KR20180041091A - Binder composition for all solid state batteries - Google Patents

Abstract

A solvent for an aqueous mixture comprising a particulate copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit and a particulate fluoropolymer is solvent-exchanged with an organic solvent.

Description

Binder composition for all solid state batteries

The present invention relates to a binder composition for a full solid battery.

2. Description of the Related Art In recent years, batteries such as lithium-ion batteries have been increasingly used in various applications such as portable information terminals, portable electronic devices, and the like, small household electric power storage devices, electric motorcycles, electric vehicles and hybrid electric vehicles.

As usage increases, it is required to improve safety of a battery. In order to ensure safety, a method of preventing liquid leakage or a method of using a solid electrolyte instead of a flammable organic solvent electrolyte is effective.

As a solid electrolyte, a polymer solid electrolyte using polyethylene oxide or the like is known (Patent Document 1), but the polymer solid electrolyte is a combustible material. Further, an inorganic solid electrolyte made of an inorganic material as a solid electrolyte has also been proposed (Patent Document 2, etc.). Compared to the polymer solid electrolyte, the inorganic solid electrolyte is a solid electrolyte made of an inorganic material, which is a noncombustible material and has a very high safety as compared with a commonly used organic solvent electrolyte. As described in Patent Document 2, development of an all solid battery having high safety using an inorganic solid electrolyte has been progressing.

The entire solid battery has an inorganic solid electrolyte layer as an electrolyte layer between the positive electrode and the negative electrode. Patent Literature 3 and Patent Literature 4 disclose a method in which a slurry composition for a solid electrolyte layer containing solid electrolyte particles and a solvent is coated on a positive electrode or a negative electrode and dried to form a solid electrolyte layer, A secondary battery is described. When an electrode or an electrolyte layer is formed by a coating method, it is necessary that the viscosity and fluidity of the slurry composition containing the active material and the electrolyte are in the range of the application condition. On the other hand, an additive such as a binder other than an active material or an electrolyte is important for the electrode and the electrolyte layer formed by applying the slurry composition and drying the solvent, in order to develop the battery characteristics. Therefore, in Patent Document 5, it has been proposed to use an acrylate-based polymer for a binder.

Japanese Patent Publication No. 4134617 Japanese Patent Application Laid-Open No. 59-151770 JP-A-2009-176484 JP-A-2009-211950 International Publication No. 2011/105574

However, according to the study by the present inventors, in the all solid lithium secondary battery described in Patent Documents 3 and 4, since the ion conductivity inside the solid electrolyte layer or the inside of the active material layer is not sufficient, Patent Document 5 proposes a full-solid secondary battery having favorable battery characteristics, but a battery having higher characteristics is required.

An object of the present invention is to provide a binder composition for a full solid battery capable of producing a pre-solid battery having good battery characteristics.

As a result of intensive studies, the inventors of the present invention have found that the above objects can be achieved by mixing an aqueous dispersion of a specific copolymer and an aqueous dispersion of a specific fluorinated polymer and then performing solvent exchange with an organic solvent, thereby completing the present invention .

That is, according to the present invention,

(1) A binder composition for a full solid battery comprising a particulate copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit and a solvent of an aqueous mixture comprising the particulate fluoropolymer solvent-exchanged with an organic solvent,

(2) The binder composition for an all solid battery according to (1), wherein the content of the nitrile group-containing monomer units in the copolymer comprising the alkylene structural unit and the nitrile group-containing monomer unit is 10% by mass or more and 55%

(3) The binder composition for all-solid-state batteries as described in (1) or (2) above, wherein the iodine value of the copolymer comprising the alkylene structural unit and the nitrile group-containing monomer unit is from 3 mg / 100 mg to 30 mg /

(4) The fluorine-containing polymer according to (1)

[Chemical Formula 1]

Wherein R ₁ to R ₄ are each independently H, F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ , OCF ₃ or Cl, At least one of R ₁ to R ₄ is F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ or OCF ₃ .

(1) to (3), wherein the binder unit comprises a structural unit represented by the following formula

(1) to (4), wherein the content of the copolymer including the alkylene structural unit and the nitrile group-containing monomer unit in the whole polymer constituting the binder composition for the all-solid-state battery is from 10 mass% to 90 mass% A binder composition for a full solid battery,

(6) The binder composition for a full solid battery according to any one of (1) to (5), wherein the organic solvent is at least one selected from cyclic aliphatic hydrocarbons, aromatic hydrocarbons, ethers and esters

/ RTI >

According to the present invention, it is possible to provide a binder composition for a pre-solid battery capable of producing a pre-solid battery having good battery characteristics.

Hereinafter, the binder composition for a full solid battery of the present invention will be described. The binder composition for a full solid battery of the present invention is obtained by solvent exchange of a solvent of an aqueous mixture containing a particulate copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit and a particulate fluoropolymer with an organic solvent.

The copolymer used in the binder composition for a full solid battery of the present invention is in particulate form and includes an alkylene structural unit and a nitrile group-containing monomer unit.

(Copolymer)

Here, the copolymer is required to contain an alkylene structural unit and a nitrile group-containing monomer unit as repeating units, and optionally, a repeating unit other than an alkylene structural unit and a nitrile group-containing monomer unit (hereinafter referred to as "Quot; unit ").

(Alkylene structural unit)

The alkylene structural unit is a repeating unit composed of an alkylene structure represented by a general formula: -C _n H _2n - (wherein n is an integer of 2 or more).

Here, the alkylene structural unit may be linear or branched, but it is preferable that the alkylene structural unit is a straight chain, that is, a linear alkylene structural unit. It is also preferable that the number of carbon atoms of the alkylene structural unit is 4 or more (that is, n in the above formula is an integer of 4 or more).

The method of introducing the alkylene structural unit to the copolymer is not particularly limited. For example, there is a method in which (1) a copolymer is prepared from a monomer composition containing a conjugated diene monomer and hydrogen is added to the copolymer, A method of converting a monomer unit into an alkylene structural unit, (2) a method of preparing a copolymer from a monomer composition containing a 1-olefin monomer, and among them, (1) .

Examples of the conjugated diene monomer include conjugated diene compounds having 4 or more carbon atoms such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene. Of these, 1,3-butadiene is preferred. That is, the alkylene structural unit is preferably a structural unit (conjugated diene hydride unit) obtained by hydrogenating the conjugated diene monomer unit, and a structural unit obtained by hydrogenating 1,3-butadiene unit (1,3-butadiene hydride Unit) is more preferable. The selective hydrogenation of the conjugated diene monomer unit can be carried out using an aqueous hydrogenation method.

Examples of the 1-olefin monomer include ethylene, propylene, 1-butene, 1-hexene and the like.

These conjugated diene monomers and 1-olefin monomers may be used singly or in combination of two or more.

The content of the alkylene structural units in the copolymer is preferably 45% by mass or more and 90% by mass or less when the total amount of the repeating units (sum of the structural units and the monomer units) in the copolymer is 100% by mass More preferably 50% by mass or more and 80% by mass or less, further preferably 60% by mass or more and 75% by mass or less.

(Nitrile group-containing monomer unit)

The nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer. Since the copolymer contains a monomer unit containing a nitrile group, excellent flexibility and binding force can be exerted. Therefore, all the solid batteries produced by using the binder composition for a full solid battery of the present invention have excellent output characteristics and charge / discharge cycle characteristics.

