Solid or gel-like electrolyte, curable composition, and power-storage device

Abstract

The present invention provides a solid or gel-like electrolyte that exhibits high ionic conductivity at room temperature.　This solid or gel-like electrolyte contains component (A) and component (B). The molar concentration of the component (B) with respect to 1 kg of the electrolyte is 2.8 mol / kg or more. Component (A): A vinyl polymer which has a structural unit derived from a vinyl monomer including an ester group, and in which the proportion of ester groups calculated by formula (1) is 32 mass% or more. Component (B): An alkali metal salt (however, i=1, 2, …, n each represent a different vinyl monomer. Each w represents the mass ratio of a structural unit derived from a corresponding vinyl monomer in component (A), and w1+w2+… +wn=1 is true.)

Description

Solid or gel electrolyte, curable composition, and electricity storage device

[0001] The present invention relates to a solid or gel electrolyte, a curable composition, and an electricity storage device, and more particularly to a polymer solid electrolyte and a polymer gel electrolyte, and uses thereof.

[0002] Various types of power storage devices have been put to practical use, including secondary batteries such as nickel-metal hydride secondary batteries and lithium-ion secondary batteries, and electric double-layer capacitors. Of these, lithium-ion secondary batteries are used in a wide range of applications due to their high energy density and battery capacity.

[0003] Lithium-ion secondary batteries have a negative electrode, a positive electrode, and an electrolyte, and are charged and discharged by transferring lithium ions between the electrodes via the electrolyte. Organic electrolyte solutions have traditionally been used as the electrolyte. In recent years, however, the use of solid or gel electrolytes instead of organic electrolyte solutions has been proposed as a technique to eliminate concerns about electrolyte leakage and short circuits within the battery due to overcharge and overdischarge (see, for example, Patent Document 1 and Non-Patent Document 1).

[0004] Patent Document 1 discloses a polymer solid electrolyte produced by polymerizing a monomer having a carbonate skeleton that coordinates lithium ions in the presence of an electrolyte salt. Non-Patent Document 1 also discloses a polymer solid electrolyte produced by dissolving a polymer obtained by polymerization using a monomer having a carbonate skeleton and an electrolyte salt in a solvent.

[0005] Japanese Patent Application Publication No. 03-156803

[0006] Macromolecules, 2007, Vol. 40, pp. 7558-7565

[0007] However, the inventors' investigations revealed that the polymer solid electrolytes disclosed in Patent Document 1 and Non-Patent Document 1 did not have sufficient ionic conductivity at room temperature. The ionic conductivity of polymer solid electrolytes and polymer gel electrolytes (hereinafter collectively referred to as "solid or gel electrolytes") tends to be lower than that of, for example, inorganic solid electrolytes, and there is room for further improvement in order to enhance the practical utility of solid or gel electrolytes.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid or gel electrolyte that exhibits high ionic conductivity at room temperature.

[0009] Means for Solving the Problems The present inventors have conducted extensive research to solve the above problems and have found that a vinyl polymer having a specific structure can contain an alkali metal salt at a specific concentration or more, and that a solid or gel electrolyte containing the vinyl polymer and the alkali metal salt has high ionic conductivity even at room temperature, thereby completing the present invention.

[0010] The present invention is as follows: [1] A solid or gel electrolyte containing the following components (A) and (B), wherein the molar concentration of component (B) per 1 kg of electrolyte is 2.8 mol / kg or more: Component (A): a vinyl polymer having a structural unit derived from a vinyl monomer containing an ester group, and having an ester group ratio calculated by formula (1) of 32 mass% or more; and Component (B): an alkali metal salt. (where i = 1, 2, ..., n represents different vinyl monomers; w represents the mass ratio of structural units derived from each vinyl monomer in component (A); w １ +w ２ +...+w ｎ = 1.) [2] The solid or gel electrolyte according to [1], wherein the component (A) is a (meth)acrylic polymer. [3] The solid or gel electrolyte according to [1], wherein the component (A) has a structural unit derived from at least one compound selected from the group consisting of a compound represented by the following general formula [1], a compound represented by the general formula [2], a compound represented by the general formula [3], and a compound represented by the general formula [4]. CH ２ =CR１ -C(=O)O-R 2 [1] (In formula [1], R １ represents a hydrogen atom or a methyl group, R ２ represents a saturated organic group having 1 to 4 carbon atoms. １ and R ２ The total number of carbon atoms is 1 to 4. ２ =CR １ -C(=O)O-(CH ２ ) ２ -O-R ３ [2] (In formula [2], R １ and R ３ represents a hydrogen atom or a methyl group. ２ =CH-OC(=O)-R 4 [3] (In formula [3], R ４ represents a saturated organic group having 1 to 4 carbon atoms.) CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -OC(=O)-R 5 -C(=O)-OH [4] (In formula [4], R １ represents a hydrogen atom or a methyl group, R ５ represents an organic group having 1 to 6 carbon atoms. １ and R ５ The total number of carbon atoms in the (a) and (b) groups is 1 to 6. [4] A curable composition for use in the production of a solid or gel electrolyte, comprising the following components (a) and (B), wherein the molar concentration of component (B) per 1 kg of the curable composition is 2.8 mol / kg or more. Component (a): A vinyl-based monomer component containing a vinyl monomer containing an ester group, wherein the ester group ratio calculated by formula (2) is 32 mass% or more. Component (B): An alkali metal salt (where i = 1, 2, ..., n represents different vinyl monomers; w represents the mass ratio of each vinyl monomer in component (a); w １ +w ２ +...+w ｎ= 1.) [5] The curable composition according to [4], wherein the component (a) contains at least one compound selected from the group consisting of a compound represented by the following general formula [1], a compound represented by the general formula [2], a compound represented by the general formula [3], and a compound represented by the general formula [4]. CH ２ =CR １ -C(=O)O-R 2 [1] (In formula [1], R １ represents a hydrogen atom or a methyl group, R ２ represents a saturated organic group having 1 to 4 carbon atoms. １ and R ２ The total number of carbon atoms is 1 to 4. ２ =CR １ -C(=O)O-(CH ２ ) ２ -O-R ３ [2] (In formula [2], R １ and R ３ represents a hydrogen atom or a methyl group. ２ =CH-OC(=O)-R 4 [3] (In formula [3], R ４ represents a saturated organic group having 1 to 4 carbon atoms.) CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -OC(=O)-R 5 -C(=O)-OH [4] (In formula [4], R １ represents a hydrogen atom or a methyl group, R ５ represents an organic group having 1 to 6 carbon atoms. １ and R ５ The total number of carbon atoms in the groups is 1 to 6. [6] The curable composition according to [4] or [5], wherein the composition is an active energy ray-curable composition. [7] A solid or gel electrolyte that is a cured product of the composition according to any one of [4] to [6]. [8] An electricity storage device comprising the solid or gel electrolyte according to any one of [1] to [3] and [7].

[0011] The solid or gel electrolyte of the present invention can exhibit high ionic conductivity at room temperature, and therefore, by using the solid or gel electrolyte of the present invention as an electrolyte in an electricity storage device such as a lithium ion secondary battery or a capacitor, it is possible to obtain an electricity storage device that achieves both safety and battery performance.

[0012] The present invention will be described in detail below. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0013] <Solid or Gel Electrolyte> The solid or gel electrolyte of the present invention includes a polymer solid electrolyte or a polymer gel electrolyte, and contains the following components (A) and (B): Component (A): a vinyl polymer having structural units derived from a vinyl monomer containing an ester group, and having an ester group ratio calculated by the above formula (1) of 32 mass% or more Component (B): an alkali metal salt In the solid or gel electrolyte of the present disclosure, the molar concentration of component (B) per kg of electrolyte is 2.8 mol / kg or more. Each component contained in the solid or gel electrolyte of the present invention will be described below.

