Electrolytes for sodium-ion secondary batteries, sodium-ion secondary batteries, modules, and compounds

Abstract

Provided are an electrolyte for a sodium-ion secondary battery capable of improving the Coulomb efficiency, a sodium-ion secondary battery including the electrolyte, and a module. 【Solution means】An electrolyte for a sodium-ion secondary battery containing a compound represented by the following general formula (1). General formula (1): [Chemical formula 1] JPEG2026105854000111.jpg17156 (In the formula, R 101 and R 102 are each independently a substituent such as an alkyl group having 1 to 7 carbon atoms, and the substituent may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogens are fluorine, -SO2X 103 (X 103 is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, the case where both R 101 and R 102 are -H is excluded.)

Description

Technical Field

[0001] The present disclosure relates to an electrolyte for a sodium-ion secondary battery, a sodium-ion secondary battery, a module, and a compound.

Background Art

[0002] Patent Document 1 describes an electrolyte for a sodium-ion secondary battery containing sodium sulfamate (H2NSO3Na) and sodium bis(fluorosulfonyl)imide (NaFSI).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide an electrolyte for a sodium-ion secondary battery capable of improving the Coulomb efficiency, a sodium-ion secondary battery, and a module including the electrolyte. Another object of the present disclosure is to provide a novel compound.

Means for Solving the Problems

[0005] The present disclosure (1) is an electrolyte for a sodium-ion secondary battery containing a compound represented by the following general formula (1). General formula (1):

Chemical Formula

[0006] In the present disclosure (2), in the general formula (1), R 101 and R 102 are each independently<s -H, -F,<000091s>an alkyl group having 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, -SO2X 101 (X 101 (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, either -H, -F, or one or more hydrogen atoms.) -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R 101 and R 102 A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. This is the electrolyte for sodium-ion secondary batteries described in (1) of this disclosure.

[0007] This disclosure (3) includes R in the general formula (1) 101 and R 102 Each is independent of the others. -H, -F, Alkyl alkyl groups having 1 to 4 carbon atoms, Alkenyl groups with 2 to 4 carbon atoms, Alkynyl groups with 2 to 4 carbon atoms, -SO2X 101 (X 101 (This is an alkyl group having 1 to 4 carbon atoms, which may have -F or one or more hydrogen atoms substituted with fluorine.) -SO3X 102 (X 102 is an alkyl group which may have -F or one or more hydrogen atoms substituted with fluorine. ), or, R 101 and R 102A substituent that is a hydrocarbon group having 4 to 5 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more oxygen atoms in their structure, and one or more hydrogen atoms may be substituted with fluorine. This is an electrolyte for a sodium-ion secondary battery as described in (1) or (2) of this disclosure.

[0008] This disclosure (4) is that in the general formula (1) above, R 101 and R 102 Each is independent of the others. -H, -F, -CH3, -CH2CH3, -CH2CF3, -SO2F, -CH2CHCH2 -CH2CCH, -SO3CF3, R 101 and R 102 A group that combines with the nitrogen atom in general formula (1) to form a cyclic structure as -(CH2)5-, or R 101 and R 102 It is a group that combines with the nitrogen atom in general formula (1) to form a cyclic structure as -(CH2)2-O-(CH2)2-. This is an electrolyte for a sodium-ion secondary battery in any combination of any of (1) to (3) of the present disclosure.

[0009] Disclosure (5) is an electrolyte for a sodium-ion secondary battery in any combination of any of Disclosures (1) to (4) wherein the content of the compound represented by the general formula (1) is 10% by mass or less.

[0010] Disclosure (6) is an electrolyte for a sodium-ion secondary battery in any combination of any of Disclosures (1) to (5), wherein the content of the compound represented by the general formula (1) is 0.0001% by mass or more.

[0011] The present disclosure (7) is an electrolyte for a sodium-ion secondary battery in any combination of any one of the present disclosures (1) to (6) in which the content of the compound represented by the general formula (1) is 0.05 to 2% by mass.