Here, examples of the nitrile group-containing monomer capable of forming a nitrile group-containing monomer unit include an?,? - ethylenically unsaturated nitrile monomer. Specifically, the?,? - ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an?,? - ethylenically unsaturated compound having a nitrile group, and examples thereof include acrylonitrile,? -Chloroacrylonitrile, ? -Halogenoacrylonitrile such as methacrylonitrile,? -Halogenoacrylonitrile such as methacrylonitrile,? -Alkylacrylonitrile such as methacrylonitrile and? -Ethyl acrylonitrile, and the like. Of these, acrylonitrile and methacrylonitrile are preferable as the nitrile group-containing monomer from the viewpoint of enhancing the binding force of the copolymer, and acrylonitrile is more preferable. These may be used alone or in combination of two or more.

The content of the nitrile group-containing monomer units in the copolymer is preferably 10% by mass or more and 55% by mass or less, more preferably 20% by mass or less, based on 100% by mass of the total repeating units in the copolymer. Or more and 50 mass% or less, and more preferably 25 mass% or more and 40 mass% or less. When the content of the nitrile group-containing monomer units in the copolymer is within the above range, the composite has a proper affinity to the solid electrolyte, and the obtained battery has excellent output characteristics and charge / discharge cycle characteristics. When the content of the nitrile group-containing monomer units in the copolymer is within the above range, the content of the nitrile group-containing monomer units is too high, so that the phenomenon that the compounding with the fluoropolymer becomes insufficient can be suppressed. In addition, since the content of the monomer unit containing a nitrile group is too low, the phenomenon that the affinity with the solid electrolyte becomes insufficient can be suppressed.

(Other repeating units)

Other repeating units other than the above-mentioned alkylene structural units and nitrile group-containing monomer units are not particularly limited and include repeating units derived from known monomers copolymerizable with the above-mentioned monomers, such as (meth) acrylic acid ester monomers Unit and a hydrophilic group-containing monomer unit. Examples of other repeating units include aromatic vinyl monomer units derived from aromatic vinyl monomers such as styrene,? -Methylstyrene, butoxystyrene, and vinylnaphthalene.

These monomers may be used singly or in combination of two or more. In the present invention, "(meth) acryl" means acryl and / or methacryl.

Examples of the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, Acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, n-butyl methacrylate, Butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methane But are not limited to, acrylate, methacrylate, acrylate, acrylate, acrylate, acrylate, isoleucyl acrylate, Methacrylic acid alkyl esters such as stearyl methacrylate; and the like.

Examples of the hydrophilic group-containing monomer capable of forming a hydrophilic group-containing monomer unit include a polymerizable monomer having a hydrophilic group. Specifically, examples of the hydrophilic group-containing monomer include a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and a monomer having a hydroxyl group.

Examples of the monomer having a carboxylic acid group include a monocarboxylic acid, a dicarboxylic acid, an acid anhydride thereof, and derivatives thereof.

Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid.

Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, and the like.

Examples of the dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, methylallyl maleate, diphenylmaleic acid maleate, maleic acid dicylate, Maleic acid monoethyl, monobutyl maleate, dibutyl maleate, monoethyl maleate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, fumaric acid, maleic acid dodecyl maleate, monoethyl maleate, monoethyl maleate, Monocyclohexyl dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, dibutyl itaconate, and the like. Examples of the acid anhydrides of dicarboxylic acids include maleic anhydride, acrylic acid anhydride, methyl maleic anhydride, and dimethyl maleic anhydride.

As the monomer having a carboxylic acid group, an acid anhydride which generates a carboxyl group by hydrolysis can also be used.

Examples of the monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth) allylsulfonic acid, styrenesulfonic acid, ethyl (meth) acrylate-2-sulfonate, -Hydroxypropanesulfonic acid and the like. In the present invention, "(meth) allyl" means allyl and / or methallyl.

Examples of the monomer having a phosphoric acid group include (meth) acryloyloxyethyl phosphate, methyl 2- (meth) acryloyloxyethyl phosphate and ethyl- (meth) acryloyloxyethyl phosphate. In the present invention, "(meth) acryloyl" means acryloyl and / or methacryloyl.

Examples of the monomer having a hydroxyl group include ethylenically unsaturated alcohols such as (meth) allyl alcohol, 3-buten-1-ol and 5-hexen-1-ol; Hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di- St. alkanol esters of unsaturated carboxylic acids; the formula: of ^{_{CH 2 = CR 1 -COO- (C}} q H 2q O) p -H ( wherein, p is an integer of 2 ~ 9, q is 2 to 4 integer, R ¹ represents a hydrogen or a methyl group), polyalkyl esters of alkylene glycol and (meth) acrylic acid represented by the following; 2-hydroxyethyl-2 '- (meth) acryloyloxyethyl phthalate, 2-hydroxyethyl (Meth) acrylate of dihydroxy esters of dicarboxylic acids such as ethyl-2 '- (meth) acryloyloxy succinate (Meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-2-hydroxypropyl ether, (Meth) allyl-3-hydroxybutyl ether, (meth) allyl-2-hydroxybutyl ether, Mono (meth) allyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether; polyoxyalkylene glycol mono (Meth) allyl ethers, such as glycerol mono (meth) allyl ether, (meth) allyl-2-chloro-3-hydroxypropyl ether, ) ≪ / RTI > of the halogen and hydroxy substituents of alkylene glycol (Meth) allyl-2-hydroxyethylthioether, (meth) allyl-2-heptyl, di (meth) allyl ether, (Meth) allylthioethers of alkylene glycols such as methyl (meth) acrylate and ethyl (meth) acrylate, and the like.

The content of other repeating units in the copolymer is preferably 25% by mass or less, more preferably 10% by mass or less, still more preferably 1% by mass or less, and the copolymer contains other repeating units Is particularly preferable. That is, the copolymer is preferably composed of only an alkylene structural unit and a nitrile group-containing monomer unit.

The iodine value of the copolymer is preferably 3 mg / 100 mg or more and 30 mg / 100 mg or less, more preferably 5 mg / 100 mg or more and 20 mg / 100 mg or less. If the iodine value of the copolymer is within the above range, the copolymer can be chemically structurally stable over a high electric field, and the electrode structure can be maintained even in a long-term cycle, so that a battery having excellent charge-discharge cycle characteristics can be provided. When the iodine value of the copolymer falls within the above range, the phenomenon that the stability at the oxidation potential becomes insufficient because the iodine value is too high can be suppressed. Further, the iodine value can be obtained in accordance with JIS K6235; 2006.

(Method for preparing copolymer)

The method for preparing the above-mentioned copolymer is not particularly limited. For example, the monomer composition containing the above-mentioned monomer is optionally polymerized in the presence of a chain transfer agent to obtain a copolymer, and then the resulting copolymer is hydrogenated ).

The content of each monomer in the monomer composition used for preparing the copolymer may be determined in accordance with the content of each repeating unit in the copolymer.

Any polymerization method such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used without particular limitation. As the polymerization reaction, any reaction such as ionic polymerization, radical polymerization, and living radical polymerization can be used.

Of these, the emulsion polymerization method is preferable in that the copolymer is obtained in a state in which the copolymer is dispersed in an aqueous solvent as it is. Here, the water-based solvent is a water-containing solvent, and water is preferable from the viewpoint that there is no flammability and a dispersion of the copolymer is easily obtained.

Furthermore, water may be used as a main solvent and an aqueous solvent other than water may be mixed in the range in which the effect of the present invention is not adversely affected and the dispersion state of the copolymer can be ensured. Examples of the aqueous solvent other than water include ketones, alcohols, glycols, glycol ethers and ethers.

The emulsion polymerization can be carried out according to a conventional method. When emulsion polymerization is carried out, conventionally used polymerization additives such as emulsifiers, polymerization initiators, molecular weight regulators or chain transfer agents can be used.

As the emulsifier, any one can be used as long as a desired polymer can be obtained. Examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants. Of these, anionic surfactants such as alkylbenzenesulfonic acid salts, aliphatic sulfonic acid salts, sulfuric acid ester salts of higher alcohols,? -Olefin sulfonic acid salts and alkyl ether sulfuric acid ester salts can be preferably used.

