Electrolyte for fluoride battery, polymer electrolyte, and fluoride battery

Abstract

To provide an electrolyte for a fluoride battery that is low in volatility and flame retardant, as well as a polymer electrolyte and a fluoride battery that use the electrolyte for a fluoride battery.SOLUTION: An electrolyte for a fluoride battery includes a fluoropolyether and a fluoride salt.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to an electrolyte for a fluoride battery, a polymer electrolyte, and a fluoride battery. [Background technology]

[0002] 2. Description of the Related Art With the trend toward lighter and smaller electrical appliances in recent years, electrochemical devices with high energy density have been developed.

[0003] Fluoride ion batteries, which are one type of electrochemical device, use fluoride ions (F - ) as a charge carrier and is characterized by its high voltage, and various studies are currently underway (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2014-501434 [Patent Document 2] Patent Publication No. 2022-128927 Summary of the Invention [Problem to be solved by the invention]

[0005] The electrolyte solutions described in Patent Documents 1 and 2 are highly volatile and highly flammable, and therefore there is room for improvement in terms of ease of handling in high-temperature environments.

[0006] An object of the present disclosure is to provide an electrolyte solution for a fluoride battery that is low in volatility and flame retardant, as well as a polymer electrolyte and a fluoride battery that use the electrolyte solution for a fluoride battery. [Means for solving the problem]

[0007] The present disclosure (1) is an electrolyte for a fluoride battery comprising a fluoropolyether and a fluoride salt.

[0008] The present disclosure (2) is the electrolyte solution for a fluoride battery according to the present disclosure (1), wherein the fluoropolyether is at least one of the following formulae (1) to (4): (1)R 1 -O-Ra 1 -Rb 1 -O-Ra 1 -R 1 (2)R 2 -Rb 2 -O-Ra 2 -Rb 2 -R 2 (3)R 3 -Rb 3 -O-Ra 3 -R 3 (4)R 4 -Rb 4 -R 4 (In the formula, Ra 1 ~Ra 3 each independently represents a group containing a fluorine-free alkylene unit and / or a fluorine-free oxyalkylene unit, Ra 1 ~Ra 3 each oxyalkylene unit is independently -CHCHO- or -CHCH(J)O-; Each J is independently an alkyl group or an aryl group; Rb 1 ~Rb 4 are each independently a fluoropolyether group represented by the following formula (5): R 1 ~R 3 each independently represents a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, or a fluoroalkyl group having 1 to 3 carbon atoms, R 4 are each independently a fluorine atom, a hydrogen atom, a hydroxyl group, an aldehyde group, a carboxylic acid group, an alkyl ester group having 1 to 10 carbon atoms, an amide group which may have a substituent, or an amino group which may have a substituent. (5)-Rf 1-Rf-O-Rf 2 - (In the formula, Rf 1 and Rf 2 each independently represents an alkylene group having 1 to 16 carbon atoms which may be substituted by a fluorine atom, Rf is a divalent fluoropolyether group.

[0009] This disclosure (3) relates to the Ra 1 ~Ra 3 are each independently a polyoxyalkylene group represented by the following formula (Ra-I): (Ra-I): -(CH2CH2O)r(CH2CH(CH3)O)s(CH2CH(CH2CH3)O)t(CH2CH(Ph)O)u- (In the formula, r, s, t, and u are each independently 0 or an integer of 1 or more, and r+s+t+u is 4 to 50.)

[0010] This disclosure (4) relates to the Ra 1 ~Ra 3 The electrolyte solution for a fluoride battery according to the present disclosure (2) or (3), wherein the number average molecular weight of the electrolyte is 40 to 4,000.

[0011] The present disclosure (5) is the electrolyte solution for a fluoride battery according to any one of the present disclosures (2) to (4), in which each Rf is independently a fluoropolyether group represented by the following formula (Rf-I): Formula (Rf-I): -(OC6F 12 )a-(OC5F 10 )b-(OC4F8)c-(OC3Rc6)d-(OC2F4)e-(OCF2)f- (In the formula, each Rc is independently a hydrogen atom, a fluorine atom, or a chlorine atom, a, b, c, d, e, and f each independently represent an integer of 0 to 200; the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of each repeat unit to which a, b, c, d, e, or f is assigned is arbitrary; When all Rc's are hydrogen atoms or chlorine atoms, at least one of a, b, c, e, and f is 1 or greater.

[0012] The present disclosure (6) is the electrolyte solution for a fluoride battery according to any one of the present disclosures (2) to (5), in which the Rfs are each independently a group represented by the following formula (Rf-II) or the following formula (Rf-I-II): Formula (Rf-II): -(OC3F6)d-(OC2F4)e- (In the formula, d is an integer of 1 to 200, and e is 0 or 1.) Formula (Rf-I-II): -(OC4F8)c-(OC3F6)d-(OC2F4)e-(OCF2)f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200; The sum of c, d, e, and f is 2 or more, The order of the repeating units marked with c, d, e, or f is arbitrary.

[0013] This disclosure (7) relates to the R 1 ~R 3 are each independently a methyl group, an ethyl group, a trifluoromethyl group, or a pentafluoroethyl group.

[0014] The present disclosure (8) is the electrolyte solution for a fluoride battery according to any one of the present disclosures (1) to (7), in which the fluoride salt is ammonium fluoride or a metal fluoride.

[0015] The present disclosure (9) is the electrolyte for a fluoride battery according to the present disclosure (8), wherein the ammonium fluoride is an alkylammonium fluoride having a neopentyl group.

[0016] The present disclosure (10) is the electrolyte solution for a fluoride battery according to any one of the present disclosures (1) to (9), in which the content of the fluoride salt is 0.1 to 10 mass %.

[0017] The present disclosure (11) is an electrolyte solution for a fluoride battery according to any one of the present disclosures (1) to (10), which is liquid at 25°C.

[0018] The present disclosure (12) is a method for producing a ferroelectric liquid having an ionic conductivity of 1.0×10 -9 ~1.0×10 -4 The electrolyte solution for a fluoride battery according to any one of the present disclosures (1) to (11) has a conductivity of 1.0 S / cm.

[0019] The present disclosure (13) is a polymer electrolyte containing the electrolyte solution for a fluoride battery according to any one of the present disclosures (1) to (12).

