WO2019065705A1 - Binder for nonaqueous electrolyte secondary battery electrode, electrode mixture for nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and electric apparatus - Google Patents

Abstract

Provided is a binder for an electrode which has sufficient binding force and can reduce resistance of a nonaqueous electrolyte secondary battery. The binder for a nonaqueous electrolyte secondary battery electrode includes: a copolymer of a vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralization product; and a polyvinyl alcohol.

Description

Binder for nonaqueous electrolyte secondary battery electrode, electrode mixture for nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery, and electric device

The present invention comprises a binder for a non-aqueous electrolyte secondary battery electrode, an electrode mixture for a non-aqueous electrolyte secondary battery including the binder, an electrode for a non-aqueous electrolyte secondary battery using the electrode mixture, and the electrode The present invention relates to a non-aqueous electrolyte secondary battery and an electric device provided with the secondary battery.

In recent years, with the spread of portable electronic devices such as laptop computers, smartphones, portable game devices, PDAs, etc., secondary batteries used as a power source to reduce the weight of these devices and enable long-time use There is a demand for miniaturization and high energy density of

In particular, in recent years, the use as a power source for vehicles such as electric vehicles and electric motorcycles has been expanded. As secondary batteries to be used for such vehicle power supplies, batteries that can operate not only at high energy density but also in a wide temperature range are required, and various non-aqueous electrolyte secondary batteries are required. Proposed.

Conventionally, nickel-cadmium batteries, nickel-hydrogen batteries, etc. have mainly been used as non-aqueous electrolyte secondary batteries, but the use of lithium ion secondary batteries has increased due to the above-mentioned demands for miniaturization and high energy density. Tend to

An electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery usually has a binder solution in which a binder for an electrode (hereinafter, may be simply referred to as a binder) dissolved in a solvent, or a binder dispersed in a dispersion medium A method of applying a battery electrode mixture slurry (hereinafter may be simply referred to as a slurry) obtained by mixing an active material (electrode active material) and a conductive support agent to a slurry on a current collector, and drying the solvent and the dispersion medium It is manufactured by removing.

In a lithium ion secondary battery, for example, a positive electrode is a positive electrode mixture slurry in which lithium cobaltate (LiCoO ₂ ) as an active material, polyvinylidene fluoride (PVDF) as a binder, and carbon black as a conductive additive are dispersed in a dispersion medium. Obtained by coating and drying on an aluminum foil current collector.

In addition, the negative electrode may be any of graphite (graphite) as an active material, carboxymethylcellulose (CMC) as a binder, styrene butadiene rubber (SBR), PVDF or polyimide, carbon black as a conductive aid, in water or an organic solvent It can be obtained by coating and drying the dispersed negative electrode mixture slurry on a copper foil current collector.

Furthermore, in order to increase the capacity of lithium ion secondary batteries, various graphites have been studied as negative electrode active materials. In particular, in artificial graphite, it is known that the energy capacity as the negative electrode active material changes when the crystalline state changes due to the difference in the carbonization temperature and the raw materials (see Patent Documents 1 to 3).

JP-A-8-264180 Unexamined-Japanese-Patent No. 4-188559 Japanese Patent Application Laid-Open No. 10-284082 WO 2004/049475 Japanese Patent Application Laid-Open No. 10-302799

When various graphites are used as the negative electrode active material, it has been necessary to use a large amount of binder because PVDF, which has conventionally been used as a binder, has low binding strength and low flexibility. By using a large amount of the binder, the amount of the active material relatively decreases, and the battery capacity decreases, and there is a problem that the internal resistance of the battery increases. Furthermore, since PVDF dissolves only in organic solvents, other binders capable of reducing environmental impact have been proposed (see Patent Documents 4 to 5). However, when such binders are used, the performance as a battery is not sufficient.

Furthermore, using a styrene butadiene rubber (SBR) as a water-based binder with which the effect of reducing an environmental impact is anticipated without reducing binding capacity is examined. However, since SBR having a rubber property, which is an insulator, is present on the surface of the active material, sufficient rate characteristics can not be obtained, and the resistance in the electrode is increased.

Under such circumstances, the main object of the present invention is to provide a binder for an electrode having sufficient binding power and capable of reducing the resistance of a non-aqueous electrolyte secondary battery.

The present inventors diligently studied to solve the above problems. As a result, a binder containing polyvinyl alcohol and a copolymer of an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and polyvinyl alcohol is used for an electrode of a non-aqueous electrolyte secondary battery to exhibit sufficient binding power. It was further found that the resistance of the non-aqueous electrolyte secondary battery can be further reduced.

That is, the present invention provides an invention having the following configuration.
Item 1. A binder for a non-aqueous electrolyte secondary battery electrode, comprising a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and polyvinyl alcohol.
Item 2. The non-aqueous electrolyte according to item 1, wherein the copolymer composition ratio of the vinyl alcohol to the alkali metal neutralized product of the ethylenically unsaturated carboxylic acid in the copolymer is 95/5 to 5/95 in molar ratio. Binder for secondary battery electrodes.
Item 3. The binder for non-aqueous electrolyte secondary battery electrodes according to claim 1 or 2, wherein the ethylenically unsaturated carboxylic acid alkali metal neutralized product is a (meth) acrylic acid alkali metal neutralized product.
Item 4. The binder for a non-aqueous electrolyte secondary battery electrode according to any one of Items 1 to 3, wherein a mass ratio of the copolymer to the polyvinyl alcohol is 95/5 to 70/30.
Item 5. An electrode mixture for a non-aqueous electrolyte secondary battery, comprising the electrode active material, a conductive additive, and the binder for a non-aqueous electrolyte secondary battery electrode according to any one of Items 1 to 4.
Item 6. The non-aqueous electrolyte secondary according to item 5, wherein the content of the binder is 0.5 to 40 parts by mass with respect to 100 parts by mass in total of the electrode active material, the conductive auxiliary agent, and the binder. Electrode mixture for batteries.
Item 7. 7. An electrode for a non-aqueous electrolyte secondary battery produced using the electrode mixture for a non-aqueous electrolyte secondary battery according to Item 5 or 6.
Item 8. Item 8. A non-aqueous electrolyte secondary battery comprising the electrode for a non-aqueous electrolyte secondary battery according to Item 7.
Item 9. Item 9. An electrical device comprising the non-aqueous electrolyte secondary battery according to item 8.
Item 10. Use of a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and a binder containing polyvinyl alcohol for a non-aqueous electrolyte secondary battery electrode.

