CN107925038A - Non-aqueous secondary battery functional layer composition, non-aqueous secondary battery functional layer and non-aqueous secondary battery - Google Patents

Abstract

The object of this invention is to provide the composition for nonaqueous secondary battery functional layers which can improve the electrical characteristic of a secondary battery. The non-aqueous secondary battery functional layer composition of the present invention comprises inorganic substances, and the inorganic substances are obtained by X-ray diffraction method, in the X-ray diffraction pattern with the diffraction intensity as the vertical axis and the diffraction angle 2θ as the horizontal axis. When the total integral of the above-mentioned diffraction intensity at the diffraction angle 2θ=3° to 90° is 100%, the interplanar distance corresponding to 2θ at the position where the above-mentioned diffraction intensity integrated from the high diffraction angle side becomes 50% of the above-mentioned total integral It is not less than 0.1 nm and not more than 0.4 nm, and the interplanar distance corresponding to the 2θ of the 80% position is not less than 0.15 nm and not more than 0.70 nm.

Description

Composition for functional layer of nonaqueous secondary battery, functional layer for nonaqueous secondary battery and non-aqueous secondary batteries

technical field

The present invention relates to a composition for a functional layer of a nonaqueous secondary battery, a functional layer for a nonaqueous secondary battery, and a nonaqueous secondary battery, in particular to a composition for a functional layer of a nonaqueous secondary battery containing inorganic substances, a nonaqueous secondary battery Functional layer for batteries and non-aqueous secondary batteries.

Background technique

Non-aqueous secondary batteries such as lithium ion secondary batteries (hereinafter, sometimes simply referred to as "secondary batteries") are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are used in a wide range of applications. Furthermore, a non-aqueous secondary battery generally has battery components such as a positive electrode, a negative electrode, and a separator for isolating the positive electrode and the negative electrode to prevent a short circuit between the positive electrode and the negative electrode.

Here, in the secondary battery, a battery member having a functional layer that imparts desired performance to the battery member is used. Specifically, for example, a separator in which a functional layer is formed on a separator base material and an electrode in which a functional layer is formed on an electrode base material in which an electrode composite material layer is provided on a current collector are used as battery members. .

In addition, in recent years, improvement of functional layers has become increasingly popular for the purpose of further enhancing the performance of secondary batteries. For example, an electrode is proposed in which a functional layer capable of trapping moisture and hydrogen fluoride (HF) is formed on an electrode substrate (see, for example, Patent Document 1). The functional layer described in Patent Document 1 contains inorganic particles having a predetermined BET specific surface area, and the inorganic particles trap moisture and hydrogen fluoride in the secondary battery, thereby improving the rate characteristics and cycle characteristics of the secondary battery.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2011-210413.

Contents of the invention

The problem to be solved by the invention

However, in recent years, the performance of secondary batteries has been further improved, and there is room for improvement in the electrical characteristics (such as high-temperature cycle characteristics and low-temperature output characteristics) of secondary batteries having the functional layers described in Patent Document 1. In particular, in recent years, from the viewpoint of increasing the capacity, positive electrode active materials containing transition metals have sometimes been used in secondary batteries. However, in secondary batteries, there is a risk that transition metals are eluted from the positive electrode active material due to hydrogen fluoride generated in the battery, and the eluted transition metals are deposited on the negative electrode, thereby degrading the electrical characteristics of the secondary battery.

Then, the object of this invention is to provide the composition for nonaqueous secondary battery functional layers which can improve the electrical characteristic of a secondary battery. Furthermore, an object of the present invention is to provide a functional layer for a non-aqueous secondary battery capable of improving the electrical characteristics of the secondary battery. Another object of the present invention is to provide a non-aqueous secondary battery using the functional layer for a non-aqueous secondary battery and having favorable electrical characteristics.

solutions to problems

The inventors of the present invention conducted intensive studies for the purpose of solving the above problems. Then, the present inventors found that the electrical characteristics of a secondary battery can be improved by blending an inorganic substance having predetermined properties into a functional layer composition for a secondary battery, and completed the present invention.

That is, the object of the present invention is to advantageously solve the above-mentioned problems, and the composition for the functional layer of the non-aqueous secondary battery of the present invention is characterized in that it contains inorganic substances, and the above-mentioned inorganic substances are obtained by X-ray diffraction method, and the diffraction intensity is In the X-ray diffraction pattern with the vertical axis and the diffraction angle 2θ on the horizontal axis, when the total integral (cumulative accumulation) of the above-mentioned diffraction intensity at the diffraction angle 2θ=3° to 90° is set to 100%, the X-ray diffraction pattern is compared with that from the high diffraction angle side The integrated integral of the above-mentioned diffraction intensity is 50% of the above-mentioned total integral, and the interplanar distance corresponding to 2θ is 0.1 nm to 0.4 nm, and the interplanar distance corresponding to 2θ at 80% of the position is 0.15 nm to 0.70 nm the following. The electrical characteristics of a secondary battery can be improved by using the functional layer formed using the composition for nonaqueous secondary battery functional layers containing such an inorganic substance.

Here, in the present invention, the X-ray diffraction spectrum of the inorganic substance can be obtained by X-ray diffraction at a measurement temperature of 25°C and using Cu-Kα rays as the X-ray source.

Here, in the composition for a non-aqueous secondary battery functional layer of the present invention, it is preferable that the ratio of the above-mentioned inorganic substance to the total solid content is 85% by mass or more. The electrical characteristics of a secondary battery can be improved by the functional layer formed using this composition for functional layers.

In addition, in the composition for a non-aqueous secondary battery functional layer of the present invention, it is preferable that the above-mentioned inorganic substance is hydrotalcite and/or zeolite. This is because, by forming a functional layer using a composition for a functional layer containing hydrotalcite and zeolite, the high-temperature cycle characteristics of a secondary battery having the functional layer can be further improved.

Furthermore, the object of the present invention is to advantageously solve the above-mentioned problems, and the functional layer for a non-aqueous secondary battery of the present invention is characterized in that it is formed using any one of the above-mentioned compositions for a non-aqueous secondary battery functional layer. Such a functional layer enables a secondary battery having the functional layer to exhibit excellent low-temperature output characteristics and high-temperature cycle characteristics.

Furthermore, the present invention aims to advantageously solve the above-mentioned problems, and the non-aqueous secondary battery of the present invention is characterized by having the above-mentioned functional layer for a non-aqueous secondary battery. Such a non-aqueous secondary battery is excellent in low-temperature output characteristics and high-temperature cycle characteristics.

Here, the non-aqueous secondary battery of the present invention has a positive electrode, a negative electrode, an electrolytic solution, and a separator, and the separator preferably has the above-mentioned functional layer for a non-aqueous secondary battery. This is because the electrical characteristics of the secondary battery can be further improved by using the separator having the above-mentioned functional layer.

Here, in the nonaqueous secondary battery of the present invention, it is preferable that the positive electrode includes a positive electrode active material containing any one or more of Co, Mn, Fe, and Ni. In the secondary battery having the above-mentioned functional layer, even in the case of using a positive electrode active material having any of Co, Mn, Fe, and Ni, it is possible to sufficiently suppress the leaching of Co, Mn, Fe, and Ni, etc. The electrical characteristics of the secondary battery are degraded.

Invention effect

According to this invention, the composition for nonaqueous secondary battery functional layers which can improve the electrical characteristic of a secondary battery can be provided. Moreover, according to this invention, the functional layer for nonaqueous secondary batteries which can improve the electrical characteristic of a secondary battery can be provided. Furthermore, according to the present invention, a non-aqueous secondary battery having excellent electrical characteristics can be provided.