[0020] The present disclosure (14) is a fluoride battery including the electrolyte for a fluoride battery according to any one of the present disclosures (1) to (12).

[0021] The present disclosure (15) is a fluoride battery comprising the polymer electrolyte according to the present disclosure (13). Effect of the Invention

[0022] According to the present disclosure, it is possible to provide a low-volatility and flame-retardant electrolyte solution for a fluoride battery, as well as a polymer electrolyte and a fluoride battery using the electrolyte solution for a fluoride battery. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present disclosure will now be described in detail.

[0024] <Composition> The present disclosure relates to a fluoride battery electrolyte comprising a fluoropolyether and a fluoride salt.

[0025] Since the electrolyte solution of the present disclosure has the above-mentioned composition, it can achieve low volatility and flame retardancy.

[0026] As the fluoropolyether, at least one of the following formulae (1) to (4) can be suitably used. These compounds include Rb 1 ~Rb 4 The compound represented by the following formulae (1) to (3) can realize low volatility and flame retardancy by the moiety. 1 ~Ra 3 This portion improves the solubility of the fluoride salt. (1)R 1 -O-Ra 1 -Rb 1 -O-Ra 1 -R 1 (2)R 2 -Rb 2 -O-Ra 2 -Rb 2 -R 2 (3)R 3 -Rb 3 -O-Ra 3 -R 3 (4)R 4 -Rb 4 -R 4 (In the formula, Ra 1 ~Ra 3 each independently represents a group containing a fluorine-free alkylene unit and / or a fluorine-free oxyalkylene unit, Ra 1 ~Ra 3 each oxyalkylene unit is independently -CHCHO- or -CHCH(J)O-; Each J is independently an alkyl group or an aryl group; Rb 1 ~Rb 4 are each independently a fluoropolyether group represented by the following formula (5): R 1 ~R 3 each independently represents a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, or a fluoroalkyl group having 1 to 3 carbon atoms, R 4are each independently a fluorine atom, a hydrogen atom, a hydroxyl group, an aldehyde group, a carboxylic acid group, an alkyl ester group having 1 to 10 carbon atoms, an amide group which may have a substituent, or an amino group which may have a substituent. (5)-Rf 1 -Rf-O-Rf 2 - (In the formula, Rf 1 and Rf 2 each independently represents an alkylene group having 1 to 16 carbon atoms which may be substituted by a fluorine atom, Rf is a divalent fluoropolyether group.

[0027] Ra 1 ~Ra 3 The alkylene unit may be linear or branched, but is preferably linear, and preferably has 1 to 3 carbon atoms.

[0028] Ra 1 ~Ra 3 When the oxyalkylene unit is -CHCH(J)O-, the alkyl group of J may be linear or branched, but is preferably linear. The number of carbon atoms in the alkyl group of J is preferably 1 to 3. Examples of the aryl group represented by J include a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0029] Ra 1 ~Ra 3 In the formula (I), the number of fluorine-free alkylene units and fluorine-free oxyalkylene units is preferably 4 to 50 in total.

[0030] Ra 1 ~Ra 3 Each of the groups preferably independently contains at least an oxyalkylene unit, and is more preferably a polyoxyalkylene group represented by the following formula (Ra-I). (Ra-I): -(CH2CH2O)r-(CH2CH(CH3)O)s-(CH2CH(CH2CH3)O)t-(CH2CH(Ph)O)u- (In the formula, r, s, t, and u are each independently 0 or an integer of 1 or more, and r+s+t+u is 4 to 50.)

[0031] In the above formula (Ra-I), r is preferably 1 or more, more preferably 2 or more, and is preferably 30 or less, more preferably 20 or less. s, t and u are preferably 10 or less, more preferably 5 or less, and further preferably 0. r+s+t+u is preferably 1 or more, more preferably 2 or more, and is preferably 20 or less, more preferably 10 or less.

[0032] Ra 1 ~Ra 3 The number average molecular weight of is preferably 40 or more, more preferably 100 or more, and is preferably 4000 or less, more preferably 1000 or less. In the present specification, Ra 1 ~Ra 3 The number average molecular weight of 1 This is a value measured by H-NMR.

[0033] Rb 1 ~Rb 4 In the above formula (5), Rf 1 and Rf 2 The alkylene group may be linear or branched, but is preferably linear. Rf 1 and Rf 2 The alkylene group is preferably a fluorine-substituted alkylene group substituted with a fluorine atom. Rf 1 and Rf 2 The alkylene group preferably has 1 to 3 carbon atoms.

[0034] Rb 1 ~Rb 4In the above formula (5), Rf may have a ring structure.

[0035] Rb 1 ~Rb 4 In the above formula (5), Rf is preferably a fluoropolyether group represented by the following formula (Rf-I). Formula (Rf-I): -(OC6F 12 )a-(OC5F 10 )b-(OC4F8)c-(OC3Rc6)d-(OC2F4)e-(OCF2)f- (In the formula, each Rc is independently a hydrogen atom, a fluorine atom, or a chlorine atom, a, b, c, d, e, and f each independently represent an integer of 0 to 200; the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of each repeat unit to which a, b, c, d, e, or f is assigned is arbitrary; When all Rc's are hydrogen atoms or chlorine atoms, at least one of a, b, c, e, and f is 1 or greater.

[0036] Rc is preferably a hydrogen atom or a fluorine atom, and more preferably a fluorine atom, That is, Rf in the formula (5) is preferably a perfluoropolyether group.

[0037] It is preferable that a, b, c, d, e and f each independently represent an integer of 0 to 100.

[0038] The sum of a, b, c, d, e and f is preferably 5 or more, more preferably 10 or more, and may be 15 or more or 20 or more. The sum of a, b, c, d, e and f is preferably 100 or less, more preferably 60 or less, and may be 50 or less or 30 or less.