According to the present invention, it is possible to provide a binder for an electrode having sufficient binding power and capable of reducing the resistance of a non-aqueous electrolyte secondary battery. Further, according to the present invention, an electrode mixture for a non-aqueous electrolyte secondary battery including the binder, an electrode for a non-aqueous electrolyte secondary battery using the electrode mixture, and a non-aqueous electrolyte secondary battery including the electrode And an electric device provided with the secondary battery.

Hereinafter, the binder for non-aqueous electrolyte secondary battery electrodes, the electrode mixture for non-aqueous electrolyte secondary batteries, the electrode for non-aqueous electrolyte secondary batteries, the non-aqueous electrolyte secondary battery, and the electric device of the present invention will be described in detail.

In the present invention, “(meth) acrylic acid” means “acrylic acid” and / or “methacrylic acid”, and expressions similar thereto are also the same.

<Binder for non-aqueous electrolyte secondary battery electrode>
The binder for a non-aqueous electrolyte secondary battery electrode of the present invention (hereinafter sometimes referred to as "the binder of the present invention") is a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, It is characterized in that it contains polyvinyl alcohol. By using the binder for the non-aqueous electrolyte secondary battery electrode of the present invention for the electrode of the non-aqueous electrolyte secondary battery, the binder can exhibit sufficient binding power, and the resistance of the non-aqueous electrolyte secondary battery can be reduced.

[Copolymer of vinyl alcohol and neutralized alkali metal of ethylenically unsaturated carboxylic acid]
A copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid (hereinafter sometimes simply referred to as "copolymer") means vinyl alcohol and ethylene as a monomer (monomer) component. It means a copolymer obtained by copolymerizing an aliphatic unsaturated carboxylic acid alkali metal neutralized product. The said copolymer is, for example, in a mixed solvent of an aqueous organic solvent and water in the presence of an alkali containing alkali metal, and a precursor obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester. Can be obtained by saponification. That is, although vinyl alcohol itself is unstable and can not be used directly as a monomer, the copolymer produced by saponifying a polymer obtained using a vinyl ester as a monomer results In this embodiment, vinyl alcohol is copolymerized as a monomer component.

Examples of the vinyl ester include vinyl acetate and vinyl propionate, and vinyl acetate is preferable from the viewpoint that the saponification reaction easily proceeds. A vinyl ester may be used individually by 1 type, and can also be used in combination of 2 or more type.

Examples of the ethylenically unsaturated carboxylic acid ester include methyl ester of (meth) acrylic acid, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester, t-butyl ester and the like, and saponification reaction Methyl acrylate and methyl methacrylate are preferred from the viewpoint that The ethylenically unsaturated carboxylic acid esters may be used alone or in combination of two or more.

Also, if necessary, other ethylenically unsaturated monomers copolymerizable with vinyl ester and ethylenically unsaturated carboxylic acid ester are used in addition to vinyl ester and ethylenically unsaturated carboxylic acid ester, and these are used. It may be copolymerized.

As an example of the saponification reaction, the saponification reaction in the case of 100% saponification with potassium hydroxide is shown below for the precursor obtained by copolymerizing vinyl acetate / methyl acrylate.

The copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid is derived from the monomer of a precursor obtained by random copolymerization of a vinyl ester and an ethylenically unsaturated carboxylic acid ester. And the bond between monomers is a C—C covalent bond. Hereinafter, "a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid" may be simply referred to as a copolymer. Also, “/” in the above formula indicates that random copolymerization is performed.

From the viewpoint that the binder of the present invention exhibits a sufficient binding power and more preferably reduces the resistance of the non-aqueous electrolyte secondary battery, the precursor obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester The molar ratio of vinyl ester to ethylenically unsaturated carboxylic acid ester is preferably 95/5 to 5/95, more preferably 90/10 to 10/90, still more preferably 80/20 to 20/80. By setting the molar ratio to 95/5 to 5/95, the retention of the copolymer obtained after saponification as a binder is further improved.

Therefore, from the viewpoint of the binder of the present invention exhibiting more sufficient binding power and reducing the resistance of the non-aqueous electrolyte secondary battery more suitably, the obtained vinyl alcohol and the alkali metal neutralized with ethylenically unsaturated carboxylic acid The copolymer composition ratio is preferably 95/5 to 5/95, more preferably 90/10 to 10/90, still more preferably 80/20 to 20/80 in molar ratio. By setting the molar ratio to 95/5 to 5/95, the retention as a binder in the electrode mixture can be further improved.

In addition, the total mass (100% by mass) of the monomer forming the copolymer is from the viewpoint of the binder of the present invention exhibiting a sufficient binding power and reducing the resistance of the non-aqueous electrolyte secondary battery more suitably. On the other hand, the total proportion of the vinyl ester and the ethylenically unsaturated carboxylic acid ester is preferably 5% by mass or more, more preferably 20 to 95% by mass, and still more preferably 40 to 95% by mass.

As the ethylenically unsaturated carboxylic acid alkali metal neutralized product according to the present invention, an alkali metal (meth) acrylate neutralized product is preferable from the viewpoint of easy handling at the time of production. Moreover, as an alkali metal of the ethylenically unsaturated carboxylic acid alkali metal neutralized material, lithium, sodium, potassium, rubidium, cesium etc. can be illustrated, Preferably it is potassium and sodium. Particularly preferred ethylenically unsaturated carboxylic acid alkali metal neutralized products are selected from the group consisting of sodium acrylate neutralized products, potassium acrylate neutralized products, sodium methacrylate neutralized products, and potassium methacrylate neutralized products It is at least one kind.

A precursor obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester (hereinafter sometimes referred to simply as a precursor) is a dispersant containing a polymerization catalyst from the viewpoint of obtaining a powdery precursor. It is preferable that the polymer particles be obtained by a suspension polymerization method, in which an aqueous solution is polymerized in a state in which monomers consisting mainly of a vinyl ester and an ethylenically unsaturated carboxylic acid ester are suspended to obtain polymer particles.

Examples of the polymerization catalyst include organic peroxides such as benzoyl peroxide and lauryl peroxide, and azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile. Of these, lauryl peroxide is preferable. .

