Solid electrolyte medium, composition for solid electrolyte, and secondary battery

Abstract

The purpose of the present disclosure is to provide a solid electrolyte medium and a composition for a solid electrolyte that make it possible to prepare a solid electrolyte which exhibits good ion conductivity and has high film strength, and further to provide a secondary battery that includes the solid electrolyte medium. Provided is a solid electrolyte medium that constitutes a solid electrolyte of an all solid state battery and comprises a polyurethane resin (U) which includes a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B), wherein the polyol compound (A) includes a polyol compound (A1) having a PTME unit.

Description

Solid electrolyte medium, solid electrolyte composition and secondary battery

[0001] The present disclosure relates to a solid electrolyte medium, a solid electrolyte composition, a secondary battery, and the like.

[0002] In recent years, there has been a strong desire to reduce carbon dioxide emissions in order to protect the environment. The automotive industry is looking forward to reducing carbon dioxide emissions through the introduction of electric vehicles (EVs), hybrid electric vehicles (HEVs), and the like, and is actively developing secondary batteries for driving motors, which hold the key to realizing these vehicles. Furthermore, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as their power sources has increased significantly. As a secondary battery for such applications, lithium-ion (secondary) batteries, which can achieve high energy density and high power density, have been attracting attention.

[0003] Most current lithium-ion secondary batteries use a liquid electrolyte, i.e., an electrolyte solution, in which a lithium electrolyte salt is dissolved in an electrolyte solvent primarily consisting of propylene carbonate, ethylene carbonate, etc. The electrolyte solution is an organic solvent-based electrolyte solution using an organic solvent as a medium, and batteries using such an electrolyte solution have safety issues, such as the risk of electrolyte leakage (leakage) and the risk of explosion, leakage, or fire due to an increase in internal pressure caused by a rise in temperature. Therefore, there has been active development of solidifying the electrolyte solution, i.e., solid electrolytes.

[0004] For example, Patent Document 1 proposes a polymer electrolyte composition containing a polyurethane resin (U) having a number average molecular weight of 1,000 to 500,000, obtained by reacting a polyether diol (A) having a number average molecular weight of 500 to 100,000 with an organic diisocyanate (B) as essential components, and a lithium salt. Patent Document 1 describes that a polymer electrolyte composition containing a polyurethane resin can achieve both high ionic conductivity at room temperature and cycle life characteristics.

[0005] Patent Document 2 proposes a polyurethane solid electrolyte comprising (A) a polyurethane containing, as a polyol component, a polycarbonate polyurethane polyol obtained by reacting (a) a polyalkylene carbonate polyol and / or (b) a polyalkylene carbonate polyol with a polyisocyanate, (B) an electrolyte salt, and (C) a nonaqueous organic solvent capable of dissolving the electrolyte salt. Patent Document 2 describes that polycarbonate-based polyurethane resins have high ionic conductivity and excellent mechanical strength.

[0006] However, in Patent Documents 1 and 2, it is necessary to use an organic solvent-based electrolyte solution in order to obtain high ionic conductivity, and the risk of fire remains unresolved.

[0007] In order to further improve safety, all-solid-state batteries using solid electrolytes that do not contain liquid electrolytes (electrolytic solutions) are also being developed. Patent Document 3 proposes a polymer electrolyte composition that does not use electrolytic solutions, and the polymer electrolyte composition contains a polymer of an acrylic monomer composition as the polymer. The polymer material used in Patent Document 3 is an acrylic material, and there is no mention of polyurethane materials.

[0008] JP 2016-069388 A JP 2001-076736 A JP 2021-118180 A

[0009] The solid electrolytes using resins described in Patent Documents 1 and 2 use an organic solvent-based electrolyte solution to achieve high ionic conductivity, so there is still a risk of battery fire. Furthermore, in all-solid-state batteries using solid electrolytes that do not contain an electrolyte solution, repeated charge and discharge causes dendrites to grow from the negative electrode, which then come into contact with the positive electrode and cause a short circuit. Therefore, in order to put such solid electrolytes into practical use, they need to have not only high ionic conductivity but also strength to prevent short circuits caused by dendrites.

[0010] The present disclosure aims to provide a solid electrolyte medium and a composition for a solid electrolyte, which can produce a solid electrolyte that exhibits good ionic conductivity and also has strong film strength, and further to provide a secondary battery having the solid electrolyte medium.

[0011] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by providing a solid electrolyte medium for constituting a solid electrolyte of an all-solid-state battery, the solid electrolyte medium containing a polyurethane resin (U) including a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B), wherein the polyol compound (A) includes a polyol compound (A1) having a structural unit (hereinafter sometimes referred to as a PTME unit) represented by the following formula (1), and the degree of polymerization n of the PTME unit in the polyol compound (A1) having the PTME unit is 2 or more. The present disclosure has been completed as a result of further research based on these findings.

[0012] (In the formula, n is an integer of 2 or more.)

[0013] That is, the present disclosure is as follows: [1] A solid electrolyte medium constituting a solid electrolyte of an all-solid-state battery, the solid electrolyte medium containing a polyurethane resin (U) including a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B), wherein the polyol compound (A) includes a polyol compound (A1) having a structural unit represented by the following formula (1):

[0014] (In the formula, n is an integer of 2 or more.)

[0015] [2] The solid electrolyte medium according to [1], wherein the polyol compound (A1) is polytetramethylene ether glycol or polyether polycarbonate diol. [3] The solid electrolyte medium according to [1] or [2], wherein the content of the polyol compound (A1) having the structural unit represented by formula (1) in the polyol compound (A) is 1% by mass or more and 100% by mass or less. [4] The solid electrolyte medium according to any one of [1] to [3], wherein the content of the structural unit represented by formula (1) in the polyol compound (A1) having the structural unit represented by formula (1) is 80% by mass or more and 99.9% by mass or less. [5] The solid electrolyte medium according to any one of [2] to [4], wherein the polyol compound (A1) having the structural unit represented by formula (1) is polyether polycarbonate diol, and the content of the structural unit represented by formula (1) in the polyol compound (A1) is 80% by mass or more and 99.9% by mass or less. [6] A solid electrolyte composition for an all-solid-state battery, comprising: a solid electrolyte medium containing a polyurethane resin (U) having a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B); and a metal salt (C), wherein the polyol compound (A) contains a polyol compound (A1) having a structural unit represented by the following formula (1):

[0016] (In the formula, n is an integer of 2 or more.)

