Solid electrolyte, method for producing the same, battery, and flexible device

Abstract

Provided are: a solid electrolyte which has excellent toughness as well as excellent ion conductivity and cation transport number; a battery comprising a solid electrolyte; and a flexible device comprising a battery. The solid electrolyte contains: a reaction product of a polyol having a specific structure with a polyisocyanate; and a metal salt.

Description

Solid electrolytes, batteries and flexible devices

[0001] The present invention relates to a solid electrolyte, a battery including the solid electrolyte, and a flexible device including the battery.

[0002] Batteries for wearable devices and implantable devices are required to have high safety and durability (toughness) against bending, etc., in addition to battery performance. Solid-state batteries are becoming mainstream for use in such devices because they do not use organic solvents and are safe with no risk of leakage. Polyethylene glycol (PEG)-based polymers (see Non-Patent Document 1) and polycarbonate-based polymers (see Patent Documents 1 and 2) have been investigated as conventional solid-state electronic electrolytes.

[0003] Wright, British Polymer Journal, UK, 1975, No. 7, p. 319

[0004] Japanese Patent Application Laid-Open No. 8-217868 International Publication No. 2017 / 033805

[0005] However, PEG-based polymers have the problems of high flexibility but poor toughness and low cation transference numbers. Polyethylene carbonate-based polymers have high cation transference numbers and ionic conductivity but lack flexibility and toughness. Furthermore, ionic conductivity is generally high above the Tg of the polymer used in solid electrolytes but decreases below the Tg, making it difficult to obtain stable ionic conductivity over a wider temperature range.

[0006] The present invention is intended to solve these problems, and aims to provide a solid electrolyte that is excellent in toughness as well as in ionic conductivity and cation transference number, a battery including the solid electrolyte, and a flexible device including the battery.

[0007] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a solid electrolyte containing a reaction product of a polyol having a specific structure and a polyisocyanate can solve the above-mentioned problems, and have completed the present invention. That is, the present invention is as follows: [1] A solid electrolyte containing a reaction product of a polyol having a structure represented by the following general formula (1) and a polyisocyanate, and a metal salt:

[0008] (Wherein A is -(R １ O) ａ C(=O)O-, B is -R ２ O-, n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms; and a is a number from 1 to 30. When a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block form or random form. When a plurality of A's are present, the plurality of A's may be the same or different. When a plurality of B's ​​are present, the plurality of B's ​​may be the same or different. A, B and R ３ The bonding order of the above is not important. A plurality of As and a plurality of Bs may be bonded in a block form or randomly.) [2] The solid electrolyte according to the above [1], wherein in the general formula (1), the proportion of A to the total of A and B is 3 to 100 mass%. [3] The solid electrolyte according to the above [1] or [2], wherein B in the general formula (1) contains at least one selected from the group consisting of an oxyethylene group and an oxypropylene group. [4] The solid electrolyte according to the above [3], wherein the proportion of the oxyethylene group contained in B in the general formula (1) is 25 to 100 mass% and the proportion of the oxypropylene group is 0 to 75 mass%. [5] The solid electrolyte according to any of the above [1] to [4], wherein the number average molecular weight of the polyol is 500 to 15,000. [6] The solid electrolyte according to any of the above [1] to [5], wherein the polyol is a diol having a structure represented by the following general formula (2):

[0009] (wherein n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms; and a is a number from 1 to 30. When a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block or random manner. １ O) ａ When there are multiple structures represented by "C(=O)O-", multiple "-(R １ O) ａ The structures represented by "-(R ２ When there are multiple structures represented by "-(R ２ The structures represented by "-(R １ O) ａ C(=O)O-" structure, "-(R ２ O)-" and R ３ The order of bonding does not matter. １ O) ａ C(=O)O-" and a plurality of "-(R ２The structure represented by "O)-" may be bonded in a block form or random form.) [7] The solid electrolyte according to any one of the above [1] to [6], wherein the number average molecular weight of the reaction product is 20,000 to 150,000. [8] The solid electrolyte according to any one of the above [1] to [7], wherein the amount of carbonate groups per molecule of the reaction product is 3 to 70 mass%. [9] The solid electrolyte according to any one of the above [1] to [8], wherein the polyisocyanate is a diisocyanate.

[10] The solid electrolyte according to any one of the above [1] to [9], wherein the metal salt is at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts.

[11] The solid electrolyte according to any one of the above [1] to

[10] , further comprising a plasticizer.

[12] The solid electrolyte according to any one of the above [1] to

[11] , further comprising a filler.

[13] A method for producing a solid electrolyte comprising a reaction product of a diol represented by the following general formula (2) and a polyisocyanate, and a metal salt:

[0010] (wherein n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms; and a is a number from 1 to 30. When a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block or random manner. １ O) ａ When there are multiple structures represented by "C(=O)O-", multiple "-(R １ O) ａ The structures represented by "-(R ２ When there are multiple structures represented by "-(R ２ The structures represented by "-(R １ O) ａ C(=O)O-" structure, "-(R ２ O)-" and R ３The order of bonding does not matter. １ O) ａ C(=O)O-" and a plurality of "-(R ２ The structure represented by "(O)-" may be bonded in a block form or randomly.)

[14] A method for producing a solid electrolyte according to the above

[13] , wherein the diol is a polyoxyalkylene polycarbonate diol obtained by ring-opening addition polymerization of a cyclic ether in the presence of a ring-opening polymerization catalyst using a polycarbonate diol or a polyether polycarbonate diol as an initiator.

[15] A method for producing a solid electrolyte according to the above

[14] , wherein the cyclic ether contains at least one selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide.

[16] A method for producing a solid electrolyte according to the above

[14] or

[15] , wherein the cyclic ether contains ethylene oxide and propylene oxide, and the proportion of ethylene oxide in the total of ethylene oxide and propylene oxide in the polyoxyalkylene polycarbonate diol is 25 to 100 mass%.

[17] A battery comprising the solid electrolyte according to any of the above [1] to

[12] .

[18] A flexible device comprising the battery according to

[17] above.

[0011] According to the present invention, it is possible to provide a solid electrolyte that is excellent in toughness, ionic conductivity, and cation transport number, a battery including the solid electrolyte, and a flexible device including the battery.

[0012] The present invention will be described in detail below. In this specification, any of the preferred values ​​may be arbitrarily adopted, and combinations of preferred values ​​are considered more preferable. Furthermore, in this specification, the term "XX to YY" means "XX or more and YY or less." Furthermore, in this specification, the lower and upper limits of preferred numerical ranges (e.g., ranges of content, etc.) described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to obtain "10 to 60." Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the Examples. Furthermore, in this specification, the "unit" constituting a polymer refers to an atomic group formed by polymerization of a monomer. Furthermore, in this specification, the number average molecular weight (hereinafter sometimes referred to as "Mn") of the reaction product is the polystyrene-equivalent molecular weight measured using gel permeation chromatography (GPC) according to the method described in the Examples, using a calibration curve prepared using standard polystyrene samples with known molecular weights. The Mn and weight average molecular weight (hereinafter sometimes referred to as "Mw") of the polyol are polypropylene glycol-equivalent molecular weights measured by gel permeation chromatography (GPC) using the method described in the Examples, with a calibration curve prepared using standard polypropylene glycol samples with known hydroxyl value-equivalent molecular weights. In this specification, the molecular weight distribution is a value calculated from the above Mw and Mn, and is the ratio of Mw to Mn (hereinafter sometimes referred to as "Mw / Mn").