[0039] Each repeat unit denoted by a, b, c, d, e, or f may be linear or branched. -(OC6F 12)- may be, for example, any of -(OCF2CF2CF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2CF2CF2)-, -(OCF2CF(CF3)CF2CF2CF2)-, -(OCF2CF2CF(CF3)CF2CF2)-, -(OCF2CF2CF2CF(CF3)CF2)-, or -(OCF2CF2CF2CF2CF(CF3))-. -(OC5F 10 )- may be, for example, any of -(OCF2CF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2CF2)-, -(OCF2CF(CF3)CF2CF2)-, -(OCF2CF2CF(CF3)CF2)-, or -(OCF2CF2CF2CF(CF3))-. -(OC4F8)- may be, for example, any of -(OCF2CF2CF2CF2)-, -(OCF(CF3)CF2CF2)-, -(OCF2CF(CF3)CF2)-, -(OCF2CF2CF(CF3))-, -(OC(CF3)2CF2)-, -(OCF2C(CF3)2)-, -(OCF(CF3)CF(CF3))-, -(OCF(C2F5)CF2)-, or -(OCF2CF(C2F5))-. -(OC3F6)- (that is, in the above formula (Rf-I) where all Rc are fluorine atoms) may be, for example, any of -(OCF2CF2CF2)-, -(OCF(CF3)CF2)-, and -(OCF2CF(CF3))-. -(OC2F4)- may be, for example, -(OCF2CF2)- or -(OCF(CF3))-.

[0040] Rf may be a group represented by any one of the following formulas (Rf-II) to (Rf-IV). Formula (Rf-II): -(OC3F6)d-(OC2F4)e- (In the formula, d is an integer of 1 to 200, and e is 0 or 1.) Formula (Rf-I-II): -(OC4F8)c-(OC3F6)d-(OC2F4)e-(OCF2)f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer of 1 to 200; The sum of c, d, e, and f is 2 or more, The order of the repeating units marked with c, d, e, or f is arbitrary. Formula (Rf-I-III): -(R 20 -R 21 )g- (In the formula, R 20 is OCF2 or OC2F4, R 21 are OC2F4, OC3F6, OC4F8, OC5F 10 and OC6F 12 or a combination of two or three groups selected from these groups, g is an integer from 2 to 100. Formula (Rf-I-IV): -(OC6F 12 )a-(OC5F 10 )b-(OC4F8)c-(OC3F6)d-(OC2F4)e-(OCF2)f- (In the formula, e is an integer of 1 to 200, a, b, c, d, and f each independently represent an integer of 0 to 200; The order of each repeating unit with a, b, c, d, e, or f is arbitrary. Formula (Rf-IV): -(OC6F 12 )a-(OC5F 10 )b-(OC4F8)c-(OC3F6)d-(OC2F4)e-(OCF2)f- (In the formula, f is an integer of 1 to 200, a, b, c, d, and e each independently represent an integer of 0 to 200; The order of each repeating unit with a, b, c, d, e, or f is arbitrary.

[0041] In the above formula (Rf-II), d may be preferably 5-200, more preferably 10-100, and further preferably 10-30. The above formula (Rf-II) is preferably a group represented by -(OCF2CF2CF2)d- or -(OCF(CF3)CF2)d-.

[0042] In the above formula (Rf-I-II), e and f are each independently an integer of preferably 5 to 200, more preferably 10 to 200. The sum of c, d, e and f is preferably 5 or more, more preferably 10 or more, and may be 15 or more, or 20 or more. The above formula (Rf-I-II) is preferably a group represented by -(OCF2CF2CF2CF2)c-(OCF2CF2CF2)d-(OCF2CF2)e-(OCF2)f- or a group represented by -(OC2F4)e-(OCF2)f-, and more preferably a group represented by -(OC2F4)e-(OCF2)f-.

[0043] In the above formula (Rf-I-III), R 20 is preferably OC2F4, and R 21is preferably a group selected from OC2F4, OC3F6 and OC4F8, or a combination of two or three groups independently selected from these groups, and more preferably a group selected from OC3F6 and OC4F8. The combination of two or three groups independently selected from OC2F4, OC3F6 and OC4F8 is not particularly limited, and examples thereof include -OC2F4OC3F6-, -OC2F4OC4F8-, -OC3F6OC2F4-, -OC3F6OC3F6-, -OC3F6OC4F8-, -OC4F8OC4F8-, -OC4F8OC3F6-, -OC4F8OC2F4-, -OC Examples include 2F4OC2F4OC3F6-, -OC2F4OC2F4OC4F8-, -OC2F4OC3F6OC2F4-, -OC2F4OC3F6OC3F6-, -OC2F4OC4F8OC2F4-, -OC3F6OC2F4OC2F4-, -OC3F6OC2F4OC3F6-, -OC3F6OC3F6OC2F4-, and -OC4F8OC2F4OC2F4-. In the above formula (Rf-I-III), g is preferably an integer of 3 or more, more preferably an integer of 5 or more. The above g is preferably an integer of 50 or less. In the above formula (Rf-I-III), OC2F4, OC3F6, OC4F8, OC5F 10 , and OC6F 12 may be either linear or branched, and is preferably linear. In this embodiment, the above formula (Rf-I-III) is preferably -(OC2F4-OC3F6)g- or -(OC2F4-OC4F8)g-.

[0044] In the above formula (Rf-I-IV), e is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. The sum of a, b, c, d, e and f is preferably 5 or more, more preferably 10 or more, for example, 10 to 100.

[0045] In the above formula (Rf-IV), f is preferably an integer of 1 to 100, more preferably an integer of 5 to 100. The sum of a, b, c, d, e and f is preferably 5 or more, more preferably 10 or more, for example, 10 to 100.

[0046] In Rf, the ratio of e to f (hereinafter referred to as "e / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By making the e / f ratio 4 or less, the lubricity and chemical stability are further improved. The smaller the e / f ratio, the more the lubricity is improved. On the other hand, by making the e / f ratio 0.5 or more, the stability of the compound can be further improved. The larger the e / f ratio, the more the stability of the fluoropolyether structure is improved. In this case, the value of the e / f ratio is preferably 0.8 or more.

[0047] Rf is represented by the following formula (Rf-I-VI): -(OCF2CF2CF2)a-(OCF(CF3)CF2)b-(OCF2CF(CF3))c-(OCF2CF2)d-(OCF(CF3))e-(OCF2)f- (In the formula, a, b, c, d, e, and f each independently represent an integer of 0 to 200, the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of each repeating unit with a, b, c, d, e, or f is arbitrary. The group may be represented by the following formula:

[0048] Rf is represented by the following formula (Rf-I-VII): -(OCF2CF2)d-(OCF(CF3))e-(OCF2)f- (In the formula, d, e, and f each independently represent an integer of 0 to 200, the sum of d, e, and f is 1 or more, The order of the repeating units marked with d, e, or f is arbitrary. When Rf is this group, it is considered that the solubility of the salt is improved since the number of ether bonds increases and the cations of the salt are more easily coordinated.