The amount of the emulsifier is arbitrary as long as a desired polymer can be obtained. The amount of the emulsifier is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the monomer composition, 5 parts by mass or less.

As the polymerization initiator to be used in the polymerization reaction, any one can be used as long as a desired polymer can be obtained. Examples of the polymerization initiator include sodium persulfate (NaPS), ammonium persulfate (APS), potassium persulfate .

In the polymerization, the polymerization system may contain a molecular weight regulator or a chain transfer agent. Examples of the molecular weight adjuster or chain transfer agent include n-hexylmercaptan, n-octylmercaptan, t-octylmercaptan, n-dodecylmercaptan, t-dodecylmercaptan and n-stearylmercaptan. Xanthan gum compounds such as dimethyl mercaptan, alkyl mercaptan, dimethyl xanthogen disulfide and diisopropyl xanthogen disulfide, terpinolene, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetramethyl thiuram monosulfide Phenol-based compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, dichloromethane, dibromomethane, carbon tetrabromide Halogenated hydrocarbon compounds such as thioglycolic acid, thiomalic acid, 2-ethylhexyl thioglycolate, diphenylethylene and? -Methylstyrene dimer. Among them, from the viewpoint of inhibition of side reaction, alkyl mercaptan is preferable, and t-dodecyl mercaptan is more preferable. These may be used singly or in combination of two or more in an arbitrary ratio.

When a chain transfer agent is used, the chain transfer agent is preferably used in an amount of 0.1 part by mass or more, more preferably 0.15 part by mass or more, and more preferably 0.6 part by mass or less, per 100 parts by mass of the total amount of the monomers in the monomer composition More preferably 0.5 parts by mass or less.

When polymerization is carried out, seed polymerization may be carried out by employing seed particles. The polymerization conditions may also be arbitrarily selected depending on the polymerization method and the kind of the polymerization initiator.

Further, the hydrogenation method of the polymer is not particularly limited, but for example, the aqueous layer hydrogenation method described in International Publication No. 2013/080989 and Japanese Patent Laid-Open Publication No. 2013-8485 is preferable, and the aqueous direct hydrogenation method is more preferable .

In the aqueous direct hydrogenation method, the concentration of the unsaturated polymer in the aqueous layer (concentration in the dispersion liquid state) is preferably 40 mass% or less in order to prevent aggregation.

The hydrogenation catalyst to be used is not particularly limited as long as it is a compound which is not decomposed well in water. Specific examples of the hydrogenation catalyst include palladium catalysts of carboxylic acids such as formic acid, propionic acid, lauric acid, succinic acid, oleic acid and phthalic acid; palladium chloride, ) Palladium, palladium chloride such as ammonium hexachloropalladium (IV), iodide such as palladium iodide, palladium sulfate dihydrate and the like. Particularly preferred among these are palladium salts of carboxylic acids, dichloro (norbornadiene) palladium and hexachloropalladium (IV) ammonium. The amount of the hydrogenation catalyst to be used may be appropriately determined, but is preferably 5 to 6000 ppm, more preferably 10 to 4000 ppm, in terms of the metal amount of the hydrogenation catalyst, relative to the amount of the unsaturated polymer to be hydrogenated.

The reaction temperature in the aqueous direct hydrogenation method is preferably 0 to 300 캜, more preferably 20 to 150 캜, particularly preferably 30 to 100 캜. When the reaction temperature is in the above range, the phenomenon that the reaction rate is lowered because the reaction temperature is too low can be suppressed, and the phenomenon of side reactions such as the hydrogenation reaction of the nitrile group is suppressed because the reaction temperature is too high . The hydrogen pressure is preferably 0.1 to 30 MPa, more preferably 0.5 to 20 MPa. The reaction time is selected in consideration of the reaction temperature, the hydrogen pressure, and the hydrogenation rate of the target.

In the aqueous direct hydrogenation method, after completion of the reaction, the hydrogenation catalyst in the dispersion is removed. For example, a method of adding an adsorbent such as activated carbon or an ion exchange resin to adsorb the hydrogenation catalyst under stirring, followed by filtration or centrifugation of the dispersion may be employed.

The copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit used in the present invention is in a particulate form and is used in a state (aqueous dispersion) in which it is dispersed in an aqueous solvent.

(Fluorine-based polymer)

The fluorine-based polymer used in the present invention includes a structural unit represented by the following general formula (1).

(2)

Wherein R ₁ to R ₄ are each independently H, F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ , OCF ₃ or Cl, At least one of R ₁ to R ₄ is F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ or OCF ₃ .

Among them, a vinylidene fluoride polymer, a hexafluoropropylene polymer, a tetrafluoroethylene polymer, a vinylidene fluoride-hexafluoropropylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and the like are preferable, and vinylidene fluoride Polymer, and vinylidene fluoride-hexafluoropropylene copolymer are more preferable.

(Method for preparing fluoropolymer)

The method for preparing the above fluoropolymer is not particularly limited, but an emulsion polymerization method is preferable. The emulsion polymerization method is a method of obtaining a fluoropolymer by using a monomer, an emulsifier, an aqueous solvent, a polymerization initiator, and a chain transfer agent optionally used. Here, the water-based solvent is a solvent containing water, and water is preferable from the viewpoint that there is no flammability and a dispersion of the polymer is easily obtained.

Further, water may be used as a main solvent and an aqueous solvent other than water may be mixed and used within the range in which the effect of the present invention is not deteriorated and the dispersion state of the polymer can be ensured. Examples of the aqueous solvent other than water include ketones, alcohols, glycols, glycol ethers and ethers.

The emulsifier is not particularly limited as long as it can form micelles and can stably disperse the resulting fluorine-based polymer. Any of an ionic surfactant, a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, Or a plurality of types may be used in combination.

The surfactants used in the emulsion polymerization are conventionally used conventionally for the polymerization of vinylidene fluoride polymers such as perfluorinated, partially fluorinated, and nonfluorinated surfactants. Among them, it is preferable to use a fluorinated surfactant having a perfluoroalkylsulfonic acid and a salt thereof, a perfluoroalkylcarboxylic acid and a salt thereof, a fluorocarbon chain or a fluoropolyether chain, and it is preferable to use a perfluoroalkylcarboxylic acid It is more preferable to use a carboxylic acid and a salt thereof.

Among the surfactants used in emulsion polymerization, non-fluorinated surfactants include, for example, 3-allyloxy-2-hydroxy-1-propanesulfonic acid salt, polyvinylphosphonic acid, polyacrylic acid, polyvinylsulfonic acid, And salts thereof, polyethylene glycols and / or polypropylene glycols and their block copolymers, alkylphosphonates and siloxane-based surfactants, and the like.

When a chain transfer agent is used for preparing the fluorine-based polymer, the chain transfer agent is preferably used in an amount of 0.1 part by mass or more, more preferably 0.15 part by mass or more per 100 parts by mass of the total amount of the monomers in the monomer composition , Preferably 0.6 mass part or less, more preferably 0.5 mass part or less.

When emulsion polymerization is carried out, an inorganic salt may be added to the reaction system to effect copolymerization in the presence of an inorganic salt. Particularly, when a surfactant and an inorganic salt are used in combination, formation of aggregates during polymerization can be effectively inhibited , It is possible to narrow the particle diameter distribution. Specific examples of the inorganic salt include alkali metal salts such as sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, sodium phosphate, sodium hydrogen phosphate and sodium tripolyphosphate; , And barium sulfate; alkaline earth metal salts such as aluminum sulfate and aluminum chloride; Among these, an alkali metal salt is preferable, and sodium hydrogen phosphate is more preferable. The amount of the inorganic salt to be used is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass based on 100 parts by mass of the monomer mixture. When the amount of the inorganic salt to be used is within the above range, the amount of the inorganic salt to be used is too small to suppress the phenomenon that the effect of the addition is not manifested well, and the amount of the inorganic salt to be used is too large, The phenomenon can be suppressed. The method of adding the inorganic salt is not particularly limited, and it can be added to the reaction system as a whole, dividedly, or continuously.

