Electrolyte composition, cured electrolyte obtained by curing the same, electrode, and secondary battery

Abstract

An electrolyte composition that contains a fluorine-based polymer, a photocurable and / or thermocurable monomer, an alkali metal salt, and a salt-dissociating agent, wherein the total amount of the fluorine-based polymer and the monomer is 10 mass% or greater with respect to the total amount of the fluorine-based polymer, the monomer, the alkali metal salt, and the salt-dissociating agent.

Description

[Technical Field]

[0001] The present invention relates to an electrolyte composition, a cured electrolyte obtained by curing the same, an electrode, and a secondary battery. [Background technology]

[0002] In recent years, in secondary batteries such as lithium ion secondary batteries, it has been proposed to improve the safety of the battery itself by replacing the electrolyte from a non-aqueous electrolytic solution containing a carbonate-based organic solvent as a main component with a gel or solid polymer electrolyte.

[0003] For example, Patent Document 1 discloses an electrolyte composition containing an alkali metal salt, a photo- and / or thermosetting monomer, and a salt dissociating agent, in which the content of the alkali metal salt is 50 mass% or more relative to 100 mass% of the total amount of the alkali metal salt, the photo- and / or thermosetting monomer, and the salt dissociating agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 026702 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the electrolyte membrane obtained by curing the electrolyte composition disclosed in Patent Document 1 is susceptible to short-circuiting due to the growth of alkali metal dendrites in, for example, a current test performed over multiple cycles, and there is concern about insufficient membrane strength, so there is room for improvement.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to improve the film strength of the electrolyte cured product as much as possible while maintaining high lithium ion conductivity. [Means for solving the problem]

[0007] In order to achieve the above object, the electrolyte composition according to the present invention is an electrolyte composition comprising a fluoropolymer, a photo- and / or thermosetting monomer, an alkali metal salt, and a salt dissociating agent, wherein the total amount of the fluoropolymer and the monomer is 10 mass % or more based on the total amount of the fluoropolymer, the monomer, the alkali metal salt, and the salt dissociating agent.

[0008] The content of the fluoropolymer may be 70% by mass or more based on the total amount of the fluoropolymer and the monomer.

[0009] The alkali metal salt may include a lithium salt represented by the following formula (1). LiN(SO2R 1 )(SO2R 2 ) (1) (R 1 and R 2 represents a fluorine atom or a fluoroalkyl group having 1 to 3 carbon atoms.

[0010] The fluorine-based polymer may contain vinylidene fluoride as a constituent unit.

[0011] The above monomer may contain a urethane bond as a constituent unit.

[0012] The salt dissociating agent may include at least one of a sulfonyl compound, a carbonate compound, and a nitrile compound.

[0013] The salt dissociating agent may include a sulfonyl compound.

[0014] The present invention also provides a cured electrolyte product obtained by curing the electrolyte composition having the above-described structure, which has a lithium ion conductivity of 2.1×10 -4 (S / cm) or more.

[0015] The electrode according to the present invention is characterized in that it is formed using the electrolyte composition having the above-described structure.

[0016] The secondary battery according to the present invention is characterized by being formed using the electrolyte cured product having the above-described configuration and / or the electrode having the above-described configuration. [Effects of the Invention]

[0017] According to the present invention, the electrolyte contains a fluorine-based polymer, a photo- and / or thermo-curable monomer, an alkali metal salt, and a salt dissociating agent, and the total amount of the fluorine-based polymer and the monomer is 10 mass% or more based on the total amount of the fluorine-based polymer, the monomer, the alkali metal salt, and the salt dissociating agent. This makes it possible to improve the film strength of the cured electrolyte as much as possible while maintaining high lithium ion conductivity. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail. Note that the following description of the embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0019] The electrolyte composition of this embodiment contains a fluoropolymer, a photo- and / or thermo-curable monomer, an alkali metal salt, and a salt dissociator. In the electrolyte composition of this embodiment, the total amount of the fluoropolymer and the photo- and / or thermo-curable monomer relative to the total amount of the fluoropolymer, the photo- and / or thermo-curable monomer, the alkali metal salt, and the salt dissociator has a lower limit of preferably 10% by mass or more, more preferably 15% by mass or more, and an upper limit of preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. This can improve the film strength of the cured electrolyte obtained by curing the electrolyte composition. From the viewpoint of improving breaking strength, the total amount of the fluorine-based polymer and the photo- and / or thermosetting monomer (total content when two or more types are used in combination) is preferably 5% by mass or more, more preferably 10% by mass or more, and the upper limit is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, based on the total amount of the components constituting the electrolyte composition of this embodiment (100% by mass). In addition, in the electrolyte composition of this embodiment, the content of the fluorine-based polymer is preferably 70% by mass or more, based on the total amount of the fluorine-based polymer and the photo- and / or thermosetting monomer. Furthermore, the cured electrolyte obtained by curing the electrolyte composition of this embodiment has an ionic conductivity of 2.1 × 10 -4 (S / cm) or more.

[0020] Each component in the electrolyte composition of this embodiment will be described below.

[0021] <Alkali metal salts> The alkali metal salt is not particularly limited, and examples of alkali metals constituting the alkali metal salt include lithium, sodium, potassium, rubidium, cesium, and francium. Preferred are lithium, sodium, and potassium, and more preferred is lithium.

[0022] Examples of alkali metal salts include alkali metal salts of fluorosulfonic acid such as LiFSO3, alkali metal salts of trifluoromethanesulfonic acid such as LiCF3SO3, imide-based alkali metal salts such as LiN(FSO2)2, alkali metal salts of perfluoroalkanesulfonylmethides such as LiC(CF3SO2)3, and LiPF a (C m F 2m+1 ) 6-a (0≦a≦6, 1≦m≦2) and other fluorophosphates, alkali metal perchlorates such as LiClO4, LiBF b (C n F 2n+1 ) 4-b (0≦b≦4, 1≦n≦2), alkali metal salts of oxalatoborates such as LiBOB, cyanoborates such as lithium tetracyanoborate, and alkali metal salts such as LiAsF, LiI, and LiSbF. These alkali metal salts may be used alone or in combination of two or more.

[0023] The alkali metal salt preferably includes an imide-based alkali metal salt such as LiN(FSO2)2, and more preferably includes a lithium salt represented by the following formula (1) (hereinafter also referred to as a "sulfonylimide compound"). LiN(SO2R 1 )(SO2R 2 ) (1) (R 1 and R 2 represents a fluorine atom or a fluoroalkyl group having 1 to 3 carbon atoms.

[0024] where R 1 and R 2 The fluoroalkyl group having 1 to 3 carbon atoms in the formula (I) may be a hydrocarbon group having 1 to 3 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom. Specific examples of the fluoroalkyl group include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, and a pentafluoroethyl group. 1 and R 2is preferably a fluorine atom, a trifluoromethyl group, or a pentafluoroethyl group, more preferably a fluorine atom or a trifluoromethyl group, and most preferably a fluorine atom.