[0013] [Solid Electrolyte] The solid electrolyte of the present invention contains a reaction product of a polyol having a structure represented by the following general formula (1) with a polyisocyanate, and a metal salt.

[0014]

[0015] In the above general formula (1), A is -(R １ O) ａ C(=O)O-, B is -R ２O-, n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms; and a is a number from 1 to 30. When a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block form or random form. When a plurality of A's are present, the plurality of A's may be the same or different. When a plurality of B's ​​are present, the plurality of B's ​​may be the same or different. A, B and R ３ The bonding order of the above is not important. A plurality of A's and B's may be bonded in a block form or random form.

[0016] (Reaction Product) The reaction product of a polyol having the structure shown in the general formula (1) with a polyisocyanate has a soft segment having a carbonate chain and a hard segment having a urethane bond. It is believed that the soft segment easily localizes cations such as Li ions, thereby improving the ionic conductivity and cation transport number of the solid electrolyte. It is also believed that the hard segment contributes to the toughness of the solid electrolyte and the maintenance of ionic conductivity during deformation by maintaining the layer structure of the polymer through hydrogen bonding or the like. The cation transport number refers to the proportion of ionic conductivity due to cations in the total ionic conductivity. Furthermore, toughness is a property that combines excellent strength and excellent toughness, and also provides excellent elongation.

[0017] [Polyol] The polyol has a structure represented by the following general formula (1).

[0018]

[0019] In the above general formula (1), A is -(R １ O) ａ C(=O)O-, B is -R ２ O-, n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms; and a is a number from 1 to 30. When a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block form or random form. When a plurality of A's are present, the plurality of A's may be the same or different. When a plurality of B's ​​are present, the plurality of B's ​​may be the same or different. A, B and R ３ The bonding order of the above is not important. A plurality of A's and B's may be bonded in a block form or random form.

[0020] The above R １ From the viewpoint of obtaining a solid electrolyte having superior toughness, the divalent hydrocarbon group having 2 to 10 carbon atoms as the alkylene group is preferably a linear or branched alkylene group having 4 to 6 carbon atoms, more preferably an n-butylene group (having 4 carbon atoms) or a 2-methylbutylene group (having 5 carbon atoms), and even more preferably an n-butylene group.

[0021] The above R ２ From the viewpoint of obtaining a solid electrolyte having superior toughness, the divalent hydrocarbon group having 2 to 10 carbon atoms as the alkyl group is preferably a linear or branched alkylene group having 2 to 6 carbon atoms, more preferably an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, or a 2-methylbutylene group, and even more preferably an ethylene group, an isopropylene group, or an n-butylene group.

[0022] The above R ３ From the viewpoint of obtaining a solid electrolyte having superior toughness, the divalent hydrocarbon group having 2 to 10 carbon atoms as the alkylene group is preferably a linear or branched alkylene group having 4 to 6 carbon atoms, more preferably an n-butylene group or a 2-methylbutylene group, and even more preferably an n-butylene group.

[0023] The above n is not particularly limited as long as it is a number from 1 to 170, but is preferably a number from 1 to 150, more preferably a number from 2 to 100, and even more preferably a number from 2 to 50. When n is equal to or greater than the above lower limit, a solid electrolyte having excellent toughness and a cation transport number can be obtained, and when n is equal to or less than the above upper limit, the flexibility of the solid electrolyte can be easily adjusted within a good range.

[0024] The above m is not particularly limited as long as it is a number from 0 to 170, but is preferably a number from 0 to 150, more preferably a number from 0 to 100, and even more preferably a number from 0 to 50. When m is equal to or greater than the above lower limit, a solid electrolyte having superior ionic conductivity and flexibility can be obtained, and when m is equal to or less than the above upper limit, the solid electrolyte has superior toughness.

[0025] The above-mentioned "a" is not particularly limited as long as it is a number from 1 to 30, but is preferably a number from 1 to 25, more preferably a number from 2 to 20, and even more preferably a number from 2 to 18. When "a" is equal to or greater than the above-mentioned lower limit, a solid electrolyte having more excellent ionic conductivity and flexibility can be obtained, and when "a" is equal to or less than the above-mentioned upper limit, the flexibility of the solid electrolyte can be easily adjusted within a good range.

[0026] When the above a is 2 or more, a plurality of (R １ O) may be the same or different. １ O) may be bonded in a block form or randomly, but from the viewpoint of obtaining a solid electrolyte having superior ionic conductivity, they are preferably bonded in a random form.

[0027] When there are a plurality of A's, the A's may be the same or different. When there are a plurality of B's, the B's may be the same or different. ３ The bonding order of the A's and the B's is not important. The A's and the B's may be bonded in a block form or randomly, but are preferably bonded in a block form from the viewpoint of obtaining a solid electrolyte having superior ionic conductivity.

[0028] In the general formula (1), the proportion of A relative to the total of A and B is preferably 3 to 100 mass%, more preferably 10 to 98 mass%, and even more preferably 15 to 97 mass%. When the proportion of A is equal to or greater than the lower limit, the solid electrolyte becomes stronger and the cation transference number becomes better. When the proportion of A is equal to or less than the upper limit, the solid electrolyte becomes more flexible and has higher ionic conductivity.

[0029] In order to improve the ionic conductivity and cation transference number in the solid electrolyte, B in the above general formula (1) preferably contains at least one selected from the group consisting of an oxyethylene group and an oxypropylene group.

[0030] The proportion of the oxyethylene groups contained in B in the general formula (1) is preferably 25 to 100 mass %, more preferably 30 to 95 mass %, and even more preferably 30 to 90 mass %, from the viewpoint of improving the ionic conductivity of the solid electrolyte. １ It is calculated by determining the monomer composition of the oxyalkylene chain using H-NMR. Specifically, it can be measured by the method described in the examples.

[0031] The proportion of the oxypropylene groups contained in B in the general formula (1) is preferably 0 to 75 mass %, more preferably 5 to 70 mass %, and even more preferably 10 to 65 mass %, from the viewpoint of improving the ionic conductivity and flexibility of the solid electrolyte. １ It is calculated by determining the monomer composition of the oxyalkylene chain using H-NMR. Specifically, it can be measured by the method described in the examples.

[0032] The number-average molecular weight (Mn) of the polyol is preferably 500 to 15,000, more preferably 800 to 14,000, and even more preferably 1,000 to 12,000. When the number-average molecular weight of the polyol is equal to or greater than the lower limit, the flexibility of the reaction product obtained using the polyol is improved, and the ionic conductivity and cation transport number of the solid electrolyte are improved. When the number-average molecular weight is equal to or less than the upper limit, the toughness of the reaction product obtained using the polyol is improved.