[0014] <Component (A): Vinyl Polymer> The vinyl polymer (hereinafter also referred to as "vinyl polymer (A)") of component (A) has a structural unit derived from a vinyl monomer containing an ester group, and the ester group ratio calculated by the above formula (1) is 32% by mass or more, thereby enabling alkali metal salts to be dissolved at high concentrations and improving ionic conductivity (particularly ionic conductivity at room temperature). This mechanism is presumed to be due to the fact that the solid or gel electrolyte of the present invention is a decoupling system in which the movement of the alkali metal salt is less affected by the mobility of the polymer chain and its diffusion is not inhibited even at high alkali metal salt concentrations. The ester group ratio of the vinyl polymer (A) is preferably 34% by mass or more, more preferably 37% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and even more preferably 50% by mass or more, in order to increase the content of the alkali metal salt (B) in the solid or gel electrolyte and further improve ionic conductivity.

[0015] The vinyl polymer (A) may be any polymer obtained by polymerizing a vinyl monomer component containing a vinyl monomer (hereinafter also referred to as "vinyl monomer M") that contains an ester group and has an ester group ratio of 32% by mass or more as calculated by the above formula (2). The vinyl monomer M is preferably a (meth)acrylic monomer, since structural units derived from the vinyl monomer containing an ester group can be easily introduced into the side chain of the polymer and can be easily produced industrially. In this case, the reaction rate of the monomer can be easily increased, and the polymer obtained in the polymerization reaction can be used as a solid or gel electrolyte without purification. The vinyl polymer (A) is preferably a (meth)acrylic polymer. Of all structural units derived from the monomers constituting the vinyl polymer (A), the proportion of structural units derived from the (meth)acrylic monomer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0016] Furthermore, the proportion of the acrylic monomer among the monomers constituting the vinyl polymer (A) is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 80% by mass or more. When the proportion of the acrylic monomer is within the above range, the glass transition temperature of the vinyl polymer (A) can be sufficiently lowered, which is advantageous in that a solid or gel electrolyte having higher ionic conductivity can be obtained.

[0017] Furthermore, for example, the vinyl monomer M is not particularly limited as long as it contains an ester group and the ester group ratio calculated by the above formula (2) is 32 mass% or more, but it is preferable that it contains at least one compound selected from the group consisting of compounds represented by the following general formula [1], compounds represented by the general formula [2], compounds represented by the general formula [3], and compounds represented by the general formula [4]:

[0018] CH ２ =CR １ -C(=O)O-R 2 [1] (In formula [1], R １ represents a hydrogen atom or a methyl group, R ２ represents a saturated organic group having 1 to 4 carbon atoms. １ and R ２ The total number of carbon atoms is 1 to 4. ２ =CR １ -C(=O)O-(CH ２ ) ２ -O-R ３ [2] (In formula [2], R １ and R ３ represents a hydrogen atom or a methyl group. ２ =CH-OC(=O)-R 4 [3] (In formula [3], R ４ represents a saturated organic group having 1 to 4 carbon atoms.) CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -OC(=O)-R 5 -C(=O)-OH [4] (In formula [4], R １ represents a hydrogen atom or a methyl group, R ５ represents an organic group having 1 to 6 carbon atoms.１ and R ５ The total number of carbon atoms in the formula is 1 to 6. Among these, the compound represented by the general formula [4] is particularly preferred in that it can increase ionic conductivity (particularly ionic conductivity at room temperature).

[0019] Specific examples of the compound represented by the general formula [1] include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl acrylate, isobutyl acrylate, and tert-butyl acrylate. Specific examples of the compound represented by the general formula [2] include 2-methoxyethyl acrylate and 2-hydroxyethyl (meth)acrylate. Specific examples of the compound represented by the general formula [3] include vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl valerate. Specific examples of the compound represented by the general formula [4] include 2-(meth)acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, and 2-acryloyloxyethyl hexahydrophthalic acid. The vinyl monomer M constituting the vinyl polymer (A) may be one type alone or two or more types.

[0020] The compound represented by the general formula [1] is R １ is a hydrogen atom and R ２ is preferably a saturated organic group having 1 or 2 carbon atoms, more preferably methyl acrylate or ethyl acrylate, and even more preferably methyl acrylate. １ is a hydrogen atom and R ３ is a methyl group (2-methoxyethyl acrylate). ４ is a saturated organic group having 1 or 2 carbon atoms, vinyl acetate and vinyl propionate are more preferred, and vinyl acetate is even more preferred. １ is a hydrogen atom or a methyl group and R ５ is an organic group having 2 to 6 carbon atoms, and R １ and R ５The total number of carbon atoms in the group is preferably 2 to 6, more preferably 2-(meth)acryloyloxyethyl-succinic acid or 2-acryloyloxyethyl-phthalic acid, and even more preferably 2-(meth)acryloyloxyethyl-succinic acid.

[0021] The vinyl polymer (A) may be composed solely of structural units derived from the vinyl monomer M, or may further contain structural units derived from a monomer other than the vinyl monomer M that is copolymerizable with the vinyl monomer M (hereinafter also referred to as "other monomer"). However, even if a vinyl monomer is classified as "other monomer," a monomer that contains an ester group and has an ester group ratio calculated by the above formula (2) of 32 mass% or more is classified as the vinyl monomer M. Examples of other monomers include vinyl monomers having a crosslinkable group (hereinafter also referred to as "crosslinkable monomer"). When the vinyl polymer (A) contains structural units derived from a crosslinkable monomer, this is advantageous in that a strong electrolyte membrane can be obtained when a solid or gel electrolyte is formed into a membrane, and that a polymer gel electrolyte can sufficiently retain an electrolytic solution.

[0022] As the crosslinkable monomer, a polyfunctional (meth)acrylate compound having two or more (meth)acryloyl groups can be preferably used. Specific examples of the polyfunctional (meth)acrylate compound include polyol poly(meth)acrylates such as 1,6-hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri- or tetra(meth)acrylate, ditrimethylolpropane tri- or tetra(meth)acrylate, diglycerin tri- or tetra(meth)acrylate, and dipentaerythritol tri-, tetra-, penta-, or hexa(meth)acrylate, as well as oligomers having two or more (meth)acryloyl groups. The crosslinkable monomer constituting the vinyl polymer (A) may be a single type or two or more types.

[0023] The monomers constituting the vinyl polymer (A) may contain compounds other than crosslinkable monomers as other monomers, as long as the effects of the present invention are not impaired. Such compounds may contain ester groups and have an ester group ratio calculated by the above formula (2) of less than 32% by mass. Examples of such compounds include (meth)acrylic acid, (meth)acrylic acid alkyl ester compounds (other than the compounds represented by the above formula [1]), (meth)acrylic acid alicyclic ester compounds, (meth)acrylic acid aromatic ester compounds, (meth)acrylic acid alkoxyalkyl compounds (other than the compounds represented by the above formula [2]), (meth)acrylic acid hydroxyalkyl compounds, and polyalkylene glycol mono(meth)acrylate compounds. As such other monomers, one type may be used alone, or two or more types may be used in combination.

[0024] Of all structural units derived from the monomers constituting the vinyl polymer (A), the proportion of structural units derived from the vinyl monomer M is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of obtaining an electrolyte having excellent ionic conductivity (particularly ionic conductivity at room temperature). In the vinyl polymer (A), there is no particular upper limit on the proportion of structural units derived from the vinyl monomer M. From the viewpoint of sufficiently forming a crosslinked structure, of all structural units derived from the monomers constituting the vinyl polymer (A), the proportion of structural units derived from the vinyl monomer M is, for example, 99% by mass or less, preferably 97% by mass or less.