The addition amount of the polymerization catalyst is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and more preferably 0.1 to 3% by mass with respect to the total mass (100% by mass) of the monomers. Is more preferred. If the amount is less than 0.01% by mass, the polymerization reaction may not be completed. If the amount is more than 5% by mass, the binding effect of the finally obtained copolymer as a binder may not be sufficient.

As a dispersing agent at the time of carrying out polymerization, for example, polyvinyl alcohol (partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol), poly (meth) acrylic acid and salts thereof, polyvinyl pyrrolidone, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxy Examples thereof include water-soluble polymers such as propyl cellulose, and water-insoluble inorganic compounds such as calcium phosphate and magnesium silicate. These dispersants may be used alone or in combination of two or more.

The amount of the dispersant used is preferably 0.01 to 10% by mass, preferably 0.05 to 5% by mass based on the total mass (100% by mass) of the monomers, although it depends on the kind of the monomer to be used. % By mass is more preferred.

Furthermore, water-soluble salts of alkali metals and alkaline earth metals can also be added in order to adjust the surfactant effect of the dispersant. Examples of water-soluble salts include sodium chloride, potassium chloride, calcium chloride, lithium chloride, sodium sulfate, potassium sulfate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, trisodium phosphate, tripotassium phosphate and the like. These water-soluble salts may be used alone or in combination of two or more.

The amount of the water-soluble salt used is usually 0.01 to 10% by mass based on the mass of the aqueous dispersant solution.

The temperature for polymerizing the monomer is preferably -20 ° C to + 20 ° C, more preferably -10 ° C to + 10 ° C, with respect to the 10 hour half-life temperature of the polymerization catalyst. If the temperature for polymerizing the monomer is less than -20 ° C with respect to the 10 hour half-life temperature of the polymerization catalyst, the polymerization reaction may not be completed, and if it exceeds + 20 ° C, vinyl alcohol and ethylenic unsaturation obtained. In some cases, the binding effect as a binder for a copolymer with an alkali metal carboxylate is not sufficient.

The time for polymerizing the monomers is usually several hours to several tens of hours.

After completion of the polymerization reaction, the precursor is separated by a method such as centrifugation, filtration and the like to obtain a water-containing cake. The obtained water-containing cake-like precursor can be used as it is or, if necessary, dried for saponification reaction.

The number average molecular weight of the precursor can be determined using a polar solvent such as DMF with a molecular weight measurement apparatus equipped with a GFC column (manufactured by Shodex, OHpak) or the like. As such a molecular weight measuring device, for example, 2695 manufactured by Waters, RI detector 2414 can be mentioned.

The number average molecular weight of the precursor is preferably 10,000 to 10,000,000, and more preferably 50,000 to 5,000,000. By setting the number average molecular weight of the precursor within the range of 10,000 to 10,000,000, the binding ability is improved as a binder, and in particular, when used as an aqueous binder, the thickness can be easily controlled.

The saponification reaction can be carried out, for example, in the presence of an alkali containing an alkali metal, in an aqueous organic solvent alone, or in a mixed solvent of an aqueous organic solvent and water. A well-known thing can be used as an alkali containing the alkali metal used for saponification reaction. An alkali metal hydroxide is preferably used as the alkali, and sodium hydroxide and potassium hydroxide are more preferably used from the viewpoint of high reactivity.

The amount of the alkali used is preferably 60 to 140 mol%, more preferably 80 to 120 mol%, with respect to the total number of moles of the monomer. If the amount of alkali used is less than 60 mol%, saponification may be insufficient, and even if it is used more than 140 mol%, no further effect is obtained and it is not economical. The degree of saponification in the saponification reaction of the precursor is preferably 90 to 100%, and more preferably 95 to 100%. The solubility to water can be improved by making saponification degree into 90% or more.

In the copolymer of the present invention, the free carboxylic acid (COOH) group derived from the ethylenically unsaturated carboxylic acid ester is hardly present regardless of the amount of the alkali used. By the absence of the carboxylic acid group, the prepared slurry-like electrode mixture has an appropriate viscosity, and coating properties and storage stability can be improved.

As a solvent for the saponification reaction, it is preferable to use only an aqueous organic solvent or a mixed solvent of an aqueous organic solvent and water. Examples of the aqueous organic solvent include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol, ketones such as acetone and methyl ethyl ketone, and mixtures thereof. Among these, lower alcohols are preferable, and methanol and ethanol are particularly preferable because a copolymer having excellent thickening effect and excellent resistance to mechanical shear can be obtained. The aqueous organic solvent may be used alone or in combination of two or more.

The weight ratio (aqueous organic solvent: water) in the case of using a mixed solvent of an aqueous organic solvent and water is preferably 2: 8 to 10: 0, and more preferably 3: 7 to 8: 2. If it is out of the range of 2: 8 to 10: 0, the solvent affinity of the precursor or the solvent affinity of the copolymer after saponification may be insufficient, and the saponification reaction may not proceed sufficiently. When the ratio of the aqueous organic solvent is less than 2: 8, it becomes easy to thicken in the saponification reaction, and it becomes difficult to industrially obtain a copolymer. When the water-containing cake precursor is used as it is for the saponification reaction, the mass ratio of the mixed solvent includes water of the water-containing cake precursor.

The temperature of the saponification reaction of the precursor is preferably 20 to 80 ° C., and more preferably 20 to 60 ° C. When the saponification reaction is carried out at a temperature lower than 20 ° C., the reaction may not be completed, and in the case of a temperature exceeding 80 ° C., the inside of the reaction system may be thickened and it may be difficult to stir.

The time for the saponification reaction is usually about several hours.

When the saponification reaction is completed, a paste or slurry-like copolymer dispersion is usually formed. The dispersion is solid-liquid separated by a method such as centrifugal separation or filtration, washed with a lower alcohol such as methanol, and dried to obtain spherical single particles or aggregated particles in which spherical particles are aggregated. A copolymer with a saturated carboxylic acid alkali metal neutralized product can be obtained.

After the saponification reaction, after the acid treatment of the copolymer using an acid such as an inorganic acid such as hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid; an organic acid such as formic acid, acetic acid, oxalic acid or citric acid, lithium hydroxide Different alkali metals such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, francium hydroxide, etc. (that is, different alkali metals), vinyl alcohol and ethylenic unsaturated carboxylic acid alkali Copolymers of metal-neutralized products can also be obtained.