Detailed ways

Embodiments of the present invention will be described in detail below.

Here, the composition for a nonaqueous secondary battery functional layer of the present invention can be used as a material when producing the functional layer for a nonaqueous secondary battery of the present invention. And the functional layer for nonaqueous secondary batteries of this invention is formed using the composition for nonaqueous secondary battery functional layers of this invention. Moreover, the nonaqueous secondary battery of this invention has the functional layer for nonaqueous secondary batteries of this invention at least.

(Composition for functional layer of non-aqueous secondary battery)

The composition for a non-aqueous secondary battery functional layer of the present invention is a slurry composition containing an inorganic substance and an optional binder, and using an organic solvent or the like as a dispersion medium. Specifically, the composition for the functional layer of the non-aqueous secondary battery of the present invention is characterized in that it contains inorganic substances. In the X-ray diffraction pattern of , when the total integral of the above-mentioned diffraction intensity at the diffraction angle 2θ=3° to 90° is set as 100%, the integral with the diffraction intensity integrated from the high diffraction angle side is 50% of the total integral The interplanar spacing corresponding to 2θ of the positions is 0.1 nm to 0.4 nm, and the interplanar spacing corresponding to 2θ of 80% of the positions is 0.15 nm to 0.7 nm.

And, because the composition for non-aqueous secondary battery functional layer of the present invention satisfies the above-mentioned condition due to the interplanetary distance between crystal planes in the crystal structure of the inorganic substance, it is possible to make The electrical characteristics of the secondary battery of the formed functional layer are improved.

Here, the reason why the electrical characteristics of the secondary battery can be improved by using the composition for a non-aqueous secondary battery functional layer containing the above-mentioned inorganic substance is not clear, but it is presumed to be as follows. That is, in a secondary battery, especially in a secondary battery using a positive electrode active material containing a transition metal, the transition is usually caused by hydrogen fluoride (hereinafter also referred to as "hydrofluoric acid") generated in the secondary battery. Metals such as metals are eluted from the positive electrode active material to generate metal ions such as transition metal ions. Furthermore, when the generated metal ions move through the electrolyte solution and reach the negative electrode, they are reduced and precipitated at the negative electrode. Furthermore, metal ions react with an electrolytic solution containing carbonates such as ethylene carbonate to generate gases such as carbon monoxide and carbon dioxide, deteriorating the electrical characteristics of the secondary battery. However, an inorganic substance having the aforementioned predetermined crystal structure can efficiently trap metal ions such as transition metal ions in the gaps between crystal planes in the crystal structure, and it is difficult to release the trapped metal ions. Furthermore, the above-mentioned inorganic substance captures metal ions such as transition metal ions, and does not easily hinder the movement of ions contributing to battery reactions in the secondary battery. In addition, "ions that contribute to battery reaction" are generally monovalent ions, and are lithium ions (Li ⁺ ) when the secondary battery is a lithium ion secondary battery, for example. By forming a functional layer using the composition for a non-aqueous secondary battery functional layer containing the above-mentioned inorganic substance in this way, metal ions generated at the positive electrode can be captured before reaching the negative electrode, and gas generation in the secondary battery can be suppressed. Therefore, the electrical characteristics of the secondary battery such as high-temperature cycle characteristics and low-temperature output characteristics can be improved.

<Inorganic matter>

—Crystal Structure of Inorganic Substances—

Here, the above-mentioned inorganic substances mixed in the composition for the functional layer of the non-aqueous secondary battery need to be obtained by the X-ray diffraction method. In the X-ray diffraction pattern with the diffraction intensity as the vertical axis and the diffraction angle 2θ as the horizontal axis, When the total integral of the above-mentioned diffraction intensity in the range of diffraction angle 2θ = 3° to 90° is taken as 100%, the surface corresponding to 2θ at the position where the integral of the diffraction intensity accumulated from the high diffraction angle side is 50% of the total integral The pitch is not less than 0.10 nm and not more than 0.40 nm, preferably not less than 0.12 nm, more preferably not less than 0.15 nm, preferably not more than 0.30 nm, more preferably not more than 0.25 nm. If, in the diffraction pattern obtained by the X-ray diffraction method, the interplanar distance corresponding to 2θ at the position where the integral of the diffraction intensity accumulated from the high diffraction angle side (i.e., the narrow side of the interplanar distance) is 50% of the total integral is 0.10 nm Above, metal ions such as transition metal ions (metal ions from the positive electrode active material) are easy to enter the crystal structure of the inorganic matter, and the amount of metal captured in the inorganic matter can be increased, so the high-temperature cycle characteristics of the secondary battery can be improved. improve. In addition, if in the diffraction pattern obtained by the X-ray diffraction method, the interplanar distance corresponding to 2θ at the position where the integral of the diffraction intensity accumulated from the high diffraction angle side is 50% of the total integral is 0.40 nm or less, the captured metal Ions are not easy to detach from the crystal structure of inorganic substances, the amount of metal capture increases, and it can inhibit the particles that contribute to the battery reaction from being captured to the detachment of the captured metal ions (that is, the movement of ions that contribute to the battery reaction is hindered) conditions), so that the low-temperature output characteristics and high-temperature cycle characteristics of the secondary battery can be improved.

Furthermore, in the diffraction pattern obtained by the X-ray diffraction method, the above-mentioned inorganic substance needs to have an interplanar distance of 0.15 nm or more and 0.70 nm or more corresponding to the 2θ of the position where the integration of the diffraction intensity accumulated from the high diffraction angle side is 80% of the total integration. nm or less, preferably 0.16 nm or more, more preferably 0.18 nm or more, preferably 0.60 nm or less, more preferably 0.50 nm or less. In addition, the interplanar distance corresponding to 2θ at the 80% position is larger than the interplanar distance corresponding to 2θ at the 50% position. If, in the diffraction pattern obtained by the X-ray diffraction method, the interplanar distance corresponding to 2θ at the position where the integral of the diffraction intensity accumulated from the high diffraction angle side (that is, the narrow side of the interplanar distance side) is 80% of the total integral is 0.15 nm Above, then can reduce the ratio of the crystalline part (part with small interplanar distance) that has a smaller ionic radius and is easy to capture ions that contribute to the battery reaction, and suppress the ions that contribute to the battery reaction from being captured in the crystal structure, making the secondary The output characteristics of the battery are improved. In addition, in the diffraction pattern obtained by the X-ray diffraction method, if the interplanar distance corresponding to the 2θ of the position where the integral of the diffraction intensity accumulated from the high diffraction angle side is 80% of the total integral is 0.70 nm or less, it is captured Metal ions in the crystal structure of the inorganic substance are less likely to escape from the crystal structure, and the amount of metal capture can be increased, thereby improving the cycle characteristics of the secondary battery.

Here, the "X-ray diffraction pattern" of the inorganic particles in the composition is the same as the diffraction pattern obtained by performing X-ray diffraction on the inorganic particles which are materials blended in the composition.

Also, the inorganic substance is preferably an inorganic compound having a layered structure. Here, the layered structure refers to, for example, a structure in which atoms are arranged in a plane shape and is formed by laminating multiple layers. By blending an inorganic substance having a layered structure with interplanar distances within a specific range in the composition for a non-aqueous secondary battery functional layer, transition metal ions can be well captured between layers. Therefore, a secondary battery excellent in electrical characteristics can be provided.

—Conductivity of Inorganic Substances—

In addition, inorganic substances are generally non-conductive, and specifically, the volume resistivity (Ω·cm) is preferably 10 ⁵ or more, more preferably 10 ¹⁰ or more.