[0025] The proportion of structural units derived from crosslinkable monomers among all structural units derived from monomers constituting the vinyl polymer (A) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of sufficiently forming a crosslinked structure and imparting toughness when formed into a membrane-like electrolyte. The upper limit of the proportion of structural units derived from crosslinkable monomers in the vinyl polymer (A) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on all structural units derived from monomers constituting the vinyl polymer (A), from the viewpoint of ensuring the flexibility of the electrolyte.

[0026] The range of the proportion of the structural units derived from the crosslinkable monomer to all structural units of the vinyl polymer (A) can be set by appropriately combining the above-mentioned upper and lower limits. Specifically, the range of the proportion of the structural units derived from the crosslinkable monomer to all structural units derived from the monomers constituting the vinyl polymer (A) is preferably 1 to 30 mass%, more preferably 2 to 20 mass%, even more preferably 3 to 20 mass%, and even more preferably 3 to 15 mass%.

[0027] The glass transition temperature (Tg) of the vinyl polymer (A) is preferably 100°C or lower, more preferably 75°C or lower, even more preferably 50°C or lower, still more preferably 25°C or lower, and even more preferably 5°C or lower. The lower limit of the Tg of the vinyl polymer (A) is not particularly limited, but is, for example, -70°C or higher. When the Tg of the vinyl polymer (A) is within the above range, it is preferable in that the ionic conductivity of the electrolyte can be further increased. In this specification, the Tg of the polymer is a value measured by differential scanning calorimetry (DSC).

[0028] <Component (B): Alkali Metal Salt> The alkali metal salt of component (B) is not particularly limited, and examples of the alkali metal constituting the alkali metal salt include lithium, sodium, potassium, rubidium, cesium, and francium, with lithium, sodium, and potassium being preferred, and lithium being more preferred. Examples of the alkali metal salt include LiFSO 4 . ３ alkali metal salts of fluorosulfonic acid such as LiCF ３ SO ３ alkali metal salts of trifluoromethanesulfonic acid such as LiN(FSO ２ ) ２ imide-based alkali metal salts such as LiC(CF ３ SO ２ ) ３ alkali metal salts of perfluoroalkanesulfonylmethides such as LiPF ａ (C ｍ F ２ｍ＋１ ) ６－ａ Fluorophosphates such as LiClO (0≦a≦6, 1≦m≦2); ４alkali metal perchlorates such as LiBF ｂ (C ｎ F ２ｎ＋１ ) ４－ｂ fluoroborates such as (0≦b≦4, 1≦n≦2); alkali metal salts of oxalatoborates such as LiBOB; cyanoborates such as lithium tetracyanoborate; LiAsF ６ , LiI, LiSbF ６ and the like alkali metal salts.

[0029] Among these, imide-based alkali metal salts are preferred, and compounds represented by the following general formula [5] are more preferred: M ｔｌ N (SO ２ R １ ) (SO ２ R ２ ) [5] (In the formula, M ｔｌ represents an alkali metal ion. １ and R ２ are the same or different and represent a fluorine atom or a fluoroalkyl group having 1 to 3 carbon atoms. ｔｌ The alkali metal in R is as described above. １ and R ２ The fluoroalkyl group having 1 to 3 carbon atoms in R 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, and examples thereof 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 ２ As the imide-based alkali metal salt represented by the general formula [5], M is preferably a fluorine atom, a trifluoromethyl group, or a pentafluoroethyl group, more preferably a fluorine atom or a trifluoromethyl group, and even more preferably a fluorine atom. ｔｌ is lithium and R １ and R ２ "Lithium bis(fluorosulfonyl)imide" in which M is a fluorine atom, ｔｌ is lithium and R １ is a fluorine atom and R ２is a trifluoromethyl group, "lithium (fluorosulfonyl) (trifluoromethanesulfonyl) imide" is particularly preferred.

[0030] The solid or gel electrolyte of the present invention contains, as a polymer component, a vinyl polymer (A) having structural units derived from a vinyl monomer containing an ester group and having an ester group ratio of 32 mass% or more as calculated by the above formula (1), together with an alkali metal salt. In this case, even when the alkali metal salt concentration in the solid or gel electrolyte is increased, precipitation of the alkali metal salt is unlikely to occur, and a solid or gel electrolyte with high ionic conductivity can be obtained.

[0031] Specifically, the molar concentration of the (B) component in the solid or gel electrolyte is 2.8 mol / kg or more per 1 kg of electrolyte. If the molar concentration of the (B) component is less than 2.8 mol / kg, the ionic conductivity of the electrolyte may be insufficient, and high output may not be achieved when the electrolyte is applied to a polymer solid electrolyte or polymer gel electrolyte of a lithium ion secondary battery. From this perspective, the molar concentration of the (B) component is preferably 2.9 mol / kg or more per 1 kg of electrolyte, more preferably 3.0 mol / kg or more, even more preferably 3.2 mol / kg or more, and even more preferably 3.3 mol / kg or more. The molar concentration Db [mol / kg] of the (B) component in the solid or gel electrolyte is expressed by the following formula (3): Db = (Mb / WL) (3) where Mb is the number of moles (unit: mol) of the (B) component contained in the solid or gel electrolyte, and WL is the mass (unit: kg) of the solid or gel electrolyte.

[0032] The upper limit of the molar concentration of the (B) component in the solid or gel electrolyte of the present invention can be appropriately set depending on whether the target is a polymer solid electrolyte or a polymer gel electrolyte. For example, in the case of a polymer solid electrolyte, the molar concentration of the (B) component in the polymer solid electrolyte is preferably 4.5 mol / kg or less, more preferably 4.2 mol / kg or less, per 1 kg of electrolyte. In the case of a polymer gel electrolyte, the molar concentration of the (B) component in the polymer gel electrolyte is preferably 5.0 mol / kg or less, more preferably 4.5 mol / kg or less, per 1 kg of electrolyte. By setting the concentration of the (B) component in the electrolyte within the above range, it is possible to prevent local precipitation of alkali metal salts and deterioration of handleability due to increased viscosity.

[0033] <Other Components> The solid or gel electrolyte of the present invention may contain other components as needed in addition to the above-described components (A) and (B).

[0034] [Component (C): Electrolyte] When a polymer gel electrolyte is produced as the solid or gel electrolyte of the present invention, it may further contain an electrolytic solution (component (C)). The polymer gel electrolyte is in a state in which the polymer component is swollen with the electrolytic solution, so that it is possible to suppress leakage while containing the electrolyte, and it is also possible to reduce the amount of volatilization of the electrolytic solution, which is effective in improving safety. As the electrolytic solution, a solvent known as an electrolytic solution for polymer gel electrolytes can be appropriately used.

[0035] Specific examples of component (C) include linear carbonates, cyclic carbonates, cyclic esters, ethers, pyrrolidones, acetonitrile, sulfolane compounds, phosphoric acids, and phosphate esters. Specific examples of linear carbonates include dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Specific examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. Specific examples of cyclic esters include γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone. Specific examples of ethers include 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, and 1,3-dioxolane. The electrolyte may be used alone or in combination of two or more.

[0036] In terms of improving the ionic conductivity of the polymer gel electrolyte, the electrolyte solution is preferably at least one selected from the group consisting of cyclic carbonates, cyclic esters, and cyclic ethers, with cyclic carbonates being particularly preferred.

[0037] The content of the electrolytic solution in the polymer gel electrolyte is usually 25 to 99% by mass, and preferably 30 to 90% by mass, based on the total amount of the polymer gel electrolyte.

