JP6912337B2 - Non-aqueous lithium storage element - Google Patents

Description

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

In recent years, from the viewpoint of effective use of energy aiming at conservation of the global environment and resource saving, power smoothing system or midnight power storage system for wind power generation, distributed power storage system for home use based on solar power generation technology, power storage for electric vehicles Systems and the like are attracting attention.

The first requirement of the batteries used in these power storage systems is high energy density. Lithium-ion batteries are being energetically developed as promising candidates for high-energy density batteries that can meet such demands.

The second requirement is high output characteristics. For example, in a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle), a power storage system that exhibits high output discharge characteristics during acceleration is required. Has been done.

Currently, electric double layer capacitors, nickel-metal hydride batteries, and the like are being developed as high-power power storage devices.

Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has not only high output characteristics but also high durability (cycle characteristics and high temperature storage characteristics), and has been considered to be the most suitable device in the above-mentioned field where high output is required. However, its energy density is only about 1 to 5 Wh / L. Therefore, it is necessary to further improve the energy density.

On the other hand, the nickel-metal hydride battery generally used in hybrid electric vehicles at present has a high output equivalent to that of an electric double layer capacitor and an energy density of about 160 Wh / L. However, research is being vigorously pursued to further enhance its energy density and output characteristics and to enhance its durability (particularly, stability at high temperatures).

In addition, research is underway to increase the output of lithium-ion batteries. For example, a lithium ion battery has been developed in which a high output exceeding 3 kW / L can be obtained at a discharge depth (that is, a ratio (%) of the amount of discharge to the discharge capacity of the power storage element) of 50%. However, its energy density is 100 Wh / L or less, and the design intentionally suppresses the high energy density, which is the greatest feature of lithium-ion batteries. Moreover, its durability (cycle characteristics and high temperature storage characteristics) is inferior to that of electric double layer capacitors. Therefore, such lithium-ion batteries are used in a range where the discharge depth is narrower than the range of 0 to 100% in order to have practical durability. Since the capacity that can be actually used becomes smaller, research for further improving durability is being energetically pursued.

As described above, there is a strong demand for practical application of a power storage element having high energy density, high output characteristics, and high durability. However, each of the existing power storage elements described above has advantages and disadvantages. Therefore, there is a demand for a new power storage element that satisfies these technical requirements. As a promising candidate, a power storage element called a lithium ion capacitor has attracted attention and is being actively developed.

A lithium ion capacitor is a kind of storage element (hereinafter, also referred to as "non-aqueous lithium storage element") that uses a non-aqueous electrolyte solution containing a lithium salt, and is an electric double layer capacitor at about 3 V or more at a positive electrode. It is a power storage element that charges and discharges by a non-Faraday reaction by adsorption and desorption of anions, and a Faraday reaction by storage and release of lithium ions at the negative electrode, which is similar to that of a lithium ion battery.

To summarize the electrode materials generally used for the above-mentioned energy storage element and their characteristics, generally, a material such as activated carbon is used for the electrode, and charging / discharging is performed by adsorption and desorption (non-Faraday reaction) of ions on the surface of activated carbon. When this is done, high output and high durability are obtained, but the energy density is low (for example, 1 times). On the other hand, when an oxide or carbon material is used for the electrode and charging / discharging is performed by the Faraday reaction, the energy density becomes high (for example, 10 times that of the non-Faraday reaction using activated carbon), but the durability and output are increased. There is a problem with the characteristics.

As a combination of these electrode materials, the electric double layer capacitor is characterized in that activated carbon (energy density 1 times) is used for the positive electrode and the negative electrode, and both the positive electrode and the negative electrode are charged and discharged by a non-Faraday reaction, and therefore high output and high durability. Although it has properties, it is characterized by low energy density (1x positive electrode x 1x negative electrode = 1).

The lithium ion secondary battery is characterized by using a lithium transition metal oxide (energy density 10 times) for the positive electrode and a carbon material (energy density 10 times) for the negative electrode, and charging and discharging both the positive electrode and the negative electrode by a Faraday reaction. It has a high energy density (10 times positive electrode x 10 times negative electrode = 100), but has problems in output characteristics and durability. Further, in order to satisfy the high durability required for a hybrid electric vehicle or the like, the discharge depth must be limited, and the lithium ion secondary battery can use only 10 to 50% of its energy.

Lithium-ion capacitors are characterized by using activated carbon (1x energy density) for the positive electrode and carbon material (10x energy density) for the negative electrode, and charging and discharging by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode. It is an asymmetric capacitor that combines the characteristics of an electric double-layer capacitor and a lithium-ion secondary battery. The lithium-ion capacitor has a high energy density (1x positive electrode x 10x negative electrode = 10) while having high output and high durability, and it is not necessary to limit the discharge depth unlike a lithium ion secondary battery. Is a feature.

Various studies have been conducted on the positive electrode of the power storage element (particularly the lithium ion secondary battery) described above.
For example, Patent Document 1 proposes a lithium ion secondary battery that uses a positive electrode containing lithium carbonate in the positive electrode and has a current cutoff mechanism that operates in response to an increase in battery internal pressure. Patent Document 2 proposes a lithium ion secondary battery in which a lithium composite oxide such as a lithium manganese oxide is used as a positive electrode and lithium carbonate is contained in the positive electrode to suppress elution of manganese. Patent Document 3 proposes a method of oxidizing various lithium compounds as oxides at a positive electrode to recover the capacity of a deteriorated power storage element.

However, the positive electrodes described in Patent Documents 1 to 3 still have room for improvement in application to asymmetric capacitors such as lithium ion capacitors, and the lithium compound in the positive electrode is particularly used in a high load charge / discharge cycle of a non-aqueous lithium storage element. No studies have been made on suppressing the decomposition of lithium-ion capacitors and suppressing gas generation and resistance increase.

Japanese Unexamined Patent Publication No. 7-328278 Japanese Unexamined Patent Publication No. 2001-167767 Japanese Unexamined Patent Publication No. 2012-174437

The present invention has been made in view of the above situation.
Therefore, the problem to be solved by the present invention is that in a non-aqueous lithium power storage element containing an alkali metal compound such as a lithium compound in the positive electrode, the resistance changes when the temperature at the center of the power storage element rises due to a high load charge / discharge cycle. Is reduced, and gas generation is suppressed by suppressing the decomposition of the alkali metal compound in the positive electrode.
The present invention has been made based on this finding.

The above problem is solved by the following technical means.
That is, the present invention is as follows:
[1]
Positive electrode containing alkali metal compounds other than active material,
Negative electrode,
Separator, and non-aqueous electrolyte solution containing lithium ions,
It is a non-aqueous lithium storage element containing
A positive electrode active material layer composed of the active material and the alkali metal compound is coated on the positive electrode current collector of the positive electrode, and the amount of the alkali metal compound in the central portion of the positive electrode active material layer is C _{x 1} (g / m). The ratio C _x1 / _{Cy1 of} ² ) and the amount of alkali metal compound _Cy1 (g / m ² ) on the outer peripheral portion is 0.50 or more and 0.96 or less.
The non-aqueous lithium storage element.
[2]
Wherein the ratio _C x2 _{/ C y2} of the active material of the central portion of the positive electrode active material layer _C x2 (g / ^{m 2)} and the active material amount of the outer peripheral portion _C y2 (g / ^{m 2)} is 0.85 or more The non-aqueous lithium storage element according to [1], which is 1.15 or less.
[3]
In the element mapping obtained by scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX) on the surface of the positive electrode, the area overlap rate A of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness. The non-aqueous lithium storage element according to [1] or [2], wherein _{1 is 40% or more and 99% or less.}
[4]
In the element mapping obtained by SEM-EDX of the cross section of the positive electrode processed by broad ion beam (BIB), the area overlap rate A ₂ of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is 10%. The non-aqueous lithium storage element according to any one of [1] to [3], which is 60% or less.
[5]
The non-aqueous lithium power storage element according to any one of [1] to [4], wherein the alkali metal compound is lithium carbonate, lithium oxide, or lithium hydroxide.
[6]
The positive electrode active material layer is provided on one side or both sides of the positive electrode current collector.
The amount of mesopores derived from the pores of the positive electrode active material contained in the positive electrode active material layer 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 diameter is less than 20 Å calculated by the MP method. When the amount of micropores derived from the pores is V ₂ (cc / g), 0.3 <V ₁ ≤ 0.8 and 0.5 ≤ V ₂ ≤ 1.0 are satisfied, and the BET method is used. Activated carbon having a measured specific surface area of 1,500 m ² / g or more and 3,000 m ² / g or less.
The non-aqueous lithium storage element according to any one of [1] to [5].
[7]
_{The positive electrode active material contained in the positive electrode active material layer has a mesopore amount V 1} (cc / g) of 0.8 <V ₁ ≤ 2.5 derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method. _{, And the micropore amount V 2} (cc / g) derived from pores with a diameter of less than 20 Å calculated by the MP method satisfies _{0.8 <V 2} ≤ 3.0, and the ratio measured by the BET method. The non-aqueous lithium storage element according to any one of [1] to [5], which is an activated carbon having a surface area of 2,300 m ² / g or more and 4,000 m ^{2 / g or less.}
[8]
Item 2. The non-aqueous lithium storage element described.
[9]
The non-aqueous lithium storage element according to [8], wherein the negative electrode active material has a BET specific surface area of 100 m ² / g or more and 1,500 m ^{2 / g or less.}
[10]
The item according to any one of [1] to [7], wherein the doping amount of lithium ion with respect to the negative electrode active material contained in the negative electrode is 50 mAh / g or more and 700 mAh / g or less per unit mass of the negative electrode active material. Non-aqueous lithium storage element.
[11]
The non-aqueous lithium storage element according to [10], wherein the BET specific surface area of the negative electrode active material is 1 m ² / g or more and 50 m ^{2 / g or less.}
[12]
The non-aqueous lithium storage element according to any one of [8] to [11], wherein the average particle size of the negative electrode active material is 1 μm or more and 10 μm or less.
[13]
A power storage module including the non-aqueous lithium power storage element according to any one of [1] to [12].
[14]
A power regeneration assist system including the non-aqueous lithium storage element according to any one of [1] to [12].
[15]
A power load leveling system including the non-aqueous lithium storage element according to any one of [1] to [12].
[16]
An uninterruptible power supply system including the non-aqueous lithium storage element according to any one of [1] to [12].
[17]
A non-contact power supply system including the non-aqueous lithium storage element according to any one of [1] to [12].
[18]
An energy harvesting system including the non-aqueous lithium storage element according to any one of [1] to [12].
[19]
A power storage system including the non-aqueous lithium power storage element according to any one of [1] to [12].
[20]
A power storage system in which the non-aqueous lithium power storage element according to any one of [1] to [12] and a lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell are connected in series or in parallel.
[21]
A photovoltaic power generation power storage system including the non-aqueous lithium power storage element according to any one of [1] to [12].
[22]
An electric power steering system including the non-aqueous lithium storage element according to any one of [1] to [12].
[23]
An emergency power supply system including the non-aqueous lithium storage element according to any one of [1] to [12].
[24]
An in-wheel motor system including the non-aqueous lithium storage element according to any one of [1] to [12].
[25]
An idling stop system including the non-aqueous lithium storage element according to any one of [1] to [12].
[26]
A vehicle including the non-aqueous lithium storage element according to any one of [1] to [12].
[27]
The vehicle according to [26], which is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric motorcycle.
[28]
A quick charging system including the non-aqueous lithium storage element according to any one of [1] to [12].
[29]
A smart grid system including the non-aqueous lithium storage element according to any one of [1] to [12].

According to the present invention, when the temperature of the central portion of the non-aqueous lithium storage element rises due to the high load charge / discharge cycle, the resistance change is small, the excessive decomposition of the alkali metal compound contained in the positive electrode is suppressed, and the gas is suppressed. It is possible to provide a non-aqueous lithium storage element with less generation.

FIG. 1 is a top view of a positive electrode active material layer for explaining a central portion and an outer peripheral portion of the positive electrode active material layer according to the embodiment of the present invention including a laminated body of single-wafer electrodes. FIG. 2 is a projection drawing of the positive electrode active material layer for explaining the central portion and the outer peripheral portion of the positive electrode active material layer according to another embodiment of the present invention in which the electrode laminate is wound. FIG. 3 is a schematic cross-sectional view of a non-aqueous lithium storage element including the electrode wound laminate cut out as shown in FIG. 2 in the plane direction.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the present embodiment. The upper limit value and the lower limit value in each numerical range of the present embodiment can be arbitrarily combined to form an arbitrary numerical range.

A non-aqueous lithium storage element generally includes a positive electrode, a negative electrode, a separator, and an electrolytic solution as main components. As the electrolytic solution, an organic solvent containing lithium ions (hereinafter, also referred to as “non-aqueous electrolytic solution”) is used.

<Positive electrode>
The positive electrode in the present embodiment has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material provided on one or both sides of the current collector.

The positive electrode in the present embodiment preferably contains an alkali metal compound as a positive electrode precursor before assembling the power storage element. As will be described later, in the present embodiment, it is preferable to pre-dope the negative electrode with lithium ions in the step of assembling the power storage element. As a predoping method in the present embodiment, after assembling a power storage element using a positive electrode precursor containing a lithium compound, a negative electrode, a separator, and a non-aqueous electrolyte solution, a voltage is applied between the positive electrode precursor and the negative electrode. It is preferable to apply. The alkali metal compound is preferably contained in the positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor.

In the present specification, the positive electrode before the lithium doping process is defined as a “positive electrode precursor”, and the positive electrode after the lithium doping process is defined as a “positive electrode”.

[Cathode active material layer]
The positive electrode active material layer contains a positive electrode active material, and may also contain optional components such as a conductive filler, a binder, and a dispersion stabilizer, if necessary. The positive electrode active material preferably contains a carbon material.
The positive electrode active material layer of the positive electrode precursor preferably contains an alkali metal compound such as a lithium compound.

[Positive electrode active material]
The positive electrode active material is a substance involved in a Faraday reaction or a non-Faraday reaction during charging and discharging of the power storage element, and preferably contains a carbon material. Examples of the carbon material include carbon nanotubes, a conductive polymer, and a porous carbon material, and more preferably activated carbon. The positive electrode active material may contain a mixture of two or more kinds of materials, and may contain a material other than the carbon material, for example, a composite oxide of lithium and a transition metal.

The content of the carbon material with respect to the total mass of the positive electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material may be 100% by mass, but from the viewpoint of obtaining a good effect when used in combination with other materials, for example, it is preferably 90% by mass or less, even if it is 80% by mass or less. good.

When activated carbon is used as the positive electrode active material, the type of activated carbon and its raw material are not particularly limited. However, in order to achieve both high input / output characteristics and high energy density, it is preferable to optimally control the pores of the activated carbon. Specifically, the amount of mesopores 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 amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When is V ₂ (cc / g),
(1) In order to obtain high input / output characteristics, 0.3 <V ₁ ≤ 0.8 and 0.5 ≤ V ₂ ≤ 1.0 are satisfied, and the specific surface area measured by the BET method is 1. , 500 m ² / g or more and 3,000 m ² / g or less of activated carbon (hereinafter, also referred to as “activated carbon 1”) is preferable.
(2) In order to obtain a high energy density, 0.8 <V ₁ ≤ 2.5 and 0.8 <V ₂ ≤ 3.0 are satisfied, and the specific surface area measured by the BET method is 2, Activated carbon having a thickness of 300 m ² / g or more and 4,000 m ² / g or less (hereinafter, also referred to as “activated carbon 2”) is preferable.
Hereinafter, (1) activated carbon 1 and (2) activated carbon 2 will be described individually in sequence.