—Volume average particle size of inorganic substances—

In addition, the volume average particle diameter of the inorganic substance is preferably 0.1 μm or more, more preferably 0.2 μm or more, preferably 5.0 μm or less, more preferably 3.0 μm or less. If the volume-average particle diameter of the inorganic substance is 0.1 μm or more, the amount of moisture brought into the functional layer formed using the functional layer composition of the present invention can be reduced, and the high-temperature cycle characteristics of the secondary battery having the functional layer can be further improved. . In addition, if the volume average particle diameter of the inorganic substance is 5.0 μm or less, the thickness of the functional layer formed using the composition for the functional layer of the non-aqueous secondary battery of the present invention can be suppressed from increasing and the volume resistance of the functional layer increases, To improve the low-temperature output characteristics of a secondary battery having a functional layer.

—Types of Inorganic Substances—

For example, the inorganics may be layered double hydroxides or zeolites. Examples of layered double hydroxides include hydrotalcite, motukoreaite, manasseite, stichtite, and motukoreaite. (Barbertonite), Pyroaurite, Sjogrenite, Iowaite, Chlormagaluminite, Hydrocalmite, Patina 1 (Greem Rust 1), Berthierine, Takovite, Reevesite, Honessite, Eardlyte, Meixenite ( Meixnerite). Furthermore, examples of the inorganic substance include a magnesium-aluminum solid solution as an inorganic substance with a layered structure, which can be produced by sintering hydrotalcite which is a layered double hydroxide. In addition, in this specification, this solid solution is also described as a kind of "hydrotalcite" in a broad sense.

On the other hand, as the zeolite as an inorganic substance contained in the non-aqueous secondary battery functional layer composition of the present invention, in addition to silicate minerals, zeolite having a compound according to the International Zeolite Association (IZA: International Zeolite Association) can also be mentioned. Zeolites with various framework structures defined. In addition, according to the definition of IZA, zeolite refers to "a compound that forms an open three-dimensional network and is composed of AB _n (n ≈ 2), and A has 4 bonds, B has 2 bonds, and the framework density (1nm ³ atomic number) is 20.5 or less".

These inorganic substances can be blended in the composition for a non-aqueous secondary battery functional layer of the present invention alone or in combination of two or more kinds. Among them, the composition for a non-aqueous secondary battery functional layer of the present invention preferably contains hydrotalcite and/or zeolite as an inorganic substance. This is because hydrotalcite and zeolite are excellent in capturing ability of metal ions, and can further improve the high-temperature cycle characteristics of a secondary battery having a functional layer formed using a composition for a functional layer. Furthermore, it is particularly preferable that the composition for a nonaqueous secondary battery functional layer of the present invention contains hydrotalcite as an inorganic substance. This is because hydrotalcite is less likely to be corroded by hydrofluoric acid generated in the secondary battery, so that the high-temperature cycle characteristics and low-temperature output characteristics of the secondary battery having a functional layer can be further improved.

In addition, the shape of the X-ray diffraction pattern and the magnitude of the interplanar distance of the integral of the diffraction intensity can be adjusted by the type and composition of the inorganic substance, and by subjecting the inorganic substance to heat treatment. In the case of adjustment by heat treatment, by changing the heating time and heating temperature, etc., an inorganic substance having a desired shape of the X-ray diffraction pattern and a size of the integrated interplanar distance of the desired diffraction intensity can be obtained.

—Amount of Inorganic Substances—

In the non-aqueous secondary battery functional layer composition of the present invention, the ratio of the inorganic substance in the composition to the total solid content is preferably 85.0% by mass or more, more preferably 90.0% by mass or more, particularly preferably 95.0% by mass Above, preferably 99.5% by mass or less. By setting the ratio of the inorganic substance in the composition to the total solid content to be 85.0% by mass or more, the increase in the Gurley value of the functional layer can be suppressed, and the secondary battery having the functional layer can exhibit excellent low-temperature output characteristics, and further The capture amount of metal ions can be increased, and the high-temperature cycle characteristics of the secondary battery can be further improved.

<Adhesive material>

Moreover, the composition for nonaqueous secondary battery functional layers of this invention is not specifically limited, It can contain a known binder. Specifically, as the binder, a conjugated diene polymer and an acrylic polymer are preferable, and an acrylic polymer is more preferable. In addition, these polymers may be used alone or in combination of two or more.

A conjugated diene-based polymer that can be preferably used as a binder material is a polymer containing a conjugated diene monomer unit. Furthermore, specific examples of conjugated diene polymers are not particularly limited, but include styrene-butadiene copolymers (SBR) and the like containing aromatic vinyl monomer units and aliphatic conjugated diene units. Copolymers of monomer units, butadiene rubber (BR), acrylic rubber (NBR) (copolymers containing acrylonitrile units and butadiene units), hydrogenated products of these, and the like.

Furthermore, as an acrylic polymer that can be preferably used as a binder, an acrylic polymer containing a (meth)acrylate monomer unit is preferably used. Here, as the (meth)acrylate monomer that can form a (meth)acrylate monomer unit, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and ethyl methacrylate can be used. , 2-ethylhexyl acrylate and other alkyl (meth)acrylates. In addition, in this invention, (meth)acryl means acryl and/or methacryl.

Furthermore, the acrylic polymer preferably contains at least one of a (meth)acrylonitrile monomer unit and an acid group-containing monomer unit, and more preferably contains both, in addition to the (meth)acrylate monomer unit. In addition, in this invention, (meth)acrylonitrile means acrylonitrile and/or methacrylonitrile. In addition, as the acid group-containing monomer that can form an acid group-containing monomer unit, monomers having an acid group such as monomers having a carboxylic acid group, monomers having a sulfonic acid group, and monomers having a phosphoric acid group are exemplified. .

Moreover, as a monomer which has a carboxylic acid group, a monocarboxylic acid, a dicarboxylic acid, etc. are mentioned, for example. As monocarboxylic acid, acrylic acid, methacrylic acid, crotonic acid etc. are mentioned, for example. As dicarboxylic acid, maleic acid, fumaric acid, itaconic acid etc. are mentioned, for example.

In addition, examples of monomers having sulfonic acid groups include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, ethyl (meth)acrylate 2-sulfonate , 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, etc.

Furthermore, examples of the monomer having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl phosphate -(meth)acryloyloxyethyl ester and the like.

In addition, in the present invention, "(meth)allyl" means allyl and/or methallyl, and (meth)acryl means acryloyl and/or methacryl. mean.

Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferable, a monocarboxylic acid is more preferable, and (meth)acrylic acid is still more preferable.

Moreover, an acidic group containing monomer may be used individually by 1 type, and may use it in combination of 2 or more types by arbitrary ratios.

Furthermore, when the secondary battery is a lithium ion secondary battery, the acrylic polymer that can be preferably used as a binder preferably contains a lithium salt of an unsaturated acid. The lithium salt of an unsaturated acid is not particularly limited, and examples thereof include a lithium salt of an unsaturated carboxylic acid, a lithium salt of an unsaturated sulfonic acid, and a lithium salt of an unsaturated phosphonic acid. Among these, lithium salts of unsaturated carboxylic acids and lithium salts of unsaturated sulfonic acids are preferably used as lithium salts of unsaturated acids. This is because lithium salts of unsaturated carboxylic acids and lithium salts of unsaturated sulfonic acids have a high degree of dissociation of lithium ions, so use of these lithium salts can further improve the low-temperature output characteristics of lithium ion secondary batteries.

