JP2003157851A - Thermosetting polyvinyl alcohol-based binder resin composition, mixture slurry, electrode, non-aqueous electrolyte secondary battery and thermosetting polyvinyl alcohol-based binder resin for electrode material - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To have excellent electrolyte resistance at a high temperature (50 ° C.) close to the upper limit temperature of use of a lithium secondary battery, and to prevent the mixture layer from cracking, peeling or falling off in the battery manufacturing process. A polyvinyl alcohol-based thermosetting binder resin composition having good flexibility and flexibility; a mixture slurry containing the thermosetting binder resin composition and a positive electrode active material or a negative electrode active material; An electrode obtained by coating and drying a body; and providing a non-aqueous electrolyte secondary battery having a high temperature and a long life which can significantly reduce a decrease in energy capacity in a charge and discharge cycle at 50 ° C. using the electrode. A thermosetting binder resin composition comprising (A) a thermosetting polyvinyl alcohol-based resin, (B) an acrylic resin-based plasticizer, and (C) a solvent; a thermosetting unit represented by the general formula (III): A thermosetting binder resin composition containing a thermosetting polyvinyl alcohol-based binder resin having a solvent and a solvent; a mixture slurry containing the binder resin composition;
Electrodes and non-aqueous electrolyte secondary batteries using this. Embedded image (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.)

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyvinyl alcohol-based thermosetting binder resin composition, a mixture slurry,
The present invention relates to a thermosetting polyvinyl alcohol-based binder resin for electrodes, non-aqueous electrolyte secondary batteries, and electrode materials for non-aqueous electrolyte secondary batteries.

[0002]

2. Description of the Related Art As electronic devices are becoming smaller and more portable, a secondary battery having a high energy density and a long life is desired as a power source. In recent years, a non-aqueous electrolyte type lithium ion secondary battery (hereinafter, referred to as a lithium secondary battery) capable of significantly improving energy density has been developed and rapidly spread. This lithium secondary battery uses a lithium-containing metal composite oxide as an active material of a positive electrode, and has a multilayer structure capable of intercalating lithium ions (forming a lithium intercalation compound) and releasing lithium ions as an active material of a negative electrode. It mainly uses the carbon materials it has. For the positive and negative electrode plates, these active materials and a binder resin composition (binder resin + N-methyl-2-pyrrolidone or a solvent such as water) are kneaded to prepare a mixture slurry, which is then collected. After coating both sides on the metal foil that is the body, after removing the solvent by drying to form the mixture layer,
It is made by compression molding with a roll press. As this binder resin, polyvinylidene fluoride (hereinafter referred to as PVDF) is frequently used for both the positive electrode and the negative electrode.

However, when PVDF is used as the binder resin, the adhesiveness at the interface between the current collector and the mixture layer is inferior, so (1) cutting the positive electrode plate and the negative electrode plate, or using the separator as a separator. Part or all of the mixture layer is peeled off from the current collector in the step of spirally winding through,
(2) Since the carbon material of the negative electrode active material expands and contracts during charge and discharge of the lithium secondary battery, there is a problem that part or all of the mixture layer is peeled off from the current collector. This was one of the causes of the decrease in energy capacity in the charge / discharge cycle of the secondary battery.

As a solution to this problem, for example, Japanese Patent Laid-Open No. 172452/1994 discloses a fluorine-containing product obtained by copolymerizing vinylidene fluoride as a main component with a small amount of unsaturated dibasic acid monoester. There is a disclosure of using a vinylidene chloride-based copolymer. However, when such a vinylidene fluoride-based copolymer is used as a binder resin, the adhesiveness at the interface between the current collector and the mixture layer is significantly improved, but (1) after winding due to a decrease in crystallinity. The resistance to the injected electrolytic solution (hereinafter referred to as the electrolytic solution resistance) decreases and the swelling tends to occur, and the contact between the interface between the current collector and the mixture layer and the contact between the active materials in the mixture layer It becomes loose, and this leads to the collapse of the conductive network of the whole electrode plate, which lowers the energy capacity of the battery. (2) Decomposition accompanied by desorption and generation of highly corrosive hydrogen fluoride under high voltage However, there is an adverse effect that the battery tends to occur, the internal pressure rises, and the battery does not function, and the essential problem has not been solved.

As a binder resin which substitutes for a fluorine-containing resin such as PVDF, it is proposed to use a diene-based synthetic rubber such as styrene-butadiene rubber (hereinafter referred to as SBR) in JP-A-5-74461. Has been done. However, although many diene-based synthetic rubbers such as SBR have good electrolytic solution resistance by themselves, the stability of the active material in the mixture slurry is remarkably poor and the active material easily precipitates. Therefore, it is necessary to add a thickener such as cellulose or a surfactant, and these additives are dissolved in the electrolytic solution, so that there is a problem that the energy capacity of the lithium secondary battery is lowered. On the other hand, a material system having properties different from those of the fluorine-containing or rubber binder resin has been proposed. For example, JP-A-9-115506, JP-A-11-67215, and JP-A-11-67216.
Japanese Patent Application Laid-Open No. 11-250915 and Japanese Patent Application Laid-Open No. 11-250915 disclose a hydrogen bond type binder resin mainly composed of polyvinyl alcohol.

However, since all of these polyvinyl alcohol-based binder resins are thermoplastic, the electrolyte resistance at a high temperature (50 ° C.) near the upper limit temperature of use of the lithium secondary battery is insufficient, and the lithium secondary battery Since the battery has a short life at high temperature and is a rigid polymer having crystallinity, it is insufficient in flexibility and flexibility when used alone, and cracks in the mixture layer during roll press molding or winding process, There is a problem that a normal lithium secondary battery is difficult to manufacture due to peeling and dropping.

[0007]

The object of the present invention is to provide excellent resistance to an electrolytic solution at a high temperature (50 ° C.) close to the maximum usable temperature of a lithium secondary battery, and to crack the mixture layer in the battery manufacturing process. Another object of the present invention is to provide a polyvinyl alcohol-based thermosetting binder resin composition which is free from peeling and falling and has good flexibility and flexibility. Another object of the present invention is to provide a mixture slurry containing at least the above-mentioned polyvinyl alcohol-based thermosetting binder resin composition and a positive electrode active material or a negative electrode active material. Another object of the present invention is to provide an electrode obtained by applying the mixture slurry to a current collector and drying it. Further, another object of the present invention is to
It is an object of the present invention to provide a non-aqueous electrolyte secondary battery having a high temperature and a long life, which can significantly reduce a decrease in energy capacity in a charge / discharge cycle at 50 ° C. using the above electrode. Still another object of the present invention is to provide a thermosetting polyvinyl alcohol-based binder resin for an electrode material of a non-aqueous electrolyte secondary battery.

[0008]

The present invention provides the following thermosetting polyvinyl alcohol-based binder resin composition, mixture slurry, electrode, non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery. A thermosetting polyvinyl alcohol-based binder resin for an electrode material is provided. 1. A thermosetting binder resin composition comprising (A) a thermosetting polyvinyl alcohol-based binder resin, (B) an acrylic resin-based plasticizer, and (C) a solvent. 2. The thermosetting binder resin composition according to the above 1, wherein the component (A) has a thermosetting unit represented by the general formula (I).

[0009]

[Chemical 5] (In the formula, R represents a divalent organic group.) 3. The component (B) is a polymer of a monomer represented by the general formula (II) or a derivative of the polymer, and the above-mentioned 1
The thermosetting binder resin composition described.

[0010]

[Chemical 6] (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents hydrogen, a glycidyl group, or an alkyl group having 6 to 18 carbon atoms.) 4. The component (C) is a nitrogen-containing organic solvent or a mixed solvent containing the same, any one of the above 1 to 3.
Item 2. A thermosetting binder resin composition according to item. 5. A thermosetting binder resin composition comprising a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III) and a solvent.

[0011]

[Chemical 7] (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 6. The thermosetting binder resin composition according to the above 5, wherein the alkenyl group in the thermosetting unit is a dodecenyl group. 7. Solubility parameter is 24.5-26.5 (MJ / m ³ ) ^1/2
A thermosetting binder resin composition comprising a thermosetting binder resin and a solvent.