[0038] [Component (D): Inorganic Compound] When a polymer gel electrolyte is produced as the solid or gel electrolyte of the present invention, it may further contain an inorganic compound (component (D)). Examples of component (D) include "inorganic oxides, inorganic oxynitrides, inorganic sulfides, inorganic nitrides, inorganic oxycarbides, and inorganic oxycarbonitrides" containing metal elements or nonmetal elements such as silicon, aluminum, titanium, barium, calcium, potassium, zinc, magnesium, niobium, tantalum, tungsten, antimony, tin, boron, yttrium, zirconium, cerium, and phosphorus. The inorganic oxides are preferred because they are easy to handle in the atmosphere.

[0039] Specific examples of the inorganic oxide include silica, alumina, titanium oxide, barium titanate, calcium oxide, zinc oxide, magnesium oxide, niobium oxide, tantalum oxide, tungsten oxide, antimony oxide, etc. The inorganic oxide may also function as an oxide-based inorganic solid electrolyte, for example, LiZr ２ (P.O. ４ ) ３ (hereinafter also referred to as "LZP"), Li １＋ｘ Al ｘ Ti ２-ｘ (P.O. ４ ) ３ , Li １＋ｘ Al ｘ Ge ２-ｘ (P.O. ４ ) ３ The component (D) may be one of these alone or two or more of them in combination in any desired ratio. The content of the inorganic compound in the polymer gel electrolyte is usually 1 to 50 mass %, and preferably 3 to 30 mass %, based on the total amount of the polymer solid or gel electrolyte.

[0040] Other components that may be contained in the solid or gel electrolyte of the present invention include, in addition to the above-mentioned component (D), for example, fillers other than component (D), leveling agents, etc. The content of the other components can be appropriately set depending on each compound, as long as the electrolyte performance is not impaired. In the polymer solid electrolyte, the total mass ratio of component (A), component (B), and component (D) is preferably 95 mass% or more. In addition, in the polymer gel electrolyte, the total mass ratio of component (A), component (B), component (C), and component (D) is preferably 95 mass% or more.

[0041] <<Production of Solid or Gel Electrolyte>> The method for producing the solid or gel electrolyte of the present invention is not particularly limited. Examples of methods for producing the solid or gel electrolyte of the present invention include the following Method 1 and Method 2. [Method 1] A method of curing a curable composition (i.e., a curable composition for solid or gel electrolytes) containing a monomer component as component (a) and the above-mentioned component (B), where the molar concentration of component (B) per 1 kg of the curable composition is 2.8 mol / kg or more. [Method 2] A method of coating a polymer composition containing the above-mentioned components (A) and (B), and a solvent, where the molar concentration of component (B) per 1 kg of the curable composition is 2.8 mol / kg or more, and evaporating the solvent.

[0042] <Curable Composition for Solid or Gel Electrolyte> The curable composition for solid or gel electrolyte (hereinafter also simply referred to as "curable composition") is a curable composition that can form a polymer solid electrolyte and a polymer gel electrolyte by proceeding a curing reaction, for example, by heat or active energy rays. That is, the curable composition may be used as a thermosetting composition or an active energy ray-curable composition. Of these, a thermosetting composition is preferred in that the curable composition can be impregnated into an electrode and then cured in a cell, and an active energy ray-curable composition is preferred in that the curing reaction can proceed easily and sufficiently.

[0043] The curable composition of the present invention contains the following component (a) as a vinyl monomer constituting the polymer component of the polymer solid electrolyte and polymer gel electrolyte, together with component (B) which is an alkali metal salt: Component (a): a vinyl-based monomer component containing a vinyl monomer containing an ester group, and having an ester group ratio calculated by the above formula (2) of 32 mass% or more.

[0044] The component (a) may be any monomer composition capable of obtaining the vinyl polymer (A) by curing a curable composition containing the components (a) and (B). Specifically, the component (a) contains a vinyl monomer M, and may also contain, if necessary, a crosslinkable monomer and a monomer other than the crosslinkable monomer together with the vinyl monomer M. Examples and preferred examples of the vinyl monomer M, the crosslinkable monomer, and the monomer other than the crosslinkable monomer include the same compounds as those exemplified as the monomers constituting the vinyl polymer (A) and the preferred compounds. The mass ratio of the vinyl monomer M and the crosslinkable monomer in the curable composition is the same as the mass ratio of the vinyl monomer M and the crosslinkable monomer to the total structural units of the vinyl polymer (A). The component (a) may contain only one type of vinyl monomer, or may contain two or more types of vinyl monomers.

[0045] In addition to the above-described components (a) and (B), the curable composition may contain other components as needed, provided that the effects of the present invention are not impaired. Examples of other components include the above-described electrolytic solution and a polymerization initiator.

[0046] The electrolyte solution is blended into the curable composition when a polymer gel electrolyte is produced using the curable composition of the present invention. Specific examples of the electrolyte solution blended into the curable composition include the same electrolyte solutions exemplified in the description of the solid or gel electrolyte. When blending the electrolyte solution into the curable composition, the blending ratio of the electrolyte solution is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, per 100 parts by mass of the total amount of the curable composition. The upper limit of the blending ratio of the electrolyte solution is preferably 95 parts by mass or less, more preferably 90 parts by mass or less, per 100 parts by mass of the total amount of the curable composition.

[0047] The polymerization initiator is blended into the curable composition together with component (a) and component (B) for the purpose of sufficiently promoting the polymerization reaction, etc. As the polymerization initiator, known polymerization initiators such as thermal decomposition type and photoinitiation type can be used depending on the means of initiating polymerization. The polymerization initiator contained in the curable composition is preferably a photoinitiation type polymerization initiator (photopolymerization initiator). Specific examples of photopolymerization initiators include benzoin and its alkyl ethers, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones, acylphosphine oxides, α-diketones, and α-hydroxyketones. In order to improve sensitivity to the active energy rays irradiated to obtain the vinyl polymer (A), a benzoic acid-based or amine-based photosensitizer may be used in combination, if necessary.

[0048] When a polymerization initiator is blended into the curable composition, the content of the polymerization initiator in the curable composition can be, for example, 0.1 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the curable composition. From the viewpoint of sufficiently progressing the polymerization reaction, the content of the polymerization initiator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the total amount of the curable composition. When a polymer gel electrolyte is to be obtained, from the viewpoint of appropriately causing gelation, the upper limit of the content of the polymerization initiator is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. When a polymer solid electrolyte is to be obtained, the upper limit is preferably 12 parts by mass or less, more preferably 10 parts by mass or less.

[0049] In addition, in the curable composition, a thermal polymerization initiator and a photopolymerization initiator may be used in combination as the polymerization initiator, and after a curing reaction is carried out with active energy rays, a solid or gel electrolyte may be produced by further performing thermal curing in order to improve the reaction rate.

[0050] The curable composition can be obtained by mixing the above-mentioned component (a) and component (B), as well as other components that are blended as needed. When mixing the components that make up the curable composition, they may be stirred while heated as needed. The temperature when stirring and mixing while heating is preferably in the range of 40 to 90°C. However, when a thermal polymerization initiator is blended into the curable composition, it is preferable to carry out the stirring at a temperature at which the thermal polymerization initiator does not thermally decompose, for example, 30°C or lower, in order to suppress the progress of polymerization during the production of the curable composition.

[0051] Solventless curable compositions that do not contain a solvent such as an organic solvent are preferred because they allow for easy adjustment of the film thickness (e.g., thickening) when using the curable composition to produce a film-like solid or gel electrolyte. Furthermore, curable compositions that contain a solvent such as an organic solvent are preferred because they allow for easy production of a curable composition containing a high concentration of component (B) (in this case, the solvent is referred to as a "solubility promoter for component (B)"), and because they allow for easy production of a solid or gel electrolyte containing a high concentration of component (B) by curing the curable composition while containing the solvent to obtain a cured product, and then removing the solvent from the cured product by heating and / or decompression treatment.