[0025] Specific examples of sulfonylimide compounds (lithium salts) include lithium bis(fluorosulfonyl)imide (LiN(FSO), hereinafter also referred to as "LiFSI"), lithium bis(trifluoromethylsulfonyl)imide (LiN(CFSO), hereinafter also referred to as "LiTFSI"), lithium (fluorosulfonyl)(methylsulfonyl)imide, lithium (fluorosulfonyl)(ethylsulfonyl)imide, lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide, lithium (fluorosulfonyl)(pentafluoroethylsulfonyl)imide, lithium (fluorosulfonyl)(heptafluoropropylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, and lithium bis(heptafluoropropylsulfonyl)imide. These sulfonylimide compounds may be used alone or in combination of two or more.

[0026] The compound represented by the above formula (1) is preferably LiN(FSO2)2, LiN(CF3SO2)2, or LiPF6, more preferably LiN(FSO2)2 or LiN(CF3SO2)2, and most preferably LiN(FSO2)2.

[0027] The sulfonylimide compound may be a commercially available product or may be synthesized by a conventionally known method. The method for synthesizing the sulfonylimide compound is not particularly limited, and any conventionally known method may be employed. For example, WO 2011 / 149095, JP 2014-201453 A, JP 2010-168249 A, JP 2010-168308 A, JP 2010-189372 A, WO 2011 / 065502, JP-T-8-511274 A, WO 2012 / 108284, WO 2012 / 117961, WO 2012 / 118063, JP 2010-280586 A, JP 2010-254543 A, JP 2007-182410, and WO 2010 / 010613 A methods described therein can be mentioned. By the above-mentioned conventionally known method, a powder (solid) of the sulfonylimide compound can be obtained.

[0028] From the viewpoint of improving the charge / discharge efficiency and its retention rate of the battery, the content of the alkali metal salt (total content when two or more types are used in combination) is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the entire electrolyte composition (100% by mass of the total amount of the components constituting the electrolyte composition of the present embodiment), and the upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. Note that when the alkali metal salt contains only a sulfonylimide compound, the content of the alkali metal salt is interpreted as the content of the sulfonylimide compound. The content of the alkali metal salt (the sulfonylimide compound) is particularly preferably 10% by mass or more and 80% by mass or less.

[0029] <Fluorine-based polymer> The fluoropolymer contains vinylidene fluoride as a structural unit, and is composed of, for example, polyvinylidene fluoride (PVDF), PVDF-hexafluoropropylene (HFP), PVDF-trifluoroethylene (vinylidene fluoride-trifluoroethylene copolymer), PVDF-ter-trifluoroethylene-ter-chlorotrifluoroethylene (vinylidene fluoride-ter-trifluoroethylene-ter-chlorotrifluoroethylene copolymer), PVDF-ter-trifluoroethylene-ter-1,1-chlorofluoroethylene (vinylidene fluoride-ter-trifluoroethylene-ter-1,1-chlorofluoroethylene copolymer), etc. In particular, copolymers such as PVDF-HFP (vinylidene fluoride-hexafluoropropylene copolymer) are preferred as the fluoropolymer. These fluoropolymers may be used alone or in combination of two or more.

[0030] The fluoropolymer preferably has a weight-average molecular weight of 50,000 to 1,000,000, more preferably 200,000 to 1,000,000, and even more preferably 300,000 to 1,000,000. A weight-average molecular weight of 50,000 or more further improves film formability when forming a film using the composition. A weight-average molecular weight of 1,000,000 or less further prevents the film from hardening, resulting in excellent ionic conductivity. The weight-average molecular weight can also be evaluated by measuring the melt flow index (10 min) at 230°C under a load of 10 kg in accordance with ASTM D1238 (ISO 1133). The MFI measured under these conditions can be between 0.2 g / 10 min and 20 g / 10 min, preferably between 0.5 g / 10 min and 10 g / 10 min.

[0031] From the viewpoint of improving the breaking strength, the content of the fluorine-based polymer (total content when two or more types are used in combination) relative to the entire electrolyte composition (100% by mass of the total amount of the components constituting the electrolyte composition of the present invention) has a lower limit of preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and most preferably 15% by mass or more, and an upper limit of preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0032] In addition, in the electrolyte composition of the present embodiment, from the viewpoint of improving the breaking strength, the content of the fluorine-based polymer (total content when two or more types are used in combination) relative to the total amount of the fluorine-based polymer and the photo- and / or thermosetting monomer has a lower limit of preferably 50 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more, and an upper limit of preferably 99 mass % or less, more preferably 95 mass % or less.

[0033] <Photo- and / or thermosetting monomer> The photo- and / or thermosetting monomer is not particularly limited as long as it has a functional group that can be polymerized by light and / or heat. Examples of the functional group include a polymerizable unsaturated group, an epoxy group, and an isocyanate group. The photo- and / or thermosetting monomer preferably has a hetero element. Here, examples of the hetero element include nitrogen, oxygen, sulfur, phosphorus, chlorine, iodine, and bromine, with oxygen and nitrogen being preferred, and oxygen being more preferred. The photo- and / or thermosetting monomer may have one polymerizable functional group or two or more polymerizable functional groups. From the viewpoint of improving the film strength of the cured electrolyte material as much as possible, the photo- and / or thermosetting monomer is preferably a polyfunctional monomer having two or more polymerizable functional groups.

[0034] Examples of monofunctional monomers having one polymerizable functional group include alkyl (meth)acrylates having a substituent such as methyl (meth)acrylate, ethyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; alkoxy (poly)alkylene glycol (meth)acrylates such as methoxy (poly)ethylene glycol (meth)acrylate, methoxy (poly)propylene glycol (meth)acrylate, and phenoxyethylene glycol (meth)acrylate; carboxyl group-containing monomers such as 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl tetrahydrophthalate, and (meth)acrylic acid; monofunctional epoxy compounds such as butyl glycidyl ether, tert-butyl glycidyl ether, benzyl glycidyl ether, and 2-ethylhexyl glycidyl ether; and monofunctional allyl ether compounds such as ethylene glycol monoallyl ether.

[0035] Examples of polyfunctional monomers having two or more polymerizable functional groups include 1,3-butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)ethylene (poly)propylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and ethoxylated glycerin. Polyfunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate, (poly)ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, (poly)propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, epoxybutene, 3,4-epoxy-1-pentene, 1,2-epoxy-5,9-cyclododecadiene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5-cyclooctene, vinyl glycidyl ether, allyl glycidyl ether, 4-vinylcyclohexyl glycidyl ether, α-terpenyl glycidyl ether, cyclohexenyl methyl glycidyl ether, 4-vinylbenzyl glycidyl ether, 4-allylbenzyl glycidyl ether, allyl glycidyl ether, ethylene glycol allyl glycidyl ether, ethylene glycol vinyl glycidyl ether, diethylene glycol allyl glycidyl ether, diethylene glycol vinyl glycidyl ether, triethylene glycol allyl glycidyl ether, triethylene glycol vinyl glycidyl ether Examples of suitable epoxy compounds include polyfunctional epoxy compounds such as oligoethylene glycol allyl glycidyl ether and oligoethylene glycol vinyl glycidyl ether, polyfunctional vinyl compounds such as vinyloxyethyl (meth)acrylate, vinyloxyethoxyethyl (meth)acrylate and 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, cyanate group-containing compounds such as 2-(meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate and m-isopropenyl-α,α-dimethylbenzyl isocyanate, and urethane acrylates having a urethane bond and an acrylate group.