As the conditions for drying the liquid-containing copolymer, it is usually preferable to dry at a temperature of 30 to 120 ° C. under normal pressure or reduced pressure. The drying time is usually several hours to several tens of hours, depending on the pressure and temperature at the time of drying.

From the viewpoint of the binder of the present invention exhibiting a sufficient binding power and reducing the resistance of the non-aqueous electrolyte secondary battery more suitably, the obtained vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product The volume average particle diameter of the copolymer is preferably 1 to 200 μm, and more preferably 10 to 100 μm. A binding effect is more preferably obtained at 1 μm or more, and by making the thickness 200 μm or less, the thickening liquid becomes more uniform and a preferable binding effect is obtained. The volume average particle size of the copolymer can be determined by installing a batch cell (SALD-BC, manufactured by Shimadzu Corporation) in a laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation), and using 2-propanol as a dispersion solvent or the like. It is the value measured using methanol.

The liquid-containing copolymer is dried, and when the volume-average particle size of the obtained copolymer exceeds 200 μm, the volume-average particle size is 1 μm or more by grinding using a conventionally known grinding method such as mechanical milling treatment. It can be adjusted to 200 μm or less.

Mechanical milling is a method of applying an external force such as impact, tension, friction, compression, or shear to the obtained copolymer, and as a device therefor, a rolling mill, a vibration mill, a planetary mill, a rocking mill Horizontal mill, attritor mill, jet mill, crusher, homogenizer, fluidizer, paint shaker, mixer and the like. For example, in a planetary mill, the copolymer and the ball are put together in a container, and the mechanical energy generated by simultaneously rotating and revolving the copolymer grinds or mixes the copolymer. According to this method, it is crushed to nano order.

As a thickening effect of the copolymer of the vinyl alcohol and the ethylenically unsaturated carboxylic acid alkali metal neutralized product according to the present invention, from the viewpoint of the easiness of coating of the produced electrode mixture, the above-mentioned copolymer The viscosity of an aqueous solution containing 1% by mass (1% by mass aqueous solution) is preferably 20 to 10000 mPa · s, more preferably 50 to 10000 mPa · s, and still more preferably 50 to 5000 mPa · s. When the viscosity is 20 mPa · s or more, a slurry-like electrode mixture having a preferable viscosity can be obtained, and the coatability can be facilitated. In addition, the dispersibility of the active material and the conductive additive in the mixture becomes good. If the viscosity is 10000 mPa · s or less, the viscosity of the prepared mixture is not too high, and it becomes easier to thinly and uniformly coat the current collector. The viscosity of the 1% by mass aqueous solution was measured using a rotational viscometer (model DV-I +) manufactured by BROOK FIELD, spindle No. 5 and 50 rpm (liquid temperature 25 ° C.).

The binder of the present invention exerts sufficient binding power, and from the viewpoint of lowering the resistance of the non-aqueous electrolyte secondary battery more suitably, vinyl alcohol and alkali metal of ethylenically unsaturated carboxylic acid in the binder of the present invention are neutralized The proportion of the copolymer with the substance is preferably 5% by mass or more, more preferably 20% by mass to 95% by mass, and still more preferably 40% by mass to 95% by mass.

[Polyvinyl alcohol]
In the binder for a non-aqueous electrolyte secondary battery electrode of the present invention, the polyvinyl alcohol preferably has a degree of saponification of 75% or more, more preferably 90% or more, from the viewpoint of solubility in water. Furthermore, as the polyvinyl alcohol preferably used, the degree of polymerization is preferably about 100 to about 3,000 from the viewpoint of handling.

The polyvinyl alcohol preferably has a number average molecular weight of 1,000 to 5,000,000, from the viewpoint of achieving a sufficient binding ability of the binder of the present invention and suitably reducing the resistance of the non-aqueous electrolyte secondary battery. From the viewpoint of providing a viscosity that is easy to handle when applying the electrode mixture, 4,000 to 1,000,000 is more preferable.

The number average molecular weight of polyvinyl alcohol is a value measured by a molecular weight measurement apparatus equipped with a GFC column, like the number average molecular weight of the precursor.

Polyvinyl alcohol can be produced by a known method, for example, can be produced by polymerizing a vinyl ester in the presence of a catalyst and saponifying in the presence of a catalyst such as an acid or an alkali. Moreover, as polyvinyl alcohol, commercially available products, such as product name "GOOSENOL" series (made by Japan Synthetic Chemical Industry Co., Ltd.) and product name "Kuraray poval" series (made by Kuraray), can also be used, for example.

In the binder of the present invention, the content of polyvinyl alcohol is relative to the total mass of the binder, from the viewpoint that the binder of the present invention exerts a more sufficient binding power and lowers the resistance of the non-aqueous electrolyte secondary battery more suitably. Preferably it is 1 mass% or more, More preferably, it is 1 to 60 mass%, More preferably, it is 1 to 40 mass%.

In the binder of the present invention, the mass ratio of the copolymer to the polyvinyl alcohol (from the viewpoint of reducing the resistance of the non-aqueous electrolyte secondary battery more suitably, the binder of the present invention exhibits a sufficient binding power, The copolymer / polyvinyl alcohol) is preferably 95/5 to 70/30, more preferably 95/5 to 65/35, still more preferably 95/5 to 60/40. By setting the mass ratio to 95/5 to 70/30, the resistance at the electrode tends to be further reduced, and the deterioration of the cycle life characteristics due to the insufficient binding power tends to be suppressed.

[Other ingredients]
The binder for a non-aqueous electrolyte secondary battery electrode of the present invention may further contain other components in addition to a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and polyvinyl alcohol. . As another component, what is mix | blended with the well-known binder for nonaqueous electrolyte secondary battery electrodes is mentioned. Specific examples of other components include: carboxymethylcellulose (CMC), acrylic resin, sodium polyacrylate, sodium alginate, polyimide (PI), polyamide, polyamide imide, polyacrylic, styrene butadiene rubber (SBR), ethylene vinyl acetate copolymer Polymer (EVA) is mentioned. Among these, acrylic resin, sodium polyacrylate, sodium alginate, polyamide, polyamide imide, and polyimide are suitably used, and acrylic resin is particularly suitably used. The other components may be used alone or in combination of two or more.

The polyalkylene oxide may not be contained in the binder for a non-aqueous electrolyte secondary battery electrode of the present invention. That is, in one embodiment of the binder for non-aqueous electrolyte secondary battery electrodes of the present invention, the polyalkylene oxide is not contained (the content of the polyalkylene oxide is 0% by mass). Examples of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polybutylene oxide, ethylene oxide-propylene oxide copolymer, ethylene oxide-butylene oxide copolymer, and propylene oxide-butylene oxide copolymer.

