JPWO2019065705A1 - Binder for non-aqueous electrolyte secondary battery electrode, electrode mixture for non-aqueous electrolyte secondary battery, electrode for non-aqueous electrolyte secondary battery, non-aqueous electrolyte secondary battery, and electrical equipment - Google Patents

Abstract

Provided is a binder for an electrode that has sufficient binding force and can reduce the resistance of a non-aqueous electrolyte secondary battery. The binder for a non-aqueous electrolyte secondary battery electrode contains a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and polyvinyl alcohol.

Description

The present invention includes a binder for a non-aqueous electrolyte secondary battery electrode, an electrode mixture for a non-aqueous electrolyte secondary battery containing 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 notebook computers, smartphones, portable game devices, and PDAs, secondary batteries used as a power source to make these devices lighter and can be used for a long time. There is a demand for miniaturization and high energy density.

Particularly in recent years, its use as a power source for vehicles such as electric vehicles and electric motorcycles has been expanding. Secondary batteries used for such vehicle power supplies are required to have not only high energy density but also operation in a wide temperature range, and various non-aqueous electrolyte secondary batteries are available. Proposed.

Conventionally, nickel-cadmium batteries, nickel-hydrogen batteries, etc. have been the mainstream 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 do.

The electrodes of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery are usually a binder solution in which an electrode binder (hereinafter, may be simply referred to as a binder) is dissolved in a solvent, or a binder is dispersed in a dispersion medium. A method such as applying a battery electrode mixture slurry (hereinafter, may be simply referred to as a slurry) in which an active material (electrode active material) and a conductive auxiliary agent are mixed to the slurry, and drying the solvent or dispersion medium. Manufactured by removing with.

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

The negative electrode is made of graphite as an active material, carboxymethyl cellulose (CMC) as a binder, styrene butadiene rubber (SBR), PVDF or polyimide, or carbon black as a conductive auxiliary agent in water or an organic solvent. It is obtained by applying and drying the dispersed negative electrode mixture slurry on a copper foil current collector.

Further, in order to increase the capacity of the lithium ion secondary battery, various graphites have been studied as the negative electrode active material. In particular, it is known that in artificial graphite, the energy capacity as a negative electrode active material changes due to changes in the crystal state due to differences in raw materials and carbonization temperatures (see Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 8-264180 Japanese Unexamined Patent Publication No. 4-188559 Japanese Unexamined Patent Publication No. 10-284882 International Publication No. 2004/049475 Japanese Unexamined Patent Publication No. 10-302799

When various types of graphite are used as the negative electrode active material, PVDF conventionally used as a binder has low binding force and flexibility, so that it is necessary to use a large amount of binder. By using a large amount of binder, the amount of active material is relatively small, the battery capacity is lowered, and the resistance inside the battery is increased. Further, since PVDF dissolves only in an organic solvent, other binders capable of reducing the environmental load have been proposed (see Patent Documents 4 to 5). However, when those binders are used, the performance as a battery is not sufficient.

Further, it is being studied to use styrene-butadiene rubber (SBR) as an aqueous binder which is expected to have an effect of reducing the environmental load without lowering the binding force. However, since SBR having a rubber property, which is an insulator, exists on the surface of the active material, there is a problem that sufficient rate characteristics cannot be obtained and the resistance in the electrode becomes high.

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

The present inventors have diligently studied to solve the above problems. As a result, sufficient binding force is exhibited by using a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylate alkali metal neutralized product and a binder containing polyvinyl alcohol for the electrodes of the non-aqueous electrolyte secondary battery. We have also found that the resistance of non-aqueous electrolyte secondary batteries can be 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 containing a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and polyvinyl alcohol.
Item 2. Item 2. The non-aqueous electrolyte according to Item 1, wherein the copolymer composition ratio of the vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal in the copolymer is 95/5 to 5/95 in terms of molar ratio. Binder for secondary battery electrodes.
Item 3. Item 2. The binder for a non-aqueous electrolyte secondary battery electrode according to Item 1 or 2, wherein the ethylenically unsaturated carboxylic acid alkali metal neutralized product is a (meth) acrylic acid alkali metal neutralized product.
Item 4. Item 2. The binder for a non-aqueous electrolyte secondary battery electrode according to any one of Items 1 to 3, wherein the 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, which comprises an electrode active material, a conductive auxiliary agent, and a binder for a non-aqueous electrolyte secondary battery electrode according to any one of Items 1 to 4.
Item 6. Item 2. 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 of the total amount of the electrode active material, the conductive auxiliary agent, and the binder. Electrode mixture for batteries.
Item 7. An electrode for a non-aqueous electrolyte secondary battery produced by using the electrode mixture for a non-aqueous electrolyte secondary battery according to Item 5 or 6.
Item 8. Item 7. A non-aqueous electrolyte secondary battery provided with the electrode for the non-aqueous electrolyte secondary battery according to Item 7.
Item 9. Item 8. An electric device provided with the non-aqueous electrolyte secondary battery according to Item 8.
Item 10. Use of a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and a binder containing polyvinyl alcohol for a non-aqueous electrolyte secondary battery electrode.