As the polymerization initiator used in the emulsion polymerization, a redox initiator system such as ascorbic acid-hydrogen peroxide is used in addition to a water-soluble peroxide or a water-soluble azo-based compound.

The fluorine-based polymer used in the present invention is in a particulate form and is used in a state of being dispersed in an aqueous solvent (aqueous dispersion).

(Aqueous mixture)

The aqueous mixture used in obtaining the binder composition for a full solid battery of the present invention is obtained by mixing the aqueous dispersion of the particulate copolymer containing the alkylene structural unit and the nitrile group-containing monomer unit obtained above and the aqueous dispersion of the particulate fluoropolymer . That is, the solvent of the aqueous mixture is an aqueous solvent such as water.

 (Binder composition for all solid batteries)

The binder composition for a full solid battery of the present invention is obtained by solvent exchange of an aqueous solvent which is a solvent of an aqueous mixture with an organic solvent. Here, the solvent exchange can be carried out by a known method. For example, an aqueous mixture and an organic solvent may be put into a rotary evaporator, and the solvent may be exchanged and dehydrated at a predetermined temperature under reduced pressure.

The copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit contained in the binder composition for a pre-solid-state battery is in a state dissolved in an organic solvent, and the fluoropolymer is in a particulate form without being dissolved in an organic solvent. Specifically, the fluorine-based polymer is formed by aggregating a plurality of individual particles to form secondary particles, and the secondary particles include a copolymer containing an alkylene structural unit dissolved in an organic solvent and a monomer containing a nitrile group-containing monomer unit (Polymeric composite) of a fluoropolymer and a copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit is formed.

That is, the binder composition for a pre-solid battery in which a solvent of an aqueous mixture comprising a particulate copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit and a particulate fluoropolymer solvent is replaced with an organic solvent is preferably a particulate fluoropolymer , And a copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit bonded to the particulate fluoric polymer.

The binder composition for a full solid battery of the present invention has excellent strength and high affinity with a solid electrolyte. Further, when the binder composition for a full solid battery of the present invention is used, solid electrolyte particles, an active material and the like can be bonded to each other. Therefore, the internal resistance can be reduced, and the resulting pre-solid battery has excellent output characteristics. Furthermore, since the binder composition for a full solid battery of the present invention has high binding force, deterioration of the solid electrolyte layer can be suppressed. Therefore, the pre-solid battery obtained has excellent charge-discharge cycle characteristics.

The content of the copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit in the whole polymer constituting the binder composition for a full solid battery of the present invention is preferably 10% by mass or more and 90% by mass or less, more preferably Is not less than 15 mass% and not more than 75 mass%, more preferably not less than 20 mass% and not more than 60 mass%. When the content of the copolymer including the alkylene structural unit and the nitrile group-containing monomer unit in the whole polymer is within the above range, the copolymer is chemically structurally stable over the high electric potential, and the electrode structure can be maintained even in a long-term cycle , It is possible to provide a battery excellent in charge-discharge cycle characteristics. When the content of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit in the whole polymer is in the above range, the content ratio of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit is too high , The phenomenon that the strength of the polymer composite material becomes insufficient can be suppressed. In addition, since the content of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit is too low, it is possible to suppress the phenomenon that the binding force of the polymer conjugate becomes insufficient.

(Organic solvent)

Examples of the organic solvent which can be used for the solvent exchange include cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alicyclic hydrocarbons such as dimethyl ether, methyl ethyl ether, diethyl ether and cyclopentyl methyl ether; Ethers, and esters such as ethyl acetate and butyl acetate are preferable, and toluene and xylene are more preferable. These solvents may be used alone or in combination of two or more.

(All solid batteries)

By using the binder composition for a full solid battery of the present invention as a binder in at least one layer, preferably all layers, of at least a positive electrode active material layer, a negative electrode active material layer, or a solid electrolyte layer, a positive electrode having a positive electrode active material layer, And a solid electrolyte cell having a solid electrolyte layer between these positive electrode active material layers are obtained. The positive electrode has a positive electrode active material layer on the current collector, and the negative electrode has a negative electrode active material layer on the current collector. Hereinafter, the solid electrolyte layer, the positive electrode active material layer, and the negative electrode active material layer will be described.

(Solid electrolyte layer)

The solid electrolyte layer is formed by applying a slurry composition for a solid electrolyte layer containing solid electrolyte particles and a binder onto a later-described positive electrode active material layer or a negative electrode active material layer and drying the slurry composition. The slurry composition for a solid electrolyte layer is prepared by mixing solid electrolyte particles, a binder, an organic solvent and other components added as needed.

(Solid electrolyte particle)

The solid electrolyte is particulate because it is subjected to a pulverizing process, but it is amorphous, not completely spherical. Generally, the size of the fine particles is measured by a method of irradiating the particles with laser light to measure scattered light, and the particle size in this case is a value assuming that the shape of the particle is spherical. When a plurality of particles are combined and measured, the presence ratio of particles having an equivalent particle diameter can be expressed as a particle size distribution. The solid electrolyte particle forming the solid electrolyte layer is a value measured by this method, and is often expressed as an average particle diameter.

The average particle diameter of the solid electrolyte particles is preferably 0.3 to 1.3 탆 from the viewpoint of obtaining a slurry composition for a solid electrolyte layer having good dispersibility and coatability. The average particle diameter of the solid electrolyte particles is the number average particle diameter that can be obtained by measuring the particle size distribution by laser diffraction.

The solid electrolyte particle is not particularly limited as long as it has lithium ion conductivity, but it preferably contains a crystalline inorganic lithium ion conductor or an amorphous inorganic lithium ion conductor.

Examples of the crystalline inorganic lithium ion conductor include Li ₃ N, LISICON (Li ₁₄ Zn (GeO ₄ ) ₄ ), perovskite type Li _0.5 La _0.5 TiO ₃ , LIPON (Li _{3 + y} PO _{4 -x} N _x ) -LISICON (Li _3.25 Ge _0.25 P _0.75 S ₄ ).

The amorphous inorganic lithium ion conductor is not particularly limited as long as it contains S (sulfur atom) and has ion conductivity (a sulfide solid electrolyte material). Here, in the case where the all-solid-state cell in which the binder for the all-solid-state cell of the present invention is used is a solid-state lithium secondary battery, as a sulfide solid electrolyte material to be used, Li ₂ S and a sulfide of elements of Groups 13 to 15 Based on the total weight of the composition. As a method for synthesizing a sulfide solid electrolyte material using such a raw material composition, for example, an amorphization method can be mentioned. Examples of the amorphization method include a mechanical milling method and a melt quenching method, among which a mechanical milling method is preferable. According to the mechanical milling method, processing at room temperature can be performed, and the manufacturing process can be simplified.

Examples of the elements of Groups 13 to 15 include Al, Si, Ge, P, As, Sb and the like. Specific examples of the sulfides of the elements of Groups 13 to 15 include Al ₂ S ₃ , SiS ₂ , GeS ₂ , P ₂ S ₃ , P ₂ S ₅ , As ₂ S ₃ , Sb ₂ S _3, etc. . Among them, it is preferable to use a sulfide of Group 14 or Group 15. Particularly, a sulfide solid electrolyte material comprising Li ₂ S and a raw material composition containing a sulfide of an element of Groups 13 to 15 is used as the Li ₂ S-P ₂ S ₅ material, the Li ₂ S-SiS ₂ material , A Li ₂ S-GeS ₂ material, or a Li ₂ S-Al ₂ S ₃ material, and more preferably a Li ₂ S-P ₂ S ₅ material. This is because they have excellent Li ion conductivity.