[0049] In Rf, the ratio of d to f (hereinafter referred to as "d / f ratio") may be 0.5 to 4, preferably 0.6 to 3, more preferably 0.7 to 2, and even more preferably 0.8 to 1.4. By making the d / f ratio 4 or less, the lubricity and chemical stability are further improved. The smaller the d / f ratio, the more the lubricity is improved. On the other hand, by making the d / f ratio 0.5 or more, the stability of the compound can be further improved. The larger the d / f ratio, the more the stability of the fluoropolyether structure is improved. In this case, the value of the d / f ratio is preferably 0.8 or more.

[0050] Each Rf is preferably independently a group represented by the above formula (Rf-II) or (Rf-I-II), and more preferably a group represented by the above formula (Rf-I-II).

[0051] The number average molecular weight of Rf is not particularly limited, but is, for example, 500 to 30,000, preferably 1,500 to 30,000, and more preferably 2,000 to 10,000. In this specification, the number average molecular weight of Rf is 19 This is a value measured by F-NMR.

[0052] R 1 ~R 3 The alkyl group and the fluoroalkyl group may be linear or branched, but are preferably linear. R 1 ~R 3 Examples of the aryl group include a phenyl group, a 4-nitrophenyl group, a 4-acetylaminophenyl group, and a 4-methanesulfonylphenyl group.

[0053] R 1 ~R 3are each independently preferably an alkyl group having 1 to 3 carbon atoms or a fluoroalkyl group having 1 to 3 carbon atoms, more preferably a methyl group, an ethyl group, a trifluoromethyl group or a pentafluoroethyl group, and further preferably a methyl group, a trifluoromethyl group or a pentafluoroethyl group.

[0054] R 4 The alkyl ester group may be linear or branched.

[0055] R 4 Examples of the substituent that the amido group or amino group may have include an alkyl group, an alkoxy group, and a hydroxy group.

[0056] R 4 are each preferably independently a fluorine atom, a hydrogen atom, a hydroxyl group, an aldehyde group, a carboxylic acid group, an alkyl ester group having 1 to 10 carbon atoms, an amide group which may have a substituent, or an amino group which may have a substituent, and more preferably a fluorine atom. R 4 is a fluorine atom, R 4 -Rb 4 and Rb 4 -R 4 , i.e., R 4 -Rf 1 and Rf 2 -R 4 may each independently be a group selected from the group consisting of -CF3, -CF2CF3, and -CF2CF2CF3.

[0057] The fluoropolyether is particularly preferably the fluoropolyether represented by the above formula (1) because of its excellent ionic conductivity.

[0058] The above fluoropolyether is preferably liquid at any temperature between 25°C and 80°C because it has good ionic conductivity and the like. Examples of a form that is "liquid at any temperature between 25°C and 80°C" include a form that is solid at 25°C and liquid at 50°C, and a form that is solid at 50°C and liquid at 80°C. A form that is liquid at low temperatures and solid at high temperatures does not usually exist, and therefore is not included in the form that is "liquid at any temperature between 25°C and 80°C".

[0059] In the electrolyte for fluoride ion batteries of the present disclosure, the content of the fluoropolyether is preferably 60% by mass or more, more preferably 70% by mass or more, and furthermore 80% by mass or more. The upper limit is not particularly limited, but is usually 99% by mass or less, preferably 98% by mass or less.

[0060] The above-mentioned fluoride salt is not particularly limited as long as it generates fluoride ions, and may be an organic fluoride salt or an inorganic fluoride salt. The fluoride salt may be an ionic liquid. More specifically, ammonium fluoride, metal fluoride, etc. may be used. These may be used alone or in combination of two or more. Ammonium fluoride is preferred because of its good solubility.

[0061] Specific examples of the metal fluorides include alkali or alkaline earth fluorides (e.g., LiF, NaF, KF, CsF, MgF2, BaF2), transition metal fluorides (e.g., VF4, FeF3, MoF6, PdF2, AgF), main group metal fluorides (e.g., AlF3, PbF4, BiF3), and lanthanide or actinide fluorides (e.g., LaF3, YbF3, UF5). The metal fluorides are preferably LiF, NaF, KF, or CsF.

[0062] Examples of the ammonium fluoride include ammonium hydrogen fluoride, alkyl ammonium fluoride, etc. From the viewpoint of good solubility, alkyl ammonium fluoride is preferred.

[0063] The above alkyl ammonium fluorides are +It is preferable that the cation represented by -Rx4 is included. Each Rx is independently an alkyl group or a fluoroalkyl group, and an alkyl group is preferable. The carbon number of Rx is, for example, 1 to 10, and may be 5 or less, or 3 or less. The alkyl ammonium fluoride is preferably tetramethylammonium fluoride or tetrabutylammonium fluoride.

[0064] The alkyl group and fluoroalkyl group in the alkyl ammonium fluoride may be straight-chain or branched-chain, but it is preferable that at least one of them is branched-chain, and it is more preferable that they contain both branched-chain and straight-chain. The alkyl group and the fluoroalkyl group preferably have 1 or more carbon atoms, and preferably 10 or less, more preferably 8 or less, and further preferably 6 or less. The linear alkyl group and linear fluoroalkyl group each preferably have 1 or more carbon atoms, and preferably 10 or less, more preferably 5 or less, and further preferably 3 or less. The branched alkyl group and branched fluoroalkyl group each preferably have 1 or more, more preferably 3 or more, and even more preferably 4 or more carbon atoms, and preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less.

[0065] The alkylammonium fluoride is preferably an alkylammonium fluoride having a branched alkyl group having 5 carbon atoms, more preferably an alkylammonium fluoride having a neopentyl group, further preferably trimethylneopentylammonium fluoride or dimethyldineopentylammonium fluoride, and particularly preferably trimethylneopentylammonium fluoride.

[0066] In the electrolyte for a fluoride battery of the present disclosure, the content of the fluoride salt is preferably 0.1 mass % or more, more preferably 1 mass % or more, and preferably 10 mass % or less, more preferably 5 mass % or less.