According to the present invention, it is possible to provide an electrode binder having sufficient binding force and capable of lowering 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 containing the binder, an electrode for a non-aqueous electrolyte secondary battery using the electrode mixture, and a non-aqueous electrolyte secondary battery provided with the electrode. , And an electric device equipped with the secondary battery can also be provided.

Hereinafter, the binder for a non-aqueous electrolyte secondary battery electrode, the electrode mixture for a non-aqueous electrolyte secondary battery, the electrode for a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery, and an electric device will be described in detail.

In the present invention, "(meth) acrylic acid" means "acrylic acid" and / or "methacrylic acid", and similar expressions are also applicable.

<Binder for non-aqueous electrolyte secondary battery electrode>
The binder for a non-aqueous electrolyte secondary battery electrode of the present invention (hereinafter, may be referred to as “binder of the present invention”) is a copolymer of vinyl alcohol and an ethylenically unsaturated carboxylic acid alkali metal neutralized product, and It is characterized by containing 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 exerts a sufficient binding force and the resistance of the non-aqueous electrolyte secondary battery can be reduced.

[Copolymer of vinyl alcohol and neutralized ethylenically unsaturated carboxylic acid alkali metal]
The copolymer of vinyl alcohol and ethylenically unsaturated carboxylate alkali metal neutralized product (hereinafter, may be simply referred to as "copolymer") is vinyl alcohol and ethylene as monomer components. It means a copolymer in which a sex-unsaturated carboxylate alkali metal neutralized product is copolymerized. The copolymer is, for example, a precursor obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester in a mixed solvent of an aqueous organic solvent and water in the presence of an alkali containing an alkali metal. It can be obtained by Kenning with. That is, vinyl alcohol itself is unstable and cannot be used directly as a monomer, but the copolymer produced by saponifying the polymer obtained by using vinyl ester as a monomer produces results. As a result, 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 can easily proceed. As the vinyl ester, one kind may be used alone, or two or more kinds may be used in combination.

Examples of the ethylenically unsaturated carboxylic acid ester include methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester, and t-butyl ester of (meth) acrylic acid, and a saponification reaction. Methyl acrylate and methyl methacrylate are preferable from the viewpoint of easy progress. One type of ethylenically unsaturated carboxylic acid ester may be used alone, or two or more types may be used in combination.

Further, if necessary, another ethylenically unsaturated monomer copolymerizable with the vinyl ester and the ethylenically unsaturated carboxylic acid ester is used in addition to the vinyl ester and the ethylenically unsaturated carboxylic acid ester, and these are used. It may be copolymerized.

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

The copolymer of the vinyl alcohol and the ethylenically unsaturated carboxylic acid alkali metal neutralized product is derived from a monomer of a precursor obtained by randomly copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester. It is a compound in which the ester portion of the above is saponified, and the bond between the monomers is a CC covalent bond. Hereinafter, the "copolymer of vinyl alcohol and neutralized ethylenically unsaturated carboxylic acid alkali metal" may be simply referred to as a copolymer. In addition, "/" in the above formula indicates random copolymerization.

In the precursor obtained by copolymerizing a vinyl ester and an ethylenically unsaturated carboxylic acid ester, from the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery. 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, and even more preferably 80/20 to 20/80. By setting the molar ratio to 95/5 to 5/95, the holding power of the copolymer obtained after saponification as a binder is further improved.

Therefore, from the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the obtained vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal are used. The copolymer composition ratio of the above copolymer is preferably 95/5 to 5/95, more preferably 90/10 to 10/90, and further preferably 80/20 to 20/80 in terms of molar ratio. By setting the molar ratio to 95/5 to 5/95, the holding power as a binder in the electrode mixture is further improved.