[0036] The above-mentioned monofunctional monomers and polyfunctional monomers may be used alone or in combination of two or more kinds.

[0037] The photo- and / or thermosetting monomer preferably contains a urethane bond as a constituent unit, such as urethane acrylate, which can improve the film strength of the cured electrolyte obtained by curing the electrolyte composition due to hydrogen bonding between the urethane bonds.

[0038] The content of the photo- and / or thermosetting monomer (total content when two or more types are used in combination) relative to the total amount of the fluorine-based polymer and the photo- and / or thermosetting monomer, from the viewpoint of improving breaking strength, is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less, and the lower limit is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Furthermore, from the viewpoint of improving breaking strength, the content of the photo- and / or thermosetting monomer (total content when two or more types are used in combination) relative to the entire electrolyte composition (100% by mass of the total amount of the components constituting the electrolyte composition of the present invention) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and the upper limit is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0039] The photo- and / or thermosetting monomer preferably has a molecular weight of 50 to 4,000, more preferably 50 to 3,800, and even more preferably 50 to 3,500, from the viewpoint of improving breaking strength.

[0040] <Salt dissociator> The salt dissociating agent is not particularly limited as long as it promotes the dissociation of alkali metal salts into ions, but a compound having a hetero element is preferred. Examples of compounds having a hetero element include carbonate compounds, nitrile compounds, sulfonyl compounds, carboxylic acid anhydrides, sulfate ester compounds, thioether compounds, sulfite ester compounds, and nitrogen-containing cyclic compounds. Furthermore, the salt dissociating agent is preferably a compound having a boiling point of 100°C or higher, more preferably a compound having a boiling point of 150°C or higher, and even more preferably a compound having a boiling point of 200°C or higher. These salt dissociating agents may be used alone or in combination of two or more. Among these salt dissociating agents, carbonate compounds, nitrile compounds, and sulfonyl compounds are preferred, sulfonyl compounds and nitrile compounds are more preferred, and sulfonyl compounds are even more preferred, from the viewpoint of further promoting the dissociation of alkali metal salts into ions and improving the ionic conductivity and transport number of alkali metal cations. That is, the salt dissociating agent contains at least one of a sulfonyl compound, a carbonate compound, and a nitrile compound.

[0041] Examples of carbonate compounds include cyclic carbonates such as ethylene carbonate (EC), vinylene carbonate (VC), vinylethylene carbonate (VEC), methylvinylene carbonate (MVC), and ethylvinylene carbonate (EVC); fluorinated cyclic carbonates such as fluoroethylene carbonate and trifluoropropylene carbonate; and chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethylmethyl carbonate (EMC).

[0042] The nitrile compounds include mononitrile compounds and dinitrile compounds.

[0043] Examples of mononitrile compounds include propionitrile, butyronitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, pelargononitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, and 2-hexenenitrile.

[0044] Dinitrile compounds include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, and 2,3-dimethylsuccinonitrile. Nitrile, 2,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2,2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl- 2,3-Dimethylsuccinonitrile, 2,2-Diisobutyl-3,3-dimethylsuccinonitrile, 2-Methylglutaronitrile, 2,3-Dimethylglutaronitrile, 2,4-Dimethylglutaronitrile, 2,2,3,3-Tetramethylglutaronitrile, 2,2,4,4-Tetramethylglutaronitrile, 2,2,3,4-Tetramethylglutaronitrile, 2,3,3,4-Tetramethylglutaronitrile, Maleonitrile, Fumaronitrile, 1, Examples include 4-dicyanopentane, 2,6-dicyanoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedithio)dipropionitrile, and 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane.

[0045] Among the nitrile compounds, dinitrile compounds are preferred, and compounds represented by the following formula (2) are more preferred. NC-R 3 -CN (2) (R 3 represents an alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 10 carbon atoms.

[0046] R in Equation (2) 3 is preferably an alkylene group having 1 to 6 carbon atoms. Examples of the alkylene group having 1 to 6 carbon atoms include methylene, ethylene, n-propylene, isopropylene, n-butylene, t-butylene, n-pentylene, isopentylene, and n-hexylene.

[0047] Among the dinitrile compounds, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile and suberonitrile are preferred, and malononitrile, succinonitrile, glutaronitrile and adiponitrile are more preferred.

[0048] Examples of sulfonyl compounds include sulfones such as dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, and tert-butyl methyl sulfone, sulfolanes such as sulfolane (tetramethylene sulfone), 2-methyl sulfolane, 3-methyl sulfolane, and 2,4-dimethyl sulfolane, sultones such as sultone, 1,3-propane sultone, and 1,4-butane sultone, busulfan, and sulfolene. Among sulfonyl compounds, sulfones and sulfolanes are preferred, and of these, dimethyl sulfone and sulfolane are more preferred, with sulfolane being even more preferred.

[0049] Examples of carboxylic acid anhydrides include succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, and phenylsuccinic anhydride.

[0050] Examples of the sulfate compound include methyl methanesulfonate and trimethylene glycol sulfate.

[0051] The thioether compound may, for example, be tetramethylthiuram monosulfide.

[0052] Examples of sulfite compounds include ethylene sulfite.

[0053] Examples of the nitrogen-containing cyclic compound include 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, N-methylsuccinimide, etc. These nitrogen-containing cyclic compounds may be used alone or in combination of two or more.

[0054] The content of the salt dissociating agent (total content when two or more types are used in combination) is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, even more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of the components constituting the electrolyte composition of the present invention (100% by mass), from the viewpoint of further promoting dissociation of the alkali metal salt into ions and further improving the ionic conductivity of the composition. The content of the salt dissociating agent is particularly preferably 10% by mass or more and 40% by mass or less, based on the total amount of the components constituting the electrolyte composition of the present embodiment (100% by mass).

[0055] The electrolyte composition of the present embodiment may also contain components other than the fluorine-based polymer, the photo- and / or thermosetting monomer, the alkali metal salt, and the salt dissociator (polymerization initiator, solvent, additive, and other components).

[0056] <Polymerization initiator> The electrolyte composition of the present embodiment may contain a polymerization initiator.