[0067] In the fluoride battery electrolyte of the present disclosure, the fluoropolyether is generally used as a solvent. The content of the fluoropolyether is preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more, relative to the solvent. There is no particular upper limit, and it may be 100% by mass.

[0068] In the electrolyte for fluoride batteries of the present disclosure, a solvent other than the fluoropolyether may be used. Examples of the solvent other than the fluoropolyether include those conventionally known as non-aqueous solvents for fluoride ion batteries, such as carbonate-based solvents, ester-based solvents, ether-based solvents, and fluorobenzene-based solvents. Examples of the carbonate-based solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Examples of the ester-based solvents include cyclic esters such as γ-butyrolactone and γ-valerolactone, and chain esters such as methyl acetate and ethyl acetate. Examples of the ether-based solvents include cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, and chain ethers such as dimethoxyethane and glyme-based compounds. Examples of glyme-based compounds include diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. Examples of fluorobenzene-based solvents include 1,3-difluorobenzene, 1,2,4-trifluorobenzene, and 1,2,3,4-tetrafluorobenzene. These may be used alone or in combination of two or more. In the present disclosure, ether-based solvents are preferred, chain ethers are more preferred, and glyme-based compounds are even more preferred.

[0069] The fluoride battery electrolyte of the present disclosure may include at least one anion acceptor selected from the group consisting of tris(hexafluoroisopropyl)borate, tris(pentafluorophenyl)borane, difluorophenylboroxine, trifluorophenylboroxine, bis(trifluoromethyl)phenylboroxine, trifluoromethylphenylboroxine, triphenylboroxine, trimethoxyboroxine, fluorobis(2,4,6-trimethylphenyl)borane, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine, N,N-diethyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline, and fluoro(trifluoromethyl)phenylboroxine. These anion acceptors are believed to reversibly bind to fluoride ions in solution, increasing the amount of fluoride salt dissolved in the solution. In addition, it is believed that the reversible formation of complexes between these anion acceptors and fluoride ions reduces the amount of free fluoride ions in the solution, improving the stability of the cycle characteristics.

[0070] In the electrolyte for a fluoride battery of the present disclosure, the content of the anion acceptor is preferably 0.001 to 20 mass %, more preferably 0.01 to 15 mass %, further preferably 0.1 to 10 mass %, and particularly preferably 0.1 to 7 mass %, relative to the electrolyte.

[0071] The electrolyte solution may further contain polyethylene oxide having a weight average molecular weight of 2000 to 4000 and having -OH, -OCOOH, or -COOH at its terminal. By containing such a compound, the stability of the electrode interface is improved, and the characteristics of the fluoride battery can be improved. Examples of the polyethylene oxide include polyethylene oxide monool, polyethylene oxide carboxylic acid, polyethylene oxide diol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, etc. These may be used alone or in combination of two or more kinds. Among these, a mixture of polyethylene oxide monool and polyethylene oxide diol, and a mixture of polyethylene carboxylic acid and polyethylene dicarboxylic acid are preferred in terms of improving the characteristics of the fluoride battery.

[0072] If the weight-average molecular weight of the polyethylene oxide is too small, it may be easily decomposed by oxidation. The weight average molecular weight can be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0073] The content of the polyethylene oxide in the electrolyte is 1×10 -6 ~1×10 -2 If the content of the polyethylene oxide is too high, the characteristics of the fluoride battery may be impaired. The content of the polyethylene oxide is 5×10 -6 It is more preferable that it is mol / kg or more.

[0074] The electrolyte for a fluoride battery of the present disclosure is preferably liquid at 25°C.

[0075] The ionic conductivity of the electrolyte for a fluoride battery of the present disclosure is preferably 1.0×10 -9 S / cm or more, preferably 1.0×10 -8 S / cm or more, more preferably 1.0×10 -7 The upper limit is not particularly limited, but is preferably 1.0×10 -4 S / cm or less. The ionic conductivity can be measured at 25° C. using a SevenCompact S230 manufactured by Mettler Toledo.

[0076] The F ion transport number of the electrolyte for a fluoride battery of the present disclosure is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. The upper limit is not particularly limited, but is preferably 0.8 or less. The F ion transport number is determined by pulsed magnetic field gradient NMR measurements using F ions as the target nuclide (Science 362, 1144-1148 (2018)).

[0077] <Polymer electrolyte> The present disclosure also relates to a polymer electrolyte comprising the fluoride battery electrolyte of the present disclosure.

[0078] The polymer electrolyte of the present disclosure includes, for example, a gel electrolyte in which a polymer material is plasticized with the electrolyte for a fluoride battery of the present disclosure.

[0079] Examples of the polymer material include conventionally known polyethylene oxide, polypropylene oxide, and modified products thereof (JP Patent Publication Nos. 8-222270 and 2002-100405); polyacrylate polymers, polyacrylonitrile, fluororesins such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers (JP Patent Publication Nos. 4-506726, 8-507407, and 10-294131); and complexes of such fluororesins and hydrocarbon resins (JP Patent Publication Nos. 11-35765 and 11-86630). In particular, polyvinylidene fluoride is preferred.

[0080] <Fluoride battery> The present disclosure also relates to a fluoride battery comprising the fluoride battery electrolyte of the present disclosure or the polymer electrolyte of the present disclosure.

[0081] The fluoride battery of the present disclosure is preferably one that includes a positive electrode, a negative electrode, etc., and is particularly preferably a fluoride ion secondary battery that includes these.

[0082] As the positive electrode active material used in the positive electrode, for example, a metal that forms a metal fluoride can be used, and specific examples include Au, Pt, S, Ag, Fe, Co, Ni, Cu, Cr, Mo, W, V, Sb, Bi, Sn, In, Ce, Pb, etc. These may be used alone or in combination of two or more. In addition, it may be an alloy of two or more metals, or a fluoride of these metals. The positive electrode active material may be, for example, a foil, a compact, or one formed by a vapor deposition method.