In the binder of the present invention, the proportion of the other components is preferably less than 80% by mass from the viewpoint that the binder of the present invention exhibits a sufficient binding power and more suitably reduces the resistance of the non-aqueous electrolyte secondary battery. More preferably, it is 50 mass% or less, More preferably, it is 20 mass% or less.

In the binder of the present invention, the vinyl alcohol and the alkali metal of the ethylenically unsaturated carboxylic acid are neutralized in the binder of the present invention from the viewpoint that the binder of the present invention exhibits a sufficient binding power and lowers the resistance of the nonaqueous electrolyte secondary battery more suitably The total content of the copolymer with the polymer and the polyvinyl alcohol is preferably 20 to 100% by mass with respect to the total mass of the binder.

The binder for non-aqueous electrolyte secondary battery electrodes of the present invention can be suitably used as a water-based binder (that is, a water-based binder for non-aqueous electrolyte secondary battery electrodes).

<Electrode mix for non-aqueous electrolyte secondary battery>
The electrode mixture for a non-aqueous electrolyte secondary battery of the present invention comprises the binder for a non-aqueous electrolyte secondary battery electrode of the present invention, an electrode active material (a positive electrode active material and a negative electrode active material), and a conductive additive as essential components. And an electrode mixture used for producing an electrode for a non-aqueous electrolyte secondary battery.

The content of the binder of the present invention is 100 wt% of the total of the electrode active material, the conductive additive, and the binder, from the viewpoint of exhibiting a sufficient binding power and suitably reducing the resistance of the non-aqueous electrolyte secondary battery. The amount is preferably 0.5 to 40 parts by mass, more preferably 1 to 25 parts by mass, and still more preferably 1.5 to 10 parts by mass with respect to parts. From the same viewpoint, the content of the binder of the present invention in the electrode mixture of the present invention is preferably 0.5 to 40% by mass, more preferably 1 to 25% by mass, and still more preferably 1.5 to 10%. %. By setting the content to 0.5% by mass or more, deterioration of cycle life characteristics due to insufficient binding power and aggregation due to insufficient viscosity of the slurry tend to be suppressed. On the other hand, by setting the content to 40% by mass or less, a high capacity tends to be obtained at the time of charge and discharge of the battery.

The electrode mixture of the present invention can be produced by a known method using the binder of the present invention. For example, the electrode active material, the conductive aid, the binder of the present invention, and the dispersion aid (if necessary) And water to form a paste-like slurry. The timing of adding water is not particularly limited, and may be added by dissolving the binder of the present invention in water in advance, an electrode active material, a conductive aid, a dispersing aid (if necessary), and the present invention After mixing the binder in the solid state, water may be added thereto.

The amount of water used is, for example, preferably 40 to 2000 parts by mass, more preferably 50 to 1000 parts by mass with respect to a total of 100 parts by mass of the electrode active material, the conductive auxiliary agent, and the binder of the present invention. . In addition, there exists a tendency which the handleability of the electrode mixture (slurry) of this invention improves more by making the usage-amount of water into the said range.

[Positive electrode active material]
As a positive electrode active material, the positive electrode active material used in this technical field can be used. For example, lithium iron phosphate (LiFePO ₄ ), lithium manganese phosphate (LiMnPO ₄ ), lithium cobalt phosphate (LiCoPO ₄ ), iron pyrophosphate (Li ₂ FeP ₂ O ₇ ), lithium cobaltate (LiCoO ₂ ), spinel Type lithium manganate composite oxide (LiMn ₂ O ₄ ), lithium manganate composite oxide (LiMnO ₂ ), lithium nickelate composite oxide (LiNiO ₂₎ , lithium niobate composite oxide (LiNbO ₂ ), lithium ferrate composite oxides (LiFeO _2), magnesium lithium composite oxide (LiMgO _2), lithium composite oxide of calcium acid (LiCaO _2), cuprate lithium composite oxide (LiCuO _2), lithium zincate complex oxide (LiZnO ₂ ), Lithium molybdate composite oxide (LiMoO ₂ ), tantalum Lithium oxalate composite oxide (LiTaO ₂ ), lithium tungstate composite oxide (LiWO ₂ ), lithium-nickel-cobalt-aluminum composite oxide (LiNi _0.8 Co _0.15 Al _0.05 O ₂ ), lithium-nickel-cobalt-manganese complex oxide _{((LiNi x Co y Mn 1} -xy O 2) 0 <x <1,0 <y <1, x + y <1), Li excess type nickel - cobalt - manganese complex oxide, manganese oxide nickel (LiNi _0.5 Mn _1.5 O ₄ ), manganese oxide (MnO ₂ ), vanadium oxides, sulfur oxides, silicate oxides, etc. are preferably used. These can be used singly or in combination of two or more.

[Anode active material]
As the negative electrode active material, a negative electrode active material used in the present technical field can be used. For example, a material that can occlude and release a large amount of lithium ions, such as a carbon material, silicon (Si), tin (Sn), lithium titanate, or the like can be used. If it is such a material, it is possible to exhibit the effect of the present embodiment regardless of any one of a simple substance, an alloy, a compound, a solid solution, and a composite active material containing a silicon-containing material and a tin-containing material. As said carbon material, crystalline carbon, amorphous carbon, etc. can be used. Examples of crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical or fibrous natural graphite or artificial graphite. Examples of amorphous carbon include soft carbon (easy-carbonized graphite) or hard carbon (hard-to-carbonize graphite), mesophase pitch carbide, calcined coke and the like. As a silicon-containing material, Si, SiOx (0.05 <x <1.95), or B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Nb, or any of these can be used. An alloy, a compound, a solid solution, or the like in which a part of Si is substituted by at least one or more elements selected from the group consisting of Ta, V, W, Zn, C, N, and Sn can be used. These can be referred to as silicon or silicon compounds. As the tin-containing material, Ni ₂ Sn ₄ , Mg ₂ Sn, SnO _x (0 <x <2), SnO ₂ , SnSiO ₃ , LiSnO or the like can be applied.
One of these materials may be used alone, or two or more of these materials may be used in combination. Among these, as the negative electrode active material, graphite is preferable. By using the binder of the present invention, even when graphite is used as the negative electrode active material, the binder exhibits sufficient binding power, and the resistance of the non-aqueous electrolyte secondary battery can be suitably reduced.