[0033] The Mw / Mn of the polyol is not particularly limited, but is preferably 3.0 or less, more preferably 1.01 to 2.5, and even more preferably 1.02 to 2.0. When the Mw / Mn of the polyol is equal to or greater than the lower limit, the flexibility and toughness of the reaction product obtained using the polyol are improved, and the ionic conductivity and cation transport number of the solid electrolyte are improved. When the Mw / Mn is equal to or less than the upper limit, the polyol tends to have a low viscosity and is easy to handle.

[0034] The polyol is not particularly limited as long as it has the structure represented by the general formula (1) above. However, from the viewpoint of improving the ionic conductivity and cation transport number of the solid electrolyte, a diol represented by the following general formula (2) is preferred.

[0035]

[0036] In the above general formula (2), R １ , R ２ , R ３ , a, m, and n are the R １ , R ２ , R ３ In the above general formula (2), when a is 2 or more, a plurality of (R １ O) may be the same or different. １ The structure represented by "-(R O)" may be bonded in a block form or in a random form. １ O) ａ When there are multiple structures represented by "C(=O)O-", multiple "-(R １ O)ａ The structures represented by "-(R ２ When there are multiple structures represented by "-(R ２ The structures represented by "-(R １ O) ａ C(=O)O-" structure, "-(R ２ O)-" and R ３ The order of bonding does not matter. １ O) ａ C(=O)O-" and a plurality of "-(R ２ The structure represented by "(O)-" may be bonded in a block form or random form.

[0037] The diol represented by the general formula (2) may be a polycarbonate diol, a polyether polycarbonate diol, or a polyoxyalkylene polycarbonate diol. Polyoxyalkylene polycarbonate diol is preferred because of its excellent toughness.

[0038] Examples of polycarbonate diols include T6002 (product name of Asahi Kasei Corporation, solid, Mn: 2,100, R １ and R ３ : hexamethylene group, a: 1, n: 18, m: 0), Nipporan 981 (product name of Tosoh Corporation, solid, Mn: 1,000, R １ and R ３ : hexamethylene group, a: 1, n: 6, m: 0), Nipporan 982R (product name of Tosoh Corporation, solid, Mn: 2,000, R １ and R ３ : hexamethylene group, a: 1, n: 13, m: 0), T5651 (product name of Asahi Kasei Corporation, solid, Mn: 1,000, R １ and R ３ : hexamethylene group and pentamethylene group, a: 1, n: 7, m: 0), T5652 (product name of Asahi Kasei Corporation, solid, Mn: 2,000, R １ and R ３: hexamethylene group and pentamethylene group, a: 1, n: 14, m: 0), PH50 (Ube Industries product name, solid, Mn: 500, R １ and R ３ : hexamethylene group and pentamethylene group, a: 1, n: 2.5, m: 0), NL1005B (Mitsubishi Chemical product name, solid, Mn: 1,000, R １ and R ３ : butylene group and neopentane group, a: 1, n: 2.5, m: 0) can also be used.

[0039] Examples of polyether polycarbonate diols include NT1002 (trade name of Mitsubishi Chemical Corporation, transparent viscous liquid, Mn: 1,000, glass transition temperature: −78° C., R １ , R ２ and R ３ : n-butylene group, a: 3.2, n: 2.7, m: 3.2), NT2002 (Mitsubishi Chemical Corporation product name, transparent viscous liquid, Mn: 2,000, glass transition temperature: -71°C, R １ , R ２ and R ３ : n-butylene group, a: 3.2, n: 6.3, m: 3.2), NT2006 (Mitsubishi Chemical Corporation product name, transparent viscous liquid, Mn: 2,000, glass transition temperature: -84°C, R １ , R ２ and R ３ : n-butylene group, a: 8.8, n: 2.0, m: 8.8) can also be used.

[0040] The polyoxyalkylene polycarbonate diol has a polyoxyalkylene chain composed of oxyalkylene units, a carbonate group, and a terminal hydroxyl group. The polyoxyalkylene polycarbonate diol can be obtained, for example, by using the above-mentioned polycarbonate diol or polyether polycarbonate diol as an initiator and subjecting a cyclic ether to ring-opening addition polymerization with the hydroxyl groups (active hydrogen-containing groups) of the polycarbonate diol or polyether polycarbonate diol in the presence of a ring-opening polymerization catalyst.

[0041] Examples of cyclic ethers include ethylene oxide (hereinafter sometimes referred to as "EO"), propylene oxide (hereinafter sometimes referred to as "PO"), 1,2-butylene oxide, and 2,3-butylene oxide. These may be used alone or in combination of two or more. Among these, at least one selected from EO and PO is preferred from the viewpoints of ease of reaction with polycarbonate diol or polyether polycarbonate diol and improving the ionic conductivity and flexibility of the solid electrolyte. When both EO and PO are used as cyclic ethers, the proportion of EO in the total of EO and PO in the polyoxyalkylene polycarbonate diol is preferably 25 to 100 mass%, more preferably 30 to 95 mass%, and even more preferably 30 to 90 mass%, from the viewpoint of improving the ionic conductivity of the solid electrolyte. The proportion of PO in the total of EO and PO in the polyoxyalkylene polycarbonate diol is preferably 0 to 75 mass%, more preferably 5 to 70 mass%, and even more preferably 10 to 65 mass%, from the viewpoint of improving the ionic conductivity of the solid electrolyte.

[0042] The ring-opening addition polymerization in the case where two or more types of cyclic ethers are reacted with a polycarbonate diol or a polyether polycarbonate diol may be random polymerization, block polymerization, or a combination of random polymerization and block polymerization.

[0043] The polymerization temperature for the ring-opening polymerization reaction of the cyclic ether is not particularly limited, but is preferably 30 to 180° C., more preferably 70 to 160° C., and even more preferably 90 to 140° C. When the polymerization temperature is equal to or higher than the above lower limit, the ring-opening polymerization of the cyclic ether can be reliably initiated, and when the polymerization temperature is equal to or lower than the above upper limit, a decrease in the polymerization activity of the ring-opening polymerization catalyst can be suppressed.

[0044] The polymerization time for the ring-opening polymerization reaction of the cyclic ether is not particularly limited, but is preferably 2 to 18 hours, more preferably 3 to 14 hours, and even more preferably 4 to 10 hours. When the polymerization time is equal to or greater than the above lower limit, the reaction proceeds well, and when it is equal to or less than the above upper limit, the reaction is economically efficient.

[0045] The amount of the cyclic ether to be charged is not particularly limited, but is preferably 25 to 1,500 parts by mass, more preferably 50 to 1,200 parts by mass, and even more preferably 100 to 700 parts by mass, relative to 100 parts by mass of the polyether polycarbonate diol (PEPCD). When the amount of the cyclic ether to be charged is within the above-mentioned preferred range, the flexibility and toughness of the reaction product obtained using the cyclic ether can be further improved. In addition, the ionic conductivity and cation transport number of the solid electrolyte can be further improved.