8. A mixture slurry containing the thermosetting binder resin composition according to any one of 1 to 7 above and a positive electrode active material or a negative electrode active material. 9. 9. The mixture slurry according to the above item 8, wherein the positive electrode active material is a lithium-containing metal composite oxide capable of reversibly inserting and releasing lithium ions by charging and discharging. 10. 9. The mixture slurry according to the above 8, wherein the negative electrode active material is a carbon material capable of reversibly inserting and releasing lithium ions by charging and discharging. 11. An electrode obtained by applying the mixture slurry according to any one of the above 8 to 10 to a current collector and drying. 12. A non-aqueous electrolyte secondary battery comprising the electrode described in 11 above. 13. In a non-aqueous electrolyte system secondary battery containing an electrode and an electrolytic solution containing a chain organic solvent, the electrode collects a thermosetting binder resin composition and a mixture slurry containing a positive electrode active material or a negative electrode active material. It is obtained by coating on an electric body and drying,
Solubility parameter (SP value) of the thermosetting binder resin
And a difference in SP value between the chain organic solvents is 3 (MJ / m ³ ) ^1/2 or more, a non-aqueous electrolyte secondary battery. 14. 14. The non-aqueous electrolyte system according to 13 above, wherein the degree of swelling of the thermosetting binder resin with respect to the electrolytic solution at 50 ° C. is higher than that at 25 ° C., and the degree of swelling at 50 ° C. is less than 10%. Secondary battery. 15. 14. The non-aqueous electrolyte secondary battery according to 13 above, wherein the thermosetting binder resin has a winding property. 16. 14. The non-aqueous electrolyte secondary battery according to the above 13, wherein the thermosetting binder resin is a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III).

[0013]

[Chemical 8] (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 17. The non-aqueous electrolyte secondary battery according to the above 16, wherein the alkenyl group in the thermosetting unit is a dodecenyl group. 18. 14. The thermosetting binder resin composition contains (A) a thermosetting polyvinyl alcohol-based binder resin, (B) an acrylic resin-based plasticizer, and (C) a solvent, as described in 13 above. Secondary battery. 19. For the electrode material of non-aqueous electrolyte secondary batteries, the general formula (I
A thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by II).

[0014]

[Chemical 9] (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 20. 20. The thermosetting polyvinyl alcohol-based binder resin as described in 19, wherein the alkenyl group in the thermosetting unit is a dodecenyl group.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the thermosetting binder resin composition of the present invention, the thermosetting polyvinyl alcohol-based binder resin (A) is obtained by introducing a thermosetting unit into the polyvinyl alcohol-based resin. For example, a polyvinyl alcohol-based resin having a carboxyl group, an epoxy group, or the like introduced as a thermosetting unit can be used. Of these, a polyvinyl alcohol-based resin having a carboxyl group introduced therein is preferable in terms of compatibility between thermosetting property and storage stability, and among them, in terms of easiness of introduction of a carboxyl group, the general formula (I)

[0016]

[Chemical 10] A polyvinyl alcohol-based resin having a thermosetting unit represented by the formula (wherein R represents a divalent organic group) is more preferable. These (A) components are preferably used alone or in combination of two or more kinds.

The introduction of the thermosetting unit represented by the above general formula (I) into the polyvinyl alcohol resin is usually carried out.
It is carried out by reacting a polyvinyl alcohol resin with a cyclic acid anhydride. At this time, when alkenylsuccinic anhydride is used as the cyclic acid anhydride, a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III) can be obtained. Hereinafter, unless otherwise specified, the “cyclic acid anhydride” includes “alkenylsuccinic anhydride”.

The polyvinyl alcohol-based resin is not particularly limited, but in view of resistance to electrolytic solution and the like, the saponification degree (JI
SK 6726: based on the polyvinyl alcohol test method), preferably 85 mol% or more, and 90 mol%
The above is more preferable, 95 mol% or more is particularly preferable,
98 mol% or more is extremely preferable. The average degree of polymerization (JIS K 6726: based on the polyvinyl alcohol test method) is preferably 500 to 5,000,
1,000 to 3,000 is more preferable, and 1,500 to 2,
500 is particularly preferable. Average degree of polymerization is 500
When the amount is less than the above, the active material in the mixture slurry is liable to settle and the storage stability is poor, and when the average degree of polymerization exceeds 5,000, the solubility in the solvent is lowered and the handling tends to be difficult. .

The polyvinyl alcohol-based resin may be various modified products (for example, one in which a long-chain alkyl group or the like is partially introduced into a side chain). These polyvinyl alcohol resins are used alone or in combination of two or more. The cyclic acid anhydride is not particularly limited, and examples thereof include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride. , Nadic acid anhydride, methyl nadic acid anhydride, methyl 2-substituted butenyl tetrahydrophthalic acid anhydride, itaconic acid anhydride, succinic acid anhydride, citraconic acid anhydride, dodecenyl succinic acid anhydride, maleic acid anhydride, methyl Cyclopentadiene maleic anhydride adduct, alkylated endoalkylene tetrahydrophthalic anhydride, phthalic anhydride, chlorendic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, tricarballylic anhydride, Maleinic anhydride linoleic acid adduct, male Sorbic acid adducts of phosphate anhydride include trimellitic anhydride. Among these, succinic anhydride having less steric hindrance is preferable in terms of reactivity with the alcoholic hydroxyl group in the polyvinyl alcohol-based resin, thermosetting property of the resulting component (A), and the like. These cyclic acid anhydrides may be used alone or in combination of two or more.

The alkenylsuccinic anhydride used for producing the thermosetting polyvinyl alcohol-based binder resin having the thermosetting unit represented by the general formula (III) is not particularly limited, but is flexible and flexible. In terms of flexibility and the like, those having a dodecenyl group (alkenyl group having 12 carbon atoms) are preferable. These alkenyl succinic anhydrides may be used alone or in combination of two or more. Further, a cyclic acid anhydride other than alkenylsuccinic anhydride may be used in combination for the purpose of adjusting thermosetting property, crystallinity and the like.

The reaction ratio of the polyvinyl alcohol resin and the cyclic acid anhydride other than the alkenyl succinic anhydride is such that the acid anhydride group of the cyclic acid anhydride is 0 relative to 1 equivalent of the alcoholic hydroxyl group of the polyvinyl alcohol resin. .01
~ 0.50 equivalents are preferred, 0.03 to 0.3
It is more preferably 0 equivalent, and particularly preferably 0.05 to 0.20 equivalent. When the acid anhydride group of the cyclic acid anhydride is less than 0.01 equivalent, the thermosetting property of the obtained component (A) tends to decrease, and the electrolytic solution resistance tends to decrease.
If it exceeds 0.50 equivalents, the crosslink density after thermosetting becomes too large and becomes brittle, and the mixture layer is cracked, peeled or dropped during the battery manufacturing process, making it difficult to manufacture a normal battery. In addition, the cyclic acid anhydride tends to remain as an unreacted product.

The reaction ratio between the polyvinyl alcohol resin and the alkenyl succinic anhydride (+ other cyclic acid anhydride) is
There is no particular limitation, but 0.001 to 0.50 equivalent of the acid anhydride group of the alkenyl succinic anhydride (+ other cyclic acid anhydride) is equivalent to 1 equivalent of the alcoholic hydroxyl group of the polyvinyl alcohol resin. Preferably 0.005-0.3
0 equivalent is more preferable, and 0.01 to 0.20 equivalent is particularly preferable. When the acid anhydride group of the alkenyl succinic anhydride (+ other cyclic acid anhydride) is less than 0.001 equivalent, flexibility and flexibility tend to be insufficient, and the thermosetting property is high. Tends to decrease and the electrolytic solution resistance tends to decrease.
If it exceeds 50 equivalents, the crosslink density after thermosetting becomes too large and becomes brittle, and the mixture layer tends to be cracked, peeled off, or dropped during the battery manufacturing process, making it difficult to produce a normal battery. Further, the crystallinity tends to decrease, the electrolytic solution resistance tends to decrease, and the alkenyl succinic anhydride (+ other cyclic acid anhydride) tends to remain as an unreacted substance.

The reaction between the polyvinyl alcohol resin and the cyclic acid anhydride is preferably carried out in an organic solvent in a substantially anhydrous state. The organic solvent is not particularly limited and includes, for example, amides such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, N, N-dimethylethyleneurea and N, N-dimethyl. Propylene urea, ureas such as tetramethylurea, γ-butyrolactone, lactones such as γ-caprolactone, carbonates such as propylene carbonate,
Ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, esters such as ethyl carbitol acetate, diglyme, triglyme, and glyme such as tetraglyme. Type, toluene,
Examples thereof include hydrocarbons such as xylene and cyclohexane, sulfones such as sulfolane, and the like. Among these, amides and ureas of nitrogen-containing organic solvents are preferable in terms of high solubility in polyvinyl alcohol resins, high reaction accelerating reaction between polyvinyl alcohol resins and cyclic acid anhydrides, and polyvinyl alcohol resins. N does not have active hydrogen, which tends to hinder the reaction of the cyclic acid anhydride with N.
-Methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylethyleneurea, N, N-dimethylpropyleneurea and tetramethylurea are more preferable, and N-methyl-2-pyrrolidone is particularly preferable. These organic solvents may be used alone or in combination of two or more.