(Activated carbon 1)
Meso Anaryou V ₁ of the activated carbon 1, in terms of increasing the output characteristics when incorporating the positive electrode material in the capacitor is preferably 0.3 cc / g greater than. _{On the other hand, the V 1} of the activated carbon 1 is preferably 0.8 cc / g or less from the viewpoint of suppressing a decrease in the bulk density of the positive electrode. _{The V 1} of the activated carbon 1 is more preferably 0.35 cc / g or more and 0.7 cc / g or less, and further preferably 0.4 cc / g or more and 0.6 cc / g or less.

The micropore amount V ₂ of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area and the capacity of the activated carbon. _{On the other hand, the V 2} of the activated carbon 1 is preferably 1.0 cc / g or less from the viewpoint of suppressing the bulk of the activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume. _{The V 2} of the activated carbon 1 is more preferably 0.6 cc / g or more and 1.0 cc / g or less, and further preferably 0.8 cc / g or more and 1.0 cc / g or less.

The ratio of meso Anaryou _{V 1} relative to the micropore volume _{V 2} of activated carbon 1 _(V 1 / V ₂₎ is preferably in the range of _{0.3 ≦ V 1 / V 2 ≦} 0.9. That is, from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to the extent that the decrease in output characteristics can be suppressed while maintaining a high capacity, V ₁ / V ₂ of the activated carbon 1 is 0.3 or more. It is preferable to have. _{On the other hand, V 1} / V ₂ of activated carbon 1 is 0.9 or less from the viewpoint of increasing the ratio of the amount of micropores to the amount of mesopores to the extent that the decrease in capacity can be suppressed while maintaining high output characteristics. Is preferable. _{The range of V 1} / V ₂ of the activated carbon 1 is more preferably 0.4 ≤ V ₁ / V ₂ ≤ 0.7, _{and even more preferably 0.55 ≤ V 1} / V ₂ ≤ 0.7.

The average pore diameter of the activated carbon 1 is preferably 17 Å or more, more preferably 18 Å or more, and even more preferably 20 Å or more, from the viewpoint of increasing the output of the obtained power storage element. Further, from the viewpoint of increasing the capacity, the average pore diameter of the activated carbon 1 is preferably 25 Å or less.

BET specific surface area of the activated carbon 1 is preferably from 1,500 m ² / g or more 3,000 m ² / g, more preferably not more than 1,500 m ² / g or more 2,500 m ² / g. When the BET specific surface area of the activated carbon 1 is 1,500 m ² / g or more, a good energy density can be easily obtained, while when the BET specific surface area of the activated carbon 1 is 3,000 m ² / g or less, the electrode Since it is not necessary to add a large amount of binder in order to maintain the strength of the electrode, the performance per electrode volume is improved.

Activated carbon 1 having the above characteristics can be obtained, for example, by using the raw materials and the treatment method described below.

In the present embodiment, the carbon source used as the raw material of the activated carbon 1 is not particularly limited. Examples of the carbon source of the activated charcoal 1 include wood, wood flour, coconut shells, by-products during pulp production, bagas, plant-based raw materials such as waste sugar honey; Fossil raw materials such as pitch, coke, and coal tar; various synthetic resins such as phenol resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, and polyamide resin. ; Synthetic rubbers such as polybutylene, polybutadiene, polychloroprene; other synthetic woods, synthetic pulps, etc., and carbonized products thereof. Among these raw materials, plant-based raw materials such as coconut shells and wood flour and their carbides are preferable, and coconut shell carbides are particularly preferable, from the viewpoint of mass production and cost.

As a carbonization and activation method for producing activated carbon 1 from these raw materials, known 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 adopted.

As a method for activating the carbide obtained by the above carbonization method, a gas activation method in which the carbide is fired using an activation gas such as steam, carbon dioxide, or oxygen is preferably used. A method using water vapor or carbon dioxide as the activating gas is more preferable.

In this activation method, the carbide is supplied for 3 to 12 hours, preferably 5 to 11 hours while supplying the activation gas at a ratio of 0.5 to 3.0 kg / h, preferably 0.7 to 2.0 kg / h. More preferably, the temperature is raised to 800 to 1,000 ° C. over 6 to 10 hours for activation.

Further, the carbide may be first activated in advance prior to the activation treatment of the carbide. In this primary activation, it is usually preferable to fire a carbon material at a temperature of less than 900 ° C. to activate the gas using an activation gas such as steam, carbon dioxide, or oxygen.

Activated carbon 1 having the above characteristics, which is preferable in the present embodiment, can be produced by appropriately combining the firing temperature and firing time in the carbonization method with the amount of activated gas supplied, the rate of temperature rise, and the maximum activation temperature in the activation method. can.

The average particle size of the activated carbon 1 is preferably 2 to 20 μm. When the average particle size of the activated carbon 1 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 of the activated carbon 1 is small, the durability may be low, but if the average particle size is 2 μm or more, the durability is unlikely to be low. When the average particle size of the activated carbon 1 is 20 μm or less, it tends to be easily adapted to high-speed charging / discharging. The average particle size of the activated carbon 1 is more preferably 2 to 15 μm, still more preferably 3 to 10 μm.

(Activated carbon 2)
Meso Anaryou V ₁ of the activated carbon 2, from the viewpoint of increasing the output characteristics when incorporating the positive electrode material in the capacitor is preferably 0.8 cc / g greater than, on the one hand, the capacity of the power storage element From the viewpoint of suppressing the decrease, it is preferably 2.5 cc / g or less. _{The V 1} of the activated carbon 2 is more preferably 1.00 cc / g or more and 2.0 cc / g or less, and further preferably 1.2 cc / g or more and 1.8 cc / g or less.

The micropore amount V ₂ of the activated carbon 2 is preferably a value larger than 0.8 cc / g in order to increase the specific surface area and the capacity of the activated carbon. From the viewpoint of increasing the density of the activated carbon as an electrode and increasing the capacity per unit volume, the V ₂ of the activated carbon 2 is preferably 3.0 cc / g or less. _{The V 2} of the activated carbon 2 is more preferably larger than 1.0 cc / g and 2.5 cc / g or less, and further preferably 1.5 cc / g or more and 2.5 cc / g or less.

The activated carbon 2 having the above-mentioned meso-pore amount and micro-pore amount has a higher BET specific surface area than the activated carbon used for conventional electric double layer capacitors or lithium ion capacitors. 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, and 3,000 m ² / g or more and 4,000 m ² / g or less. It is more preferable, and it is more preferable that it is 3,200 m ² / g or more and 3,800 m ² / g or less. When the BET specific surface area of the activated carbon 2 is 2,300 m ² / g or more, a good energy density can be easily obtained, and when the BET specific surface area of the activated carbon 2 is 4,000 m ² / g or less, the strength of the electrode. Since it is not necessary to add a large amount of binder in order to maintain the temperature, the performance per electrode volume is improved.

Activated carbon 2 having the above characteristics can be obtained by using, for example, the raw materials and treatment methods described below.

The carbonaceous material used as a raw material for the activated charcoal 2 is not particularly limited as long as it is a carbon source usually used as a raw material for activated charcoal. Fossil raw materials such as coke; various synthetic resins such as phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin and the like can be mentioned. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon 2 having a high specific surface area.

Examples of the method of carbonizing these raw materials or the heating method at the time of activation treatment include known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. As the atmosphere at the time of heating, an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas containing these inert gases as a main component and mixed with other gases is used. Generally, the carbonization temperature is about 400 to 700 ° C. and the carbonization time is about 0.5 to 10 hours.

Examples of the method for activating the carbide after the carbonization treatment include a gas activation method in which the carbide is fired using an activation gas such as water vapor, carbon dioxide, and oxygen, and an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound. An alkali metal activation method is preferable for producing activated carbon having a high specific surface area.

In this activation method, the mass ratio of carbides to alkali metal hydroxides such as KOH and NaOH is 1: 1 or more (the amount of alkali metal hydroxide is equal to or greater than the amount of carbides). After mixing so as to be, heating is carried out in the range of 600 to 900 ° C. for 0.5 to 5 hours in an inert gas atmosphere, and then the alkali metal compound is washed and removed with acid and water, and further dried. preferable.

In order to increase the amount of micropores and not increase the amount of mesopores, it is advisable to increase the amount of carbides at the time of activation and mix with KOH. In order to increase both the amount of micropores and the amount of mesopores, it is advisable to use a large amount of KOH. Further, in order to mainly increase the amount of mesopores, it is preferable to perform steam activation after performing 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.

(Usage mode of activated carbon)
Activated carbons 1 and 2 may be a single activated carbon, respectively, or may be a mixture of two or more types of activated carbon, and the mixture as a whole may exhibit the above-mentioned characteristics.

As the activated carbons 1 and 2, either one of these may be selected and used, or both may be mixed and used.

The positive electrode active material is a material other than activated carbon 1 and 2, for example, _{activated carbon that does not have the specific V 1} and / or V ₂ , or a material other than activated carbon, for example, a composite oxide of lithium and a transition metal. It may be included. In an exemplary embodiment, the content of activated carbon 1, the content of activated carbon 2, or the total content of activated carbons 1 and 2 is preferably more than 50% by mass, respectively, and 70% by mass or more of the total positive electrode active material. More preferably, 90% by mass or more is further preferable, and 100% by mass is even more preferable.

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 in 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, further preferably 55% by mass or more. On the other hand, the upper limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, and further preferably 85% by mass or less. By setting the content ratio of the positive electrode active material in this range, suitable charge / discharge characteristics are exhibited.

(Alkali metal compound)
Alkali metal compounds are compounds containing metals from the second period onward in Group 1 of the Periodic Table of the Elemental Period and other elements. The alkali metal compound is, for example, a salt, hydroxide, oxide, nitride, carbide or halide of an alkali metal such as Li, Na, K, Rb, Cs, or an alkali metal and an alkaline earth metal or It may be a composite oxide with a transition metal.
However, in the present specification, the term "alkali metal compound" refers to an active material (for example, a lithium-transition metal composite oxide as a positive electrode active material) involved in a faraday reaction or a non-faraday reaction in an electrode during charging / discharging of a power storage element. , Alkali metal hydroxide contained in the active material by activation treatment), and lithium salt contained in the non-aqueous electrolyte solution (for example, LiPF ₆ or LiN (SO ₂ F) ₂ contained in the non-aqueous electrolyte solution) are excluded. And.
Examples of the alkali metal compound include lithium compounds, sodium compounds, potassium compounds, cesium compounds and the like.
The lithium compound in the present embodiment is one selected from lithium carbonate, lithium oxide, lithium hydroxide, lithium fluoride, lithium chloride, lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and lithium acetate. The above is preferably used. Among them, lithium carbonate, lithium oxide, and lithium hydroxide are more preferable, and lithium carbonate is more preferably used from the viewpoint that it can be handled in the air and has low hygroscopicity. Such a lithium compound decomposes when a voltage is applied, functions as a dopant source for lithium doping to the negative electrode, and forms pores in the positive electrode active material layer. Therefore, the electrolyte solution is excellent in retention and ionic conductivity. It is possible to form an excellent positive electrode. In addition to the lithium compound, one or more alkali metal carbonates selected from sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate can also be used. _{When an electrolytic solution in which a lithium salt such as LiPF 6} described later is dissolved in advance is used as the non-aqueous electrolytic solution, the alkali metal carbonate can also be used alone. The lithium compound contained in the positive electrode precursor may be one kind, may contain two or more kinds of lithium compounds, and may be used by mixing the lithium compound with another alkali metal carbonate.
Further, the positive electrode precursor of the present embodiment may contain at least one lithium compound, and in addition to the lithium compound, M in the following formula may be one or more selected from Na, K, Rb and Cs. ,
Oxides such as M ₂ O,
Hydroxides such as MOH,
Halides such as MF and MCl,
Oxalates such as M ₂ (CO ₂ ) ₂ and carboxylic acid salts such as RCOM (R is H, alkyl group, aryl group),
May be contained in one or more kinds.
Also, the positive electrode _{precursor, BeCO 3, MgCO 3, CaCO} 3, SrCO 3, alkaline earth metal carbonate selected from BaCO _3, as well as alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth It may contain one or more metal halides, alkaline earth metal oxalates, and alkaline earth metal carboxylates.

The positive electrode precursor according to the present embodiment can contain fine particles of an alkali metal compound such as a lithium compound. Various methods can be used for atomizing the alkali metal compound. For example, a crusher such as a ball mill, a bead mill, a ring mill, a jet mill, or a rod mill can be used.

Regarding the positive electrode according to the present embodiment, the amount of the alkali metal compound contained in the central portion of the positive electrode active material layer is C _{x 1} (g / m ² ), and the amount of the alkali metal compound contained in the outer peripheral portion of the positive electrode active material layer is C. _{When y1} (g / m ² ), C _x1 and _Cy1 are preferably 0.1 or more and 20 or less, respectively, and C _x1 / _Cy1 is preferably 0.50 or more and 0.96 or less. When C _x1 and _Cy1 are 0.1 or more, respectively, fluorine ions generated in the high load charge / discharge cycle can be captured, so that the resistance increase can be suppressed. When C _x1 and _Cy1 are 20 or less, the output characteristics are improved because the diffusion of the electrolytic solution and ions contained in the positive electrode is improved.

When a high-load charge / discharge cycle is performed on a non-aqueous lithium power storage element, heat is generated in proportion to the square of the charge / discharge current value (assuming that the calorific value is J, the current value is I, and the resistance of the power storage element is R, J = I. ² R) However, since heat is dissipated mainly from the terminal portion and the outer peripheral portion of the power storage element, the temperature in the central portion rises. At this time, by lowering the amount of the alkali metal compound contained in the central portion of the positive electrode active material layer from that of the outer peripheral portion, excessive decomposition of the alkali metal compound can be suppressed. When C _x1 / _Cy1 is 0.50 or more, it is possible to suppress an increase in resistance in a high load charge / discharge cycle. When C _x1 / _Cy1 is 0.96 or less, excessive decomposition of the alkali metal compound in the central portion of the positive electrode active material layer can be suppressed, and gas generation can be reduced.

On the other hand, for the positive electrode according to the present embodiment, the amount of active material contained in the central portion of the positive electrode active material layer is C _{x 2} (g / m ² ), and the amount of active material contained in the outer peripheral portion of the positive electrode active material layer. When C _y2 (g / m ² ), the ratio C _x2 / _{Cy2 of the} two is preferably 0.85 or more and 1.15 or less. In this embodiment, the ratio C _x2 / _Cy2 contradicts the ratio C _x1 / _Cy1. Therefore, when the ratio C _x2 / _Cy2 is 0.85 or more, excessive decomposition of the alkali metal compound can be suppressed by suppressing the potential rise in the central portion of the positive electrode active material layer, and gas generation is reduced. be able to. Further, when the ratio C _x2 / _Cy2 is 1.15 or less, the diffusion of ions in the central portion of the positive electrode active material layer is improved, so that the resistance increase in the high load charge / discharge cycle can be suppressed.