[0046] The ring-opening polymerization reaction of the cyclic ether is preferably carried out under good stirring conditions. When using a stirring method using a general stirring blade, it is preferable to make the rotation speed of the stirring blade as fast as possible within a range in which a large amount of gas from the gas phase is not taken into the reaction liquid and the stirring efficiency is not reduced. In addition, from the viewpoint of narrowing the Mw / Mn of the obtained polymer, it is preferable to make the supply rate of the cyclic ether into the reaction vessel as slow as possible, but since this reduces the production efficiency, it is preferable to determine the supply rate of the cyclic ether by comparing and balancing these factors.

[0047] A reaction solvent may be used in the ring-opening polymerization reaction of a cyclic ether. The reaction solvent is not particularly limited, and examples thereof include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated solvents such as chloroform and dichloromethane; and ethers such as tetrahydrofuran and dioxane. These may be used alone or in combination of two or more. Among these, hexane and tetrahydrofuran are preferred from the viewpoint of their low boiling point and ease of removal after the reaction is completed. The amount of the reaction solvent used is not particularly limited, and a desired amount can be used.

[0048] The ring-opening addition polymerization catalyst is not particularly limited, and suitable examples include composite metal cyanide complex catalysts (hereinafter sometimes referred to as "DMC catalysts"); alkali catalysts such as sodium hydroxide, potassium hydroxide, and cesium hydroxide; Ziegler-Natta catalysts composed of organoaluminum compounds and transition metal compounds; metal porphyrin catalysts as complexes obtained by reacting porphyrin; phosphazene catalysts; imino group-containing phosphazenium salts; tris(pentafluorophenyl)borane; catalysts composed of metal salen complexes; and catalysts composed of reduced Robson's type macrocyclic ligands. These may be used alone or in combination of two or more. When a DMC catalyst is used as the ring-opening addition polymerization catalyst, a polyoxyalkylene polycarbonate diol having a narrow Mw / Mn and a lower viscosity can be obtained. The DMC catalyst is not particularly limited, and examples thereof include a zinc hexacyanocobaltate complex in which the ligand is t-butyl alcohol (hereinafter sometimes referred to as a "TBA-DMC catalyst"), a zinc hexacyanocobaltate complex in which the ligand is ethylene glycol dimethyl ether (sometimes referred to as a "glyme"), and a zinc hexacyanocobaltate complex in which the ligand is diethylene glycol dimethyl ether (sometimes referred to as a "diglyme"). These may be used alone or in combination of two or more. Among these, TBA-DMC catalysts are preferred from the viewpoints of higher activity during polymerization, the ability to narrow the Mw / Mn of the polyoxyalkylene polycarbonate diol, and the ability to achieve lower viscosity.

[0049] The amount of ring-opening addition polymerization catalyst added is not particularly limited as long as it is the amount necessary for the ring-opening polymerization of the cyclic ether, but is preferably as small as possible, and is preferably 0.003 to 0.03 parts by mass, more preferably 0.004 to 0.025 parts by mass, and even more preferably 0.005 to 0.02 parts by mass per 100 parts by mass of the polyoxyalkylene polycarbonate diol. The smaller the amount of ring-opening addition polymerization catalyst added in the ring-opening polymerization reaction of the cyclic ether, the smaller the amount of ring-opening addition polymerization catalyst contained in the product polyoxyalkylene polycarbonate diol. This reduces the effect of the ring-opening addition polymerization catalyst on the reactivity of the polyoxyalkylene polycarbonate diol with the polyisocyanate and also reduces costs.

[0050] For ring-opening addition polymerization using a ring-opening addition polymerization catalyst, for example, WO 2003 / 062301, WO 2004 / 067633, JP 2004-269776 A, JP 2005-15786 A, WO 2013 / 065802, JP 2015-010162 A can be used.

[0051] [Polyisocyanate] The polyisocyanate is not particularly limited as long as it is a compound having a plurality of isocyanate groups in one molecule. However, a diisocyanate is preferred from the viewpoints that the flexibility of the reaction product obtained by using the polyisocyanate is improved and the ionic conductivity and cation transport number of the solid electrolyte are improved. Examples of diisocyanates include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate (hereinafter sometimes referred to as "MDI"), naphthalene-1,5-diisocyanate, polyphenylene polymethylene diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate; aralkyl diisocyanates such as tetramethylxylylene diisocyanate and xylylene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate and 4,4'-methylenebis(cyclohexyl isocyanate); urethane-modified products obtained from diisocyanates; biuret-modified products obtained from diisocyanates; allophanate-modified products obtained from diisocyanates; carbodiimide-modified products obtained from diisocyanates; and isocyanurate-modified products obtained from diisocyanates. These may be used alone or in combination of two or more. Among these, from the viewpoint of reactivity with polyol, aromatic diisocyanates are preferred, and 4,4'-diphenylmethane diisocyanate is more preferred, and from the viewpoint of easy suppression of yellowing over time, aliphatic diisocyanates and alicyclic diisocyanates are preferred, and hexamethylene diisocyanate and isophorone diisocyanate are more preferred.

[0052] The isocyanate group index, which is the ratio of isocyanate groups in the polyisocyanate to the hydroxyl groups in the polyol ((the number of isocyanate groups contained in the polyisocyanate) / (the number of hydroxyl groups contained in the polyol)×100), is not particularly limited, but is preferably 150 to 300, and more preferably 180 to 280.

[0053] The molecular weight of the polyisocyanate is not particularly limited, but is preferably 120 to 400, more preferably 130 to 390, and even more preferably 140 to 380. When the molecular weight of the polyisocyanate is within the above range, the toughness of the reaction product obtained using the polyisocyanate is improved.

[0054] From the viewpoint of flexibility and toughness of the reaction product, it is preferable that the reaction product further contains a structural unit derived from a chain extender. The chain extender is preferably at least one selected from the group consisting of polyols (excluding polyols having the structure represented by general formula (1)) and polyamines, and has at least two active hydrogens that react with isocyanate groups.

[0055] Specific examples of the chain extender are not particularly limited, and include, for example, straight-chain diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2,4-heptanediol; Branched chain diols such as 1,4-dimethylolhexane, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, dimer diol, and neopentyl glycol; ether group-containing diols such as diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol; 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4 diols having an alicyclic structure such as 1,4-dihydroxycyclohexane and 1,4-dihydroxyethylcyclohexane; diols having an aromatic group such as xylylene glycol, 1,4-dihydroxyethylbenzene and 4,4'-methylenebis(hydroxyethylbenzene); polyols such as glycerin, trimethylolpropane and pentaerythritol; hydroxyamines such as N-methylethanolamine and N-ethylethanolamine; ethylenediamine, 1,3-diaminopropane, hexamethylenediamine, triethylenetetramine, diethylenetriamine Examples of the polyamines include amine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, 4,4'-diphenylmethanediamine, methylenebis(o-chloroaniline), xylylenediamine, diphenyldiamine, tolylenediamine, hydrazine, piperazine, and N,N'-diaminopiperazine.These may be used alone or in combination of two or more.

[0056] Among these, ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol are preferred, and 1,4-butanediol is more preferred, in that the reaction product has better flexibility and is industrially available in large quantities at low cost.

[0057] The molecular weight of the chain extender is not particularly limited, but is preferably 60 to 1,000, and more preferably 60 or more and less than 300. When the molecular weight of the chain extender is within the above range, the flexibility and toughness of the reaction product can be further improved. In addition, the ionic conductivity and cation transport number of the solid electrolyte can be further improved.