The amount of the organic solvent used is preferably 50 to 10,000 parts by weight, and 200 to 5,500 parts by weight, based on 100 parts by weight of the total amount of the polyvinyl alcohol resin and the cyclic acid anhydride.
000 parts by mass is more preferable, and 300 to 3,000 parts by mass is particularly preferable. If the amount used is less than 50 parts by mass, the solubility will be poor and the reaction system will tend to become non-uniform and the viscosity will increase, and if it exceeds 10,000 parts by mass, the reaction will be difficult to complete.

The reaction temperature between the polyvinyl alcohol resin and the cyclic acid anhydride is preferably 40 to 250 ° C., and 60 to 250 ° C.
200 degreeC is more preferable, and it is especially preferable to set it as 80-150 degreeC. The reaction time is preferably 10 minutes or longer, more preferably 30 minutes to 10 hours, and particularly preferably 1 to 5 hours. If the reaction temperature is less than 40 ° C, the reaction is difficult to proceed and the reaction is difficult to complete. Reaction temperature is 250
If the temperature exceeds ℃, the system may gel due to side reactions,
The reaction becomes difficult to control. Further, if the reaction time is less than 10 minutes, it becomes difficult to complete the reaction.

In the reaction between the polyvinyl alcohol resin and the cyclic acid anhydride, a catalyst can be used if necessary. Examples of the catalyst include triethylamine,
Triethylenediamine, N, N-dimethylaniline,
N, N-diethylaniline, N, N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N, N-dimethylpiperazine, viridine, picoline, 1,8-diazabicyclo [5,4,0] undecene- Tertiary amines such as 7, 2-methylimidazole, 2-
Ethylimidazole, 2-ethyl-4-methylimidazole, 2-methyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4-methyl-l-hydroxy Imidazoles such as methyl imidazole, 2-phenyl-4,5-dihydroxymethyl imidazole, 1-azine-2-methyl imidazole, dibutyltin dilaurate, organotins such as 1,3-diacetoxy tetrabutyl distanoxane, odor Tetraethylammonium bromide, tetrabutylammonium bromide, benzyltriethylammonium chloride, trioctylmethylammonium chloride, cetyltrimethylammonium bromide,
Quaternary onium salts such as tetrabutylammonium iodide, dodecyltrimethylammonium iodide, benzyldimethyltetradecylammonium acetate, tetrafellphosphonium chloride, triphenylmethylphosphonium chloride, tetramethylphosphonium bromide, 3-methyl-1-phenyl- Organophosphorus compounds such as 2-phospholen-1-oxide, alkali metal salts of organic acids such as sodium benzoate and potassium benzoate, inorganic salts such as zinc chloride, iron chloride, lithium chloride and lithium bromide, octacarbonyldicobalt Examples thereof include metal carbonyl compounds such as (cobalt carbonyl) and metal ether compounds such as tetrabutoxy titanium. These catalysts can be used alone or in combination of two or more. The amount of these catalysts used is 0.01 to the solid content of the reaction system.
It is about 10% by mass. The solubility parameter of the thermosetting polyvinyl alcohol-based binder resin of the present invention is preferably 23.5 to 27.5 (MJ / m ³ ) ^1/2 , and more preferably 24.5 to 26.5 (MJ / m ³ ). ³ ) ^1/2 .

The component (B) of the acrylic resin plasticizer in the present invention is not particularly limited as long as it imparts the winding property to the electrode. For example, the general formula (II)

[0028]

[Chemical 11] (Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents hydrogen, a glycidyl group or an alkyl group having 6 to 18 carbon atoms), or a polymer of the monomer or a derivative of the polymer. Preferably, R ₂ in the general formula (II) has 6 carbon atoms.
More preferred are copolymers of an alkyl group monomer of 1 to 18 and hydrogen or a glycidyl group monomer or derivatives of the copolymer, wherein R ₁ in the general formula (II) is hydrogen and R ₂ is carbon. Monomer of alkyl group with 12 atoms (lauryl acrylate)
A derivative of a monomer (acrylic acid) copolymer in which / R ₁ is hydrogen and R ₂ is hydrogen is particularly preferable. When the number of carbon atoms of the alkyl group of R ₂ is less than 6, the electrolytic solution resistance is lowered. On the other hand, if the number of carbon atoms exceeds 18, the polymerizability will decrease. These (B) components are used alone or in combination of two or more.

When the lauryl acrylate / acrylic acid copolymer is used as the precursor of the component (B), its weight average molecular weight is preferably 1,000 to 1,000,000, more preferably 1,000 to 100,000. Preferably 1,
It is particularly preferable that it is 000 to 10,000. If the weight average molecular weight is less than 1,000, the function as a plasticizer cannot be sufficiently exerted, and the weight average molecular weight is 1,000,000.
When it exceeds, the compatibility with the component (A) and the solubility in a solvent are lowered and the handling becomes difficult. The acid value is 10 to 50.
0 KOHmg / g is preferable, 30 to 200 KOHmg
/ G is more preferable, and 50 to 150 KOHmg / g is particularly preferable. When the acid value is less than 10 KOHmg / g, derivatization becomes difficult, and the acid value is 500 KOHmg / g.
If it exceeds g, the function as a plasticizer decreases.

As component (B), lauryl acrylate /
When a derivative of an acrylic acid copolymer is used, examples of the derivative include a reaction between a lauryl acrylate / acrylic acid copolymer and polyoxazoline, polyisocyanate, melamine resin, polycarbodiimide, polyol, polyamine, epoxy resin, etc. Things can be mentioned. Of these, easy derivatization, compatibility with component (A),
From the viewpoint of imparting high plasticity to the thermosetting binder resin composition of the present invention, a reaction product of a lauryl acrylate / acrylic acid copolymer and an epoxy resin is preferable.

Examples of the epoxy resin include bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl. -Functional aromatic glycidyl ether such as epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, dicyclopentadiene-phenol epoxy resin, tetraphenylolethane epoxy resin and other polyfunctional aromatic glycidyl ether, polyethylene Glycol type epoxy resin, polypropylene glycol type epoxy resin, neopentyl glycol type epoxy resin, dibromo neopentyl glycol type epoxy resin Difunctional aliphatic glycidyl ethers such as hexanediol type epoxy resin, bifunctional alicyclic glycidyl ethers such as hydrogenated bisphenol A type epoxy resin, trimethylolpropane type epoxy resin, sorbitol type epoxy resin, glycerin type epoxy resin, etc. Functional aliphatic glycidyl ether, difunctional aromatic glycidyl ester such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, dimer acid diglycidyl ester, hydrogenated dimer acid diglycidyl ester, etc. Bifunctional alicyclic glycidyl ester, N, N-diglycidylaniline, N, N-diglycidyltrifluoromethylaniline, or other bifunctional aromatic glycidylamine, N, N, N ',
N'-tetraglycidyl-4,4-diaminodiphenylmethane, 1,3-bis (N, N-glycidylaminomethyl)
Cyclohexane, polyfunctional aromatic glycidyl amines such as N, N, O-triglycidyl-p-aminophenol, alicyclic diepoxy acetal, alicyclic diepoxy adipate, alicyclic diepoxy carboxylate, vinylcyclohexene dioxide A bifunctional alicyclic epoxy resin such as, a difunctional heterocyclic epoxy resin such as diglycidyl hydantoin, a polyfunctional heterocyclic epoxy resin such as triglycidyl isocyanurate, or a bifunctional or polyfunctional organopolysiloxane type epoxy resin Silicon-containing epoxy resin, difunctional epoxy resin and aliphatic dicarboxylic acid (succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosane diacid, alkylene ether bond-containing dicarbohydrate) Acid, alkylene carbonate bond-containing dicarboxylic acid, butadiene bond-containing dicarboxylic acids,
Obtained by chain extension reaction with hydrogenated butadiene bond-containing dicarboxylic acid, dimethylsiloxane bond-containing dicarboxylic acid, etc.) and / or alicyclic dicarboxylic acid (1,4-cyclohexanedicarboxylic acid, dimer acid, hydrogenated dimer acid, etc.) And epoxy resin.