In the present specification, the central portion of the positive electrode active material layer is, in principle, when the electrode on which the positive electrode active material layer is arranged is viewed from above, the estimated line dividing the region does not intersect with any end of the electrode. Although it refers to a closed region, when the estimation line separating the regions overlaps with a pair of electrode ends facing each other, the central portion of the positive electrode active material layer also overlaps with a maximum of three sides of the continuous electrode ends. It shall include.
In the present specification, the outer peripheral portion of the positive electrode active material layer means a portion excluding the central portion of the positive electrode active material layer.

For example, when the electrode laminate is a laminate of single-wafer electrodes, according to the above definition, as shown in FIG. 1, from each of the four sides (the length is x or y) of the positive electrode end. A 5% length position (0.05x or 0.05y position) can be defined as the outer peripheral portion (4) of the positive electrode active material layer (2), thereby the positive electrode active material layer (2). The peripheral edge of the central part (3) of the above is also determined.
Further, when the electrode stack is wound laminate, as illustrated in FIG. 2, the longitudinal direction of the length of the electrode when projected view from the direction perpendicular to the winding center axes x ₂ The wound laminate is cut at the position of, and the central portion (3) and the outer peripheral portion (4) of the positive electrode active material are defined by using the open (that is, rewound) positive electrode. Further, as shown in FIG. 3, the length x ₂ of the cut-out wound laminated body in the long direction includes the cut-out wound laminated body (6) in the exterior body (7), which is non-aqueous lithium. It roughly corresponds to the electrode length in the long direction of the power storage element.

The method of making the amount of the alkali metal compound in the central portion of the positive electrode active material layer smaller than that in the outer peripheral portion is not particularly limited, and for example, the central portion of the non-aqueous lithium power storage element is heated during the lithium doping treatment described later. More specifically, a method for accelerating the decomposition of the alkali metal compound in the central portion of the positive electrode active material layer by heating the central portion at 35 ° C. or higher and lower than 80 ° C., preferably 40 ° C. or higher and 60 ° C. or lower. , A method of lowering the concentration of the alkali metal compound in the central portion of the positive electrode active material layer when producing the positive electrode precursor and the like can be mentioned.

The alkali metal compound contained in the positive electrode active material layer in the positive electrode gradually decomposes and gasifies when exposed to a high potential of about 4.0 V or more, and the generated gas diffuses ions in the electrolytic solution. It causes an increase in resistance because it inhibits it. Therefore, it is preferable to form a film composed of a fluorine-containing compound on the surface of the alkali metal compound to suppress the reaction of the alkali metal compound.

The method for forming a film composed of a fluorine-containing compound on the surface of the alkali metal compound is not particularly limited, but a fluorine-containing compound that decomposes at a high potential is contained in the electrolytic solution, and the non-aqueous lithium storage element is made of the fluorine-containing compound. Examples thereof include a method of applying a high voltage higher than the decomposition potential and a method of applying a temperature higher than the decomposition temperature.

Coverage of fluorine compound coated on the surface of the lithium compound, the fluorine mapping for oxygen mapping in SEM-EDX image of the cathode surface and the area overlapping ratio A _1, fluorine mapping for oxygen mapping in SEM-EDX image of the positive electrode section it can be represented by the area overlap rate a _2.

The overlap rate A ₁ is preferably 40% or more and 99% or less. When the overlap ratio A ₁ is 40% or more, decomposition of an alkali metal compound such as a lithium compound can be suppressed. When the overlap ratio A ₁ is 99% or less, the vicinity of the positive electrode can be kept basic, so that the high load charge / discharge cycle characteristics are excellent.

The overlap rate A ₁ is obtained by calculating the area overlap rate of the fluorine mapping with respect to the oxygen mapping binarized based on the average value of the brightness in the element mapping obtained by SEM-EDX on the positive electrode surface.

The measurement conditions for element mapping of SEM-EDX are not particularly limited, but the number of pixels is preferably in the range of 128 × 128 pixels to 512 × 512 pixels, the brightness does not reach the maximum brightness, and the average brightness is achieved. It is preferable to adjust the brightness and contrast so that the value falls within the range of 40% to 60% brightness.

The area overlap rate A ₂ is the area overlap rate of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness in the element mapping obtained by SEM-EDX of the positive electrode cross section processed by broad ion beam (BIB). It is measured by calculating. The BIB process is a process of irradiating an Ar beam from the upper part of the positive electrode to produce a smooth cross section along the edge of the shielding plate installed directly above the sample.

The overlap rate A ₂ is preferably 10% or more and 60% or less. When the overlap ratio A ₂ is 10% or more, decomposition of an alkali metal compound such as a lithium compound can be suppressed. When the overlap ratio A ₂ is 60% or less, the inside of the alkali metal compound such as a lithium compound is not fluorinated, so that the vicinity of the positive electrode can be kept basic, resulting in high load charge / discharge cycle characteristics. Excellent.

(Other components of the positive electrode active material layer)
The positive electrode active material layer in the present embodiment may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material and the alkali metal compound, if necessary.

Examples of the conductive filler include a conductive carbonaceous material having higher conductivity than the positive electrode active material. As the conductive filler, for example, Ketjen black, acetylene black, vapor-grown carbon fiber, graphite, carbon nanotubes, a mixture thereof and the like are preferable.

The mixing amount of the conductive filler in the positive electrode active material layer is preferably more than 0 to 20 parts by mass, and more preferably 1 to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material. From the viewpoint of high input, the positive electrode active material layer preferably contains a conductive filler. When the mixing amount of the conductive filler in the positive electrode active material layer is 20 parts by mass or less, the content ratio of the positive electrode active material in the positive electrode active material layer is large, and the energy density per volume of the positive electrode active material layer can be secured.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used. 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 further preferably 5 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the positive electrode active material. It is less than a part. When the amount of the binder is 1% by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the ingress and egress and diffusion of ions into the positive electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the dispersion stabilizer used is preferably more than 0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the ingress and egress and diffusion of ions into the positive electrode active material.

[Positive current collector]
The material constituting the positive electrode current collector in the present embodiment is not particularly limited as long as it has high electron conductivity and is unlikely to deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions. Foil is preferred. Aluminum foil is particularly preferable as the positive electrode current collector in the non-aqueous lithium storage element of the present embodiment.

The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. A metal foil having through holes such as an etching foil may be used.

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, but is preferably 1 to 100 μm, for example. When the positive electrode current collector has holes or irregularities, the thickness of the positive electrode current collector shall be measured based on the portion where the holes or irregularities do not exist.

[Manufacturing of positive electrode precursor]
In the present embodiment, the positive electrode precursor serving as the positive electrode of the non-aqueous lithium storage element can be manufactured by a technique for manufacturing electrodes in known 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 necessary are dispersed or dissolved in water or an organic solvent to prepare a slurry coating solution, and this coating solution is used. A positive electrode precursor can be obtained by coating on one or both sides of a positive electrode current collector to form a coating film and drying the coating. The obtained positive electrode precursor may be pressed to adjust the film thickness and bulk density of the positive electrode active material layer. Alternatively, without the use of a solvent, the positive electrode active material and the alkali metal compound, and any other optional components used as needed, are dry mixed, the resulting mixture is press molded and then conductive. It is also possible to attach it to the positive electrode current collector using an adhesive.

The coating liquid of the positive electrode precursor was obtained by dry-blending a part or all of various material powders including the positive electrode active material, and then water or an organic solvent and / or a binder or a dispersion stabilizer was dissolved or dispersed therein. Liquid or slurry substances may be added and prepared. A coating liquid may be prepared by adding various material powders containing a positive electrode active material to a liquid or slurry substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. As a method of dry blending, for example, a positive electrode active material and an alkali metal compound are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed to coat a low conductive alkali metal compound with a conductive material. You may do. As a result, the lithium compound is easily decomposed in the positive electrode precursor in the lithium doping step described later. When water is used as the solvent of the coating liquid, the coating liquid may become alkaline by adding an alkali metal compound, so a pH adjuster may be added if necessary.

The dissolution or dispersion method is not particularly limited, but a homodisper, a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirling high-speed mixer, or the like can be preferably used. In order to obtain a coating liquid in a well-dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. When the peripheral speed is 1 m / s or more, various materials are preferably dissolved or dispersed. When the peripheral speed is 50 m / s or less, various materials are not easily destroyed by heat or shearing force due to dispersion, and reaggregation is reduced, which is preferable.

The dispersity of the coating liquid is preferably such that the particle size measured by the grain gauge is 0.1 μm or more and 100 μm or less. The upper limit of the dispersity is more preferably 80 μm or less in particle size, and further preferably 50 μm or less in particle size. The particle size of 0.1 μm or more means that various material powders containing the positive electrode active material are not excessively crushed during the preparation of the coating liquid. Further, when the particle size is 100 μm or less, clogging at the time of discharging the coating liquid and streaks of the coating film are less likely to occur, and stable coating can be performed.

The viscosity (ηb) of the coating liquid of the positive electrode precursor is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1, It is 700 mPa · s or more and 5,000 mPa · s or less. When the viscosity (ηb) of the coating liquid of the positive electrode precursor is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and thickness can be satisfactorily controlled. When the viscosity (ηb) of the coating liquid of the positive electrode precursor is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, which is desired. It can be controlled to be less than or equal to the coating film thickness of.

The TI value (thixotropy index value) of the coating liquid of the positive electrode precursor is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. When the TI value of the coating liquid of the positive electrode precursor is 1.1 or more, the coating film width and thickness can be satisfactorily controlled.

The method for forming the coating film of the positive electrode precursor is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. In the case of multi-layer coating, the composition of the coating liquid may be adjusted so that the content of the lithium compound in each layer of the coating film is different. 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 further preferably 1 m / min or more and 50 m / min or less. When the coating speed is 0.1 m / min or more, stable coating can be performed, and when the coating speed is 100 m / min or less, sufficient coating accuracy can be ensured.

The method for drying the coating film of the positive electrode precursor is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Moreover, you may dry by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. When the drying temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the positive electrode current collector and the positive electrode active material layer can be suppressed.

The method for pressing the positive electrode precursor is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the positive electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The press 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 further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. When the press pressure is 20 kN / cm or less, the positive electrode precursor is less likely to bend or wrinkle, and the desired thickness and bulk density of the positive electrode active material layer film can be easily adjusted.
The gap between the press rolls can be set to an arbitrary value according to the film thickness of the positive electrode precursor after drying so as to have a desired film thickness and bulk density of the positive electrode active material layer.
The press speed can be set to any speed so as to reduce the deflection and wrinkles of the positive electrode precursor.
The surface temperature of the press portion may be room temperature, or the surface of the press portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used at minus 60 ° C. or higher, more preferably the melting point of the binder at minus 45 ° C. or higher, and even more preferably the melting point of the binder at minus 30 ° C. It is above ℃. The upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder to be used plus 50 ° C. or less, more preferably the melting point of the binder plus 30 ° C. or lower, and even more preferably the melting point of the binder plus 20. It is below ° C. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferably pressed to 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. Heat the surface of the part. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferably pressed to 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. or higher and 120 ° C. or lower. Warm the surface of the part.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a temperature rise rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.

The press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less per one 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 further preferably 30 μm or more and 80 μm or less per side surface. When the thickness of the positive electrode active material layer is 20 μm or more, sufficient charge / discharge capacity can be exhibited. When the thickness of the positive electrode active material layer is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, when the thickness of the positive electrode current collector layer is 20 μm or more and 200 μm or less, sufficient output characteristics can be obtained, the cell volume can be reduced, and therefore the energy density can be increased. The thickness of the positive electrode active material layer when the positive electrode current collector has through holes or irregularities is the thickness of the positive electrode active material layer per side in a portion of the positive electrode current collector that does not have through holes or irregularities. The average value.

The bulk density of the positive electrode active material layer in the positive electrode after the lithium doping step described later is preferably in the range of 0.40 g / cm ³ or more, more preferably 0.50 g / cm ³ or more and 1.3 g / cm ³ or less. When the bulk density of the positive electrode active material layer is 0.40 g / cm ³ or more, a high energy density can be exhibited and the miniaturization of the power storage element can be achieved. When the bulk density of the positive electrode active material layer is 1.3 g / cm ³ or less, the electrolytic solution is sufficiently diffused in the pores in the positive electrode active material layer, and high output characteristics can be obtained.

<Negative electrode>
The negative electrode in the present embodiment has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one or both sides of the current collector.

[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material, and may contain an optional component such as a conductive filler, a binder, and a dispersant stabilizer, if necessary.

[Negative electrode active material]
As the negative electrode active material, a substance capable of occluding and releasing lithium ions can be used. Specific examples of the negative electrode active material include carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin, and tin compounds. The content of the carbon material is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total mass of the negative electrode active material. The content of the carbon material may be 100% by mass, but from the viewpoint of obtaining a good effect when used in combination with other materials, for example, it is preferably 90% by mass or less, preferably 80% by mass or less. May be good.

Examples of the carbon material include non-graphitizable carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon spherules; graphite whiskers; Amorphous carbonaceous material; carbonaceous material obtained by heat-treating carbon precursors such as petroleum-based pitch, coal-based pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenolic resin, etc.); Alternatively, thermal decomposition products of novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof can be mentioned.
As the carbon material, activated carbon, carbon black, template porous carbon, high specific surface area graphite, carbon nanoparticles, pitch composite carbon material and the like can be preferably used.

Among these, from the viewpoint of lowering the resistance of the negative electrode, a pitch composite carbon material which can be obtained by heat treatment in a state where one or more carbon materials and a petroleum-based pitch or a coal-based pitch coexist is preferable. The carbon material and pitch may be mixed at a temperature above the melting point of the pitch prior to the heat treatment. The heat treatment temperature may be any temperature as long as the pitch used is a temperature at which the component generated by volatilization or thermal decomposition becomes a carbonaceous material. A non-oxidizing atmosphere is preferable as the atmosphere for performing the heat treatment.

Preferred examples of the pitch composite carbon material are the pitch composite carbon materials 1 and 2 described later. Either one of these may be used, or both of them may be used in combination.

In the specification of the present application, the pitch composite carbon material 1 is ^{one or more carbon materials having a BET specific surface area of 100 m 2} / g or more and 3000 m ² / g or less, and a petroleum-based pitch or a coal-based pitch coexist. It is a material that can be obtained by heat treatment in a state.

In one embodiment, the BET specific surface area of the pitch composite carbon material 1 ^{is preferably 100 m 2} / g or more and 1,500 m ² / g or less.

In one embodiment, the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is preferably 530 mAh / g or more and 2,500 mAh / g or less, more preferably 620 mAh / g or more and 2,100 mAh / g or less, and further. It is preferably 760 mAh / g or more and 1,700 mAh / g or less, and even more preferably 840 mAh / g or more and 1,500 mAh / g or less.

Doping lithium ions lowers the negative electrode potential. Therefore, when the negative electrode containing the negative electrode active material doped with lithium ions is combined with the positive electrode, the voltage of the non-aqueous lithium storage element becomes high and the utilization capacity of the positive electrode becomes large. Therefore, the capacity and energy density of the obtained non-aqueous lithium storage element are increased.