Further, from the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the total mass of monomers (100% by mass) forming the copolymer is used. On the other hand, the total ratio 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 further preferably 40 to 95% by mass.

As the ethylenically unsaturated carboxylic acid alkali metal neutralized product according to the present invention, a (meth) acrylic acid alkali metal neutralized product is preferable from the viewpoint of easy handling during production. Examples of the alkali metal of the neutralized ethylenically unsaturated carboxylic acid alkali metal include lithium, sodium, potassium, rubidium, cesium and the like, and potassium and sodium are preferable. A particularly preferred ethylenically unsaturated carboxylic acid alkali metal neutralized product is selected from the group consisting of a neutralized product of sodium acrylate, a neutralized product of potassium acrylate, a neutralized product of sodium methacrylate, and a neutralized product of potassium methacrylate. At least one species.

The precursor obtained by copolymerizing a vinyl ester with an ethylenically unsaturated carboxylic acid ester (hereinafter, may be simply referred to as a precursor) is a dispersant containing a polymerization catalyst from the viewpoint of obtaining a powdery precursor. Those obtained by a suspension polymerization method in which a monomer mainly composed of a vinyl ester and an ethylenically unsaturated carboxylic acid ester is suspended in an aqueous solution and polymerized to obtain polymer particles are preferable.

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

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

Examples of the dispersant for carrying out the polymerization include polyvinyl alcohol (partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol), poly (meth) acrylic acid and salts thereof, polyvinylpyrrolidone, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and 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 depends on the type of the monomer used and the like, but 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 monomer. More preferably by mass.

Further, in order to adjust the surface active effect of the dispersant, water-soluble salts of alkali metals and alkaline earth metals can be added. Examples of the water-soluble salt 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 with respect to the mass of the dispersant aqueous solution.

The temperature at which the monomer is polymerized 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 at which the monomer is polymerized 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, the obtained vinyl alcohol and ethylenically unsaturated The binding effect of the copolymer as a binder with the alkali metal carboxylate may not be sufficient.

The time for polymerizing the monomer 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 or filtration to obtain a hydrous cake. The obtained hydrous cake-like precursor can be used as it is or, if necessary, dried and used for the saponification reaction.

The number average molecular weight of the precursor can be determined by a molecular weight measuring device equipped with a GFC column (manufactured by Shodex, OHpak) using a polar solvent such as DMF. Examples of such a molecular weight measuring device include 2695 manufactured by Waters and RI detector 2414.

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

The saponification reaction can be carried out, for example, in the presence of an alkali containing an alkali metal, only in an aqueous organic solvent, or in a mixed solvent of an aqueous organic solvent and water. As the alkali containing an alkali metal used in the saponification reaction, a known alkali can be used. As the alkali, alkali metal hydroxide is preferably used, 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%, based on the total number of moles of the monomers. If the amount of alkali used is less than 60 mol%, the saponification may be insufficient, and even if it is used in excess of 140 mol%, no further effect can be obtained and it is not economical. The degree of saponification during the saponification reaction of the precursor is preferably 90 to 100%, and preferably 95 to 100%. By setting the degree of saponification to 90% or more, the solubility in water can be improved.

In the copolymer of the present invention, almost no free carboxylic acid (COOH) group derived from the ethylenically unsaturated carboxylic acid ester is present regardless of the amount of the alkali used. Since the absence of the carboxylic acid group, the produced slurry-like electrode mixture has an appropriate viscosity, and coatability and storage stability can be improved.

As the 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. Of these, lower alcohols are preferable, and methanol and ethanol are particularly preferable because a copolymer having an excellent thickening effect and excellent resistance to mechanical shear can be obtained. Only one kind of aqueous organic solvent may be used, or two or more kinds may be mixed and used.

The mass ratio (aqueous organic solvent: water) when a mixed solvent of an aqueous organic solvent and water is used 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 during the saponification reaction, and it becomes difficult to obtain a copolymer industrially. When the hydrous cake-like precursor is used as it is in the saponification reaction, the mass ratio of the mixed solvent shall include the water of the hydrous cake-like precursor.

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

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

When the saponification reaction is completed, it usually becomes a dispersion of a paste or a slurry-like copolymer. The dispersion is solid-liquid separated by a method such as centrifugation or filtration, washed with a lower alcohol such as methanol, and dried to form a single spherical particle or agglomerated particles in which the spherical particles are aggregated as vinyl alcohol and ethylene non-ethylene. A copolymer with a saturated alkali metal carboxylic acid neutralized product can be obtained.