It is preferable that the sulfide solid electrolyte material has a crosslinked sulfur. This is because the ionic conductivity is enhanced by having crosslinked sulfur. Furthermore, when the sulfide solid electrolyte material has crosslinked sulfur, the reactivity with the positive electrode active material is high, and a high resistance layer is liable to be generated. However, in the present invention, since a binder composition comprising a fluoropolymer and a copolymer of a copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit is used, it is possible to suppress the generation of a high- The effect can be sufficiently exhibited. The "having bridged sulfur" can also be determined by taking into account, for example, the result of measurement by Raman spectroscopy, the composition ratio of raw materials, the measurement result by NMR, and the like.

The mole fraction of Li ₂ S in the Li ₂ S-P ₂ S ₅ material or the Li ₂ S-Al ₂ S ₃ material is, for example, from the viewpoint of obtaining a sulfide solid electrolyte material having a crosslinked sulfur more reliably It is preferably in the range of 50 to 74%, and more preferably in the range of 60 to 74%.

The sulfide solid electrolyte material may be a sulfide glass or a crystallized sulfide glass obtained by heat-treating the sulfide glass. The sulfide glass can be obtained, for example, by the amorphization method described above. The crystallized sulfide glass can be obtained, for example, by heat treatment of the glass sulfide.

In particular, it is preferable that the sulfide solid electrolyte material is a crystallized sulfide glass represented by Li ₇ P ₃ S ₁₁ . This is because Li ion conductivity is particularly excellent. As a method of synthesizing Li ₇ P ₃ S ₁₁ , for example, Li ₂ S and P ₂ S ₅ are mixed at a molar ratio of 70:30 and amorphized by a ball mill to synthesize sulfide glass, and the obtained sulfide glass is heated at 150 ° C. Li ₇ P ₃ S ₁₁ can be synthesized by heat treatment at ~ 360 ° C.

(bookbinder)

As the binder, other polymer may be contained in addition to the above-described binder composition for a full solid battery. When another polymer is used as the binder, the other polymer may be mixed with the above-described binder composition for a pre-solid battery at the time of preparing the slurry composition for a solid electrolyte layer.

Here, other polymers capable of functioning as a binder together with the above-described binder composition for all-solid-state cells are not particularly limited, and acrylate polymers such as butyl acrylate and ethyl acrylate can be cited.

(Organic solvent)

As the organic solvent, those exemplified in the above-mentioned binder composition for a whole solid battery can be used.

The slurry composition for a solid electrolyte layer may contain, in addition to the above components, other components to be added as needed, such as a dispersing agent, a leveling agent, and a component having a function of a defoaming agent. These components are not particularly limited as long as they do not affect the cell reaction.

(Dispersant)

As the dispersing agent, an anionic compound, a cationic compound, a nonionic compound, and a polymer compound are exemplified. The dispersing agent is selected according to the solid electrolyte particles to be used. The content of the dispersant in the slurry composition for a solid electrolyte layer is preferably within a range not affecting the battery characteristics, specifically 10 parts by mass or less based on 100 parts by mass of the solid electrolyte particles.

(Leveling agent)

Examples of the leveling agent include surfactants such as alkyl surfactants, silicone surfactants, fluorochemical surfactants, and metal surfactants. By mixing the surfactant, it is possible to prevent cratering that occurs when the slurry composition for a solid electrolyte layer is applied to the surface of the positive electrode active material layer or the negative electrode active material layer described later, and the smoothness of the negative electrode can be improved. The content of the leveling agent in the slurry composition for a solid electrolyte layer is preferably within a range not affecting the battery characteristics, specifically 10 parts by mass or less based on 100 parts by mass of the solid electrolyte particles.

(Antifoaming agent)

Examples of the antifoaming agent include a mineral oil type antifoaming agent, a silicone type antifoaming agent and a polymer type antifoaming agent. The antifoaming agent is selected according to the solid electrolyte particles to be used. The content of the defoaming agent in the slurry composition for a solid electrolyte layer is preferably within a range not affecting the battery characteristics, specifically 10 parts by mass or less based on 100 parts by mass of the solid electrolyte particles.

(Positive electrode active material layer)

The positive electrode active material layer is formed by applying a slurry composition for a positive electrode active material layer containing a positive electrode active material, solid electrolyte particles and a positive electrode binder onto a surface of a current collector described later and drying. A slurry composition for a positive electrode active material layer is prepared by mixing a positive electrode active material, solid electrolyte particles, a positive electrode binder, an organic solvent and other components added as needed.

(Positive electrode active material)

The positive electrode active material is a compound capable of absorbing and desorbing lithium ions. The positive electrode active material is roughly classified into an inorganic compound and an organic compound.

Examples of the positive electrode active material composed of an inorganic compound include transition metal oxides, complex oxides of lithium and transition metals, and transition metal sulfides. As the transition metal, Fe, Co, Ni, Mn and the like are used. Specific examples of the inorganic compound used for the positive electrode active material include lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ and LiFeVO ₄ ; transition metals such as TiS ₂ , TiS ₃ and amorphous MoS ₂ Transition metal oxides such as metal sulfides, Cu ₂ V ₂ O ₃ , amorphous V ₂ O-P ₂ O ₅ , MoO ₃ , V ₂ O ₅ and V ₆ O ₁₃ . These compounds may be partially substituted with an element.

Examples of the positive electrode active material composed of an organic compound include polyaniline, polypyrrole, polyacene, disulfide compound, polysulfide compound, N-fluoropyridinium salt and the like. The positive electrode active material may be a mixture of the inorganic compound and the organic compound.

The average particle diameter of the positive electrode active material used in the present invention can be obtained from the viewpoints of improvement of the battery characteristics such as the load characteristics and the charge and discharge cycle characteristics and also the ability to obtain a full solid secondary battery having a large charge- From the viewpoint of ease of handling in the production and handling of the positive electrode and the handling thereof in producing the positive electrode, it is usually 0.1 to 50 탆, preferably 1 to 20 탆. The average particle diameter can be determined by measuring the particle size distribution by laser diffraction.

(Solid electrolyte particle)

As the solid electrolyte particles, the same materials as those exemplified in the solid electrolyte layer can be used.

The weight ratio of the positive electrode active material to the solid electrolyte particles is preferably the positive electrode active material: solid electrolyte particles = 90:10 to 50:50, and more preferably the positive electrode active material: solid electrolyte particles = 60:40 to 80:20. When the weight ratio of the positive electrode active material is within this range, the weight ratio of the positive electrode active material is too small, so that the amount of the positive electrode active material in the battery is reduced, thereby suppressing the phenomenon of deterioration of capacity as a battery. If the weight ratio of the solid electrolyte particles is within this range, the weight ratio of the solid electrolyte particles is too small, so that the sufficient conductivity can not be obtained and the positive electrode active material can not be effectively used. As a result, .

(Binder for positive electrode)

As the binder for the positive electrode, the same materials as those exemplified for the solid electrolyte layer can be used.

The content of the positive electrode binder in the slurry composition for positive electrode active material layer is preferably 0.1 to 100 parts by mass of the positive electrode active material in terms of solid content from the viewpoint of preventing deterioration of the positive electrode active material from the electrode without inhibiting the cell reaction To 5 parts by mass, more preferably 0.2 to 4 parts by mass.