If the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is 530 mAh / g or more, the lithium ions are well doped even at irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 1 are inserted. Further, the amount of the negative electrode active material with respect to the desired amount of lithium ions can be reduced. Therefore, the film thickness of the negative electrode can be reduced, and a high energy density can be obtained. The larger the doping amount, the lower the negative electrode potential, and the input / output characteristics, energy density, and durability are improved.
On the other hand, if the doping amount of lithium ions per unit mass of the pitch composite carbon material 1 is 2,500 mAh / g or less, side effects such as precipitation of lithium metal are less likely to occur.

The pitch composite carbon material 2 is a ^{heat-treated state in which one or more carbon materials having a BET specific surface area of 1 m 2} / g or more and 30 m ² / g or less coexist with a petroleum-based pitch or a coal-based pitch. It is a material that can be obtained.

In another embodiment, it is also preferable that the BET specific surface area of the pitch composite carbon material 2 is 1 m ² / g or more and 50 m ^{2 / g or less.}

In another embodiment, the doping amount of lithium ions per unit mass of the negative electrode active material 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, still more preferably 90 mAh / g. It is 600 mAh / g or more, more preferably 100 mAh / g or more and 550 mAh / g or less.

If the doping amount of lithium ions per unit mass of the pitch composite carbon material 2 is 50 mAh / g or more, the lithium ions are well doped even at irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 2 are inserted. Therefore, a high energy density can be obtained. The larger the doping amount, the lower the negative electrode potential, and the input / output characteristics, energy density, and durability are improved.
On the other hand, if the doping amount of lithium ions per unit mass of the pitch composite carbon material 2 is 700 mAh / g or less, side effects such as precipitation of lithium metal are less likely to occur.

The amount of lithium ion doping (mAh / g) of the negative electrode active material in the non-aqueous lithium storage device at the time of shipment and after use in the present embodiment can be known as follows, for example.
First, the negative electrode active material layer in the present embodiment is washed with ethyl methyl carbonate or dimethyl carbonate and air-dried, and then an extract extracted with a mixed solvent consisting of methanol and isopropanol and an extracted negative electrode active material layer are obtained. This extraction is typically performed in an Ar box at an environmental temperature of 23 ° C.
The amount of lithium contained in the extract obtained as described above and the negative electrode active material layer after extraction is quantified using, for example, ICP-MS (inductively coupled plasma mass spectrometer), and the total thereof. The amount of lithium ion doped in the negative electrode active material can be known by determining. The obtained value may be allocated by the amount of the negative electrode active material used for extraction to calculate the amount of lithium ion doping (mAh / g).

The average particle size of the pitch composite carbon materials 1 and 2 is preferably 1 μm or more and 10 μm or less. The lower limit of the average particle size is more preferably 2 μm or more, still more preferably 2.5 μm or more. The upper limit of the average particle size is more preferably 6 μm or less, still more preferably 4 μm or less. When the average particle size of the negative electrode active material is 1 μm or more and 10 μm or less, good durability is maintained.

(Other components of the negative electrode active material layer)
The negative electrode active material layer in the present embodiment may contain an optional component such as a conductive filler, a binder, and a dispersant stabilizer, if necessary, in addition to the negative electrode active material.

The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor-grown carbon fiber. The amount of the 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 further preferably more than 0 parts by mass and 15 parts by mass with respect to 100 parts by mass of the negative electrode active material. It is less than a part.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer and the like. Can be used. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 2 parts by mass or more and 27 parts by mass or less, and further preferably 3 parts by mass or more and 25 parts by mass with respect to 100 parts by mass of the negative electrode active material. It is less than a part. When the amount of the binder is 1% by mass or more, sufficient electrode strength is exhibited. When the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without hindering the entry and exit of lithium ions into the negative electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative 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 with respect to 100 parts by mass of the negative electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of lithium ions into the negative electrode active material.

[Negative electrode current collector]
The material constituting the negative electrode current collector in the present embodiment is preferably a metal foil having high electron conductivity and less likely to be deteriorated due to elution into an electrolytic solution and reaction with an electrolyte or ions. Such metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. Copper foil is preferable as the negative electrode current collector in the non-aqueous lithium storage element of the present embodiment.

The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. A metal foil having through holes such as an etching foil may be used.
The thickness of the negative electrode current collector is not particularly limited as long as the shape and strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example. When the negative electrode current collector has holes or irregularities, the thickness of the negative electrode current collector shall be measured based on the portion where the holes or irregularities do not exist.

[Manufacturing 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. Typically, the negative electrode active material layer is fixed on one or both sides of the negative electrode current collector.

The negative electrode can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, various materials including a negative electrode active material are dispersed or dissolved in water or an organic solvent to prepare a slurry coating liquid, and this coating liquid is applied to one or both sides of a negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying the coating film. The obtained negative electrode may be pressed to adjust the film thickness and bulk density of the negative electrode active material layer. Alternatively, a method in which various materials including a negative electrode active material are mixed in a dry manner without using a solvent, the obtained mixture is press-molded, and then attached to a negative electrode current collector using a conductive adhesive. Is also possible.

The coating liquid is a liquid or slurry in which a part or all of various material powders including the negative electrode active material is dry-blended, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved or dispersed therein. The substance of the above may be added and prepared. Further, various material powders containing a negative electrode active material may be added to a liquid or slurry substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent to prepare a coating liquid. ..

The dissolution or dispersion method is not particularly limited, but a homodisper, a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirl type high-speed mixer, or the like can be preferably used. In order to obtain a coating liquid in a well-dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. When the peripheral speed is 1 m / s or more, various materials are preferably dissolved or dispersed. When the peripheral speed is 50 m / s or less, various materials are not easily destroyed by heat or shearing force due to dispersion, and reaggregation is reduced, which is preferable.

The viscosity (ηb) of the coating liquid of the negative electrode is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1,700 mPa · s. It is s or more and 5,000 mPa · s or less. When the viscosity (ηb) of the coating liquid of the negative electrode is 1,000 mPa · s or more, the liquid dripping at the time of forming the coating film is suppressed, and the width and thickness of the coating film can be satisfactorily controlled. When the viscosity (ηb) of the coating liquid of the negative electrode is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the desired coating can be performed. It can be controlled below the film thickness.

The TI value (thixotropy index value) of the coating liquid of the negative electrode is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. When the TI value of the coating liquid of the negative electrode is 1.1 or more, the coating film width and thickness can be satisfactorily controlled.

The method for forming the coating film on the negative electrode is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by a single-layer coating or a multi-layer coating. 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 further preferably 1 m / min or more and 50 m / min or less. When the coating speed is 0.1 m / min or more, stable coating can be performed, and when the coating speed is 100 m / min or less, sufficient coating accuracy can be ensured.

The method for drying the coating film of the negative electrode is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Moreover, you may dry by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. When the drying temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the negative electrode current collector and the negative electrode active material layer can be suppressed.

The method of pressing the negative electrode is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the negative electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The press 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 further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. When the press pressure is 20 kN / cm or less, the negative electrode is less likely to bend or wrinkle, and it is easy to adjust the film thickness and bulk density of the negative electrode active material layer film.
The gap between the press rolls can be set to an arbitrary value according to the film thickness of the negative electrode after drying so as to have a desired film thickness and bulk density of the negative electrode active material layer.
The press speed can be set to any speed so as to reduce bending and wrinkles of the negative electrode.
The surface temperature of the press portion may be room temperature, or the surface of the press portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used at minus 60 ° C. or higher, more preferably the melting point of the binder at minus 45 ° C. or higher, and even more preferably the melting point of the binder at minus 30 ° C. It is above ℃. The upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder to be used plus 50 ° C. or less, more preferably the melting point of the binder plus 30 ° C. or lower, and even more preferably the melting point of the binder plus 20. It is below ° C. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferably pressed to 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. Heat the surface of the part. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferably pressed to 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. or higher and 120 ° C. or lower. Warm the surface of the part.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a temperature rise rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.

The press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per one side of the negative electrode current collector. The lower limit of the thickness of the negative electrode active material layer is more preferably 7 μm or more, still more preferably 10 μm or more. The upper limit of the thickness of the negative electrode active material layer is more preferably 80 μm or less, and further preferably 60 μm or less. When the thickness of the negative electrode active material layer is 5 μm or more, streaks and the like are less likely to occur when the negative electrode active material layer is applied, and the coatability is excellent. When the thickness of the negative electrode active material layer is 100 μm or less, a high energy density can be developed by reducing the cell volume. The thickness of the negative electrode active material layer when the negative electrode current collector has through holes or irregularities is the thickness of the negative electrode active material layer per side in a portion of the negative electrode current collector that does not have through holes or irregularities. The average value.

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 further preferably 0.45 g. / Cm ³ or more and 1.3 g / cm ³ or less. When the bulk density of the negative electrode active material layer is 0.30 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the negative electrode active materials can be exhibited. When the bulk density of the negative electrode active material layer is 1.8 g / cm ³ or less, pores in which ions can be sufficiently diffused can be secured in the negative electrode active material layer.

The BET specific surface area, the amount of mesopores, and the amount of micropores in the present embodiment are values obtained by the following methods, respectively.
The sample is vacuum-dried at 200 ° C. for 24 hours, and the isotherms of adsorption and desorption are measured using nitrogen as an adsorbent. Using the isotherms on the adsorption side obtained here, the BET specific surface area is calculated by the BET multipoint method or the BET1 point method, the mesopore amount is calculated by the BJH method, and the micropore amount is calculated by the MP method.

The BJH method is a calculation method generally used for analysis of mesopores, and was proposed by Barrett, Joiner, Hallenda et al. (EP Barrett, LG Joiner and P. Hallenda, J. Am. Chem. Soc., 73,373 (1951)).

The MP method is a micropore volume, a micropore area, and a micropore using the "t-plot method" (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)). It means a method for obtaining the distribution of R. S. It is a method devised by Mikhair, Brunauer, Bodor (RS Mikhair, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).

<Separator>
The positive electrode precursor and the negative electrode are generally laminated or wound through a separator to form an electrode laminate having a positive electrode precursor, a negative electrode, and a separator.

As the separator, a polyethylene microporous membrane or polypropylene microporous membrane used in a lithium ion secondary battery, a cellulose non-woven paper used in an electric double layer capacitor, or the like can be used. A film composed of organic or inorganic fine particles may be laminated on one side or both sides of these separators. Further, organic or inorganic fine particles may be contained inside the separator.

The thickness of the separator is preferably 5 μm or more and 35 μm or less. When the thickness of the separator is 5 μm or more, self-discharge due to internal micro shorts tends to be small, which is preferable. When the thickness of the separator is 35 μm or less, the output characteristics of the power storage element tend to be high, which is preferable.

The thickness of the film composed of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. When the thickness of the film composed of organic or inorganic fine particles is 1 μm or more, self-discharge due to internal microshorts tends to be small, which is preferable. It is preferable that the thickness of the film composed of organic or inorganic fine particles is 10 μm or less because the output characteristics of the power storage element tend to be high.

<Exterior body>
As the exterior body, a metal can, a laminated film, or the like can be used. The metal can is preferably made of aluminum. As the laminated film, a film in which a metal foil and a resin film are laminated is preferable, and for example, a laminated film composed of three layers of an outer layer resin film / metal foil / inner layer resin film is exemplified. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and a resin such as nylon or polyester can be preferably used. The metal foil is for preventing the permeation of moisture and gas, and foils such as copper, aluminum, and stainless steel can be preferably used. Further, the inner layer resin film is for protecting the metal foil from the electrolytic solution stored inside and for melting and sealing the outer body at the time of heat sealing, and polyolefins, acid-modified polyolefins and the like can be preferably used.

<Non-aqueous electrolyte solution>
The electrolytic solution in this embodiment is a non-aqueous electrolytic solution containing lithium ions. The non-aqueous electrolyte solution contains a non-aqueous solvent described later. The non-aqueous electrolyte solution preferably contains 0.5 mol / L or more of a lithium salt based on the total volume of the non-aqueous electrolyte solution.

The non-aqueous electrolyte solution in the present embodiment contains, as lithium salts, for example, (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO _2). CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₄ H), LiC (SO ₂ F) ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂₎ C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , MC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF _4, etc. can be used alone, or two or more of them may be mixed and used. It is preferable to contain _{LiPF 6} and / or LiN (SO ₂ F) ₂ because it can exhibit high conductivity.

The lithium salt concentration in the non-aqueous electrolyte solution is preferably 0.5 mol / L or more, more preferably 0.5 to 2.0 mol / L. When the lithium salt concentration is 0.5 mol / L or more, anions are sufficiently present, so that the capacity of the power storage element can be sufficiently increased. Further, when the lithium salt concentration is 2.0 mol / L or less, it is possible to prevent undissolved lithium salt from precipitating in the non-aqueous electrolytic solution and the viscosity of the electrolytic solution from becoming too high, resulting in a decrease in conductivity. It is preferable because it does not reduce the output characteristics.

The non-aqueous electrolyte solution in the present embodiment preferably contains a cyclic carbonate and a chain carbonate as a non-aqueous solvent. It is advantageous that the non-aqueous electrolyte solution contains a cyclic carbonate and a chain carbonate in that it dissolves a lithium salt having a desired concentration and that it exhibits high lithium ion conductivity. Examples of the cyclic carbonate include alkylene carbonate compounds typified by ethylene carbonate, propylene carbonate, butylene carbonate and the like. The alkylene carbonate compound is typically unsubstituted. Examples of the chain carbonate include dialkyl carbonate compounds typified by dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, dibutyl carbonate and the like. Dialkyl carbonate compounds are typically unsubstituted.

The total content of the cyclic carbonate and the chain carbonate is preferably 50% by mass or more, more preferably 65% by mass or more, preferably 95% by mass or less, more preferably more preferably, based on the total mass of the non-aqueous electrolyte solution. It is 90% by mass or less. When the total content of the cyclic carbonate and the chain carbonate is 50% by mass or more, the lithium salt having a desired concentration can be dissolved, and high lithium ion conductivity can be exhibited. When the total concentration of the cyclic carbonate and the chain carbonate is 95% by mass or less, the electrolytic solution can further contain the additives described later.

The non-aqueous electrolyte solution in the present embodiment may further contain an additive. The additive is not particularly limited, and examples thereof include sultone compounds, cyclic phosphazene, acyclic fluorinated ethers, fluorinated cyclic carbonates, cyclic carbonates, cyclic carboxylic acid esters, and cyclic acid anhydrides. It can be used alone, or a mixture of two or more.

<Manufacturing method of non-aqueous lithium storage element>
[Assembly process]
In the assembly process of one embodiment, for example, a positive electrode terminal and a negative electrode terminal are connected to a laminate formed by laminating a positive electrode precursor and a negative electrode cut into a single-wafer shape via a separator to form an electrode laminate. To make. In another embodiment, the positive electrode precursor and the negative electrode may be laminated and wound via a separator, and the positive electrode terminal and the negative electrode terminal may be connected to the wound body to prepare the electrode wound body. The shape of the electrode winding body may be cylindrical or flat.

The method of connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, but a method such as resistance welding or ultrasonic welding can be used.