After the saponification reaction, the copolymer is acid-treated with an inorganic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid; and an organic acid such as formic acid, acetic acid, oxalic acid, and citric acid, and then lithium hydroxide. , Sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, franchium hydroxide and other different alkali metals (ie different alkali metals), vinyl alcohols and ethylenically unsaturated carboxylic acid alkalis. A copolymer of a metal neutralized product can also be obtained.

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

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the obtained vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal are used. The volume average particle size of the copolymer is preferably 1 to 200 μm, more preferably 10 to 100 μm. When it is 1 μm or more, a more preferable binding effect can be obtained, and when it is 200 μm or less, the thickening liquid becomes more uniform and a preferable binding effect can be obtained. For the volume average particle size of the copolymer, a batch cell (SALD-BC manufactured by Shimadzu Corporation) was installed in a laser diffraction type particle size distribution measuring device (SALD-710 manufactured by Shimadzu Corporation), and 2-propanol or 2-propanol was used as the dispersion solvent. It is a value measured using methanol.

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

Mechanical milling is a method of applying external forces such as impact, tension, friction, compression, and shear to the obtained copolymer, and the devices for that purpose include rolling mills, vibration mills, planetary mills, and rocking mills. , Horizontal mills, attritor mills, jet mills, grinders, homogenizers, fluidizers, paint shakers, mixers and the like. For example, a planetary mill puts a copolymer and a ball together in a container and grinds or mixes the copolymer by the mechanical energy generated by simultaneously rotating and revolving. According to this method, it is pulverized to the nano order.

The thickening effect of the copolymer of the vinyl alcohol and the neutralized ethylenically unsaturated carboxylic acid alkali metal according to the present invention is as follows from the viewpoint of ease of coating of the produced electrode mixture. The viscosity of the 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 even 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 becomes easy. In addition, the dispersibility of the active material and the conductive auxiliary agent in the mixture is also improved. When the viscosity is 10,000 mPa · s or less, the viscosity of the prepared mixture is not too high, and it becomes easier to apply the current collector thinly and uniformly. The viscosity of the 1% by mass aqueous solution is determined by the rotary viscometer (model DV-I +) manufactured by BROOKFIELD, the spindle No. It is a value measured at 5, 50 rpm (liquid temperature 25 ° C.).

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, vinyl alcohol and ethylenically unsaturated carboxylic acid alkali metal neutralization in the binder of the present invention. The proportion of the copolymer with the product is preferably 5% by mass or more, more preferably 20% by mass or more and 95% by mass or less, and further preferably 40% by mass or more and 95% by mass or less.

[Polyvinyl alcohol]
In the binder for a non-aqueous electrolyte secondary battery electrode of the present invention, the polyvinyl alcohol preferably has a saponification degree of 75% or more, more preferably 90% or more, from the viewpoint of solubility in water. Further, as the polyvinyl alcohol preferably used, the degree of polymerization is preferably about 100 to 3000 from the viewpoint of handling.

The number average molecular weight of polyvinyl alcohol is preferably 1,000 to 5,000,000 from the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery. From the viewpoint of having 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 measuring device provided with a GFC column, similarly to the number average molecular weight of the precursor.

Polyvinyl alcohol can be produced by a known method, for example, by polymerizing a vinyl ester in the presence of a catalyst and saponifying it in the presence of a catalyst such as an acid or an alkali. As the polyvinyl alcohol, for example, commercially available products such as the product name "Gosenol" series (manufactured by Nippon Synthetic Chemistry Co., Ltd.) and the product name "Kuraray Poval" series (manufactured by Kuraray Co., Ltd.) can also be used.

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the content of polyvinyl alcohol in the binder of the present invention is based on the total mass of the binder. It is preferably 1% by mass or more, more preferably 1% by mass or more and 60% by mass or less, and further preferably 1% by mass or more and 40% by mass or less.

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, in the binder of the present invention, the mass ratio of the copolymer and polyvinyl alcohol ( The copolymer / polyvinyl alcohol) is preferably 95/5 to 70/30, more preferably 95/5 to 65/35, and even 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 characteristic due to insufficient binding force tends to be suppressed.