[0052] <Production of Solid or Gel Electrolyte Using Curable Composition> The method for producing a solid or gel electrolyte using the curable composition is not particularly limited. For example, a polymer solid electrolyte or a polymer gel electrolyte can be produced by applying the curable composition of the present invention to a substrate or an electrode (positive electrode, negative electrode), and then curing the curable composition applied to the substrate or the electrode (positive electrode, negative electrode) by irradiating it with active energy rays or by applying heat, or both.

[0053] The substrate can be appropriately selected depending on the application, and a resin film is preferably used. Examples of resin materials constituting the resin film include polyester-based resins (e.g., polyethylene terephthalate (PET)), polyethersulfone-based resins, acetate-based resins, polycarbonate-based resins, and polyolefin-based resins. The coated surface of the substrate to which the curable composition is applied may be subjected to a release treatment. Examples of release treatments include silicone treatment, long-chain alkyl treatment, and fluorine treatment. By using a substrate whose coated surface has been subjected to a release treatment, the solid or gel electrolyte formed on the coated surface can be easily peeled from the substrate.

[0054] Alternatively, for example, a curable composition containing a curable composition, a thermal polymerization initiator, and optionally an SEI-forming additive such as vinylene carbonate or fluoroethylene carbonate may be injected into a pouch cell incorporating a positive electrode, a negative electrode, and a separator, followed by thermal curing of the curable composition. Alternatively, for example, a separator (porous film) may be impregnated with the curable composition, sandwiched between films such as PET films as needed, and irradiated with active energy rays. After polymerization, the films may be removed to form a solid or gel electrolyte between the electrodes. Examples of separator materials include polyethylene (PE, preferably ultra-high molecular weight polyethylene), polypropylene (PP), polyimide, and glass nonwoven fabric.

[0055] Furthermore, for example, an electrode containing a solid or gel electrolyte between electrode active materials may be produced by mixing the curable composition of the present invention with a composition for producing electrodes (positive electrode, negative electrode), applying the resulting curable composition to a current collector, and then curing the composition.

[0056] The coating method can be appropriately selected depending on the coating target and purpose. Examples of coating methods include coating methods using a bar coater, applicator, doctor blade, dip coater, roll coater, spin coater, flow coater, knife coater, comma coater, reverse coater, die coater, lip coater, gravure coater, microgravure coater, and ink jet. The coating amount of the curable composition can be appropriately selected depending on the application, etc., so that the film thickness of the cured product obtained by irradiation with active energy rays is within the desired range.

[0057] When the curing reaction is carried out by irradiation with active energy rays, examples of the active energy rays irradiated to the curable composition include ultraviolet rays, visible light, and electron beams. Of these, ultraviolet rays or electron beams are preferred. The manner in which the active energy is irradiated to the curable composition coated on a substrate or an electrode is not particularly limited. For example, when the curable composition is coated on a substrate, the active energy may be irradiated to only one side or both sides of the substrate coated with the curable composition. The irradiation energy can be appropriately set depending on the type of active energy rays, the formulation of the curable composition, etc.

[0058] Specifically, when ultraviolet rays are used as the active energy rays, the wavelength is, for example, 250 to 400 nm. Examples of ultraviolet irradiation devices include high-pressure mercury lamps, metal halide lamps, ultraviolet electrodeless lamps, and ultraviolet light-emitting diodes (UV-LEDs). The cumulative light amount is 500 mJ / cm. ２ More than 1,000 mJ / cm is preferred. ２ More preferably, 1,500 mJ / cm or more ２ The upper limit of the cumulative light amount is preferably 25,000 mJ / cm from the viewpoint of minimizing the influence on each component in the curable composition and from the viewpoint of reducing energy. ２ Preferably, 20,000 mJ / cm or less ２ The following is more preferred:

[0059] The illuminance and irradiation time of the ultraviolet light can be appropriately set so that the integrated light amount is a desired amount. For example, the illuminance is 0.5 mW / cm ２ More than 1.0 mW / cm is preferable. ２ More preferably, 2.0 mW / cm or more ２ The upper limit of the illuminance is more preferably 100 mW / cm. ２ Preferably, 80 mW / cm or less ２ More preferably, 50 mW / cm or less ２ The following is even more preferred:

[0060] When electron beams are used as the active energy rays, the electron beam irradiation device is not particularly limited, but examples include Cockcroft-Walton type, Van de Graaff type, and resonant transformer type devices. The absorbed dose of the electron beam is preferably 1 to 200 kGy, more preferably 10 to 100 kGy. The acceleration voltage of the electron beam may be appropriately set within a range of 80 to 300 kV depending on the thickness of the substrate or other object to be coated. The oxygen concentration of the electron beam irradiation atmosphere is preferably 500 ppm or less, more preferably 300 ppm or less.

[0061] When the curing reaction is caused to proceed by heat, the heating temperature and heating time can be appropriately set according to the type of polymerization initiator, etc., in accordance with conventional methods for normal radical thermal polymerization. When the thermosetting reaction is caused to proceed after the curable composition is injected into the cell, the heating temperature for thermosetting is preferably 30 to 120°C, and more preferably 40 to 80°C, from the viewpoint of the heat resistance of the pouch cell material. The heating time for thermosetting can be appropriately set according to the type of polymerization initiator, etc.

[0062] When a solid or gel electrolyte membrane is obtained using the curable composition of the present invention, its membrane thickness can be appropriately set depending on the application, etc. The membrane thickness of the solid or gel electrolyte is, for example, 10 μm or more and 5,000 μm or less, and preferably 50 μm or more and 3,000 μm or less.

[0063] <Polymer Composition> The polymer composition used in Method 2 can be obtained by dissolving or dispersing a vinyl polymer (A) as component (A) and a specific alkali metal salt as component (B) in a solvent. An organic solvent can be preferably used as the solvent. Specific examples of the organic solvent include aprotic polar solvents, phenolic solvents, alcoholic solvents, ester solvents, ketone solvents, ether solvents, and hydrocarbon solvents. The organic solvent may be one of these, or a mixed solvent of two or more of these. Furthermore, when producing a polymer gel electrolyte, an electrolytic solution may be used as at least a part of the solvent.

[0064] The method for producing the vinyl polymer (A) to be blended in the polymer composition is not particularly limited. For example, the vinyl polymer (A) may be produced by polymerizing a monomer component containing a vinyl monomer M using a known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization. Alternatively, the vinyl polymer (A) may be produced by curing a mixture of a monomer component containing a vinyl monomer M and a polymerization initiator with heat or active energy rays.

[0065] The solids concentration in the polymer composition (i.e., the ratio of the mass of components other than the solvent in the polymer composition to the total mass of the polymer composition) is not particularly limited, but is preferably 10 to 70 mass%. By setting the solids concentration to 10 mass% or more, an electrolyte membrane having a sufficient thickness can be formed. When the solids concentration is 70 mass% or less, good coatability can be ensured and an electrolyte membrane with a uniform thickness can be easily formed. The solids concentration in the polymer composition is more preferably 15 to 60 mass%, and even more preferably 20 to 50 mass%.

[0066] To produce a polymer solid electrolyte using the polymer composition, first, the polymer composition is applied to a substrate or an electrode (positive electrode, negative electrode) by a known coating method, and the solvent is removed by a drying treatment such as heating or reduced pressure, thereby forming a polymer solid electrolyte on the substrate or electrode. Furthermore, when producing a polymer gel electrolyte using the polymer composition, the polymer gel electrolyte can be produced, for example, by a method in which an electrolyte is formed in the same manner as for a polymer solid electrolyte, and then the electrolyte is brought into contact with an electrolytic solution to swell the polymer component; or a method in which a sol-state polymer composition further containing an electrolytic solution is gelled; or the like.