It is preferable to remove the residual solvent by drying the electrode laminate or the electrode winding body to which the terminals are connected. The drying method is not limited, but it can be dried by vacuum drying or the like. The residual solvent is preferably 1.5% by mass or less based on the total mass of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics are deteriorated, which is not preferable.

The dried electrode laminate or electrode wound body is preferably stored in an exterior body typified by a metal can or a laminate film in a dry environment with a dew point of −40 ° C. or lower, and a non-aqueous electrolyte solution is injected. It is preferable to seal by leaving only one opening for the purpose. If the dew point is higher than −40 ° C., water adheres to the electrode laminate or the electrode wound body, water remains in the system, and the self-discharge characteristics are deteriorated, which is not preferable. The method for sealing the exterior body is not particularly limited, but a method such as heat sealing or impulse sealing can be used.

[Liquid injection, impregnation, sealing process]
After the assembly process, the non-aqueous electrolyte solution is injected into the electrode laminate housed in the exterior body. After pouring, it is desirable to further impregnate and sufficiently immerse the positive electrode, negative electrode, and separator with a non-aqueous electrolyte solution. When the electrolytic solution is not immersed in at least a part of the positive electrode, the negative electrode, and the separator, the lithium doping proceeds non-uniformly in the lithium doping step described later, so that the resistance of the obtained non-aqueous lithium storage element increases. Or the durability is reduced. The method of impregnation is not particularly limited, but for example, the electrode laminate after injection is installed in a decompression chamber with the outer body open, the inside of the chamber is decompressed using a vacuum pump, and the pressure is increased again. A method of returning to atmospheric pressure or the like can be used. After impregnation, the electrode laminate with the outer body open can be sealed by sealing while reducing the pressure.

[Lithium dope process]
In the lithium doping step, a voltage is applied between the positive electrode precursor and the negative electrode to decompose the lithium compound in the positive electrode precursor to release lithium ions, and the lithium ions are reduced at the negative electrode to reduce the negative electrode active material layer. It is preferable to pre-dope the lithium ion.

_{In the lithium doping step, gas such as CO 2} is generated due to oxidative decomposition of the lithium compound in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to take measures to release the generated gas to the outside of the exterior body. As this means, for example, a method of applying a voltage with a part of the exterior body opened; a state in which an appropriate gas release means such as a gas vent valve or a gas permeable film is installed in advance on a part of the exterior body. A method of applying a voltage; etc. can be mentioned.

[Aging process]
After the lithium doping step, it is preferable to age the electrode laminate. In the aging step, the solvent in the electrolytic solution is decomposed at the negative electrode, and a lithium ion permeable solid polymer film is formed on the surface of the negative electrode.

The aging method is not particularly limited, but for example, a method of reacting the solvent in the electrolytic solution in a high temperature environment or the like can be used.

[Degassing process]
After the aging step, it is preferable to further degas to surely remove the gas remaining in the electrolytic solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the electrolytic solution, the positive electrode, and the negative electrode, ion conduction is inhibited, so that the resistance of the obtained non-aqueous lithium storage element increases.

The method of degassing is not particularly limited, but for example, a method of installing the electrode laminate in the decompression chamber with the exterior body open and depressurizing the inside of the chamber using a vacuum pump can be used. .. After degassing, the exterior body is sealed to seal the exterior body, and a non-aqueous lithium storage element can be manufactured.

<Characteristic evaluation of non-aqueous lithium storage element>
[Capacitance]
In the present specification, the capacitance Fa (F) is a value obtained by the following method.
First, in a constant temperature bath in which the cell corresponding to the non-aqueous lithium storage element is set to 25 ° C, constant current charging is performed until the current value of 2C reaches 3.8V, and then a constant voltage of 3.8V is applied. Perform constant voltage charging for a total of 30 minutes. After that, the capacitance when a constant current discharge is performed with a current value of 2C up to 2.2V is defined as Q (C). Using the Q and the voltage change ΔV _x (V) obtained here, the value calculated by the capacitance Fa = Q / ΔV _x = Q / (3.8-2.2) is calculated as the capacitance Fa. It is called (F).
Here, the current discharge rate (also referred to as "C rate") is the relative ratio of the current at the time of discharge to the discharge capacity, and generally, when performing constant current discharge from the upper limit voltage to the lower limit voltage, it takes 1 hour. The current value at which the discharge is completed is called 1C. In the present specification, 1C is the current value at which the discharge is completed in 1 hour when the constant current discharge is performed from the upper limit voltage of 3.8 V to the lower limit voltage of 2.2 V.

[Internal resistance]
In the present specification, the internal resistance Ra (Ω) is a value obtained by the following method:
First, the non-aqueous lithium storage element is charged with a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V with a current value of 20 C, and then a constant voltage charge with a constant voltage of 3.8 V is applied. Perform for a total of 30 minutes. Subsequently, the sampling interval is set to 0.1 seconds, and constant current discharge is performed up to 2.2 V at a current value of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time points of the discharge time of 2 seconds and 4 seconds is Eo, the drop voltage ΔE = 3.8- It is a value calculated from Eo as Ra = ΔE / (current value of 20C).

[High load charge / discharge cycle test]
In the present specification, the resistance change rate and the amount of gas generated after the high load charge / discharge cycle test are measured by the following methods.
(Resistance change rate after high load charge / discharge cycle)
First, the cell corresponding to the non-aqueous lithium storage element is charged at a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V at a current value of 200 C, and then to 2.2 V at a current value of 200 C. Discharge with constant current until it reaches the point. This high load charge / discharge cycle is repeated 60,000 times, and the internal resistance Rb after the high load charge / discharge cycle is measured according to the above method for measuring internal resistance. Let Rb / Ra be the rate of change in resistance after a high load charge / discharge cycle.

(Gas generated after high load charge / discharge cycle)
In the present specification, the volume of the non-aqueous lithium storage element is measured by the Archimedes method. The solvent used for the volume measurement by the Archimedes method is not particularly limited, but it is preferable to use a solvent having an electric conductivity of 10 μS / cm or less and which does not cause electrolysis when the non-aqueous lithium storage element is immersed. For example, pure water and a fluorine-based inert liquid are preferably used. In particular, from the viewpoint of having a high specific density and excellent electrical insulation, fluorine-based inert liquids such as Fluorinert (registered trademark, 3M Japan Ltd.) FC-40, FC-43 and the like are preferably used. When the volume of the non-aqueous lithium storage element before the high load charge / discharge cycle is Va and the volume of the non-aqueous lithium storage element after the high load charge / discharge cycle is Vb, Vb-Va is the gas after the high load charge / discharge cycle. Let the generated amount be V.

<Method of identifying alkali metal compounds in electrodes>
The method for identifying the alkali metal compound such as the lithium compound contained in the positive electrode is not particularly limited, but can be identified by, for example, the following method. For the identification of the alkali metal compound, it is preferable to identify by combining a plurality of analysis methods described below.

When measuring SEM-EDX, Raman, or XPS described below, disassemble the non-aqueous lithium storage element in an argon box, take out the positive electrode, clean the electrolyte adhering to the surface of the positive electrode, and then perform the measurement. Is preferable. As for the method for cleaning the positive electrode, since the electrolyte adhering to the surface of the positive electrode may be washed away, a carbonate solvent such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate can be preferably used. As a cleaning method, for example, the positive electrode is immersed in a diethyl carbonate solvent 50 to 100 times the weight of the positive electrode for 10 minutes or more, and then the solvent is replaced and the positive electrode is immersed again. Then, the positive electrode is taken out from diethyl carbonate, vacuum dried, and then analyzed by SEM-EDX, Raman spectroscopy, and XPS. The vacuum drying conditions are such that the residual diethyl carbonate in the positive electrode is 1% by mass or less in the range of temperature: 0 to 200 ° C., pressure: 0 to 20 kPa, and time: 1 to 40 hours. The residual amount of diethyl carbonate can be quantified based on a calibration curve prepared in advance by measuring the GC / MS of the water after washing with distilled water and adjusting the liquid amount, which will be described later.

In ion chromatography described later, anions can be identified by analyzing the water after washing the positive electrode with distilled water.

If the alkali metal compound cannot be identified by the analysis method, other analysis methods include ⁷ Li-solid NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), and AES (Auger). Alkali metal compounds can also be identified by using electron spectroscopy), TPD / MS (mass spectrometry of heated generated gas), DSC (differential scanning calorimeter analysis) and the like.

[Scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX)]
The alkali metal compound and the positive electrode active material can be identified by oxygen mapping using an SEM-EDX image of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As a measurement example of the SEM-EDX image, the acceleration voltage is 10 kV, the emission current is 1 μA, the number of measurement pixels is 256 × 256 pixels, and the number of integrations is 50. In order to prevent the sample from being charged, gold, platinum, osmium or the like can be surface-treated by a method such as vacuum deposition or sputtering. Regarding the method for measuring the SEM-EDX image, it is preferable to adjust the brightness and contrast so that the brightness does not reach the maximum brightness and the average value of the brightness is in the range of 40% to 60%. When the obtained oxygen mapping is binarized based on the average value of brightness, the particles containing 50% or more of the bright part in the area are defined as the alkali metal compound.

[Microscopic Raman spectroscopy]
The alkali metal compound and the positive electrode active material can be identified by Raman imaging of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As an example of measurement conditions, the excitation light is 532 nm, the excitation light intensity is 1%, the long operation of the objective lens is 50 times, the diffraction grating is 1800 gr / mm, the mapping method is point scanning (slit 65 mm, binning 5 pix), 1 mm step, The exposure time per point can be measured for 3 seconds, the number of integrations can be measured once, and the measurement can be performed under the condition of having a noise filter. For the measured Raman spectrum ^{, a straight baseline is set in the range of 1071 to 1104 cm -1} , the area is calculated with a positive value from the baseline as the peak of carbonate ions, and the frequency is integrated. At this time, the frequency with respect to the carbonate ion peak area approximated by the Gaussian function of the noise component is subtracted from the carbonate ion frequency distribution.

[X-ray Photoelectron Spectroscopy (XPS)]
The bonding state of the alkali metal compound can be determined by analyzing the electronic state by XPS. As an example of measurement conditions, the X-ray source is monochromatic AlKα, the X-ray beam diameter is 100 μmφ (25 W, 15 kV), the path energy is narrow scan: 58.70 eV, there is charge neutralization, and the number of sweeps is narrow scan: 10 times. (Carbon, oxygen) 20 times (fluorine) 30 times (phosphorus) 40 times (lithium element) 50 times (silicon), the energy step can be measured under the condition of narrow scan: 0.25 eV. It is preferable to clean the surface of the positive electrode by sputtering before measuring XPS. As the sputtering conditions, for example, the surface of the positive electrode can be cleaned under the condition 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).}
About the obtained XPS spectrum
The peak of the binding energy of Li1s of 50 to 54 eV is LiO ₂ or Li-C bond;
Peaks of 55-60 eV are LiF, Li ₂ CO ₃ , Li _x PO _y F _z (in the formula, x, y, z are integers 1 to 6);
C1s binding energy 285 eV peak is CC bond, 286 eV peak is CO bond, 288 eV peak is COO, 290-292 eV peak is CO ₃ ^2- , CF bond;
The peaks of the binding energy of O1s of 527 to 530 eV are O ^2- (Li ₂ O), and the peaks of 513 to 532 eV are CO, CO ₃ , OH, PO _x (x is an integer of 1 to 4 in the formula), SiO. _x (in the formula, x is an integer of 1 to 4), the peak of 533 eV is CO, SiO _x (in the formula, x is an integer of 1 to 4);
The peak of the binding energy of F1s of 685 eV is LiF, the peak of 687 eV is the CF bond, Li _x PO _y F _z (in the formula, x, y, z are integers of 1 to 6), PF ₆ ⁻ ;
Regarding the binding energy of P2p, the peak of 133 eV is PO _x (in the formula, x is an integer of 1 to 4), and the peak of 134 to 136 eV is PF _x (in the formula, x is an integer of 1 to 6);
The peak of binding energy 99eV of Si2p Si, silicide, a peak of 101~107eV _Si x _{O y} (wherein, x, y are arbitrary integers)
Can be attributed as.
When the peaks of the obtained spectrum overlap, it is preferable to separate the peaks assuming a Gaussian function or a Lorentz function and assign the spectra. The existing lithium compound can be identified from the obtained measurement result of the electronic state and the result of the presence element ratio.

[Ion chromatography]
By washing the positive electrode precursor with distilled water and analyzing the washed water by ion chromatography, carbonate ions eluted in water can be identified. As the column to be used, an ion exchange type, an ion exclusion type, and a reverse phase ion pair type can be used. As the detector, an electric conductivity detector, an ultraviolet-visible absorptiometric detector, an electrochemical detector, etc. can be used, and a suppressor method in which a suppressor is installed in front of the detector, or electricity without a suppressor. A non-suppressor method using a solution having low conductivity as an eluent can be used. It is also possible to measure by combining a mass spectrometer or a charged particle detector with a detector.

The retention time of the sample is constant for each ion species component if the conditions such as the column to be used and the eluent are determined, and the magnitude of the peak response differs for each ion species, but is proportional to the concentration of the ion species. .. By measuring in advance a standard solution having a known concentration that ensures traceability, it is possible to qualitatively and quantify the ionic species component.

<Method for quantifying alkali metal elements ICP-MS>
The positive electrode precursor is acid-decomposed with a strong acid such as concentrated nitric acid, concentrated hydrochloric acid, and aqua regia, and the obtained solution is diluted with pure water to an acid concentration of 2% to 3%. As for acid decomposition, it can be decomposed by heating and pressurizing as appropriate. The obtained diluted solution is analyzed by ICP-MS, and it is preferable to add a known amount of elements as an internal standard at this time. When the alkali metal element to be measured exceeds the upper limit concentration for measurement, it is preferable to further dilute the diluted solution while maintaining the acid concentration. With respect to the obtained measurement results, each element can be quantified based on a calibration curve prepared in advance using a standard solution for chemical analysis.

<Method for quantifying the amount of alkali metal compound and active substance Calculation of _{C x1} , _Cy1 and _Cx2 , _Cy2>
The method for quantifying the amount of the alkali metal compound and the active material contained in the positive electrode active material layer is described below. The non-aqueous lithium storage element is disassembled in an argon box to cut out a positive electrode, and the positive electrode is washed with an organic solvent. The organic solvent is not particularly limited as long as it can remove the electrolyte decomposition product deposited on the surface of the positive electrode, but elution of the alkali metal compound is suppressed by using an organic solvent having a solubility of the lithium compound of 2% or less. As such an organic solvent, for example, a polar solvent such as methanol, ethanol, acetone, or methyl acetate is preferably used. Although area measurement is positive is not particularly limited, it is preferably, more preferably 25 cm ² or more 150 cm ² or less from the viewpoint of reducing the variation in measurement is 5 cm ² or more 200 cm ² or less. If the area is 5 cm ² or more, the reproducibility of measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent.