[0058] The number-average molecular weight (Mn) of the reaction product is preferably 20,000 to 150,000, more preferably 25,000 to 120,000, and even more preferably 30,000 to 100,000. When the number-average molecular weight of the reaction product is equal to or greater than the lower limit, the toughness of the solid electrolyte tends to be improved, while when it is equal to or less than the upper limit, the flexibility of the solid electrolyte tends to be improved. When the solid electrolyte has both toughness and flexibility, the ionic conductivity and cation transport number are less likely to fluctuate even when the solid electrolyte is bent, and good battery performance tends to be achieved. The number-average molecular weight of the reaction product is measured by the method described in the Examples below.

[0059] The amount of carbonate groups per molecule of the reaction product is preferably 3 to 70% by mass, more preferably 5 to 50% by mass, and even more preferably 5 to 30% by mass. When the amount of carbonate groups per molecule of the reaction product is equal to or greater than the lower limit, the toughness of the solid electrolyte tends to be improved, and when it is equal to or less than the upper limit, the flexibility of the solid electrolyte tends to be improved. When the solid electrolyte has both toughness and flexibility, the ionic conductivity and cation transport number are less likely to change even when the solid electrolyte is bent, and good battery performance tends to be achieved. When the amount of carbonate groups per molecule of the reaction product is １It is determined by calculating the ratio of peaks based on hydrogen bonded to the carbon adjacent to the carbonate group in H-NMR, specifically by the method described in the Examples below.

[0060] The proportion of the polyisocyanate-derived structural units in the reaction product is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, and even more preferably 18 to 30% by mass. When the proportion of the polyisocyanate-derived structural units in the reaction product is equal to or greater than the lower limit, the toughness of the solid electrolyte is likely to be improved, and when it is equal to or less than the upper limit, the flexibility, ionic conductivity, and cation transport number of the solid electrolyte are likely to be improved. When the solid electrolyte has both toughness and flexibility, the ionic conductivity and cation transport number are less likely to change even when the solid electrolyte is bent, and good battery performance is likely to be achieved.

[0061] The proportion of each constituent unit in the reaction product can be determined, for example, as follows. The reaction product is placed in a pressure-resistant container coated with polytetrafluoroethylene together with pyridine and distilled water, and heated at 130°C for 15 hours. Thereafter, the pyridine is distilled off, and a solution is obtained by dissolving the product in tetrahydrofuran. This solution is used as a measurement solution and measured by preparative GPC (for example, LC-Force, product name of YMC Co., Ltd.), and the measurement solution corresponding to each peak in the obtained chromatogram is separated. For each of the measurement solutions corresponding to the separated peaks, the tetrahydrofuran is removed by drying under reduced pressure at 80°C for 1 hour, and for each of the remaining liquids, １ The resulting mixture is analyzed by H-NMR, whereby it is possible to identify which of the peaks corresponds to a structural unit derived from the polyol, which corresponds to a structural unit derived from the polyisocyanate, and which corresponds to a structural unit derived from the chain extender, and the content of each component is determined based on the peaks in the chromatogram obtained by GPC.

[0062] The glass transition temperature Tg of the reaction product is not particularly limited, but is preferably −60 to 0° C., more preferably −55 to −10° C., and even more preferably −50 to −15° C. When the glass transition temperature Tg of the reaction product is within the above preferred range, the reaction product has better low-temperature properties. The glass transition temperature Tg of the reaction product is measured by the method described in the Examples below.

[0063] The breaking strength of the reaction product is not particularly limited, but is preferably 1.0 MPa or more, more preferably 1.5 MPa or more, and even more preferably 5.0 MPa or more. The breaking elongation of the reaction product is not particularly limited, but is preferably 1000% or more, more preferably 1100% or more, and even more preferably 1200% or more. The toughness of the reaction product is not particularly limited, but is preferably 40 MJ / m ３ More preferably, 45 MJ / m ３ More preferably, 50 MJ / m ３ The "breaking strength," "breaking elongation," and "toughness" herein are measured in the same manner as in the examples.

[0064] The content of the reaction product is preferably 10 to 95 mass %, more preferably 15 to 90 mass %, and even more preferably 20 to 85 mass %, based on the total amount of the solid electrolyte. When the content of the reaction product is equal to or greater than the lower limit, the ionic conductivity and cation transport number of the solid electrolyte tend to be better, while when the content is equal to or less than the upper limit, the toughness of the solid electrolyte tends to be better.

[0065] (Metal Salt) As the metal salt, various metal salts consisting of electrically positively charged compounds and electrically negatively charged compounds can be used. From the viewpoint of further improving ionic conductivity, the metal salt is preferably at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts, which have a high ionization tendency and are easily converted into cations, and more preferably an alkali metal salt. Examples of the alkali metal salt include lithium salt, sodium salt, and potassium salt. Specific examples of the metal salt include LiBF ４ , LiPF ６, LiAlCl ４ , LiSbF ６ , LiNbF ６ , LiAsF ６ , LiNH ２ , LiF, LiCl, LiSCN, LiCF ３ SO ３ , LiC ６ H ５ SO ３ , LiBr, LiI, LiCN, LiClO ４ , LiNO ３ , Li ＋ (CF ３ SO ２ ) ２ N － (lithium bis(trifluoromethanesulfonyl)imide: LiTFSI), C ６ H ５ COOLi, NaCl, NaBr, NaF, NaI, NaClO ４ , NaCN, NaPF ６ , Mg ２＋ [(CF ３ SO ２ ) ２ N － ] ２ (Magnesium bis(trifluoromethanesulfonyl)imide: MgTFSI), Mg(BH ４ ) ２ (magnesium borohydride), Mg[B(O ２ C ２ (CF ３ ) ４ ) ２ ] ２ (Mg(FPB) ２ ), PhMgCl, EtMgBr, Mg(HMDS) ２ , Mg[BBuPh ２ ] ２ Among these, LiTFSI and NaPF are preferred because they tend to have good ionic conductivity. ６ and MgTFSI, and LiTFSI, NaPF ６ , MgTFSI is more preferred.

[0066] The metal salt is preferably uniformly dispersed in the electrolyte containing the reaction product. As a method for dispersion, the metal salt may be directly mixed in the electrolyte in a solid state, or may be dispersed by a method such as dissolving it in a solvent and then mixed.

[0067] The content of the metal salt is preferably 0.01 to 50 mass %, more preferably 0.1 to 40 mass %, and even more preferably 0.5 to 30 mass %, based on the total amount of the solid electrolyte. When the content of the metal salt is equal to or greater than the lower limit, the ionic conductivity of the solid electrolyte tends to be improved, while when the content is equal to or less than the upper limit, the cation transference number of the solid electrolyte tends to be improved.

[0068] The solid electrolyte of the present invention may further contain a plasticizer from the viewpoint of improving toughness. The plasticizer is not particularly limited, and examples thereof include diethylene glycol dimethyl ether, di-2-ethylhexyl phthalate, dibutyl phthalate, dilauryl phthalate, dioctyl adipate, diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diisodecyl adipate, tributyl phosphate, trioctyl phosphate, propylene glycol polyester adipate, butylene glycol polyester adipate, epoxidized soybean oil, chlorinated paraffin, and liquid paraffin. These may be used alone or in combination of two or more.