[0017] [7] The composition for a solid electrolyte according to [6], wherein the weight ratio of the polyurethane resin (U) to the metal salt (C) in the composition for a solid electrolyte is polyurethane resin / metal salt = 20 / 80 to 95 / 5. [8] The composition for a solid electrolyte according to [6] or [7], wherein the metal salt (C) is an alkali metal salt. [9] The composition for a solid electrolyte according to any one of [6] to [8], wherein the metal salt (C) is a lithium salt.

[10] A secondary battery having the solid electrolyte medium according to any one of [1] to [5].

[0018] According to the present disclosure, a solid electrolyte medium and a composition for a solid electrolyte are provided that can produce a solid electrolyte that exhibits good ionic conductivity and also has strong film strength, and further a secondary battery having the solid electrolyte medium is provided.

[0019] The present disclosure will be described in detail below.

[0020] Solid Electrolyte Medium In a battery, an electrolyte refers to a substance that transports charge carriers between a positive electrode and a negative electrode. In the present disclosure, a solid electrolyte containing a metal salt, which is an electrolyte salt, and a solid electrolyte medium, but not containing a liquid component such as an electrolytic solution, is used as the electrolyte. Furthermore, a battery containing such a solid electrolyte is an all-solid-state battery. Therefore, the solid electrolyte medium of the present disclosure constitutes the solid electrolyte of the all-solid-state battery.

[0021] The solid electrolyte medium of the present disclosure is a solid electrolyte medium constituting a solid electrolyte of an all-solid-state battery, which contains a polyurethane resin (U) including a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B), and the polyol compound (A) includes a polyol compound (A1) having a PTME unit.

[0022] Polyurethane Resin (U) Polyol Compound (A) The polyol compound (A) contains a polyol compound (A1) having a PTME unit (hereinafter, also referred to as a "PTME unit-containing polyol compound") The PTME (polytetramethylene ether) unit is a structural unit represented by the following formula (1):

[0023]

[0024] n is usually an integer of 2 or more, preferably 2 or more and 139 or less, more preferably 5 or more and 70 or less, and particularly preferably 8 or more and 65 or less.

[0025] The PTME unit-containing polyol compound (A1) is not particularly limited, and examples thereof include polytetramethylene ether glycol, polyether polycarbonate diol, and the like.

[0026] The polytetramethylene ether glycol may be a commercially available product. Examples of commercially available products include PTMG250, PTMG650, PTMG850, PTMG1000, PTMG1300, PTMG1500, PTMG1800, PTMG2000, PTMG3000, and PTMG4000 manufactured by Mitsubishi Chemical Corporation. The polyether polycarbonate diol may be a commercially available product. Examples of commercially available products include PEPCD NT2006, PEPCD NT2002, and PEPCD NT1002 manufactured by Mitsubishi Chemical Corporation.

[0027] The PTME unit content in the PTME unit-containing polyol compound (A1) is preferably 80% by mass or more and 99.9% by mass or less.

[0028] The PTME unit-containing polyol compound (A1) is preferably polytetramethylene ether glycol or polyether polycarbonate diol.

[0029] When the PTME unit-containing polyol compound (A1) is polytetramethylene ether glycol, the PTME unit content is preferably 80% by mass or more and 99.9% by mass or less, more preferably 92% by mass or more and 99.8% by mass or less, and even more preferably 96% by mass or more and 99.6% by mass or less. When the PTME unit-containing polyol compound (A1) is polyether polycarbonate diol, the PTME unit content is preferably 80% by mass or more and 99.9% by mass or less, more preferably 82% by mass or more and 98% by mass or less, and even more preferably 84% by mass or more and 96% by mass or less.

[0030] The average molecular weight of the PTME unit-containing polyol compound (A1) is not particularly limited, but is usually 150 or more, preferably 160 to 10,000, more preferably 400 to 5,000, even more preferably 600 to 4,700, and particularly preferably 1,500 to 3,500.

[0031] The molecular weight and degree of polymerization of the PTME unit contained in the polyurethane resin or polyether polycarbonate diol can be confirmed by the following method: 1 H-NMR measurement, GPC measurement, etc. 1 For H-NMR measurement, the polyurethane resin, or components previously decomposed or separated into structural units by hydrolysis, are dissolved in a deuterated solvent and the measurement is performed, thereby confirming the degree of polymerization of the PTME units. Regarding the hydrolysis method, in the decomposition method under basic conditions, 1 g of polyurethane resin is placed in a pressure decomposition vessel together with 20 mL of 20% aqueous sodium hydroxide solution, and thermally decomposed at 160 to 180°C for 12 hours. After cooling, the mixture is extracted with chloroform, and 2N hydrochloric acid is added to the obtained organic layer 1, followed by a liquid separation operation. Furthermore, the polyether diol that constitutes the polyurethane resin is obtained in the obtained organic layer 2. The obtained polyether diol is then 1 H-NMR or GPC measurement is performed. Regarding GPC measurement, the molecular weight or degree of polymerization can be confirmed by measuring the polyether diol obtained by the hydrolysis method.

[0032] The polyol compound (A) may contain a polyol compound (A2) other than the PTME unit-containing polyol compound (A1).