Of these, a bifunctional type epoxy resin is preferable from the viewpoint of compatibility between plasticity and thermosetting of the polyvinyl alcohol type thermosetting binder resin composition of the present invention. These epoxy resins are used alone or in combination of two or more. The reaction ratio of the lauryl acrylate / acrylic acid copolymer and the epoxy resin is such that the epoxy group of the epoxy resin is 0.01 with respect to 1 equivalent of the carboxyl group of the lauryl acrylate / acrylic acid copolymer.
~ 5 equivalents are preferred, 0.1-4 equivalents are more preferred,
0.3 to 3 equivalents are particularly preferred, and 0.5 to 2 equivalents are highly preferred. When the epoxy group of the epoxy resin is less than 0.01 equivalent, the compatibility with the component (A) and the plasticity of the polyvinyl alcohol-based thermosetting binder resin composition of the present invention become insufficient, and the epoxy group of the epoxy resin becomes If the amount exceeds 5 equivalents, the formation of cross-links due to side reactions becomes excessive and the reaction system tends to gel.

The reaction temperature between the lauryl acrylate / acrylic acid copolymer and the epoxy resin is preferably 40 to 250 ° C, more preferably 60 to 200 ° C, and 80 to 150.
It is particularly preferable to set the temperature to ° C. The reaction time is 10
Minutes or more, more preferably 30 minutes to 10 hours,
Particularly preferably, the time is from 1 to 5 hours. Reaction temperature is 40
When the reaction temperature is lower than 0 ° C, the reaction is difficult to complete, and when the reaction temperature is higher than 250 ° C, the system may gel due to side reaction, which makes it difficult to control the reaction. Further, if the reaction time is less than 10 minutes, it becomes difficult to complete the reaction.

The component (C) in the present invention is not particularly limited, and examples thereof include water, alcohols, and organic solvents usable for the reaction between the polyvinyl alcohol resin and the cyclic acid anhydride described above. It can be given as it is. Among these, nitrogen-containing organic solvents such as amides and ureas are preferable, and N-methyl-2-pyrrolidone or a mixed solvent containing it is more preferable. These (C) components are used alone or in combination of two or more.

The mixing ratio of the component (A) and the component (B) in the thermosetting binder resin composition of the present invention is such that the component (A) is 10
The component (B) is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and particularly preferably 5 to 20 parts by mass with respect to 0 parts by mass. (B)
If the component is less than 1 part by mass, plasticization is insufficient,
When the amount of the component (B) exceeds 50 parts by mass, the thermosetting property decreases and the electrolytic solution resistance decreases. The mixing ratio of the component (C) is an arbitrary amount that is not overdiluted, because the component (C) is added as necessary in the subsequent mixture slurry preparation step. In addition, the thermosetting binder resin composition containing the thermosetting polyvinyl alcohol-based binder resin having the thermosetting unit represented by the general formula (III) can be wound on the electrode without using the component (B). Can be given.

In the thermosetting binder resin composition of the present invention, if necessary, materials other than the components (A), (B) and (C), for example, active material in the mixture slurry are prevented from settling. For this purpose, various additives such as a thixotropy-imparting agent, a thickener, a dispersant, a defoaming agent for improving the coating property of the electrode, and a leveling agent can be added.

The first mixture slurry of the present invention comprises at least a thermosetting binder resin composition containing the above-mentioned components (A), (B) and (C) and a positive electrode active material or a negative electrode active material. . The second mixture slurry of the present invention is a thermosetting binder resin composition containing at least a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III) and a solvent, and a positive electrode. It has an active material or a negative electrode active material. The solvent is not particularly limited, and examples thereof include water, alcohols, and organic solvents that can be used for the reaction with the above-mentioned alkenylsuccinic anhydride (+ other cyclic acid anhydride) as they are. To be Among these, nitrogen-containing organic solvents such as amides and ureas are preferable, and N-methyl-2-pyrrolidone or a mixed solvent containing it is more preferable. These solvents may be used alone or in combination of two or more.

The positive electrode and negative electrode active materials are not particularly limited as long as they can reversibly insert and release lithium ions by charging and discharging a lithium secondary battery. As the positive electrode active material, for example, a lithium-containing metal composite oxide containing at least one metal selected from lithium and iron, cobalt, nickel, and manganese is preferable. On the other hand, as the negative electrode active material, for example, amorphous carbon,
Carbon materials such as graphite, carbon fiber, coke, and activated carbon are preferable, and a composite of such a carbon material and a metal such as silicon, tin, or silver, or an oxide thereof can also be used. These active materials may be used alone or in combination of two or more. It should be noted that a conductive auxiliary agent such as carbon black or acetylene black may be added to the mixture slurry of the positive electrode singly or in combination of two or more kinds.

The volume ratio [binder resin / active material] of the thermosetting polyvinyl alcohol-based binder resin and the positive electrode active material or the negative electrode active material in the mixture slurry is [1/99] to
[20/80] is preferable. If this volume ratio [binder resin / active material] is less than [1/99], the mixture layer may crack, peel, or fall off during the battery manufacturing process, making it difficult to manufacture a normal electrode and battery. 80], the energy capacity of the lithium secondary battery tends to decrease.
In addition, the blending ratio of the solvent is an arbitrary amount that is not excessively diluted.

The electrode of the present invention is obtained by applying the above mixture slurry to a current collector and drying it, and the non-aqueous electrolyte secondary battery of the present invention is produced using the electrode. The method for producing the electrode and the non-aqueous electrolyte secondary battery of the present invention is not particularly limited, and any known method can be used.

The non-aqueous electrolytic solution of the non-aqueous electrolytic solution type secondary battery of the present invention is not particularly limited as long as it can function as a secondary battery. For example, propylene carbonate, ethylene carbonate and butylene. Carbonate,
Carbonates such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, lactones such as γ-butyrolactone, trimethoxymethane, 1,2-
Ethers such as dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, sulfoxides such as dimethyl sulfoxide, 1,3-dioxolane, 4-methyl-1,3
-Oxolanes such as dioxolane, nitrogen-containing compounds such as acetonitrile, nitromethane, N-methyl-2-pyrrolidone, esters such as methyl formate, methyl acetate, butyl acetate, methyl propionate, ethyl propionate, and phosphoric acid triester; Glymes such as diglyme, triglyme and tetraglyme, ketones such as acetone, diethyl ketone, methyl ethyl ketone and methyl isobutyl ketone, sulfolanes such as sulfolane, oxazolidinones such as 3-methyl-2-oxazolidinone and 1,3-propanesal Tones, 4-butane sultone, naphtha sultone, and other organic solvents such as LiClO ₄ , LiB
F ₄ , LiI, LiCl ₄ , LiPF ₆ , LiCF ₃ S
_{O 3, LiCF 3 CO 2,} LiAsF 6, LiSbF 6, L
iB ₁₀ Cl ₁₀ , LiAlCl ₄ , LiCl, LiBr,
LiB (C ₂ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiC ₄ F ₉ S
A solution in which an electrolyte such as O ₃ or Li (CF ₃ SO ₂ ) ₂ N is dissolved can be used. Among these, L is
A non-aqueous electrolyte solution in which iPF ₆ is dissolved is preferable. The organic solvent of the non-aqueous electrolyte may be used alone or in combination of two or more.

The solubility parameter (SP value) of the chain solvent of the non-aqueous electrolyte is 3 (MJ / SP) of the SP value of the binder resin used.
Those having a difference of m ³ ) ^1/2 or more are preferable. This difference is 3 (MJ /
m ^{3) 1/2} less affinity between the resin and the solvent is too high than, undesirable swelling of the resin is liable to occur.
The SP value of dimethyl carbonate and diethyl carbonate which are chain solvents used in the examples of the present invention is 2
It is 0.3 (MJ / m ³ ) ^1/2 and 18.0 (MJ / m ³ ) ^1/2 , and the SP value of ethylene carbonate, which is a cyclic solvent, is 30.1.
(MJ / m ³ ) ^1/2 .

The SP value of the binder resin is obtained by calculation from the chemical structure (Toshinao Okitsu: "Role of solubility parameter (SP) for 1DP21 polymer blend", 2nd Polymer Material Forum Abstracts, 167-168 ( 1993)). The SP value of the organic solvent in the electrolytic solution is a value determined purely by thermodynamics (AFM Barton, Chem. Rev., 75, 731 (197).
5); Junji Mukai, Noriyuki Kaneshiro; Practical polymer for engineers, Tokyo, Kodansha Co., Ltd., 1981, P.80-85; Kazuyuki Mihara: Commentary on paints, Tokyo, Riko Publishing Co., 1971, P. .115-116). However, the SP value of PVDF is the calculated value (14.1 (MJ / m ³ ))
^Since the difference between ^1/2 ) and the actual measurement value (23.2 (MJ / m ³ ) ^1/2 ) is large, the SP value of PVDF in the present invention is the actual measurement value.

