufficiently increased, so that even when the negative electrode active material layer is thinned, it can have high output characteristics. In addition, if the first charge capacity is 1,600mAh/g or less, the aforementioned composite carbon material is doped. The swelling of the aforementioned composite carbon material when dedoping alkali metal ions. The shrinkage becomes smaller, and the strength of the negative electrode is maintained.

The composite carbon material 1c described above is a composite porous material satisfying the following conditions (1) and (2) from the viewpoint of obtaining a good internal resistance value.

(1) The mesopore volume (the amount of pores with a diameter of 2 nm or more and 50 nm or less) Vm ₁ (cc/g) is calculated by the aforementioned BJH method, which satisfies the condition of 0.01≦Vm ₁ <0.10.

(2) The amount of micropores (the amount of pores with a diameter less than 2 nm) Vm ₂ (cc/g) calculated by the aforementioned MP method satisfies the condition of 0.01≦Vm ₂ <0.30.

The negative electrode active material is preferably in the form of particles.

The particle diameter of the silicon, silicon oxide, silicon alloy and silicon compound, and tin and tin compound is preferably 0.1 μm or more and 30 μm or less. If the particle size is 0.1 μm or more, the contact area with the electrolyte increases, and the resistance of the non-aqueous lithium electricity storage element can be reduced. In addition, if the particle size is 30 μm or less, it is caused by the doping of the alkali metal ions of the negative electrode with charge and discharge. The swelling of the dedoped negative electrode. The shrinkage becomes smaller, and the strength of the negative electrode is maintained.

The aforementioned silicon, silicon oxide, silicon alloy and silicon compound, and tin and tin compound can be micronized by pulverization using a jet mill built in a classifier, agitated ball mill, or the like. The pulverizer is equipped with a centrifugal force classifier, which can use a cyclone or a dust collector to capture fine particles crushed in an inert gas environment such as nitrogen or argon.

The content ratio of the negative electrode active material in the negative electrode active material layer of the negative electrode precursor, based on the total mass of the negative electrode active material layer, is preferably 70% by mass or more, and more preferably 80% by mass or more.

[Any component of the negative electrode active material layer]

In addition to the negative electrode active material, the negative electrode active material layer of this embodiment type may be Contains any components such as conductive fillers, binders, dispersion stabilizers, etc.

The type of conductive filler is not particularly limited, and examples include acetylene black, Ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, and mixtures of these. The amount of conductive filler used is preferably more than 0 parts by mass and 30 parts by mass or less, more preferably more than 0 parts by mass and 20 parts by mass or less, and even more preferably more than 0 parts by mass and 15 parts by mass relative to 100 parts by mass of the negative electrode active material. Below.

The binder is not particularly limited, for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyacrylic acid, polyimide, latex, styrene-butadiene copolymer, fluororubber , Acrylic copolymer, etc. Among them, polyacrylic acid is suitable as a binder contained in the positive electrode active material layer for the same reason as described above, and it is possible to obtain a negative electrode that does not swell with the non-aqueous electrolyte and does not decrease in mechanical strength even when stored at high temperature.

The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less relative to 100 parts by mass of the negative electrode active material, more preferably 2 parts by mass or more and 27 parts by mass or less, and still more preferably 3 parts by mass or more and 25 parts by mass. the following. If the amount of the binder is 1 part by mass or more, sufficient electrode strength is exhibited. If the amount of the binder is 30 parts by mass or less, it will not hinder lithium ions from entering and exiting the negative electrode active material, and will exhibit high input-output characteristics.

The mixing amount of the conductive filler in the negative electrode active material layer is preferably 20 parts by mass or less relative to 100 parts by mass of the negative electrode active material, and more preferably 1 to 15 parts by mass. Although the conductive filler is preferably mixed in the negative electrode active material layer from the viewpoint of high input, but if the mixing amount is more than 20 parts by mass, the content of the negative electrode active material in the negative electrode active material layer becomes smaller, and the volume per volume The reduced energy density is therefore less favorable.

The amount of binder used in the negative electrode active material layer is relative to 100 parts by mass of the negative electrode active material, It is preferably 3 to 25 parts by mass, and more preferably 5 to 20 parts by mass. When the amount of the binder is less than 3 parts by mass, sufficient adhesion between the current collector and the negative electrode active material layer in the negative electrode (precursor) cannot be ensured, and the interface resistance between the current collector and the active material layer increases. On the other hand, in the case where the amount of the binder is greater than 25 parts by mass, the binder excessively covers the surface of the active material of the negative electrode (precursor), and the diffusion resistance of ions in the pores of the active material increases.

The dispersion stabilizer is not particularly limited, and for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), cellulose derivatives and the like can be used. The amount of the dispersion stabilizer used is preferably 0 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the negative electrode active material. If the amount of the dispersion stabilizer is 10 parts by mass or less, the input and output characteristics of lithium ions to the negative electrode active material are not hindered, and high input-output characteristics are exhibited.

[Negative current collector]

The material constituting the negative electrode current collector of this embodiment is preferably a metal foil that has high electron conductivity and is less likely to cause degradation due to elution of the non-aqueous electrolyte and reaction with the electrolyte or ions. Such metal foil is not particularly limited, and examples include aluminum foil, copper foil, nickel foil, and stainless steel foil. The negative electrode current collector of the non-aqueous lithium electricity storage element of this embodiment is preferably a copper foil.

The metal foil may be a metal foil without bumps, through holes, etc., or a metal foil with bumps, such as embossing, chemical etching, electrolysis, spraying, etc., or a porous metal mesh, Metal foil with through holes such as perforated metal and etched foil.

Among them, the negative electrode current collector of this embodiment is preferably a metal foil without through holes. Those without through-holes have lower manufacturing costs, and can contribute to higher energy density because they are easy to be thinned. Since they can reduce the current collector resistance, they can achieve high input and output characteristics.

The thickness of the negative electrode current collector, as long as the shape and strength of the negative electrode can be sufficiently maintained and There is no particular limitation, for example, it is preferably 1 to 100 μm.

[Manufacture of negative electrode]

The negative electrode has a negative electrode active material layer on one side or both sides of the negative electrode current collector. In a typical aspect, the negative electrode active material layer is fixed to the negative electrode current collector.

The negative electrode can be manufactured by a known manufacturing technique of electrodes such as lithium ion batteries and electric double layer capacitors. For example, the negative electrode can be obtained by dispersing or dissolving various materials including the negative electrode active material in water or an organic solvent to prepare a slurry-like negative electrode coating solution, and applying the negative electrode coating solution to the negative electrode collector Form a coating on one or both sides of the body and dry it. The obtained negative electrode may be further pressurized to adjust the thickness or bulk density of the negative electrode active material layer. Alternatively, the following method can also be used: without using a solvent, various materials containing the negative electrode active material are dry mixed, the obtained mixture is press-molded, and then attached to the negative electrode current collector using a conductive adhesive .

The preparation of the negative electrode coating solution, the formation of the negative electrode coating film, and drying, and the optional pressurization, respectively, can be used as described above for the preparation of the positive electrode coating solution, the formation of the positive electrode coating film, drying, and adding It can be implemented by the same method, or it can be implemented after appropriate changes are made to those who have ordinary knowledge in the technical field to which this invention belongs. The viscosity (ηb) and thixotropic index (TI) values of the negative electrode coating solution may be the same as the positive electrode coating solution.

The thickness of the negative electrode active material layer on each side is preferably 5 μm or more and 100 μm or less, the lower limit, more preferably 7 μm or more, still more preferably 10 μm or more, and the upper limit, more preferably 80 μm or less, and still more preferably 60 μm. the following. If the thickness of the negative electrode active material layer is 5 μm or more on each side, streaks and the like do not easily occur when the negative electrode active material layer is applied, and the coating properties are excellent. If the thickness of the negative electrode active material layer is 100 μm or less on each side, by reducing the cell volume, high Energy Density. The thickness of the negative electrode active material layer in the case where the negative electrode current collector has through holes, irregularities, etc. refers to the average value of the thickness of each side of the portion of the negative electrode current collector that does not have through holes and irregularities.

The bulk density of the negative electrode active material layer is preferably 0.30 g/cm ³ or more and 1.8 g/cm ³ or less, more preferably 0.40 g/cm ³ or more and 1.5 g/cm ³ or less, and even more preferably 0.45 g/cm ³ or more. 1.3g/cm ³ or less. If the bulk density is 0.30 g/cm ³ or more, sufficient electrical conductivity between the negative electrode active materials can be exhibited while maintaining sufficient strength. If it is 1.8 g/cm ³ or less, the pores in which the ions can sufficiently diffuse in the negative electrode active material layer can be ensured.

<Non-aqueous electrolyte>

In the non-aqueous lithium electricity storage device of this embodiment, the electrolyte is a non-aqueous electrolyte. That is, the electrolyte contains an organic solvent (non-aqueous solvent). The non-aqueous electrolyte contains a lithium salt electrolyte. That is, the non-aqueous electrolyte contains lithium ions derived from the lithium salt electrolyte as the electrolyte.

For the non-aqueous electrolyte of this embodiment type, when aluminum foil is used as the working electrode and lithium metal is used as the counter electrode and the reference electrode to obtain a cyclic voltammogram, 3.8V (vs. Li/Li ⁺ ) or more and 4.8V (vs .Li/Li ⁺ ) The maximum reaction current value in the voltage range below is 0.010 mA/cm ² or less with respect to the area of the aluminum foil. This value is preferably 0.008 mA/cm ² or less, more preferably 0.005 mA/cm ² or less, and still more preferably 0.003 mA/cm ² or less.

In this embodiment, it is preferable to decompose the lithium compound in the positive electrode precursor and apply lithium to the negative electrode by applying a voltage between the positive electrode precursor and the negative electrode. At this time, for example, in the case of using aluminum foil as the positive electrode current collector, the aluminum foil of the positive electrode current collector is oxidized and eluted due to the application of a high voltage to the positive electrode precursor, especially the exposed portion of the aluminum foil not coated with the positive electrode active material layer is corroded possibility. If the aluminum foil is corroded, the internal resistance of the electricity storage element rises, and the worst case is that the positive electrode current collector is broken and can no longer be used as an electricity storage element. In particular, it tends to corrode easily at high temperatures and when high voltage is applied, which affects not only the lithium doping, but also the high-temperature durability of the completed storage element. The above-mentioned dissolution reaction of the positive electrode current collector depends on the composition of the non-aqueous electrolyte. For the cyclic voltammogram of the above non-aqueous electrolyte, if the maximum reaction current value in the voltage range of 3.8 V or more and 4.8 V or less under the Li/Li ⁺ ratio is 0.010 mA/cm ² or less, the accompanying positive electrode set can be suppressed Corrosion caused by the elution of the electrical body, and the resulting increase in resistance, disconnection of the current collector, etc., so that while high input and output characteristics can be obtained, high temperature durability is also excellent.

[Lithium salt]

Examples of the lithium salt include lithium salts having an amide imine structure and other lithium salts.

Examples of lithium salt electrolytes having an amide imide structure include lithium bis(fluorosulfonyl)imide [LiN(SO ₂ F) ₂ , abbreviation: LiFSI], lithium bis(trifluoromethanesulfonyl)imide[ LiN(SO ₂ CF ₃ ) ₂ , abbreviation: LiTFSI], lithium bis(pentafluoroethanesulfonyl)imide [LiN(SO ₂ C ₂ F ₅ ) ₂ , abbreviation: LiBETI], LiN(SO ₂ CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN(SO ₂ CF ₃ )(SO ₂ C ₂ F ₄ H), etc.; Other lithium salts can be exemplified by: LiC(SO ₂ F) ₃ , LiC(SO ₂ CF ₃ ) ₃ , LiC(SO ₂ C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF ₄ , LiF ₂ BC ₂ O ₄ and so on. These can be used alone or in combination of two or more. Among them, from the viewpoint that the non-aqueous lithium electricity storage device exhibits high input-output characteristics and can have high durability under high-temperature storage, it is preferable to include a lithium salt having an amide imide structure, even in a low-temperature environment In terms of high conductivity, it is better to include LiN(SO ₂ F) ₂ . In addition, LiPF ₆ , LiBF ₄ , and LiF ₂ BC ₂ O ₄ generate fluoride ions through decomposition, and it is easy to form a film on the surface of the aluminum foil, which can further suppress the corrosion of the positive electrode current collector. Wait for more than one.

Among the lithium salts with an imide structure, the following lithium salts also exist: if used alone, the corrosion of the positive electrode current collector such as aluminum foil is high, and the withstand voltage becomes low (in the voltage range of 3.8V or more and 4.8V or less The maximum reaction current value becomes higher). In this case, it is preferable to use a lithium salt (for example, LiF ₂ BC ₂ O ₄ ) that generates fluoride ions by decomposition to easily form a film on the surface of the aluminum foil, and additives described later.

The total concentration of the lithium salt electrolyte in the non-aqueous electrolyte is based on the total amount of the non-aqueous electrolyte, preferably 0.5 mol/L or more, and more preferably 0.5 mol/L or more and 2.0 mol/L or less. If the concentration of the lithium salt electrolyte is 0.5 mol/L or more, the capacity of the electricity storage element can be sufficiently increased because the anions are sufficiently present. In the case where the concentration of the lithium salt electrolyte is 2.0 mol/L or less, the undissolved lithium salt can be prevented from being precipitated into the non-aqueous electrolyte, and the viscosity of the electrolyte becomes too high, the conductivity does not decrease, and the output characteristics are also It is better not to lower it.

Examples of the non-aqueous solvent contained in the non-aqueous electrolyte of the present embodiment include cyclic carbonate and chain carbonate.

Examples of the cyclic carbonates include olefin carbonate compounds represented by ethyl carbonate, propylene carbonate, butylene carbonate, and the like. Alkenyl carbonate compounds are typically unsubstituted.

Examples of the chain carbonates include dialkyl carbonate compounds represented by dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, and dibutyl carbonate. The dialkyl carbonate compound is typically unsubstituted. Among them, from the viewpoint of durability under high-temperature storage, it is preferable not to use dimethyl carbonate having a low boiling point and poor heat resistance. In addition, ethylidene carbonate forms a protective film on the surface of the negative electrode after reduction decomposition, and a non-aqueous lithium electric storage element having excellent durability at high temperature and high voltage can be obtained, which is preferable. Propylene carbonate is preferred because of its low melting point, which does not easily cause solidification of the non-aqueous electrolyte in a low-temperature environment or precipitation of non-aqueous solvent components. In the case of mixed use of ethyl carbonate and propylene carbonate, in order to effectively exert the protective film forming ability of ethyl carbonate to the surface of the negative electrode, it is preferable to contain more carbonate than propylene carbonate. Ethyl ester.

The non-aqueous solvent of this embodiment preferably contains both cyclic carbonate and chain carbonate. The non-aqueous electrolyte contains cyclic carbonate and chain carbonate, which is advantageous in terms of dissolving a lithium salt at a desired concentration and a point exhibiting high lithium ion conductivity.

The total content of cyclic carbonate and chain carbonate is based on the total mass of the non-aqueous electrolyte, preferably 50% by mass or more, more preferably 65% by mass or more; preferably 95% by mass or less, more preferably Department of 90% by mass or less. If the total content of the cyclic carbonate and the chain carbonate is 50% by mass or more, the lithium salt of the desired concentration is easily dissolved, and high lithium ion conductivity can be exhibited. If it is 95% by mass or less, the electrolyte, It becomes easy to further contain additives described later. The upper and lower limits of the above total concentration range can be combined arbitrarily.

[additive]

The non-aqueous electrolyte may further contain additives. The additive is not particularly limited, and examples include: selected from sultone compounds, cyclic phosphazenes, acyclic fluorine-containing ethers, fluorine-containing cyclic carbonates represented by fluoroethylene carbonate (FEC), and Vinyl carbonate (VC) is at least one member selected from the group consisting of cyclic carbonate, cyclic carboxylic acid ester, and cyclic acid anhydride. One type of these additives may be used alone, or two or more types may be used in combination. Among them, the non-cyclic fluorinated ethers of fluorinated compounds, cyclic fluorinated carbonates, and cyclic fluorinated phosphazenes generate fluoride ions by decomposition, and it is easy to form a film on the surface of the aluminum foil, which can further suppress the positive electrode collection The corrosion of the electrical body is therefore preferred.

Examples of non-cyclic fluorinated ethers: HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₂ CF ₂ CF ₂ H, HCF ₂ CF ₂ CH ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₂ CF ₂ CFHCF _3, etc. Among them, from the viewpoint of electrochemical stability, HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H is preferred.

The content of the non-cyclic fluorine-containing ether is based on the total mass of the above-mentioned non-aqueous electrolyte, preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less. If the content of the non-cyclic fluorine-containing ether is 0.5% by mass or more, the stability of the non-aqueous electrolyte solution to oxidative decomposition is improved, and a storage element with high durability at high temperatures can be obtained. If the content of the non-cyclic fluorinated ether is 15% by mass or less, the solubility of the electrolyte salt is kept good, and the ionic conductivity of the non-aqueous electrolyte can be maintained to be high, so that a high degree of input-output characteristics can be exhibited.

Acyclic fluorinated ethers can be used alone or in combination of two or more.

The cyclic fluorocarbonate is preferably selected from the group consisting of fluoroethylene carbonate (FEC) and difluoroethylene carbonate (dFEC) in terms of compatibility with other non-aqueous solvents. One kind.

The content of the cyclic fluorine-containing carbonate is based on the total mass of the non-aqueous electrolyte solution, preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less. If the content of the cyclic fluorine-containing carbonate is 0.5% by mass or more, a good-quality coating can be formed on the negative electrode to suppress the reductive decomposition of the electrolytic solution on the negative electrode, thereby obtaining a high-temperature durable storage device with high temperature . If the content of the cyclic fluorine-containing carbonate is 10% by mass or less, the solubility of the electrolyte salt is kept good, and a high ion conductivity of the non-aqueous electrolyte can be maintained, so that it becomes possible to exhibit high input-output characteristics .

The cyclic fluorine-containing carbonate may be used alone or in combination of two or more.

Cyclic fluorine-containing phosphazene, for example: ethoxy pentafluorocyclotriphosphazene, diethoxytetrafluorocyclotriphosphazene, phenoxy pentafluorocyclotriphosphazene, etc., preferably selected from these More than one of them.

The content of cyclic fluorinated phosphazene in non-aqueous electrolyte is based on the above non-aqueous electrolysis The total mass of the liquid is used as a reference, preferably 0.5 mass% to 20 mass%. If the content rate is 0.5% by mass or more, it becomes possible to suppress decomposition of the electrolyte at high temperature and suppress gas generation. If the content rate is 20% by mass or less, the decrease in the ionic conductivity of the electrolyte can be suppressed, and high input-output characteristics can be maintained. For the above reasons, the content of the cyclic fluorine-containing phosphazene is more preferably 2% by mass or more and 15% by mass or less, and still more preferably 4% by mass or more and 12% by mass or less.