[0057] Examples of polymerization initiators include photoradical polymerization initiators, thermal radical initiators, anionic polymerization initiators, photoanionic polymerization initiators, and epoxy resin curing agents. Here, photoradical polymerization initiators generate polymerization-initiating radicals upon irradiation with active energy rays, and thermal radical polymerization initiators generate polymerization-initiating radicals upon heating. Furthermore, photoanionic polymerization initiators generate polymerization-initiating anion species upon irradiation with active energy rays, thereby initiating a polymerization reaction. Furthermore, epoxy resin curing agents are used as curing agents when curing epoxy resins, and are capable of initiating a ring-opening polymerization reaction of epoxy groups. The anionic polymerization initiator referred to here is a component that initiates a polymerization reaction by generating polymerization-initiating anion species, but does not fall under the category of photoanionic polymerization initiators.

[0058] The photoradical polymerization initiator is not particularly limited, but examples thereof include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl acetophenones such as 1-[4-(1-methylvinyl)phenyl]propanone oligomer, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, and 2-dimethylamino-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholyl)phenyl]-1-butanone; Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxylcarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, (4-benzoylbenzyl)trimethylammonium chloride and other benzophenones, benzoin, benzoin methyl ether benzoins such as benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; thioxanthones such as 2-isopropyl thioxanthone, 4-isopropyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and bis(2,4,Examples of suitable photo-radical polymerization initiators include acylphosphine oxides such as 6-trimethylbenzoyl)phenylphosphine oxide, titanocenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium, oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), and oxyphenylacetic acid esters such as oxyphenylacetic acid, 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid, 2-(2-hydroxyethoxy)ethyl ester. These photo-radical polymerization initiators may be used alone or in combination of two or more. Of these photoradical polymerization initiators, acetophenones, benzophenones, and acylphosphine oxides are preferred, and 1-hydroxycyclohexyl phenyl ketone, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are particularly preferred.

[0059] The thermal radical polymerization initiator is not particularly limited, but examples thereof include methyl ethyl ketone peroxide, cyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetacetate peroxide, acetyl acetate peroxide, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-cyclohexane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)-2-methyl cyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, 1,1-bis(t-butylperoxy)butane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, t-butyl hydroperoxide, α,α'-bis(t- (butylperoxy)diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluoyl peroxide, benzoyl peroxide , di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethoxyhexyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-s-butyl peroxydicarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate, α,α'-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate, 1,1,3,3-Tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxy t-butylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxyisobutyrate, t-butylperoxymalate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-butylperoxyacetate, t-butylperoxy-m-toluylbenzoate, t-butylperoxy Organic peroxide initiators such as dibenzoate, bis(t-butylperoxy)isophthalate, 2,5-dimethyl-2,5-bis(m-toluylperoxy)hexane, t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, t-butylperoxyallyl monocarbonate, t-butyltrimethylsilyl peroxide, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 2,3-dimethyl-2,3-diphenylbutane, 2-phenylazo-4-methoxy-2,4-diphenylpropanol, Methylvaleronitrile, 1-[(1-cyano-1-methylethyl)azo]formamide, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2'-Azobis[N-(4-chlorophenyl)-2-methylpropionamidine)]dihydrochloride, 2,2'-Azobis[N-(4-hydrophenyl)-2-methylpropionamidine)]dihydrochloride, 2,2'-Azobis[2-methyl-N-(phenylmethyl)propionamidine]dihydrochloride, 2,2'-Azobis[2-methyl-N-(2-propenyl)propionamidine]dihydrochloride, 2,2'-Azobis[N-(2-hydroxyethyl)-2 -methylpropionamidine)] dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane) dihydrochloride, 2,2'-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane) Dihydrochloride, 2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl)propane] dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide} , 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropionamide), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanopentanoic acid), 2,Azo initiators such as 2'-azobis[2-(hydroxymethyl)propionitrile], acetophenones such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer, benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, benzophenone, o- Examples of suitable thermal radical polymerization initiators include benzophenones such as methyl benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(t-butylperoxylcarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide, and (4-benzoylbenzyl)trimethylammonium chloride, as well as thioxanthones such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride. These thermal radical polymerization initiators may be used alone or in combination of two or more. Of these thermal radical polymerization initiators, organic peroxide initiators and azo initiators are preferred.

[0060] The anionic polymerization initiator is not particularly limited, but examples thereof include alkali metal compounds having an alkali metal and a carbon anion, such as sodium naphthalene, n-butyllithium, and t-butyllithium; trialkylaluminums, such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, tributylaluminum, and triisobutylaluminum; chlorodialkylaluminum, chlorodiethylaluminum, chlorodipropylaluminum, chlorodiisopropylaluminum, chlorodibutylaluminum, chlorodiisobutylaluminum, bispentamethylcyclopentadienyl samarium, and methyl-bispentamethylcyclopentadienyl samarium.

[0061] The photoanionic polymerization initiator is not particularly limited, but examples thereof include alkoxytitanium, p-chlorophenyl-o-nitrobenzyl ether, and the like.

[0062] These anionic polymerization initiators and photoanionic polymerization initiators may be used either alone or in combination of two or more.

[0063] The epoxy resin curing agent is not particularly limited, but examples thereof include chain aliphatic polyamines such as diethylenetriamine, triethylenetetramine, and dipropolediamine; cyclic aliphatic polyamines such as N-aminoethylpiperazine, menthenediamine, and isophoronediamine; aromatic amines such as metaphenylenediamine and diaminodiphenylmethane; tertiary amines such as 1,8-diazabicyclo(5,4,0)-undecene-7, 1,5-diazabicyclo(4,3,0)-nonene-5, and tris(dimethylaminomethyl)phenol; 1-cyanoethyl-2-ethyl-4-methyl-4-methyl-2-propanediamine; Examples of epoxy resin curing agents include imidazoles such as imidazole and 2-ethyl-4-methylimidazole, acid anhydrides such as ethylene glycol bistrimellitate, tetrahydrophthalic anhydride, succinic anhydride, methylcyclohexene dicarboxylic anhydride, chlorendic anhydride, polyazelaic anhydride, and 4-methylhexahydrophthalic anhydride, photocationic polymerization initiators such as diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate, dicyandiamide, triphenylphosphine, and tetraphenylphosphonium tetraphenylborate. These epoxy resin curing agents may be used alone or in combination of two or more.

[0064] From the viewpoint of film-forming properties, the content of the polymerization initiator (total content when two or more types are used in combination) relative to the amount of monomers has a lower limit of preferably 0.1 mass % or more, more preferably 0.2 mass % or more, and even more preferably 0.5 mass % or more, and an upper limit of preferably 20 mass % or less, more preferably 15 mass % or less, and even more preferably 10 mass % or less.

[0065] <Solvents, additives, and other ingredients> The electrolyte composition of this embodiment may contain a solvent as needed. The solvent preferably has a boiling point lower than that of the salt dissociating agent.

[0066] The solvent is not particularly limited as long as it has a boiling point lower than that of the salt dissociating agent, but it is preferable that the solvent dissolves the composition uniformly.