Here, examples of lithium salts of the above-mentioned unsaturated carboxylic acids include: lithium salts of α,β-unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; maleic acid, fumaric acid, and itaconic acid; Lithium salts of α, β-unsaturated dicarboxylic acids such as lithium salts; lithium salts of partial esters of α, β-unsaturated polycarboxylic acids such as monomethyl maleate and monoethyl itaconate; oleic acid, linoleic acid Lithium salts of unsaturated fatty acids such as linolenic acid, linolenic acid, rumen acid, etc.

In addition, examples of lithium salts of the unsaturated sulfonic acid include vinylsulfonic acid, o-styrenesulfonic acid, m-styrenesulfonic acid, p-styrenesulfonic acid, 2-acrylamido-2-methylpropane Lithium salts of sulfonic acid (AMPS) and the like, various substitutes of these, and the like.

Furthermore, examples of the lithium salt of the above-mentioned unsaturated phosphonic acid include lithium salts of vinylphosphonic acid, o-styrenephosphonic acid, m-styrenephosphonic acid, p-styrenephosphonic acid, and various substitutes thereof. Wait.

Moreover, when the total solid content in the composition for a functional layer is 100% by mass, the content of the binder in the composition for a functional layer of a non-aqueous secondary battery is preferably 0.5% by mass or more, more preferably It is 1.0 mass % or more, Preferably it is 15.0 mass % or less, More preferably, it is 10.0 mass % or less. By setting the content of the binding material in the composition for the functional layer to 0.5% by mass or more relative to the total solid content, sufficient adhesiveness can be exhibited, and it is possible to suppress the detachment of inorganic substances from the functional layer, and it is also possible to make the functional layer The adhesion between the layer and the base material is improved, and the high-temperature cycle characteristics of the secondary battery with the functional layer are improved. In addition, by setting the content of the binder in the functional layer composition to 15.0% by mass or less relative to the total solid content, it is possible to suppress an increase in the Gurley value of the functional layer and to suppress a decrease in the ion conductivity of the functional layer. The increase in volume resistance of the functional layer improves the low-temperature output characteristics of the secondary battery having the functional layer.

Moreover, as a manufacturing method of the said polymer which can be used as a binder, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method etc. are mentioned, for example.

<Dispersion medium>

Moreover, it does not specifically limit as a dispersion medium of the composition for nonaqueous secondary battery functional layers of this invention, A known dispersion medium can be used. For example, examples of usable dispersion media include: water; amide compounds such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide; cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane Compounds; aromatic hydrocarbon compounds such as toluene and xylene; ketone compounds such as acetone, methyl ethyl ketone and cyclohexanone; ester compounds such as ethyl acetate, butyl acetate, γ-butyrolactone and ε-caprolactone; acetonitrile, propionitrile Nitrile compounds such as tetrahydrofuran, ethylene glycol diethyl ether and other ether compounds; methanol, ethanol, isopropanol, ethylene glycol, ethylene glycol monomethyl ether and other alcohol compounds, etc.

<additive>

Moreover, the composition for nonaqueous secondary battery functional layers may contain arbitrary other components other than the above-mentioned components. The above-mentioned other components are not particularly limited as long as they do not affect the battery reaction, and known components can be used. In addition, these other components may be used individually by 1 type, and may use it in combination of 2 or more types.

Examples of the above-mentioned other components include known additives such as dispersants, viscosity modifiers, and wetting agents.

(Manufacturing method of composition for functional layer of non-aqueous secondary battery)

The above-mentioned composition for a non-aqueous secondary battery functional layer of the present invention is not particularly limited, and can be obtained by mixing the above-mentioned inorganic substances, optional binders, and additives in the presence of a dispersion medium such as N-methylpyrrolidone.

Here, the mixing method of the above-mentioned components is not particularly limited, but in order to efficiently disperse the components, it is preferable to mix them using a disperser as a mixing device. Also, the disperser is preferably a device capable of uniformly dispersing and mixing the above components. Examples of the dispersing machine include non-media dispersing machines, ball mills, sand mills, pigment dispersing machines, choppers, ultrasonic dispersing machines, homogenizers, and planetary mixers.

In addition, the mixing order of the above-mentioned components is not particularly limited. For example, the above-mentioned components may be mixed at one time, or a binder may be added and dispersed when dispersing the inorganic substance in the dispersion medium.

When the mixed liquid containing the inorganic substance is dispersed, the solid content concentration of the mixed liquid is preferably 30% by mass or more and 60% by mass or less. This is because the dispersibility of the inorganic substance in the obtained composition for nonaqueous secondary battery functional layers can be improved. In addition, the obtained composition for a non-aqueous secondary battery functional layer preferably has a viscosity of 25 mPa·s or more and 85 mPa·s or less at 25° C. and 60 rpm using a B-type viscometer.

(Functional layer for non-aqueous secondary batteries)

The functional layer for a non-aqueous secondary battery of the present invention is formed from the above-mentioned composition for a functional layer of a non-aqueous secondary battery. For example, the functional layer for a non-aqueous secondary battery of the present invention can be formed by applying the above-mentioned composition for a functional layer on the surface of a suitable substrate to form a coating film, and then drying the formed coating film. That is, the functional layer for a nonaqueous secondary battery of the present invention is formed from a dried product of the composition for a functional layer for a nonaqueous secondary battery described above. Moreover, the functional layer for a non-aqueous secondary battery of the present invention contains an inorganic substance, and the inorganic substance is generally obtained by an X-ray diffraction method, with the diffraction intensity as the vertical axis and the diffraction angle 2θ as the horizontal axis. Among them, when the total integral of the above-mentioned diffraction intensity at the diffraction angle 2θ = 3° to 90° is set to 100%, the 2θ corresponding to the position where the integral of the diffraction intensity accumulated from the high diffraction angle side is 50% of the total integral The interplanar distance is 0.1 nm to 0.4 nm, and 80% of the interplanar distances are 0.15 nm to 0.70 nm. Furthermore, it is preferable that the functional layer for nonaqueous secondary batteries of this invention contains a binder in addition to the above-mentioned inorganic substance.

Furthermore, the functional layer for a nonaqueous secondary battery of the present invention is formed using the above-mentioned composition for a nonaqueous secondary battery functional layer, and contains the above-mentioned inorganic substance. Therefore, the functional layer for a non-aqueous secondary battery of the present invention can capture metal ions such as transition metal ions, so that the secondary battery having the functional layer exhibits excellent low-temperature output characteristics and high-temperature cycle characteristics.

Furthermore, the functional layer for a non-aqueous secondary battery of the present invention preferably has a thickness of not less than 1.5 μm and not more than 3.5 μm. By making the thickness of a functional layer more than the said lower limit, the metal capture amount of a functional layer can be fully increased, and the cycle characteristic of the secondary battery which has a functional layer can be improved. In addition, by making the thickness of the functional layer below the above-mentioned upper limit, the Gurley value of the functional layer can be avoided from becoming excessively high, the increase in the volume resistance of the functional layer can be suppressed, and the output characteristics of the secondary battery having the functional layer can be improved. improve.

In addition, in this invention, the thickness of a functional layer means the average value of the layer thickness measured at arbitrary 10 places of a functional layer.

<Substrate>

Here, the substrate for coating the composition for the functional layer is not limited, for example, it can be carried out as follows: a coating film of the composition for the functional layer is formed on the surface of the release substrate, and the coating film is dried to form a functional layer. Layer peel release substrate. In this way, the functional layer peeled from the release base material can also be used as a self-supporting film to form a battery member of a secondary battery. Specifically, a separator having a functional layer may be formed by laminating a functional layer peeled from a release base material on a separator base material, or may be formed by laminating a functional layer peeled from a release base material on an electrode base material. An electrode having a functional layer is formed.