The cyclic fluorine-containing phosphazene may be used alone, or two or more kinds may be used in combination.

[Electrolyte containing alkali metal salt]

In this embodiment, the electrolyte solution containing an alkali metal salt is a non-aqueous electrolyte solution. That is, the electrolyte contains a non-aqueous solvent. The non-aqueous electrolyte contains 0.5 mol/L or more alkali metal salt based on the total amount of the non-aqueous electrolyte. That is, the non-aqueous electrolyte contains an alkali metal salt as an electrolyte. The non-aqueous solvent contained in the non-aqueous electrolyte can be exemplified by cyclic carbonates represented by ethyl carbonate, propylene carbonate, etc., dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc. Representative chain carbonate. From the viewpoint of suppressing the increase in resistance under an environment of 85° C. or higher, it is preferable to make the electrolyte composition such that the Hansen solubility parameter RED value for the binder is greater than 1.

The electrolyte salt containing alkali metal ions dissolved in the non-aqueous solvent as described above, for example, can be used: MFSI, MBF ₄ , MPF ₆ , MClO ₄ etc. where M is Li, Na, K, Rb or Cs. From the viewpoint of suppressing the increase in resistance in a high-temperature environment, MFSI, MBF ₄ , or MClO ₄ or mixed electrolyte salts of these can be suitably used.

The non-aqueous electrolyte of the present embodiment only needs to contain at least one or more alkali metal ions, or two or more alkali metal salts, and may also contain alkali metal salts and be selected from beryllium salts, magnesium salts, and calcium salts. , Alkaline earth metal salts of strontium and barium salts. In the case where the non-aqueous electrolyte contains more than two alkali metal salts, the cations with different Stokes radius can exist in the non-aqueous electrolyte Suppresses the increase in viscosity at low temperatures, so the low-temperature characteristics of non-aqueous lithium electricity storage devices are improved. When the non-aqueous electrolyte contains alkaline earth metal ions other than the above-mentioned alkali metal ions, beryllium ions, magnesium ions, calcium ions, strontium ions, and barium ions are divalent cations, which can increase the capacity of the non-aqueous lithium electricity storage device.

The method of containing the above two or more alkali metal salts in the non-aqueous electrolyte, or the method of containing the alkali metal salt and the alkaline earth metal salt in the non-aqueous electrolyte is not particularly limited, and the two can be dissolved in the non-aqueous electrolyte in advance More than one kind of alkali metal salt made of alkali metal ions can also dissolve alkali metal salts and alkaline earth metal salts. In addition, for example, the following methods can be exemplified: the positive electrode precursor contains one or more of the following formulas where M is one or more selected from Na, K, Rb, and Cs, carbonates such as M ₂ CO ₃ , Oxides such as M ₂ O, hydroxides such as MOH, halides such as MF and MCl, carboxylates such as RCOOM (where R is H, alkyl, or aryl), and/or selected from BeCO ₃ , MgCO ₃ , CaCO ₃ , SrCO ₃ , or BaCO ₃ alkaline earth metal carbonates, and alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth metal halides, and alkaline earth metal carboxylates, and the Method of decomposition in the doping step.

The electrolyte salt concentration of the electrolyte is preferably in the range of 0.5 to 2.0 mol/L. At an electrolyte salt concentration of 0.5 mol/L or more, anions are sufficiently present, and the capacity of the non-aqueous lithium storage element is maintained. On the other hand, at an electrolyte salt concentration of 2.0 mol/L or less, the salt is sufficiently dissolved in the electrolyte, and the electrolyte maintains an appropriate viscosity and conductivity.

When the non-aqueous electrolyte contains two or more alkali metal salts, or contains alkali metal salts In the case of alkaline earth metal salts, the total value of these salt concentrations is preferably 0.5 mol/L or more, and more preferably 0.5 to 2.0 mol/L.

<divider>

The positive electrode precursor and the negative electrode are layered or layered and wound through a separator to form an electrode layered body or an electrode wound body having a positive electrode precursor, a separator and a negative electrode.

As the separator, a separator used for lithium ion secondary batteries, electric double layer capacitors, lithium ion capacitors, etc. can be suitably used.

[Shrinkage of divider (L1-L2)/L1]

In this embodiment, the following separator is used: When the original separator length is set to L1, and the separator length after holding at 120°C for 1 hour is set to L2, according to (L1-L2)/L1 The calculated shrinkage ratio is 0.1 or less, and a non-aqueous lithium electricity storage device having high capacity, excellent output characteristics, and excellent high-temperature storage durability and safety can be obtained.

If the shrinkage ratio (L1-L2)/L1 of the separator is 0.1 or less, the shrinkage of the separator at high temperature is suppressed, and it becomes less likely that the pore diameter and porosity of the separator at high temperature will decrease. Furthermore, since the conduction (short circuit) between the positive and negative electrodes due to the shrinkage of the separator becomes less likely to occur, even if the non-aqueous lithium power storage element is maintained at a high temperature (for example, 85° C. or higher) for a long time, high output performance can be maintained.

The shrinkage ratio (L1-L2)/L1 of the separator is preferably 0.08 or less, more preferably 0.06 or less, and even more preferably 0.04 or less.

The shrinkage of the separator can be measured by the method shown in the examples described later.

[Air permeability of separator P]

In order to improve the low-resistance and high-load charge-discharge cycle characteristics of the non-aqueous lithium storage element, the separator used in this embodiment is preferably a non-aqueous electrolyte with high liquid retention. In addition, for These physical properties are also exhibited under high temperature conditions (for example, 85°C or higher), and it is preferable that even after holding at 120°C for 1 hour, clogging of the separator does not occur, and the liquid retention is maintained.

In order to ensure such characteristics, the air permeability P of the separator after being kept in an environment of 120° C. for 1 hour is preferably 5 seconds/100 mL or more and 300 seconds/100 mL or less. If the air permeability P is 5 seconds/100 mL or more, the strength as a separator can be improved, the insulation between the positive and negative electrodes can be sufficiently ensured, and the internal short circuit of the power storage element can be prevented, which is preferable. If the air permeability P is 300 seconds/100mL or less, sufficient electrolyte can be stored in the separator and the boundary area between the positive electrode and the separator, which reduces the internal resistance of the storage element and improves the cycle of high-load charge and discharge. good.

The air permeability P of the separator is more preferably 7 seconds/100 mL or more and 250 seconds/100 mL or less, still more preferably 15 seconds/100 mL or more and 200 seconds/100 mL or less, and particularly preferably 50 seconds/100 mL or more and 150 seconds/100 mL or less.

This air permeability P can be measured by the method shown in the examples described later.

[Withstand voltage of separator]

In the non-aqueous lithium electricity storage device of this embodiment, a high voltage is applied between the positive electrode and the negative electrode when the negative electrode is doped with lithium. Therefore, the separator of the present embodiment preferably has high insulation so that there is no short circuit between the positive and negative electrodes. In order to guarantee high insulation, it is preferable that the withstand voltage of the separator is 0.4 kV or more. If the withstand voltage is 0.4 kV or more, the short circuit between the positive electrode and the negative electrode when lithium is doped is prevented, and the high capacity and low resistance of the non-aqueous lithium power storage device after completion are maintained, which is preferable.

The withstand voltage of the separator is preferably 0.4 kV or more, more preferably 0.80 kV or more, still more preferably 0.9 kV or more, and may also be 1.0 kV or more, 1.5 kV or more, or 2.0 kV or more. However, the voltage resistance of the separator does not need to be excessively improved. From the viewpoint of the practicality of the non-aqueous lithium electricity storage element, 10.0 kV or less is sufficient, and may also be 8.0 kV or less, 6.0 kV or less, or 4.0 kV or less.

If the withstand voltage is 0.8 kV or more, after the non-aqueous lithium storage element is completed, even if it is charged to a high voltage of 4.1 V or more, for example, a slight short circuit between the positive and negative electrodes of the separator will not occur, which is better.

The withstand voltage of the separator can be measured by the method shown in the examples described later.

[Construction materials of separators]

The separator of the present embodiment preferably includes at least one separator selected from the group consisting of polyolefin, cellulose, and polyamide resin.

One of the embodiments of this embodiment preferably includes a separator containing a coating of polyaramide resin or inorganic fine particles. The separator containing these materials, even when kept at a high temperature (for example, above 85°C), is not likely to shrink, can maintain the liquid retention of the non-aqueous electrolyte, and can maintain the low resistance of the non-aqueous lithium electricity storage element, so it is more good.

Examples of preferred separators of the present embodiment include separators containing a microporous membrane made of polyolefin, separators with a layered body having a coating layer, and the aforementioned coating is made of a microporous membrane made of polyolefin. At least one side contains inorganic The separator of the microparticles and the laminated body having a coating layer and the aforementioned coating layer is a microporous membrane made of polyolefin. At least one side includes a polyaramide resin, a separator containing cellulose nonwoven paper, and the like.

Examples of polyolefins include polyethylene and polypropylene. The polyaramide resin may be para-system polyaramide resin, meta-system polyaramide resin, etc.

The microporous membrane made of polyolefin, the coating layer containing inorganic fine particles, the coating layer containing polyaramide resin, and the nonwoven paper made of cellulose, respectively, may be a single layer or a multilayer laminate.

The inside of the partition may also contain organic or inorganic fine particles.

[Thickness of divider]

The thickness of the separator is preferably 5 μm or more and 35 μm or less. Since the thickness of the separator is 5 μm or more, the self-discharge caused by the internal micro short circuit tends to become smaller, which is preferable. By setting the thickness of the separator to 35 μm or less, the input/output characteristics of the non-aqueous lithium power storage element tend to be higher, which is preferable. The thickness of the separator is more preferably 10 μm or more and 30 μm or less, and still more preferably 15 μm or more and 25 μm or less.

In addition, in the case where the separator has a coating, the thickness of the separator mentioned above refers to the thickness of the entire separator including the coating.

[Manufacturing method of separator]

In the separator of the present embodiment, as long as the heat shrinkage rate (L1-L2)/L1 is 0.1 or less, the air permeability P after being kept at 120°C for 1 hour is preferably 5 seconds/100 mL or more and 300 seconds/100 mL, Preferably, the withstand voltage is 0.4 kV or more, and the manufacturing method is not limited.

In the following, an example manufacturing method of the separator of the present embodiment will be described by taking the case where the separator is made of a microporous membrane of polyolefin as an example.

From the viewpoint of appropriately controlling the physical balance between the permeability of the separator and the film strength, the method for manufacturing the separator of the present embodiment preferably includes: a polymer (typically polyolefin) and a plasticizer Or, the polymer and plasticizer and filler are melt-kneaded to form; extend; extract plasticizer (and filler if necessary); heat fix.

More specifically, the manufacturing method of the separator of this embodiment includes, for example, the following operations (1) to (4).

(1) Kneading polyolefin, plasticizer, and filler (if necessary) to form a kneaded material (step 1), (2) extruding the kneaded material, forming a laminated single layer or several layers of sheet material, and cooling and solidifying (Step 2), (3) After extracting the plasticizer and/or filler from the obtained sheet, make the sheet more than one axis Direction (step 3), and (4) from the extended sheet, after extracting the plasticizer and/or filler as needed, heat treatment is performed to heat fix (step 4).

(step 1)

The polyolefin used in the kneading of step 1 may be composed of one kind of polyolefin, or may be a copolymer containing several kinds of polyolefins, or a polyolefin composition.

Examples of polyolefins include polyethylene (PE), polypropylene (PP), and poly(4-methyl-1-pentene). These can be used alone or as a mixture of two or more.

The viscosity average molecular weight (Mv) of polyolefin is preferably 50,000 to 3 million, and more preferably 150,000 to 2 million. With a viscosity average molecular weight of 50,000 or more, a separator with a high strength tends to be obtained, which is better; with a viscosity of 3 million or less, there is a tendency to obtain an effect of easy extrusion, which is better.

The melting point of polyolefin is preferably 100 to 165°C, more preferably 110 to 140°C. With a melting point above 100°C, there is a tendency for the function of the separator to be stable in a high-temperature environment, and preferably; with a melting point below 165°C, the occurrence of meltdown or fuse at high temperatures can be obtained ) The tendency of the effect is better. The melting point of polyolefin is the peak temperature of the melting peak in the differential scanning calorimetry (DSC) measurement. The melting point of polyolefin when polyolefin is used as a mixture of several types refers to the peak temperature of the peak with the largest melting peak area in the DSC measurement of the mixture.

For polyolefins, it is preferable to use high-density polyethylene in terms of suppressing pore blockage and allowing heat fixation at a higher temperature.

The ratio of the high-density polyethylene contained in the polyolefin, based on the total mass of the polyolefin, is preferably 5 mass% or more, and more preferably 10 mass% or more. With the ratio of high-density polyethylene The rate is 5 mass% or more, which can further suppress the occlusion of the hole and perform heat fixing at a higher temperature. The ratio of the high-density polyethylene contained in the polyolefin, based on the total mass of the polyolefin, is preferably 99% by mass or less, and more preferably 95% by mass or less. With a high-density polyethylene ratio of 99% by mass or less, the separator can not only have the effect of high-density polyethylene, but also have the effect of other polyolefins in a well-balanced manner.

For polyolefins, from the standpoint of improving the shutdown characteristics of the separator used as a capacitor or improving the safety of the nail penetration test, it is preferable to use the viscosity average molecular weight (Mv) as 100,000 to 300,000 polyethylene.

The ratio of polyethylene of 100,000 to 300,000 contained in the polyolefin, based on the total mass of the polyolefin, is preferably 30% by mass or more, and more preferably 45% by mass or more. With the ratio being 30% by mass or more, further, the shutdown characteristics in the case of being used as the separator of the capacitor can be improved, or the safety of the nail penetration test can be improved. The ratio of polyethylene of 100,000 to 300,000 contained in the polyolefin, based on the total mass of the polyolefin, is preferably 100% by mass or less, and more preferably 95% by mass or less.

From the viewpoint of controlling the meltdown temperature, polyolefin can also be used by adding polypropylene.

The ratio of polypropylene contained in the polyolefin, based on the total mass of the polyolefin, is preferably at least 5 mass%, more preferably at least 8 mass%. This ratio is 5% by mass or more, and is preferable from the viewpoint of improving the film rupture resistance at high temperature. The ratio of polypropylene contained in the polyolefin, based on the total mass of the polyolefin, is preferably 20% by mass or less, and more preferably 18% by mass or less. The ratio is 20% by mass or less. The separator is preferable from the viewpoint of achieving not only the effect of polypropylene but also a well-balanced effect of other polyolefins.

The plasticizer used in the kneading of step 1 can be a manufacturer of microporous membranes made of polyolefin in the past. Plasticizers, such as dioctyl phthalate (DOP), diheptyl phthalate, Phthalate esters such as dibutyl phthalate; organic acid esters other than phthalate esters such as adipate and glycerate; phosphate esters such as trioctyl phosphate; liquid paraffin; solid wax; mineral oil, etc. These can be used alone or in combination of two or more. Among these, when considering the compatibility with polyethylene, a particularly preferred phthalate ester is used.

In the kneading of step 1, polyolefin and plasticizer may be kneaded to form a kneaded material, or polyolefin, plasticizer and filler may be kneaded to form a kneaded material. For the filler used in the latter case, at least one of organic fine particles and inorganic fine particles can be used.

Examples of organic fine particles include modified polystyrene fine particles and modified acrylic resin particles.

Examples of materials constituting the inorganic fine particles include oxide-based ceramics such as aluminum oxide, silicon dioxide (silicon oxide), titanium dioxide, zirconium oxide, magnesium oxide, cerium oxide, yttrium oxide, zinc oxide, and iron oxide; Nitride-based ceramics such as silicon, titanium nitride, and boron nitride; silicon carbide, calcium carbonate, aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin, kaolinite, halloysite, pyrophyllite, montmorillonite Other ceramics such as stone, sericite, mica, magnesium aluminum serpentine, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth, silica sand, etc.; glass fiber, etc.

In the kneading of step 1, the blending ratio of polyolefin, plasticizer, and filler used as required is not particularly limited. The ratio of the polyolefin in the kneading compound is preferably 25 to 50% by mass based on the total mass of the kneading compound in terms of the strength and film-forming properties of the resulting separator. From the viewpoint of obtaining a viscosity suitable for extrusion, the ratio of the plasticizer in the compound is preferably 30 to 60% by mass based on the total mass of the compound. In the case of using fillers, from the viewpoint of improving the uniformity of the pore size of the separator obtained from the viewpoint of improving the uniformity of the pore size of the resulting separator, it is preferably 10% by mass or more based on the total mass of the mixture. In terms of sex, it is preferably 40% by mass or less.

During mixing, phenolic, phosphoric, and sulfuric compounds such as tetra[3-(3,5-bis(tertiary butyl)-4-hydroxyphenyl)propionic acid]neopentyl tetraester can also be mixed as needed. Antioxidants; metal soaps such as calcium stearate and zinc stearate; ultraviolet absorbers; light stabilizers; antistatic agents; anti-fogging agents; and various additives such as color pigments.

The kneading method of kneading in step 1 is not particularly limited, and the kneading method used in the past can be appropriately selected and used. For example, the polyolefin, the plasticizer, and a part of the filler used as needed may be mixed in advance, using a Henschel mixer (Henschel mixer), a V-type blender (V-blender), or Proschel mixing. After mixing with a general mixer such as a proshare mixer, ribbon blender, etc., it is further kneaded with the remaining raw materials, or all raw materials can be kneaded at the same time.

The equipment used for kneading is also not particularly limited. For example, melt kneading equipment such as an extruder or a kneader can be used for kneading.

(Step 2)

The forming of the sheet in step 2 includes: extruding the kneaded material obtained in step 1, for example, through a T-shaped die or the like, extruding the extrudate into contact with a heat conductor to cool and solidify. As a heat conductor, for example, metal, water, air, the plasticizer itself, etc. can be used. For example, by sandwiching the extrudate between a pair of rolls and cooling and solidifying, from the viewpoint of increasing the film strength of the obtained sheet-shaped molded body and the viewpoint of improving the surface smoothness of the sheet-shaped molded body are Better.

(Step 3)

The extension in step 3 includes: extending the sheet (sheet-like shaped body) obtained in step 2 to obtain an extended sheet. The stretching method of the sheet during stretching can be exemplified by: MD uniaxial stretching of the roll stretching machine; TD uniaxial stretching of the tenter; the combination of the roller stretching machine and the tenter, or the combination of the tenter and the tenter Combined sequential biaxial stretching; simultaneous biaxial tenter or inflation molding while biaxial stretching, etc. From the viewpoint of obtaining a more uniform film, the sheet stretching method is preferably biaxial stretching at the same time. From the viewpoint of the uniformity of the thickness of the sheet and the balance of tensile elongation, porosity, and average pore diameter, the total area magnification during stretching is preferably 8 times or more, more preferably 15 times or more, and further More than 30 times better. If the total area magnification is 30 times or more, it becomes easy to obtain a high-strength separator. The elongation temperature is preferably 121°C or higher from the viewpoint of imparting high permeability and high temperature and low shrinkage, and is preferably 135°C or lower from the viewpoint of film strength.