As the organic solvent in the slurry composition for a positive electrode active material layer and other components added as needed, the same components as those exemplified in the solid electrolyte layer can be used. The content of the organic solvent in the slurry composition for positive electrode active material layer is preferably 20 to 80 parts by mass, more preferably 20 to 80 parts by mass, per 100 parts by mass of the positive electrode active material, from the viewpoint of obtaining good paint characteristics while maintaining the dispersibility of the solid electrolyte. Is 30 to 70 parts by mass.

The slurry composition for a positive electrode active material layer may contain, in addition to the above components, other components added as necessary, and an additive that exhibits various functions such as a conductive agent and a reinforcing agent. They are not particularly limited as long as they do not affect the cell reaction.

(Conductive agent)

The conductive agent is not particularly limited as long as it can impart conductivity, but usually includes carbon powder such as acetylene black, carbon black and graphite, and fibers and foils of various metals.

(reinforcement)

As the reinforcing material, various inorganic and organic fillers such as spherical, plate, rod-like or fibrous fillers can be used.

(Negative electrode active material layer)

The negative electrode active material layer includes a negative electrode active material.

(Negative electrode active material)

Examples of the negative electrode active material include carbon alloys such as graphite and coke. The negative electrode active material comprising the carbon isotope may be used in the form of a mixture with a metal, a metal salt, an oxide or the like, or a coating. Examples of the negative electrode active material include oxides and sulfates of silicon, tin, zinc, manganese, iron and nickel, metal lithium, lithium alloys such as Li-Al, Li-Bi-Cd and Li-Sn-Cd, , Silicon, and the like can be used. In the case of a metal material, a metal foil or a metal plate may be used directly as an electrode, but it may be a particulate form.

In this case, the negative electrode active material layer is formed by applying a negative electrode active material layer slurry composition comprising a negative electrode active material, solid electrolyte particles and a negative electrode binder onto a surface of a current collector to be described later and drying. The slurry composition for a negative electrode active material layer is prepared by mixing a negative electrode active material, a solid electrolyte particle, a negative electrode binder, an organic solvent and other components added as necessary. The solid electrolyte particles in the slurry composition for negative electrode active material layer, the organic solvent and other components to be added as needed may be the same as those exemplified in the above positive electrode active material layer.

When the negative electrode active material is in a particulate form, the average particle diameter of the negative electrode active material is usually 1 to 50 탆, preferably 15 to 30 탆, from the viewpoint of improving the battery characteristics such as initial efficiency, load characteristics, and charge-discharge cycle characteristics.

The weight ratio of the negative electrode active material to the solid electrolyte particles is preferably 90:10 to 50:50, and more preferably 60:40 to 80:20, as negative electrode active material: solid electrolyte particles. When the weight ratio of the negative electrode active material is within this range, the weight ratio of the negative electrode active material is too small, so that the amount of the negative electrode active material in the battery is reduced, thereby suppressing the phenomenon of leading to a capacity drop as a battery. If the weight ratio of the solid electrolyte particles is within this range, the weight ratio of the solid electrolyte particles is too small, so that the sufficient conductivity is not obtained and the negative electrode active material can not be effectively used. As a result, .

(Negative electrode binder)

When the negative electrode active material is in a particulate form, the negative electrode binder may be the same one as exemplified for the solid electrolyte layer.

When the negative electrode active material is in the form of a particle, the content of the negative electrode binder in the slurry composition for negative electrode active material layer is preferably in the range of the solid content equivalent to 100 parts by mass of the negative electrode active material from the viewpoint of preventing deterioration of the electrode active material from the electrode, Preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 4 parts by mass.

(Whole house)

The current collector used for forming the positive electrode active material layer and the negative electrode active material layer is not particularly limited as long as it has electric conductivity and is electrochemically durable. However, from the viewpoint of heat resistance, , Nickel, stainless steel, titanium, tantalum, gold, and platinum are preferable. Among them, aluminum is particularly preferable for positive electrode, and copper is particularly preferable for negative electrode. Although the shape of the current collector is not particularly limited, it is preferably a sheet shape having a thickness of about 0.001 to 0.5 mm. The current collector is preferably subjected to surface roughening in advance in order to increase the bonding strength with the above-described positive and negative electrode active material layers. Examples of the roughening method include mechanical roughening, electrolytic roughening, and chemical roughening. In mechanical polishing, a wire brush having a polishing pad, a grindstone, an emery pad, a steel wire, or the like to which abrasive particles are fixed is used. The intermediate layer may be formed on the surface of the current collector in order to improve the bonding strength and conductivity between the current collector and the positive and negative electrode active material layers.

(Production of slurry composition for solid electrolyte layer)

The slurry composition for a solid electrolyte layer is obtained by mixing the aforementioned solid electrolyte particles, a binder, an organic solvent and other components added as needed.

(Production of slurry composition for positive electrode active material layer)

The slurry composition for positive electrode active material layer is obtained by mixing the above-mentioned positive electrode active material, solid electrolyte particles, positive electrode binder, organic solvent and other components added as needed.

(Production of slurry composition for negative electrode active material layer)

The slurry composition for negative electrode active material layer is obtained by mixing the above-mentioned negative electrode active material, solid electrolyte particles, negative electrode binder, organic solvent and other components added as needed.

The method of mixing the slurry composition is not particularly limited, and examples thereof include a method using a mixing device such as a stirring type, shaking type, and rotary type. A method of using a dispersion kneading apparatus such as a homogenizer, a ball mill, a bead mill, a planetary mixer, a sand mill, a roll mill, and a planetary kneader may be used, and the aggregation of the solid electrolyte particles can be suppressed , A method using a planetary mixer, a ball mill or a bead mill is preferable.

(Preparation of all solid batteries)

The positive electrode in the all-solid-state cell is produced by applying the slurry composition for positive electrode active material layer onto a current collector and drying to form a positive electrode active material layer. The negative electrode in all the solid batteries can be used as it is when the metal foil is used. When the negative electrode active material is in a particulate form, the slurry composition for a negative electrode active material layer is coated on a current collector different from that of the positive electrode and dried to form a negative electrode active material layer. Subsequently, a slurry composition for a solid electrolyte layer is applied onto the formed positive electrode active material layer or negative electrode active material layer, followed by drying to form a solid electrolyte layer. Then, an electrode in which a solid electrolyte layer is not formed and an electrode in which the solid electrolyte layer is formed are bonded to each other to manufacture an all solid state battery element.

The method of applying the slurry composition for a positive electrode active material layer and the slurry composition for a negative electrode active material layer to a current collector is not particularly limited and may be selected from the group consisting of a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, Or the like. The amount to be applied is not particularly limited, but is an amount such that the thickness of the active material layer formed after removing the organic solvent is usually 5 to 300 占 퐉, preferably 10 to 250 占 퐉. The drying method is not particularly limited, and examples thereof include hot air, hot air, low-humidity air drying, vacuum drying, and drying by irradiation with (circle) infrared rays or electron beams. The drying conditions are adjusted so that the organic solvent is volatilized as soon as possible in a speed range where stress concentration generally occurs and cracks are generated in the active material layer or the active material layer is not peeled off from the current collector. Further, the electrode may be stabilized by pressing the dried electrode. The pressing method includes a method such as a mold press or a calender press, but is not limited thereto.

The drying temperature is a temperature at which the organic solvent is sufficiently volatilized. Specifically, it is preferably 50 to 250 占 폚, more preferably 80 to 200 占 폚, from the viewpoint that a good active material layer can be formed without thermal decomposition of the binder for positive electrode and negative electrode. The drying time is not particularly limited, but is usually in the range of 10 to 60 minutes.