[0033] The other polyol compound (A2) is not particularly limited as long as it is a compound having two or more hydroxyl groups (—OH) in one molecule. Examples of the other polyol compound (A2) include polyhydric alcohols, polyether polyols, polyester polyols, polyether ester polyols, polycarbonate polyols, polyacrylic polyols, polyacetal polyols, polybutadiene polyols, polysiloxane polyols, and fluorine polyols. The polyhydric alcohol is not particularly limited. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, polyoxyethylene glycol, 1,4-butanediol, propylene glycol, neopentyldiol, hexanediol, bisphenol A, bisphenol B, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether, dimethylolpropionic acid, trimethylolpropane, glycerin, and pentaerythritol. The polyether polyol is not particularly limited. Examples of polyether polyols include alkylene derivatives of polyhydric alcohols and polythioether polyols. The polyester polyol or polyether ester polyol is not particularly limited. Examples of polyester polyols or polyether ester polyols include polyhydric alcohols, polycarboxylic acids, polycarboxylic anhydrides, polyether polyols, esters of polycarboxylic acid esters, castor oil polyols, polycaprolactone polyols, and polyalkylene carbonate diols. These can be used alone or in combination of two or more.

[0034] The content of the polyol compound (A1) having a PTME unit in the polyol compound (A) is preferably 1% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 100% by mass or less, and even more preferably 70% by mass or more and 99% by mass or less.

[0035] Monool Compound (D) The polyurethane resin may have a structure derived from a monool compound (D) in addition to a structure derived from the polyol compound (A). The monool compound (D) is a compound containing one hydroxyl group. Examples of the other monool compound (D) include polyoxyethylene monomethyl ether, polyoxyethylene polyoxypropylene butyl ether, 2-hydroxyethyl methacrylate, and alcohols such as methanol, ethanol, isopropyl alcohol, and butanol. These may be used alone or in combination of two or more. When the monool compound (D) is contained, it is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the polyol compound (A).

[0036] Polyisocyanate Compound (B) The polyisocyanate compound (B) is a compound having two or more isocyanate groups (-NCO) in one molecule. Any polyisocyanate compound conventionally used in the production of polyurethanes can be used as the polyisocyanate compound (B) without any particular restrictions. Examples of the polyisocyanate compound (B) include organic polyisocyanate compounds such as aromatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. The organic polyisocyanate compound may be a bifunctional compound, i.e., a compound having two isocyanate groups (-NCO) in one molecule, such as an aromatic diisocyanate, an araliphatic diisocyanate, an alicyclic diisocyanate, or an aliphatic diisocyanate. In addition, a compound having three or more functional groups, i.e., a compound having three or more isocyanate groups (-NCO) in one molecule, such as an aromatic polyisocyanate, an araliphatic polyisocyanate, an alicyclic polyisocyanate, or an aliphatic polyisocyanate, can be used. The polyisocyanate compound (B) may be used alone or in combination of two or more types.

[0037] Examples of the aromatic diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0038] Examples of the aromatic aliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate, mixtures thereof, 1,3- or 1,4-bis(1-isocyanate-1-methylethyl)benzene, and mixtures thereof.

[0039] Examples of the alicyclic diisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and 1,4-bis(isocyanatomethyl)cyclohexane.

[0040] Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate.

[0041] Examples of the tri- or higher functional aromatic polyisocyanate include trifunctional aromatic polyisocyanates such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and tetrafunctional aromatic polyisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0042] Examples of the tri- or higher functional aromatic aliphatic polyisocyanate include trifunctional aromatic alicyclic polyisocyanates such as 1,3,5-triisocyanate methylbenzene.

[0043] Examples of the trifunctional or higher alicyclic polyisocyanate include 1,3,5-triisocyanate cyclohexane, 1,3,5-trimethylisocyanate cyclohexane, 2-(3-isocyanate propyl)-2,5-di(isocyanate methyl)bicyclo(2.2.1)heptane, 2-(3-isocyanate propyl)-2,6-di(isocyanate methyl)bicyclo(2.2.1)heptane, 3-(3-isocyanate propyl)-2,5-di(isocyanate methyl)bicyclo(2.2.1)heptane, 5-(2-isocyanate ethyl)bicyclo(2.2.1)heptane, )-2-isocyanatemethyl-3-(3-isocyanatepropyl)bicyclo(2.2.1)heptane, 6-(2-isocyanateethyl)-2-isocyanatemethyl-3-(3-isocyanatepropyl)bicyclo(2.2.1)heptane, 5-(2-isocyanateethyl)-2-isocyanatemethyl-2-(3-isocyanatepropyl)bicyclo(2.2.1)heptane, 6-(2-isocyanateethyl)-2-isocyanatemethyl-2-(3-isocyanatepropyl)bicyclo(2.2.1)heptane, and the like.

[0044] Examples of the tri- or higher functional aliphatic polyisocyanates include trifunctional aliphatic polyisocyanates such as lysine ester triisocyanate, 1,4,8-triisocyanato octane, 1,6,11-triisocyanato undecane, 1,8-diisocyanato-4-isocyanato methyl octane, 1,3,6-triisocyanato hexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanato methyl octane.

[0045] In addition to the above, derivatives of isocyanate compounds can also be used as polyisocyanates. Examples of such derivatives of isocyanate compounds include dimers, trimers, biuret, allophanates, carbodiimides, polymethylene polyphenyl polyisocyanates (crude MDI or polymeric MDI), crude TDI, and adducts of isocyanate compounds and low-molecular-weight polyols (e.g., trimethylolpropane).

[0046] The molar ratio of the hydroxyl groups of (A) and (D) to the isocyanate groups of (B) (R value: NCO groups / OH groups) is preferably 0.5 to 4, more preferably 0.8 to 3, and particularly preferably 0.9 to 2.

[0047] By using the solid electrolyte medium of the present disclosure, a solid electrolyte having good ionic conductivity and strong film strength can be obtained without using an organic solvent-based electrolyte solution.