The extraction method that is optionally performed before the extension in step 3 may be exemplified by, for example, a method of immersing the sheet or extension sheet in the extraction solvent, a method of spraying the extraction solvent on the sheet or extension sheet, and the like. The extraction solvent is preferably a poor solvent for polyolefins and a good solvent for plasticizers and fillers, and preferably has a boiling point lower than the melting point of polyolefins. Examples of such extraction solvents include hydrocarbons such as n-hexane and cyclohexane; halogenated hydrocarbons such as methylene chloride, 1,1,1-trichloroethane, and fluorocarbons; and ethanol and isopropanol. Alcohols; ketones such as acetone, 2-butanone; alkaline water, etc. One type of extraction solvent may be used alone, or two or more types may be used in combination.

(Step 4)

The heat treatment method in step 4 may be exemplified by, for example, a heat fixing method that uses a tenter and/or roll stretcher to stretch and/or ease the operation at a specified temperature on the stretched sheet obtained in step 3. Ease of operation, directed to the MD of the film (the direction in which the sheet-like film-forming separator is rolled to the roll, also known as the "long-side direction") and/or TD (the direction perpendicular to the MD direction, also known as "Wide direction" or "short side direction"), the reduction operation under the specified relaxation rate. The relaxation rate refers to the value of the MD size of the film after the relaxation operation divided by the MD size of the film before the operation, or, the value of the TD size after the relaxation operation divided by the TD size of the film before the operation, or, at the same time MD and TD The mitigation situation refers to the value of the MD relaxation rate multiplied by the TD relaxation rate. From the viewpoint of controlling the thermal shrinkage rate or controlling the film resistance, the above specified temperature is preferably 130°C or lower, and more preferably 123°C or lower. From the standpoint of extensibility, the specified temperature is preferably 115°C or higher. From the viewpoint of thermal shrinkage and permeability, in step 4, the extended sheet obtained in step 3 is preferably extended to TD by more than 1.5 times, and more preferably extended to TD by more than 1.8 times. From the viewpoint of safety, the elongation of the TD of the extended sheet is preferably 6.0 times or less, and from the viewpoint of maintaining the balance between film strength and permeability, it is more preferably 4.0 times or less. The specified relaxation rate is preferably 0.9 times or less from the viewpoint of suppressing heat shrinkage, and preferably 0.6 times or more from the viewpoint of preventing wrinkle generation and porosity and permeability. The relaxation operation can be carried out in both directions of MD and TD, or it can be carried out only along either of MD and TD. Even if the relaxation operation is performed only along one of MD and TD, not only can the heat shrinkage rate in that operation direction be reduced, but the heat shrinkage rate in the other direction can also be reduced.

The arbitrary extraction before the heat fixation in step 4 can be performed by the same method as the arbitrary extraction before the extension in step 3.

The manufacturing method of the separator, in addition to the operations in steps 1 to 4 described above, as the operation for obtaining the laminate, may further include: laminating several single-layer bodies. The manufacturing method of the separator may further include: subjecting the separator to surface treatment such as electron beam irradiation, plasma irradiation, surfactant coating, and chemical modification.

The fillers arbitrarily used in the manufacture of the separator of this embodiment can be extracted in whole or in part in any operation of the separator manufacturing method, and can also be left in the final separator. The order, method, and frequency of extraction are not particularly limited.

(Adjustment method of shrinkage rate)

The shrinkage rate of the separator of this embodiment type can be changed, for example, by appropriately changing the polyolefin during extrusion The concentration, the blending ratio of various polyolefins in the polyolefin, the molecular weight of the polyolefin, the stretching magnification in the step 3 and/or the heat fixing in the step 4, the stretching temperature, etc. are adjusted.

[Outer body]

For the exterior body, for example, metal cans, laminated packaging materials, etc. can be used. The metal can is preferably made of aluminum. The laminated packaging material is preferably a film in which a metal foil and a resin film are laminated. An example is a three-layer structure composed of an outer resin film/metal foil/internal resin film. The outer resin film is used to prevent damage to the metal foil due to contact, etc. Resin such as nylon and polyester can be used appropriately. Metal foil is used to prevent the penetration of moisture and gas, and copper, aluminum, stainless steel, etc. can be suitably used. The built-in resin film is used to protect the metal foil from the non-aqueous electrolyte contained inside, and to be melt-sealed when the outer body is heat-sealed. Polyolefin, acid-modified polyolefin, etc. can be suitably used.

"Manufacturing method of non-aqueous lithium storage element"

The non-aqueous lithium electricity storage element of this embodiment can be manufactured by, for example, the following method: the electrode laminate or the electrode winding body is accommodated in the exterior body together with the non-aqueous electrolyte, followed by lithium doping, Aging and exhaust. Hereinafter, an exemplary manufacturing method of the non-aqueous lithium power storage element will be described.

<assembly>

[Electrode laminate or electrode wound body]

In the assembly step, typically, a positive electrode precursor and a negative electrode cut into a leaf shape are laminated through a separator to obtain an electrode laminate, and the positive electrode terminal and the negative electrode terminal are connected to the electrode laminate. Alternatively, the positive electrode precursor and the negative electrode are laminated and wound through a separator to obtain an electrode wound body, and the positive electrode terminal and the negative electrode terminal are connected to the electrode wound body. The shape of the electrode wound body may be cylindrical or flat.

Electrode laminate or electrode wound body, connection to positive and negative terminals The method is not particularly limited, and methods such as resistance welding and ultrasonic welding can be used.

[Accommodated in exterior body]

The dried electrode laminate or electrode wound body is preferably housed in an exterior body typified by a metal can and a laminate package, and sealed with only one opening left. The sealing method of the exterior body is not particularly limited, and in the case of using a laminated packaging material, methods such as heat sealing and impulse seal can be used.

[dry]

The electrode laminate or the electrode wound body accommodated in the exterior body is preferably dried to remove the residual solvent. The drying method is not limited, and it can be dried by vacuum drying or the like. The residual solvent is preferably a unit mass of the positive electrode active material layer or the negative electrode active material layer, which is 1.5% by mass or less. If the residual solvent is 1.5% by mass or less, it is preferable because the self-discharge characteristics or cycle characteristics do not easily deteriorate.

<Liquid injection, impregnation, and sealing>

A non-aqueous electrolyte is injected into the outer layer of the electrode laminate or the electrode wound body after drying. After the liquid injection, it is preferable to fully impregnate the positive electrode precursor, negative electrode, and separator with a non-aqueous electrolyte. In a state where at least a part of the positive electrode precursor, the negative electrode, and the separator is not immersed in the non-aqueous electrolyte, the doping is unevenly performed in the lithium doping described later, so there is resistance of the resulting non-aqueous lithium electricity storage element Increased or reduced durability. The impregnation method is not particularly limited. For example, it can be used: the non-aqueous lithium storage element after injection is placed in a decompression chamber with the external body open, and the chamber is decompressed using a vacuum pump. And how to return to atmospheric pressure again. After impregnation, it is sealed by sealing while decompressing the external body in an open state.

[Alkali metal doping step]

In the alkali metal doping step, it is preferable to apply a voltage between the positive electrode precursor and the negative electrode to divide The alkali metal compound in the positive electrode precursor is decomposed to release alkali metal ions, and the alkali metal ions are reduced at the negative electrode so that the alkali metal ions are pre-doped in the negative electrode active material layer.

In the alkali metal doping step, along with the oxidative decomposition of the alkali metal compound in the positive electrode precursor, gas such as CO _{2 is} generated. Therefore, when voltage is applied, it is preferable to adopt a method of releasing the generated gas to the outside of the exterior body. This method can be exemplified by, for example, a method of applying voltage in a state where a part of the exterior body is open; applying in a state where an appropriate gas release means such as an exhaust valve or a gas-permeable membrane is provided in advance in a part of the exterior body Voltage method; etc.

In the specification of the present invention, when the alkali metal used is lithium, the “alkali metal doping step” is referred to as a “lithium doping step”.

<aging>

After the alkali metal is doped, it is preferable to age the non-aqueous lithium power storage device. During aging, the organic solvent in the non-aqueous electrolyte decomposes on the negative electrode, and a lithium ion-permeable solid polymer film is formed on the surface of the negative electrode.

The method of aging is not particularly limited, for example, it can be used: stored at a temperature of 25°C to 100°C, a voltage of 2.0V to 4.5V, or floated, or a charge and discharge cycle, or a combination of these The method of making the solvent in the electrolyte react.

<exhaust>

After aging, it is preferable to further evacuate the gas, and reliably remove the gas remaining in the non-aqueous electrolyte, the positive electrode, and the negative electrode. In a state where gas remains in at least part of the non-aqueous electrolyte, the positive electrode, and the negative electrode, ion conduction is hindered, so the resistance of the obtained non-aqueous lithium electricity storage element increases.

The method of exhausting is not particularly limited, and it can be used, for example, in the opening of the exterior body In a state where the non-aqueous lithium storage element is installed in the decompression chamber, a vacuum pump is used to reduce the pressure in the chamber.

"Characteristics Evaluation of Non-aqueous Lithium Storage Element"

Hereinafter, the method for evaluating the characteristics of the non-aqueous lithium electricity storage device according to this embodiment will be described.

<take of separator>

The characteristic evaluation of the separator of the non-aqueous lithium electricity storage element of this embodiment mode is performed by taking out the separator from the electricity storage element.

The characteristic evaluation of the separator is preferably carried out after the non-aqueous lithium power storage element of this embodiment is disassembled under anaerobic conditions, washed, and dried. The cleaning of the separator is to remove the electrolyte attached to the surface of the separator.

The washing solvent of the separator is sufficient as long as it can wash the lithium salt electrolyte adhering to the surface of the separator, so carbonate solvents such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate can be suitably used. The washing method is, for example, immersing the separator in a carbonate solvent of 50 to 100 times the mass of the separator for more than 10 minutes, and then changing the solvent to immerse the separator again. Thereafter, the separator is taken out of the carbonate solvent, for example, vacuum drying. The conditions of vacuum drying, for example, can be set to temperature: 0~100℃, pressure: 0~20kPa, and time: 1~40 hours. In vacuum drying, the temperature is preferably set to such an extent that the shape of the partition does not change.

The separator after being taken, washed, and dried can be used as a measurement sample, and the shrinkage rate (L1-L2)/L1, air permeability P, and withstand voltage can be measured by the method described in the examples.

<C rate>

The following C rate of current refers to the current value that will be discharged within 1 hour when the constant current discharge from the upper limit voltage to the lower limit voltage is set to a relative value of 1C. In this manual, the upper limit The voltage Vmax and the lower limit voltage Vmin are individually different according to the embodiment and the comparative example, so they are defined individually in the individual embodiments and the comparative example.

<discharge capacity>

In this specification, the discharge capacity Q refers to the value obtained by the following method.

First, the cell corresponding to the non-aqueous lithium storage element is charged in a constant temperature bath set at 25°C at a constant current of 20C until it reaches Vmax, and then, a constant voltage charge is applied to apply a constant voltage of Vmax 30 minutes in total. Thereafter, a constant current discharge was applied at a current value of 2C until Vmin. Let the discharge capacity at this time be the discharge capacity Q (mAh) of this embodiment.

(Electrostatic capacity)

In this specification, the electrostatic capacity F(F) refers to the value obtained by the following method.

First, the unit corresponding to the non-aqueous lithium electricity storage element was charged in a constant temperature bath set at 25°C at a constant current value of 2C until it reached Vmax, and then a constant voltage charging with a constant voltage applied to Vmax was performed for a total of 30 minutes. After that, a constant current discharge was applied at a current value of 2C until the capacitance at Vmin was set to Q. The electrostatic capacity F(F) refers to the value obtained by using the Q obtained here by the electrostatic capacity F=Q/(Vmax-Vmin).

<Internal resistance at room temperature discharge>

In this specification, the normal temperature discharge internal resistance Ra (Ω) refers to the value obtained by the following method.

First, the unit corresponding to the non-aqueous lithium power storage element was charged in a constant temperature bath set at 25°C at a constant current value of 20C until it reached Vmax, and then a constant voltage charging with a constant voltage of Vmax applied for a total of 30 minutes. Next, the sampling interval was set to 0.05 seconds, and constant current discharge was performed at a current value of 20C until Vmin to obtain a discharge curve (time-voltage). Approximately extrapolate the discharge time obtained from the voltage values at the time of 1 second and 2 seconds in the discharge curve by a straight line = 0 When the voltage in seconds is set to Eo, it is calculated from the falling voltage △E=Vmax-Eo and Ra=△E/(20C (current value A)).

(Electric energy)

In this specification, the electric energy E(Wh) refers to the value obtained by the following method.

It refers to the value calculated from F×(Vmax ² -Vmin ² )/2/3,600 using the electrostatic capacity F(F) calculated by the method described above.

(volume)

The volume V(L) of the electricity storage element refers to the volume of the portion of the exterior body that houses the electrode laminate or the electrode wound body.

For example, in the case of an electrode laminate or an electrode wound body accommodated by a laminated film, typically, in the electrode laminate or the electrode wound body, there are regions where the positive electrode active material layer and the negative electrode active material layer exist and are accommodated In the laminated film formed by the cup. The volume of the storage element (V _x ) is determined by the length of the outer side (l _x ) and the width of the outer side (w _x ) of the cup-shaped portion, and the thickness (t _x ) of the storage element containing the laminated film, with V _x = l _x ×w _x ×t _{x is} calculated.

In the case of an electrode laminate or an electrode wound body accommodated in a square-shaped metal can, the volume of the electricity storage element is simply the volume of the outer size of the metal can. That is, the volume (V _y ) of this storage element is determined by the outer length (l _y ), the outer width (w _y ), and the outer thickness (t _y ) of the rectangular metal can, with V _y =l _y × w _y ×t _{y is} calculated.

In the case of the electrode wound body accommodated in a cylindrical metal can, the volume of the electric storage element also uses the volume of the outer size of the metal can. That is, the volume (V _z ) of this storage element is based on the outer radius (r) and the outer length (l _z ) of the bottom or upper surface of the cylindrical metal can, with V _z =3.14×r×r× l _{z is} calculated.

<High Temperature Storage Test 1>

In the specification of this case, the rate of increase in the internal resistance of the room temperature discharge after the high-temperature storage test 1 was measured according to the following method.

First, the unit corresponding to the non-aqueous lithium power storage element was set in a thermostat set at 25° C., and the internal resistance Ra at room temperature at Vmax=3.8V and Vmin=2.2V was measured. After that, the cell was charged with a constant current at a current value of 100C until an arbitrary voltage of 4.0V, followed by a constant voltage charging with a constant voltage of 4.0V applied for 10 minutes. After that, the unit was stored in an environment of 85°C, and it was taken out from the environment of 85°C every two weeks, and charged to the cell voltage of 4.0 V by the aforementioned charging operation, and the unit was again stored in an environment of 85°C. By repeating this operation at a specified time, a high-temperature storage test is performed.

For the unit after the high temperature storage test, using the resistance value obtained by the same measurement method as the internal resistance of the normal temperature discharge and the internal resistance of the normal temperature discharge after the high temperature storage test as Rb, calculate the start of the high temperature storage test based on Rb/Ra Rate of increase in internal resistance after the high-temperature storage test 1 of the internal resistance Ra before normal temperature discharge.

In the non-aqueous lithium power storage element of this embodiment, the internal resistance of the initial normal temperature discharge is set to Ra (Ω), and the internal resistance of the normal temperature discharge after storage for 1,000 hours at a cell voltage of 4.0 V and an ambient temperature of 85° C. is set to Rb( Ω), the internal resistance increase rate represented by the ratio Rb/Ra of the two can be 3.0 or less.

Rb/Ra is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 from the viewpoint of showing sufficient charge capacity and discharge capacity for a large current when exposed to a high temperature environment for a long time the following. If Rb/Ra is equal to or less than the above upper limit, long-term stable and excellent output characteristics can be obtained, which leads to a longer life of the device.

In the non-aqueous lithium electricity storage device of this embodiment, the internal resistance increase rate Rb/Ra may be 3.0 or less Further, it may be 2.5 or less, in particular, 2.0 or less, 1.5 or less, 1.4 or less, 1.3 or less, or 1.12 or less.

<High Temperature Storage Test 2>

In this specification, the resistance change rate after the high-temperature storage test 2 is measured according to the following method.

First, the unit corresponding to the non-aqueous lithium power storage element was set in a thermostat set at 25° C., and the internal resistance Ra at room temperature at Vmax=3.8V and Vmin=2.2V was measured. Thereafter, the cell was charged with a constant current at a current value of 20C until 4.0V, followed by constant voltage charging with a constant voltage of 4.0V applied for a total of 30 minutes. Next, the internal resistance Rb after storage for 2 months in a thermostat set at 85° C. was measured by the same method as the internal resistance Ra. Then, let Rb/Ra be the resistance change rate after the high-temperature storage test. The non-aqueous lithium electricity storage device of the present embodiment preferably satisfies the following (c): (c) Rb/Ra is 3.0 or less.

The resistance change rate Rb/Ra after the high-temperature storage test 2 is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.0 or less. If the resistance increase rate after the high-temperature storage test is 3.0 or less, long-term stable and excellent input-output characteristics can be obtained, resulting in a longer life of the non-aqueous lithium power storage device. The lower limit of Rb/Ra is preferably 0.9 or more.

<High Temperature Storage Test 3>

In this specification, the resistance change rate after the high-temperature storage test 3 is measured according to the following method.

(Resistance change rate after high temperature storage)

First, place the unit corresponding to the non-aqueous lithium storage element in a thermostat set at 25°C and measure The internal resistance Ra at room temperature when Vmax=4.0V and Vmin=2.2V is determined. Thereafter, the cell was charged with a constant current at a current value of 20C until 4.0V, followed by constant voltage charging with a constant voltage of 4.0V applied for a total of 30 minutes. Next, the internal resistance Rb after storing the unit in a thermostat set at 100° C. for 2 weeks was measured. Let Rb/Ra be the resistance change rate after the high-temperature storage test.

The resistance change rate Rb/Ra after the high-temperature storage test 3 is preferably 2.0 or less, more preferably 1.7 or less, and still more preferably 1.5 or less. If the resistance increase rate after the high-temperature storage test is 2.0 or less, the characteristics under a high-temperature environment of 85°C or more are maintained. Therefore, long-term stable and excellent input-output characteristics can be obtained, which leads to a longer life of the non-aqueous lithium power storage element. The lower limit of Rb/Ra is preferably 0.9 or more.

<High Temperature Storage Test 4>

In this specification, the resistance change rate after the high-temperature storage test 4 is measured according to the following method.