In the non-aqueous electrolyte secondary battery of the present invention, the degree of swelling of the thermosetting binder resin in the electrolyte at 50 ° C. is preferably less than 10%, preferably less than 5%. If the thermosetting binder resin in the ideal binding state swells excessively in the electrolytic solution, the active materials are separated from each other or the active material and the current collector are separated from each other, resulting in poor contact. Further, when the adhesive force of the thermosetting binder resin is lowered in the electrolytic solution, the thermosetting binder resin peels off and causes poor contact. For this reason, it is considered that the conductivity is lowered in both cases, and the battery life is shortened due to the decrease in battery capacity and the output is lowered due to increase in internal resistance.

The thermosetting binder resin of the present invention preferably has a winding property. Negative electrode (a mixture of amorphous carbon having an average particle size of 20 μm and a thermosetting polyvinyl alcohol-based binder resin composition in a solid content volume ratio of 90:10, 150 ° C.
/ 16 mm vacuum dried) in a dry room (temperature 23 ± 2 ° C, humidity 5 ± 2%) width 60 mm x length 20
Cut it to a mm and wrap it around a stainless steel rod with a diameter of 4 mmφ with the mixture layer forming surface facing outside, and stack both ends to make 100
Attach the weight of g. This state is maintained for 1 minute, and when the appearance of defects such as cracks and wrinkles is not recognized on the surface of the mixture layer, the winding property is determined, and when the appearance defect is recognized, the winding property is determined.

[0046]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Synthesis Example 1: Synthesis of component (A) In a 1-liter separable flask equipped with a stirrer, thermometer, cooling tube, distilling tube and nitrogen gas introducing tube, polyvinyl alcohol (manufactured by Unitika Ltd., trade name: Unitika Poval UF200G, average degree of polymerization: 2000, degree of saponification: 98-99 mol%, adsorbed moisture, etc. (150 ° C on hot plate /
Drying loss for 30 minutes): 5.3% by mass) 51.01 g,
Charge 644 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) corresponding to the component (C) and 10 g of toluene, and stir at 195 ° C. over 30 minutes while stirring under a nitrogen atmosphere.
The temperature was raised to. On the way, when the temperature exceeded 185 ° C., the water in the system began to distill while azeotropically distilling with toluene. After keeping the temperature at the same temperature for 1 to 2 hours, the toluene in the system was distilled off while refluxing the toluene until the water in the system was substantially removed, and then the toluene in the system was distilled off and cooled to 120 ° C. The distillate (water content, etc.) was about 3 ml.

Then, 7.69 g of succinic anhydride was added to the dewatered solution of polyvinyl alcohol kept at 120 ° C.
(0.07 equivalent as an acid anhydride group to 1 equivalent of alcoholic hydroxyl group of polyvinyl alcohol) was added, the reaction was allowed to proceed at the same temperature for 1 hour, and then cooled to room temperature,
A component (C) solution containing 8% by mass of the component (A) was obtained. Weight average molecular weight of the obtained component (A) (measured by GPC, an aqueous solution prepared by adjusting sodium chloride to have a concentration of 0.1 mol / l as a relaxation agent was used as an eluent, and standard polyethylene oxide / polyethylene glycol was added. The value calculated as a polyethylene oxide / polyethylene glycol equivalent value) from the calibration curve prepared using is 17,000.
0, the acid value was 78 KOHmg / g. The SP value of the obtained component (A) was 25.4 (MJ / m ³ ) ^1/2 .

Preparation Example 1: Preparation of polyvinyl alcohol aqueous solution In a 0.3 liter separable flask equipped with a stirrer, thermometer, and cooling tube, 16.90 g of the same polyvinyl alcohol as used in Synthesis Example 1, pure water 183.1 g was charged, and the temperature was raised to 95 ° C. over 10 minutes while stirring.
After keeping the temperature at the same temperature for 1 hour to completely dissolve it, it was cooled to room temperature to obtain an aqueous 8% by mass polyvinyl alcohol solution.
Separately, when an attempt was made to prepare a polyvinyl alcohol NMP solution by using NMP instead of pure water, the whole system was solidified in the process of cooling to room temperature, so that it could not be prepared.

Synthesis Example 2: Synthesis of component (B) In a 0.3 liter separable flask equipped with a stirrer, thermometer, cooling tube and nitrogen gas introduction tube, a solvent-free lauryl acrylate / acrylic acid copolymer was added. (Manufactured by Soken Kagaku Co., Ltd., trade name: Actflow CBL3098, weight average molecular weight: 3100, acid value: 97 KOHmg / g) 10
9.29 g, bisphenol A type epoxy resin (manufactured by Mitsui Chemicals, Inc., trade name: EPOMIK R140P, epoxy equivalent: 187 g / eq) 70.71 g (one equivalent of carboxyl group of solvent-free lauryl acrylate / acrylic acid copolymer) On the other hand, 2 equivalents as an epoxy group) were charged, and the mixture was stirred at 150 ° C. for 10 minutes under aeration of nitrogen.
The temperature was raised to. After proceeding the reaction at the same temperature for 2 hours, 77.14 g of NMP corresponding to the component (C) was added thereto and cooled to room temperature to obtain a component (C) solution containing 70% by mass of the component (B).

The weight average molecular weight of the component (B) thus obtained (G
Measured with PC, using tetrahydrofuran as the eluent,
The value calculated as a polystyrene conversion value from a calibration curve prepared using standard polystyrene) was 21,000, the epoxy equivalent was 2377 g / eq, and the acid value was less than 1 KOHmg / g. The thermosetting property and electrolytic solution resistance of the component (A) obtained in Synthesis Example 1 were evaluated by comparison with the raw material polyvinyl alcohol. The method for producing the film and the methods for evaluating thermosetting property and electrolytic solution resistance are described below. Table 1 shows the evaluation results of thermosetting property and electrolytic solution resistance.

Preparation of Film A polyethylene terephthalate (hereinafter referred to as "PE") was prepared from a predetermined solution so that the film thickness after drying and heat treatment was about 30 μm.
Abbreviated as “T”) After uniformly casting on a film, 100 ° C.
It was dried under normal pressure on the hot plate for 1 hour. Then add this to 150
After vacuum heat treatment for 3 hours in a vacuum dryer at ℃, PE
The film was peeled from the T film and vacuum dried at 100 ° C. for 2 hours to obtain a film.

Thermosetting Evaluation Method The above-prepared film was subjected to about 3 at 25 ° C. in an absolutely dry atmosphere.
After weighing 0 mg, the sample was immersed in about 8 ml of NMP in a 13.5 ml glass screw tube, and the bottle was tightly sealed, and then heated in an oil bath at 150 ° C. for 30 minutes. A film in which the film was completely dissolved was determined to have poor thermosetting property, and a film in which the film was not dissolved and kept in its original shape was determined to be good in thermosetting property.

Electrolytic solution resistance evaluation method The above-prepared film was approximately 3 times in an absolutely dry atmosphere at 25 ° C.
Accurately weighed 0 mg, about 8 ml of a non-aqueous electrolyte solution in a 13.5 ml glass screw tube (ethylene carbonate / dimethyl carbonate / diethyl carbonate = 1/1/1 in which lithium hexafluorophosphate was dissolved at a concentration of 1 M)
(Volume ratio) Mixture, made by Kishida Chemical Co., Ltd., lithium secondary battery electrolyte grade, the same applies below) and sealed, then 25
Store separately in a constant temperature bath at 0 ° C and a constant temperature bath at 50 ° C for 24 hours. Then, the film is taken out of the non-aqueous electrolyte solution at 25 ° C. in an absolutely dry atmosphere, the non-aqueous electrolyte solution adhering to the film surface is wiped with a dry paper, and the change in mass is determined. The swelling degree with respect to the non-aqueous electrolyte was calculated from the following formula, and the value of the swelling degree at 50 ° C. was 2
If the swelling value is lower than 5 ° C, it is considered that the swelling into the non-aqueous electrolyte is considered, and the electrolyte resistance is poor. If the value of exceeds 100%, the electrolytic solution resistance is poor, 50
Electrolyte resistance is generally considered to be one in which the value of swelling degree at 0 ° C is larger than the value of swelling degree at 25 ° C and the value of swelling degree at 50 ° C is 10 to 100%.
The value of swelling degree at 50 ° C is larger than the value of swelling degree at 25 ° C and is 50 ° C
Those having a swelling value of less than 10% were judged to have good electrolytic solution resistance. Swelling degree (%) = [(mass after immersion-mass before immersion) / mass before immersion] × 100

[0054]

[Table 1] Table 1 From the above results, it can be seen that the component (A) used in the present invention has thermosetting properties and electrolytic solution resistance that cannot be obtained with the raw material polyvinyl alcohol.