[0048] 1. Solid Electrolyte Composition for All-Solid-State Battery In this specification, the solid electrolyte composition is a composition used for producing (molding) a solid electrolyte. When used in dry molding such as powder coating or injection molding, the composition may be in a (semi-)solid state such as powder or paste. When used in wet molding such as coating or casting, the composition may be in a liquid state that becomes a solid electrolyte by drying or heating. The composition may contain a liquid medium such as water or an organic solvent as needed. Examples of solid electrolyte compositions used in the wet molding include coating liquids. Here, the solid electrolyte is used as an electrolyte for an all-solid-state battery. The solid electrolyte composition is a solid electrolyte composition for an all-solid-state battery, comprising: a solid electrolyte medium containing a polyurethane resin (U) having a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B); and a metal salt (C), wherein the polyol compound (A) contains a polyol compound (A1) having a PTME unit, and the degree of polymerization n of the polyol compound (A1) having the PTME unit is 2 or more.

[0049] The solid electrolyte medium containing the polyurethane resin (U) of the present disclosure is in a solid state containing no liquid component when forming the solid electrolyte, but the properties of the solid electrolyte composition when it is prepared vary depending on the molding method. In the case of a solid electrolyte composition for dry molding, it may be used in a (semi-)solid state such as a powder or paste. In the case of a solid electrolyte composition for wet molding, it is preferable that the polyurethane resin be dispersed or dissolved in a liquid to facilitate molding, and therefore it is preferably in the form of a liquid containing the polyurethane resin. The liquid containing the polyurethane resin, which is a preferred embodiment of the solid electrolyte medium of the present disclosure, is not particularly limited as long as the liquid can be removed by drying. For example, an aqueous dispersion of a polyurethane resin (hereinafter sometimes referred to as an "aqueous dispersion polyurethane resin"), a solution of a polyurethane resin dissolved in a solvent (hereinafter sometimes referred to as a "solvent-based polyurethane resin"), etc. can be used.

[0050] Known methods can be used to produce water-dispersible polyurethane resins. For example, polyol compound (A), polyisocyanate compound (B), and, if necessary, a hydrophilic group-containing compound are reacted, and the hydrophilic groups are neutralized or quaternized with a quaternizing agent to obtain a urethane prepolymer, which is then emulsified with water and / or a polyamine for chain extension. When reacting polyol compound (A) and polyisocyanate compound (B), a solvent may be used as needed. Any organic solvent can be used as the solvent. Examples of organic solvents include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, and butyl acetate. The reaction conditions are, for example, 60°C to 80°C for about 2 to 4 hours, preferably about 70°C for about 3 hours, and the mixture can be cooled to 5°C to 45°C as needed, followed by the next step (neutralization or quaternization of the hydrophilic groups).

[0051] To promote the reaction, known urethanization catalysts can be used without limitation. Examples of urethanization catalysts include inorganic metal catalysts, organometallic catalysts, and amine catalysts. Examples of inorganic metal catalysts include inorganic tin catalysts and inorganic bismuth catalysts. Examples of organometallic catalysts include organotin catalysts, organolead catalysts, and organobismuth catalysts. Examples of organotin catalysts include dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin diacetate. Examples of organolead catalysts include lead octoate, lead octenoate, and lead naphthenate. Examples of organobismuth catalysts include bismuth octoate and bismuth neodecanoate. Examples of amine catalysts include diethylenetriamine, triethylamine, and N,N-dimethylcyclohexylamine.

[0052] The molar equivalent ratio of isocyanate groups to hydroxyl groups used to obtain the urethane prepolymer is not particularly limited, as long as the ratio is isocyanate groups:hydroxyl groups = 1.0 or more: 1. A ratio of 1.05 to 3:1 is preferred, and a ratio of 1.20 to 2.2:1 is more preferred, since this allows the urethane prepolymer to have a low viscosity and a stable emulsion to be obtained.

[0053] The hydrophilic group may be an anionic group, a cationic group, or a nonionic group. The hydrophilic group-containing compound for incorporating and introducing the hydrophilic group is not particularly limited. Examples of the hydrophilic group-containing compound include (di)alkanolcarboxylic acid or sulfonic acid neutralized with a tertiary amine or alkali metal, (methoxy)polyalkylene oxide, (di)alkanolamine organic acid or inorganic acid neutralized product, and quaternary ammonium salts obtained by reacting these with alkyl halide or dialkyl sulfate. Among these, (di)alkanolcarboxylic acid or sulfonic acid neutralized with a tertiary amine or alkali metal, (di)alkanolamine organic acid or inorganic acid neutralized product, and quaternary ammonium salts obtained by reacting these with alkyl halide or dialkyl sulfate are preferred. The (methoxy)polyalkylene oxide only needs to contain at least ethylene oxide as the alkylene oxide, and may also contain alkylene oxides other than ethylene oxide, such as propylene oxide and butylene oxide. When a (methoxy)polyalkylene oxide containing a plurality of types of alkylene oxides is used, the addition form (form of introduction of hydrophilic groups) may be either block addition or random addition.

[0054] Examples of compounds into which these hydrophilic groups can be introduced include the following. Examples of anionic types include salts obtained by neutralizing carboxylic acid compounds such as dimethylolpropionic acid, dimethylolbutanoic acid, lactic acid, and glycine; and sulfonic acid compounds such as polyester diols composed of aminoethylsulfonic acid and sulfoisophthalic acid and a diol with tertiary alkanolamines such as triethylamine, diisopropylethylamine, lithium hydroxide or its hydrate, sodium hydroxide, and dimethylaminoethanol. Among these, preferred are sodium salts of dimethylolpropionic acid, glycine, and aminoethylsulfonic acid. Examples of cationic types include salts obtained by neutralizing alkanolamines such as dimethylaminoethanol and methyldiethanolamine with organic carboxylic acids such as formic acid and acetic acid, or inorganic acids such as hydrochloric acid and sulfuric acid; and salts obtained by quaternizing alkanolamines such as dimethylaminoethanol and methyldiethanolamine with alkyl halides such as methyl chloride and methyl bromide, or dialkyl sulfates such as dimethyl sulfate. Among these, combinations of methyldiethanolamine and an organic carboxylic acid and combinations of methyldiethanolamine and dimethyl sulfate are preferred due to their ease of industrial production. The content of the hydrophilic group in the urethane prepolymer is not particularly limited, and is preferably 0.01 to 2.5 mmol / g, more preferably 0.02 to 1.8 mmol / g, and even more preferably 0.03 to 1.6 mmol / g.