[0067] Specific examples of the solvent include acetonitrile, dimethyl carbonate, ethyl methyl carbonate, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, tetrahydrofuran, acetone, ethanol, ethyl acetate, and water. These solvents may be used in combination. The amount of the solvent used is not particularly limited and may be determined appropriately depending on the production method and materials used.

[0068] The difference in boiling point between the solvent and the salt dissociating agent is preferably at least 50° C., more preferably at least 80° C., and most preferably at least 100° C. When the difference in boiling point is within the above-mentioned preferred range, the salt dissociating agent can be sufficiently prevented from decreasing when the solvent is dried, and the effects of the present invention can be more fully exhibited.

[0069] The boiling point of the solvent is preferably 150°C or lower, more preferably 120°C or lower.

[0070] From the viewpoint of film-forming properties, the upper limit of the content of the solvent (total content when two or more types are used in combination) relative to the entire electrolyte composition (100% by mass of the total amount of the components constituting the electrolyte composition of the present invention) is preferably 18% by mass or less, more preferably 15% by mass or less, even more preferably 12% by mass or less, and particularly preferably 10% by mass or less, and the lower limit is 0% by mass or more.

[0071] The electrolyte composition of this embodiment may contain, as necessary, additives for improving various characteristics of secondary batteries, such as non-fluorinated polymers such as polyether polymers, (meth)acrylic polymers, nitrile polymers, and diene polymers, emulsifiers such as anionic emulsifiers, nonionic emulsifiers, and cationic emulsifiers, thickeners such as styrene-maleic acid copolymers and alkali-soluble (meth)acrylic acid-(meth)acrylic acid ester copolymers, preservatives, etc. The content of the additives in the non-volatile content of the electrolyte composition is preferably 0 to 15% by mass, more preferably 0 to 10% by mass.

[0072] The electrolyte composition of this embodiment may contain other components as described below, provided that the purpose of the present invention is not impaired. Examples of other components include saturated hydrocarbon compounds such as heptane, octane, and cycloheptane; polymerization inhibitors used in the production of polymers; chain transfer agents and unreacted reactants; by-products formed by decomposition of the reactants; and binders other than modified cellulose. Examples of other binders include synthetic rubbers such as styrene-butadiene rubber and nitrile-butadiene rubber; polyamide resins such as polyamideimide; polyolefin resins such as polyethylene and polypropylene; poly(meth)acrylic resins; polyacrylic acid; and cellulose resins such as carboxymethyl cellulose (excluding modified cellulose). Each of the other components may be used alone, or two or more of them may be used in combination.

[0073] The content of other components (total content when two or more types are used in combination) relative to the entire electrolyte composition (100% by mass of the total amount of components constituting the electrolyte composition of the present invention) is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less, and the lower limit is 0% by mass or more, particularly from the viewpoint of not inhibiting lithium ion conductivity.

[0074] As described above, the electrolyte composition of this embodiment is composed of components such as a fluorine-based polymer, a photo- and / or thermosetting monomer, an alkali metal salt, a salt dissociating agent, and optionally other components, and can be prepared, for example, by mixing these components in predetermined amounts. The electrolyte composition can be suitably used as various battery materials (electrode composition, electrolyte composition) such as electrodes and electrolyte membranes.

[0075] The following describes a cured electrolyte product obtained by curing the electrolyte composition of the present embodiment, an electrode formed using the electrolyte composition, and a secondary battery formed using the cured electrolyte product and / or an electrode.

[0076] <Cured electrolyte> The cured electrolyte obtained by curing the electrolyte composition of this embodiment has a lithium ion conductivity of 2.1 × 10 -4 (S / cm) or more, and more preferably 2.5×10 -4 (S / cm) or more, more preferably 3.0 × 10 -4 (S / cm) or more.

[0077] The electrolyte cured product obtained by curing the electrolyte composition of this embodiment has an ionic conductivity of 3.0 × 10 -4 (S / cm) or more, and more preferably 4.0×10 -4 (S / cm) or more, more preferably 5.0 × 10 -4 (S / cm) or more.

[0078] The cured electrolyte obtained by curing the electrolyte composition of this embodiment preferably has a lithium transference number of 0.24 or more, more preferably 0.4 or more, and even more preferably 0.5 or more.

[0079] The cured electrolyte obtained by curing the electrolyte composition of the present embodiment is suitable for use as a solid electrolyte.

[0080] The thickness of the cured electrolyte film is preferably 5 μm to 300 μm, more preferably 10 μm to 250 μm, and even more preferably 15 μm to 200 μm.

[0081] The cured electrolyte product may contain a solvent, but the solvent is preferably removed by drying before or after the formation of the cured product. The upper limit of the solvent content in the cured electrolyte product is preferably 18% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 1% by mass or less, and the lower limit is 0% by mass or more. Note that a solvent may be used when curing the electrolyte composition of this embodiment to obtain the cured electrolyte product, but it is also preferable from the viewpoints of safety and the environment to obtain the cured electrolyte product without using a solvent.

[0082] The electrolyte composition of the present embodiment has excellent film-forming properties, and therefore, an electrolyte membrane can be formed without using a support (separator), that is, a free-standing membrane can be formed.

[0083] The cured electrolyte of the present embodiment is preferably a free-standing membrane that does not include a support, but may include a support.

[0084] The support (separator) is not particularly limited, but examples thereof include woven fabric, nonwoven fabric, (micro)porous membrane, and glass molded body.

[0085] Examples of the woven fabric and nonwoven fabric include those made of polyolefin resins such as polypropylene, polyethylene, and polymethylpentene, polyester resins such as polyethylene terephthalate (PET), polyamide resins such as nylon, aramid resins such as polyparaphenylene terephthalamide, acrylic resins, polyvinyl alcohol resins, cellulose resins (cellulose fibers), alumina fibers, ceramic fibers, glass fibers, and the like.

[0086] Examples of the (micro)porous membrane include those made of polyolefin resins such as polypropylene, polyethylene, and ethylene-propylene copolymers, polyester resins, fluororesins such as tetrafluoroethylene-perfluoroalkoxyethylene copolymers, polyether ether ketone, polybutylene terephthalate, polyphenylene sulfide, polyamide resins, and polyimides.

[0087] The glass molded body may be, for example, a glass cloth.

[0088] In order to further improve hydrophilicity, these separators may be hydrophilized by adding a surfactant, sulfonating with chemicals such as fuming sulfuric acid or chlorosulfonic acid, fluorinating, or grafting, or by corona discharge or plasma discharge.

[0089] The separator is preferably made of at least one material selected from the group consisting of a cellulose nonwoven fabric, a PET nonwoven fabric, a glass nonwoven fabric, a polyolefin nonwoven fabric, a polyolefin microporous membrane, and a polyimide porous membrane, and more preferably a cellulose nonwoven fabric or a polyolefin microporous membrane.