[0069] When the solid electrolyte of the present invention contains a plasticizer, the content thereof is preferably 0.1 to 50 mass %, more preferably 0.5 to 45 mass %, and even more preferably 1 to 40 mass %, based on the total amount of the solid electrolyte.

[0070] The solid electrolyte of the present invention may further contain a filler from the viewpoint of improving the toughness of the solid electrolyte. The filler is not particularly limited, and examples thereof include carbon black, aluminum hydroxide, calcium carbonate, titanium oxide, aluminum oxide, silica, glass, bone powder, wood powder, fiber flakes, cellulose, and cellulose nanofibers. These may be used alone or in combination of two or more.

[0071] When the solid electrolyte of the present invention contains a filler, the content thereof is preferably 0.1 to 30 mass %, more preferably 0.2 to 25 mass %, and even more preferably 0.5 to 20 mass %, based on the total mass of the solid electrolyte. When the content of the filler is within the above range, the ionic conductivity can be further improved.

[0072] In addition to the above-described components, the solid electrolyte of the present invention may contain, as necessary, components that are generally blended in this type of material, within the range that does not impair the effects of the present invention. For example, the solid electrolyte may contain additives such as an antioxidant, a light stabilizer, a photosensitizer, and a flame retardant.

[0073] The content of the reaction product and metal salt contained in the solid electrolyte of the present invention is preferably 50% by mass or more, and more preferably 60% by mass or more.

[0074] The method for producing the solid electrolyte of the present invention is not particularly limited, and can be obtained, for example, by mixing the reaction product of the polyol and the polyisocyanate, the metal salt, and a plasticizer, a filler, and an additive that are optionally contained, and drying the mixture.

[0075] [Battery] The battery of the present invention includes the above-described solid electrolyte. Therefore, the battery has excellent toughness, ionic conductivity, and cation transport number, and can be used as a flexible battery. The battery of the present invention can be obtained by joining various known positive and negative electrode materials to the above-described solid electrolyte. The positive electrode material is LiMnO ２ , LiMn ２ O ４ , LiCoO ２ , Li ２ Cr ２ O ７ , LiNiO ２ , Li ２ CrO ４ Examples of the negative electrode material include hard carbon, soft carbon, lithium metal, etc. The hard carbon, soft carbon, and lithium metal used as the negative electrode material can be appropriately used in a microstructure such as laminated, spherical, fibrous, spiral, or fibril, and the shape of the negative electrode material can be flat, corrugated, rod, powder, or the like.

[0076] The exterior packaging material for packaging the battery can be aluminum foil, aluminum-deposited organic film, etc. Various known organic film materials can be used, and specific examples include polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, nylon, and polyethylene tetrafluorate.

[0077] Examples of articles equipped with the battery include flexible devices such as wearable devices, electrochromic displays, and implant devices.

[0078] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0079] <Evaluation Test> (Hydroxyl Value) The hydroxyl value of the polyol was calculated in accordance with JIS K 1557:2007 Method B using a phthalating reagent.

[0080] (Number Average Molecular Weight (Mn) and Molecular Weight Distribution (Mw / Mn)) The number average molecular weight (Mn) of the polyurethane resins obtained in Synthesis Examples 1 to 3, as well as the number average molecular weight (Mn) and weight average molecular weight (Mw) of the polyol were measured by gel permeation chromatography (GPC). The Mw / Mn of the polyol was calculated from the Mn and Mw. Tetrahydrofuran was used as the solvent. A calibration curve was prepared using polystyrene with a known molecular weight when measuring the polyurethane resins obtained in Synthesis Examples 1 to 3, and using polypropylene glycol with a known molecular weight converted into a hydroxyl value when measuring the polyol. That is, the number average molecular weight of the polyurethane resin was calculated as a molecular weight converted into polystyrene, and the number average molecular weight of the polyol was calculated as a molecular weight converted into polypropylene glycol.

[0081] (Glass Transition Temperature) The Tg of the polyurethane resins obtained in Synthesis Examples 1 to 3 was measured in accordance with JIS K7121:2012. Specifically, each polyurethane resin of Synthesis Examples 1 to 3 was laminated onto a silicone release-treated PET film, and heat-pressed at 150 to 180°C so that the thickness after pressing was 150 μm to obtain a test specimen. The glass transition temperature of the obtained test specimen was measured using a dynamic viscoelasticity measuring device (EXSTAR 6000 DMS6100, manufactured by Seiko Instruments Inc.). The measurement conditions were a temperature range of -100°C to +130°C, and a heating rate of 3°C / min.

[0082] (Oxyethylene Group Content (Ethylene Oxide Unit (EO Unit) Content) and Oxypropylene Group Content (Propylene Oxide Unit (PO Unit) Content)) The oxyethylene group content (ethylene oxide unit content) and the oxypropylene group content (propylene oxide unit content) relative to the total amount of oxyalkylene groups in a polyoxyalkylene polycarbonate diol are １ The monomer composition of the oxyalkylene chain was determined using H-NMR, and the ethylene oxide unit content and propylene oxide unit content were determined from the area ratio of the signal of the methyl group in the propylene oxide unit to the signals of the methylene groups in the propylene oxide unit and the ethylene oxide unit.

[0083] (Hard Segment Content) In each example, the hard segment content is a value (% by mass) calculated using the following formula (I): (mass of polyisocyanate + mass of chain extender) / (mass of polyisocyanate + mass of chain extender + Q) × 100 (I) where, in Synthesis Example 1, Q represents the mass of the polyoxyalkylene polycarbonate diol (PEPCD + PO + EO), and in Synthesis Examples 2 and 3, Q represents the mass of the polyether polycarbonate (PEPCD).

[0084] (NCO Unit Content) In each example, the urethane bond content is a value (% by mass) calculated using the following formula (II): (mass of polyisocyanate) / (mass of polyisocyanate+mass of chain extender+Q)×100 (II), where Q is the same as in formula (I).

[0085] (Carbonate Group Content) The number of repeating units of carbonate groups per molecule of polyol was measured by dissolving each polyol in deuterated chloroform to a concentration of 10% by mass and measuring the number of repeating units of carbonate groups per molecule with a resolution of 400 MHz (JNM-ECZ400SJNM, product name of JEOL Ltd.). １ H-NMR is measured and calculated from the peak based on the hydrogen atom bonded to the carbon adjacent to the carbonate group. The carbonate group content is the amount of carbonate groups per molecule of polyol, and is specifically calculated by the following formula (III): Carbonate group content (%) = (molecular weight of carbonate group) × (number of repeating units of carbonate group per molecule) / (number average molecular weight of polyol) × 100 (III) (Here, the molecular weight of the carbonate group (-O-C=O-O-) is 60.01.)