[0067] <<Characteristics of Solid or Gel Electrolyte>> The solid or gel electrolyte of the present invention exhibits sufficient ionic conductivity even at room temperature (30° C.). Specifically, the ionic conductivity of the solid or gel electrolyte is 1.0×10 at 30° C. －９ S / cm or more, and preferably 1.0×10 －８ S / cm or more, and more preferably 1.0×10 －７ More preferably, it is 1.0×10 S / cm or more. －６ It is even more preferable that the viscosity is 1.0×10 S / cm or more. －５ S / cm or more is more preferable, and 1.0×10 －４ It is more preferable that the ionic conductivity of the solid or gel electrolyte is 200 S / cm or more. In this specification, the ionic conductivity of the solid or gel electrolyte is a value calculated by sandwiching the solid or gel electrolyte between a pair of stainless steel plates and measuring the impedance between the stainless steel plates. Details of the method for measuring the ionic conductivity are as described in the Examples below.

[0068] <Electricity Storage Device> The electricity storage device of the present invention (hereinafter also referred to as "the device") includes a solid or gel electrolyte. Examples of the device include secondary batteries and capacitors. When the device is a secondary battery, one embodiment is a gel battery, and lithium ion secondary batteries, sodium ion secondary batteries, and potassium ion secondary batteries are preferred in terms of excellent ionic conductivity.

[0069] The lithium ion secondary battery of the present disclosure includes the solid or gel electrolyte of the present invention described above. One embodiment of the lithium ion secondary battery includes a positive electrode, a negative electrode, and a solid or gel electrolyte, with the solid or gel electrolyte disposed between the positive electrode and the negative electrode. Materials constituting the positive electrode and the negative electrode are not particularly limited, and can be appropriately selected from known electrode materials for lithium ion secondary batteries. When the solid or gel electrolyte of the present invention is used as an electrolyte in a lithium ion secondary battery, it exhibits high ionic conductivity even at room temperature. Therefore, a lithium ion secondary battery with excellent battery performance and high safety can be obtained. Furthermore, solid or gel electrolytes using polyethylene oxide-based polymers, which are commonly known as solid or gel electrolytes, tend to increase in Tg and lose flexibility as the alkali metal salt concentration increases. In contrast, the solid or gel electrolyte of the present invention has a high alkali metal salt concentration of 2.8 mol / kg or more, yet exhibits high flexibility, making it useful for producing flexible secondary batteries.

[0070] The device may also be a capacitor. One embodiment of the capacitor includes an anode body, a cathode body, and a solid or gel electrolyte, with the solid or gel electrolyte disposed between the anode body and the cathode body so that the solid electrolyte is in contact with the electrode.

[0071] The electricity storage device including the solid or gel electrolyte of the present invention can be used for various purposes, specifically, as a power source for various mobile devices such as mobile phones, personal computers, smartphones, game consoles, and wearable devices; various moving objects such as electric vehicles, hybrid vehicles, robots, and drones; and various electric and electronic devices such as digital cameras, video cameras, music players, power tools, and home appliances.

[0072] The present invention will be specifically described below based on examples. However, the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0073] In the following examples, the reaction rate of the vinyl monomer and the ionic conductivity were measured by the following methods. <Measurement of reaction rate of vinyl monomer> The reaction rate of the acrylic monomer due to active energy ray curing was determined by measurement by the micro ATR method using an infrared absorption spectrum measuring device (Spectrum 100 manufactured by PerkinElmer Japan Co., Ltd.). Specifically, the reaction rate of the acryloyl group was calculated by the following formula (4) using the obtained infrared absorption spectrum. Reaction rate of acryloyl group={1-(B ２ / A ２ ) / (B １ / A １ )}×100 (4) A １ : 1730 cm derived from “—C═O” of the curable composition －１ Peak height B １ : "-CH=CH" of the curable composition ２ " 810 cm comes from －１ Peak height of A ２ : 1730 cm derived from “—C═O” of the cured product －１ Peak height B ２ : "-CH=CH" of the cured product ２ " 810 cm comes from －１ Peak height of

[0074] The reaction rate of the compound represented by the general formula [3] due to active energy ray curing was determined by measuring with a micro ATR method using an infrared absorption spectrometer (Spectrum 100 manufactured by PerkinElmer Japan Co., Ltd.). Specifically, the reaction rate of the vinyl group was calculated using the obtained infrared absorption spectrum according to the following formula (5): Reaction rate of vinyl group = {1 - (B' ２ / A' ２ ) / (B' １ / A' １ )}×100 (5) A' １ : 1730 cm derived from “—C═O” of the curable composition －１ Peak height B' １ : "-CH=CH" of the curable composition ２ " 940 cm comes from －１ Peak height A' ２: 1730 cm derived from “—C═O” of the cured product －１ Peak height B' ２ : "-CH=CH" of the cured product ２ " 940 cm comes from －１ Peak height of

[0075] <Ionic Conductivity Measurement> The obtained polymer solid electrolyte was cut into a circle with a diameter of 6 mm, and sandwiched between two stainless steel plates as electrodes. The impedance between the stainless steel plates was measured at 30°C. For the measurement, an AC impedance method was used in which an AC voltage (applied voltage of 10 mV) is applied between the electrodes to measure the resistance component, and the ionic conductivity was calculated from the real impedance intercept of the obtained Cole-Cole plot. An impedance analyzer (E4990A manufactured by Keysight) was used for the measurement. All of the above operations were carried out in a dry room with a dew point of -60°C. The ionic conductivity (σ) was calculated using the following formula (6): σ = L / (R × S) (6) (In formula (6), σ is the ionic conductivity (unit: S cm －１ ), R is the resistance (unit: Ω), S is the cross-sectional area of ​​the polymer solid electrolyte membrane or polymer gel electrolyte membrane at the time of measurement (unit: cm ２ ), L indicates the distance between the electrodes (unit: cm).

[0076] [Production Example 1] <Lithium zirconium phosphate (LiZr ２ (P.O. ４ ) 3) Production Method> Layered zirconium phosphate (Zr(HPO ４ ) ２ ・H ２4.762 g of ammonium hydroxide, 0.778 g of zirconium oxide, and 0.389 g of lithium carbonate were weighed out, and each sample was placed in a mortar. 25 g of pure water was added and wet-mixed to obtain a mixture. The resulting mixture was dried at 100°C for 2 hours, then transferred to an alumina crucible (capacity 30 mL), heated to 1,100°C over 5.5 hours, and held for 5 hours to perform a first pre-fire. The mixture was then allowed to cool to room temperature to obtain a first pre-fired product. The resulting first pre-fired product was pulverized in a mortar, and 0.3 g of the resulting pulverized first pre-fired product was placed in a 1.2 cm diameter mold and molded into a coin shape using a hydraulic press under a load of 1 ton. The resulting molded product was placed on a platinum plate and heated to 800°C over 30 minutes, then further heated to 1,300°C over 2 hours and held for 6 hours to perform the main firing. After that, the oxide obtained by cooling to room temperature was crushed in a mortar to obtain LiZr ２ (P.O. ４ ) 3 (LZP) powder was obtained.