The method for cleaning the positive electrode is to sufficiently immerse the positive electrode in an ethanol solution 50 to 100 times the weight of the positive electrode for 3 days or more. For example, it is preferable to cover the container so that ethanol does not volatilize during immersion. After soaking for 3 days or more, the positive electrode is taken out from ethanol and vacuum dried. The vacuum drying conditions are such that the residual ethanol in the positive electrode is 1% by mass or less in the range of temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, and time: 5 to 20 hours. The residual amount of ethanol can be quantified based on the calibration curve prepared in advance by measuring the GC / MS of the water after washing with distilled water, which will be described later. The obtained positive electrode is divided into a positive electrode central portion and a positive electrode outer peripheral portion according to the above definition, and the areas of the positive electrode central portion and the positive electrode outer peripheral portion are defined as S _x (m ² ) and S _y (m ² ), respectively. The weight of the outer peripheral portion of the positive electrode is M _0x (g) and M _0y (g), respectively. Subsequently, the central portion of the positive electrode and the outer peripheral portion of the positive electrode are sufficiently immersed in distilled water having a weight of 100 to 150 times the respective weights for 3 days or more. It is preferable to cover the container so that the distilled water does not volatilize during immersion. After soaking for 3 days or more, the central portion of the positive electrode and the outer peripheral portion of the positive electrode are taken out from the distilled water and vacuum dried in the same manner as the above ethanol washing. The weights of the central portion of the positive electrode and the outer peripheral portion of the positive electrode after vacuum drying are _defined as M 1x (g) and M _1y (g), respectively. Subsequently, in order to measure the weight of the obtained current collectors in the central portion of the positive electrode and the outer peripheral portion of the positive electrode, the positive electrode active material layer remaining in the central portion of the positive electrode and the outer peripheral portion of the positive electrode is removed using a spatula, a brush, a brush or the like. Assuming that the weights of the obtained positive electrode current collectors are M _2x (g) and M _2y (g), the amount of lithium compound C _{x 1} (g / m ² ) in the central portion of the positive electrode active material layer and the outer periphery of the positive electrode active material layer. The amount of lithium compound _Cy1 (g / m ² ) in the portion can be calculated by the formula (1).
C _x1 = (M _0x −M _1x ) / S _x , and _Cy1 = (M _0y −M _1y ) / S _y ... (1)
The positive active amount of active material in the central portion of the material layer _C x2 (g / ^{m 2)} and the positive electrode active amount of the active material of the outer peripheral portion of the material layer _C y2 (g / ^{m 2),} at the following equation (2) Can be calculated.
C _x2 = (M _1x −M _2x ) / S _x , and _Cy2 = (M _1y −M _2y ) / S _y ... (2)

When a plurality of lithium compounds are contained in the positive electrode active material layer; in addition to the lithium compound, M is M _{2 as one or more selected from Na, K, Rb, and Cs in the following formula.} Oxides such as O, hydroxides such as MOH, halides such as MF and _{MCl, oxalates such as M 2} (CO ₂ ) ₂ , RCOM (R is H, alkyl group, aryl group in the formula) when containing carboxylate and the like; as well as the positive electrode active material _{layer, BeCO 3, MgCO 3, CaCO} 3, SrCO 3, alkaline earth metal carbonate selected from BaCO _3, or alkaline earth metal oxides, alkaline earth When a metal hydroxide, an alkaline earth metal halide, an alkaline earth metal oxalate, or an alkaline earth metal carboxylate is contained, the total amount thereof is calculated as the amount of the alkali metal compound.
<Applications for non-aqueous lithium storage elements>
A storage module can be manufactured by connecting a plurality of non-aqueous lithium storage elements according to the present embodiment in series or in parallel. Further, since the non-aqueous lithium power storage element and the power storage module of the present embodiment can achieve both high input / output characteristics and safety at high temperature, a power regeneration assist system, a power load leveling system, and a power failure-free power supply system , Contactless power supply system, energy harvest system, power storage system, electric power steering system, emergency power supply system, in-wheel motor system, idling stop system, quick charging system, smart grid system, etc.
The power storage system is preferably used for natural power generation such as solar power generation or wind power generation, the power load leveling system is preferably used for microgrids, and the non-disruptive power supply system is preferably used for factory production equipment. In the non-contact power supply system, the non-aqueous lithium power storage element is used for leveling voltage fluctuations such as microwave power transmission or electric field resonance and for storing energy. Each is preferably used to use the generated power.
In a power storage system, a plurality of non-aqueous lithium storage elements are connected in series or in parallel as a cell stack, or a non-aqueous lithium storage element and a lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell. Are connected in series or in parallel.
Further, since the non-aqueous lithium power storage element according to the present embodiment can achieve both high input / output characteristics and safety at high temperature, for example, electric vehicles, plug-in hybrid vehicles, hybrid vehicles, electric motorcycles, etc. It can be mounted on a vehicle. The power regeneration assist system, the electric power steering system, the emergency power supply system, the in-wheel motor system, the idling stop system, or a combination thereof described above are preferably mounted on the vehicle.

Hereinafter, embodiments of the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples and Comparative Examples.

<Example 1>
<Preparation of positive electrode active material>
[Preparation Example 1a]
The crushed coconut shell carbide was placed in a small carbonization furnace and carbonized at 500 ° C. for 3 hours in a nitrogen atmosphere to obtain carbonized material. The obtained carbide was put into an activation furnace, steam heated in the preheating furnace was introduced into the activation furnace at 1 kg / h, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbon was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with water for 10 hours, drained, dried in an electric dryer maintained at 115 ° C. for 10 hours, and then pulverized with a ball mill for 1 hour to obtain activated carbon 1.
The average particle size of activated carbon 1 was measured using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation and found to be 4.2 μm. In addition, the pore distribution of activated carbon 1 was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 2360 m ² / g, the mesopore amount (V ₁ ) was 0.52 cc / g, the micro hole amount (V ₂ ) was 0.88 cc / g, and V ₁ / V ₂ = 0.59. there were.

[Preparation Example 2a]
The phenol resin was placed in a firing furnace and carbonized at 600 ° C. for 2 hours in a nitrogen atmosphere, then pulverized with a ball mill and classified to obtain a carbide having an average particle size of 7 μm. The obtained carbide and KOH were mixed at a mass ratio of 1: 5, placed in a firing furnace, and heated at 800 ° C. for 1 hour in a nitrogen atmosphere for activation. Activated carbon 2 was obtained by taking out the activated carbide, stirring and washing in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, boiling and washing with distilled water until the pH became stable between 5 and 6, and then drying.
As a result of measuring the average particle size of the activated carbon 2 using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation, it was 7.0 μm. In addition, the pore distribution of activated carbon 2 was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3627 m ² / g, the mesopore amount (V ₁ ) was 1.50 cc / g, the micro hole amount (V ₂ ) was 2.28 cc / g, and V ₁ / V ₂ = 0.66. there were.

<Crushing lithium carbonate>
200 g of lithium carbonate having an average particle size of 53 μm is cooled to -196 ° C. with liquid nitrogen using a crusher (liquid nitrogen bead mill LNM) manufactured by IMEX, and then using zirconia beads having a diameter of 1.0 mm, a peripheral speed of 10.0 m / The mixture was pulverized in s for 20 minutes to obtain lithium carbonate 1. By cooling to -196 ° C., brittle fracture can be achieved while preventing thermal denaturation of lithium carbonate. The average particle size of the obtained lithium carbonate 1 was measured and found to be 2.5 μm.

<Manufacturing of positive electrode precursor>
A positive electrode precursor was produced by using activated carbon 2 as a positive electrode active material and lithium carbonate 1 as an alkali metal compound.
Activated carbon 2 is 55.5 parts by mass, lithium carbonate 1 is 32.0 parts by mass, Ketjen black is 3.0 parts by mass, PVP (polypolypyrrolidone) is 1.5 parts by mass, and PVDF (polyvinylidene fluoride) is 8 parts. .0 parts by mass, and a mixed solvent of 99: 1 of NMP (N-methylpyrrolidone) and pure water were mixed, and the mixture was mixed at a peripheral speed of 17 m / s using a thin film swirling high-speed mixer fill mix manufactured by PRIMIX. The coating liquid was obtained by dispersing under the conditions of. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,750 mPa · s, and the TI value was 4.2. Moreover, the dispersity of the obtained coating liquid was measured using a grain gauge manufactured by Yoshimitsu Seiki Co., Ltd. As a result, the particle size was 31 μm. The coating liquid was applied to one or both sides of a 15 μm-thick aluminum foil using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, dried at a drying temperature of 120 ° C., and a positive electrode precursor. 1 (single side) and positive electrode precursor 1 (both sides) were obtained. The obtained positive electrode precursor 1 (single side) and positive electrode precursor 1 (both sides) were pressed with a roll press machine under the conditions of a pressure of 6 kN / cm and a surface temperature of the pressed portion of 25 ° C. The total thickness of the pressed positive electrode precursor 1 (single side) and positive electrode precursor 1 (both sides) was measured using a film thickness meter Liner Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd., for positive electrode precursor 1 (single side) and positive electrode precursor. Measurements were taken at any 10 locations on body 1 (both sides). The thickness of the aluminum foil was subtracted from the average value of the measured total thickness to determine the film thickness of the positive electrode active material layer of the positive electrode precursor 1 (one side) and the positive electrode precursor 1 (both sides). As a result, the film thickness of the positive electrode active material layer was 55 μm per one side.

<Preparation of negative electrode active material Preparation example 1>
The BET specific surface area and pore distribution of commercially available artificial graphite were measured by the method described above using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3.1 m ² / g, and the average particle size was 4.8 μm.

300 g of this artificial graphite is placed in a basket made of stainless steel mesh, placed on a stainless steel vat containing 30 g of coal-based pitch (softening point: 50 ° C.), and both are placed in an electric furnace (effective dimensions in the furnace 300 mm × 300 mm × 300 mm). ) Was installed. The artificial graphite and the carboniferous pitch were heated to 1000 ° C. in a nitrogen atmosphere in 12 hours and kept at the same temperature for 5 hours to cause a thermal reaction to obtain a composite porous carbon material 2a. The obtained composite porous carbon material 2a was cooled to 60 ° C. by natural cooling and taken out from an electric furnace.

The BET specific surface area and pore distribution of the obtained composite porous carbon material 2a were measured by the same method as described above. As a result, the BET specific surface area was 6.1 m ² / g and the average particle size was 4.9 μm. Further, in the composite porous carbon material 2a, the mass ratio of the carbonaceous material derived from the carbon-based pitch to the activated carbon was 2.0%.

<Manufacturing of negative electrode>
A negative electrode was manufactured using the composite porous carbon material 2a as the negative electrode active material.
84 parts by mass of composite porous carbon material 2a, 10 parts by mass of acetylene black, 6 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film manufactured by PRIMIX Corporation. Using a swirl-type high-speed mixer fill mix, a coating liquid was obtained by dispersing under the condition of a peripheral speed of 17 m / s. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,310 mPa · s, and the TI value was 2.9. The coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 2 m / s, and dried at a drying temperature of 120 ° C. to obtain a negative electrode 1. rice field. The obtained negative electrode 1 was pressed using a roll press machine under the conditions of a pressure of 5 kN / cm and a surface temperature of the pressed portion of 25 ° C. The total thickness of the pressed negative electrode 1 was measured at any 10 locations on the negative electrode 1 using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. The thickness of the negative electrode active material layer of the negative electrode 1 was obtained by subtracting the thickness of the copper foil from the average value of the measured total thickness. As a result, the film thickness of the negative electrode active material layer was 31 μm per one side.

[Measurement of capacity per unit weight of negative electrode]
One of the obtained negative electrode 1 was cut out to a size of 1.4 cm × 2.0 cm (2.8 cm ² ), and one layer of the negative electrode active material layer coated on both sides of the copper foil was a spatula, a brush, or a brush. It was removed with a brush to form a working electrode. _{LiPF 6} was dissolved at a concentration of 1.0 mol / L in a 1: 1 volume ratio mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) as an electrolytic solution using metallic lithium as a counter electrode and a reference electrode, respectively. Electrochemical cells were made in an argon box using a non-aqueous solution.
The initial charge capacity of the obtained electrochemical cell was measured by the following procedure using a charging / discharging device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd.
Against the electrochemical cell, at a temperature 25 ° C., after the voltage value at a current value 0.5 mA / cm ² was subjected to constant current charging until 0.01 V, further the current value reached 0.01 mA / cm ² Constant voltage charging was performed up to. When the charging capacity at the time of constant current charging and constant voltage charging was evaluated as the initial charging capacity, it was 0.74 mAh, and the capacity per unit mass of the negative electrode 1 (lithium ion doping amount) was 545 mAh / g. ..

<Preparation of electrolyte>
As an organic solvent, a mixed solvent of ethylene carbonate (EC): ethylmethyl carbonate (EMC) = 33: 67 (volume ratio) was used, and the concentration ratio of _{LiN (SO 2} F) ₂ and LiPF _{6 to the total electrolytic solution was} Each electrolyte salt is dissolved to obtain a non-aqueous electrolyte solution 1 so that the concentration is 75:25 (molar ratio) and _{the sum of the concentrations of LiN (SO 2} F) ₂ and LiPF _{6 is 1.2 mol / L.} rice field. _{The concentrations of LiN (SO 2} F) ₂ and LiPF ₆ in the non-aqueous electrolyte solution 1 were 0.9 mol / L and 0.3 mol / L, respectively.

<Manufacturing of non-aqueous lithium storage element>
^{The obtained positive electrode precursor 1 has two} positive electrode precursors 1 (one side) and one positive electrode precursor 1 (both sides) so that the positive electrode active material layer has a size of 10.0 cm × 10.0 cm (100 cm 2). Was cut out. Subsequently, 20 negative electrodes 1 were cut out so that the negative electrode active material layer had ^{a size of 10.1 cm × 10.1 cm (102 cm 2).} Further, 40 sheets of 10.3 cm × 10.3 cm (106 cm ² ) polyethylene separators (manufactured by Asahi Kasei Corporation, thickness 10 μm) were prepared. These are laminated so that the positive electrode precursor 1, the separator, and the negative electrode 1 are laminated in this order so that the positive electrode precursor 1 (one side) becomes the positive electrode precursor 1 (one side), and the positive electrode active material layer and the negative electrode active material layer face each other. An electrode laminate was obtained. The positive electrode terminal and the negative electrode terminal were ultrasonically welded to the obtained electrode laminate, placed in a container made of an aluminum laminate packaging material, and three sides including the electrode terminal portion were sealed by heat sealing.

About 70 g of the non-aqueous electrolyte solution 1 was injected into the electrode laminate housed in the aluminum laminate packaging material under atmospheric pressure, a temperature of 25 ° C., and a dew point of −40 ° C. or lower in a dry air environment. Subsequently, the aluminum laminate packaging material containing the electrode laminate and the non-aqueous electrolyte solution was placed in a decompression chamber, the pressure was reduced from atmospheric pressure to −87 kPa, the pressure was returned to atmospheric pressure, and the mixture was allowed to stand for 5 minutes. Then, the step of reducing the pressure of the packaging material in the chamber from atmospheric pressure to −87 kPa and then returning it to atmospheric pressure was repeated four times, and then the mixture was allowed to stand for 15 minutes. Further, the packaging material in the chamber was depressurized from atmospheric pressure to −91 kPa, and then returned to atmospheric pressure. Similarly, the steps of reducing the pressure and returning to the atmospheric pressure were repeated 7 times in total (the pressure was reduced from the atmospheric pressure to -95, -96, -97, -81, -97, -97, and -97 kPa, respectively). Through the above steps, the electrode laminate 1 was impregnated with the non-aqueous electrolyte solution 1.
After that, the electrode laminate impregnated with the non-aqueous electrolyte 1 was placed in a decompression sealer, and the aluminum laminate packaging material was sealed at 180 ° C. for 10 seconds at a pressure of 0.1 MPa in a state of being depressurized to −95 kPa. Sealed.