However, it is preferable to use a separator base material or an electrode base material as the base material from the viewpoint of improving the production efficiency of the battery member by omitting the step of peeling off the functional layer. The functional layer provided on the separator base material and the electrode base material can not only exhibit the metal capture ability, but also can be suitably used as a protective layer for improving the heat resistance, strength, etc. of the separator and the electrode.

[Spacer base material]

The spacer base material is not particularly limited, and known spacer base materials such as organic spacer base materials can be mentioned. The organic spacer substrate is a porous member formed of an organic material. Examples of organic spacer substrates include microporous films or nonwoven fabrics made of polyolefin resins such as polyethylene and polypropylene, and aromatic polyamide resins. Microporous films made of polyethylene are preferred from the viewpoint of excellent strength. Porous film, non-woven fabric.

[Electrode base material]

The electrode base material (positive electrode base material and negative electrode base material) is not particularly limited, and an electrode base material in which an electrode composite material layer is formed on a current collector is exemplified. Here, the current collector and the binding material for the electrode composite material layer (the binding material for the positive electrode composite material layer, the binding material for the negative electrode composite material layer) and the method of forming the electrode composite material layer on the current collector can use known The substances and methods include, for example, those described in JP-A-2013-145763.

[Electrode active material]

As the electrode active material in the electrode composite material layer, both inorganic compounds and organic compounds can be used as long as they can reversibly intercalate and deintercalate ions that contribute to the battery reaction by applying a potential to the electrolyte.

As the positive electrode active material, a positive electrode active material formed of an inorganic compound can be used. In lithium ion secondary batteries, for example, transition metal oxides, composite oxides of lithium and transition metals, and transition metal sulfides can be used as positive electrode active materials made of inorganic compounds. As the above-mentioned transition metal, a divalent or higher transition metal is preferable, and any one of Co, Mn, Fe, and Ni is more preferable. By using a positive electrode active material having transition metals such as Co, Mn, Fe, and Ni as the positive electrode active material, it is possible to further increase the capacity of the secondary battery. In addition, if the functional layer of the present invention is used, even when a positive electrode active material containing a transition metal is used, it is possible to suppress a decrease in the electrical characteristics of the secondary battery due to elution of the transition metal.

Specific examples of the inorganic compound used as the positive electrode active material include: LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (NMC), LiFePO _4. Lithium-containing composite metal oxides such as LiFeVO ₄ ; transition metal sulfides such as TiS ₂ , TiS ₃ , and amorphous MoS ₂ ; Cu ₂ V ₂ O ₃ , amorphous V ₂ OP ₂ O ₅ , MoO ₃ , V ₂ O _5. V ₆ O ₁₃ and other transition metal oxides, etc.

Among them, LiCoO ₂ and LiNi _1/3 Mn _1/3 Co _1/3 O ₂ are preferably used as the positive electrode active material, and LiNi _1/3 Mn _1/3 Co _1/3 O ₂ is particularly _preferable .

In addition, these positive electrode active materials may be used alone or in combination of two or more. In addition, a mixture of the above-mentioned inorganic compound and an organic compound such as a conductive polymer such as polyacetylene or polyparaphenylene can also be used as the positive electrode active material.

Examples of the negative electrode active material include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microspheres, and pitch-based carbon fibers; and conductive polymers such as polyacene. In addition, metals such as silicon, tin, zinc, manganese, iron, and nickel, and alloys thereof; oxides of the above metals or alloys; sulfates of the above metals or alloys, and the like are also exemplified. In addition, metallic lithium; lithium alloys such as Li—Al, Li—Bi—Cd, and Li—Sn—Cd; lithium transition metal nitrides; silicon and the like can also be used. In addition, these negative electrode active materials may be used alone or in combination of two or more.

<Formation method of functional layer for non-aqueous secondary battery>

As a method of forming a functional layer on a base material such as the above-mentioned separator base material and electrode base material, the following methods are mentioned.

1) The composition for the functional layer of the non-aqueous secondary battery of the present invention is coated on the surface of the separator base material or the electrode base material (in the case of the electrode base material, it is the surface on the side of the electrode composite material layer, the same below), and then drying method;

2) A method of drying the separator base material or the electrode base material in the non-aqueous secondary battery functional layer composition of the present invention;

3) Coating the composition for a functional layer of a non-aqueous secondary battery of the present invention on a release substrate, drying to produce a functional layer, and transferring the obtained functional layer to the surface of a separator substrate or an electrode substrate Methods;

Among these, the method of 1) above is particularly preferable since it is easy to control the layer thickness of the functional layer. Specifically, the method of 1) above includes a step of applying the composition for a functional layer on a substrate (coating step), drying the composition for a functional layer applied on the substrate to form a functional layer. process (functional layer formation process).

[coating process]

Moreover, in the coating step, the method of coating the composition for the functional layer on the substrate is not particularly limited, and examples thereof include doctor blade coating, reverse roll coating, direct roll coating, gravure printing, Extrusion method, brushing method and other methods.

[Functional layer formation process]

In addition, in the functional layer forming step, as a method of drying the composition for a functional layer on the substrate, known methods can be used without particular limitation, and examples thereof include drying with warm air, hot air, and low-humidity air. , Vacuum drying, a drying method using irradiation of infrared rays, electron beams, etc. The drying conditions are not particularly limited, but the drying temperature is preferably 50 to 150° C., and the drying time is preferably 3 to 30 minutes.

(battery components with functional layers)

As far as the battery member (separator and electrode) having the functional layer of the present invention is concerned, as long as the effect of the present invention is not significantly impaired, in addition to having a separator base material or an electrode base material and the functional layer of the present invention, it may also be There are structural elements other than the above-mentioned functional layer of the present invention.

Here, the structural elements other than the functional layer of the present invention are not particularly limited as long as they do not correspond to the functional layer of the present invention, and are provided on the functional layer of the present invention and used for bonding battery components. adhesive layer etc.

(Non-aqueous secondary battery)

The nonaqueous secondary battery of the present invention is a nonaqueous secondary battery having the above-mentioned functional layer for a nonaqueous secondary battery of the present invention. More specifically, the non-aqueous secondary battery of the present invention has a positive electrode, a negative electrode, a separator, and an electrolytic solution, and the above-mentioned functional layer for a non-aqueous secondary battery is included in at least one of the positive electrode, the negative electrode, and the separator as battery components. . Preferably, the functional layer for a non-aqueous secondary battery of the present invention is contained in a separator. This is because metal ions derived from the positive electrode active material can be captured more efficiently, and the electrical characteristics (such as low-temperature output characteristics and high-temperature cycle characteristics) of a secondary battery having this separator can be further improved. Moreover, since the non-aqueous secondary battery of the present invention has the functional layer obtained from the composition for the functional layer of the non-aqueous secondary battery of the present invention, it can Exhibits excellent electrical characteristics (such as low-temperature output characteristics and high-temperature cycle characteristics).

<Positive electrode, negative electrode and separator>

At least one of the positive electrode, the negative electrode, and the separator used in the secondary battery of the present invention contains the functional layer of the present invention. Specifically, as the positive electrode and negative electrode having a functional layer, an electrode in which the functional layer of the present invention is provided on an electrode base material in which an electrode composite material layer is formed on a current collector can be used. Moreover, what provided the functional layer of this invention on the spacer base material as a spacer which has a functional layer can be used. In addition, as the electrode base material and the separator base material, the same electrode base material and separator base material as those mentioned in the item of "functional layer for non-aqueous secondary battery" can be used. .