(Resistance change rate after high temperature storage)

First, the unit corresponding to the non-aqueous lithium electricity storage element was set in a thermostat set at 25° C., and the internal resistance Ra at room temperature when Vmax=4.1V and Vmin=2.2V was measured. Thereafter, the unit was charged with a constant current at a current value of 20C until 4.1V, followed by constant voltage charging with a constant voltage of 4.1V applied for a total of 30 minutes. Next, the internal resistance Rb after storing the unit in a thermostat set at 85°C for 1000 hours was measured. Let Rb/Ra be the resistance change rate after the high-temperature storage test.

The resistance change rate Rb/Ra after the high-temperature storage test 4 is preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less. If the resistance increase rate after the high-temperature storage test is 3.0 or less, the characteristics under a high-temperature environment of 85°C or more are maintained. Therefore, long-term stable and excellent input-output characteristics can be obtained, which leads to a longer life of the non-aqueous lithium power storage element. The lower limit of Rb/Ra is preferably 0.9 or more.

<Low-temperature discharge internal resistance Rd>

In this specification, the low-temperature discharge internal resistance Rd refers to the value obtained by the following method.

The low-temperature discharge internal resistance Rd was measured with Vmax=3.8V and Vmin=2.2V. First, the unit corresponding to the non-aqueous lithium electricity storage element was placed in a thermostat set at -30°C for 2 hours. With the constant temperature bath maintained at -30°C, constant current charging was carried out at a current value of 1.0C until 3.8V, followed by constant voltage charging with a constant voltage of 3.8V applied for a total of 2 hours. Next, a constant current discharge was carried out at a current value of 10C until 2.2V, and a discharge curve (time-voltage) was obtained. In this discharge curve, the voltage value at the time point of the discharge time of 2 seconds and 4 seconds is approximated by a straight line. When the voltage of the discharge time = 0 seconds is set to Eo, according to the drop voltage △E=3.8-Eo, And Rd=△E/(10C (current value A)) calculated value.

The low-temperature discharge internal resistance is divided by the value of the normal-temperature discharge internal resistance Ra/Ra when Vmax=3.8V and Vmin=2.2V, preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less. If Rd/Ra is 3.0 or less, a sufficient discharge capacity can be obtained even at a low temperature of -30°C. Therefore, for example, in an electric vehicle, even at a low temperature of -30°C, it can be used in peak assist applications such as starters.

(Condition a~c)

The non-aqueous lithium storage element of this embodiment type preferably satisfies the following conditions (a) and (b): (a) the product Ra of Ra and F. F is 0.3 or more and 3.0 or less; and (b) E/V is 15 or more and 80 or less.

Regarding condition (a), Ra. F is the product of the initial internal resistance Ra and the electrostatic capacity F at 3.8V. From the viewpoint of showing sufficient charging capacity and discharging capacity for a large current, it is preferably 3.0 or less, more preferably 2.5 or less, and still more Best line below 2.0. If Ra. When F is 3.0 or less, a power storage element having excellent input and output characteristics can be obtained. Therefore, by using a combination of The electric system and, for example, a high-efficiency engine can sufficiently withstand the high load applied to the power storage element, which is preferable. Ra. F is preferably 0.3 or more, 0.4 or more, or 0.5 or more from the viewpoint of maintaining the characteristics of the electricity storage device.

Regarding condition (b), E/V is the ratio of electric energy E to volume V, and from the viewpoint of showing sufficient charge capacity and discharge capacity, it is preferably 15 or more, more preferably 18 or more, and still more preferably Department above 20. If the E/V is 15 or more, a power storage element having excellent volume energy density can be obtained. Therefore, when a power storage system using a power storage element is used in combination with, for example, an engine of a car, it becomes possible to install the power storage system in a confined narrow space in the car, which is preferable. E/V is preferably 80 or less, 70 or less, or 60 or less from the viewpoint of maintaining the characteristics of the power storage device.

The non-aqueous lithium electricity storage element of this embodiment is preferably stored in the high temperature storage test 2 to satisfy the following condition (c): (c) Rb/Ra is 3.0 or less. The resistance change rate Rb/Ra is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. If Rb/Ra is 3.0 or less, long-term stable and excellent input-output characteristics can be obtained, resulting in a longer life of the non-aqueous lithium power storage device. The lower limit of Rb/Ra is preferably 0.9 or more.

[3.5V micro short circuit check test]

In this specification, the micro-short circuit of the non-aqueous lithium electricity storage element is determined by the following method.

First, the electrode body was discharged with a constant current at a current value of 100mA until 2.5V, and then charged at a constant current with a current value of 100mA until a voltage of 3.5V, and then continued to charge at a constant voltage of 3.5V for 2 hours to adjust the voltage To 3.5V. Next, the electrode body is allowed to stand for 1 week in a thermostat set at 25°C under a pressure of 10 kPa, and it is judged that the voltage drops below 3.0V It is a short circuit.

[4.1V micro short circuit check test]

In this specification, the micro-short circuit of the non-aqueous lithium electricity storage element under the 4.1V charge state is determined by the following method.

First, the electrode body is discharged with a constant current at a current value of 100mA until 3.5V, and then charged at a constant current with a current value of 100mA until a voltage of 4.1V, and then continuously charging at a constant voltage of 4.1V for 2 hours to adjust the voltage To 4.1V. Next, the electrode body was allowed to stand for 24 hours under a pressure of 10 kPa in a thermostat set at 25°C, and it was judged that the voltage decreased to 3.9 V or less as a micro-short circuit.

<Quantification of carbon materials, lithium transition metal oxides, alkali metal compounds in the positive electrode active material layer>

The positive electrode active material layer contained in a mass ratio of carbon material A _1, quantitative method for the mass ratio of the lithium transition metal oxide of the A _2, and the mass ratio of the alkali metal compound of A ₃ is not particularly limited, for example, by the following Method.

Determination of the area of the precursor of the positive electrode is not particularly limited, but in view reduce the deviation measured in terms of ² or more preferably ² or less based 5cm 200cm, more preferably ² or more ^{and 2} or less based 25cm 150cm. If the area is 5 cm ² or more, the reproducibility of the measurement can be ensured. If the area is 200 cm ² or less, the operability of the sample is excellent.

First, the positive electrode precursor was cut into the above-mentioned area, and vacuum dried. The conditions for vacuum drying are preferably, for example, temperature: 100 to 200°C, pressure: 0 to 10 kPa, time: 5 to 20 hours, and the amount of residual moisture in the positive electrode precursor becomes 1% by mass or less. The residual amount of water can be quantified by the Karl-Fisher method.

The positive electrode precursor obtained after vacuum drying was weighed (M ₀ ). Next, it is immersed in distilled water of 100 to 150 times the weight of the positive electrode precursor for more than 3 days to dissolve the alkali metal compound into the water. During the immersion, it is preferable to close the lid of the container so that the distilled water does not volatilize. After immersion for 3 days or more, the positive electrode precursor was taken out from distilled water and vacuum dried in the same manner as above. The weight (M ₁ ) of the obtained positive electrode precursor was measured. Next, the positive electrode active material layer coated on one side or both sides of the positive electrode current collector is removed using a spatula, brush, bristles, or the like. The weight (M ₂ ) of the remaining positive electrode current collector was measured, and the mass ratio A _{3 of the} alkali metal compound was calculated using the following formula (1).

A ₃ =(M ₀ -M ₁ )/(M ₀ -M ₂ )×100 (1)

Next, in order to calculate A ₁ and A ₂ , the TG curve was measured on the positive electrode active material layer obtained by removing the alkali metal compound under the following conditions.

. Sample tray: platinum

. Gas: Atmospheric environment, or compressed air

. Heating rate: below 0.5℃/min

. Temperature range: 25℃~500℃ above the melting point of lithium transition metal oxide minus 50℃

The mass of 25° C. of the obtained TG curve is set to M ₃ , and the mass of the initial temperature at which the mass reduction rate at a temperature of 500° C. or more is M ₃ ×0.01/min or less is set to M ₄ .

The carbon material is completely oxidized and burned by heating at a temperature below 500°C in an oxygen-containing environment (for example, atmospheric environment). On the other hand, even in an oxygen-containing environment, the lithium transition metal oxide will not lose mass until the melting point of the lithium transition metal oxide is reduced by a temperature of 50°C.

Therefore, the content A ₂ of the lithium transition metal oxide of the positive electrode active material layer can be calculated by the following formula (2). When the positive electrode active material layer does not contain the lithium transition metal oxide, M ₄ is 0, so Calculate A ₂ as 0.

A ₂ =(M ₄ /M ₃ )×{1-(M ₀ -M ₁ )/(M ₀ -M ₂ )}×100 (2)

In addition, the content A ₁ of the carbon material of the positive electrode active material layer can be calculated by the following formula (3).

A ₁ ={(M ₃ -M ₄ )/M ₃ }×{1-(M ₀ -M ₁ )/(M ₀ -M ₂ )}×100 (3)

In addition, in the case where a plurality of alkali metal compounds are included in the positive electrode active material layer; in addition to the alkali metal compounds, M ₂ O and the like in which M is one or more selected from Na, K, Rb, and Cs are included in the following formula Oxides, hydroxides such as MOH, halides such as MF and MCl, oxalates such as M ₂ (CO ₂ ) ₂ , carboxylates such as RCOOM (where R is H, alkyl, or aryl) In the case of an acid salt; and the positive electrode active material layer, including alkaline earth metal carbonate selected from BeCO ₃ , MgCO ₃ , CaCO ₃ , SrCO ₃ , and BaCO ₃ , or alkaline earth metal oxide, alkaline earth metal hydroxide, alkaline earth metal halide Substances, alkaline earth metal oxalate, or alkaline earth metal carboxylate, the total amount of these is calculated as the amount of alkali metal compound.

When a conductive material, a binder, a thickener, etc. are included in the positive electrode active material layer, the total amount of carbon materials and these materials is calculated as A ₁ .

<Identification method of alkali metal in electrode>

The identification method of the alkali metal compound contained in the positive electrode is not particularly limited, and for example, it can be identified by the following method. The identification of the alkali metal compound is preferably performed by combining a plurality of analysis methods described below.

When the analysis method cannot be used to identify the alkali metal compound, ⁷ Li-solid-state NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), AES (European Electronic Energy Spectroscopy), TPD/MS (Programmed Temperature Controlled Desorption Mass Spectrometry), DSC (Differential Scanning Calorimetry), etc., to identify alkali metal compounds.

[Microscopic Raman spectroscopy]

The alkali metal carbonate and the positive electrode active material can be judged by Raman imaging of the carbonate ion on the surface of the positive electrode precursor measured at an observation magnification of 1000 times to 4000 times. As an example of measurement conditions, the excitation light is set to 532 nm, the excitation light intensity is set to 1%, the length of the objective lens is set to 50 times, the diffraction grating is set to 1800 gr/mm, and the mapping method is set to point scanning. (Slit 65 mm, pixel combination 5 pix), step 1 mm, exposure time per point set to 3 seconds, cumulative count set to 1, and measurement with a clutter filter. For the measured Raman spectrum, set a straight line baseline in the range of 1071~1104cm ^-1 , calculate the area as the peak of carbonate ion by the positive value compared with the baseline, and accumulate the frequency, then deduct from the frequency distribution of carbonate ion The frequency of the carbonate ion peak area relative to the noise component approximated by the Gaussian function.

[X-ray photoelectron spectroscopy (XPS)]

The bonding state of alkali metal compounds can be determined by XPS analysis of the electronic state. As an example of measurement conditions, the monochromatic AlKα is used as the X-ray source, the diameter of the X-ray beam is 100 μm φ (25 W, 15 kV), and the pass energy is as detailed scan: 58.70 eV, neutralized with charge, The scan number is set to detailed scan: 10 times (carbon, oxygen) 20 times (fluorine) 30 times (phosphorus) 40 times (lithium element) 50 times (silicon), the energy level is set to detailed scan: 0.25eV . Preferably, the surface of the positive electrode is cleaned by sputtering before XPS measurement. For sputtering conditions, for example, the surface of the positive electrode can be cleaned under the conditions of an acceleration voltage of 1.0 kV and a range of 2 mm×2 mm for 1 minute (1.25 nm/min in terms of SiO ₂ conversion).

For the obtained XPS spectrum, the peak of Li1s with a binding energy of 50~54eV can be assigned to LiO ₂ or Li-C bonding; the peak of 55~60eV can be assigned to LiF, Li ₂ CO ₃ , Li _x PO _y F _z ( In the formula, x, y, and z are integers from 1 to 6); the C1s binding energy peak of 285eV is assigned to CC bonding, the 286eV peak is assigned to CO bonding, and the 288eV peak is assigned to COO, 290 The peak of ~292eV is attributed to CO ₃ ^2- and CF bonding; the peak of the binding energy of O1s 527~530eV is attributed to O ^2- (Li ₂ O), the peak of 531~532eV is attributed to CO, CO ₃ , OH, PO _x (where x is an integer from 1 to 4), SiO _x (where x is an integer from 1 to 4), the peak of 533eV belongs to CO, SiO _x (where x is an integer from 1 to 4) ); the peak of the binding energy of 685eV of F1s is assigned to LiF, the peak of 687eV is assigned to CF bonding, Li _x PO _y F _z (where x, y, and z are integers from 1 to 6 respectively), PF ₆ ^-; of P2p the binding energy, the peak attributed 133eV sum of PO _x (wherein, x is an integer from 1 to 4 of), peak attributed 134 ~ 136eV sum of PF _x (wherein, x is an integer from 1 to 6 of ); The peak of the binding energy of 99eV of Si2p is assigned to Si, silicide, and the peak of 101~107eV is assigned to Si _x O _y (where x and y are arbitrary integers).

For the obtained spectrum, when the peaks coincide, it is better to assume Gaussian function or Lorentzian function to perform peak separation and then assign the spectrum. From the measurement result of the obtained electronic state and the result of the element ratio, the presence of the alkali metal compound can be identified.

[Ion chromatography]

By washing the positive electrode precursor with distilled water and analyzing the washed water by ion chromatography, the carbonate ion dissolved into the water can be identified. The column used can be ion exchange type, ion exclusion type, and reverse phase ion pair type. Detector, can use conductivity detector, ultraviolet and visible light absorbance detector, electrochemical detector, etc., can be used to set the suppressor in front of the detector suppressor way, or without the suppressor to conduct electricity The solution with a lower degree is used as a suppressor-free method for the eluate. In addition, a mass spectrometer or a charged particle detector can also be used as a detector combination for measurement.

The retention time of the sample, as long as the conditions of the column and eluent used have been determined, each The retention time of the ion species composition is constant. In addition, although the magnitude of the induction of the peak of each ion species is different, it is proportional to the concentration of the ion species. The qualitative and quantitative determination of the ionic species composition can be performed by measuring the standard solution of known concentration that has ensured traceability in advance.

<Quantitative method of alkali metal elements ICP-MS>

For the measurement sample, strong acid such as concentrated nitric acid, concentrated hydrochloric acid, aqua regia, etc. are used for acid decomposition, and the resulting solution is diluted with pure water so that the acid concentration is 2% to 3%. Regarding acid decomposition, the sample may be appropriately heated and pressurized. The dilution obtained by ICP-MS analysis is preferably pre-added with a known amount of element as an internal standard at this time. When the alkali metal element to be measured is at or above the upper limit of the measurement concentration, it is preferably further diluted while maintaining the acid concentration of the dilution liquid. For the obtained measurement results, each element can be quantified based on the calibration curve prepared in advance using the standard solution for chemical analysis.

<BET specific surface area and average pore size, mesopore volume, micropore volume>

In the specification of this case, the BET specific surface area, average pore diameter, mesopore volume, and micropore volume are the values obtained by the following methods, respectively. The sample was vacuum-dried at 200° C. for one day and night, and nitrogen was used as the adsorbate for the measurement of adsorption and desorption isotherms. Using the isotherm on the adsorption side obtained here, the BET specific surface area is determined by the BET multi-point method or the BET 1-point method, and the average pore diameter is calculated by dividing the total pore volume per unit mass by the BET specific surface area and the mesopore volume. The BJH method and the micropore volume are calculated separately by the MP method.

The BJH method is a calculation method generally used for the analysis of mesopores, and it is advocated by Barrett, Joyner, Halenda, etc. (EPBarrett, LGJoyner and P. Halenda, J. Am. Chem.soc., 73,373 (1951)) (Non-Patent Document 1).

MP method refers to the use of "t-drawing method" (B.C. Lippens, J.H.de Boer, J. Catalysis, 4319 (1965) (Non-Patent Document 2)), the method for obtaining the pore volume, pore area, and pore distribution is a method conceived by M. Mikhail, Brunauer, Bodor (RSMikhail , s. Brunauer, EEBodor, J. Colloid Interface Sci., 26, 45 (1968) (Non-Patent Document 3)).

<average particle size>

In the specification of this case, the average particle size refers to the particle size at the point of 50% of the cumulative curve when the cumulative volume is obtained by setting the entire volume to 100% when measuring the particle size distribution using a particle size distribution measuring device (that is, 50% diameter (Median diameter)). This average particle size can be measured using a commercially available laser diffraction particle size distribution measuring device.

In the specification of this case, the primary particle size can be obtained by the following methods: taking a digital field of view of the powder with an electron microscope, measuring the particle size of the particles in these fields of view using a fully automatic image processing device, etc. 2,000 to 3,000 The arithmetic average of these is set to the primary particle size.

<dispersion>

In this specification, the degree of dispersion is a value obtained by performing a dispersion degree evaluation test with a particle size meter specified in JIS K5600. That is, for a particle size meter having a groove of a desired depth corresponding to the particle size, a sufficient amount of sample is flowed into the deeper bottom end of the groove and allowed to slightly overflow the groove. The long side of the scraper is parallel to the width direction of the particle size meter, and the blade of the scraper is placed in contact with the deeper bottom end of the groove of the particle size meter, and the scraper is held flat against the surface of the particle size meter and kept The long-side direction is at a right angle, at an equal speed, and the surface of the particle size meter is scraped to the depth of the groove 0 in 1 to 2 seconds. After the scraping, the light is observed at an angle of more than 20° and less than 30° within 3 seconds, and read Take the depth at which the particles appear in the groove of the particle size meter.

<viscosity and TI value>

In the specification of this case, the viscosity (ηb) and the TI value are the values obtained according to the following methods. First, a stable viscosity (ηa) was obtained by measuring with an E-type viscometer under conditions of a temperature of 25° C. and a shear rate of 2 s ⁻¹ for 2 minutes or more. The viscosity (ηb) was obtained by changing the shear rate to 20s ^-1 and measuring it under the same conditions as above. Using the viscosity value obtained above, the TI value is calculated according to the formula of TI value=ηa/ηb. When the shear speed is increased from 2s ^-1 to 20s ^-1 , the shear speed can be increased in one step, or the shear speed can be increased in multiple steps within the above range, while appropriately obtaining the shear speed The viscosity increases the shear rate.

<Measurement of cyclic voltammogram of non-aqueous electrolyte>

The method for measuring the cyclic voltammogram of the non-aqueous electrolyte contained in the non-aqueous lithium electricity storage element in this embodiment is described below.