[0012] The present disclosure (8) is an electrolyte for a sodium-ion secondary battery in any combination of any one of the present disclosures (1) to (7) containing at least one selected from the group consisting of NaPF6 and sodium bis(fluorosulfonyl)imide.

[0013] The present disclosure (9) is an electrolyte for a sodium-ion secondary battery in any combination of any one of the present disclosures (1) to (8) containing sodium bis(fluorosulfonyl)imide.

[0014] The present disclosure (10) is an electrolyte for a sodium-ion secondary battery in any combination of any one of the present disclosures (1) to (9) containing at least one solvent selected from the group consisting of carbonate and carboxylic acid ester.

[0015] The present disclosure (11) is a sodium-ion secondary battery including an electrolyte in any combination of any one of the present disclosures (1) to (10).

[0016] The present disclosure (12) is a module including the sodium-ion secondary battery described in the present disclosure (11).

[0017] <00009​​​​​​​​​​​​​​​​​​​​​​​​​​​​​103 and R 104 These are groups represented by ), where one or more hydrogens may be substituted with fluorine, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, where one or more hydrogens may be substituted with fluorine, n101 is an integer of 0 or more, and p101 is 0 or 1. Alkyl alkyl groups with 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups with 6 to 15 carbon atoms, -SO2X 101 (X 101 (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, either -H, -F, or one or more hydrogen atoms.) -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R 201 and R 202 A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 (is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, R 201 and R 202 If both are -H, then R 201 and R 202 If both are -CH3, and R 201 and R 202 (Except when one of them is -H and the other is a cyclohexyl group.)

[0018] This disclosure (14) includes R in the general formula (1-1) 201 and R 202These are all compounds described in disclosure (13) that are -CH2CH3. [Effects of the Invention]

[0019] This disclosure provides an electrolyte for sodium-ion secondary batteries that can improve Coulomb efficiency, as well as a sodium-ion secondary battery and module equipped with the electrolyte. It also provides novel compounds. [Modes for carrying out the invention]

[0020] The following provides a detailed explanation of this disclosure.

[0021] This disclosure relates to an electrolyte for a sodium-ion secondary battery (hereinafter also referred to as the electrolyte of this disclosure) containing a compound represented by the following general formula (1) (hereinafter also referred to as compound (1)). General formula (1): [ka] (In the formula, R 101 and R 102 Each is independent of the others. -H, -F, Formula:-O p101 -(SiR 103 20) n101 -SiR 104 3(R 103 and R 104 These are groups represented by ), where one or more hydrogens may be substituted with fluorine, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, where one or more hydrogens may be substituted with fluorine, n101 is an integer of 0 or more, and p101 is 0 or 1. Alkyl alkyl groups with 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups with 6 to 15 carbon atoms, -SO2X101 (X 101 is -H, -F, or an alkyl group in which one or more hydrogens may be substituted with fluorine.). -SO3X 102 (X 102 is -H, -F, or an alkyl group in which one or more hydrogens may be substituted with fluorine.), or R 101 and R 102 which is a substituent that forms a cyclic structure together with the nitrogen atom in the general formula (1) and may contain a multiple bond, and is a hydrocarbon group having 2 to 7 carbon atoms, the substituent may contain one or more divalent to hexavalent heteroatoms in their structure, and one or more hydrogens may be substituted with fluorine, -SO2X 103 (X 103 is -H or -F.). or may be substituted with a functional group having 1 to 8 carbon atoms. However, the case where both R 101 and R 102 are -H is excluded.).

[0022] Since the electrolytic solution of the present disclosure contains a specific sodium sulfamate compound, the Coulomb efficiency of a sodium ion secondary battery can be improved. This effect is considered to be due to the fact that when R 101 and R 102 are specific substituents, the S-N bond in the general formula (1) is broken in the electrolytic solution, and a good film is formed on the electrode by the decomposition products. R 101 and R 102 If both are -H, the polarization on the compound changes, the H-N-H site becomes more unstable than the S-N bond, and H is likely to desorb, making it difficult to form a good film by the decomposition products with the S-N bond broken as described above.