[0055] The amount of water used for the emulsification is preferably about 100 to 900 parts by mass per 100 parts by mass of the urethane prepolymer.

[0056] A known chain extender can be used for the chain extension. Examples of the chain extender include water, ammonia, and polyamines. The polyamines are not particularly limited and include aliphatic polyamines such as ethylenediamine, trimethylenediamine, propylenediamine, diethylenetriamine, and triethylenetetramine; aromatic polyamines such as metaxylenediamine, tolylenediamine, and diaminodiphenylmethane; alicyclic polyamines such as piperazine and isophoronediamine; and polyhydrazides such as hydrazine and adipic acid dihydrazide. The chain extenders may be used alone or in combination. The chain extension conditions are, for example, about 40°C to 60°C for about 0.5 to 2 hours, preferably about 50°C for about 1 hour.

[0057] The solid content of the polyurethane resin in the water-dispersible polyurethane resin is not particularly limited, and is, for example, preferably 1 to 60 mass %, more preferably 3 to 55 mass %, and even more preferably 4 to 50 mass %, based on the total amount of the water-dispersible polyurethane resin.

[0058] Known methods can be used to produce solvent-based polyurethane resins. For example, a PTME unit-containing polyol compound (A1) and a polyisocyanate compound (B) are mixed in a solvent (solvent), reacted, and then another polyol compound (A2) and / or a monool compound (D) is added and mixed. The hydroxyl group-containing compound is added to consume any remaining isocyanate groups, and the reaction is continued until the isocyanate group concentration reaches 0%. Any organic solvent can be used as the solvent (solvent). Examples of organic solvents include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, N,N-dimethylacetamide, ethyl acetate, and butyl acetate. Examples of other polyol compounds (A2) or monool compounds (D) include the compounds described above, such as 1,4-butanediol. The reaction conditions are typically about 20°C to 150°C for about 1 to 5 hours, preferably about 20°C to 30°C for about 2 to 4 hours. The conditions for the isocyanate group consumption step are, for example, about 40° C. to 60° C. for 12 hours or more. The solid content of the polyurethane resin in the solvent-based polyurethane resin is not particularly limited, and is, for example, preferably 1 to 60 mass %, more preferably 3 to 55 mass %, and even more preferably 4 to 50 mass %, based on the total amount of the solution-based polyurethane resin.

[0059] The water-dispersible polyurethane resin or the solvent-based polyurethane resin may contain various commonly used additives, if necessary. Examples of such additives include weathering agents, antibacterial agents, antifungal agents, pigments, inorganic fillers, organic fillers, rust inhibitors, dyes, film-forming aids, inorganic crosslinking agents, organic crosslinking agents (e.g., blocked isocyanate crosslinking agents, epoxy crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, melamine crosslinking agents, etc.), silane coupling agents, antiblocking agents, viscosity modifiers, leveling agents, antifoaming agents, dispersion stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, plasticizers, lubricants, and antistatic agents.

[0060] The acid value of the water-dispersible polyurethane resin or solvent-based polyurethane resin is preferably in the range of 0 to 50 mgKOH / g, more preferably in the range of 5 to 40 mgKOH / g. The acid value is a numerical value obtained by titrating a polyurethane resin having carboxy groups dissolved in an appropriate solvent with an alkali such as potassium hydroxide, and serves as an index of the carboxy group content. The acid value can also be calculated from the amounts of raw materials used in the synthesis of the polyurethane resin.

[0061] Metal Salt (C) In the present disclosure, any metal salt that has been conventionally used as an electrolyte salt in batteries can be used. Examples of the metal salt include alkali metal salts such as lithium salts, sodium salts, and potassium salts. Specific examples of lithium salts include LiBr, LiCl, LiI, LiSCN, and LiBF. ４ , LiAsF ６ , LiClO ４ , C.H. ３ COOLi, CF ３ COOLi, LiCF ３ SO ３ , LiPF ６ , LiN(CF ３ SO ２ ) ２ Specific examples of sodium salts include NaBr, NaCl, NaI, NaSCN, and NaBF ４ , NaAsF ６ , NaClO ４ , C.H. ３ COONa, CF ３ COONa, NaCF ３ SO ３ , NaPF ６ , NaN(CF ３ SO ２ ) ２ Specific examples of potassium salts include KBr, KCl, KI, KSCN, and KBF. ４ , KAsF ６ , KClO ４ , C.H. ３ COOK, C.F. ３ COOK, KCF ３ SO ３ , KPF ６ , KN(CF３ SO ２ ) ２ The metal salts may be used alone or in combination of two or more. The metal salt is preferably a lithium salt.

[0062] The content of the polyurethane resin (U) in the solid electrolyte composition is preferably 1 to 80 mass %, more preferably 5 to 60 mass %, based on the mass of the solid electrolyte composition.

[0063] The weight ratio of the polyurethane resin (U) to the metal salt (C) in the solid electrolyte composition is preferably polyurethane resin (U) / metal salt (C)=5 / 95 to 95 / 5, and more preferably 10 / 90 to 70 / 30.

[0064] The solid electrolyte composition of the present disclosure may further contain additives such as plasticizers, stabilizers, antioxidants, and release agents that are used in known polymer compounds, within a range that does not contradict the object of the present disclosure.