In addition, the positive electrode, the negative electrode, and the separator that do not have a functional layer are not particularly limited, and an electrode formed of the above-mentioned electrode base material and a separator formed of the above-mentioned separator base material can be used.

<Electrolyte>

As the electrolytic solution, an organic electrolytic solution obtained by dissolving a supporting electrolyte in an organic solvent is generally used. As a supporting electrolyte, lithium salts can be used in, for example, lithium ion secondary batteries. Examples of lithium salts include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ )NLi, etc. Among them, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferred because they are easily dissolved in a solvent and exhibit a high degree of dissociation. In addition, one type of electrolyte may be used alone, or two or more types may be used in combination. Generally, lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, in lithium ion secondary batteries, it is preferable to use: dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate Ester (DEC), propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other carbonates; γ-butyrolactone, methyl formate, etc. Esters; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide, etc. In addition, a mixed solution of these solvents can also be used. Among them, carbonates are preferable because they have a high dielectric constant and a wide stable potential range. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be. Therefore, the lithium ion conductivity can be adjusted by the type of solvent.

In addition, the concentration of the electrolyte in the electrolytic solution can be appropriately adjusted. In addition, known additives may also be added to the electrolytic solution.

(Manufacturing method of non-aqueous secondary battery)

The above-mentioned non-aqueous secondary battery of the present invention can be manufactured by, for example, stacking the positive electrode and the negative electrode through a separator, winding, folding, etc., as necessary, and putting them into a battery container, and injecting electrolytic solution into the battery container. Liquid and seal. In addition, at least one member among the positive electrode, the negative electrode, and the separator is used as a member with a functional layer. In addition, in the battery container, if necessary, overcurrent prevention elements such as expanded metal, fuses, and PTC elements, guide plates, etc. can also be placed to prevent internal pressure rise and overcharge and discharge of the battery. The shape of the battery may be, for example, any of coin type, button type, sheet type, cylindrical type, square type, flat type, and the like.

Example

Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In addition, in the following description, unless otherwise specified, "%" and "part" which show an amount are mass basis.

In Examples and Comparative Examples, X-ray diffraction intensity and volume average particle size of inorganic substances, transition metal ion capture amount and ion conductivity (Gurley value increase rate) of the functional layer, and high-temperature cycle characteristics of the secondary battery and low-temperature output characteristics were measured and evaluated by the following methods.

<X-ray diffraction intensity of inorganic substances>

The X-ray diffraction intensity of the inorganic substances in Examples and Comparative Examples was obtained by the following measurement: using an X-ray diffraction device (product name: RINT2500, manufactured by Rigaku Corporation), using Cu-Kα rays using a Cu tube as an X-ray source , assuming that the temperature is 25°C, the accelerating voltage is 40kV, the scattering slit is 1°, the light receiving slit is 0.3mm, and the diffraction angle 2θ is 3°～90°.

Furthermore, when the total integral accumulated from the high-angle side of the diffraction angle 2θ (that is, 2θ=90°) of the obtained diffraction intensity is 100%, the integral of the diffraction intensity of the inorganic layered compound is 50%, respectively. The value of the interplanar distance corresponding to 2θ and the value of the interplanar distance corresponding to 2θ at 80%.

<Volume average particle diameter of inorganic substances>

The volume-average particle diameter (D50) of the inorganic substances used in Examples and Comparative Examples is the value of the particle diameter when the cumulative value is 50% in the volume-based particle size distribution, and is obtained by supplying ion-exchanged water Add the inorganic substances used in Examples and Comparative Examples so that the scattering intensity is about 50% in the flow colorimetric cell (flowcell), and after ultrasonic dispersion, use a laser diffraction particle size distribution measuring device (Shimadzu Corporation Co., Ltd. "SALD-7100" manufactured) measures scattered light.

<Transition metal ion capture amount of functional layer>

When measuring the transition metal capture amount of the non-aqueous secondary battery functional layer made in the examples and comparative examples, at first, the spacer coated with the composition for the non ^- aqueous secondary battery functional layer was punched into an area of 100 cm size, made into a test piece, and measured the mass (A) of the test piece before trapping transition metal ions. Next, the separator base material not coated with the composition for the functional layer of the non-aqueous secondary battery was punched out to a size of 100 cm ² , and its mass was measured as (B). The value of the mass (A) minus the mass (B) was taken as the mass of the functional layer before trapping transition metal ions.

Next, _cobalt chloride ( Anhydrous) (CoCl ₂ ), nickel chloride (anhydrous) (NiCl ₂ ), manganese chloride (anhydrous) (MnCl ₂ ) were used as transition metal ion sources, and the electrolytic The liquid creates a state in which transition metal ions exist in a predetermined ratio as in a non-aqueous secondary battery. Next, the above-mentioned test piece was put into a glass container, 15 g of the above-mentioned electrolytic solution in which cobalt chloride, manganese chloride, and nickel chloride were dissolved was added, the test piece was immersed, and it was left to stand at 25° C. for 5 days. Then, the test piece was taken out, and the test piece was sufficiently washed with diethyl carbonate to fully wipe off the diethyl carbonate adhering to the surface of the test piece. Then, the test piece was put into a beaker made of Teflon (registered trademark), sulfuric acid and nitric acid (sulfuric acid: nitric acid = 0.1:2 (volume ratio)) were added, and the test piece was heated on a hot plate until the test piece was carbonized. Furthermore, after adding nitric acid and perchloric acid (nitric acid:perchloric acid=2:0.2 (volume ratio)), add perchloric acid and hydrofluoric acid (perchloric acid:hydrofluoric acid=2:0.2 (volume ratio)) , heated to produce white smoke. Next, 20 ml of nitric acid and ultrapure water (nitric acid:ultrapure water=0.5:10 (volume ratio)) were added and heated. After standing to cool, ultrapure water was added so that the total amount would be 100 ml, and a transition metal ion solution containing transition metal ions was obtained. The amounts of cobalt, nickel, and manganese in the obtained transition metal ion solution were measured using an ICP mass analyzer (manufactured by PerkinElmer, "ELAN DRS II"). Then, by dividing the total amount of cobalt, nickel, and manganese in the transition metal ion solution by the mass of the functional layer before capturing the transition metal ion obtained as described above, the transition metal ion amount in the functional layer was calculated ( mass ppm), and the obtained value was taken as the transition metal ion capture amount of the functional layer for a non-aqueous secondary battery. The larger the capture amount of the transition metal ion is, the higher the transition metal ion capture capability per unit mass of the functional layer for a non-aqueous secondary battery is.

A: The capture amount of transition metal ions is above 1000ppm

B: The capture amount of transition metal ions is more than 500ppm and less than 1000ppm

C: The capture amount of transition metal ions is more than 100ppm and less than 500ppm

D: The capture amount of transition metal ions is less than 100ppm

<Ionic conductivity of functional layer (Gurley increase rate)>

For forming the spacer with the functional layer for the non-aqueous secondary battery and the spacer base material before the functional layer, a digital type Wangken type air permeability and smoothness tester (manufactured by Asahi Seiko Co., Ltd., "EYO-5- 1M-R") to measure the Gurley value (sec/100cc). Specifically, the Gurley value is obtained from the Gurley value G0 of the "spacer substrate" before the formation of the functional layer and the Gurley value G1 of the "spacer with the functional layer" after the formation of the functional layer The rate of increase ΔG (=(G1/G0)×100(%)) was evaluated according to the following criteria. The smaller the increase rate ΔG of the Gurley value, the better the ion conductivity of the functional layer for a non-aqueous secondary battery.