[0083] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the electrode mixture, more preferably 80 to 99% by mass, in terms of high battery capacity. The content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0084] The negative electrode active material used in the negative electrode may be, for example, a material that absorbs and releases carrier ions, and may be a material that absorbs and releases carrier ions like a capacitor, or a material that inserts and releases carrier ions like an ion secondary battery. Specific examples include precious metals such as Pt, Au, and Ag; lithium metal; carbonaceous materials such as artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon alloys; and Li4Ti5O 12 ;etc.

[0085] In order to increase the capacity of the resulting electrode mixture, the content of the negative electrode active material is preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more in the electrode mixture, and the upper limit is preferably 99% by mass or less, more preferably 98% by mass or less.

[0086] The positive electrode current collector is not particularly limited as long as it is a conductor and has a redox potential nobler than the positive electrode active material, and examples of the positive electrode current collector include C, Au, Pt, Ag, Co, Mo, Cu, W, V, Sb, Bi, Sn, Ni, Pb, Fe, Cr, Zn, In, Ti, Ga, Mn, Al, and Zr. The negative electrode current collector can be the same as the positive electrode current collector.

[0087] The electrode mixture constituting the positive electrode or the negative electrode may contain a conductive assistant. The conductive assistant is not particularly limited, and examples thereof include carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and carbon materials such as amorphous carbon such as fullerene and VGCF, etc. These may be used alone or in any combination and ratio of two or more kinds.

[0088] The conductive assistant is used in an amount of usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, in the electrode mixture, and usually 50% by mass or less, preferably 30% by mass or less, more preferably 15% by mass or less.

[0089] The electrode mixture may contain a binder. The binder is not particularly limited, but examples thereof include polymer compositions such as SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), EPDM (ethylene-propylene-diene terpolymer), polyvinylidene fluoride, and tetrafluoroethylene.

[0090] The binder is used in an amount of usually 1.0% by mass or more, preferably 1.3% by mass or more, more preferably 1.6% by mass or more, and usually 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, based on the electrode active material.

[0091] The positive and negative electrodes may be produced by a conventional method, for example, a method of preparing a slurry containing an electrode composition, applying it to a current collector, and drying it.

[0092] The thicknesses of the positive electrode and the negative electrode are not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the mixture layer minus the thickness of the metal foil of the current collector is, as a lower limit, preferably 10 μm or more, more preferably 20 μm or more, and also preferably 500 μm or less, more preferably 450 μm or less on one side of the current collector.

[0093] The secondary battery containing the electrolyte for fluoride batteries of the present disclosure preferably further comprises a separator. The material and shape of the separator are not particularly limited as long as they are stable to the electrolyte and have excellent liquid retention, and any known separator can be used. Among them, it is preferable to use a material formed of a material stable to the electrolyte, such as a resin, glass fiber, or inorganic material, and to use a porous sheet or nonwoven fabric having excellent liquid retention.

[0094] Materials for the resin and glass fiber separator include, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. These materials may be used alone or in any combination and ratio of two or more. Among them, the separator is preferably a porous sheet or nonwoven fabric made of polyolefins such as polyethylene and polypropylene, because of its excellent electrolyte permeability and shutdown effect.

[0095] The material of the exterior case is not particularly limited as long as it is a material that is stable against the electrolyte used. Specifically, metals such as nickel-plated steel sheet, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminate film of resin and aluminum foil (laminate film) are used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloy, and laminate films are preferably used.

[0096] The shape of the secondary battery using the above-mentioned electrolyte solution is arbitrary, and examples of the shape include a cylindrical shape, a square shape, a laminated shape, a coin shape, a large shape, etc. The shapes and configurations of the positive electrode, the negative electrode, and the separator can be changed according to the shape of each battery.

[0097] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0098] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0099] The following compounds were used: Compounds 1-1 to 1-4 were liquids at 25°C. <Compound 1-1> CH3O(CH2CH2O) x1 CH2CF2(OCF2CF2) y (OCF2) z OCF2CH2O(CH2CH2O) x2 CH3 (x1:4, y: average 12.3, z: average 10.2, x2:4, (CH2CH2O) x1 Number average molecular weight: 176, (CH2CH2O) x2 Number average molecular weight: 176) <Compound 1-2> Compound with the same structure as compound 1-1 (x1: average 8.4, y: average 12.3, z: average 10.2, x2: average 8.4, (CH2CH2O) x1Number average molecular weight: 400, (CH2CH2O) x2 Number average molecular weight: 400) <Compound 1-3> CF2(CF3)CF2(OCF(CF3)CF2) x OCF(CF3)CH2O(CH2CH2O) y CH2C(CF3)F(OCF2C(CF3)F) z OCF2C(CF3)F2 (x: average 7, y: average 4.1, z: average 7, (CH2CH2O) y Number average molecular weight: 200) <Compound 1-4> CF2(CF3)CF2(OCF(CF3)CF2) x OCF(CF3)CH2O(CH2CH2O) y CH3 (x: average 7, y: 4, (CH2CH2O) y Number average molecular weight: 176)

[0100] <Compound 2-1> Ethyl methyl carbonate (EMC, Kishida Chemical Co., Ltd., boiling point 108°C, flash point 22°C) <Compound 2-2> Tetrafluoroethyl trifluoroethyl ether (Tokyo Chemical Industry Co., Ltd., boiling point 56°C, no flash point) <Compound 2-3> Triethylene glycol dimethyl ether (Tokyo Chemical Industry Co., Ltd., boiling point 216°C, flash point 108°C)

[0101] <lif> Lithium fluoride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) <naf> Sodium fluoride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) <kf> Potassium fluoride (Tokyo Chemical Industry Co., Ltd.) <csf> Cesium fluoride (Tokyo Chemical Industry Co., Ltd.) <tmaf> Tetramethylammonium fluoride (Sigma-Aldrich) <tbaf> Tetrabutylammonium fluoride (Sigma-Aldrich) <npaf> Trimethylneopentylammonium fluoride (Synthesis Example 6 below)

[0102] (Synthesis Example 1) Synthesis of Compound 1-1 In a nitrogen-substituted reaction vessel, 600 mg of sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 10 g of fluoropolyether both-terminal alcohol (manufactured by Solvay, Fomblin D2, 5.1 mmol) were added and heated and stirred at 70 ° C for 3 hours. The internal temperature was raised to 65 ° C, and 5.5 g of triethylene glycol-2-bromoethyl methyl ether (manufactured by Tokyo Chemical Industry Co., Ltd., 20.4 mmol) was dropped from the dropping funnel over 10 minutes, and the mixture was heated and stirred for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer and dried. The volatile matter was removed from the treated solution from which magnesium sulfate had been removed by filtration, and the solution was further dried at 100 ° C for 3 hours to obtain compound 1-1.