[Other ingredients]
In addition to the copolymer of vinyl alcohol and ethylenically unsaturated carboxylic acid alkali metal neutralized product and polyvinyl alcohol, other components may be added to the binder for the electrode of the non-aqueous electrolyte secondary battery of the present invention. .. Other components include those blended in known non-aqueous electrolyte secondary battery electrode binders. Specific examples of other components include carboxymethyl cellulose (CMC), acrylic resin, sodium polyacrylate, sodium alginate, polyimide (PI), polyamide, polyamide-imide, polyacrylic, styrene butadiene rubber (SBR), and ethylene vinyl acetate. Polymer (EVA) can be mentioned. Of these, acrylic resin, sodium polyacrylate, sodium alginate, polyamide, polyamide-imide, and polyimide are preferably used, and acrylic resin is particularly preferably used. As the other component, only one kind may be used, or two or more kinds may be mixed and used.

The binder for the non-aqueous electrolyte secondary battery electrode of the present invention may not contain polyalkylene oxide. That is, in one embodiment of the binder for a non-aqueous electrolyte secondary battery electrode of the present invention, polyalkylene oxide is not contained (the content of 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.

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the proportion of other components in the binder of the present invention is preferably less than 80% by mass. , More preferably 50% by mass or less, still more preferably 20% by mass or less.

From the viewpoint that the binder of the present invention exerts more sufficient binding force and more preferably lowers the resistance of the non-aqueous electrolyte secondary battery, the binder of the present invention is neutralized with vinyl alcohol and ethylenically unsaturated carboxylic acid alkali metal. The total content of the copolymer and polyvinyl alcohol with the product is preferably 20 to 100% by mass with respect to the total mass of the binder.

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

<Electrode mixture for non-aqueous electrolyte secondary batteries>
The electrode mixture for a non-aqueous electrolyte secondary battery of the present invention contains an essential component of a binder for a non-aqueous electrolyte secondary battery electrode of the present invention, an electrode active material (positive electrode active material and a negative electrode active material), and a conductive auxiliary agent. It is an electrode mixture used for manufacturing an electrode for a non-aqueous electrolyte secondary battery.

From the viewpoint of exhibiting more sufficient binding force and more preferably lowering the resistance of the non-aqueous electrolyte secondary battery, the content of the binder of the present invention is 100 mass by mass of the total amount of the electrode active material, the conductive auxiliary agent, and the binder. It is preferably 0.5 to 40 parts by mass, more preferably 1 to 25 parts by mass, and further preferably 1.5 to 10 parts by mass with respect to the 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 further preferably 1.5 to 10% by mass. %. By setting the content to 0.5% by mass or more, deterioration of cycle life characteristics due to insufficient binding force and aggregation due to insufficient viscosity of the slurry tend to be suppressed. On the other hand, when the content is 40% by mass or less, a high capacity tends to be obtained when the battery is charged and discharged.

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 includes a conductive auxiliary agent, a binder of the present invention, and a dispersion auxiliary agent (if necessary). ) And water are added to form a paste-like slurry, which can be produced. The timing of adding water is not particularly limited, and the binder of the present invention may be added by dissolving it in water in advance, or the electrode active material, the conductive auxiliary agent, the dispersion auxiliary agent (if necessary), and the present invention. Water may be added thereto after mixing the binder in a solid state.

The amount of water used is preferably 40 to 2000 parts by mass, more preferably 50 to 1000 parts by mass, based on 100 parts by mass of the total of the electrode active material, the conductive auxiliary agent, and the binder of the present invention. .. By setting the amount of water used within the above range, the handleability of the electrode mixture (slurry) of the present invention tends to be further improved.

[Positive electrode active material]
As the positive electrode active material, the positive electrode active material used in the present 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 ironate 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 ), Lithium tantalate 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 composite oxide, nickel oxide (LiNi _0.5 Mn _1.5 O ₄ ), manganese oxide (MnO ₂ ), vanadium oxide, sulfur oxide, silicate oxide and the like are preferably used. These can be used individually by 1 type or in combination of 2 or more types.