[0077] 1. Production and Evaluation of Solid or Gel Electrolytes (1) Production of Solid or Gel Electrolytes Using a Curable Composition (Method 1) [Example 1] Lithium bis(fluorosulfonyl)imide (16.84 g) as an alkali metal salt and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (0.5 g) as a photopolymerization initiator were dissolved in 10 g of methyl acrylate (hereinafter also referred to as "MA") as a vinyl monomer to obtain a curable composition for a solid electrolyte (ester group ratio of MA calculated by the above formula (2): 51% by mass). However, the MA used was dehydrated using a molecular sieve. Next, a 300 μm-thick silicone rubber sheet with a 15 mm square opening was placed on a 20 mm square heavy-release release PET film, the composition was poured into it, and the sheet was laminated on top with a light-release release PET film. The composition sandwiched between release PET films on both sides was irradiated with ultraviolet light of 365 nm wavelength (illuminance 56 mW / cm) using an ultraviolet curing device (ultraviolet curing device manufactured by Minaga Electric Manufacturing Co., Ltd., mercury xenon lamp, lamp height 10 mm). ２ ) from the light release film side and the heavy release film side for 30 seconds each, and this was repeated twice (cumulative light amount: 6,720 mJ / cm２ ), and a polymer solid electrolyte (thickness 300 μm) containing polymethyl acrylate (hereinafter also referred to as "pMA") having an ester group ratio of 51 mass% calculated by the above formula (1) was obtained as an active energy ray-cured product. An ultraviolet integrating actinometer (UV Power Puck II manufactured by EIT Corporation (center wavelength of the light-receiving part: 355 nm)) was used to measure the illuminance. The reaction rate of MA was >96%. To suppress moisture absorption, all of the above operations except for the measurement of the vinyl monomer reaction rate were performed in a dry room with a dew point of -60°C. The resulting polymer solid electrolyte membrane had a molar concentration of component (B) per 1 kg of electrolyte of 3.3 mol / kg. Measurement of the ionic conductivity of the polymer solid electrolyte revealed a value of 1.2 × 10 －７ The viscosity was S / cm.

[0078] Examples 2 to 15 and Comparative Examples 1 and 2 Polymer solid electrolytes or polymer gel electrolytes were obtained in the same manner as in Example 1, except that curable compositions for solid or gel electrolytes were prepared by changing the types and amounts of raw materials as shown in Tables 1 and 2. The measurement results of ionic conductivity are shown in Tables 1 and 2.

[0079] Example 16: A curable solid electrolyte composition was obtained by dissolving lithium bis(fluorosulfonyl)imide (28.06 g) as an alkali metal salt and TPO (0.5 g) as a photopolymerization initiator in a mixture of MA (10 g) as a vinyl monomer and acetonitrile (3 g) as an organic solvent. The organic solvent was used as a dissolution promoter for the alkali metal salt, and the MA and acetonitrile were dehydrated using molecular sieves. The same procedure as in Example 1 was then performed to obtain a polymer gel electrolyte. The cured product was then vacuum dried at 60°C for 72 hours to remove the solvent, yielding a polymer solid electrolyte. The ionic conductivity measurement results are shown in Table 1.

[0080] Example 17: A curable solid electrolyte composition was obtained by dissolving lithium bis(fluorosulfonyl)imide (28.06 g) as an alkali metal salt and TPO (0.5 g) as a photopolymerization initiator in a mixture of MA (10 g) as a vinyl monomer and acetonitrile (6 g) as an organic solvent. The organic solvent was used as a dissolution promoter for the alkali metal salt, and the MA and acetonitrile were dehydrated using molecular sieves. The same procedure as in Example 1 was then performed to obtain a polymer gel electrolyte. The cured product was then vacuum dried at 60°C for 72 hours to remove the solvent, yielding a polymer solid electrolyte. The ionic conductivity measurement results are shown in Table 1.

[0081] (2) Production of solid or gel electrolyte by solution casting method (Method 2) [Example 18] A mixture was prepared by dissolving TPO (0.5 g) as a photopolymerization initiator in MA (10 g) as a vinyl monomer (ester group ratio of MA calculated by the above formula (2): 51% by mass). The MA used was dehydrated using a molecular sieve. Next, a 300 μm thick silicone rubber sheet with a 15 mm square opening was placed on a 20 mm square heavy release type release PET film, and the mixture was poured into the sheet, which was then laminated with a light release type release PET film from above. The composition sandwiched between the release PET films on both sides was irradiated with ultraviolet light at a wavelength of 365 nm (illuminance 56 mW / cm) using an ultraviolet curing device (ultraviolet curing device manufactured by Minaga Electric Mfg. Co., Ltd., mercury xenon lamp, lamp height 10 mm). ２ ) from the light release film side and the heavy release film side for 30 seconds each, and this was repeated twice (cumulative light amount: 6,720 mJ / cm ２), and the cured product was pMA with an ester group ratio of 51% by mass, calculated by the above formula (1). Illuminance was measured using an ultraviolet integrating actinometer (UV Power Puck II manufactured by EIT Corporation (center wavelength of the light-receiving element: 355 nm)). The reaction rate of MA was >96%. 0.1 g of the pMA obtained above as component (A) and 0.168 g of lithium bis(fluorosulfonyl)imide as an alkali metal salt were dissolved in 0.3 g of N,N-dimethylformamide. This composition was dropped onto a heavy-release PET film and vacuum-dried at 100°C to remove the N,N-dimethylformamide, yielding a polymer solid electrolyte (thickness: 200 μm). To suppress moisture absorption, all of the above operations, except for the measurement of the vinyl monomer reaction rate, were performed in a dry room with a dew point of -60°C. The resulting polymer solid electrolyte membrane had a molar concentration of component (B) per 1 kg of electrolyte of 3.3 mol / kg, and its ionic conductivity was measured in the same manner as in Example 1 to find that it was 2.8 × 10 －７ The viscosity was S / cm.

[0082]

[0083]

[0084] Details of the compounds used in Tables 1 and 2 are shown below. MA: Methyl acrylate (manufactured by Toagosei Co., Ltd.) EA: Ethyl acrylate (manufactured by Toagosei Co., Ltd.) BA: n-Butyl acrylate (manufactured by Toagosei Co., Ltd.) C-1: 2-Methoxyethyl acrylate (Aclix (registered trademark) C-1, manufactured by Toagosei Co., Ltd.) VAc: Vinyl acetate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) HOA-MS (N): 2-Acryloyloxyethyl succinic acid (HOA-MS (N), manufactured by Kyoeisha Chemical Co., Ltd.) BMA: n-Butyl methacrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) M-309: Trimethylolpropane triacrylate (Aronix (registered trademark) M-309, manufactured by Toagosei Co., Ltd.) TPO: Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (Omirad, manufactured by IGM Resins) TPO H] LiFSI: lithium bis(fluorosulfonyl)imide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) LiFTFSI: (fluorosulfonyl)(trifluoromethanesulfonyl)imide = lithium (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) EC: ethylene carbonate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) PC: propylene carbonate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) BaTiO ３ : Barium titanate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) LZP: Lithium zirconium phosphate produced in Production Example 1