[0090] The electrolyte cured product of this embodiment can be obtained by curing the electrolyte composition of this embodiment.The method for producing the electrolyte cured product of the present invention can be, for example, the method of mixing the electrolyte composition, forming the obtained mixture into a sheet, and then curing; the method of applying the electrolyte composition by doctor blade method or immersing a support in the electrolyte composition, and then drying as necessary, and then curing; the method of kneading and molding the electrolyte composition into a sheet, and then drying as necessary, and then bonding to a support via a conductive adhesive, and then pressing and curing; the method of applying or casting the composition to which a liquid lubricant is added onto a current collector, forming it into a desired shape, and then removing the liquid lubricant, and then stretching in a uniaxial or multiaxial direction.

[0091] <Electrode> The electrolyte composition of the present embodiment can be suitably used as a material for electrodes for batteries. An electrode formed using the electrolyte composition of the present embodiment also constitutes the present invention. The electrolyte composition of the present invention may be used for either a positive electrode or a negative electrode.

[0092] The cured electrolyte material of the present embodiment can be suitably used as an electrode for a battery. The electrode of the present embodiment is preferably obtained by curing a composition containing the electrolyte composition of the present embodiment. The cured electrolyte material of the present embodiment may be used for either a positive electrode or a negative electrode.

[0093] The positive electrode is a positive electrode current collector supported by a positive electrode active material composition containing, in addition to the electrolyte composition of this embodiment, other electrolytes, a positive electrode active material, a conductive additive, a binder, a dispersion solvent, etc., and is usually formed into a sheet shape. As the other electrolytes, known polymer solid electrolytes, inorganic solid electrolytes, molten salts, etc. can be used in combination.

[0094] Examples of the method for manufacturing the positive electrode include, for example, a method in which a positive electrode active material composition is mixed, the obtained mixture is formed into a sheet shape and then cured; a method in which the positive electrode active material composition is applied to the positive electrode current collector by a doctor blade method or the like, or the positive electrode current collector is immersed in the positive electrode active material composition and then dried as necessary; a method in which a sheet obtained by kneading and forming the positive electrode active material composition is dried as necessary and then joined to the positive electrode current collector via a conductive adhesive and pressed and dried; a method in which a positive electrode active material composition added with a liquid lubricant is applied or cast on the positive electrode current collector, formed into a desired shape, then the liquid lubricant or the like is removed, and then stretched in a uniaxial or multi-axial direction, and the like.

[0095] The material of the positive electrode current collector is not particularly limited, and for example, conductive metals such as aluminum, aluminum alloy, SUS (stainless steel), and titanium can be used. Among them, aluminum is preferable from the viewpoint of being easy to process into a thin film and being inexpensive.

[0096] The positive electrode active material only needs to be capable of occluding and releasing ions, and conventionally known positive electrode active materials are used. Specifically, transition metal oxides such as ternary oxides represented by MCoO2, MNiO2, MMnO2, MNi 1-x-y Co x Mn y O2 or MNi 1-x-y Co x Al y O2 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), nickel manganate represented by M x Ni y Mn (2-y) O4 (0.9 ≤ x ≤ 1.1, 0 < y < 1), compounds having an olivine structure such as MAPO4 (A = Fe, Mn, Ni, Co), solid solution materials incorporating a plurality of transition metals (a solid solution of electrochemically inert layered M2MnO3 and electrochemically active layered MM”O ([M” = transition metals such as Co, Ni])(M represents an alkali metal ion)) and the like can be exemplified as the positive electrode active material. These positive electrode active materials may be used alone or in combination of a plurality.

[0097] Examples of the conductive additive include acetylene black, carbon black, graphite, metal powder materials, single-walled carbon nanotubes, multi-walled carbon nanotubes, and vapor-grown carbon fibers.

[0098] Examples of binders include synthetic rubbers such as styrene-butadiene rubber and nitrile-butadiene rubber, polyamide resins such as polyamideimide, polyolefin resins such as polyethylene and polypropylene, and cellulose resins such as poly(meth)acrylic resins, polyacrylic acid, and carboxymethyl cellulose. These binders may be used alone or in combination. These binders may be dissolved in a solvent or dispersed in a solvent when used.

[0099] The amounts of the conductive additive and binder to be blended can be adjusted as appropriate in consideration of the intended use of the battery (emphasis on output, emphasis on energy, etc.), ion conductivity, and the like.

[0100] When producing a positive electrode, examples of solvents used in the positive electrode active material composition include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, tetrahydrofuran, acetonitrile, acetone, ethanol, ethyl acetate, and water. These solvents may be used in combination. The amount of solvent used is not particularly limited and may be determined appropriately depending on the production method and materials used.

[0101] The negative electrode active material may be any conventionally known negative electrode active material used in batteries, as long as it is capable of absorbing and releasing ions. Specifically, examples of the negative electrode active material include alkali metals, metal alloys such as alkali metal-aluminum alloys, graphite materials such as artificial graphite and natural graphite, mesophase sintered bodies made from coal or petroleum pitch, carbon materials such as non-graphitizable carbon, Si-based negative electrode materials such as Si, Si alloys, and SiO, and Sn-based negative electrode materials such as Sn alloys.

[0102] The negative electrode can be manufactured by the same method as the positive electrode, and the conductive additive, binder, and material dispersion solvent used in manufacturing the negative electrode are also the same as those used in manufacturing the positive electrode.

[0103] <Secondary battery> The secondary battery of this embodiment is constructed using the electrolyte cured material of this embodiment and / or the electrode of this embodiment.

[0104] The secondary battery of this embodiment preferably includes the above-described cured electrolyte material of this embodiment and / or the above-described electrode of this embodiment. The secondary battery of this embodiment is preferably a secondary battery including a positive electrode and a negative electrode, with the cured electrolyte material provided between the positive electrode and the negative electrode, and is preferably housed in an exterior case together with the positive electrode, the negative electrode, etc.

[0105] The shape of the secondary battery of this embodiment is not particularly limited, and any of the conventionally known shapes of batteries can be used, such as cylindrical, prismatic, laminated, coin, large, etc. Furthermore, when the secondary battery of this embodiment is used as a high-voltage power source (several tens of volts to several hundreds of volts) to be mounted on an electric vehicle, a hybrid electric vehicle, etc., it can also be made into a battery module consisting of individual batteries connected in series.

[0106] In one preferred embodiment of the present invention, the cured electrolyte product or electrode containing the electrolyte composition of the present embodiment is a cured electrolyte product or electrode for a secondary battery.

[0107] In one preferred embodiment of the present invention, the secondary battery is a lithium ion secondary battery.

[0108] Example The present disclosure will be described below based on examples. Note that the present disclosure is not limited to the following examples, and the following examples can be modified or changed based on the spirit of the present disclosure, and such modifications are not excluded from the scope of the present disclosure.