[Lithium dope process]
The electrode laminate obtained after sealing was placed in an argon box having a temperature of 25 ° C., a dew point of −60 ° C., and an oxygen concentration of 1 ppm. The excess portion of the aluminum laminate packaging material was cut and opened, and the central portion of the electrode laminate on the aluminum laminate was heated to 40 ° C. using a film heater of 6 cm × 6 cm. After that, using a power supply manufactured by Matsusada Precision Co., Ltd. (P4LT18-0.2), constant current charging was performed at a current value of 100 mA until the voltage reached 4.5 V, and then 4.5 V constant voltage charging was performed 72. Initial charging was performed by a time-continuous method, and the negative electrode was lithium-doped. After the lithium doping was completed, the aluminum laminate was sealed using a heat sealing machine (FA-300) manufactured by Fuji Impulse.

[Aging process]
The electrode laminate after lithium doping is taken out from the argon box, and a constant current discharge is performed at 100 mA at 100 mA until the voltage reaches 3.8 V in an environment of 25 ° C., and then a 3.8 V constant current discharge is performed for 1 hour to obtain a voltage. Was adjusted to 3.8V. Subsequently, the electrode laminate was stored in a constant temperature bath at 60 ° C. for 48 hours.

[Degassing process]
A part of the aluminum laminate packaging material was opened from the aged electrode laminate in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. Subsequently, the electrode laminate was placed in the decompression chamber, and the pressure was reduced from atmospheric pressure to -80 kPa for 3 minutes using a diaphragm pump (KNF, N816.3KT.45.18), and then over 3 minutes. The process of returning to atmospheric pressure was repeated a total of 3 times. After that, the electrode laminate was placed in a decompression sealing machine, the pressure was reduced to -90 kPa, and then the aluminum laminate packaging material was sealed by sealing at 200 ° C. for 10 seconds at a pressure of 0.1 MPa to form a non-aqueous lithium power storage element. Made. By the above steps, two non-aqueous lithium storage elements were manufactured.

<Evaluation of non-aqueous lithium storage element>
[Measurement of capacitance Fa]
For one of the obtained non-aqueous lithium storage elements, a current value of 2C was used in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Fukushima Limited. Constant current charging was performed at (1.6A) until it reached 3.8V, followed by constant voltage charging at which a constant voltage of 3.8V was applied for a total of 30 minutes. After that, the capacitance when constant current discharge is applied to a current value of 2C (1.6A) up to 2.2V is defined as Q [C], and the capacitance calculated by F = Q / (3.8-2.2). The capacity Fa was 1765F.

[Measurement of internal resistance Ra]
The non-aqueous lithium storage element obtained in the above step has a current value (16A) of 20C in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Fukushima Limited. ) Was charged with a constant current until it reached 3.8 V, and then constant voltage charging with a constant voltage of 3.8 V was performed for a total of 30 minutes. Then, the sampling time was set to 0.1 seconds, and constant current discharge was performed up to 2.2 V at a current value (16 A) of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time points of the discharge time of 2 seconds and 4 seconds is defined as Eo, the voltage drop ΔE = 3.8-Eo, and When the internal resistance Ra was calculated from R = ΔE / (current value 20C), it was 0.58 mΩ.

[High load charge / discharge cycle test]
The non-aqueous lithium storage element obtained in the above step has a current value (160A) of 200C using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited in a constant temperature bath set at 25 ° C. ), A constant current charge was performed until the current value reached 3.8 V, and then a constant current discharge was performed until the current value reached 2.2 V at 200 C. The charge / discharge process was repeated 60,000 times under the condition of no pause. When the internal resistance Rb was measured after the end of the cycle, it was 0.63 mΩ, and Rb / Ra = 1.09. Further, when the volume of the non-aqueous lithium storage element before and after the high load charge / discharge cycle was measured by the Archimedes method, the amount of gas generated was V = 1.4 cc.

<Quantification of lithium compounds and positive electrode active materials>
[Preparation of positive electrode sample]
The remaining non-aqueous lithium storage element was disassembled in an argon box with a dew point temperature of −72 ° C., and two positive electrodes coated with a positive electrode active material layer on both sides were cut out to a size of 10 cm × 10 cm to obtain the obtained material. Each of the positive electrodes was immersed in 150 g of diethyl carbonate solvent, and the positive electrodes were occasionally moved with tweezers to wash for 10 minutes. Subsequently, the positive electrode was taken out from the solvent, air-dried in an argon box for 5 minutes, the positive electrode was immersed in 150 g of newly prepared diethyl carbonate solvent, and washed for 10 minutes in the same manner as described above. The washed positive electrode was taken out from the argon box and dried using a vacuum dryer (manufactured by Yamato Scientific Co., Ltd., DP33) at a temperature of 25 ° C. and a pressure of 1 kPa for 20 hours to obtain two positive electrode samples 1.

[Calculation of _{C x1} , _Cy1 , C _x2 , _Cy2]
One of the positive electrode samples 1 was immersed in 150 g of an ethanol solvent, the container was covered, and the sample was allowed to stand in an environment of 25 ° C. for 3 days. Then, the positive electrode sample 1 was taken out and vacuum dried at 120 ° C. and 5 kPa for 10 hours. For the washed ethanol solution, GC / MS was measured under the condition that a calibration curve was prepared in advance, and it was confirmed that the abundance of diethyl carbonate was less than 1%. Thereafter, a positive electrode sample 1 was digested with 5mm position from the end of the four sides of the positive electrode active material layer, the positive electrode central portion (area _S x = 81cm ^2, the weight _M 0x = 0.836 g) and the cathode outer periphery (the area S _y = 19cm ^2, to obtain a weight _M 0y = 0.204g). The central portion of the positive electrode was impregnated with 83.6 g of distilled water and the outer peripheral portion of the positive electrode was impregnated with 20.4 g of distilled water, the container was covered, and the mixture was allowed to stand in an environment of 45 ° C. for 3 days. Then, the central portion of the positive electrode and the outer peripheral portion of the positive electrode were taken out and vacuum dried at 150 ° C. and 3 kPa for 12 hours. _{The weight M 1x of the} central portion of the positive electrode after vacuum drying was 0.783 g, and the weight M _{1y of the} outer peripheral portion of the positive electrode was 0.184 g. For the distilled water after washing, GC / MS was measured under the condition that a calibration curve was prepared in advance, and it was confirmed that the abundance of ethanol was less than 1%. Then, the active material layer on the positive electrode current collector was removed using a spatula, a brush, or a brush, and the weight of the positive electrode current collector was measured. As a result, M _2x = 0.321 g and M _2y = 0.075 g. rice field. According to the equations (1) and (2), C _x1 = 6.54, _Cy1 = 10.53, C _x2 = 57.04, and _Cy2 = 57.37 were calculated.

<A ₁ ,A ₂ Nosanshutsu_>
[Measurement of positive electrode surface SEM and EDX]
A small piece of 1 cm × 1 cm was cut out from the remaining positive electrode sample 1, and the surface was coated with gold by sputtering in a vacuum of 10 Pa. Subsequently, under the conditions shown below, SEM and EDX on the surface of the positive electrode were measured under atmospheric exposure.
(SEM-EDX measurement conditions)
-Measuring device: Electron emission scanning electron microscope FE-SEM S-4700 manufactured by Hitachi High-Technology
・ Acceleration voltage: 10kV
・ Emission current: 1μA
・ Measurement magnification: 2000 times ・ Electron beam incident angle: 90 °
・ X-ray extraction angle: 30 °
・ Dead time: 15%
-Mapping elements: C, O, F
-Number of measurement pixels: 256 x 256 pixels-Measurement time: 60 sec.
-Number of integrations: 50 times-The brightness and contrast were adjusted so that there were no pixels that reached the maximum brightness and the average value of the brightness was within the range of 40% to 60%.

(Analysis of SEM-EDX)
The obtained oxygen mapping and fluorine mapping were binarized based on the average value of brightness using image analysis software (ImageJ). The area of oxygen mapping at this time was 14.4% with respect to all images, and the area of fluorine mapping was 30.2%. The overlapping area of oxygen mapping and fluorine mapping obtained by binarization is 12.9% for all images, and if the area overlapping rate of fluorine mapping for oxygen mapping is A ₁ [%], A ₁ = 100. It was 89.6% from × 12.9 / 14.4.

[Measurement of positive electrode cross section SEM and EDX]
A small piece of 1 cm × 1 cm is cut out from the positive electrode sample 1, and a cross section perpendicular to the plane direction of the positive electrode sample 1 is formed under the conditions of an acceleration voltage of 4 kV and a beam diameter of 500 μm using SM-09020CP manufactured by JEOL Ltd. and argon gas. Made. Then, the positive electrode cross sections SEM and EDX were measured by the above-mentioned method.
For SEM-EDX of the obtained positive electrode section binarizes the oxygen mapping and fluorine mapping in the same manner as described above, was 42.2% when calculating the area overlapping ratio A ₂ fluorine mapping for oxygen mapping.

<Example 2>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 1 except that the negative electrode was lithium-doped.

<Example 3>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 1 except that the negative electrode was lithium-doped.

<Example 4>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 72 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 1 except that the negative electrode was lithium-doped.

<Example 5>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 4 except that the negative electrode was lithium-doped.

<Example 6>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 4 except that the negative electrode was lithium-doped.

<Example 7>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA, and then 4.3 V constant voltage charging is continued for 72 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 1 except that the negative electrode was lithium-doped.

<Example 8>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA, and then 4.3 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 7 except that the negative electrode was lithium-doped.

<Example 9>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA, and then 4.3 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 7 except that the negative electrode was lithium-doped.

<Example 10>
The same method as in Example 1 except that the central portion of the electrode laminate on the aluminum laminate was heated to 50 ° C. using a 6 cm × 6 cm film heater in the initial charging of the non-aqueous lithium storage element in the lithium doping step. A non-aqueous lithium storage element was manufactured in the above.

<Example 11>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 10 except that the negative electrode was lithium-doped.

<Example 12>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 10 except that the negative electrode was lithium-doped.

<Example 13>
The same method as in Example 1 except that the central portion of the electrode laminate on the aluminum laminate was heated to 60 ° C. using a 6 cm × 6 cm film heater in the initial charging of the non-aqueous lithium storage element in the lithium doping step. A non-aqueous lithium storage element was manufactured in the above.

<Example 14>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 13 except that the negative electrode was lithium-doped.

<Example 15>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Example 13 except that the negative electrode was lithium-doped.

<Comparative example 1>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, the central part of the electrode laminate on the aluminum laminate is not heated, and constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA. A non-aqueous lithium storage device was produced by the same method as in Example 1 except that the negative electrode was lithium-doped by continuing 4.5 V constant voltage charging for 72 hours.

<Comparative example 2>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 1 except that the negative electrode was lithium-doped.

<Comparative example 3>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 1 except that the negative electrode was lithium-doped.

<Comparative example 4>
In the initial charge of the non-aqueous lithium storage element in the lithium doping process, the central part of the electrode laminate on the aluminum laminate is not heated, and constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA. By continuing 4.6 V constant voltage charging for 72 hours, a non-aqueous lithium storage device was produced in the same manner as in Comparative Example 1 except that the negative electrode was lithium doped.

<Comparative example 5>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 4 except that the negative electrode was lithium-doped.

<Comparative Example 6>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.6 V at a current value of 100 mA, and then 4.6 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 4 except that the negative electrode was lithium-doped.

<Comparative Example 7>
In the initial charging of the non-aqueous lithium storage element in the lithium doping process, the central part of the electrode laminate on the aluminum laminate is not heated, and constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA. A non-aqueous lithium power storage device was manufactured in the same manner as in Comparative Example 1 except that the negative electrode was lithium-doped by continuing 4.3 V constant voltage charging for 72 hours.

<Comparative Example 8>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA, and then 4.3 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 7 except that the negative electrode was lithium-doped.

<Comparative Example 9>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.3 V at a current value of 100 mA, and then 4.3 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 7 except that the negative electrode was lithium-doped.

<Comparative Example 10>
The same method as in Example 1 except that the central portion of the electrode laminate on the aluminum laminate was heated to 80 ° C. using a 6 cm × 6 cm film heater in the initial charging of the non-aqueous lithium storage element in the lithium doping step. A non-aqueous lithium storage element was manufactured in the above.

<Comparative Example 11>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 10 except that the negative electrode was lithium-doped.

<Comparative Example 12>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 10 except that the negative electrode was lithium-doped.

<Comparative Example 13>
The same method as in Example 1 except that the central portion of the electrode laminate on the aluminum laminate was heated to 85 ° C. using a 6 cm × 6 cm film heater in the initial charging of the non-aqueous lithium storage element in the lithium doping step. A non-aqueous lithium storage element was manufactured in the above.

<Comparative Example 14>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 36 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 13 except that the negative electrode was lithium-doped.

<Comparative Example 15>
In the initial charge of the non-aqueous lithium storage element in the lithium doping step, constant current charging is performed until the voltage reaches 4.5 V at a current value of 100 mA, and then 4.5 V constant voltage charging is continued for 12 hours. A non-aqueous lithium storage device was produced in the same manner as in Comparative Example 13 except that the negative electrode was lithium-doped.

<Comparative Example 16>
Lithium carbonate was crushed in a 25 ° C environment using φ1.0 mm zirconia beads at a peripheral speed of 10.0 m / s for 5 minutes, and the coating liquid was prepared using 100% solvent of NMP (N-methylpyrrolidone). A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 10 except that it was used.

<Comparative example 17>
Lithium carbonate was crushed in a 25 ° C environment using φ1.0 mm zirconia beads at a peripheral speed of 10.0 m / s for 5 minutes, and the coating liquid was prepared using 100% solvent of NMP (N-methylpyrrolidone). A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 11 except that it was used.

<Comparative Example 18>
Lithium carbonate was crushed in a 25 ° C environment using φ1.0 mm zirconia beads at a peripheral speed of 10.0 m / s for 5 minutes, and the coating liquid was prepared using 100% solvent of NMP (N-methylpyrrolidone). A non-aqueous lithium storage element was produced in the same manner as in Comparative Example 12 except that it was used.

Table 1 shows the evaluation results of the non-aqueous lithium storage elements of Examples 1 to 15 and Comparative Examples 1 to 18.

<Example 16>
<Manufacturing of positive electrode precursor>
5. 0.5 parts by mass of activated carbon 1, 40.0 parts by mass of lithium carbonate, 3.0 parts by mass of Ketjen black, 1.5 parts by mass of PVP (polypolypyrrolidone), and PVDF (polyvinylidene fluoride). Positive electrode precursor 2 (one side) and positive electrode precursor 2 (both sides) in the same manner as in Example 1 except that 0 parts by mass and a mixed solvent of NMP (N-methylpyrrolidone) and pure water of 99: 1 were mixed. ) Was prepared.