[Negative electrode 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 carbon material, a material capable of occluding and releasing a large amount of lithium ions such as silicon (Si), tin (Sn), and lithium titanate can be used. As long as it is such a material, it is possible to exert the effect of the present embodiment by any of simple substances, alloys, compounds, solid solutions, and composite active materials including silicon-containing materials and tin-containing materials. As the carbon material, crystalline carbon, amorphous carbon, or the like can be used. Examples of crystalline carbons include amorphous, plate-like, flaky, spherical or fibrous graphites such as natural or artificial graphite. Examples of amorphous carbon include soft carbon (graphite easily carbonized) or hard carbon (graphite refined carbonized), mesophase pitch carbide, calcined coke and the like. Silicon-containing materials include Si, SiOx (0.05 <x <1.95), or any of these, B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Nb. , Ta, V, W, Zn, C, N, Sn, an alloy or compound in which a part of Si is substituted with at least one element selected from the group, a solid solution, or the like can be used. These can be called 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 and the like can be applied.
These materials may be used individually by 1 type, or may be used in combination of 2 or more type. Among these, graphite is preferable as the negative electrode active material. By using the binder of the present invention, even when graphite is used as the negative electrode active material, the binder exerts a sufficient binding force, and the non-aqueous electrolyte secondary battery can be suitably lowered in resistance.

Silicon or a silicon compound may be used as the first negative electrode active material, the carbon material as the second negative electrode active material, and the composite obtained by mixing the first and second negative electrode active materials 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 in terms of mass ratio. The carbon material may be any carbon material used in the present technical field, and typical examples thereof include the above-mentioned crystalline carbon and amorphous carbon.

Regarding the method for producing the negative electrode active material, any method may be used as long as the method is such that when the active material composite in which the first negative electrode active material and the second negative electrode active material are mixed is produced, both are uniformly dispersed. As a specific method for producing the negative electrode active material, a method of mixing the first negative electrode active material and the second negative electrode active material with 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 a heat treatment method can be mentioned. The second negative electrode active material precursor may be any carbon precursor that can become a carbon material by heat treatment, for example, glucose, citric acid, pitch, tar, binder material (for example, polyvinylidene fluoride, carboxymethyl cellulose, acrylic). Resin, sodium polyacrylate, sodium alginate, polyimide, polytetrafluoroethylene, polyamide, polyamideimide, polyacrylic, styrene butadiene rubber, polyvinyl alcohol, ethylene vinyl acetate copolymer, etc.) and the like. Commercially available products of these negative electrode active materials are easily available.

The above heat treatment method is a non-oxidizing atmosphere (reducing atmosphere, inert atmosphere, reduced pressure atmosphere, or other atmosphere that is difficult to oxidize) and is heat-treated at 600 to 4000 ° C. to carbonize the carbon precursor to make it conductive. How to get it.

[Conductive aid]
As the conductive auxiliary agent, the conductive auxiliary agent used in the present technical field can be used, and carbon powder is preferable. Examples of carbon powder include acetylene black (AB), ketjen black (KB), graphite, carbon fiber, carbon tube, graphene, amorphous carbon, hard carbon, soft carbon, glassy carbon, carbon nanofiber, and carbon nanotube. (CNT) and the like.

The amount of the conductive auxiliary agent used is preferably 0.1 to 30% by mass, more preferably 0.5 to 10% by mass, and 2 to 2% by mass with respect to 100 parts by mass of the total of the electrode active material, the conductive auxiliary agent and the binder. 5% by mass is more preferable. If the amount of the conductive auxiliary agent used is less than 0.1% by mass, the conductivity of the electrode may not be sufficiently improved. When the amount of the conductive auxiliary agent used exceeds 30% by mass, the proportion of the electrode active material is relatively reduced, so that it is difficult to obtain a high capacity during charging and discharging of the battery, and the surface area is small compared to the electrode active material. It may become large and the amount of binder used may increase.

[Dispersion aid]
The electrode mixture of the present invention may further contain a dispersion aid. The inclusion of the dispersion aid enhances the dispersibility of the electrode active material and the conductive auxiliary agent in the electrode mixture. As the dispersion aid, an organic acid having a molecular weight of 100,000 or less, which is soluble in an aqueous solution having a pH of 7 to 13, is preferable. Among these organic acids, it is preferable to contain at least one of a carboxyl group and a hydroxy group, an amino group or an imino group. Specific examples are compounds having a carboxyl group and a hydroxy group such as lactic acid, tartrate acid, citric acid, malic acid, glycolic acid, tartronic acid, glucuronic acid, and fumic acid; glycine, alanine, phenylalanine, 4-aminobutyric acid, leucine. , Isoleucine, lysine, and other compounds having a carboxyl group and an amino group; compounds having a plurality of carboxyl groups and an amino group such as glutamic acid and aspartic acid; proline, 3-hydroxyproline, 4-hydroxyproline, pipecholine. Compounds having a carboxyl group such as an acid and an imino group; compounds having a carboxyl group such as glutamine, aspartic acid, cysteine, histidine, and tryptophan and a functional group other than a hydroxy group and an amino group can be mentioned. Among these, glutamic acid, humic acid, glycine, aspartic acid, and glutamic acid are preferable from the viewpoint of easy availability.