A composite obtained by mixing silicon and a silicon compound as the first negative electrode active material, a carbon material as the second negative electrode active material, and the first and second negative electrode active materials may be used as the negative electrode active material. At this time, the mixing ratio of the first and second negative electrode active materials is preferably 5/95 to 95/5 by mass. The carbon material may be any carbon material used in the technical field, and typical examples thereof include the above-mentioned crystalline carbon and amorphous carbon.

The method for producing the negative electrode active material may be any method as long as it is possible to uniformly disperse the active material complex in which the first negative electrode active material and the second negative electrode active material are mixed. As a specific method of manufacturing a negative electrode active material, a method of mixing a first negative electrode active material and a second negative electrode active material in a ball mill can be mentioned. In addition, for example, a method of supporting the second negative electrode active material precursor on the particle surface of the first negative electrode active material and carbonizing the precursor by the heat treatment method may be mentioned. The second negative electrode active material precursor may be any carbon precursor that can be a carbon material by heat treatment, and examples thereof include glucose, citric acid, pitch, tar, binder materials (for example, polyvinylidene fluoride, carboxymethylcellulose, acrylic) Resin, sodium polyacrylate, sodium alginate, polyimide, polytetrafluoroethylene, polyamide, polyamide imide, polyacryl, styrene butadiene rubber, polyvinyl alcohol, ethylene vinyl acetate copolymer and the like can be mentioned. Commercially available products of these negative electrode active materials are readily available.

In the above heat treatment method, the carbon precursor is carbonized by heat treatment at 600 to 4000 ° C. in a non-oxidizing atmosphere (a non-oxidizable atmosphere such as a reducing atmosphere, an inert atmosphere, or a reduced pressure atmosphere). It is a way to get.

[Conduction agent]
The conductive aid can use the conductive aid used in the technical field, and carbon powder is preferable. As carbon powder, for example, acetylene black (AB), ketjen black (KB), graphite, carbon fiber, carbon tube, graphene, amorphous carbon, hard carbon, soft carbon, glassy carbon, carbon nanofiber, carbon nanotube (CNT) and the like.

The amount of the conductive aid used is preferably 0.1 to 30% by mass, more preferably 0.5 to 10% by mass, with respect to 100 parts by mass in total of the electrode active material, the conductive auxiliary and the binder. 5 mass% is more preferable. If the amount of the conductive aid used is less than 0.1% by mass, the conductivity of the electrode may not be sufficiently improved. If the amount of the conductive aid exceeds 30% by mass, the proportion of the electrode active material relatively decreases, and it is difficult to obtain a high capacity at the time of charge and discharge of the battery, and the surface area is small because it is smaller than the electrode active material There is a possibility that the amount of binder used may increase.

[Dispersion aid]
The electrode mixture of the present invention may further contain a dispersion aid. By including the dispersion aid, the dispersibility of the electrode active material and the conductive aid in the electrode mixture becomes high. As the dispersion aid, an organic acid having a molecular weight of 100,000 or less and soluble in an aqueous solution of pH 7 to 13 is preferable. Among these organic acids, it is preferable to contain a carboxyl group and at least one of a hydroxy group, an amino group or an imino group. As specific examples, compounds having a carboxyl group and a hydroxy group such as lactic acid, tartaric acid, citric acid, malic acid, glycolic acid, thaltronic acid, glucuronic acid, humic acid and the like; glycine, alanine, phenylalanine, 4-aminobutyric acid, leucine Compounds having a carboxyl group and an amino group such as isoleucine and lysine; compounds having a plurality of carboxyl groups and an amino group such as glutamic acid and aspartic acid; proline, 3-hydroxyproline, 4-hydroxyproline, pipecoline Compounds having a carboxyl group such as an acid and an imino group; compounds having a carboxyl group such as glutamine, asparagine, cysteine, histidine and tryptophan and a functional group other than a hydroxyl group and an amino group may be mentioned. Among these, glucuronic acid, humic acid, glycine, aspartic acid and glutamic acid are preferable from the viewpoint of availability.

The molecular weight of the dispersion aid is preferably 100,000 or less from the viewpoint of solubility in water in the case of an aqueous binder. When the molecular weight exceeds 100,000, the hydrophobicity of the molecule becomes strong, and the uniformity of the slurry may be impaired.

<Electrode for non-aqueous electrolyte secondary battery>
The electrode for a non-aqueous electrolyte secondary battery of the present invention uses the electrode mixture of the present invention (that is, uses the electrode for a non-aqueous electrolyte secondary battery of the present invention), and applies the method used in the technical field. Can be produced. For example, it can be produced by providing an electrode mixture on a current collector. More specifically, it can be produced, for example, by applying (and optionally drying) the electrode mixture on a current collector.

When the electrode of the present invention is a positive electrode, examples of materials constituting the current collector include C, Cu, Ni, Fe, V, Nb, Ti, Cr, Mo, Ru, Rh, Ta, W, Os, Ir Conductive materials such as Pt, Au, and AI, and alloys containing two or more of these conductive materials (for example, stainless steel) can be used. The current collector may be one obtained by plating a conductive substance with another conductive substance (for example, one obtained by plating Cu on Fe). From the viewpoints of high electrical conductivity and excellent stability and oxidation resistance in the electrolytic solution, Cu, Ni, stainless steel and the like are preferable as the material constituting the current collector, and Cu and Ni are preferable from the viewpoint of material cost. preferable.

When the electrode of the present invention is a negative electrode, examples of materials constituting the current collector include conductive materials such as C, Ti, Cr, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Au, Al, etc. A substance, an alloy containing two or more of these conductive substances (for example, stainless steel) may be used. From the viewpoint of high electrical conductivity and excellent stability in the electrolytic solution and oxidation resistance, the material constituting the current collector is preferably C, Al, stainless steel, etc., and from the viewpoint of material cost, Al is preferable.

As a shape of the current collector, for example, a foil-like substrate, a three-dimensional substrate or the like can be used. However, when a three-dimensional substrate (foam metal, mesh, woven fabric, non-woven fabric, expand, etc.) is used, an electrode with a higher capacity density is obtained, and the high rate charge / discharge characteristics also become good.

<Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery of the present invention (non-aqueous electrolyte secondary battery including at least the non-aqueous electrolyte secondary battery electrode of the present invention) can be produced using the electrode of the present invention. The non-aqueous electrolyte secondary battery of the present invention may be provided with the non-aqueous electrolyte secondary battery electrode of the present invention as either or both of the positive electrode and the negative electrode. As a non-aqueous electrolyte secondary battery, a lithium ion secondary battery is preferable. As a method of manufacturing the non-aqueous electrolyte secondary battery of the present invention, a general method used in the technical field can be used.

Among the non-aqueous electrolyte secondary batteries of the present invention, since lithium ion secondary batteries contain lithium ions, lithium salts are preferably used as the electrolyte. Examples of the lithium salt include lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium trifluoromethanesulfonate imide and the like. An electrolyte can be used individually by 1 type, and can also be used in combination of 2 or more type.

As an electrolytic solution of the battery, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone and the like can be used. An electrolyte solution can also be used individually by 1 type, and can also be used in combination of 2 or more type. In particular, propylene carbonate alone, a mixture of ethylene carbonate and diethyl carbonate, or γ-butyrolactone alone is preferable. The mixing ratio of the mixture of ethylene carbonate and diethyl carbonate described above can be arbitrarily adjusted within the range of 10 to 90% by volume of one component.

<Electric equipment>
The electric device of the present invention is an electric device provided with at least the non-aqueous electrolyte secondary battery of the present invention. That is, the electric device according to the present invention is an electric device using at least the non-aqueous electrolyte secondary battery of the present invention as a power source.

The electric device of the present invention includes, for example, air conditioners, washing machines, televisions, refrigerators, personal computers, tablets, smartphones, personal computer keyboards, monitors, printers, mice, hard disks, personal computer peripherals, irons, clothes dryers, transceivers, blowers, Music recorder, music player, oven, range, warm air heater, car navigation system, flashlight, humidifier, portable karaoke machine, dry battery, air purifier, game machine, sphygmomanometer, coffee mill, coffee maker, kotatsu, copy machine, disc Changer, Radio, Shaver, Juicer, Shredder, Water Filter, Lighting Fixture, Dishware Dryer, Cooker, Trouser Press, Vacuum Cleaner, Weight Scale, Electric Carpet, Rice Cooker, Electric Pot, Electronic Dictionary, Electronic Notebook, Electromagnetic Cooker , Calculator, electric cart, electric car Child, electric tool, electric toothbrush, hearth, clock, intercom, air circulator, electric shock insecticide, hot plate, toaster, water heater, crusher, soldering iron, video camera, video deck, facsimile, futon dryer, mixer , Sewing machines, rice cookers, water coolers, electronic musical instruments, motorcycles, toys, lawn mowers, bicycles, automobiles, hybrid vehicles, plug-in hybrid vehicles, railways, ships, planes, emergency storage batteries, and the like.

EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to these examples.

<Production of Copolymer A>
Copolymer A was produced by the following steps 1 to 3.

(Step 1: Synthesis of vinyl ester and ethylenically unsaturated carboxylic acid ester copolymerized precursor (precursor))
Water (768 g) and anhydrous sodium sulfate (12 g) were charged into a _2- liter reaction vessel equipped with a stirrer, thermometer, N ₂ gas introduction pipe, reflux condenser and dropping funnel, and N ₂ gas was blown to deoxidize the system. Subsequently, 1 g of partially saponified polyvinyl alcohol (saponification degree 88%) and 1 g of lauryl peroxide were charged, and after raising the internal temperature to 60 ° C., 104 g (1.209 mol) of methyl acrylate and 155 g (1 802 mol) was added dropwise over 4 hours by a dropping funnel. Thereafter, the internal temperature was maintained at 65 ° C. for 2 hours. Next, the solid content was separated by filtration to obtain 288 g of a precursor (10.4 mass% water content). The obtained precursor was dissolved in DMF and filtered through a filter, and the molecular weight of the precursor in the filtrate was measured using a molecular weight measuring apparatus (2695 manufactured by Waters, RI detector 2414). The number average molecular weight calculated in terms of standard polystyrene was 1,880,000.

(Step 2: Synthesis of copolymer (copolymer) of vinyl alcohol and alkali metal neutralized with ethylenically unsaturated carboxylic acid)
In a reaction vessel similar to Step 1, 450 g of methanol, 420 g of water, 132 g (3.3 mol) of sodium hydroxide and 288 g of the precursor obtained in Step 1 (10.4 mass% water content) are charged. Saponification reaction was performed for 3 hours. After completion of the saponification reaction, the obtained copolymer is washed with methanol, filtered, dried at 70 ° C. for 6 hours, vinyl ester / ethylenically unsaturated carboxylic acid ester copolymer (vinyl alcohol and ethylenic unsaturated carboxylic acid) A copolymer with an acid alkali metal neutralized product, alkali metal sodium, 98.8% saponification degree) 193 g was obtained. The volume average particle size of the obtained copolymer was 180 μm.

(Step 3: Grinding of copolymer (copolymer) of vinyl alcohol and alkali metal neutralized with ethylenically unsaturated carboxylic acid)
193 g of the copolymer obtained in step 2 was pulverized by a jet mill (LJ, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain 173 g of a finely powdered copolymer (copolymer A). The particle diameter of the obtained copolymer A was measured by a laser diffraction type particle size distribution measuring device (SALD-7100, manufactured by Shimadzu Corporation), and the volume average particle diameter was 39 μm.

<Preparation of a binder, an electrode mixture, and an electrode>
Example 1
2.7 parts by mass of the copolymer A obtained above and 0.3 parts by mass of polyvinyl alcohol (Kuraray Co., Ltd., Kuraray Co., Ltd., Kurare Pover 105, number average molecular weight 22,000) dissolved in 50 parts by mass of water are used as binders. An aqueous solution of (the binder composition) was obtained. Next, 96.5 parts by mass of artificial graphite (manufactured by Hitachi Chemical Co., Ltd., MAG-D) as an electrode active material, and acetylene black (AB) as a conductive additive (Denka Black (registered trademark, manufactured by Denki Kagaku Kogyo Co., Ltd.) 0.5 parts by mass of a trade mark) was added to the above aqueous binder solution and kneaded. Furthermore, 70 parts by mass of water for viscosity adjustment was added and kneaded to prepare a slurry-like negative electrode mixture. The obtained negative electrode mixture is applied on a 10 μm-thick electrolytic copper foil and dried, and then the electrolytic copper foil and the coating film are closely bonded by a roll press machine (manufactured by Ono Roll Co., Ltd.). Heat treatment (under reduced pressure, at 140 ° C. for 3 hours or more) to prepare a negative electrode. The thickness of the active material layer in the obtained negative electrode was 100 μm, and the capacity density of the negative electrode was 3.0 mAh / cm ² .