[0086] (Tensile Properties) The solid electrolyte was poured into a silicone mold so that the thickness after drying would be 0.1 μm, and dried at 80°C. Then, dumbbell-shaped specimens were punched out to obtain test specimens. The resulting test specimens were measured for breaking strength (unit: MPa) and breaking elongation (unit: %) in accordance with JIS K 7311 (1995) using a Tensilon (product name: RTG-1310, manufactured by A&D Co., Ltd.) at a tensile speed of 50 mm / min. The energy required for breaking (unit: MJ / m) was calculated from the area of ​​the obtained stress-strain curve. ３ ) was calculated. The energy required for breaking is an index of toughness, and the larger the value, the better the toughness of the solid electrolyte. If the breaking strength is in the range of 1.0 MPa or more, it can be said that the mechanical strength of the solid electrolyte is good. If the breaking elongation is in the range of 1000% or more, it can be said that the flexibility of the solid electrolyte is good. The energy required for breaking is 40 MJ / m ３ If the thickness falls within the above range, the toughness of the solid electrolyte can be said to be good.

[0087] (Ionic Conductivity) The solid electrolyte was poured into a silicone mold so that the thickness after drying was 2 mm and dried at 80°C. Next, a cylindrical specimen with a diameter of 5 mm was punched out to obtain a test specimen. The ionic conductivity (σ) of the obtained test specimen was evaluated by preparing a measurement cell in which the test specimen was sandwiched between a pair of electrodes (made of SUS: thickness 4 mm x diameter 20 mm), measuring the complex impedance using this, and calculating the logarithm of the ionic conductivity (log(σ)) based on the following formula (IV): log(σ) = log(d / (R x A)) (IV) (where R is the bulk resistance value, d is the thickness of the test specimen, and A is the area of ​​the electrode). When complex impedance is measured, the frequency dependence is observed due to the migration of ions along the potential gradient, as well as the charging and discharging of the electric double layer and electrode reactions. This frequency dependence was plotted on a plane with the real part on the horizontal axis and the imaginary part on the vertical axis (Cole-Cole plot), and the value of the equivalent circuit that explains the locus (resistance value, unit: S / cm) was determined. The measurement was carried out at temperatures of 15°C and 23°C.

[0088] (Cation transference number) The solid electrolytes of Examples 5 and 6 were poured into a silicone mold so that the thickness after drying would be 30 μm, and dried at 80° C. Then, they were punched out into a circle with a diameter of 10 mm to obtain a test specimen. The cation transference number (t ＋ ) was prepared by sandwiching the test specimen between a pair of electrodes (Li foil: diameter 4 mm) to prepare a measurement cell, and impedance measurement and chronoamperometry measurement were carried out using this. The obtained current values ​​in the initial state and steady state (I ０ , I Ｓ ) and interface resistance (R １ ０ , R １ Ｓ The cation transference number was calculated from the above data by the Bruce-Vincent-Evance method based on the following formula (V). Note that the larger the cation transference number, the better the result. ＋ =I Ｓ (ΔV-I ０ R １ ０ ) / I ０ (ΔV-I Ｓ R １ Ｓ ) (V)

[0089] <Synthesis of Polyurethane Resin> (Synthesis Example 1) Polyether polycarbonate diol (PEPCD) (product name: NT1002, manufactured by Mitsubishi Chemical Corporation, transparent viscous liquid, Mn: 1,000, glass transition temperature: −78° C.) (in general formula (2), R １ , R ２ , R ３ : n-butylene group, a: 3.2, n: 2.7, m: 3.2) was used as an initiator. Using 0.02 parts by mass of zinc hexacyanocobaltate complex (TBA-DMC catalyst) whose ligand is t-butyl alcohol as a ring-opening polymerization catalyst relative to 100 parts by mass of this initiator, 50 parts by mass of propylene oxide (PO) and 50 parts by mass of ethylene oxide (EO) as cyclic ethers were subjected to ring-opening addition polymerization at 130°C for 4 hours in a reaction vessel to obtain polyoxyalkylene polycarbonate diol (a1) (in general formula (2), R １ and R ３ : n-butylene group, R ２ 266 g of a polyoxyalkylene polycarbonate diol (a1) was obtained (a: n-butylene group, ethylene group, and isopropylene group, a: 3.2, n: 2.7, m: 19). The resulting polyoxyalkylene polycarbonate diol (a1) was a transparent liquid. The molecular weight calculated from the structure of the PO / EO moieties in the polyoxyalkylene polycarbonate diol (a1) calculated from the charged amount of PO (50 parts by mass) and the charged amount of EO (50 parts by mass) was 1,000. The resulting polyoxyalkylene polycarbonate diol (a1) had a hydroxyl value of 54.7 mg KOH / g, Mn of 2,200, and Mw / Mn of 1.13. The content of oxyethylene groups relative to the total amount of oxyalkylene groups in the polyoxyalkylene polycarbonate diol (a1) was 31 mass% and the content of oxypropylene groups was 23 mass%. Note that a, n, and m are theoretically calculated values.

[0090] 266 g of the resulting polyoxyalkylene polycarbonate diol (a1), 73.4 g of 4,4'-diphenylmethane diisocyanate (hereinafter sometimes referred to as "MDI"), and 3.5 g of antioxidant (Irganox 1010) were mixed, heated to 80°C, and reacted for 3 hours to obtain a polyurethane resin precursor (isocyanate group index: 226). Next, 15.3 g of 1,4-butanediol as a chain extender was added to the resulting polyurethane resin precursor, and the resulting mixture was transferred to a stainless steel pallet and reacted for an additional 4 hours at 130°C to obtain a polyurethane resin (A1) with a hard segment content of 25% by mass and an NCO unit content of 20.7% by mass. The resulting polyurethane resin (A1) had an Mn of 86,000 and a Tg of -42°C. The amount of carbonate groups per molecule of polyurethane resin (A1) was 5.5% by mass.

[0091] Synthesis Example 2 In a reaction vessel, PEPCD (product name: NT2002, manufactured by Mitsubishi Chemical Corporation, viscous liquid, Mn: 2,090, glass transition temperature: −71° C.) (in general formula (2), R １ , R ２ , R ３ 266 g of methyl 2,4-diol (a: n-butylene group, a: 3.2, n: 6.3, m: 3.2), 73.9 g of MDI, and 3.5 g of antioxidant (Irganox 1010) were mixed and heated to 80°C for 5 hours to produce a polyurethane resin precursor (isocyanate group index: 215). Next, 14.8 g of 1,4-butanediol as a chain extender was added to the resulting polyurethane resin precursor, and the resulting mixture was transferred to a stainless steel pallet and further reacted at 180°C for 3 hours to produce a polyurethane resin (A2) with a hard segment content of 25% by mass and an NCO unit content of 20.8% by mass. The resulting polyurethane resin (A2) had an Mn of 88,400 and a Tg of -42°C. The amount of carbonate groups per molecule of polyurethane resin (A2) was 13.6% by mass.