First, the non-aqueous lithium electricity storage element is disassembled and the non-aqueous electrolyte is taken out. For the removed non-aqueous electrolyte, aluminum foil was used as a working electrode, and lithium metal was used as a counter electrode and a reference electrode, respectively, to fabricate a triode cell. In this case, the configuration of the triode unit may be, for example, a layer sandwiched between a working electrode and a counter electrode, and the reference electrode may be in contact with the layered body fluid and be stored in a layered film side by side, or may be a bottle The container is filled with non-aqueous electrolyte, and the shape of the working electrode, counter electrode and reference electrode is immersed. When a small amount of non-aqueous electrolyte is used, it is preferable to use the above-mentioned laminated shape. The aluminum foil used as a working electrode is not particularly limited. From the viewpoint of ease of handling, the thickness is preferably 10 to 100 μm, and the area is preferably 1 to 100 cm ² .

The above-mentioned three-pole unit was scanned from 3V to 5V at a speed of 5mV/sec in a thermostat set at 25°C, and then from 5V to 3V at a speed of 5mV/sec. Using this as one cycle, a total of 5 cycles were performed to measure the current response. In this specification, using the current reaction result of the fifth cycle, the maximum reaction current value in the voltage range of 3.8 V (vs. Li/Li ⁺ ) or more and 4.8 V (vs. Li/Li ⁺ ) or less is calculated and used for evaluation. The value per unit area of the aluminum foil of the working electrode.

<Use of non-aqueous lithium storage element>

The power storage module can be manufactured by connecting a plurality of non-aqueous lithium power storage elements of this embodiment in series or parallel. In addition, the non-aqueous lithium power storage element and power storage module of the present embodiment can achieve both high input and output characteristics and high temperature safety, so it can be used in power regeneration auxiliary systems, power load leveling systems, and continuous power supplies System, non-contact power supply system, energy harvesting system, power storage system, electric steering system, emergency power supply system, in-wheel motor system, idle flameout system, rapid charging system, smart grid system, etc.

The power storage system is suitably used for natural power generation such as solar power generation or wind power generation, the power load leveling system is suitably used for microgrids, etc., and the uninterruptible power supply system is suitably used for factory production equipment, etc. In non-contact power supply systems, non-aqueous lithium storage elements are used appropriately for leveling of voltage fluctuations such as microwave transmission or electric field resonance and energy storage. In energy harvesting systems, non-aqueous lithium storage elements are In order to use the electric power generated by vibration power generation etc., it is suitably utilized.

In a power storage system, a battery stack is connected to a plurality of non-aqueous lithium power storage elements in series or parallel, or is connected to non-aqueous lithium power storage elements in series or parallel, and a lead battery, a nickel-metal hydride battery, a lithium ion secondary battery, or a fuel cell.

In addition, the non-aqueous lithium power storage element of this embodiment type can realize both high input and output characteristics and safety at high temperatures, so it can be installed in, for example, electric vehicles, plug-in hybrid vehicles, hybrid vehicles, electric vehicles, etc. Transportation. The above-described electric power regeneration assist system, electric power steering system, emergency power supply system, in-wheel motor system, idling flameout system, or a combination of these are suitably mounted on the vehicle.

【Example】

The embodiments of the present invention will be specifically described below with examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

<Crushing of lithium carbonate>

Lithium carbonate is crushed by brittle fracture while preventing thermal denaturation at a temperature of -196°C.

200g of lithium carbonate with an average particle size of 53 μm was used, and a pulverizer (liquid nitrogen bead mill LNM) manufactured by AIMEX was used. After cooling to -196°C with liquid nitrogen, dry ice beads were used to pulverize at a peripheral speed of 10.0 m/s for 9 minutes. . The average particle size of the obtained lithium carbonate was 2.26 μm.

<Preparation of positive active material>

[Modulation of activated carbon 1]

The crushed coconut shell carbides were carbonized in a small carbonization furnace under a nitrogen atmosphere at 500°C for 3 hours to obtain carbides. The resulting carbide was placed in an activation furnace, and 1 kg/h of steam heated by a preheating furnace was introduced into the activation furnace, and the temperature was raised to 900°C for 8 hours to activate. Take out the activated carbide and cool it under nitrogen environment. The obtained activated carbon was washed with running water for 10 hours and then dehydrated. Activated carbon 1 is obtained by drying the washed and dehydrated activated carbon in an electric dryer maintained at 115°C for 10 hours and then pulverized with a ball mill for 1 hour.

For this activated carbon 1, the average particle diameter was measured using a laser diffraction particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation, and the result was 4.2 μm. Further, for activated carbon 1, the pore distribution was measured using a pore distribution measuring device (AUTOSO RB-1AS-1-MP) manufactured by YUASA IONICS. As a result, the BET specific surface area was 2,360 m ² /g, and the amount of mesopores (V ₁ ) 0.52 cc/g, and the pore volume (V ₂ ) is 0.88 cc/g, and V ₁ /V ₂ =0.59.

[Modulation of Activated Carbon 2]

The phenol resin was carbonized in a calciner at 600°C for 2 hours under a nitrogen atmosphere, then pulverized with a ball mill, and classified to obtain carbides with an average particle diameter of 7.0 μm. This carbide and KOH were mixed at a mass ratio of 1:5, and heated in a calciner at 800° C. for 1 hour in a nitrogen atmosphere to perform activation. After that, after stirring and washing for 1 hour in dilute hydrochloric acid adjusted to a concentration of 2 mol/L, it was washed with distilled water until the pH stabilized between 5 and 6, and then dried to obtain activated carbon 2.

For this activated carbon 2, the average particle size was 7.1 μm, the BET specific surface area was 3,627 m ² /g, the mesopore volume (V ₁ ) was 1.50 cc/g, and micro The pore volume (V ₂ ) was 2.28 cc/g, and V ₁ /V ₂ =0.66.

<Manufacture of positive electrode precursor>

[Production Examples 1-1 to 1-8 (Manufacture of positive electrode precursors 1 to 8)]

(Preparation of positive electrode coating solution)

For the positive electrode active material, use the types and amounts of activated carbon and lithium transition metal oxides listed in Table 1, and mix the lithium compounds, conductive fillers, and binders other than the positive electrode active materials of the types and amounts described in Table 1. And a dispersion stabilizer and distilled water to obtain a mixture in which the mass ratio of the solid content is the value described in Table 1, respectively. Using a film spinning high-speed mixer "FILMIX" manufactured by PRIMIX, the resulting mixture was dispersed at a peripheral speed of 17.0 m/s to obtain a positive electrode coating solution. In addition, in Production Examples 1-1, 1-2, and 1-4 to 1-8, the lithium transition metal oxide was not used in the preparation of the coating liquid.

In Production Examples 1-8, lithium compounds other than the positive electrode active material were not used.

<Manufacture of positive electrode precursor>

By using an extrusion coating machine made by TORAY ENGINEERING Co., Ltd., the obtained positive electrode coating liquid was applied to the positive electrode collector at a coating speed of 1 m/s One or both sides of the aluminum foil with a thickness of 15 μm are dried at a drying temperature of 100° C., and then pressed using a roller press under the conditions of a pressure of 4 kN/cm and a surface temperature of the pressing part of 25° C. to obtain a positive electrode precursor .

The thickness of the positive electrode active material layer of the positive electrode precursor is adjusted to about 60 μm on each side. The thickness of the positive electrode active material layer is measured by using a film thickness gauge Linear Gauge Sensor GS-551 made by Ono Measuring Instruments Co., Ltd. to measure any 10 positions of the obtained positive electrode precursor, and deducted from the average value of the measured thickness The thickness of the aluminum foil of the positive electrode current collector is obtained.

The abbreviations of the ingredients in Table 1 have the meanings listed below.

[Lithium compound other than positive electrode active material]

Li carbonate: Lithium carbonate with an average particle size of 2.26 μm obtained in <Pulverization of Lithium Carbonate>

[Lithium transition metal oxide]

LiFePO _4: average particle diameter of 3.5μm LiFePO ₄

[Binder]

PAcNa: sodium polyacrylate

PAcEst: polyacrylate

SBR: Styrene-butadiene rubber

"-" in Table 1 indicates that the components in this column are not used.

[Production Examples 1-9 to 1-14 (Production of positive electrode precursors 9 to 14)]

For the positive electrode active material, use the types and amounts of carbon materials and lithium transition metal oxides listed in Table 2, and further mix lithium compounds, conductive fillers, and binders other than the positive electrode active materials of the types and amounts described in Table 2. , And dispersion stabilizer, and distilled water to obtain a mixture with a solid content mass ratio of 43.0%. The coating liquid was prepared by dispersing the obtained mixture at a peripheral speed of 17 m/s for 3 minutes using a film spinning high-speed mixer "FILMIX (registered trademark)" manufactured by PRIMIX.

In addition, in Production Examples 1-9 and 1-11 to 1-13, the lithium transition metal oxide was not used in the preparation of the coating liquid.

Using an extrusion coating machine made by Toray Engineering Co., Ltd., the above coating liquid was applied to one or both sides of an aluminum foil with a thickness of 15 μm as a positive electrode current collector at a coating speed of 1 m/s. And increase the temperature of the drying furnace in the order of 50℃, 70℃, 90℃, 110℃ After drying, and further drying with an IR heater, using a roller press under a pressure of 6kN/cm and the surface temperature of the pressurized part at 25°C, it was manufactured on one or both sides of the positive electrode current collector Cathode precursors 9-14 with a cathode active material layer.

[Production Examples 1-15 to 1-17 (Production of positive electrode precursors 15 to 17)]

For the positive electrode active material, use the carbon materials of the types and amounts described in Table 2, and further mix lithium compounds other than the positive electrode active materials of the types and amounts described in Table 2, conductive fillers, dispersion stabilizers, and distilled water. The film spinning high-speed mixer "FILMIX (registered trademark)" manufactured by PRIMIX Corporation disperses the resulting mixture at a peripheral speed of 17 m/s for 3 minutes.

Thereafter, by further adding the type and amount of binder described in Table 2, and stirring using the mixer "Defoaming Taro" manufactured by THINKY, a coating solution with a mass ratio of the solid content of 43.0% was obtained .

In addition, in Production Examples 1-17, lithium compounds other than the positive electrode active material were not used in the preparation of the coating liquid.

Except for using the above-mentioned coating liquid, all are the same as those in Production Example 1-1, and cathode precursors 15 to 17 each having a cathode active material layer on one or both surfaces of the cathode current collector are manufactured.

The abbreviations of the ingredients in Table 2 have the meanings listed below.

[Lithium compound other than positive electrode active material]

Li carbonate: lithium carbonate with an average particle size of 2.4 μm

Li oxide: lithium oxide with an average particle size of 2.4 μm

Li hydroxide: lithium hydroxide with an average particle size of 2.4 μm

[Lithium transition metal oxide]

LiFePO _4: average particle diameter of 3.5μm LiFePO ₄

LiNiCoAlO: LiNi _0.80 Co _0.15 Al _0.05 O _{2 with} an average particle size of 3.5 μm

[Binder]

PAcNa: sodium polyacrylate

SBR: Styrene-butadiene rubber

[Dispersion stabilizer]

CMC: carboxymethyl cellulose

"-" in Table 2 indicates that the components in this column are not used.

<Preparation of negative active material>

[Modulation of composite carbon material 1a]

As a base material, 150 g of commercially available coconut shell activated carbon having an average particle diameter of 3.0 μm and a BET specific surface area of 1,780 m ² /g was placed in a cage made of stainless steel mesh and placed in coal containing a carbonaceous material precursor It is made of stainless steel tank (bat) of 270g of asphalt (softening point: 50°C), and the two are installed in an electric furnace (effective size in the furnace 300mm×300mm×300mm). In a nitrogen environment, the temperature was raised to a heat treatment temperature of 600°C for 8 hours, and the same temperature was maintained for 4 hours to allow the two to thermally react to obtain a composite carbon material 1a. After cooling the composite carbon material 1a to 60°C by natural cooling, it was taken out from the furnace.

With respect to the obtained composite carbon material 1a, the average particle diameter and the BET specific surface area were measured in the same manner as the activated carbon 1 described above. As a result, the average particle diameter was 3.2 μm, and the BET specific surface area was 262 m ² /g. The mass ratio of carbonaceous materials derived from coal-based pitch to activated carbon is 78%.

[Modulation of Composite Carbon Materials 1b and 2a]

Except that the type and amount of the base material, the amount of coal-based pitch as the precursor of the carbonaceous material, and the heat treatment temperature are changed to those shown in Table 3, the other steps are the same as [Modulation of Composite Carbon Material 1a]. Thus, composite carbon materials 1b and 2a are prepared.

The same measurement as the composite carbon material 1a was performed, and the measured average particle diameter and BET specific surface area, and the mass ratio of the carbonaceous material derived from coal-based pitch to activated carbon are combined and shown in Table 3.

<Manufacture of negative electrode>

[Production Example 2-1 (Production of Negative Electrode 1)]

The composite carbon material 1a is used as a negative electrode active material to produce a negative electrode.

85 parts by mass of composite carbon material 1a, 10 parts by mass of acetylene black as a conductive filler, and 5 parts by mass of PVdF (polyvinylidene fluoride) as a binder, and NMP (N-methylpyrrolidone) were mixed to obtain a mixture , A film spinning high-speed mixer "FILMIX" manufactured by PRIMIX was used to disperse the resulting mixture at a peripheral speed of 15 m/s to obtain a negative electrode coating solution.

The viscosity (ηb) and TI value of the obtained negative electrode coating solution were measured using Toki Industries Co., Ltd.'s E-type viscometer "TVE-35H". As a result, the viscosity (ηb) was 2,789 mPa. s, thixotropic index (TI) value is 4.3.

Using an extrusion coating machine manufactured by Toray Engineering Co., Ltd., the resulting coating liquid was applied to an electrolytic copper foil with a thickness of 10 μm as a negative electrode current collector at a coating speed of 1 m/s. After drying on both sides at a drying temperature of 85°C, a negative pressure was produced by using a roller press under the conditions of a pressure of 4 kN/cm and a surface temperature of the pressing portion of 25°C.

The thickness of the negative electrode active material layer of the obtained negative electrode 1 is measured at any 10 places of the negative electrode 1 by using a film thickness gauge Linear Gauge Sensor GS-551 manufactured by Ono Measuring Instruments Co., Ltd., and subtracted from the average value of the measured thicknesses Obtained from the thickness of electrolytic copper foil. As a result, the thickness of the negative electrode active material layer of the negative electrode 1 was 40 μm per side.

<Production Examples 2-2 and 2-3 (Production Examples of Negative Electrodes 2 and 3)>

Except that the types and amounts of the negative electrode active material, the conductive filler, and the binder were changed as described in Table 4, the others were the same as those in Production Example 2-1, and production and evaluation of the negative electrodes 2 and 3 were performed. The results are shown in Table 4.

[Production Example 2-4 (Production of Negative Electrode 4)]

86 parts by mass of the negative electrode active material of the composite carbon material 1a, 10 parts by mass of acetylene black as the conductive filler, and 2 parts by mass of CMC (carboxymethyl cellulose) as the dispersion stabilizer, and steam Distilled water was mixed to obtain a mixture, and a film-spindle high-speed mixer "FILMIX (registered trademark)" manufactured by PRIMIX was used to disperse the resulting mixture at a peripheral speed of 15 m/s. Then, by further adding 2 parts by mass of SBR (styrene-butadiene rubber) as a binder, and stirring using a mixer "Defoaming Taro" manufactured by THINKY, the mass ratio of the solid content was 39.0 % Of the coating liquid.

Using an extrusion coating machine manufactured by Toray Engineering Co., Ltd., apply the above coating liquid to both sides of an electrolytic copper foil with a thickness of 10 μm as a negative electrode collector at a coating speed of 1 m/s, and After drying at a drying temperature of 70° C., a negative pressure was produced by using a roller press under the conditions of a pressure of 4 kN/cm and a surface temperature of the pressing portion of 25° C.

[Production Example 2-5 (Production of Negative Electrode 5)]

The negative electrode 5 is manufactured except that the composite carbon material 2a is used as the negative electrode active material.

[Production Example 2-6 (Production of Negative Electrode 6)]

86 parts by mass of composite carbon material 2a as a negative electrode active material, 10 parts by mass of acetylene black as a conductive filler, 2 parts by mass of sodium polyacrylate as a binder, and CMC (carboxymethyl cellulose) as a dispersion stabilizer 2 parts by mass and distilled water were mixed to obtain a mixture having a solid content mass ratio of 39.0%. A film spinning type high-speed mixer "FILMIX (registered trademark)" manufactured by PRIMIX was used to disperse the resulting mixture at a peripheral speed of 15 m/s to obtain a coating liquid.

The negative electrode 6 is manufactured in the same manner as in the production of the negative electrode 4 in Production Example 2-4, except that the above coating liquid is used.

【Table 4】

The raw materials in Table 3 and Table 4 are as follows: Coconut shell activated carbon: average particle size 3.0 μm, BET specific surface area 1,780 m ² /g

Carbon nanoparticles: average particle size 5.2 μm, BET specific surface area 859 m ² /g, primary particle size 20 nm

Artificial graphite: average particle size 4.8 μm, BET specific surface area 3.1 m ² /g

Coal-based asphalt: softening point 50℃

PVdF: polyvinylidene fluoride

CMC: carboxymethyl cellulose

SBR: Styrene-butadiene rubber

<Preparation of non-aqueous electrolytes 1~3>

[Preparation Example 3-1~3-3 (Preparation of Non-aqueous Electrolyte 1~3)]

The lithium salt electrolyte described in Table 5 was dissolved in a mixed solvent composed of the types and amounts of organic solvents described in Table 5 to obtain nonaqueous electrolyte solutions 1 to 3, respectively.

The abbreviations of the ingredients in Table 5 have the meanings listed below.

[Cyclic carbonate]

EC: Ethyl carbonate

PC: propylene carbonate

[Chain carbonate]

DMC: dimethyl carbonate

EMC: ethyl methyl carbonate

DEC: diethyl carbonate

[Preparation Example 3-4~3-15 (Preparation of Non-aqueous Electrolyte 4~15)]

For the non-aqueous solvent, use the mixed solvent of cyclic carbonate and chain carbonate of the type and amount described in Table 6, and dissolve the additive and lithium salt of the type and amount of Table 6 in the mixed solvent. To obtain non-aqueous electrolytes 4~15 respectively.

The amount of the lithium salt described in Table 6 is the concentration of the lithium salt in the obtained non-aqueous electrolyte.

In Preparation Examples 3-4 to 3-9 and 3-12 to 3-15, no fluorine-containing compounds were used.

The abbreviations of the ingredients in Table 6 have the meanings listed below.

[Cyclic carbonate]

EC: Ethyl carbonate

PC: propylene carbonate

[Chain carbonate]

EMC: ethyl methyl carbonate

DEC: diethyl carbonate

DMC: dimethyl carbonate

[Fluorine compound]

PEC: fluoroethylene carbonate

FE: HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H

"-" in Table 6 indicates that the components in this column are not used.