Example 1 (Preparation of Thermosetting Binder Resin Composition of the Present Invention) The component (C) solution containing 8% by weight of the component (A) obtained in Synthesis Example 1 was added to 100 parts by mass in terms of the component (A). The component (C) solution containing 70% by mass of the component (B) obtained in Synthesis Example 2 was mixed with 10 parts by mass in terms of the component (B) to obtain a thermosetting binder resin composition of the present invention. The thermosetting and electrolytic solution resistance of the thermosetting binder resin composition of the present invention obtained in Example 1 were measured by PVDF.
Table 2 shows the results evaluated by comparison with.

[Table 2] Table 2 From the above results, it can be seen that the thermosetting plasticized polyvinyl alcohol-based binder resin composition of the present invention has thermosetting properties and electrolytic solution resistance that cannot be obtained by PVDF.

Example 2 (Preparation of Positive Electrode Mixture Slurry) Lithium-rich lithium manganate (Li1.12Mn1.88O4) having an average particle size of 10 μm and an average particle size of 3 μm were used as a positive electrode active material.
Of the conductive aid (artificial graphite) and the thermosetting binder resin composition obtained in Example 1 are mixed at a solid content volume ratio of 80:10:10, and NMP is added as necessary to knead the positive electrode mixture. An agent slurry was prepared.

Examples 3 and 4 and Comparative Examples 1 to 6 (Preparation of Positive Electrode Mixture Slurry) Positive electrode mixture slurries having the compositions shown in Table 3 were prepared in the same manner as in Example 2.

[0058]

[Table 3] Table 3 The conductive additive is the same as in Example 2 and the solid content volume ratio of the positive electrode active material, the conductive additive, and the binder resin composition is the same as in Example 2.

Example 5 (Preparation of Negative Electrode Mixture Slurry) Amorphous carbon having an average particle size of 20 μm as the negative electrode active material and the thermosetting plasticized polyvinyl alcohol-based binder resin composition obtained in Example 1 were used at 90:10. Was mixed at a volume ratio of solid content and kneaded while adding NMP as needed to prepare a negative electrode mixture slurry.

Example 6 and Comparative Examples 7 to 10 (Preparation of Negative Electrode Mixture Slurry) A negative electrode mixture slurry having the composition shown in Table 4 was prepared in the same manner as in Example 5.

[Table 4] Table 4 The solid content volume ratio of the negative electrode active material and the binder resin composition is the same as in Example 5.

Example 7 (Preparation of Positive Electrode) The positive electrode mixture slurry obtained in Example 2 was applied to both sides of a 20 μm thick current collector (aluminum foil) on one side.
A mixture layer was formed by coating and drying so as to be g / m ² .
Then, using a roll press machine, the mixture bulk density is 2.6 g /
It was rolled so as to have a cm ³ size and cut into a width of 54 mm to prepare a strip-shaped mixture sheet. After ultrasonically welding the collector tab made of aluminum to the edge of the mixture sheet, at 150 ℃ 1 to completely remove volatile components such as residual solvent and adsorbed moisture
It was vacuum dried for 6 hours to obtain a positive electrode.

Examples 8 and 9 and Comparative Examples 11 to 16 (Preparation of Positive Electrode) Using the positive electrode mixture slurry shown in Table 5, a positive electrode was prepared in the same manner as in Example 7.

[Table 5] Table 5

Example 10 (Preparation of Negative Electrode) The negative electrode mixture slurry obtained in Example 5 was applied to both sides of a current collector (copper foil) having a thickness of 10 μm so that the mixture coating amount was 65 g / m ^{2 on} one side. The mixture layer was applied and dried to form a mixture layer. Then, this was rolled by a roll press machine so that the mixture bulk density was 1.0 g / cm ^3, and cut into a width of 56 mm to prepare a short thin mixture sheet. An aluminum current collector tab was ultrasonically welded to the end of the mixture sheet, and then vacuum-dried at 150 ° C. for 16 hours to completely remove volatile components such as residual solvent and adsorbed water, to obtain a negative electrode.

Example 11 and Comparative Examples 17 to 20 (Preparation of Negative Electrode) Using the negative electrode mixture slurries shown in Table 6, negative electrodes were prepared in the same manner as in Example 10.

[0065]

[Table 6] Table 6 With respect to the obtained electrode, the state of the mixture layer (presence or absence of peeling, presence or absence of cracks) and appearance change after immersion in the non-aqueous electrolyte were examined. The evaluation results are shown in Table 7.

[0066]

[Table 7] Table 7 * After immersion at 50 ° C for 24 hours, observation with an electron microscope at a magnification of 1000 times "Surface coating" means that the binder covers the surface of the active material.

From the above results, comparative PVDF and (A)
The electrode using only the components cannot adhere to the adhesiveness of the mixture layer, the flexibility and the electrolytic solution resistance at the same time, whereas the electrode using the thermosetting binder resin composition of the present invention has these characteristics. I know that I can be satisfied.

Examples 12 to 18 and Comparative Examples 21 to 23 (Preparation of Lithium Secondary Battery) The positive electrodes obtained in the above Examples 7 to 9 and Comparative Examples 11 to 13 and Example 1
The negative electrodes obtained in Examples 0 and 11 and Comparative Examples 17 and 18 were combined as shown in Table 8 and wound through a polyethylene microporous membrane separator having a thickness of 25 μm and a width of 58 mm to form a spiral wound group, Insert this into the battery can, weld the nickel tab terminal that was previously welded to the copper foil of the negative electrode current collector to the bottom of the battery can, and weld the aluminum tab terminal welded to the aluminum foil of the positive electrode current collector to the lid. did. Next, non-aqueous electrolyte (1M
5m of ethylene carbonate / dimethyl carbonate / diethyl carbonate (1/1/1 (volume ratio) mixture) in which lithium hexafluorophosphate was dissolved at a concentration of 5m
After injecting l, this part is caulked and sealed, and the diameter is 18m.
A cylindrical lithium secondary battery having a height of m and a height of 65 mm was produced.

The lithium secondary batteries obtained in Examples 12 to 14 and Comparative Example 21 were charged at a constant voltage with a charging current of 400 mA and a limiting voltage of 4.2 V, and then discharged with a discharging current of 800 mA until a final voltage of 2.7 V was reached. The initial discharge capacity was measured. In addition, Example 1
The batteries obtained in 5,17 and Comparative Example 22 were subjected to constant voltage charging at a charging current of 750 mA and a limiting voltage of 4.2 V, and then discharged at a discharging current of 1500 mA until the final voltage reached 2.5 V, and the initial discharge capacity was measured. In addition, the batteries obtained in Examples 16 and 18 and Comparative Example 23 were charged at a constant voltage with a charging current of 900 mA and a limiting voltage of 4.15 V, and then discharged at a discharge current of 1800 mA until a final voltage of 3.0 V was reached to obtain an initial discharge capacity. It was measured. Charge and discharge under these conditions
70% of initial discharge capacity at an ambient temperature of 50 ° C as one cycle
Charge and discharge were repeated until the (high temperature life expiration judgment line) was cut, and the number of cycles at that time was obtained. The results are shown in Table 8.

[0070]

[Table 8] Table 8 Mn: Indicates that the positive electrode active material is lithium-rich lithium manganate. Co: Indicates that the positive electrode active material is lithium cobalt oxide. Ni: Indicates that the positive electrode active material is lithium nickel oxide. P: Indicates that the negative electrode active material is amorphous carbon. G: Indicates that the negative electrode active material is artificial graphite. PVA: shows that the binder resin composition is the product of the present invention obtained in Example 1. PVDF: Indicates that the binder resin composition is PVDF.

From Table 8, Comparative Example 21 in which a positive electrode using lithium-rich lithium manganate as an active material and PVDF as a binder resin and an anode using amorphous carbon as an active material and PVDF as a binder resin were combined. While the battery has reached the end of its life at 50 cycles, the lithium secondary battery of Examples 12 to 14 using the thermosetting binder resin composition of the present invention for at least one of the positive electrode and the negative electrode was used. It can be seen that the secondary battery has a long life of 250 cycles or more. After dismantling the battery that has expired,
In Comparative Example 21, in particular, the negative electrode material mixture layer was peeled from the copper foil of the current collector, and deposition of metallic lithium was observed in this portion, but it was not observed in the lithium secondary batteries of Examples 12 and 14. .
From the above, the lithium secondary battery using the thermosetting binder resin composition of the present invention is excellent in electrolytic solution resistance at a high temperature (50 ° C.) close to the battery upper limit temperature, and is a non-aqueous electrolytic solution. Since the swelling due to the above was extremely small, good adhesion was maintained between the interface between the current collector and the mixture layer and between the active materials in the mixture layer, and as a result, the reduction in discharge capacity was significantly reduced.