[0103] (Synthesis Example 2) Synthesis of tosylated polyethylene glycol monomethyl ether In a nitrogen-substituted reaction vessel, 8.0 g of polyethylene glycol monomethyl ether 400 (Tokyo Chemical Industry Co., Ltd., average molecular weight 380-420, 20.0 mmol), 25 mL of tetrahydrofuran (Tokyo Chemical Industry Co., Ltd.), and 4.7 g of p-toluenesulfonyl chloride (Tokyo Chemical Industry Co., Ltd., 25 mmol) were added and stirred until homogenous. A solution of 3.4 g of potassium hydroxide (FUJIFILM Wako Pure Chemical Industries, Ltd., 60 mmol) / 10 mL of pure water was added to a reaction vessel in an ice water bath, and after stirring for 10 minutes, the ice water bath was removed and the mixture was stirred at room temperature for 12 hours. The reaction solution was poured into a mixture of 30 mL of ice water / 60 mL of methylene chloride, and the aqueous layer was extracted three times with methylene chloride. 8 g of magnesium sulfate was added to the separated organic layer and dried. Volatiles were removed from the treated solution from which magnesium sulfate had been removed by filtration, and a tosylated polyethylene glycol monomethyl ether was obtained.

[0104] (Synthesis Example 3) Synthesis of Compound 1-2 Compound 1-2 was obtained by reacting the tosylated polyethylene glycol monomethyl ether synthesized in Synthesis Example 2 under the reaction conditions of Synthesis Example 1, instead of triethylene glycol-2-bromoethyl methyl ether.

[0105] (Synthesis Example 4) Synthesis of Compound 1-3 In a nitrogen-substituted reaction vessel, 600 mg of sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 7.7 g of fluoropolyether one-terminated alcohol (manufactured by Unichem Co., Ltd., perfluoropolyether modified product, molecular weight 1500, 5.1 mmol) were added and heated and stirred at 70 ° C for 3 hours. The internal temperature was set to 65 ° C, and 1.3 g (2.5 mmol) of the polyethylene glycol both-terminated tosylated product obtained in Synthesis Example 9 was dissolved in 5 g of 1,3-bis(trifluoromethyl)benzene and dropped from the dropping funnel over 10 minutes, and the mixture was heated and stirred for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer and dried. The magnesium sulfate was removed by filtration, and the volatile matter was distilled off from the treated solution. The solution was then dried at 100°C for 3 hours to obtain compound 1-3.

[0106] (Synthesis Example 5) Synthesis of Compound 1-4 In a nitrogen-substituted reaction vessel, 600 mg of sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 15.3 mmol), 30 g of 1,3-bis(trifluoromethyl)benzene (manufactured by Tokyo Chemical Industry Co., Ltd.), and 5.1 g of fluoropolyether one-terminated alcohol (manufactured by Unichem Co., Ltd., perfluoropolyether modified, molecular weight 1500, 5.1 mmol) were added and heated and stirred at 70 ° C for 3 hours. The internal temperature was set to 65 ° C, and 2.8 g of triethylene glycol-2-bromoethyl methyl ether (manufactured by Tokyo Chemical Industry Co., Ltd., 10.0 mmol) was dropped from the dropping funnel over 10 minutes, and the mixture was heated and stirred for 6 hours. After returning to room temperature, 5 ml of 1N hydrochloric acid was added to the reaction solution and stirred for 3 hours. This solution was washed four times with pure water, and 2 g of magnesium sulfate was added to the separated organic layer and dried. The volatile matter was removed from the treated solution from which magnesium sulfate had been removed by filtration, and the solution was further dried at 100 ° C for 3 hours to obtain compound 1-4.

[0107] (Synthesis Example 6) Synthesis of NpAF Trimethylneopentylammonium iodide was prepared by adding sodium carbonate (28.7 g) to an eggplant flask containing a magnetically stirred solution of methyl iodide (20 mL) and neopentylamine (11.8 mL) in ethanol (200 mL). After magnetic stirring at room temperature for over 20 hours, the mixture was suspended in ethanol (500 mL), filtered, and the solvent was removed on a hot stirrer. The resulting solid was then recrystallized from isopropanol (170 mL). The resulting crystals were dried in vacuum to obtain trimethylneopentylammonium iodide. The resulting trimethylneopentylammonium iodide (2 g), fluoride ion exchange resin (3.5 g), and methanol (30 mL) were placed in a PTFE beaker and allowed to stand for 30 minutes. After filtering the solution, the filtrate was kept at 60 °C on a hot stirrer to remove the solvent. After the solvent removal, a highly viscous solution was obtained. Isopropanol (6 mL) was added to the resulting solution, and the solution was dried in vacuum at 60°C to obtain brown crystals. The resulting crystals were transferred to a glove box, and after adding isopropanol (2 mL) in the glove box, the crystals were transferred to a sealable drying container and dried in vacuum at 60°C for one day and one night. The above drying procedure was repeated twice. The resulting crystals were transferred to a sealable drying container and dried in vacuum at 80°C for one day and one night to obtain white crystalline NpAF.

[0108] <Experiment 1> Examples 1 to 4, Comparative Examples 1 to 3 (Preparation of Electrolyte Composition Containing Fluoride Salt) Lithium fluoride (LiF, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added to the compounds shown in Table 1 and stirred at 45° C. for 24 hours to obtain a composition containing 5% by mass of fluoride salt. The obtained composition was pressure filtered using a membrane filter (DISMIC 25HP045AN) to obtain a sample for evaluation.

[0109] (Volatility test) Approximately 5 g of the sample was weighed into an aluminum cup and heated in a thermostatic chamber at 100° C. for 5 hours. The mass of the sample on the aluminum cup was then weighed, and the mass loss rate of the sample was calculated using the following formula. (Sample mass reduction rate) = 1 - (mass after heating) / (mass before heating) If the mass loss rate was 10% or less, it was rated as ◯ (low volatility), and if it was greater than 10%, it was rated as × (high volatility).