[0109] ~Preparation of electrolyte composition and preparation of hardened electrolyte~ Example 1 First, as shown in Table 1 below, 0.69 g (23 parts by mass) of lithium bis(fluorosulfonyl)imide (LiFSI, manufactured by Nippon Shokubai Co., Ltd.), 1.56 g (52 parts by mass) of sulfolane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 0.6 g (20 parts by mass) of PVDF-HFP (KYNER FLEX 2801-00, manufactured by ARKEMA Corporation), 0.15 g (5 parts by mass) of trifunctional urethane acrylate (UA7100, manufactured by Shin-Nakamura Chemical Co., Ltd.), 0.015 g (0.5 parts by mass) of a polymerization initiator (Omirad754, manufactured by IGM Resins BV), and 3.0 g of acetone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed into a PP (polypropylene) container (100 mL) and mixed at 2000 rpm for 3 minutes to prepare an electrolyte composition.

[0110] The prepared electrolyte solution was then applied to a Teflon sheet, the acetone solvent was removed by vacuum drying, and the solution was then heated under the light of an ultra-high pressure mercury lamp (4.2 mW / cm 2 The film was irradiated with UV (ultraviolet) light (365 nm after passing through a Teflon (registered trademark) sheet) for 12 minutes to carry out a photopolymerization reaction, thereby producing a cured electrolyte film with a thickness of 200 μm.

[0111] <Example 2> As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was prepared by the same procedure as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 10 parts by mass and the amount of sulfolane was changed from 52 parts by mass to 65 parts by mass.

[0112] Example 3 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 10 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 17.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 65 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.75 parts by mass.

[0113] Example 4 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 12 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 28 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 53 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.7 parts by mass.

[0114] <Example 5> As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 12 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 24.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 10.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 53 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 1.05 parts by mass.

[0115] Example 6 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 26 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 12 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 3 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 59 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.3 parts by mass.

[0116] Example 7 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 26 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 10.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 4.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 59 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.45 parts by mass.

[0117] Example 8 As shown in Table 1, the same procedure as in Example 1 was carried out except that the amount of PVDF-HFP was changed from 20 parts by mass to 23.75 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 1.25 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.125 parts by mass, to prepare a cured electrolyte having a thickness of 200 μm.

[0118] Example 9 As shown in Table 1, the same procedure as in Example 1 was carried out except that the amount of PVDF-HFP was changed from 20 parts by mass to 17.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7.5 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.75 parts by mass, to prepare a cured electrolyte material having a thickness of 200 μm.

[0119] Example 10 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 26 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 28 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 39 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.7 parts by mass.

[0120] Example 11 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 26 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 24.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 10.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 39 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 1.05 parts by mass.

[0121] Example 12 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was prepared by the same procedure as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 32 parts by mass and the amount of sulfolane was changed from 52 parts by mass to 43 parts by mass.

[0122] Example 13 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 26 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 17.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 43 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.75 parts by mass.

[0123] Example 14 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 35 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 28 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 7 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 30 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 0.7 parts by mass.

[0124] Example 15 As shown in Table 1, a cured electrolyte material having a thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 35 parts by mass, the amount of PVDF-HFP was changed from 20 parts by mass to 24.5 parts by mass, the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 10.5 parts by mass, the amount of sulfolane was changed from 52 parts by mass to 30 parts by mass, and the amount of polymerization initiator was changed from 0.5 parts by mass to 1.05 parts by mass.

[0125] Example 16 As shown in Table 2 below, a cured electrolyte material with a film thickness of 200 μm was produced in the same manner as in Example 1, except that the amount of LiFSI blended was changed from 23 parts by mass to 25 parts by mass and 50 parts by mass of EC / EMC was used instead of 52 parts by mass of sulfolane. Here, EC / EMC is a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7.

[0126] Example 17 As shown in Table 2, a cured electrolyte material with a film thickness of 200 μm was prepared by the same procedure as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 22 parts by mass and 53 parts by mass of EC was used instead of 52 parts by mass of sulfolane.

[0127] Example 18 As shown in Table 2, a cured electrolyte material having a thickness of 200 μm was prepared by the same procedure as in Example 1, except that the amount of LiFSI was changed from 23 parts by mass to 34 parts by mass and 41 parts by mass of SN (succinonitrile) was used instead of 52 parts by mass of sulfolane.

[0128] Example 19 As shown in Table 2, a cured electrolyte material having a film thickness of 200 μm was produced in the same manner as in Example 1, except that 20 parts by mass of PVDF-HFP (manufactured by ARKEMA Corporation) was used instead of KYNER FLEX2801-00.

[0129] Example 20 As shown in Table 2, a cured electrolyte material having a thickness of 200 μm was prepared in the same manner as in Example 1, except that 30 parts by mass of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was used instead of 23 parts by mass of LiFSI and the amount of sulfolane was changed from 52 parts by mass to 45 parts by mass.

[0130] <Example 21> As shown in Table 2, a cured electrolyte material having a film thickness of 200 μm was prepared in the same manner as in Example 1, except that 5 parts by mass of the trifunctional urethane acrylate was replaced with a bifunctional PEO (polyethylene oxide)-terminated acrylate (409073 manufactured by Aldrich).

[0131] <Example 22> As shown in Table 2, a cured electrolyte material having a film thickness of 200 μm was prepared in the same manner as in Example 1, except that 5 parts by mass of the trifunctional urethane acrylate was replaced with a trifunctional PEO-terminated acrylate (455008 manufactured by Aldrich).

[0132] <Comparative Example 1> As shown in Table 2, a cured electrolyte material having a thickness of 200 μm was prepared in the same manner as in Example 1, except that the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 0 parts by mass and the amount of PVDF-HFP was changed from 20 parts by mass to 25 parts by mass.

[0133] <Comparative Example 2> As shown in Table 2, a cured electrolyte material having a thickness of 200 μm was prepared in the same manner as in Example 1, except that the amount of PVDF-HFP was changed from 20 parts by mass to 0 parts by mass and the amount of trifunctional urethane acrylate was changed from 5 parts by mass to 25 parts by mass.

[0134] ~Physical property evaluation~ The ionic conductivity, lithium transport number, lithium ion conductivity, and number of cycles of current test were measured for the cured electrolyte materials produced in each of the experimental examples of Examples 1 to 22 and Comparative Examples 1 and 2. Table 1 shows the experimental results of each of the experimental examples of Examples 1 to 15, and Table 2 shows the experimental results of each of the experimental examples of Examples 16 to 22 and Comparative Examples 1 and 2.

[0135] [Table 1]

[0136] [Table 2]

[0137] ~Conductivity measurement~ A symmetrical cell was produced by sandwiching a φ16 mm punched out piece of the electrolyte cured material produced in each of the experimental examples of Examples 1 to 22 and Comparative Examples 1 and 2 described above between two sheets of lithium foil (thickness 0.2 mm, manufactured by Honjo Metals Co., Ltd.) punched out to φ13 mm, and using a positive electrode case, negative electrode cap, 1.0 mm thick SUS spacer, wave washer, and gasket from CR2032 type coin cell components (manufactured by Hosen Co., Ltd.), the positive electrode case, negative electrode cap, 1.0 mm thick SUS spacer, wave washer, and gasket, and crimping them together using an automatic coin crimping machine (manufactured by Hosen Co., Ltd.).