≪Example 1-1≫

<Manufacture of non-aqueous lithium storage elements>

[Assembly]

In Example 1-1, a separator composed of the following two layers was used: On one side of a microporous membrane made of polyethylene (PE) with a thickness of 15 μm, a coating containing gibbsite (AlOOH) fine particles with a thickness of 5 μm was formed.

The obtained 21 double-sided negative electrodes 1, 20 double-sided positive electrode precursors 1, and 2 single-sided positive electrode precursors 1, were cut into 10 cm×10 cm (100 cm ² ), respectively. At the top and bottom, the single-sided positive electrode precursor 1 is used and the positive electrode active material layer is disposed on the inside. Between them, 21 double-sided negative electrode precursors 1 and 20 double-sided positive electrode precursor precursors 1 are used alternately. The porous membrane separator is sandwiched between the negative electrode and the positive electrode precursor adjacent in the stacking direction and stacked. Furthermore, after connecting the negative electrode terminal and the positive electrode terminal to the negative electrode and the positive electrode precursor by ultrasonic welding, vacuum drying was performed under the conditions of a temperature of 80° C., a pressure of 50 Pa, and a drying time of 60 hr to obtain an electrode laminate.

In a dry environment with a dew point of -45°C, store the dried electrode laminate in an outer body composed of an aluminum laminate packaging material, and connect the positive and negative terminals and the bottom of the outer body to 3 sides at a temperature of 180°C 1. Heat sealing under the condition of sealing time 20sec and sealing pressure 1.0MPa.

[Liquid injection, impregnation, and sealing]

In a dry air environment with a temperature of 25°C and a dew point of -40°C or lower, about 80g of non-aqueous electrolyte 1 is injected into the electrode laminate contained in the aluminum laminate package at atmospheric pressure to form Water-based lithium storage element. Next, the non-aqueous lithium electric storage element was placed in a decompression chamber, decompressed from normal pressure to -87 kPa, then returned to normal pressure, and allowed to stand for 5 minutes. After repeating the operation of depressurizing the atmospheric pressure to -87 kPa for 4 times and returning to the atmospheric pressure again, it was allowed to stand at atmospheric pressure for 15 minutes. Further reduce the pressure from normal pressure to -91kPa and then return to normal pressure. Repeat the same decompression and return to normal pressure a total of 7 times (at this time, decompress from normal pressure to -95, -96, -97, -81, -97, -97, -97 kPa, respectively). By the above procedure, the non-aqueous electrolyte 1 is impregnated into the electrode laminate of the non-aqueous lithium electricity storage element.

Seal the aluminum by placing the outer body of the electrode laminate containing the impregnated non-aqueous electrolyte 1 in a decompression sealer, decompressed to -95kPa, 180°C, 0.1MPa for 10 seconds The packaging material is laminated to obtain a non-aqueous lithium electricity storage element.

<RED value of the polymer constituting the binder relative to the non-aqueous electrolyte>

The sodium polyacrylate constituting the polymer of the binder in the positive electrode active material layer has a RED value of 2.48 relative to the non-aqueous electrolyte 1. In addition, the RED value is obtained by the method described in Patent Document 4. The RED values obtained are shown in Table 7.

[Lithium doping]

The obtained non-aqueous lithium power storage element was initially charged by the following method, and the negative electrode was doped with lithium: using a charge and discharge device manufactured by TOYO SYSTEM Co., Ltd. (TOSCAT-3100U), under the environment of 25 ℃, constant current charging at a current value of 50mA until the voltage is 4.5V, and then continue to conduct constant voltage charging at 4.5V for 72 hours.

[Ageing]

The non-aqueous lithium storage element doped with lithium was subjected to a constant current discharge at 1.0A under a 25°C environment until the voltage was 3.0V, and then a constant voltage discharge at 3.0V was performed for 1 hour to adjust the voltage to 3.0V. The non-aqueous lithium power storage element was stored in a thermostatic bath at 60°C for 60 hours to be aged.

[exhaust]

In a dry air environment with a temperature of 25°C and a dew point of -40°C, part of the aluminum laminate packaging material of the non-aqueous lithium storage element after aging is unsealed. Next, put a part of the non-aqueous lithium storage element after the opening of the aluminum laminated packaging material in the decompression chamber, and use the diaphragm pump (N816.3KT.45.18) made by KNF Company, and repeat the process for 3 minutes. After reducing the pressure to -80kPa, it took another 3 minutes to return to normal pressure, a total of 3 times. The non-aqueous lithium storage element was placed in a decompression sealer, decompressed to -90 kPa, and then sealed at a temperature of 200°C and a pressure of 0.1 MPa for 10 seconds to seal (reseal) the aluminum laminate packaging material.

By the above procedure, non-aqueous lithium electricity storage elements are manufactured.

<Measurement and evaluation of non-aqueous lithium storage devices>

[Adopting of separators]

After adjusting the voltage of the obtained non-aqueous lithium storage element to 2.9V, disassemble it in an argon (Ar) box installed in a room set at 23°C and managed at a dew point of -90°C or less and an oxygen concentration of 1 ppm or less, and take out the partition Pieces. After the separator taken was immersed in ethyl methyl carbonate (MEC) at 100 times the mass of the separator for more than 10 minutes, the MEC was replaced and the separator was immersed again. After that, the separator was taken out from the MEC and vacuum-dried in the side box of the Ar box under the conditions of room temperature and pressure of 10 kPa Dry for 2 hours.

[Determination of shrinkage of separator]

The parallel direction and the vertical direction with respect to one side of the original separator were made into their respective sides, and after vacuum drying, the separator was cut into a slightly square shape of about 8 cm×8 cm.

For the cut-out separator, measure the length before heating in the following manner.

The length passing through the center of the approximately square-shaped separator and perpendicular to one side was measured as L1a, and L1a=80.3 mm. Next, the length passing through the center of the separator and perpendicular to the direction of L1a is measured as L1b, and L1b=79.9 mm. The average value L1a and L1b of these L1a and L1b is (L1a+L1b)/2=80.2 mm, which is the length of the separator before heating.

Next, in an unconstrained state, the cut separator was placed in a fixed-air dryer (model: DRS4200DA, manufactured by ADVANTEC) set at 120°C for 1 hour. For the separator kept for 1 hour, measure L2a and L2a in the same way as L1a and L1b, respectively, and calculate the average value L2, L2=(L2a+L2b)/2=78.6mm.

Using the obtained L1 and L2, the shrinkage ratio was calculated, and the shrinkage ratio of the separator of Example 1-1 was (L1-L2)/L1=0.02.

[Determination of air permeability of separator after keeping at 120℃ for 1 hour]

For the separator after measuring the shrinkage, a gurley type air permeability tester (Toyo Seiki, G-B2 (trademark)) conforming to JIS P-8117 was used, and the air permeability P was measured under the following conditions.

Inner tube quality: 567g

Ventilation surface diameter: 28.6mm

Ventilation area: 645mm ²

The air permeability P of the separator after keeping it at 120°C for 1 hour in Example 1-1 was 96 seconds/100 mL.

[Determination of withstand voltage of separator]

After vacuum drying, the separator is taken, and a square shape of about 3 cm×3 cm is cut out. Use withstand voltage. An insulation resistance tester (manufactured by Kikusui Electronics Industry, model: TOS9201) determines the withstand voltage of the cut-out separator. At this time, the separator is sandwiched between the electrode of the SUS plate and the electrode terminal of 5 mmφ, and the voltage between the two electrodes is boosted at a rate of 0.25 kV/sec, and the voltage at which the current of 0.2 mA flows is determined as the resistance Voltage.

The withstand voltage of the separator of Example 1-1 was 0.91kV.

[Measurement of discharge capacity Q at Vmax=3.8V, Vmin=2.2V]

The discharge capacity Q of Example 1-1 was measured at Vmax=3.8V and Vmin=2.2V. For the obtained non-aqueous lithium storage element, use a charge and discharge device (5V, 360A) made by FUJITSU TELECOM NETWORKS LIMITED in a thermostat set at 25°C with a current value of 20C Charging at a constant current up to 3.8V, followed by constant voltage charging with a constant voltage of 3.8V applied for a total of 30 minutes. Next, the discharge capacity Q was measured by performing constant current discharge at a current value of 2C up to 2.2V.

The discharge capacity Q of the non-aqueous lithium electricity storage device of Example 1-1 at Vmax=3.8V and Vmin=2.2V was 895mAh.

[Calculation of normal temperature discharge internal resistance Ra at Vmax=3.8V, Vmin=2.2V]

The internal resistance Ra of the initial normal temperature discharge of Example 1-1 was measured at Vmax=3.8V and Vmin=2.2V. For the obtained non-aqueous lithium storage element, use a charge and discharge device (5V, 360A) made by Fujitsu Telecom Network Co., Ltd. in a thermostat set at 25°C, and charge it at a constant current of 3.8V at a current value of 20C Then, constant voltage charging with a constant voltage of 3.8 V applied for a total of 30 minutes. Next, constant current discharge was carried out at a current value of 20C until 2.2V, and a discharge curve (time-voltage) was obtained. In this discharge curve, the voltage value at the time point of the discharge time of 1 second and 2 seconds is approximated by a straight line. The voltage of the discharge time = 0 seconds is set to E ₀ , and according to the reduced voltage △E=3.8-E ₀ , and R=△E/(20C (current value A)), calculate the internal resistance Ra at room temperature discharge.

The non-aqueous lithium electricity storage device of Example 1-1 had an internal resistance Ra at normal temperature discharge of 1.49 mΩ.

[3.5V micro short circuit check test]

The obtained non-aqueous lithium storage element was discharged at a constant current of 2.5 mA at a current value of 100 mA, and then charged at a constant current of 100 mA at a current value of 3.5 V, and then charged at a constant voltage of 3.5 V for 2 hours. Adjust to 3.5V. Next, the electrode body was allowed to stand for 1 week in a thermostat set at 25° C. while being pressurized with a pressure of 10 kPa. The voltage is 3.2V, and there is no micro short circuit.

<Calculation of Rd/Ra>

The obtained non-aqueous lithium power storage device was subjected to the above-mentioned measurement of the low-temperature discharge internal resistance Rd, and the Rd/Ra was calculated by dividing the normal-temperature discharge internal resistance Ra at 3.8V. Place the non-aqueous lithium storage element in a thermostat set at -30°C for 2 hours. Using a charge-discharge device (5V, 360A) made by Fujitsu Telecommunications Network Co., Ltd. with a constant temperature bath maintained at -30°C, charge a constant current up to 3.8V at a current value of 1.0C, and then apply 3.8V The charging at a constant voltage for a total of 2 hours. Next, constant current discharge was carried out at a current value of 10C until 2.2V, and a discharge curve (time-voltage) was obtained. In this discharge curve, the voltage value at the time point of the discharge time of 2 seconds and 4 seconds is approximated by a straight line. The voltage of the discharge time = 0 seconds is set to Eo, and according to the reduced voltage △E=3.8-Eo, and Rd=△E/(10C (current value A)) Calculate Rd. Divide this Rd by the normal temperature discharge internal resistance Ra at 3.8V above, Rd/Ra=12.3.

[Measurement of discharge capacity Q at Vmax=4.1V, Vmin=2.2V]

For the obtained non-aqueous lithium storage element, the discharge capacity Q at Vmax=4.1V and Vmin=2.2V was measured. For the obtained non-aqueous lithium storage element, use a charge and discharge device (5V, 360A) manufactured by Fujitsu Telecommunications Network Co., Ltd. in a thermostat set at 25°C, and charge at a constant current with a current value of 20C until 4.1V Then, a constant voltage charging with a constant voltage of 4.1V applied for a total of 30 minutes. Next, the discharge capacity Q was measured by performing constant current discharge at a current value of 2C up to 2.2V.

The discharge capacity Q of the non-aqueous lithium electricity storage device of Example 1-1 at Vmax=4.1V and vmin=2.2V was 1063mAh.

[Calculation of internal resistance Ra at room temperature discharge at Vmax=4.1V, Vmin=2.2V]

For the obtained non-aqueous lithium power storage device, the internal resistance Ra at room temperature discharge when Vmax=4.1V and Vmin=2.2V was measured. For the obtained non-aqueous lithium storage element, use a charge and discharge device (5V, 360A) manufactured by Fujitsu Telecommunications Network Co., Ltd. in a thermostat set at 25°C, and charge at a constant current with a current value of 20C until 4.1V Then, a constant voltage charging with a constant voltage of 4.1V applied for a total of 30 minutes. Next, constant current discharge was carried out at a current value of 20C until 2.2V, and a discharge curve (time-voltage) was obtained. In this discharge curve, the voltage value at the time point of the discharge time of 1 second and 2 seconds is approximated by a straight line. The voltage of the discharge time = 0 seconds is set to E ₀ , according to the reduced voltage △E=4.1-E ₀ , And R=△E/(20C (current value A)), calculate the internal resistance Ra at room temperature discharge.

The non-aqueous lithium electric storage element of Example 1-1 had an internal resistance Ra at normal temperature discharge of 1.48 mΩ.

[4.1V micro short circuit check test]

The obtained non-aqueous lithium storage element was discharged at a constant current of 3.5 mA at a current value of 100 mA, and then charged at a constant current at a current value of 100 mA until a voltage of 4.1 V, followed by continuous charging at a constant voltage of 4.1 V for 2 hours, and the voltage Adjust to 4.1V. Next, the electrode body was allowed to stand for 24 hours in a thermostat set at 25° C. while being pressurized with a pressure of 10 kPa. The voltage is 4.05V, no micro short circuit occurred.

[Calculation of Rb after high temperature storage test 1, and calculation of Rb/Ra]

The obtained non-aqueous lithium power storage device was subjected to the high-temperature storage test 1 described above. Charge the non-aqueous lithium storage element in a thermostat set at 25°C using a charge-discharge device (5V, 360A) manufactured by Fujitsu Telecom Network Co., Ltd. at a constant current of 100C until 4.0V, then Constant voltage charging with a constant voltage of 4.0V applied for 10 minutes in total. Next, the storage element was stored in an environment of 85°C, and it was taken out from the environment of 85°C every 2 weeks, and after charging the cell voltage to 4.0V by the same charging operation, the unit was returned to the environment of 85°C for further storage. Repeat this operation for 1,000 hours to carry out the high-temperature storage test of the non-aqueous power storage device. For the storage element after the high-temperature storage test, the normal-temperature discharge internal resistance Rb after the high-temperature storage test was calculated in the same manner as the above [calculation of the normal-temperature discharge internal resistance Ra at Vmax=3.8V, Vmin=2.2V]. Divide this Rb(Ω) by the above-obtained normal temperature discharge internal resistance Ra(Ω) before Vmax=3.8V and Vmin=2.2V obtained before the high temperature storage test to calculate the ratio Rb/Ra, the ratio Rb/Ra is 1.15 .

[Calculation of Rb after high temperature storage test 4 and calculation of Rb/Ra]

The obtained non-aqueous lithium electricity storage device was subjected to the high-temperature storage test 4 described above. Charge the non-aqueous lithium storage element in a constant temperature bath set at 25°C using a charge and discharge device (5V, 360A) made by Fujitsu Telecom Network Co., Ltd. at a constant current of 100C until 4.1V, then Constant voltage charging with a constant voltage of 4.1V applied for 10 minutes in total. Then, store the storage element in an environment of 85°C, take it out from the environment of 85°C every 2 weeks, and charge the cell voltage to 4.1V with the same charging operation, and then put the unit back in the environment of 85°C to continue storage. Repeat this operation for 1,000 hours to carry out the high-temperature storage test of the non-aqueous power storage device. For the storage element after the high-temperature storage test, the calculation is based on the internal resistance Ra at room temperature under the above [Vmax=4.1V, Vmin=2.2V Out] The internal resistance Rb at room temperature after the high temperature storage test is calculated in the same way. Divide this Rb(Ω) by the internal resistance Ra(Ω) at room temperature before Vmax=4.1V and Vmin=2.2V obtained before the high-temperature storage test, to calculate the ratio Rb/Ra, the ratio Rb/Ra is 1.32 .

"Examples 1-2~1-16 and Comparative Examples 1-1~1-6"

Except that the positive electrode precursor, the negative electrode, the separator, and the non-aqueous electrolyte were changed to those shown in Table 7, the others were the same as in Example 1-1, and non-aqueous lithium electricity storage devices were separately manufactured and subjected to various evaluations. . As separators, Examples 1-2 to 1-7 and 1-14 to 1-16, and Comparative Examples 1-1 to 1-3 and 1-6 were made of polyethylene micro-thickness described in Table 7 On the porous membrane, a separator composed of two layers having a coating layer of the type and thickness described in Table 7 was formed. In Examples 1-8 to 1-10 and 1-14, and Comparative Examples 1-4 and 1-5, single-layer separators made of polyethylene microporous membranes having the thicknesses described in Table 7 were used. In Examples 1-11, a three-layer separator composed of a polypropylene microporous membrane, a polyethylene microporous membrane, and a polypropylene microporous membrane was sequentially laminated. In Examples 1-12 and 1-13, a separator made of cellulose was used.

The evaluation results of the obtained non-aqueous lithium electricity storage device are collectively shown in Table 7 and Table 8.

The abbreviations of the microporous membranes and coatings in the partition column in Table 7 refer to those listed below.

(Microporous membrane)

PE: Microporous membrane made of polyethylene

PP/PE/PP: Lamination of polypropylene microporous membrane, polyethylene microporous membrane, polypropylene microporous membrane, and a three-layer separator with a thickness of 20 μm in order

Cellulose: cellulose non-woven paper

(coating)

AlOOH: coating containing fine particles of diaspore (AlOOH)

Polyaramid: coating containing polyaramid resin

"-" in Table 8 indicates that the column cannot be evaluated by micro-short circuit.

According to the above examples, the following non-aqueous lithium electricity storage elements are known, showing High capacity and low resistance at 25°C: the positive electrode contains a lithium compound other than the positive electrode active material, and the positive electrode binder has a RED value of 1 or more calculated from the Hansen solubility parameter of the non-aqueous electrolyte, and The internal resistance increase rate Rb/Ra is still 3.0 or less even when stored at 85° C. and 4.0 V at high temperature, which shows that it has excellent high-temperature durability.

Regarding Comparative Examples 1-4 and 1-5 in which the shrinkage ratio of the separator (L1-L2)/L1 was large, it was found that a micro short circuit occurred in the 3.5 V micro short circuit inspection test after the completion of the unit. This is because the non-aqueous lithium storage element is exposed to 60°C after the aging step before the completion of the unit, so the separator with a larger shrinkage shrinks more than the width of the positive and negative electrodes, causing contact between the positive and negative electrodes, resulting in a micro short circuit .