[0110] (Non-flammability test) The non-flammability (non-ignition property) of the composition was examined by the following method. (Sample preparation) A strip of cellulose paper (width 15 mm, length 320 mm, thickness 0.04 mm) was thoroughly immersed in the composition produced in the above Examples or Comparative Examples and then removed to prepare a sample. (Test Method) The sample was fixed on a metal stand, and a lighter flame was brought close to one end of the sample and held there for one second to check whether or not it ignited. The evaluation criteria were as follows: ◯ if the product did not ignite (non-flammable) or if it ignited but the fire went out immediately (self-extinguishing), and × if the product ignited and continued to burn.

[0111] (Ionic conductivity measurement) Ionic conductivity was measured at 25°C using a Mettler Toledo SevenCompact S230. The measuring device was calibrated in advance using a standard solution of 12.88 mS / cm.

[0112] [Table 1]

[0113] <Experiment 2> Examples 5 to 11 (Preparation of Electrolyte Composition Containing Fluoride Salt) Compound 1-1 and a fluoride salt shown in Table 2 were added so that the salt concentration was 5% by mass, and the mixture was stirred at 45° C. for 24 hours to obtain a composition. The obtained composition was pressure-filtered using a membrane filter (DISMIC 25HP045AN) to obtain a sample for evaluation.

[0114] The ionic conductivity, volatility, and non-flammability were evaluated in the same manner as in Experiment 1.

[0115] [Table 2] < / npaf> < / tbaf> < / tmaf> < / csf> < / kf> < / naf> < / lif>

Claims

1. Contains fluoropolyethers and fluoride salts, The electrolyte for a fluoride battery is at least one of the fluoropolyethers represented by the following formulas (1) to (3): (1) R 1 -O-Ra 1 -Rb 1 -O-Ra 1 -R 1 (2) R 2 -Rb 2 -O-Ra 2 -Rb 2 -R 2 (3) R 3 -Rb 3 -O-Ra 3 -R 3 (In the formula, Ra 1 to Ra 3 each independently represent a group containing an alkylene unit not containing fluorine and / or an oxyalkylene unit not containing fluorine, The oxyalkylene units of Ra 1 to Ra 3 are each independently —CH 2 CH 2 O— or —CH 2 CH(J)O—; Each J is independently an alkyl group or an aryl group; Rb 1 to Rb 3 each independently represent a fluoropolyether group represented by the following formula (5): R 1 to R 3 are each independently a hydrogen atom, a hydroxyl group, a fluorine atom, an alkyl group having 1 to 3 carbon atoms, an aryl group, or a fluoroalkyl group having 1 to 3 carbon atoms. (5) -Rf 1 -Rf-O-Rf 2 - (In the formula, Rf 1 and Rf 2 each independently represent an alkylene group having 1 to 16 carbon atoms which may be substituted by a fluorine atom, Rf is a divalent fluoropolyether group.

2. The Ra １ ~Ra ３ The electrolyte for a fluoride battery according to claim 1, wherein each of the groups independently represents a polyoxyalkylene group represented by the following formula (Ra-I): (Ra-I): -(CH ２ CH ２ O)r(CH ２ CH(CH ３ )O)s(CH ２ CH(CH ２ CH ３ )O)t(CH ２ CH(Ph)O)u- (In the formula, r, s, t, and u are each independently an integer of 0 or 1 or more, and r+s+t+u is 4 to 50.)

3. The Ra １ ~Ra ３ 3. The electrolyte for a fluoride battery according to claim 1 or 2, wherein the number average molecular weight of said electrolyte is 40 to 4,000.

4. 3. The electrolyte for a fluoride battery according to claim 1, wherein each Rf is independently a fluoropolyether group represented by the following formula (Rf-I): Formula (Rf-I): -(OC ６ F １２ )a-(OC ５ F １０ )b-(OC ４ F ８ )c-(OC ３ Rc ６ )d-(OC ２ F ４ )e-(OCF ２ )f- (In the formula, each Rc is independently a hydrogen atom, a fluorine atom, or a chlorine atom, a, b, c, d, e, and f each independently represent an integer from 0 to 200; the sum of a, b, c, d, e, and f is greater than or equal to 1; The order of each repeating unit to which a, b, c, d, e, or f is assigned is arbitrary; When all Rc's are hydrogen atoms or chlorine atoms, at least one of a, b, c, e and f is 1 or more.

5. The electrolyte for a fluoride battery according to claim 1 or 2, wherein each Rf is independently a group represented by the following formula (Rf-II) or the following formula (Rf-I-II): Formula (Rf-II): -(OC ３ F ６ )d-(OC ２ F ４ )e- (In the formula, d is an integer from 1 to 200, and e is 0 or 1.) Formula (Rf-I-II): -(OC ４ F ８ )c-(OC ３ F ６ )d-(OC ２ F ４ )e-(OCF ２ )f- (In the formula, c and d each independently represent an integer of 0 to 30, e and f each independently represent an integer from 1 to 200; the sum of c, d, e, and f is 2 or more; The order of the repeating units marked with c, d, e, or f is arbitrary.

6. The R １ ~R ３ 3. The electrolyte for a fluoride battery according to claim 1 or 2, wherein each of the groups independently represents a methyl group, an ethyl group, a trifluoromethyl group or a pentafluoroethyl group.

7. 3. The electrolyte for a fluoride battery according to claim 1, wherein the fluoride salt is ammonium fluoride or a metal fluoride.

8. 8. The electrolyte for a fluoride battery according to claim 7, wherein said ammonium fluoride is an alkylammonium fluoride having a neopentyl group.

9. 3. The electrolyte for a fluoride battery according to claim 1, wherein the content of the fluoride salt is 0.1 to 10 mass %.

10. 3. The electrolyte for a fluoride battery according to claim 1, which is liquid at 25°C.

11. Ion conductivity is 1.0 x 10 －９ ~1.0 x 10 －４ 3. The electrolyte for a fluoride battery according to claim 1, wherein the conductivity is 0.5 S / cm.

12. A polymer electrolyte comprising the electrolyte solution for a fluoride battery according to claim 1 or 2.

13. A fluoride battery comprising the electrolyte for a fluoride battery according to claim 1 or 2.

14. A fluoride battery comprising the polymer electrolyte of claim 12.

Images