Example 19 (Preparation of thermosetting polyvinyl alcohol-based binder resin) A raw material was placed in a 0.5 liter separable flask equipped with a stirrer, a thermometer, a cooling pipe, a distilling pipe and a nitrogen gas introducing pipe. Polyvinyl alcohol (manufactured by Unitika Ltd., trade name: Unitika Poval UF200G, average degree of polymerization: 20)
00, saponification degree: 98 to 99 mol%, adsorbed water content (15
On a hot plate at 0 ° C / drying weight for 30 minutes): 6.3% by mass) 24.
2 g, solvent N-methyl-2-pyrrolidone (NMP) 3
22 g and 10 g of toluene as an azeotropic dehydration solvent were charged, and the temperature was raised to 190 ° C. over 30 minutes while stirring under aeration of nitrogen. On the way, when the temperature exceeded 180 ° C., water in the system began to distill while azeotropically distilling with toluene. 1 at the same temperature
The mixture was kept warm for ˜2 hours, and the toluene in the system was distilled off until the water content in the system was substantially eliminated. Then, the toluene in the system was distilled off and the system was cooled to 120 ° C. The distillate (water content, etc.) was about 2 ml. Then, in a dewatered aqueous solution of polyvinyl alcohol in a 120 ° C heat retention state, 2.75 g of dodecenylsuccinic anhydride (manufactured by Wako Pure Chemical Industries, Ltd., electron microscope grade) (1 equivalent of alcoholic hydroxyl group of polyvinyl alcohol, acid) 0.0 as an anhydride group
2 equivalents) was added and the reaction was allowed to proceed at the same temperature for 1 hour. Subsequently, 2.58 g of succinic anhydride (0.05 equivalent as an acid anhydride group with respect to 1 equivalent of the alcoholic hydroxyl group of polyvinyl alcohol) was added, and the reaction was allowed to proceed at the same temperature for 1 hour, then to room temperature. After cooling, the thermosetting polyvinyl alcohol-based binder resin of the present invention (NM having 8% by mass of resin content)
P solution) was obtained.

The weight average molecular weight (GP
Measured with C, 0.1 mol / mol of sodium chloride as a relaxation agent
Using an aqueous solution prepared to have a concentration of liter as an eluent, a value calculated as a polyethylene oxide / polyethylene glycol conversion value from a calibration curve prepared using standard polyethylene oxide / polyethylene glycol) was 73,000, and an acid value was 78 KOHmg / It was g. The SP value of the obtained thermosetting polyvinyl alcohol-based binder resin was 25.3 (MJ / m ³ ) ^1/2 .

The thermosetting property and electrolytic solution resistance of the product of the present invention obtained in Example 19 were evaluated by comparison with the raw materials polyvinyl alcohol and PVDF obtained in Preparation Example 1. The method for producing the film, the thermosetting property, the electrolytic solution resistance evaluation method, and the electrolytic solution resistance evaluation method are as described above. Table 9 shows the thermosetting and electrolytic solution resistance evaluation results.

[0075]

[Table 9] Table 9

From the above results, the thermosetting polyvinyl alcohol-based binder resin having the thermosetting unit represented by the general formula (III) is used as the raw material polyvinyl alcohol or PV.
It can be seen that it has thermosetting properties and electrolytic solution resistance that cannot be obtained with DF.

Example 20 (Preparation of Positive Electrode Mixture Slurry) As a positive electrode active material, lithium-rich lithium manganate (Li _1.12 Mn _1.88 O ₄ ) having an average particle size of 10 μm, and an average particle size of 3 μm
Conductive aid (artificial graphite) and the thermosetting polyvinyl alcohol-based binder resin obtained in Example 19 (resin content 8% by mass)
NMP solution) was mixed at a solid content volume ratio of 80:10:10, and kneaded while adding NMP as a solvent as needed to prepare a positive electrode mixture slurry.

Examples 21, 22 and Comparative Examples 24-26
(Preparation of Positive Electrode Mixture Slurry) A positive electrode mixture slurry having the composition shown in Table 10 was prepared in the same manner as in Example 20.

[0079]

[Table 10] Table 10 The conductive additive is the same as in Example 20. The solid content volume ratio of the positive electrode active material, the conductive additive, and the binder resin is the same as in Example 20.

Example 23 (Preparation of Negative Electrode Mixture Slurry) Amorphous carbon having an average particle size of 20 μm as the negative electrode active material and the thermosetting polyvinyl alcohol-based binder resin obtained in Example 19 (NMP having a resin content of 8% by mass). Solution) was mixed at a solid content volume ratio of 90:10, and kneaded while adding NMP as needed to prepare a negative electrode mixture slurry.

Example 24 and Comparative Examples 27 to 29 (Preparation of Negative Electrode Mixture Slurry) A negative electrode mixture slurry having the composition shown in Table 11 was prepared in the same manner as in Example 23.

[0082]

[Table 11] Table 11 The negative electrode active material and the binder resin have a solid content volume ratio of Example 2
Same as 3

Example 25 (Production of Positive Electrode) The positive electrode mixture slurry obtained in Example 20 was applied to both sides of a current collector (aluminum foil) having a thickness of 20 μm on one side 29.
The mixture layer was formed by coating and drying so that the coating amount was 0 g / m ² . Then, this was rolled by a roll press so that the mixture bulk density was 2.6 g / cm ^3, and cut into a 54 mm width to prepare a strip-shaped mixture sheet. An aluminum current collector tab was ultrasonically welded to the end of the mixture sheet, and then vacuum-dried at 150 ° C. for 16 hours to completely remove volatile components such as residual solvent and adsorbed water, to obtain a positive electrode.

Examples 26 and 27 and Comparative Examples 30 to 32
(Production of Positive Electrode) A positive electrode was produced in the same manner as in Example 25 using the positive electrode mixture slurry shown in Table 12.

[0085]

[Table 12] Table 12

Example 28 (Preparation of Negative Electrode) The negative electrode mixture slurry obtained in Example 23 was applied to both sides of a current collector (copper foil) having a thickness of 10 μm so that the mixture coating amount was 65 g / m ^{2 on} one side. The mixture layer was applied and dried to form a mixture layer. Then, this was rolled by a roll press machine so that the mixture bulk density was 1.0 g / cm ^3, and cut into a width of 56 mm to prepare a short thin mixture sheet. An aluminum current collector tab was ultrasonically welded to the end of the mixture sheet, and then vacuum-dried at 150 ° C. for 16 hours to completely remove volatile components such as residual solvent and adsorbed water, to obtain a negative electrode.

Example 29, Comparative Examples 33 to 35 (Preparation of Negative Electrode) Using the negative electrode mixture slurries shown in Table 13, negative electrodes were prepared in the same manner as in Example 28.

[0088]

[Table 13] Table 13 With respect to the obtained electrode, the state of the mixture layer (presence or absence of peeling, presence or absence of cracks) and appearance change after immersion in the non-aqueous electrolyte were examined. The evaluation results are shown in Table 14.

[0089]

[Table 14] Table 14 * Observed at 50 ° C for 24 hours and observed with an electron microscope at 1000x magnification.

From the above results, the electrode using the comparative PVDF or the raw material polyvinyl alcohol cannot achieve both the adhesiveness and flexibility of the mixture layer and the electrolytic solution resistance, while the thermosetting property of the present invention. It is understood that the electrode using the polyvinyl alcohol-based binder resin can satisfy these characteristics.

Examples 30 to 36 and Comparative Examples 36 to 38
(Preparation of lithium secondary battery) The positive electrodes obtained in Examples 25 to 27 and Comparative Examples 30 to 32 and the negative electrodes obtained in Examples 28 and 29 and Comparative Examples 33 and 34 were combined as shown in Table 15, and the thickness was set. After winding through a polyethylene microporous membrane separator having a width of 25 μm and a width of 58 mm to prepare a spiral wound group, this was inserted into a battery can,
The nickel tab terminal, which was previously welded to the copper foil of the negative electrode current collector, was welded to the bottom of the battery can, and the aluminum tab terminal welded to the aluminum foil of the positive electrode current collector was welded to the lid. Next, after injecting 5 ml of a non-aqueous electrolytic solution (a mixed solution of ethylene carbonate / dimethyl carbonate / diethyl carbonate = 1/1/1 (volume ratio) in which lithium hexafluorophosphate was dissolved at a concentration of 1 M) into a battery container, This portion was caulked and hermetically sealed to produce a cylindrical lithium secondary battery having a diameter of 18 mm and a height of 65 mm.