<Preparation of negative electrode active material Preparation example 2>
The BET specific surface area and pore distribution of commercially available coconut shell activated carbon were measured by the method described above using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 1,790 m ² / g, the mesopore amount (V ₁ ) was 0.199 cc / g, the micropore amount (V ₂ ) was 0.698 cc / g, and V ₁ / V ₂ = 0. 29, and the average pore size was 20.1 Å.
300 g of this coconut shell activated carbon is placed in a basket made of stainless steel mesh, placed on a stainless steel bat containing 540 g of coal-based pitch (softening point: 50 ° C.), and both are placed in an electric furnace (effective dimensions in the furnace: 300 mm × 300 mm ×). It was installed within 300 mm). The temperature of the coconut shell activated carbon and the coal-based pitch was raised to 600 ° C. in 8 hours under a nitrogen atmosphere, and the temperature was maintained at the same temperature for 4 hours to cause a thermal reaction to obtain a composite porous carbon material 1b. The obtained composite porous carbon material 1b was cooled to 60 ° C. by natural cooling, and then taken out from an electric furnace.
The BET specific surface area and pore distribution of the obtained composite porous carbon material 1b were measured by the same method as described above. As a result, the BET specific surface area was 262 m ² / g, the mesopore amount (V _m1 ) was 0.186 cc / g, the micropore amount (V _m2 ) was 0.082 cc / g, and V _m1 / V _m2 = 2.27. there were. Further, in the composite porous carbon material 1b, the mass ratio of the carbonaceous material derived from the coal-based pitch to the activated carbon was 78%.

<Manufacturing of negative electrode>
A negative electrode was manufactured using the composite porous carbon material 1b as a negative electrode active material.
84 parts by mass of composite porous carbon material 1b, 10 parts by mass of acetylene black, 6 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed, and the mixture is a thin film manufactured by PRIMIX Corporation. Using a swirl-type high-speed mixer fill mix, a coating liquid was obtained by dispersing under the condition of a peripheral speed of 17 m / s. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. As a result, the viscosity (ηb) was 2,789 mPa · s, and the TI value was 4.3. The coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 2 m / s, and dried at a drying temperature of 120 ° C. to obtain a negative electrode 2. Obtained. The obtained negative electrode 2 was pressed using a roll press machine under the conditions of a pressure of 5 kN / cm and a surface temperature of the pressed portion of 25 ° C. The total thickness of the pressed negative electrode 2 was measured at any 10 locations on the negative electrode 2 using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. The thickness of the negative electrode active material layer of the negative electrode 2 was obtained by subtracting the thickness of the copper foil from the average value of the measured total thickness. As a result, the film thickness of the negative electrode active material layer was 40 μm per one side.

[Measurement of capacity per unit weight of negative electrode]
One of the obtained negative electrode 2 was cut out to a size of 1.4 cm × 2.0 cm (2.8 cm ² ), and one layer of the negative electrode active material layer coated on both sides of the copper foil was a spatula, a brush, or a brush. It was removed with a brush to form a working electrode. _{LiPF 6} was dissolved at a concentration of 1.0 mol / L in a 1: 1 volume ratio mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) as an electrolytic solution using metallic lithium as a counter electrode and a reference electrode, respectively. Electrochemical cells were made in an argon box using a non-aqueous solution.
The initial charge capacity of the obtained electrochemical cell was measured by the following procedure using a charging / discharging device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd.
Against the electrochemical cell, at a temperature 25 ° C., after the voltage value at a current value 0.5 mA / cm ² was subjected to constant current charging until 0.01 V, further the current value reached 0.01 mA / cm ² Constant voltage charging was performed up to. When the charging capacity at the time of constant current charging and constant voltage charging was evaluated as the initial charging capacity, it was 1.6 mAh, and the capacity per unit mass of the negative electrode 2 (lithium ion doping amount) was 1460 mAh / g. ..

<Manufacturing and evaluation of non-aqueous lithium metal storage elements>
A non-aqueous lithium metal storage element was produced in the same manner as in Example 1 except that two positive electrode precursors 2 (single side), 19 positive electrode precursors 2 (both sides), and 20 negative electrode 2s were used. ,evaluated.

<Example 17>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 36 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Example 16 except that the negative electrode was lithium-doped.

<Example 18>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 12 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Example 16 except that the negative electrode was lithium-doped.

<Comparative Example 19>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging was performed until the voltage reached 4.5 V at a current value of 100 mA without heating the central portion of the electrode laminate on the aluminum laminate. After that, by continuing 4.5 V constant voltage charging for 72 hours, a non-aqueous lithium metal-type power storage element was produced in the same manner as in Example 16 except that the negative electrode was lithium-doped.

<Comparative Example 20>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 36 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Comparative Example 19 except that the negative electrode was lithium-doped.

<Comparative Example 21>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 12 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Comparative Example 19 except that the negative electrode was lithium-doped.

<Example 19>
A non-aqueous lithium metal storage device was produced in the same manner as in Example 16 except that sodium carbonate was used as the alkali metal compound.

<Example 20>
A non-aqueous lithium metal storage device was produced in the same manner as in Example 16 except that potassium carbonate was used as the alkali metal compound.

<Example 21>
A non-aqueous lithium metal storage device was produced in the same manner as in Example 16 except that cesium carbonate was used as the alkali metal compound.

<Comparative Example 22>
A non-aqueous lithium metal storage device was produced in the same manner as in Comparative Example 19 except that sodium carbonate was used as the alkali metal compound.

<Comparative Example 23>
A non-aqueous lithium metal storage device was produced in the same manner as in Comparative Example 19 except that potassium carbonate was used as the alkali metal compound.

<Comparative Example 24>
A non-aqueous lithium metal storage device was produced in the same manner as in Comparative Example 19 except that cesium carbonate was used as the alkali metal compound.

<Example 22>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of lithium carbonate and sodium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Example 23>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of lithium carbonate and potassium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Example 24>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of sodium carbonate and potassium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Example 25>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of lithium carbonate and lithium oxide having a weight ratio of 75:25 was used as the alkali metal compound.

<Example 26>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of lithium carbonate and lithium hydroxide having a weight ratio of 75:25 was used as the alkali metal compound.

<Example 27>
A non-aqueous lithium metal power storage element was produced in the same manner as in Example 16 except that a mixture of sodium carbonate and calcium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 28>
A non-aqueous lithium metal storage element was produced in the same manner as in Comparative Example 19 except that a mixture of lithium carbonate and sodium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 29>
A non-aqueous lithium metal power storage element was produced in the same manner as in Comparative Example 19 except that a mixture of lithium carbonate and potassium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 30>
A non-aqueous lithium metal power storage element was produced in the same manner as in Comparative Example 19 except that a mixture of sodium carbonate and potassium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 31>
A non-aqueous lithium metal storage element was produced in the same manner as in Comparative Example 19 except that a mixture of lithium carbonate and lithium oxide having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 32>
A non-aqueous lithium metal power storage element was produced in the same manner as in Comparative Example 19 except that a mixture of lithium carbonate and lithium hydroxide having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 33>
A non-aqueous lithium metal power storage element was produced in the same manner as in Comparative Example 19 except that a mixture of sodium carbonate and calcium carbonate having a weight ratio of 75:25 was used as the alkali metal compound.

<Comparative Example 34>
In the step of producing the positive electrode precursor, the coating liquid was applied using a concave die having a clearance between the die and the positive electrode current collector of 240 μm at the center and 200 μm at the end, in the same manner as in Example 16. A non-aqueous lithium metal type current collector was manufactured.

<Comparative Example 35>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 36 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Comparative Example 34 except that the negative electrode was lithium-doped.

<Comparative Example 36>
In the step of producing the positive electrode precursor, the coating liquid was applied using a concave die having a clearance between the die and the positive electrode current collector of 260 μm at the center and 180 μm at the end, in the same manner as in Example 16. A non-aqueous lithium metal type current collector was manufactured.

<Comparative Example 37>
In the initial charging of the non-aqueous lithium metal storage element in the lithium doping process, constant current charging is performed until the voltage reaches 4.5V at a current value of 100mA, and then 4.5V constant voltage charging is continued for 36 hours. A non-aqueous lithium metal-type power storage element was produced in the same manner as in Comparative Example 36 except that the negative electrode was lithium-doped.

Table 2 shows the evaluation results of the non-aqueous lithium metal-type power storage elements of Examples 16 to 27 and Comparative Examples 19 to 37.

The following facts are clear from Tables 1 and 2:
_{When the ratio C x1} / _Cy1 of the lithium compound in the central portion of the positive electrode active material layer to the lithium compound in the outer peripheral portion is 0.50 or more and 0.96 or less, the non-aqueous lithium storage element can be used in a high load charge / discharge cycle. It was possible to suppress the generation of gas when heat was generated, and it was possible to suppress the increase in resistance. On the other hand, if C _x1 / _{Cy1 is set} to less than 0.50, fluorine ions generated during the high load charge / discharge cycle cannot be sufficiently captured, so that gas is generated and the resistance increases.

Further, it is considered that by pulverizing the alkali metal compound under the extremely low temperature condition of -196 ° C., it was possible to suppress the formation of defects on the surface of the alkali metal compound particles without being affected by the temperature rise during pulverization. As a result, it is considered that the reaggregation of the alkali metal compound could be suppressed. Furthermore, by adding a small amount of water when preparing the coating liquid, the surface of the alkali metal compound is activated, and LiPF _6, which is an electrolyte, can be efficiently decomposed on the surface of the alkali metal compound particles, resulting in the result. It is considered that the generated fluorine compounds were evenly deposited, and the high temperature storage characteristics and the high load charge / discharge characteristics were improved.

The non-aqueous lithium storage element of the present invention can be suitably used as a power storage element in, for example, an automobile hybrid drive system for assisting an instantaneous power peak.
The non-aqueous lithium storage element of the present invention is preferable because the effect of the present invention is maximized when applied as, for example, a lithium ion capacitor or a lithium ion secondary battery.

1 Positive electrode terminal 2 Positive electrode active material layer 3 Central part of positive electrode active material layer 4 Outer peripheral part of positive electrode active material layer 5 Negative electrode terminal 6 Electrode laminate 7 Exterior

Claims (29)

Positive electrode containing alkali metal compounds other than active material,
Negative electrode,
Separator, and non-aqueous electrolyte solution containing lithium ions,
It is a non-aqueous lithium storage element containing
A positive electrode active material layer composed of the active material and the alkali metal compound is coated on the positive electrode current collector of the positive electrode, and the amount of the alkali metal compound in the central portion of the positive electrode active material layer is C _{x 1} (g / m). The ratio C _x1 / _{Cy1 of} ² ) and the amount of alkali metal compound _Cy1 (g / m ² ) on the outer peripheral portion is 0.50 or more and 0.96 or less.
Non-aqueous lithium storage element. Wherein the ratio _C x2 _{/ C y2} of the active material of the central portion of the positive electrode active material layer _C x2 (g / ^{m 2)} and the active material amount of the outer peripheral portion _C y2 (g / ^{m 2)} is 0.85 or more The non-aqueous lithium storage element according to claim 1, which is 1.15 or less. In the element mapping obtained by scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX) on the surface of the positive electrode, the area overlap rate A of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness. The non-aqueous lithium storage element according to claim 1 or 2, wherein _{1 is 40% or more and 99% or less.} In the element mapping obtained by SEM-EDX of the cross section of the positive electrode processed by broad ion beam (BIB), the area overlap rate A ₂ of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is 10%. The non-aqueous lithium storage element according to any one of claims 1 to 3, which is 60% or less. The non-aqueous lithium power storage element according to any one of claims 1 to 4, wherein the alkali metal compound is lithium carbonate, lithium oxide, or lithium hydroxide. The positive electrode active material layer is provided on one side or both sides of the positive electrode current collector.
The amount of mesopores derived from the pores of the positive electrode active material contained in the positive electrode active material layer 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 diameter is less than 20 Å calculated by the MP method. When the amount of micropores derived from the pores is V ₂ (cc / g), 0.3 <V ₁ ≤ 0.8 and 0.5 ≤ V ₂ ≤ 1.0 are satisfied, and the BET method is used. Activated carbon having a measured specific surface area of 1,500 m ² / g or more and 3,000 m ² / g or less.
The non-aqueous lithium storage element according to any one of claims 1 to 5. _{The positive electrode active material contained in the positive electrode active material layer has a mesopore amount V 1} (cc / g) of 0.8 <V ₁ ≤ 2.5 derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method. _{, And the micropore amount V 2} (cc / g) derived from pores with a diameter of less than 20 Å calculated by the MP method satisfies _{0.8 <V 2} ≤ 3.0, and the ratio measured by the BET method. The non-aqueous lithium storage element according to any one of claims 1 to 5, which is an activated carbon having a surface area of 2,300 m ² / g or more and 4,000 m ^{2 / g or less.} The item according to any one of claims 1 to 7, wherein the doping amount of lithium ion with respect to the negative electrode active material contained in the negative electrode is 530 mAh / g or more and 2,500 mAh / g or less per unit mass of the negative electrode active material. Non-aqueous lithium storage element. The non-aqueous lithium storage element according to claim 8, wherein the negative electrode active material has a BET specific surface area of 100 m ² / g or more and 1,500 m ^{2 / g or less.} The non-aqueous system according to any one of claims 1 to 7, wherein the amount of lithium ions doped into the negative electrode active material contained in the negative electrode is 50 mAh / g or more and 700 mAh / g or less per unit mass of the negative electrode active material. Lithium storage element. The non-aqueous lithium storage element according to claim 10, wherein the negative electrode active material has a BET specific surface area of 1 m ² / g or more and 50 m ^{2 / g or less.} The non-aqueous lithium storage element according to any one of claims 8 to 11, wherein the average particle size of the negative electrode active material is 1 μm or more and 10 μm or less. A power storage module including the non-aqueous lithium power storage element according to any one of claims 1 to 12. A power regeneration assist system including the non-aqueous lithium storage element according to any one of claims 1 to 12. A power load leveling system including the non-aqueous lithium storage element according to any one of claims 1 to 12. An uninterruptible power supply system including the non-aqueous lithium storage element according to any one of claims 1 to 12. A non-contact power supply system including the non-aqueous lithium storage element according to any one of claims 1 to 12. An energy harvesting system including the non-aqueous lithium storage element according to any one of claims 1 to 12. A power storage system including the non-aqueous lithium power storage element according to any one of claims 1 to 12. A power storage system in which the non-aqueous lithium power storage element according to any one of claims 1 to 12 and a lead battery, a nickel hydrogen battery, a lithium ion secondary battery or a fuel cell are connected in series or in parallel. A photovoltaic power storage system including the non-aqueous lithium power storage element according to any one of claims 1 to 12. An electric power steering system including the non-aqueous lithium storage element according to any one of claims 1 to 12. An emergency power supply system including the non-aqueous lithium storage element according to any one of claims 1 to 12. An in-wheel motor system including the non-aqueous lithium storage element according to any one of claims 1 to 12. An idling stop system including the non-aqueous lithium storage element according to any one of claims 1 to 12. A vehicle including the non-aqueous lithium storage element according to any one of claims 1 to 12. The vehicle according to claim 26, which is an electric vehicle, a plug-in hybrid vehicle, a hybrid vehicle, or an electric motorcycle. A quick charging system including the non-aqueous lithium storage element according to any one of claims 1 to 12. A smart grid system including the non-aqueous lithium storage element according to any one of claims 1 to 12.

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