[0092] (Synthesis Example 3) In a reaction vessel, polycarbonate diol (PCD) (product name: T6002, manufactured by Asahi Kasei Corporation, solid, Mn: 2,100) (in general formula (2), R １ , R３ 266 g of methyl methyl ether (a:1, n:18, m:0), 73.7 g of MDI, and 3.5 g of antioxidant (Irganox 1010) were mixed and heated to 80°C for 3 hours to produce a polyurethane resin precursor (isocyanate group index: 226). Next, 12.4 g of 1,4-butanediol as a chain extender was added to the resulting polyurethane resin precursor, and the resulting mixture was transferred to a stainless steel pallet and further reacted at 130°C for 4 hours to produce polyurethane resin (A3) with a hard segment content of 25% by mass and an NCO unit content of 20.9% by mass. The resulting polyurethane resin (A3) had an Mn of 71,400 and a Tg of -18°C. The amount of carbonate groups per molecule of polyurethane resin (A3) was 38.9% by mass.

[0093] (Examples 1 to 7) The components were mixed in the composition ratios shown in Table 1 to obtain solid electrolytes of Examples 1 to 7. The obtained solid electrolytes were evaluated for tensile properties, ionic conductivity, and cation transport number by the methods described above. Examples 1 to 5 are working examples, and Examples 6 and 7 are comparative examples. The abbreviations in the table are as follows. [Polyurethane resin] A1: Polyurethane resin obtained in Synthesis Example 1 A2: Polyurethane resin obtained in Synthesis Example 2 A3: Polyurethane resin obtained in Synthesis Example 3

[0094] [Resins other than polyurethane resins (reaction products of polyols having the structure represented by general formula (1) and polyisocyanates)] PEG: polyethylene glycol, manufactured by Sigma-Aldrich (number average molecular weight 100,000, number of moles of carbonate groups in the polymer is 0, Tg is -55°C). QPAC: QPAC-25, polycarbonate, manufactured by EMPOWER MATERIALS (number average molecular weight 101,000, number of moles of carbonate groups in the polymer is 1, Tg is 10°C).

[0095] [Metal Salts] LiTFSI: lithium bis(trifluoromethanesulfonyl)imide, manufactured by Morita Chemical Industry Co., Ltd.

[0096] [Plasticizer] DEGDME: Diethylene glycol dimethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd.

[0097] [Filler] Silica: AGC Si-Tech Co., Ltd. NP-30

[0098]

[0099] It can be seen that the solid electrolytes of Examples 1 to 5 are excellent in toughness and ionic conductivity, and the solid electrolyte of Example 5 is excellent in cation transference number.

Claims

1. A solid electrolyte comprising a reaction product of a polyol having a structure represented by the following general formula (1) and a polyisocyanate, and a metal salt. 【Chemical 1】 (In the formula, A represents -(R １ O) ａ C(=O)O-, and B represents -R ２ O-. n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms. a is a number from 1 to 30.) When a is 2 or more, a plurality of (R １ O) may be the same or different. The plurality of (R １ O) may be bonded in a block form or in a random form. When there are a plurality of A's, the plurality of A's may be the same or different. When there are a plurality of B's, the plurality of B's may be the same or different. The bonding order of A, B and R ３ is not limited. The plurality of A's and the plurality of B's may be bonded in a block form or in a random form.)

2. The solid electrolyte according to Claim 1, wherein the ratio of A to the total of A and B in the general formula (1) is 3 to 100% by mass.

3. The solid electrolyte according to Claim 1, wherein B in the general formula (1) contains at least one selected from the group consisting of an oxyethylene group and an oxypropylene group.

4. The solid electrolyte according to Claim 3, wherein the ratio of the oxyethylene group contained in B in the general formula (1) is 25 to 100% by mass, and the ratio of the oxypropylene group is 0 to 75% by mass.

5. The solid electrolyte according to Claim 1, wherein the number average molecular weight of the polyol is 500 to 15,000.

6. The solid electrolyte according to Claim 1, wherein the polyol is a diol having a structure represented by the following general formula (2). 【Chemical 2】 (wherein n is a number from 1 to 170, and m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms. a is a number from 1 to 30.) When a is 2 or more, the plurality of (R １ O)'s may be the same or different. The plurality of (R １ O)'s may be bonded in a block form or randomly. When there are a plurality of structures represented by "-(R １ O) ａ C(=O)O-", the plurality of structures represented by "-(R １ O) ａ C(=O)O-" may be the same or different. When there are a plurality of structures represented by "-(R ２ O)-", the plurality of structures represented by "-(R ２ O)-" may be the same or different. The bonding order of the structure represented by "-(R １ O) ａ C(=O)O-", the structure represented by "-(R ２ O)-" and R ３ is not limited. The plurality of structures represented by "-(R １ O) ａ C(=O)O-" and the plurality of structures represented by "-(R ２ O)-" may be bonded in a block form or randomly. )

7. The solid electrolyte according to Claim 1, wherein the number average molecular weight of the reaction product is 20,000 to 150,000.

8. The solid electrolyte according to Claim 1, wherein the amount of carbonate groups per molecule of the reaction product is 3 to 70% by mass.

9. The solid electrolyte according to Claim 1, wherein the polyisocyanate is a diisocyanate.

10. The solid electrolyte according to Claim 1, wherein the metal salt is at least one selected from the group consisting of an alkali metal salt and an alkaline earth metal salt.

11. The solid electrolyte according to Claim 1, further comprising a plasticizer.

12. The solid electrolyte according to Claim 1, further comprising a filler.

13. A method for producing a solid electrolyte comprising a reaction product of a diol represented by the following general formula (2) and a polyisocyanate, and a metal salt. [Chemical Formula 3] (wherein, n is a number from 1 to 170, m is a number from 0 to 170. R １ , R ２ and R ３ each independently represents a divalent hydrocarbon group having 2 to 10 carbon atoms. a is a number from 1 to 30.) When a is 2 or more, a plurality of (R １ O) may be the same or different. The plurality of (R １ O) may be bonded in a block form or in a random form. When there are a plurality of structures represented by "-(R １ O) ａ C(=O)O-", the plurality of structures represented by "-(R １ O) ａ C(=O)O-" may be the same or different. When there are a plurality of structures represented by "-(R ２ O)-", the plurality of structures represented by "-(R ２ O)-" may be the same or different. The bonding order of the structure represented by "-(R １ O) ａ C(=O)O-", the structure represented by "-(R ２ O)-" and R ３ is not limited. The plurality of structures represented by "-(R １ O) ａ C(=O)O-" and the plurality of structures represented by "-(R ２ O)-" may be bonded in a block form or in a random form.)

14. The method for producing a solid electrolyte according to Claim 13, wherein the diol is a polyoxyalkylene polycarbonate diol obtained by ring-opening addition polymerization of a cyclic ether in the presence of a ring-opening polymerization catalyst using a polycarbonate diol or a polyether polycarbonate diol as an initiator.

15. The method for producing a solid electrolyte according to Claim 14, wherein the cyclic ether contains at least one selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide.

16. The cyclic ether includes ethylene oxide and propylene oxide, and the proportion of ethylene oxide in the total of ethylene oxide and propylene oxide in the polyoxyalkylene polycarbonate diol is 25 to 100% by mass. The method for producing a solid electrolyte according to claim 14 or 15.

17. A battery comprising the solid electrolyte according to any one of claims 1 to 12.

18. A flexible device comprising the battery according to claim 17.

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