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

<Electrodes for non-aqueous electrolyte secondary batteries>
The electrode for a non-aqueous electrolyte secondary battery of the present invention uses the electrode mixture of the present invention (that is, the electrode for a non-aqueous electrolyte secondary battery of the present invention), and the method used in the present technology is applied. Can be produced. For example, it can be produced by equipping the current collector with an electrode mixture. More specifically, it can be produced, for example, by applying (and drying if necessary) the electrode mixture on the current collector.

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

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

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

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

Among the non-aqueous electrolyte secondary batteries of the present invention, the lithium ion secondary battery contains lithium ions, and therefore, a lithium salt is preferably used as the electrolyte. Examples of this lithium salt include lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, and lithium imidelithium trifluoromethanesulfonate. One type of electrolyte may be used alone, or two or more types may be used in combination.

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

<Electrical equipment>
The electric device of the present invention is an electric device including 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 that uses at least the non-aqueous electrolyte secondary battery of the present invention as a power source.

Examples of the electric device of the present invention include an air conditioner, a washing machine, a TV, a refrigerator, a personal computer, a tablet, a smartphone, a personal computer keyboard, a monitor, a printer, a mouse, a hard disk, a personal computer peripheral device, an iron, a clothes dryer, a transceiver, a blower, and the like. Music recorder, music player, oven, range, hot air heater, car navigation system, flashlight, humidifier, portable karaoke machine, dry battery, air purifier, game machine, blood pressure monitor, coffee mill, coffee maker, iron, copy machine, disc Changer, radio, shaver, juicer, shredder, water purifier, lighting equipment, dish dryer, rice cooker, trouser press, vacuum cleaner, weight scale, electric carpet, rice cooker, electric pot, electronic dictionary, electronic notebook, electromagnetic cooker , Calculator, electric cart, electric wheelchair, electric tool, electric toothbrush, anka, clock, interphone, air circulator, bug zapper, hot plate, toaster, water heater, crusher, dryer, video camera, video deck, Facsimile, futon dryer, mixer, sewing machine, mochitsuki machine, water cooler, electronic musical instrument, motorcycle, toys, lawn mower, bicycle, car, hybrid car, plug-in hybrid car, railroad, ship, airplane, emergency storage battery, etc. Can be mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Preparation of copolymer A>
Copolymer A was prepared by the following steps 1 to 3.

(Step 1: Synthesis of precursor (precursor) copolymerized with vinyl ester and ethylenically unsaturated carboxylic acid ester)
768 g of water and 12 g of anhydrous sodium sulfate were charged into a reaction vessel having a capacity of 2 L equipped with a stirrer, a thermometer, an N ₂ gas introduction pipe, a reflux cooler and a dropping funnel, and N ₂ gas was blown into the system to deoxidize the inside of the system. Subsequently, 1 g of partially saponified polyvinyl alcohol (88% saponification) and 1 g of lauryl peroxide were charged, the internal temperature was raised to 60 ° C., and then 104 g (1.209 mol) of methyl acrylate and 155 g (1) of vinyl acetate were added. .802 mol) was added dropwise over 4 hours using a dropping funnel. Then, the internal temperature was maintained at 65 ° C. for 2 hours. Then, the solid content was filtered off to obtain 288 g (10.4% by mass) of the precursor. The obtained precursor was dissolved in DMF, filtered through a filter, and the molecular weight of the precursor in the filtrate was measured using a molecular weight measuring device (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 neutralized ethylenically unsaturated carboxylic acid alkali metal)
450 g of methanol, 420 g of water, 132 g of sodium hydroxide (3.3 mol) and 288 g of the precursor obtained in step 1 (containing 10.4% by mass) were charged in the same reaction vessel as in step 1 and 30 ° C. under stirring. The saponification reaction was carried out for 3 hours. After completion of the saponification reaction, the obtained copolymer was washed with methanol, filtered, and dried at 70 ° C. for 6 hours to obtain a vinyl ester / ethylenically unsaturated carboxylic acid ester copolymer (vinyl alcohol and ethylenically unsaturated carboxylic). A copolymer with an acid-alkali metal neutralized product, sodium alkali metal, saponification degree 98.8%) 193 g was obtained. The volume average particle size of the obtained copolymer was 180 μm.