The method of applying the slurry composition for a solid electrolyte layer to the positive electrode active material layer or the negative electrode active material layer is not particularly limited and is carried out by the same method as the above-described application method for the slurry composition for positive electrode active material layer and the slurry composition for negative electrode active material layer However, the gravure process is preferable from the viewpoint that a solid electrolyte layer of a thin film can be formed. The amount to be applied is not particularly limited, but is an amount such that the thickness of the solid electrolyte layer formed after removing the organic solvent is usually 2 to 20 μm, preferably 3 to 15 μm. The drying method, the drying conditions and the drying temperature are the same as those of the above-described slurry composition for positive electrode active material layer and slurry composition for negative electrode active material layer.

Furthermore, the laminate obtained by bonding the electrode on which the solid electrolyte layer is formed and the electrode on which the solid electrolyte layer is not formed may be pressed. The pressing method is not particularly limited, and examples thereof include a flat plate press, a roll press, and a CIP (Cold Isostatic Press). The pressure to be applied under pressure is preferably from 5 to 700 MPa, more preferably from 5 to 700 MPa, from the viewpoint of the resistance at the interface between the electrode and the solid electrolyte layer, and hence the contact resistance between the particles in each layer, Is 7 to 500 MPa.

The slurry composition for a solid electrolyte layer is applied to either the positive electrode active material layer or the negative electrode active material layer, but it is preferable to apply the slurry composition for a solid electrolyte layer to the active material layer having a larger particle diameter of the electrode active material to be used. If the particle size of the electrode active material is large, unevenness is formed on the surface of the active material layer, so that the unevenness of the surface of the active material layer can be alleviated by applying the slurry composition. Therefore, when the electrode on which the solid electrolyte layer is formed and the electrode on which the solid electrolyte layer is not formed are stacked and laminated, the contact area between the solid electrolyte layer and the electrode becomes large, and the interface resistance can be suppressed.

The obtained all-solid-state battery element is placed in a battery container in a state of being in a state of being left unchanged, such as by winding or folding, and then pinched to obtain an all-solid battery. If necessary, it is also possible to prevent the rise of the internal pressure of the battery and the overcharge discharge by inserting an overcurrent prevention element such as an expanded metal, a fuse, a PTC element, or the like into a battery container. The shape of the battery may be a coin type, a button type, a sheet type, a cylindrical shape, a square shape, or a flat shape.

Example

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples at all. Each characteristic is evaluated by the following method. In the present embodiment, "parts" and "%" are "parts by mass" and "% by mass", respectively, unless otherwise specified.

≪ Measurement of iodine value >

The iodine value was obtained according to JIS K 6235 (2006).

<Battery characteristics: output characteristics>

A 5-cell all-solid secondary battery was charged to 4.3 V by a constant current method of 0.1 C and then discharged to 0.1 V at 3.0 V to obtain a 0.1 C discharge capacity a. Thereafter, the battery was charged up to 4.3 V at 0.1 C, and then discharged to 3.0 V at 5 C to obtain a 5 C discharge capacity b. (B / a (%)) of the electric capacity of the 5 C discharge capacity b and the 0.1 C discharge capacity a, as the measurement value of the average value of the five cells. The larger this value is, the better the output characteristic is.

A: Capacity retention rate is 90% or more

B: Capacity retention rate is 80% or more and less than 90%

C: Capacity retention ratio is 70% or more and less than 80%

D: Capacity retention rate is less than 70%

<Battery characteristics: charging / discharging cycle characteristics>

The obtained pre-solid secondary battery was charged at a constant current of 4.2 V at a constant current of 0.5 C at 25 DEG C, charged at a constant voltage, and charged at a constant current of 3.0 V at a constant current of 0.5 C V was carried out. The charge-discharge cycle was performed up to 50 cycles, and the ratio of the discharge capacity per 50 cycles to the initial discharge capacity was obtained as the capacity retention rate. The larger this value is, the better the charge-discharge cycle characteristic is.

A: Capacity retention rate is 85% or more

B: Capacity retention rate is 70% or more and less than 85%

C: Capacity retention rate is 50% or more and less than 70%

D: Capacity retention rate is less than 50%

(Example 1)

<Preparation of Copolymer Containing Alkylene Structural Unit and Nitrile Group-Containing Monomer Unit>

In an autoclave equipped with a stirrer, 240 parts of ion-exchanged water, 2.5 parts of sodium alkylbenzenesulfonate as an emulsifier, 35 parts of acrylonitrile as a nitrile group-containing monomer and 0.25 parts of t-dodecylmercaptan as a chain transfer agent were put in this order, After nitrogen substitution, 65 parts of 1,3-butadiene as a conjugated diene monomer was pressed, and 0.25 part of ammonium persulfate as a polymerization initiator was added, and polymerization reaction was carried out at a reaction temperature of 40 캜. Then, a copolymer of acrylonitrile and 1,3-butadiene was obtained. The polymerization conversion rate was 85%.

Ion exchange water was added to the obtained copolymer to obtain a solution in which the total solid content concentration was adjusted to 12 mass%. 400 mL of the obtained solution (total solid content: 48 g) was placed in an autoclave equipped with a stirrer having a volume of 1 L and nitrogen gas was flowed for 10 minutes to remove dissolved oxygen in the solution. Then, 75 mg of palladium acetate as a catalyst for hydrogenation was dissolved in palladium ) Dissolved in 180 mL of ion-exchanged water to which 4-fold molar amount of nitric acid had been added. After the inside of the system was replaced with hydrogen gas twice, the content of the autoclave was heated to 50 占 폚 in a state of being pressurized to 3 MPa with hydrogen gas, and hydrogenation reaction (hydrogenation reaction in the first step) was carried out for 6 hours.

Subsequently, the autoclave was returned to atmospheric pressure, and again 25 mg of palladium acetate as a catalyst for hydrogenation reaction was added to dissolve in 60 mL of ion-exchanged water to which 4-fold molar amount of nitric acid was added relative to Pd. After the inside of the system was replaced with hydrogen gas twice, the content of the autoclave was heated to 50 DEG C under a pressure of 3 MPa with hydrogen gas, and hydrogenation reaction (hydrogenation reaction in the second step) was carried out for 6 hours.

Thereafter, the contents were returned to room temperature, the inside of the system was brought to a nitrogen atmosphere, and the mixture was concentrated to a solid content concentration of 40% using an effervescent device to obtain an aerial image containing an alkylene structural unit and a nitrile group- To obtain a coalesced aqueous dispersion. The iodine value of the copolymer was 7 mg / 100 mg.

&Lt; Preparation of fluoropolymer &gt;

Into an autoclave equipped with a stirrer, 330 parts of ion-exchanged water and 0.2 part of sodium hydrogen phosphate were put in this order and the inside was purged with nitrogen. Then, 1 part of ammonium perfluorooctanoate, 0.25 parts of ethyl acetate and 36.7 parts of vinylidene fluoride were added, 0.06 part of ammonium persulfate was added as a polymerization initiator, and polymerization reaction was carried out at 80 캜. The supercritical pressure at this time was 3.2 MPa. 63.3 parts of vinylidene fluoride were continuously introduced so that the pressure was maintained at a point where the pressure dropped to 2.5 MPa. The polymerization reaction was terminated when the pressure was lowered to 1.5 MPa to obtain a vinylidene fluoride polymer (PVDF). The solid content concentration of the aqueous dispersion of the obtained vinylidene fluoride polymer was 18.5%.

&Lt; Preparation of binder composition &gt;

500 parts of xylene was added to a mixture of 21.9 parts of the aqueous dispersion of the copolymer containing the obtained alkylene structural units and nitrile group-containing monomer units and 87.9 parts of the aqueous dispersion of PVDF as the fluorine-based polymer obtained, and the mixture was dispersed in a water bath Was reduced to 80 DEG C, and solvent exchange and dehydration operations were carried out.

A xylene dispersion of a complex comprising a copolymer containing an alkylene structural unit having a water concentration of 42 ppm, a solid content concentration of 8.0 wt%, and a nitrile group-containing monomer unit, and a fluorine polymer was obtained by dehydration. The proportion of the copolymer including the alkylene structural unit and the nitrile group-containing monomer unit in the whole polymer was 35%.