A: ΔG is less than 130%.

B: ΔG is 130% or more and less than 200%

<High Temperature Cycle Characteristics of Secondary Batteries>

The discharge capacity of 800mAh wound-type laminated battery cell was measured at 45°C by using a constant current method at 0.5C, repeating 200 cycles of charging to 4.35V and discharging to 3V, and measuring the discharge capacity. Calculate the ratio of the discharge capacity at the end of 200 cycles to the discharge capacity at the end of 3 cycles in percentage form using the average value of 5 battery cells as the measured value, calculate the charge-discharge capacity retention rate, and evaluate according to the following criteria . The higher the value, the better the high-temperature cycle characteristics of the secondary battery.

A: The charge-discharge capacity retention rate was 80% or more.

B: The charge-discharge capacity retention ratio is 70% or more and less than 80%.

C: The charge-discharge capacity retention rate is 60% or more and less than 70%.

D: The charge-discharge capacity retention rate is less than 60%.

<Low temperature output characteristics of secondary batteries>

A wound-type lithium-ion secondary battery with a discharge capacity of 800mAh was left to stand at 25°C for 24 hours, and then charged at a charge rate of 4.35V and 0.1C for 5 hours at 25°C to measure The voltage V0 at this time. Then, a discharge operation was performed at a discharge rate of 1 C in an environment of -10° C., and a voltage V1 15 seconds after the start of discharge was measured. Then, the voltage change ΔV (=V0-V1) was obtained and evaluated according to the following criteria. The smaller the value of the voltage change ΔV, the better the low-temperature output characteristics of the secondary battery.

A: The voltage change ΔV is less than 350mV

B: The voltage change ΔV is more than 350mV and less than 500mV

C: The voltage change ΔV is more than 500mV

(Example 1)

<Preparation of adhesive material>

In a 5MPa pressure vessel with a stirrer, add 30 parts of butyl acrylate as (meth)acrylate monomer, 35 parts of acrylonitrile as (meth)acrylonitrile monomer, 30 parts of Lithium styrenesulfonate of lithium salt of saturated sulfonic acid, 5 parts of methacrylic acid as a monomer having a carboxylic acid group, 1.0 part of polyoxyalkylene alkenyl ether ammonium sulfate as a reactive surfactant, 400 parts ion-exchanged water and 1.0 part of perpotassium sulfate as a polymerization initiator were sufficiently stirred, and then heated to 65° C. to perform polymerization. When the polymerization conversion rate reached 96%, cooling was performed to terminate the reaction, and a precursor (aqueous dispersion liquid) of the binder material was obtained.

With respect to 100 parts (solid content: 24.75 parts) of the precursor of the bonding material, 350 parts of N-methylpyrrolidone (NMP) was added, water was evaporated under reduced pressure and 40.62 parts of NMP were evaporated to obtain a bonding material containing Dispersion liquid of material (solid content concentration: 8%).

<Preparation of composition for functional layer of non-aqueous secondary battery>

Add 97 parts by mass of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., "KW2000", composition: Mg _0.7 Al _0.3 O _1.15 ) as an inorganic substance, 3 parts by mass of the above-mentioned binding material in terms of solid content, and add NMP to a solid content concentration of 40% by mass. Next, in a non-media dispersing device (manufactured by Ashizawa Finetech Ltd., "LMZ-015"), the inorganic substance was dispersed at a rotation speed of 6 m/s and a flow rate of 0.3 L/min using beads with a diameter of 0.4 mm to prepare a slurry The non-aqueous secondary battery functional layer composition.

The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 32 mPa·s at 60 rpm.

<Production of separator for secondary battery>

An organic spacer (made of polyethylene, thickness 12 μm, Gurley value 150 s/100 cc) formed of a polyethylene porous base material was prepared. The above-mentioned composition for a functional layer was applied to one side of the prepared organic spacer, and dried at 50° C. for 3 minutes. Thus, an organic spacer having a functional layer with a thickness of 3 μm on one surface was obtained.

<Production of Negative Electrode>

In a 5MPa pressure vessel with a stirrer, add 33.5 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 62 parts of styrene, 1 part of 2-hydroxyethyl acrylate, 0.4 parts of Sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water and 0.5 parts of potassium persulfate as a polymerization initiator were fully stirred, then heated to 50°C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was terminated by cooling to obtain a mixture containing a binder (SBR). Add 5% sodium hydroxide aqueous solution to the mixture containing the bonding material (SBR), adjust the pH to 8, remove unreacted monomers by heating and vacuum distillation, and then cool to below 30°C to obtain the desired viscosity. Aqueous dispersion of junction material (SBR).

Next, add 100 parts of artificial graphite (volume average particle diameter: 15.6 μm) as a negative electrode active material, and 1 part of carboxymethylcellulose sodium salt as a thickener (Nippon Paper Co., Ltd. To a 2% aqueous solution manufactured by the company, "MAC350HC"), ion-exchanged water was added to the 2% aqueous solution so that the solid content concentration became 68%, and then mixed at 25° C. for 60 minutes. After adjusting to a solid content concentration of 62% using ion-exchanged water, it was further mixed at 25° C. for 15 minutes to obtain a liquid mixture. To the obtained mixed solution, 1.5 parts by mass of the above-mentioned binder (SBR) was added in terms of solid content equivalent, adjusted to a final solid content concentration of 52% with ion-exchanged water, and further mixed for 10 minutes. The defoaming treatment was carried out under reduced pressure to obtain a slurry composition for secondary battery negative electrodes with good fluidity.

Then, the obtained negative electrode slurry composition was coated on a copper foil having a thickness of 20 μm as a current collector so that the film thickness after drying was about 150 μm using a chip coater, and dried. This drying was carried out by conveying the copper foil in a 60° C. oven at a speed of 0.5 m/min for 2 minutes. Then, it was heat-treated at 120° C. for 2 minutes to obtain a negative electrode raw material before pressing. The unpressed negative electrode raw material was rolled using a roll press to obtain a pressed negative electrode with a negative electrode composite material layer thickness of 80 μm.

<positive pole>

Add 100 parts of LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (NMC) with a volume average particle diameter of 12 μm as the positive electrode active material, 2 parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.) "HS-100"), and PVDF (manufactured by KUREHA CORPORATION, "#7208") as a binder for positive electrodes (manufactured by KUREHA CORPORATION, "#7208"), which is 2 parts in terms of solid content equivalents, to which NMP was added so that the total solid content concentration was 70 %, to obtain a mixed solution. The obtained liquid mixture was mixed using a planetary mixer to prepare a positive electrode slurry composition.

Using a notched wheel coater, the obtained positive electrode slurry composition was coated on an aluminum foil having a thickness of 20 μm as a current collector so that the film thickness after drying was about 150 μm, and dried. This drying was carried out by conveying the copper foil in a 60° C. oven at a speed of 0.5 m/min for 2 minutes. Then, heat treatment at 120° C. for 2 minutes to obtain a positive electrode raw material before pressing. The unpressed positive electrode raw material was rolled by roll pressing to obtain a pressed positive electrode with a positive electrode composite material layer thickness of 80 μm.