The lithium secondary batteries obtained in Examples 30 to 32 and Comparative Example 36 were charged at a constant voltage with a charging current of 400 mA and a limiting voltage of 4.2 V, and then discharged with a discharging current of 800 mA until a final voltage of 2.7 V was reached. The initial discharge capacity was measured. Further, the batteries obtained in Examples 33 and 35 and Comparative Example 37 were charged with a charging current.
Discharge current 1 after constant voltage charging at 750mA, 4.2V limit voltage
The initial discharge capacity was measured by discharging at 500 mA until the final voltage reached 2.5 V. In addition, Examples 34 and 36 and Comparative Example 3
The battery obtained in Example 8 was subjected to constant voltage charging at a charging current of 900 mA and a limiting voltage of 4.15 V, and then discharged at a discharge current of 1800 mA until the final voltage reached 3.0 V, and the initial discharge capacity was measured. Charging / discharging under these conditions was set as one cycle, and charging / discharging was repeated at an ambient temperature of 50 ° C until 70% of the initial discharge capacity (high temperature life expiration judgment line) was exceeded, and the number of cycles at that time was obtained.
The results are shown in Table 15.

[0093]

[Table 15] Table 15 Mn: Indicates that the positive electrode active material is lithium-rich lithium manganate. Co: Indicates that the positive electrode active material is lithium cobalt oxide. Ni: Indicates that the positive electrode active material is lithium nickel oxide. P: Indicates that the negative electrode active material is amorphous carbon. G: Indicates that the negative electrode active material is artificial graphite. PVA: indicates that the binder resin is the product of the present invention obtained in Example 19. PVDF: Indicates that the binder resin is PVDF.

From Table 15, Comparative Example 36 in which a positive electrode using lithium-rich lithium manganate as an active material and PVDF as a binder resin and an anode using amorphous carbon as an active material and PVDF as a binder resin were combined. The battery has reached the end of its life in 50 cycles, while Example 3 using the thermosetting polyvinyl alcohol-based binder resin of the present invention for at least one of the positive electrode and the negative electrode.
It can be seen that the lithium secondary batteries of 0 to 32 of the present invention have a long life of 250 cycles or more.

When the battery having a dead life was disassembled, in Comparative Example 36, the negative electrode mixture layer was peeled off from the copper foil of the current collector, particularly
Precipitation of metallic lithium was observed in this part, but it was not observed in the lithium secondary batteries of Examples 30 and 32 of the present invention. From the above, the lithium secondary battery using the thermosetting polyvinyl alcohol-based binder resin of the present invention is excellent in the electrolyte resistance at a high temperature (50 ° C.) close to the battery use upper limit temperature, and the non-aqueous electrolyte Since the swelling due to swelling was remarkably small, good adhesion was maintained at the interface between the current collector and the mixture layer and between the active materials in the mixture layer, and as a result, the reduction in discharge capacity was greatly reduced.

[0096]

INDUSTRIAL APPLICABILITY The present invention is excellent in electrolytic solution resistance at a high temperature (50 ° C.) close to the upper limit temperature of use of a lithium secondary battery, and does not cause cracking, peeling or dropping of the mixture layer in the battery manufacturing process. A thermosetting polyvinyl alcohol-based binder resin having good flexibility and flexibility can be provided. Further, by using the electrode obtained from the mixture slurry containing the thermosetting polyvinyl alcohol-based binder resin, the energy capacity in the charge / discharge cycle at 50 ° C. is reduced as compared with the conventional battery produced by using PVDF as the binder resin. It is possible to provide a non-aqueous electrolyte-based secondary battery that has a significantly reduced temperature and has a long life at high temperature.

Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) H01M 4/02 H01M 4/02 D 4/58 4/58 10/40 10/40 Z (72) Inventor Kiyotaka Mashita Ibaraki 4-13-1 Higashimachi, Hitachi, Ltd. Inside the Hitachi Chemical Co., Ltd. Research Laboratory (72) Inventor Hiroyuki Sonobe 4-13-1 Higashimachi, Hitachi City, Ibaraki Hitachi Research Institute Co., Ltd. (72) Invention Satoshi Nakazawa 4-13-1 Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Research Laboratory (72) Inventor Eisuke Haba 4-13-1, Higashimachi, Hitachi City, Ibaraki Hitachi Chemical Co., Ltd. Research Center (72) Inventor Toshihiko Ito 4-13-1, Higashi-machi, Hitachi City, Ibaraki Hitachi Chemical Co., Ltd. Yamazaki Plant (72) Inventor Shin Nishimura 7-1-1, Omika-cho, Hitachi City, Ibaraki Hitachi Mfg. Co., Ltd. Hitachi Research Laboratory (72) Inventor Tsuneo Naruzawa 7-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Co., Ltd. F-term in Hitachi Research Laboratory (reference) 4J002 BE02W BG01X BG07X FD02X GQ00 HA08 4J100 AD02P BA10H BA16H CA31 HA11 HC27 JA43 5H029 AJ03 AJ05 AK03 AL02 AL06 AL07 AL08 AL11 AL18 AM02 AM03 AM04 AM05 AM07 CJ02 AJAJH04J02 CJ22 CJ22 CJ22 C08 CA07 CA08 CA09 CB02 CB07 CB08 CB09 CB11 CB29 DA02 DA03 DA11 EA09 EA23 GA02 GA10 GA22 HA00 HA02 HA14

Claims (20)

[Claims] 1. A thermosetting polyvinyl alcohol-based binder resin, (B) an acrylic resin-based plasticizer, and (C)
A thermosetting binder resin composition comprising a solvent. 2. The thermosetting binder resin composition according to claim 1, wherein the component (A) has a thermosetting unit represented by the general formula (I). [Chemical 1] (In the formula, R represents a divalent organic group.) 3. The thermosetting binder resin composition according to claim 1, wherein the component (B) is a polymer of a monomer represented by the general formula (II) or a derivative of the polymer. . [Chemical 2] (In the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents hydrogen, a glycidyl group, or an alkyl group having 6 to 18 carbon atoms.) 4. The component (C) is a nitrogen-containing organic solvent or a mixed solvent containing the organic solvent.
The thermosetting binder resin composition according to claim 1. 5. A thermosetting binder resin composition comprising a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III) and a solvent. [Chemical 3] (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 6. The alkenyl group in the thermosetting unit is
The thermosetting binder resin composition according to claim 5, which is a dodecenyl group. 7. The solubility parameter is from 24.5 to 26.5.
A thermosetting binder resin composition comprising a thermosetting binder resin (MJ / m ³ ) ^1/2 and a solvent. 8. A mixture slurry containing the thermosetting binder resin composition according to claim 1 and a positive electrode active material or a negative electrode active material. 9. The mixture slurry according to claim 8, wherein the positive electrode active material is a lithium-containing metal composite oxide capable of reversibly inserting and releasing lithium ions by charging and discharging. 10. The mixture slurry according to claim 8, wherein the negative electrode active material is a carbon material capable of reversibly inserting and releasing lithium ions by charging and discharging. 11. An electrode obtained by applying the mixture slurry according to any one of claims 8 to 10 to a current collector and drying it. 12. A non-aqueous electrolyte secondary battery comprising the electrode according to claim 11. 13. A non-aqueous electrolyte secondary battery comprising an electrode and an electrolytic solution containing a chain organic solvent, wherein the electrode comprises a thermosetting binder resin composition and a positive electrode active material or a negative electrode active material. It is obtained by applying a mixture slurry to a current collector and drying it, and the difference between the solubility parameter (SP value) of the thermosetting binder resin and the SP value of the chain organic solvent is 3 (MJ /
m ³ ) ^1/2 or more, a non-aqueous electrolyte secondary battery. 14. The thermosetting binder resin for an electrolytic solution has a swelling degree at 50 ° C. higher than a swelling degree at 25 ° C., and a swelling degree at 50 ° C. is less than 10%. The non-aqueous electrolyte secondary battery described. 15. The non-aqueous electrolyte secondary battery according to claim 13, wherein the thermosetting binder resin has a winding property. 16. The thermosetting binder resin has the general formula (II
The non-aqueous electrolyte secondary battery according to claim 13, which is a thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by I). [Chemical 4] (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 17. The non-aqueous electrolyte secondary battery according to claim 16, wherein the alkenyl group in the thermosetting unit is a dodecenyl group. 18. A thermosetting binder resin composition,
(A) Thermosetting polyvinyl alcohol-based binder resin,
The non-aqueous electrolyte secondary battery according to claim 13, comprising (B) an acrylic resin plasticizer and (C) a solvent. 19. A thermosetting polyvinyl alcohol-based binder resin having a thermosetting unit represented by the general formula (III) for an electrode material of a non-aqueous electrolyte secondary battery. (In the formula, one of R ₃ and R ₄ represents hydrogen and the other represents an alkenyl group.) 20. The thermosetting polyvinyl alcohol-based binder resin according to claim 19, wherein the alkenyl group in the thermosetting unit is a dodecenyl group.