[0138] Impedance analysis of the symmetrical cell was performed using a potentiogalvanostat (VSP-300, Biologic) under conditions of 1 MHz to 10 mHz and an amplitude of 10 mV. The bulk resistance component obtained from the Cole-Cole plot was defined as Rb, and the interface resistance component between the lithium foil and the hardened electrolyte was defined as RSi (Ω).

[0139] Next, a 20 mV application test was carried out for 5 minutes, and the current value immediately after the voltage application and the current value 5 minutes later were defined as Ii (A) and Ic (A), respectively. With 20 mV applied, impedance analysis was carried out under conditions of 1 MHz to 10 mHz and an amplitude of 10 mV, and the interfacial resistance component between the lithium foil and the cured electrolyte obtained from the Cole-Cole plot was defined as RSc (Ω). Here, the thickness of the measurement specimen was defined as T (cm), and the area of ​​contact between the cured electrolyte and the lithium foil was defined as the area of ​​the measurement specimen, A (cm). 2 ) and the ionic conductivity σ (S / cm) was calculated based on the following formula (α). σ=T / A / Rb(α) The lithium transference number was calculated based on the following formula (β) when the applied voltage was E (V). tLi=Ic(E-RSiIi) / Ii(E-RScIc) (β) The lithium ion conductivity σLi was calculated based on the following formula (γ) using the above ionic conductivity and lithium transference number. σ Li =σ×tLi (γ)

[0140] ~Electrical Test~ The symmetric cell prepared for conductivity measurement was subjected to a current test using a charge-discharge tester (ACD-01 manufactured by Asuka Electronics Co., Ltd.). In this test, I = ±0.265 mA (±0.2 mA / cm 2 ) pulse current every 2 hours (0.4mAh / cm 2 ) and current was passed through. If the cured electrolyte material was not short-circuited, the resistance value derived from the lithium ion conductivity of the cured electrolyte material was obtained. If a short circuit occurred in the cured electrolyte material due to the growth of lithium metal dendrites, the resistance value dropped sharply. Therefore, the number of pulse current cycles until a short circuit occurred was used to evaluate the dendrite resistance performance.

[0141] As can be seen from the experimental results by comparing Examples 1 to 15 with Comparative Examples 1 and 2, in Examples 1 to 15, which contained both a fluoropolymer and a curable monomer and in which the total amount of the fluoropolymer and the curable monomer was 10 mass% or more relative to the total amount of the fluoropolymer, the curable monomer, the lithium salt, and the salt dissociator, the number of cycles in the current test exceeded 110, demonstrating improved dendrite resistance. In contrast, in Comparative Examples 1 and 2, which contained only one of a fluoropolymer and a curable monomer, the number of cycles in the current test was less than 110, even though the total amount of the fluoropolymer and the monomer was 25 mass% relative to the total amount of the fluoropolymer, the curable monomer, the lithium salt, and the salt dissociator, demonstrating that the desired dendrite resistance could not be obtained.

[0142] Furthermore, even in Examples 16 to 18 in which the type of salt dissociating agent was changed from sulfolane to ethylene carbonate or the like, the number of cycles in the current test exceeded 130, demonstrating improved dendrite resistance.

[0143] Furthermore, even in Example 19, in which the type of fluorine-based polymer was changed, the number of cycles in the current test exceeded 220, indicating that the dendrite resistance performance was improved.

[0144] Furthermore, even in Example 20, in which the type of lithium salt was changed, the number of cycles in the current test exceeded 230, demonstrating improved dendrite resistance.

[0145] Furthermore, even in Examples 21 and 22 in which the type of curable monomer was changed, the number of cycles in the current test exceeded 160, indicating that the dendrite resistance was improved.

[0146] As described above, the electrolyte composition of this embodiment contains a fluoropolymer and a photo- and / or thermo-curable (or photo- and / or thermo-curable) monomer. The total amount of the fluoropolymer and the curable monomer is 10% by mass or more relative to the total amount of the fluoropolymer, the curable monomer, the alkali metal salt, and the salt dissociator. Therefore, the cured electrolyte obtained by curing the electrolyte composition has a double network structure in which the cured product of the photo- and / or thermo-curable monomer and the fluoropolymer are entangled. This makes the cured electrolyte harder than when the fluoropolymer is not added, thereby improving the film strength of the cured electrolyte as much as possible while maintaining high lithium ion conductivity. Furthermore, the improved film strength of the cured electrolyte obtained by curing the electrolyte composition inhibits the growth of alkali metal dendrites, such as lithium, in the cured electrolyte, thereby preventing short circuits due to the growth of such dendrites. [Industrial Applicability]

[0147] As described above, the present invention is useful for electrolytes used in secondary batteries.

Claims

1. a fluorine-based polymer; a photo- and / or thermosetting monomer; an alkali metal salt; and a salt dissociating agent, the total amount of the fluoropolymer and the monomer is 15% by mass or more and 35% by mass or less based on the total amount of the fluoropolymer, the monomer, the alkali metal salt, and the salt dissociating agent; The electrolyte composition is characterized in that the content of the fluoropolymer is 70% by mass or more and 95% by mass or less based on the total amount of the fluoropolymer and the monomer.

2. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the alkali metal salt contains a lithium salt represented by the following formula (1): LiN(SO ２ R １ )(SO ２ R ２ ) (1) (R １ and R ２ represents a fluorine atom or a fluoroalkyl group having 1 to 3 carbon atoms.

3. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the fluorine-based polymer contains vinylidene fluoride as a constituent unit.

4. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the monomer contains a urethane bond as a constituent unit.

5. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the salt dissociating agent contains at least one of a sulfonyl compound, a carbonate compound, and a nitrile compound.

6. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the salt dissociating agent contains a sulfonyl compound.

7. 10. The electrolyte composition according to claim 1, which is used as a raw material for a solid electrolyte.

8. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the content of the fluorine-based polymer is 3% by mass or more and 50% by mass or less based on the total mass of the electrolyte composition.

9. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the fluorine-based polymer has a weight average molecular weight of 50,000 to 1,000,000.

10. The electrolyte composition according to claim 1, The electrolyte composition is characterized in that the fluorine-based polymer contains a vinylidene fluoride-hexafluoropropylene copolymer.

11. The electrolyte composition according to claim 1, The electrolytic composition is characterized in that the photo- and / or thermosetting monomer has a molecular weight of 50 to 4,000.

12. A cured electrolyte obtained by curing the electrolyte composition according to any one of claims 1 to 11, Lithium ion conductivity is 2.1 x 10 -4 (S / cm) or more.

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