[0065] The method for producing the solid electrolyte composition of the present disclosure is not particularly limited. For example, the solid electrolyte composition can be obtained by mixing the water-dispersible polyurethane resin or solvent-based polyurethane resin, which is a solid electrolyte medium, with the metal salt in a predetermined ratio. The mixing can be performed by a conventionally known method, for example, using a mixer such as a homomixer, homodisper, wave rotor, homogenizer, disperser, paint conditioner, ball mill, magnetic stirrer, or mechanical stirrer.

[0066] The solid electrolyte composition of the present disclosure is suitable for use in molding a solid electrolyte. A solid electrolyte molded body obtained by dry molding or wet molding using the solid electrolyte composition can have various forms depending on the intended use. Examples of the form include a membrane, a plate, a fiber, a hollow fiber, a particle, a block, a microporous form, a foam, and the like.

[0067] Solid Electrolyte: A solid electrolyte obtained by wet molding using a liquid solid electrolyte composition containing a liquid medium such as water or an organic solvent is obtained by drying the solid electrolyte composition. By drying the solid electrolyte composition, the liquid medium contained in the solid electrolyte composition is removed, resulting in a solid electrolyte containing a metal salt and a polyurethane resin, which is the solid content of the solid electrolyte medium. It is desirable to remove all of the liquid medium contained in the solid electrolyte composition by drying during molding of the solid electrolyte. However, it is acceptable for the liquid medium to remain in the solid electrolyte to the extent that it does not pose safety issues such as the risk of electrolyte leakage (leakage) in the battery, or the risk of leakage, explosion, or fire due to an increase in internal pressure when the temperature increases (less than 1% by mass of the electrolyte). The drying temperature and drying time are not particularly limited as long as the water or solvent contained in the solid electrolyte composition is substantially removed. The drying temperature is typically 40°C or higher, preferably 50°C to 110°C. Drying at a low temperature (approximately 50°C) and then drying at a high temperature (approximately 110°C) may be performed. The drying time is, for example, 24 hours or more, preferably 24 to 30 hours. The water content in the solid electrolyte can be confirmed, for example, by Karl Fischer moisture content measurement (vaporization method). In this method, the water in the solid electrolyte is vaporized using a moisture vaporizer, and the vaporized water is introduced into a titration cell using a carrier gas (nitrogen, etc.), and the water content can be measured. (Apparatus used: Metrohm 899 coulometer (with one-liquid electrode), 866KF Thermoprep (resistance temperature detector temperature control unit)). The solvent content in the solid electrolyte can be confirmed, for example, by headspace gas chromatography (HS-GC). In this method, the solvent in the solid electrolyte is vaporized using a headspace unit, and the vaporized solvent is injected into a packed column using a carrier gas (hydrogen, helium, etc.), and the solvent content can be measured. (Devices used: Shimadzu Corporation GC-14A (gas chromatography), AOC-14 AUTO INJECTOR (headspace unit))

[0068] The ionic conductivity of the solid electrolyte is usually 0.1 μS / cm or more, preferably 0.5 μS / cm or more, and more preferably 1 μS / cm or more.

[0069] The puncture strength of the solid electrolyte is usually 30 cN or more, preferably 40 cN or more, and more preferably 50 cN or more.

[0070] Secondary Battery The present disclosure encompasses a secondary battery having the solid electrolyte medium. The secondary battery is not particularly limited as long as it includes the solid electrolyte medium, and other configurations, structures, etc., may be conventionally known. The secondary battery of the present disclosure is, for example, an all-solid-state battery containing a solid electrolyte containing the solid electrolyte medium and a metal salt between a positive electrode and a negative electrode. In the secondary battery of the present disclosure, metal ions are conducted between the positive electrode and the negative electrode via the solid electrolyte medium. The secondary battery of the present disclosure can be obtained by, for example, stacking a positive electrode, the solid electrolyte, and a negative electrode in a battery outer container (such as a laminate container), and sealing the battery outer container with a current extraction terminal connected to a current collector protruding outside the container.

[0071] In the secondary battery of the present disclosure, the solid electrolyte composition may be formed into a film and used as the solid electrolyte.

[0072] The present disclosure will be explained in more detail below using examples, but the technical scope of the present disclosure is not limited to these examples.

[0073] Description of raw materials Production of solid electrolyte medium (Production Examples 1 to 19 and Comparative Production Examples 1 to 3) PTME unit-containing polyol compounds (A1) PEPCD NT2002: polyether polycarbonate diol, average molecular weight 2000, PTME unit content 83.9 mass%, PTME unit polymerization degree n = 2.9, manufactured by Mitsubishi Chemical Corporation PEPCD NT2006: polyether polycarbonate diol, average molecular weight 2000, PTME unit content 94.7 mass%, PTME unit polymerization degree n = 8.8, manufactured by Mitsubishi Chemical Corporation PTMG2000: polytetramethylene ether glycol, average molecular weight 2000, PTME unit content 99.1 mass%, PTME unit polymerization degree n = 27.5, manufactured by Mitsubishi Chemical Corporation PTMG3000: Polytetramethylene ether glycol, average molecular weight 3000, PTME unit content 99.4 mass%, degree of polymerization of PTME units n = 41.4, manufactured by Mitsubishi Chemical Corporation. PTMG4000: Polytetramethylene ether glycol, average molecular weight 4000, PTME unit content 99.6 mass%, degree of polymerization of PTME units n = 55.3, manufactured by Mitsubishi Chemical Corporation.

[0074] Other polyol compounds (A2) PEG#2000: polyoxyethylene glycol, average molecular weight 2000, manufactured by Sanyo Chemical Industries, Ltd. Duranol (registered trademark) T6002: polyalkylene carbonate diol, average molecular weight 2000, manufactured by Asahi Kasei Chemicals Corporation TEGOMER D3403: methoxypolyethylene oxide trimethylolpropane ether, average molecular weight 1200, manufactured by Evonik Bis-MPA: dimethylolpropionic acid, manufactured by Perstorp 1,4-butanediol: manufactured by Mitsubishi Chemical Corporation Trimethylolpropane: manufactured by Perstorp Neopentyl glycol: manufactured by Mitsubishi Gas Chemical Company, Inc. Monool compounds (D) Uniox (registered trademark) M-2000: polyoxyethylene monomethyl ether, average molecular weight 2000, manufactured by NOF Corporation Unilube (registered trademark) 50MB-26: Polyoxyethylene polyoxypropylene butyl ether, average molecular weight 1800, manufactured by NOF Corporation 2-hydroxyethyl methacrylate: manufactured by Tokyo Chemical Industry Co., Ltd.