<Secondary battery>

The obtained pressed positive electrode was cut into 49cm × 5cm, and placed with the surface on the side of the positive electrode composite material layer as the upper side, and the spacer with a functional layer cut into 55cm × 5.5cm was divided into positive electrode composite material layer and functional layer. Layers are disposed on the positive electrode in an opposing manner. Furthermore, the obtained pressed negative electrode was cut into a square of 50 cm×5.2 cm, and placed on the separator with the surface on the side of the negative electrode composite material layer facing the separator. This was wound up using a winder to obtain a wound body. Press the winding body at 60°C and 0.5 MPa to form a flat body, pack it with an aluminum packaging material casing as a battery casing, and inject an electrolyte solution (solvent: EC/DEC/VC=68.5/30/1.5 (volume ratio), Electrolyte: LiPF ₆ with a concentration of 1M) until there is no air remaining, and then in order to seal the opening of the aluminum packaging material casing, heat seal the aluminum packaging material casing at 150°C to manufacture a wound-type lithium-ion battery with a discharge capacity of 800mAh. secondary battery.

Then, the high-temperature cycle characteristics and low-temperature output characteristics of the secondary batteries were evaluated. The results are shown in Table 1.

(Example 2)

When preparing the composition for the functional layer, the hydrotalcite of the inorganic substance is 88 parts by mass, and the binding material is 12 parts by mass, except that, it is carried out in the same manner as in Example 1, and the binding material and the composition for the functional layer are produced. , separators, negative electrodes, positive electrodes and secondary batteries. The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 80 mPa·s at 60 rpm. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)

Various evaluations were performed in the same manner as in Example 1 except that hydrotalcite having a composition of (Mg _0.6 Al _0.4 O _1.15 ) was used as the inorganic substance. The results are shown in Table 1. In addition, each XRD diffraction intensity of this hydrotalcite is shown in Table 1, respectively.

(Example 4)

Various evaluations were performed in the same manner as in Example 1 except that hydrotalcite having a composition of (Mg _0.75 Al _0.25 O _1.15 ) was used as the inorganic substance. The results are shown in Table 1. In addition, each XRD diffraction intensity of this hydrotalcite is shown in Table 1, respectively.

(Example 5)

As an inorganic substance, except having used the hydrotalcite obtained by heating hydrotalcite "KW2000" at 800 degreeC for 1 hour, it carried out similarly to Example 1, and performed various evaluation. The results are shown in Table 1. In addition, each XRD diffraction intensity of this hydrotalcite is shown in Table 1, respectively.

(Example 6)

As an inorganic substance, except having used the hydrotalcite obtained by heating hydrotalcite "KW2000" at 1200 degreeC for 1 hour, it carried out similarly to Example 1, and performed various evaluation. The results are shown in Table 1. In addition, each XRD diffraction intensity of this hydrotalcite is shown in Table 1, respectively.

(Example 7)

The inorganic substance is changed to have an interplanar spacing of 0.32 nm corresponding to 2θ at a position where the integral of diffraction intensity integrated from the high diffraction angle side is 50% of the total integral, and an interplanar spacing of 0.61 nm corresponding to 2θ at a position of 80%. Zeolite (manufactured by Toagosei Co., Ltd., "IXEPLAS-A1") was carried out in the same manner as in Example 1 to produce a binder, a composition for a functional layer, a separator, a negative electrode, a positive electrode, and a secondary battery. The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 55 mPa·s at 60 rpm. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(comparative example 1)

The inorganic substance is changed to have an interplanar spacing of 0.6 nm corresponding to 2θ at a position where the integral of diffraction intensity integrated from the high diffraction angle side is 50% of the total integral, and an interplanar spacing of 0.9 nm corresponding to 2θ at a position of 80%. Zeolite (manufactured by Toagosei Co., Ltd., "IXE-300") was carried out in the same manner as in Example 1 to produce a binder, a composition for a functional layer, a separator, a negative electrode, a positive electrode, and a secondary battery. The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 70 mPa·s at 60 rpm. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(comparative example 2)

Inorganic substances were changed to have an interplanar spacing of 0.5 nm corresponding to 2θ at a position where the integral of diffraction intensity integrated from the high diffraction angle side is 50% of the total integral, and an interplanar spacing of 0.7 nm corresponding to 2θ at a position of 80%. Hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., "DHT-4A-2", composition: Mg _4.3 Al ₂ (OH) _12.6 CO ₃ ·mH ₂ O), except that, it was carried out in the same manner as in Example 1, and the adhesive was produced. Junction materials, compositions for functional layers, separators, negative electrodes, positive electrodes, and secondary batteries. The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 68 mPa·s at 60 rpm. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(comparative example 3)

The inorganic substance is changed to have an interplanar spacing of 0.38 nm corresponding to 2θ at a position where the integral of diffraction intensity integrated from the high diffraction angle side is 50% of the total integral, and an interplanar spacing of 0.72 nm corresponding to 2θ at a position of 80%. Except for the hydrotalcite, it carried out similarly to Example 1, and produced the binder, the composition for functional layers, a separator, a negative electrode, a positive electrode, and a secondary battery. The viscosity of the prepared functional layer composition was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., “TVB-10M”), and was 70 mPa·s at 60 rpm. Then, various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[Table 1]

From Table 1, it can be seen that in Examples 1 to 7 using the composition for a functional layer containing an inorganic substance having a predetermined interplanar distance, the function that enables the secondary battery to exhibit excellent high-temperature cycle characteristics and low-temperature output characteristics can be formed. Floor.

In addition, it can be seen from Table 1 that if the functional layers of Comparative Examples 1 to 3 using functional layer compositions containing inorganic substances that do not have a predetermined interplanar distance, the secondary battery cannot exhibit excellent high-temperature cycle characteristics and Low temperature output characteristics.

Industrial availability

According to this invention, the composition for nonaqueous secondary battery functional layers which can improve the electrical characteristic of a secondary battery can be provided.

Moreover, according to this invention, the functional layer for nonaqueous secondary batteries which can improve the electrical characteristic of a secondary battery can be provided.

Furthermore, according to the present invention, it is possible to provide a non-aqueous secondary battery excellent in electrical characteristics such as low-temperature output characteristics and high-temperature cycle characteristics.

Claims (7)

1. a kind of non-aqueous secondary battery functional layer composition, comprising inorganic matter,

The inorganic matter it is being obtained by X-ray diffraction method, penetrated for the X of transverse axis by the longitudinal axis, 2 θ of angle of diffraction of diffracted intensity In ray diffraction diagram spectrum, when the total mark of the diffracted intensity of 2 θ=3 °~90 ° of angle of diffraction is set to 100%,

The integration of the diffracted intensity with adding up from high angle of diffraction side is corresponding for 2 θ of 50% position of the total mark Interplanar distance be more than 0.1nm and below 0.4nm, and interplanar distance corresponding with 2 θ of 80% position for more than 0.15nm and Below 0.70nm.

2. non-aqueous secondary battery functional layer composition according to claim 1, wherein, the inorganic matter is relative to complete The ratio of portion's solid constituent is more than 85 mass %.

3. non-aqueous secondary battery functional layer composition according to claim 1 or 2, wherein, the inorganic matter is water Talcum and/or zeolite.

4. a kind of non-aqueous secondary battery functional layer, it is that usage right requires the non-water system any one of 1~3 secondary Battery functi on layer composition and formed.

5. a kind of non-aqueous secondary battery, has the non-aqueous secondary battery functional layer described in claim 4.

6. non-aqueous secondary battery according to claim 5, it is with cathode, anode, electrolyte and distance piece, between described Spacing body has the non-aqueous secondary battery functional layer.

7. the non-aqueous secondary battery according to claim 5 or 6, wherein, the cathode, which includes, has Co, Mn, Fe and Ni In it is any more than positive active material.