[0085] [Example 19] <<Preparation of Negative Electrode Plate>> Artificial graphite (manufactured by Showa Denko K.K., trade name "SCMG-CF"), SiO (manufactured by Osaka Titanium Technologies Co., Ltd., 5 μm) were used as the active material. In addition, a mixture of styrene / butadiene-based latex (SBR) and carboxymethyl cellulose (CMC) was used as the binder. Water was used as a dilution solvent, and artificial graphite: SiO: SBR: CMC = 77.6: 19.4: 3.0: 1.0 (solid content) was mixed using a planetary mixer (Primix Corporation, Hibismix 2P-03 type) in a mass ratio to prepare a negative electrode mixture slurry with a solid content of 50%. The negative electrode mixture slurry was applied to one side of copper foil (thickness 16.5 μm) and dried to form a mixture layer. Thereafter, the thickness of the mixture layer per side was 50 ± 5 μm, and the mixture density was 1.60 ± 0.10 g / cm ３After rolling the sheet to a thickness of 1 / 4" (3 cm), it was punched out into a 3 cm square to obtain a negative electrode plate. <Preparation of Positive Electrode Plate> NMC532 (LiNi) was used as a positive electrode active material in an N-methylpyrrolidone (NMP) solvent. ０．５ Mn ０．３ Co ０．２ O ２ ), acetylene black as a carbon conductive agent, and polyvinylidene fluoride (PVDF) with an average molecular weight of 1.1 million were mixed in a mass ratio of 100:2:4 using a mixer in the same manner as for the negative electrode to prepare a positive electrode mixture slurry with a solid content of 50%. The prepared slurry was applied to one side of aluminum foil (thickness 20 μm), and after drying, the thickness of the mixture layer per side was 125 μm and the packing density was 3 g / cm. ３After rolling to a thickness of 1 / 4", the battery was punched out into a 3 cm square to obtain a positive electrode plate. <<Battery Fabrication>> The battery was constructed by attaching lead terminals to the positive and negative electrodes, sandwiching a separator (made of polyethylene: film thickness 20 μm, porosity 48%, manufactured by Shenzhen Senior Technology Material Co., Ltd., China) between the two electrodes with the composite layers of the two electrodes facing the separator, placing the battery in an aluminum laminate exterior. The solid electrolyte curable composition prepared in Example 12 was poured into the battery, sealed by heat sealing, and left at 25°C for 24 hours to promote penetration of the curable composition into the electrode. The battery was then left in a constant temperature bath at 60°C for 48 hours to polymerize component (a), resulting in a test battery (pouch-type battery). The design capacity of this battery was 49 mAh. The battery's design capacity was based on a charge cut-off voltage of 4.2 V. <Charge / Discharge Test> The prepared pouch-type battery was placed in a 45 ° C. thermostatic chamber, and a charge / discharge test (BioLogic charge / discharge tester VMP-3) was performed. The first time, CC charging was performed at 0.49 mA, equivalent to a rate of 0.01 C for 49 mAh. After reaching 4.2 V, the charge was switched to CV charging. When the current value dropped to 0.1 mA, charging was stopped and the battery was left for 48 hours to promote the formation of SEI. Then, discharge was performed at 0.01 C to a cut-off voltage of 2.5 V. In the second charge, the capacity was set to 40 mAh, taking into account the irreversible capacity, and charging / discharging was performed at a current value of 0.4 mA (equivalent to 0.01 C) during constant current charging / discharging. After CC charging to 4.2 V, charging was switched to CV charging, and charging was stopped when the current value dropped to 0.1 mA. After leaving it for 30 minutes, the battery was discharged at 0.01 C until the final voltage reached 2.5V.

[0086] 2. Evaluation Results As is clear from the results of Examples 1 to 18, the polymer solid electrolytes of Examples 1 to 13, 16, and 17, in which the ester group ratio of the (A) component was 32 mass% or more and the molar concentration of the (B) component per kg of electrolyte was 2.8 mol / kg or more, and the polymer gel electrolytes of Examples 14 and 15, exhibited high ionic conductivity at 30°C. Among these, when compared with the same vinyl monomer content of the (a) component (Examples 1, 7, 8, 16, and 17), the higher the molar concentration of the (B) component per kg of electrolyte (Example 17) the better the ionic conductivity. Furthermore, the battery fabricated in Example 19 worked.

[0087] In contrast, when the ester group ratio of component (A) was less than 32% by mass, the component (B) could not be dissolved at a molar concentration of 2.8 mol / kg or more relative to 1 kg of electrolyte, and an electrolyte could not be obtained (Comparative Example 1). Furthermore, when the molar concentration of component (B) relative to 1 kg of electrolyte was less than 2.8 mol / kg (Comparative Example 2), the ionic conductivity at 30°C was lower than in Examples 1 to 14, resulting in poor practicality.

[0088] From the above results, it is clear that the polymer solid electrolyte and polymer gel electrolyte of the present invention exhibit high ionic conductivity even at room temperature.

Claims

1. A solid or gel electrolyte comprising the following components (A) and (B), wherein the molar concentration of component (B) per 1 kg of the electrolyte is 2.8 mol / kg or more: Component (A): a vinyl polymer having a structural unit derived from a vinyl monomer containing an ester group, and having an ester group ratio calculated by formula (1) of 32% by mass or more. Component (B): alkali metal salt [Equation 1] (where i = 1, 2, ..., n represents different vinyl monomers; w represents the mass ratio of structural units derived from each vinyl monomer in component (A); w １ +w ２ +...+w ｎ = 1.)

2. The solid or gel electrolyte according to claim 1 , wherein the component (A) is a (meth)acrylic polymer.

3. 2. The solid or gel electrolyte according to claim 1, wherein the component (A) has a structural unit derived from at least one compound selected from the group consisting of a compound represented by the following general formula [1], a compound represented by the general formula [2], a compound represented by the general formula [3], and a compound represented by the general formula [4]: CH ２ =CR １ -C(=O)O-R 2 [1] (In formula [1], R １ represents a hydrogen atom or a methyl group, R ２ represents a saturated organic group having 1 to 4 carbon atoms. １ and R ２ The total number of carbon atoms is 1 to 4.) CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -O-R ３ [2] (In formula [2], R １ and R ３ represents a hydrogen atom or a methyl group. CH ２ =CH-O-C(=O)-R 4 [3] (In formula [3], R ４ represents a saturated organic group having 1 to 4 carbon atoms. CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -OC(=O)-R 5 -C(=O)-OH [4] (In formula [4], R １ represents a hydrogen atom or a methyl group, R ５ represents an organic group having 1 to 6 carbon atoms. １ and R ５ The total number of carbon atoms is 1 to 6.

4. A curable composition used in the production of a solid or gel electrolyte, A curable composition for a solid or gel electrolyte, comprising the following components (a) and (B), wherein the molar concentration of component (B) per 1 kg of the curable composition is 2.8 mol / kg or more: Component (a): A vinyl-based monomer component containing a vinyl monomer containing an ester group, and having an ester group ratio calculated by formula (2) of 32 mass% or more. Component (B): alkali metal salt [Equation 2] (where i = 1, 2, ..., n represents different vinyl monomers; w represents the mass ratio of structural units derived from each vinyl monomer in component (a); w １ +w ２ +...+w ｎ = 1.)

5. The curable composition according to claim 4, wherein the component (a) comprises at least one compound selected from the group consisting of a compound represented by the following general formula [1], a compound represented by the general formula [2], a compound represented by the general formula [3], and a compound represented by the general formula [4]: CH ２ =CR １ -C(=O)O-R 2 [1] (In formula [1], R １ represents a hydrogen atom or a methyl group, R ２ represents a saturated organic group having 1 to 4 carbon atoms. １ and R ２ The total number of carbon atoms is 1 to 4.) CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -O-R ３ [2] (In formula [2], R １ and R ３ represents a hydrogen atom or a methyl group. CH ２ =CH-O-C(=O)-R 4 [3] (In formula [3], R ４ represents a saturated organic group having 1 to 4 carbon atoms. CH ２ =CR １ -C(=O)O-(CH ２ ) ２ -OC(=O)-R 5 -C(=O)-OH [4] (In formula [4], R １ represents a hydrogen atom or a methyl group, R ５ represents an organic group having 1 to 6 carbon atoms. １ and R ５ The total number of carbon atoms is 1 to 6.

6. The curable composition according to claim 4 , wherein the composition is an active energy ray-curable composition.

7. A solid or gel electrolyte which is a cured product of the composition according to claim 4.

8. An electricity storage device comprising the solid or gel electrolyte according to any one of claims 1 to 3 and 7.

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