&Lt; Preparation of slurry composition for positive electrode active material layer &

(Li ₂ S / P ₂ S ₅ = 70 mol% / 30 mol%) consisting of Li ₂ S and P ₂ S ₅ as solid electrolyte particles, 100 parts of lithium cobalt oxide (average particle diameter: 11.5 μm) , Number average particle diameter: 0.4 占 퐉), 13 parts of acetylene black as a conductive agent, and a copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit, and a fluorine-based polymer, , And 1 part of a polymer having Mw = 150000 in which butyl acrylate and ethyl acrylate were copolymerized at 60/40. Then, the solid content was adjusted to 78% with xylene as an organic solvent, followed by mixing with a planetary mixer for 60 minutes did. Further, the solid content was adjusted to 74% with xylene and then mixed for 10 minutes to prepare a slurry composition for positive electrode active material layer.

&Lt; Preparation of slurry composition for negative electrode active material layer &

(Li ₂ S / P ₂ S ₅ = 70 mol% / 30 mol%, number average (number average particle diameter: 20 μm)) composed of Li ₂ S and P ₂ S ₅ as solid electrolyte particles, Manufactured by Nippon Polyurethane Industry Co., Ltd.), 50 parts of a copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit, and a fluorine-based polymer in an amount of 3 parts by mass corresponding to the solid content and a mixture of butyl acrylate and ethyl acrylate 1 part of Mw = 150000 copolymerized with propylene glycol monomethyl ether and 60/40 was further mixed. Then, xylene was added as an organic solvent to adjust the solid content to 60%, followed by mixing with a planetary mixer to prepare a slurry composition for negative electrode active material layer.

&Lt; Preparation of Slurry Composition for Solid Electrolyte Layer &gt;

(Li ₂ S / P ₂ S ₅ = 70 mol% / 30 mol%, number average particle diameter: 1.2 μm, cumulative 90% particle diameter: 2.1 μm) composed of Li ₂ S and P ₂ S ₅ as solid electrolyte particles, , 3 parts of a xylene dispersion of a complex comprising a copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit and a fluoropolymer-containing equivalent, 3 parts of butyl acrylate and ethyl acrylate of 60/40 And 1 part of copolymerized Mw = 150000 were mixed. Then, xylene was added as an organic solvent to adjust the solid concentration to 30%, followed by mixing with a planetary mixer to prepare a slurry composition for a solid electrolyte layer.

&Lt; Preparation of all solid secondary battery &

The slurry composition for positive electrode active material layer was applied to the surface of the current collector and dried (110 DEG C, 20 minutes) to form a positive electrode active material layer having a thickness of 50 mu m to prepare a positive electrode. The slurry composition for negative electrode active material layer was applied to the surface of another current collector and dried (110 DEG C, 20 minutes) to form a negative electrode active material layer having a thickness of 30 mu m to prepare a negative electrode.

Then, the slurry composition for a solid electrolyte layer was coated on the surface of the positive electrode active material layer and dried (110 DEG C, 10 minutes) to form a solid electrolyte layer having a thickness of 18 mu m.

A solid electrolyte layer laminated on the surface of the positive electrode active material layer was adhered to the negative electrode active material layer of the negative electrode and pressed to obtain a pre-solid secondary battery. The thickness of the solid electrolyte layer of the all-solid secondary battery after pressing was 11 mu m. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

(Example 2)

Except that 25 parts of acrylonitrile as a nitrile group-containing monomer and 75 parts of 1,3-butadiene as a conjugated diene monomer were used in the preparation of a copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit, 1, a copolymer was prepared. The iodine value of this copolymer was 8 mg / 100 mg. Furthermore, the preparation of the binder composition was carried out in the same manner as in Example 1 except that the proportion of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit in the whole polymer was 25% in the preparation of the binder composition did. A pre-solid secondary battery was produced in the same manner as in Example 1 except for the above. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

(Example 3)

Except that 40 parts of acrylonitrile as a nitrile group-containing monomer and 60 parts of 1,3-butadiene as a conjugated diene monomer were used in the preparation of a copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit, 1, a copolymer was prepared. The iodine value of this copolymer was 7 mg / 100 mg. Further, the preparation of the binder composition was carried out in the same manner as in Example 1 except that the proportion of the copolymer containing the alkylene structural unit and the nitrile group-containing monomer unit in the whole polymer was 45% in preparation of the binder composition did. A pre-solid secondary battery was produced in the same manner as in Example 1 except for the above. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

(Comparative Example 1)

The procedure of Example 1 was repeated except that an aqueous dispersion of hydrogenated SBR (H-SBR) was used in place of the aqueous dispersion of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit in the preparation of the binder composition To prepare a binder composition. The iodine value of H-SBR was 6 mg / 100 mg. A pre-solid secondary battery was produced in the same manner as in Example 1 except that the obtained binder composition was used. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

(Comparative Example 2)

Except that the aqueous dispersion of the copolymer containing an alkylene structural unit and a nitrile group-containing monomer unit was not used in the preparation of the binder composition and only the aqueous dispersion of the fluorinated polymer was used, The preparation was carried out. A pre-solid secondary battery was produced in the same manner as in Example 1 except that the obtained binder composition was used. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

(Comparative Example 3)

In the preparation of the binder composition, a xylene solution of a hydrogenated nitrile-butadiene copolymer (iodine value: 7 mg / 100 mg) was used as a solid component instead of an aqueous dispersion of a copolymer containing an alkylene structural unit and a nitrile group- A binder composition was prepared in the same manner as in Example 1 except that the additive was added. A pre-solid secondary battery was produced in the same manner as in Example 1 except that the obtained binder composition was used. This battery was used to evaluate the output characteristics and the charge-discharge cycle characteristics. The results are shown in Table 1.

As shown in Table 1, a binder composition for a full solid battery comprising a particulate copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit and a solvent of an aqueous mixture containing a particulate fluoropolymer solvent exchanged with an organic solvent , All of the output characteristics and the charge-discharge cycle characteristics were good.

Claims (6)

A binder composition for a full solid battery, comprising a particulate copolymer comprising an alkylene structural unit and a nitrile group-containing monomer unit, and a solvent of an aqueous mixture comprising the particulate fluoropolymer solvent-exchanged with an organic solvent. The method according to claim 1,
Wherein the content of the nitrile group-containing monomer unit in the copolymer including the alkylene structural unit and the nitrile group-containing monomer unit is 10% by mass or more and 55% by mass or less. 3. The method according to claim 1 or 2,
Wherein the iodine content of the copolymer comprising the alkylene structural unit and the nitrile group-containing monomer unit is 3 mg / 100 mg or more and 30 mg / 100 mg or less. 4. The method according to any one of claims 1 to 3,
Wherein the fluorine-based polymer is represented by the general formula (1)
(3)

Wherein R ₁ to R ₄ are each independently H, F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ , OCF ₃ or Cl, At least one of R ₁ to R ₄ is F, CF ₃ , CH ₂ CF ₃ , CF ₂ CF ₃ , CF ₂ CF ₂ CF ₃ , OCF ₂ CF ₂ CF ₃ or OCF ₃ .
And a structural unit represented by the following general formula (1). 5. The method according to any one of claims 1 to 4,
Wherein the content of the copolymer including the alkylene structural unit and the nitrile group-containing monomer unit in the whole polymer constituting the binder composition for a solid-state battery is 10% by mass or more and 90% by mass or less. 6. The method according to any one of claims 1 to 5,
Wherein the organic solvent is at least one selected from cyclic aliphatic hydrocarbons, aromatic hydrocarbons, ethers and esters.