In addition, Examples 1-1 to 1-11 and 1-14 to 16 showed high capacity and low resistance even at Vmax=4.1V, and the interior was preserved by high temperature even at 85°C and 4.1V The resistance increase rate Rb/Ra is still 3.0 or less, and it is known that it has excellent high voltage and high temperature durability. On the other hand, in Examples 1-12 and 1-13, it was found that it was a micro short circuit in the micro short circuit inspection test at 4.1V. This is due to the use of a cellulose separator with a low withstand voltage. Therefore, at a high voltage of 4.1V, the insulation of the separator is damaged.

In addition, in Examples 1-1 to 1-16, the value Rd/Ra obtained by dividing the low-temperature discharge internal resistance Rd at -30°C by the normal-temperature discharge internal resistance Ra at 25°C and 3.8V is 15 or less, It is known that low resistance can be exhibited even at a low temperature of -30°C. Although this principle is not clear, it should be that the positive electrode contains a binder with a RED value of less than 1, so the interaction between the two is low, plus the lithium compound is separated from the positive electrode by the lithium doping step The multiplication effect of the gap generated by the active material layer improves the ion mobility in the positive electrode active material layer.

Through the above examples, it has been verified that the non-aqueous lithium electricity storage device of this embodiment type exhibits a high capacity, excellent initial output characteristics, and excellent high-temperature storage durability. Electrical components.

"Example 2-1"

<Manufacture of non-aqueous lithium storage elements>

[Assembly and drying of non-aqueous lithium storage elements]

The resulting 21 pieces of double-sided negative electrode 4, 20 pieces of double-sided positive electrode precursor 9 and 2 pieces of single-sided positive electrode precursor 9 were each cut into 10 cm×10 cm (100 cm ² ). On the top and bottom, single-sided positive electrode precursor 9 is used, and the positive electrode active material layer is arranged on the inside. 21 pieces of double-sided negative electrode 4 and 20 pieces of double-sided positive electrode precursor 9 are alternately used between A 15 μm cellulose separator is laminated between the negative electrode and the positive electrode precursor adjacent in the stacking direction. Furthermore, after connecting the negative electrode terminal and the positive electrode terminal to the negative electrode and the positive electrode precursor by ultrasonic welding, vacuum drying was performed under the conditions of a temperature of 80° C., a pressure of 50 Pa, and a drying time of 60 hr to obtain an electrode laminate.

In a dry environment with a dew point of -45°C, store the dried electrode laminate in an outer body composed of an aluminum laminate packaging material, and connect the positive and negative terminals and the bottom of the outer body to 3 sides at a temperature of 180°C 1. Heat sealing under the condition of sealing time 20sec and sealing pressure 1.0MPa.

[Injection, impregnation, and sealing of storage elements]

In a dry air environment with a temperature of 25°C and a dew point of -40°C or lower, about 80g of non-aqueous electrolyte 4 is injected into the electrode laminate contained in the aluminum laminate package at atmospheric pressure to form a non-lithium non-treatment Water-based lithium storage element. Next, the non-aqueous lithium electricity storage element was placed in a decompression chamber, reduced from normal pressure to -87 kPa, then returned to normal pressure, and allowed to stand for 5 minutes. After repeating the operation of depressurizing the normal pressure to -87 kPa for 4 times and returning to the normal pressure again, the power storage element was allowed to stand under normal pressure for 15 minutes. Further, after reducing the pressure from normal pressure to -91 kPa, the pressure was returned to normal pressure. Repeat the same decompression and then return to normal pressure for a total of 7 times (at this time, decompress from normal pressure to -95, -96, -97, -81, -97, -97, and -97kPa). By the above procedure, the non-aqueous electrolyte is impregnated into the electrode laminate of the non-aqueous lithium electricity storage element.

Thereafter, by placing the outer body of the electrode laminate containing the non-aqueous electrolyte impregnated into a decompression sealer, the pressure is reduced to -95 kPa, 180°C, 0.1 MPa, and sealed for 10 seconds. The aluminum laminate packaging material was sealed to obtain a non-aqueous lithium electricity storage element.

[RED value of the polymer constituting the binder relative to the non-aqueous electrolyte]

Using the software HSPiP, the distance Rc between the Hansen solubility parameter of the polymer and the Hansen solubility parameter of the non-aqueous electrolyte, and the radius of interaction R0 of the radius of the dissolving ball of the polymer are calculated by the above method. Substitute the numerical value into the mathematical formula: RED=Rc/R0 to obtain the RED value of the polymer constituting the binder contained in the positive electrode precursor relative to the non-aqueous electrolyte 4. The results obtained are shown in Table 9.

[Lithium doping]

The obtained non-aqueous lithium storage element was initially charged by the following method, and the negative electrode was doped with lithium: a charge-discharge device (TOSCAT-3100U) manufactured by Toyo Systems Co., Ltd. was used under a 50°C environment with a current After constant current charging at a value of 0.5A until the voltage is 4.5V, the constant voltage charging at 4.5V is continued for 8 hours.

[Ageing]

The non-aqueous lithium storage element doped with lithium was subjected to a constant current discharge at 0.5A under a 25°C environment until the voltage was 3.5V, and then a constant current discharge at 3.5V was performed for 1 hour to adjust the voltage to 3.5V. Next, the non-aqueous lithium power storage element was stored in a thermostat at 60° C. for 60 hours to be aged.

[exhaust]

In a dry air environment with a temperature of 25°C and a dew point of -40°C, store the non-aqueous lithium battery after aging A part of the aluminum laminate packaging material is unsealed. Next, put a part of the non-aqueous lithium storage element after opening the aluminum laminate package in the decompression chamber, and use the diaphragm pump (N816.3KT.45.18) made by KNF Company to repeat the decompression from normal pressure to 3 minutes. After -80kPa, it takes 3 minutes to return to normal pressure for a total of 3 times. The non-aqueous lithium storage element was placed in a decompression sealer, decompressed to -90 kPa, and then sealed at a temperature of 200°C and a pressure of 0.1 MPa for 10 seconds to seal (reseal) the aluminum laminate packaging material.

By the above sequence, two non-aqueous lithium electricity storage elements are manufactured.

<Evaluation of non-aqueous lithium electricity storage device>

Of the two non-aqueous lithium storage elements obtained above, one of them is used to measure the cyclic voltammogram of the non-aqueous electrolyte, and the other is used for electrostatic capacity and Ra. It is used for measurement of F and high temperature storage test.

[Measurement of cyclic voltammogram of non-aqueous electrolyte]

Production of three-pole unit

Disintegrate the resulting non-aqueous lithium electricity storage element in an argon box with a dew point temperature of -72°C, and take out the non-aqueous electrolyte.

Next, an aluminum foil with a thickness of 15 μm was cut into 4 cm×8 cm (32 cm ² ) to produce a working electrode. The lithium metal foil with a thickness of 100 μm was cut into 4 cm×8 cm (for the counter electrode) and 1 cm×4 cm (for the reference electrode), and the counter electrode and the reference electrode were produced by crimping them separately to the SUS mesh. A microporous membrane separator with a thickness of 15 μm was sandwiched between the working electrode and the counter electrode and stacked. On the other hand, the reference electrode was covered with a microporous membrane separator with a thickness of 15 μm. The terminals are connected to the working electrode, the counter electrode, and the reference electrode by ultrasonic welding.

In a dry environment with a dew point of -45℃, the separator covering the reference electrode, the working electrode and The laminated body of the opposing electrode is stored in an exterior body made of an aluminum laminate package so that the two are in contact with each other side by side, and the terminal part and the bottom exterior body are three sides at a temperature of 180° C. and a sealing time Heat seal under the condition of 20sec and sealing pressure 1.0MPa.

In a dry air environment with a temperature of 25°C and a dew point of -40°C or lower, about 3 g of a non-aqueous electrolyte solution taken out of the above-mentioned non-aqueous lithium electricity storage element was injected into this aluminum laminate packaging material at atmospheric pressure to form a tripolar unit . Next, the triode unit was placed in a decompression chamber, reduced to -87 kPa from normal pressure, then returned to atmospheric pressure, and left to stand for 5 minutes to impregnate the laminate with the non-aqueous electrolyte.

Then, by placing the laminated body containing the non-aqueous electrolyte impregnated into the decompression sealer, the pressure is reduced to -95 kPa, the temperature is 180° C., and the pressure is 0.1 MPa for 10 seconds. The aluminum laminate packaging material was sealed to obtain a triode unit for cyclic voltammogram measurement.

Cyclic voltammetry

The obtained three-pole unit was measured in a thermostatic bath set at 25°C using an electrochemical measuring device manufactured by Solartron, and according to the above method, 3.8 V (vs. Li / Li ⁺⁾ above 4.8V (vs.Li/Li ⁺ per working) voltage range of the maximum current value of the reaction area of the electrode. The results obtained are shown in Table 9.

[Ra. Determination of F and E/V]

Example 2-1 of Ra. F and E/V were measured at Vmax=3.8V and Vmin=2.2V. For the obtained non-aqueous lithium storage element, use a charge and discharge device (5V, 360A) manufactured by Fujitsu Telecommunications Network Co., Ltd. in a thermostat set at 25°C, and calculate the electrostatic capacity F and 25°C according to the above method. Internal resistance Ra, and get Ra. F and energy density E/V. The results obtained are shown in Table 9.

[High temperature storage test 2]

For the obtained non-aqueous lithium power storage element, use a charge-discharge device (5V, 360A) manufactured by Fujitsu Telecommunications Network Co., Ltd. in a thermostat set at 25°C. Calculate the normal temperature interior after the high-temperature storage test according to the above method Resistance Rb, and get Rb/Ra. The results obtained are shown in Table 9.

"Examples 2-2~2-20 and Comparative Examples 2-1~2-4"

Except for using the positive electrode precursor, negative electrode, and non-aqueous electrolyte as shown in Table 9, the others are the same as in Example 2-1, and Examples 2-2 to 2-20 and Comparative Example 2-1 were prepared respectively ~2-4 non-aqueous lithium storage devices, and various evaluations. The evaluation results of the obtained non-aqueous lithium electricity storage device are shown in Table 9.

Moreover, in Comparative Example 2-1, since the positive electrode current collector was broken during the lithium doping step, various subsequent evaluations could not be performed.

"Comparative Example 2-5"

<Manufacture and Evaluation of Non-aqueous Lithium Power Storage Elements>

Except for using the above-mentioned positive electrode precursor 17, attaching a lithium metal foil equivalent to 211 mAh/g per unit mass of the negative electrode active material to the negative electrode on the surface of the negative electrode active material layer of the negative electrode 5, and the non-aqueous electrolyte solution 12, all the other In the same way as in Example 2-1, the assembly, injection, impregnation, and sealing of the non-aqueous lithium electricity storage element were performed.

Next, the non-aqueous lithium power storage element obtained above was stored in a thermostat at an ambient temperature of 45° C. for 72 hours, and lithium metal was ionized and doped into the negative electrode 5. The non-aqueous lithium electricity storage element after doping was subjected to the same aging as in Example 2-1 and exhausted to produce two non-aqueous lithium electricity storage elements and evaluated. The results are shown in Table 9.

【Table 9】

"-" in Table 9 indicates that the evaluation in this column has not been performed.

If referring to Table 9, the maximum reaction current value of the non-aqueous electrolyte exceeds 0.010 mA/cm ² , and/or, the comparative example 2-1 of the polymer constituting the binder relative to the non-aqueous electrolyte has a RED value of 1 or less 2-4, and the positive electrode does not contain a lithium compound other than the positive electrode active material in the storage element of Comparative Example 2-5, Ra. F and Rb/Ra are larger.

On the other hand, the positive electrode contains a lithium compound other than the positive electrode active material, and the polymer constituting the binder has a RED value greater than 1 with respect to the non-aqueous electrolyte, and the maximum reaction current value of the non-aqueous electrolyte is 0.010 mA/cm ² or less Example 2-1 ~ 2-20 of the storage element, Ra. F is smaller, and Rb/Ra is also smaller. By Ra. F is small, it can be seen that the internal resistance of these storage elements is low (that is, the input and output characteristics are high); from Rb/Ra is small, it can be seen that these storage elements also show excellent durability at high temperatures above 85°C .

The reason why the electricity storage device of the present invention exhibits such excellent characteristics is considered to be because it exhibits high input and output characteristics by imparting porosity derived from a lithium compound to the positive electrode, and the binder in the positive electrode is difficult to dissolve In non-aqueous electrolyte, even if stored at high temperature, it can suppress the swelling of the binder caused by the electrolyte, which can suppress the decrease in the strength of the positive electrode and maintain low resistance.

In addition, it can be presumed that by adjusting the composition of the non-aqueous electrolyte, a high-quality coating is formed on the surface of the positive electrode current collector when a high voltage is applied during lithium doping, thereby suppressing corrosion accompanied by elution of the positive electrode current collector, And the resulting increase in resistance and disconnection of the current collector makes it possible to obtain high input-output characteristics and excellent high-temperature durability.

<Example 3-1>

<Manufacture of positive electrode coating solution>

The active carbon 1 is used as a positive electrode active material to produce a positive electrode precursor 18.

First, using a planetary mixer at a speed of 20 rpm, 4.0 parts by mass of Ketjen Black and 32.0 parts by mass of lithium carbonate were dry mixed for 15 minutes. 42.0 parts by mass of activated carbon 1 was added to the dry mixture, followed by dry mixing at 20 rpm for 15 minutes. Next, 14.0 parts by mass of LiFePO ₄ with an average particle diameter of 3.5 μm as a lithium transition metal oxide was added to the dry mixture, and dry mixing was performed at a speed of 10 rpm for 5 minutes to obtain a powder mixture 1.

In another container, mix 2.0 parts by mass of CMC (carboxymethyl cellulose), 6.0 parts by mass of sodium polyacrylate, and distilled water to make the solid content (activated carbon 1, lithium carbonate, LiFePO ₄ , Ketjen black, CMC, And the total amount of sodium polyacrylate) is 43.0% by weight, and mixed solution 1 is obtained.

The mixed solution 1 was added to the powder mixture 1 obtained above in 5 portions, and mixed at a speed of 20 rpm for a total of 50 minutes. The obtained mixture was used FILMIX (registered trademark) made by PRIMIX, a film rotary high-speed mixer, while cooling with cooling water so that the temperature in the stirring vessel became 10°C, and at a peripheral speed of 20 m/s. Disperse for 3 minutes to obtain a positive electrode coating solution.

精機)公司製之粒度計測定所得之正極塗敷液1之分散度。其結果，粒度為22μm。於密閉容器中量取20g所得之正極塗敷液，並於25℃環境下靜置24小時後，再度測定黏度(ηb₂)及TI₂值，黏度(ηb₂)為1,670mPa．s，TI₂值為6.0，TI₂/TI₁為0.83、ηb₂/ηb₁為0.82。 The viscosity (ηb ₁ ) and TI ₁ value of the obtained positive electrode coating solution were measured using the E-type viscometer TVE-35H of Toki Industries Co., Ltd. in the above-mentioned method. As a result, the viscosity (ηb ₁ ) was 2,030 mPa. s, TI ₁ value is 7.2. In addition, use YOSHIMITSU SEIKI(

Seiki) A particle size meter made by the company measures the dispersion of the obtained positive electrode coating solution 1. As a result, the particle size was 22 μm. Measure 20g of the obtained positive electrode coating solution in a closed container and let it stand at 25°C for 24 hours, and then measure the viscosity (ηb ₂ ) and TI ₂ value again. The viscosity (ηb ₂ ) is 1,670 mPa. s, the TI ₂ value is 6.0, TI ₂ /TI ₁ is 0.83, and ηb ₂ /ηb ₁ is 0.82.

<Manufacture of positive electrode precursor>

Using a two-sided extrusion coater manufactured by Toray Engineering Co., Ltd., apply the positive electrode coating solution to both sides of aluminum foil with a thickness of 15 μm at a coating speed of 1 m/s, and adjust the temperature of the drying furnace in sequence It was 50 degreeC, 70 degreeC, 90 degreeC, and 110 degreeC, and it dried afterwards with the IR heater, and the positive electrode precursor 18 was obtained. The obtained positive electrode precursor 18 was pressurized using a roller press under the conditions of a pressure of 6 kN/cm and a surface temperature of the pressurized portion of 25°C. For the full thickness of the positive electrode precursor 18, a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Measuring Instruments Co., Ltd. was used to measure any 10 points of the positive electrode precursor 18. According to the obtained measurement results, the film thickness of each side of the positive electrode active material layer of the positive electrode precursor 1 was 61 μm.

<Measurement of peel strength>

The positive electrode precursor 18 is cut into a width of 25mm and a length of 120mm (100mm is the positive electrode active material layer, the remaining The lower 20 mm is the uncoated portion where the positive electrode active material layer is not coated. ), and cut a 24mm wide transparent tape (registered trademark) (CT405AP-24 made by NICHIBAN) to a length of 100mm and attach it to the positive electrode active material layer. Using TENSILON (STB-1225S manufactured by A&D Co., Ltd.), the uncoated portion of the positive electrode current collector is clamped to the lower jaw (clip jaw) side, and the end of the transparent tape (registered trademark) is clamped to the upper jaw Side and measure the peel strength using the following conditions. After attaching a transparent tape (registered trademark) to the positive electrode active material layer, the peel strength was measured within 3 minutes.

. Ambient temperature: 25℃

. Sample width: 25mm

. Stroke: 100mm

. Speed: 50mm/min

. Obtained data: 25~65mm integral average load

A total of three samples were measured, and the average value was 1.19 N/cm.

<Manufacture of negative electrode>

84 parts by mass of artificial graphite having an average particle diameter of 4.5 μm, 10 parts by mass of acetylene black, and 5 parts by mass of sodium polyacrylate, 1 part by mass of CMC (carboxymethyl cellulose), and distilled water were used to make the mass ratio of the solid content to 39.0 %, and using a film spinning high-speed mixer "FILMIX (registered trademark)" manufactured by PRIMIX, the mixture was dispersed at a peripheral speed of 17 m/s to obtain a negative electrode coating solution.

The viscosity (ηb) and TI value of the obtained negative electrode coating liquid were measured using an E-type viscometer TVE-35H from Toki Industry Co., Ltd. As a result, the viscosity (ηb) was 2,100 mPa. s, TI value is 5.1.

Using an extrusion coating machine manufactured by Toray Engineering Co., Ltd., the negative electrode coating solution was applied to both sides of the electrolytic copper foil with a thickness of 10 μm at a coating speed of 1 m/s, and dried at a drying temperature of 70° C. Negative electrode 7 is obtained. Use a roller press with a pressure of 5kN/cm and a surface temperature of 25℃ Pieces to pressurize. After the pressurization, the entire thickness of the negative electrode 7 was measured at any 10 points of the negative electrode 7 using a film thickness gauge Linear Gauge Sensor GS-551 manufactured by Ono Measuring Instruments Co., Ltd. According to the obtained measurement results, the film thickness of the negative electrode active material layer of the negative electrode 7 was 30 μm per side.