[0075] Polyisocyanate Compounds (B) Desmodur (registered trademark) W: methylenebis(1,4-cyclohexanediyl)bisisocyanate, manufactured by Covestro VESTANAT (registered trademark) IPDI: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, manufactured by Evonik Takenate (registered trademark) 500: xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc. Duranate (registered trademark) 50M, hexamethylene diisocyanate, manufactured by Asahi Kasei Chemicals Corporation Millionate (registered trademark) MT: diphenylmethane diisocyanate, manufactured by Tosoh Corporation

[0076] Chain extender: Ethylenediamine: manufactured by Tokyo Chemical Industry Co., Ltd. Diethylenetriamine: manufactured by Tokyo Chemical Industry Co., Ltd.

[0077] Neutralizing agent: Diisopropylethylamine: manufactured by Koei Chemical Co., Ltd. Triethylamine: manufactured by Tokyo Chemical Industry Co., Ltd. Lithium hydroxide monohydrate: manufactured by Tokyo Chemical Industry Co., Ltd.

[0078] Catalyst Neostan (registered trademark) U-600: bismuth-based catalyst, manufactured by Nitto Kasei Co., Ltd.

[0079] Preparation of solid electrolytes (Examples 1 to 22 and Comparative Examples 1 to 4) Metal salts LiTFSI: lithium bis(trifluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd. NaTFSI: sodium bis(trifluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd. Solid electrolyte media Water-dispersible polyurethane resins or solvent-based polyurethane resins of Production Examples 1 to 19, water-dispersible polyurethane resins of Comparative Production Examples 2 to 3 ALKOX (registered trademark) L-11: polyethylene oxide, manufactured by Meisei Chemical Industry Co., Ltd.

[0080] Production Examples of Solid Electrolyte Medium Production Example 1 A separable flask equipped with a stirrer, a condenser, and a thermometer was charged with 16.5 parts by mass of Desmodur (registered trademark) W and 14.0 parts by mass of VESTANAT (registered trademark) IPDI as the polyisocyanate compound (B), 61.3 parts by mass of PTMG2000 (average molecular weight 2000) as the PTME unit-containing polyol compound (A1), 0.8 parts by mass of neopentyl glycol and 7.3 parts by mass of Bis-MPA as other polyol compounds (A2), 6.7 parts by mass of diisopropylethylamine as a neutralizing agent, and 103.5 parts by mass of methyl ethyl ketone as an organic solvent, and mixed at room temperature. Next, the liquid temperature was raised to 70°C, and 0.07 parts by mass of Neostan U-600 catalyst was added. The reaction was continued until the isocyanate group concentration (content) of the reaction liquid, measured in accordance with Method A of JIS K 1603-1:2007, reached 2.60%. After the liquid temperature was cooled to 30°C, 181 parts by mass of ion-exchanged water was added dropwise under strong stirring to disperse the mixture. To the resulting dispersion, an aqueous solution in which 0.03 parts by mass of ethylenediamine and 1.1 parts by mass of diethylenetriamine, as chain extenders, were dissolved in 71.0 parts by mass of ion-exchanged water, was added, and the mixture was allowed to react for 1 hour at a liquid temperature of 50°C. Thereafter, methyl ethyl ketone was distilled off under reduced pressure, and ion-exchanged water was added to obtain a water-dispersible polyurethane resin with a solids content of 30%.

[0081] Production Examples 2 to 17 and Comparative Production Examples 1 to 3 Water-dispersible polyurethane resins were obtained using the compositions and contents shown in Table 1 by the method described in Production Example 1. In Comparative Production Example 1, however, no polyurethane resin could be produced.

[0082] Production Example 18: A separable flask equipped with a stirrer, a condenser, and a thermometer was charged with 12.5 parts by mass of Millionate (registered trademark) MT as the polyisocyanate compound (B), 60.0 parts by mass of PTMG2000 (average molecular weight 2000) as the PTME unit-containing polyol compound (A1), and 108.0 parts by mass of N,N-dimethylacetamide as an organic solvent, and mixed at room temperature. The reaction was continued until the isocyanate group concentration (content) of the reaction solution measured in accordance with Method A of JIS K 1603-1:2007 reached 1.80%. To this was added a solution of 0.90 parts by mass of 1,4-butanediol dissolved in 185.0 parts by mass of N,N-dimethylacetamide as another polyol compound (A2), and the mixture was allowed to react at a liquid temperature of 30 ° C. for 1 hour. Thereafter, the reaction was continued until the concentration of isocyanate groups reached 0.00%, and N,N-dimethylacetamide was added to obtain a solvent-based polyurethane resin with a solid content of 20%.

[0083] Production Example 19 A solvent-based polyurethane resin was obtained using the composition and contents shown in Table 1 by the method described in Production Example 18.

[0084]

[0085] Example: Solid Electrolyte Example 1 Using Lithium Salt A solid electrolyte composition was produced by mixing the water-dispersible polyurethane resin obtained in Production Example 1 and a metal salt (LiTFSI) so that the metal salt (LiTFSI) in the solid electrolyte was present in the proportion shown in Table 2. The resulting solid electrolyte composition was dried at 50°C for 24 hours and then at 110°C for 1 hour to produce a solid electrolyte. The ionic conductivity and puncture strength of the resulting solid electrolyte were measured by the following methods.