(Example 2)
The procedure of Example 1 was repeated, except that 2.4 parts by mass of the copolymer A and 0.6 parts by mass of polyvinyl alcohol (Kuraray Co., Ltd., KURARAY POVAL 105, number average molecular weight 22,000) were used. In the same manner as in Example 1, a negative electrode was produced. The thickness of the active material layer in the obtained negative electrode was 101 μm, and the capacity density of the negative electrode was 3.0 mAh / cm ² .

(Comparative example 1)
A negative electrode was produced in the same manner as in Example 1 except that 3.0 parts by mass of the copolymer A and no polyvinyl alcohol were used in Example 1. The thickness of the active material layer in the obtained negative electrode was 99 μm, and the capacity density of the negative electrode was 3.0 mAh / cm ² .

(Comparative example 2)
Example 1 is the same as example 1 except that 3.0 parts by mass of polyvinyl alcohol (Kuraray Co., Ltd., KURARAY POVAL 105, number average molecular weight 22,000) is used and 3.0 parts by mass and copolymer A is not used. Then, a negative electrode was produced. The thickness of the active material layer in the obtained negative electrode was 102 μm, and the capacity density of the negative electrode was 3.0 mAh / cm ² .

(Peeling test)
The peeling strength test of the coating film (negative electrode active material layer) with respect to the current collector in the negative electrode obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was performed. The negative electrode is cut out to a width of 80 mm × 15 mm, and an adhesive tape is attached to the surface (negative electrode active material layer side), then attached to a stainless steel plate with double-sided tape to fix the negative electrode (collector side). It was a sample. 180 degree peel test of negative electrode to stainless steel plate with tensile tester (small desktop tester EZ-Test, manufactured by Shimadzu Corporation) for this evaluation sample (180 of adhesive tape to negative electrode fixed to stainless steel plate) Degree peeling test) was performed, and the peeling strength between the active material layer and the current collector in the negative electrode was measured. Table 1 shows the evaluation results of the peel test (peel strength).

(Electrode strength)
The electrode strength ("electrode strength") depending on the presence or absence of peeling, detachment, or chipping of the active material layer when the electrodes obtained in Examples 1 and 2 and Comparative Examples 1 and 2 are punched to a size of 11 mmφ with a punching machine. (Referred to as Table 2 shows the evaluation results of the electrode strength.

O (excellent in strength): Among 10 randomly punched out electrodes, 2 or less sheets in which any of peeling, falling off or chipping of the active material layer was confirmed by visual judgment.
Δ (Slightly superior in strength): 10 out of 10 randomly punched electrodes, 3 to 5 of which the peeling, falling off or chipping of the active material layer was confirmed by visual judgment.
X (poor strength): Of 10 sheets of the electrode randomly punched out, 6 or more sheets in which any of peeling, falling off or chipping of the active material layer was confirmed by visual observation.

(Assembly of battery)
A coin cell (CR2032) having the negative electrodes obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the following counter electrode, separator, and electrolyte is prepared, and subjected to three cycles of 0.1 C in an environment of 30 ° C. Aging treatment was performed to prepare a sample (coin cell).

・ Counter electrode: Metallic lithium ・ Separator: Glass filter (Advantec Co., Ltd., GA-100)
Electrolyte solution: LiPF ₆ is dissolved at a concentration of 1 mol / L in a solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 1, vinylene carbonate (VC Solution containing 1% by mass of

(Method of evaluating DC resistance)
The coin cells produced as described above having the negative electrode obtained in Examples 1 and 2 and Comparative Example 1 were each charged at 0.2 C under an environment of 30 ° C., 0.2 C, 0.5 C, 1 C, Discharge was performed at each rate of 3C and 5C. The cutoff potential was set to 0 to 1.0 V (vs. Li + / Li) for the above coin cell. From the obtained IV characteristics, the direct current resistance (DC-IR) of the battery was calculated. Table 1 shows direct current resistances of the example and the comparative example. Since the negative electrode obtained in Comparative Example 2 had an electrode strength too low to be suitable as an electrode, the DC resistance was not evaluated.

Claims (10)

1. A binder for a non-aqueous electrolyte secondary battery electrode, comprising a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and polyvinyl alcohol.
2. The non-water according to claim 1, wherein the copolymer composition ratio of the vinyl alcohol and the alkali metal neutralized product of the ethylenically unsaturated carboxylic acid in the copolymer is 95/5 to 5/95 in molar ratio. Binder for electrolyte secondary battery electrode.
3. The binder for a non-aqueous electrolyte secondary battery electrode according to claim 1 or 2, wherein the ethylenically unsaturated carboxylic acid alkali metal neutralized product is a (meth) acrylic acid alkali metal neutralized product.
4. The binder for a non-aqueous electrolyte secondary battery electrode according to any one of claims 1 to 3, wherein a mass ratio of the copolymer to the polyvinyl alcohol is 95/5 to 70/30.
5. An electrode mixture for a non-aqueous electrolyte secondary battery, comprising the electrode active material, a conductive additive, and the binder for a non-aqueous electrolyte secondary battery electrode according to any one of claims 1 to 4.
6. The nonaqueous electrolyte according to claim 5, wherein a content of the binder is 0.5 to 40 parts by mass with respect to a total amount of 100 parts by mass of the electrode active material, the conductive auxiliary agent, and the binder. Electrode mix for secondary batteries.
7. The electrode for non-aqueous electrolyte secondary batteries produced using the electrode mixture for non-aqueous electrolyte secondary batteries of Claim 5 or 6.
8. The nonaqueous electrolyte secondary battery provided with the electrode for nonaqueous electrolyte secondary batteries of Claim 7.
9. An electric device comprising the non-aqueous electrolyte secondary battery according to claim 8.
10. Use of a copolymer of vinyl alcohol and an alkali metal neutralized with an ethylenically unsaturated carboxylic acid, and a binder containing polyvinyl alcohol for a non-aqueous electrolyte secondary battery electrode.