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

<Preparation of binder, electrode mixture, and electrode>
(Example 1)
2.7 parts by mass of the copolymer A obtained above and 0.3 parts by mass of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Kuraray Poval 105, number average molecular weight 22,000) 0.3 parts by mass are dissolved in 50 parts by mass of water to make a binder. An aqueous solution of (binder composition) was obtained. Next, 96.5 parts by mass of artificial graphite (manufactured by Hitachi Chemical Co., Ltd., MAG-D) as the electrode active material, and acetylene black (AB) (manufactured by Denki Kagaku Kogyo Co., Ltd., registered) as the conductive auxiliary agent. Trademark)) 0.5 parts by mass was added to the above aqueous binder solution and kneaded. Further, 70 parts by mass of water for adjusting the viscosity was added and kneaded to prepare a slurry negative electrode mixture. The obtained negative electrode mixture is applied onto an electrolytic copper foil having a thickness of 10 μm, dried, and then the electrolytic copper foil and the coating film are closely bonded by a roll press machine (manufactured by Ohno Roll Co., Ltd.). Was heat-treated (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 capacitance density of the negative electrode was 3.0 mAh / cm ² .

(Example 2)
In Example 1, 2.4 parts by mass of copolymer A was used, and 0.6 parts by mass of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Kuraray Poval 105, number average molecular weight 22,000) was used. A negative electrode was prepared in the same manner as in Example 1. The thickness of the active material layer in the obtained negative electrode was 101 μm, and the capacitance density of the negative electrode was 3.0 mAh / cm ² .

(Comparative Example 1)
A negative electrode was prepared in the same manner as in Example 1 except that 3.0 parts by mass of the copolymer A was used and polyvinyl alcohol was not used. The thickness of the active material layer in the obtained negative electrode was 99 μm, and the capacitance density of the negative electrode was 3.0 mAh / cm ² .

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

(Peeling test)
The peel strength test of the coating film (negative electrode active material layer) on the current collector in the negative electrodes obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was performed. After cutting out the negative electrode to a width of 80 mm x 15 mm and attaching the adhesive tape to the surface (negative electrode active material layer side), attach it to a stainless steel plate with double-sided tape to fix the negative electrode (current collector side) and use it for evaluation. It was used as a sample. This evaluation sample was subjected to a 180-degree peel test of the negative electrode on a stainless steel plate (180 degree adhesive tape on the negative electrode fixed to the stainless steel plate) using a tensile tester (small desktop tester EZ-Test manufactured by Shimadzu Corporation). A degree peeling test) was carried out, and the peeling strength between the active material layer and the current collector at the negative electrode was measured. Table 1 shows the evaluation results of the peeling test (peeling strength).

(Electrode strength)
The strength of the electrode (“electrode strength”” depends on the presence or absence of peeling, falling off, 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. ) Was evaluated. Table 2 shows the evaluation results of the electrode strength.

○ (excellent in strength): Of the 10 electrodes that were randomly punched out, 2 or less were confirmed to have peeling, falling off, or chipping of the active material layer by visual judgment.
Δ (Slightly excellent in strength): Of the 10 electrodes that were randomly punched out, 3 to 5 were confirmed to have peeling, falling off, or chipping of the active material layer by visual judgment.
× (Inferior in strength): Of the 10 electrodes that were randomly punched out, 6 or more were confirmed to have peeling, falling off, or chipping of the active material layer by visual judgment.

(Battery assembly)
A coin cell (CR2032) provided with the negative electrodes obtained in Examples 1 and 2 and Comparative Examples 1 and 2 and the following counter electrode, separator, and electrolytic solution was prepared, and subjected to 3 cycles at 0.1 C in an environment of 30 ° C. A sample (coin cell) was prepared by performing an aging treatment.

・ Counter electrode: Metallic lithium ・ Separator: Glass filter (manufactured by Advantech Co., Ltd., GA-100)
-Electrolytic solution: LiPF ₆ is dissolved in a solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of 1: 1 at a concentration of 1 mol / L, and vinylene carbonate (VC), which is an additive for the electrolytic solution, is dissolved. ) To 1% by volume

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

Claims (10)

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