[0086] Ion conductivity measurement The ionic conductivity of the obtained solid electrolyte was measured using an impedance measurement device. Film preparation conditions: 50°C x 24 hours + 110°C x 1 hour Test sample: φ5.0 mm x 0.39 mm Measurement temperature: 24°C Measuring equipment: Hokuto Denko HZ-5000 HAG3001 Measurement conditions: 10 mV, 10 Hz to 0.1 MHz

[0087] Film piercing test The obtained solid electrolyte (film thickness 30 μm) was measured for the value of the scale (average value of 3 tests) at the moment when the film was pierced using a rod-type tension gauge with a needle (manufactured by Nakamura Seisakusho, model number TK10000CN-G). Test surface: φ16 mm, piercing rod diameter: φ3 mm

[0088] Examples 2 to 19 The water-dispersible polyurethane resins or solvent-based polyurethane resins obtained in Production Examples 2 to 19 were mixed with a metal salt (LiTFSI) so that the metal salt (LiTFSI) content in the solid electrolyte was as shown in Table 2, and solid electrolyte compositions were produced in the same manner as in Example 1. Each solid electrolyte was then dried in the same manner as in Example 1. The ionic conductivity and puncture strength of each of the obtained solid electrolytes were measured.

[0089] Comparative Example 1 The water-dispersible polyurethane resin obtained in Comparative Production Example 2 and a metal salt (LiTFSI) were mixed so that the metal salt (LiTFSI) content in the solid electrolyte was as shown in Table 2, and a solid electrolyte composition was produced in the same manner as in Example 1. The solid electrolyte was then dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0090] Comparative Example 2 The water-dispersible polyurethane resin obtained in Comparative Production Example 3 and a metal salt (LiTFSI) were mixed so that the metal salt (LiTFSI) in the solid electrolyte was in a ratio shown in Table 2, and a solid electrolyte composition was produced in the same manner as in Example 1. The solid electrolyte was dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0091] Comparative Example 3 A solid electrolyte composition was obtained by using polyethylene oxide (ALKOX (registered trademark) L-11) instead of the water-dispersible polyurethane resin and dissolving it in water so that the metal salt (LiTFSI) in the solid electrolyte was in the proportion shown in Table 2. Drying was carried out in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0092]

[0093] Example: Solid Electrolyte Using Sodium Salt Example 20 The water-dispersible polyurethane resin obtained in Production Example 5 and a metal salt (NaTFSI) were mixed so that the metal salt (NaTFSI) in the solid electrolyte had a ratio shown in Table 3, and a solid electrolyte composition was produced in the same manner as in Example 1. The solid electrolyte was dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0094] Comparative Example 4 The water-dispersible polyurethane resin obtained in Comparative Production Example 3 and a metal salt (NaTFSI) were mixed so that the metal salt (NaTFSI) in the solid electrolyte was in a ratio shown in Table 3, and a solid electrolyte composition was produced in the same manner as in Example 1. The solid electrolyte was dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0095]

[0096] Example: Solid Electrolyte Containing High Concentration of Metal Salt Example 21 The water-dispersible polyurethane resin obtained in Production Example 5 and a metal salt (LiTFSI) were mixed so that the metal salt (LiTFSI) in the solid electrolyte had a ratio shown in Table 4, and a solid electrolyte composition was produced in the same manner as in Example 1. The solid electrolyte was dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0097] Example 22 The water-dispersible polyurethane resin obtained in Production Example 5 and a metal salt (NaTFSI) were mixed so that the metal salt (NaTFSI) in the solid electrolyte was in a ratio shown in Table 4, and a solid electrolyte composition was produced in the same manner as in Example 1, and the solid electrolyte was dried in the same manner as in Example 1 to produce a solid electrolyte. The ionic conductivity and puncture strength of the obtained solid electrolyte were measured.

[0098]

[0099] The solid electrolyte medium and secondary batteries using the same disclosed herein are useful for mobile phones, personal computers, hybrid vehicles, and electric vehicles. This application claims priority from Japanese Patent Application No. 2023-205957, filed December 6, 2023. Japanese Patent Application No. 2023-205957 is incorporated herein by reference.

Claims

1. a structure derived from the polyol compound (A); A structure derived from the polyisocyanate compound (B), A solid electrolyte medium constituting a solid electrolyte of an all-solid-state battery, comprising a polyurethane resin (U) containing: The polyol compound (A) contains polytetramethylene ether glycol (A1), The content of polytetramethylene ether glycol (A1) in the polyol compound (A) is 70% by mass or more and 99.9% by mass or less. The solid electrolyte medium.

2. A solid electrolyte medium as described in claim 1, wherein the polyisocyanate compound (B) includes an alicyclic diisocyanate.

3. The solid electrolyte medium described in claim 1, wherein the polyol compound (A) further contains a polyol compound (A2) other than a polyol compound having a structural unit represented by formula (1). 【Chemistry 1】 (In the formula, n is an integer of 2 or more.)

4. A solid electrolyte medium as described in claim 1, wherein the polyurethane resin (U) further contains a structure derived from a chain extender.

5. a solid electrolyte medium containing a polyurethane resin (U) having a structure derived from a polyol compound (A) and a structure derived from a polyisocyanate compound (B); A metal salt (C) A solid electrolyte composition for an all-solid-state battery, comprising: The polyol compound (A) contains polytetramethylene ether glycol (A1), The content of polytetramethylene ether glycol (A1) in the polyol compound (A) is 70% by mass or more and 99.9% by mass or less. The solid electrolyte composition.

6. 6. The solid electrolyte composition according to claim 5, wherein a weight ratio of the polyurethane resin (U) to the metal salt (C) in the solid electrolyte composition is polyurethane resin / metal salt=20 / 80 to 95 / 5.

7. The solid electrolyte composition according to claim 5 , wherein the metal salt (C) is an alkali metal salt.

8. The solid electrolyte composition according to claim 5 , wherein the metal salt (C) is a lithium salt.

9. A secondary battery comprising the solid electrolyte medium according to claim 1.

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