<Preparation of electrolyte>

As an organic solvent, use a mixed solvent of ethyl carbonate (EC): ethyl methyl carbonate (EMC)=33:67 (volume ratio), and dissolve the electrolyte salt so that the concentration of LiFSI and LiBF ₄ is 1:3, and the total concentration is 1.2 mol/L (LiFSI is 0.3 mol/L and LiBF ₄ is 0.9 mol/L) to obtain a non-aqueous electrolyte 16.

<Manufacture of non-aqueous lithium storage elements>

20 pieces of the obtained positive electrode precursor 18 having a size of 10.0 cm×10.0 cm (100 cm ² ) of the positive electrode active material layer were cut out. Next, 21 negative electrodes 7 having a size of 10.1 cm×10.1 cm (102 cm ² ) of negative electrode active material layers were cut out. In addition, 40 pieces of paper-made separators (thickness 20 μm) of 10.3 cm × 10.3 cm (106 cm ² ) were prepared. Regarding these, the negative electrode 7 is arranged in the outermost layer, and the positive electrode active material layer and the negative electrode active material layer are stacked with the separator in the order of the positive electrode precursor 18, the separator, the negative electrode 7, and the separator, thereby The electrode body is obtained. The positive electrode terminal and the negative electrode terminal were ultrasonically welded to the obtained electrode body, and placed in a container formed of an aluminum laminate packaging material, and the three sides including the electrode terminal portion were sealed by heat sealing.

Under a dry air environment at atmospheric pressure, a temperature of 25° C., and a dew point of −40° C. or less, about 75 g of the non-aqueous electrolyte 16 was injected into the electrode body housed in the aluminum laminate packaging material. Next, the aluminum laminate packaging material containing the electrode laminate and the non-aqueous electrolyte solution was placed in a decompression chamber, decompressed from atmospheric pressure to -87 kPa, then returned to atmospheric pressure, and allowed to stand for 5 minutes. Thereafter, the package material in the chamber was repeatedly depressurized from atmospheric pressure to -87 kPa 4 times, and then returned to atmospheric pressure, and then allowed to stand for 15 minutes. Further, after reducing the pressure of the packaging material in the chamber from atmospheric pressure to -91 kPa, it is restored to atmospheric pressure. Repeat the same for the packaging material The steps of depressurization and returning to atmospheric pressure are 7 times in total (from atmospheric pressure, depressurization to -95, -96, -97, -81, -97, -97, -97 kPa). Through the above steps, the non-aqueous electrolyte 16 is impregnated into the electrode laminate.

Thereafter, the aluminum laminate was sealed by putting the electrode laminate impregnated with the non-aqueous electrolyte 16 into a decompression sealer, decompressed to -95 kPa, 180° C., 10 seconds, and a pressure of 0.1 MPa. Packaging materials.

[Alkali metal doping step]

Put the electrode body obtained after sealing into a drying oven with a temperature of 40°C and a dew point of -40°C or lower. The remaining part of the aluminum laminated packaging material is cut and unsealed, and the initial charging is performed by the following method, and the negative electrode is doped with alkali metal: constant current charging at a current value of 500 mA until the voltage is 4.5V, and then the 4.5V setting is continued Charge for 10 hours. After the alkali metal doping is completed, the aluminum laminate is sealed with a heat sealer (FA-300) manufactured by FUJIIMPULSE CO., LTD.

[Aging step]

Take out the electrode body doped with alkali metal from the drying oven, and discharge it at a constant current of 100mA until the voltage is 3.8V at 25°C, then conduct the constant current discharge at 3.8V for 1 hour, and adjust the voltage to 3.8 V. Next, the electrode body was stored in a thermostat at 60°C for 48 hours.

[Exhaust Procedure]

For the electrode body after aging, part of the aluminum laminate packaging material is unsealed in a dry air environment with a temperature of 25°C and a dew point of -40°C. Next, the electrode body was placed in the decompression chamber, and the pressure was reduced from atmospheric pressure to -80 kPa for 3 minutes using a diaphragm pump, and then the procedure of returning to atmospheric pressure in 3 minutes was repeated 3 times. After that, the electrode body was placed in a decompression sealer, reduced to -90 kPa, and then sealed at 200°C, 10 seconds, and a pressure of 0.1 MPa to seal the aluminum laminate packaging material, thereby producing a non-aqueous lithium battery element.

[3.5V micro short circuit check procedure]

According to the above steps, 10 non-aqueous lithium storage elements were fabricated, and the above 3.5V micro-short circuit inspection test was conducted, and the number of micro-short circuits was 0.

<Evaluation of non-aqueous lithium electricity storage device>

[Measurement of discharge capacity Q]

The discharge capacity Q of Example 3-1 was measured at Vmax=4.0V and Vmin=2.2V. For one of the obtained non-aqueous lithium storage elements, use a charge and discharge device (5V, 360A) made by Fujitsu Telecom Fukushima Co., Ltd. (FUJITSU TELECOM NETWORKSFUKUSHIMALIMITED) in a thermostat set at 25°C. Method to determine the electric capacity Q, the electric capacity is 905mAh.

[Determination of internal resistance Ra at room temperature discharge]

The internal resistance Ra of the room temperature discharge of Example 3-1 was measured at Vmax=4.0V and Vmin=2.2V.

For non-aqueous lithium storage elements, use a charge and discharge device (5V, 360A) manufactured by Fujitsu Telecommunications Network Fukushima Co., Ltd. in a thermostat set at 25°C. Calculate the internal resistance Ra by the above method. Ra is 1.15mΩ .

[High Temperature Storage Test 3]

For the non-aqueous lithium storage element, the high-temperature storage test 3 was performed by the above method, and the internal resistance Rb was measured after the test was completed, Rb was 1.66 mΩ, and Rb/Ra=1.44.

<Example 3-2>

In addition to using 43.5 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 5.0 parts by mass of poly Except for sodium acrylate and 1.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-3>

In addition to using 45.0 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 4.0 parts by mass of poly Except for sodium acrylate and 1.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-4>

In addition to using 46.5 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 3.0 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-5>

In addition to using 47.0 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 2.5 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-6>

In addition to using 41.0 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 7.0 parts by mass of poly Except for sodium acrylate and 2.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-7>

In addition to using 40.0 parts by mass of activated carbon 1, 14.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 8.0 parts by mass of poly Except for sodium acrylate and 2.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-8>

In addition to using 40.0 parts by mass of activated carbon 1, 13.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as the lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 9.0 parts by mass of poly Except for sodium acrylate and 2.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-9>

In addition to using 40.0 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 10.0 parts by mass of poly Except for sodium acrylate and 2.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-10>

In addition to using 40.0 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle diameter of 3.5 μm as a lithium transition metal oxide, 31.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 11.0 parts by mass of poly Except for sodium acrylate and 2.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-11>

Except that CMC was not used in the production of the positive electrode coating solution, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1. The produced positive electrode precursor generates cracks on the surface of the positive electrode active material layer.

<Comparative Example 3-1>

In addition to using 38.5 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 31.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 12.0 parts by mass of poly Except for sodium acrylate and 2.5 parts by mass of CMC, non-aqueous lithium electricity storage devices were produced in the same manner as in Example 3-1.

<Comparative Example 3-2>

In addition to using 38.0 parts by mass of activated carbon, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 31.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 12.5 parts by mass of poly Except for sodium acrylate and 2.5 parts by mass of CMC, non-aqueous lithium electricity storage devices were produced in the same manner as in Example 3-1.

<Comparative Example 3-3>

In addition to using 38.0 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 30.5 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 13.0 parts by mass of poly Except for sodium acrylate and 2.5 parts by mass of CMC, non-aqueous lithium electricity storage devices were produced in the same manner as in Example 3-1.

<Comparative Example 3-4>

In addition to using 38.0 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 30.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 13.0 parts by mass of poly Except for sodium acrylate and 3.0 parts by mass of CMC, non-aqueous lithium electricity storage devices were produced in the same manner as in Example 3-1.

<Comparative Example 3-5>

In addition to using 37.5 parts by mass of activated carbon 1, 12.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 30.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 13.5 parts by mass of poly Except for sodium acrylate and 3.0 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Comparative Example 3-6>

In addition to using 47.0 parts by mass of activated carbon 1, 14.5 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 2.0 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Comparative Example 3-7>

In addition to using 47.5 parts by mass of activated carbon 1, 14.5 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 1.5 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Comparative Example 3-8>

In addition to using 48.0 parts by mass of activated carbon 1, 14.5 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 1.0 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Comparative Example 3-9>

In addition to using 48.0 parts by mass of activated carbon 1, 15.0 parts by mass of LiFePO ₄ with an average particle size of 3.5 μm as a lithium transition metal oxide, 32.0 parts by mass of lithium carbonate, 4.0 parts by mass of Ketjen black, and 0.5 parts by mass of poly Except for sodium acrylate and 0.5 parts by mass of CMC, the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Comparative Example 3-10>

Except for using styrene-butadiene rubber instead of sodium polyacrylate as the binder, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

Table 10 shows the results of Examples 3-1 to 3-11 and Comparative Examples 3-1 to 3-10.

According to the above embodiment, when the TI ₂ /TI ₁ is 0.50 or more and 1.20 or less, the peel strength is 0.020 N/cm or more and 3.00 N/cm or less, the micro short-circuit rate can be reduced, and the internal resistance Ra can be reduced. It can be considered that when the peeling strength of the positive electrode active material layer is 0.020 N/cm or more, the peeling of the positive electrode active material layer can be suppressed after lithium doping, and the micro-short-circuit rate decreases. In addition, it can be considered that when the peeling strength of the positive electrode active material layer is 3.00 N/cm or less, since there is no excess binder in the positive electrode active material layer, the diffusibility of the electrolyte is improved and the resistance is reduced. In addition, when sodium polyacrylate is not used as a binder, the resistance increase (Rb/Ra) after the high-temperature storage test becomes larger.

In Example 3-11, CMC was not added to the positive electrode coating solution and the positive electrode precursor. In this case, although TI ₂ /TI ₁ is 0.50 or more and 1.20 or more, but η _b2 / η _{b1 is} greater than 1.3, it is known that it is easy to cause Long-term storage causes viscosity to rise. In addition, in Examples 3-11, since the micro-short circuit rate is also high, the possibility that the cracked positive electrode active material layer slips in the cell and the positive electrode and the negative electrode conduct in some form is taught.

<Example 3-12>

Except that LiNi _0.80 Co _0.15 Al _0.05 O _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-13>

Except that LiNi _0.33 Co _0.33 Mn _0.33 O _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium electricity storage device was produced in the same manner as in Example 3-1.

<Example 3-14>

Except that LiCoO _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium power storage device was fabricated in the same manner as in Example 3-1.

<Example 3-15>

Except that LiMnPO _{4 was used} instead of LiFePO ₄ , the non-aqueous lithium power storage device was fabricated in the same manner as in Example 3-1.

<Example 3-16>

Except that LiMn ₂ O _{4 was used} instead of LiFePO ₄ , non-aqueous lithium electricity storage devices were fabricated in the same manner as in Example 3-1.

<Example 3-17>

Except that Li ₃ V ₂ (PO ₄ ) _{3 was used} instead of LiFePO ₄ , the non-aqueous lithium power storage device was fabricated in the same manner as in Example 3-1.

<Example 3-18>

Except that sodium carbonate was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-19>

Except that potassium carbonate was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-20>

Except that a mixture of sodium carbonate and lithium carbonate in a mass ratio of 1:1 was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-21>

Except that a mixture of potassium carbonate and lithium carbonate in a mass ratio of 1:1 was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-22>

Except that LiFePO _{4 was} not used, non-aqueous lithium electricity storage devices were fabricated in the same manner as in Example 3-1.

<Comparative Example 3-11>

Except that LiNi _0.80 Co _0.15 Al _0.05 O _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium electricity storage device was produced in the same manner as Comparative Example 3-6.

<Comparative Example 3-12>

Except that LiNi _0.33 Co _0.33 Mn _0.33 O _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium power storage device was produced in the same manner as Comparative Example 3-6.

<Comparative Example 3-13>

Except that LiCoO _{2 was used} instead of LiFePO ₄ , the non-aqueous lithium electricity storage device was fabricated in the same manner as Comparative Example 3-6.

<Comparative Example 3-14>

Except that LiMnPO _{4 was used} instead of LiFePO ₄ , the non-aqueous lithium electricity storage device was produced in the same manner as Comparative Example 3-6.

<Comparative Example 3-15>

Except that LiMn ₂ O _{4 was used} instead of LiFePO ₄ , non-aqueous lithium electricity storage devices were produced in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-16>

Except that Li ₃ V ₂ (PO ₄ ) _{3 was used} instead of LiFePO ₄ , the non-aqueous lithium power storage device was produced in the same manner as Comparative Example 3-6.

<Comparative Example 3-17>

Except for using sodium carbonate instead of lithium carbonate, all others were prepared in the same way as Comparative Example 3-6 Used as a non-aqueous lithium storage element.

<Comparative Example 3-18>

Except that potassium carbonate was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as Comparative Example 3-6.

<Comparative Example 3-19>

Except that a mixture of sodium carbonate and lithium carbonate in a mass ratio of 1:1 was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-20>

Except that a mixture of potassium carbonate and lithium carbonate in a mass ratio of 1:1 was used instead of lithium carbonate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-21>

Except that LiFePO _{4 was} not used, non-aqueous lithium electricity storage devices were produced in the same manner as in Comparative Examples 3-6.

The evaluation results of Examples 3-12 to 3-22 and Comparative Examples 3-11 to 3-21 are shown in Table 11.

From Table 11, it can be confirmed that even when the lithium transition metal oxide is changed or the alkali metal carbonate is changed, the peel strength can be made to be 0.020 N/ when the TI ₂ /TI ₁ is 0.50 or more and 1.20 or less. A positive electrode precursor of cm or more and 3.00 N/cm or less, and a non-aqueous lithium storage element with a low micro-short-circuit rate and a small increase in resistance under high-temperature storage tests can be produced.

<Example 3-23>

The positive electrode precursor 18 is cut to a size of 12.0 cm×210.0 cm (the size of the positive electrode active material layer is 10.0 cm×210.0 cm, and the positive electrode uncoated portion on which the positive electrode active material layer is not coated is 2.0 cm×210.0cm.), and cut the negative electrode 7 to a size of 12.1×220.0cm (the size of the negative electrode active material layer is 10.1cm×220.0cm, and the negative electrode is not coated with the negative electrode active material layer. The coated portion is 2.0 cm×220.0 cm.), and the cut positive electrode precursor and negative electrode are wound through a separator (thickness 20 μm) made of paper to produce a wound electrode body.

The terminal was connected to the obtained electrode wound body, and inserted into a square metal can made of aluminum to seal. The non-aqueous electrolyte 16 is injected through the opening of the aforementioned metal square tank, and thereafter, a detachable check valve is installed. Place the resulting device in a drying oven at a temperature of 40°C and a dew point of -40°C or less, pressurize it with a pressure of 100kPa, and charge it at a constant current with a current value of 500mA until the voltage is 4.5V, and then continue to conduct 4.5V The method of constant voltage charging for 10 hours is used for initial charging, and the negative electrode is doped with alkali metal. Next, the aging was performed under the same conditions as in Example 3-1, and after removing the check valve, the exhaust was performed under the same conditions as in Example 3-1, and the opening of the element was sealed.

Evaluation was carried out in the same manner as in Example 3-1, with a micro short-circuit rate of 0%, a capacitance Q=910 mAh, an internal resistance Ra=1.18 mΩ, an internal resistance Rb=1.71 mΩ, and Rb/Ra=1.45 after the high-temperature storage test.

<Example 3-24>

In addition to the use of acrylic acid/maleic acid copolymer sodium salt instead of sodium polyacrylate, all other In the same manner as in Example 3-1, a non-aqueous lithium electricity storage element was produced.

<Example 3-25>

Except that the sodium salt of acrylic acid/ethylenesulfonic acid copolymer was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-26>

Except that the sodium salt of acrylic acid/methacrylic acid copolymer was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-27>

Except for using polymethyl acrylate instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Example 3-28>

Except that polyacrylic acid was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Example 3-1.

<Comparative Example 3-22>

Except that the sodium salt of acrylic acid/maleic acid copolymer was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was produced in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-23>

Except that the sodium salt of acrylic acid/ethylenesulfonic acid copolymer was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-24>

Except that the sodium salt of acrylic acid/methacrylic acid copolymer was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was produced in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-25>

Except for using polymethyl acrylate instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was produced in the same manner as in Comparative Examples 3-6.

<Comparative Example 3-26>

Except that polyacrylic acid was used instead of sodium polyacrylate, the non-aqueous lithium electricity storage device was fabricated in the same manner as Comparative Example 3-6.

The evaluation results of Examples 3-24 to 3-28 and Comparative Examples 3-22 to 3-26 are shown in Table 12.

【Industrial Utilization】

The non-aqueous lithium electricity storage element of the present invention can be suitably used as an electricity storage element for auxiliary use of an instantaneous power peak in a hybrid drive system of an automobile, for example.

The non-aqueous lithium electricity storage device of the present invention is preferably used, for example, when it is applied as a lithium-ion capacitor or a lithium-ion secondary battery to maximize the effect of the present invention.

Claims (6)

A non-aqueous lithium electricity storage element comprising: a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte; characterized in that the positive electrode has a positive electrode current collector, and is disposed on one or both sides of the positive electrode current collector Positive electrode active material layer; the positive electrode active material layer contains a positive electrode active material, a lithium compound other than the positive electrode active material, and a binder; the binder contains a polymer based on the non-aqueous electrolysis The RED value of the Hansen solubility parameter of the liquid is greater than 1; the negative electrode has a negative electrode collector and a negative electrode active material layer disposed on one or both sides of the negative electrode collector; the negative electrode active material layer contains A negative electrode active material that absorbs and releases lithium ions; the withstand voltage of the separator is 0.8 kV or more; and the separator has a length of the separator after setting the length of the original separator to L1 and keeping it at 120°C for 1 hour When set to L2, the shrinkage ratio calculated from (L1-L2)/L1 is 0.1 or less; the non-aqueous electrolyte solution includes an organic solvent and a lithium salt electrolyte; voltage) 4.1V and the initial internal resistance at an ambient temperature of 25°C is set to Ra (Ω). After storing the unit voltage at 4.1V and an ambient temperature of 85°C for 1000 hours, the internal resistance at a unit voltage of 4.1V and an ambient temperature of 25°C When it is set to Rb (Ω), Rb/Ra is 3.0 or less. An electric storage module, characterized in that it includes a non-aqueous lithium electric storage element as described in item 1 of the patent application scope. An electricity storage system characterized by connecting a non-aqueous lithium electricity storage element as described in item 1 of the patent application series and a lead battery, a nickel-hydrogen battery, a lithium ion secondary battery or a fuel cell in series or parallel. An electric vehicle is characterized by including a non-aqueous lithium storage element as described in item 1 of the patent application. A hybrid vehicle characterized by including a non-aqueous lithium power storage element as described in item 1 of the patent application. An electric locomotive is characterized by including a non-aqueous lithium electricity storage element as described in item 1 of the patent scope.