[0023] In the general formula (1), the above substituent is -H, -F, the above formula: -O p101 -(SiR y 103 2O) n101 -SiR 104 3, the above alkyl group, the above alkenyl group, the above alkynyl group, the above aryl group, the above -SO2X101 , the above -SO3X 102 , or represents the above hydrocarbon group. The above substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogens may be fluorine, -SO2X 103 (X 103 is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms.

[0024] Examples of the heteroatoms that the above substituents may contain include an oxygen atom (O), a sulfur atom (S), a nitrogen atom (N), a silicon atom (Si), a phosphorus atom (P), a boron atom (B), etc. More preferably, it is an oxygen atom, a sulfur atom or a nitrogen atom.

[0025] The carbon number of the functional group that the above substituents may have is 1 to 8, preferably 1 to 7, and more preferably 1 to 4.

[0026] Examples of the functional group that the above substituents may have include, for example, a phenyl group, an anisyl group, a benzyl group, a cyano group, a trialkylsilyl group (the alkyl group preferably has 1 to 4 carbon atoms. However, the total carbon number of the three alkyl groups is 8 or less.), -SO2X 104 (X 104 is an alkyl group having 1 to 8 carbon atoms (preferably 1 to 7 carbon atoms, more preferably 1 to 4 carbon atoms) in which one or more hydrogens may be substituted with fluorine.), an alkyl group having 1 to 8 carbon atoms (preferably 1 to 7 carbon atoms, more preferably 1 to 4 carbon atoms) in which one or more hydrogens may be substituted with fluorine, a saturated heterocyclic group having 1 to 8 carbon atoms (preferably 1 to 7 carbon atoms, more preferably 1 to 4 carbon atoms), or an alkoxy group having 1 to 8 carbon atoms (preferably 1 to 7 carbon atoms, more preferably 1 to 4 carbon atoms) is preferred.

[0027] The above R 101 and R 102The alkyl group may be linear, branched, or cyclic. The number of carbon atoms is 1 to 7, but preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, and even more preferably 2 or less. The alkyl group may be a fluoroalkyl group in which the hydrogen atoms bonded to the carbon atoms are substituted with fluorine, or the hydrogen atoms bonded to the carbon atoms may be the above-mentioned -SO2X 103 Alternatively, it may be substituted with a functional group having 1 to 8 carbon atoms. The above R 101 and R 102 The alkyl group is preferably a C1-C7 alkyl group in which one or more hydrogens may be substituted with fluorine, preferably a C1-C4 alkyl group in which one or more hydrogens may be substituted with fluorine, preferably a C1-C2 alkyl group in which one or more hydrogens may be substituted with fluorine, and more preferably an ethyl group in which one or more hydrogens may be substituted with fluorine.

[0028] The above R 101 and R 102 The alkenyl group may be linear, branched, or cyclic. The number of carbon atoms is 2 to 7, but preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. The alkenyl group may be a fluoroalkylene group in which the hydrogen atoms bonded to the carbon atoms are substituted with fluorine, or the hydrogen atoms bonded to the carbon atoms may be the above-mentioned -SO2X 103 Alternatively, it may be substituted with a functional group having 1 to 8 carbon atoms.

[0029] The above R 101 and R 102 The alkynyl group may be linear, branched, or cyclic. The number of carbon atoms is 2 to 7, but preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. The alkynyl group may be a fluoroalkynyl group in which the hydrogen atoms bonded to the carbon atoms are substituted with fluorine, or the hydrogen atoms bonded to the carbon atoms may be the above-mentioned -SO2X 103 Alternatively, it may be substituted with a functional group having 1 to 8 carbon atoms.

[0030] The above R 101 and R 102The aryl group preferably has 6 to 7 carbon atoms. The aryl group may be a fluoroaryl group in which the hydrogen atom bonded to the carbon is substituted with fluorine, or the hydrogen atom bonded to the carbon may be the above-mentioned -SO2X 103 Alternatively, it may be substituted with a functional group having 1 to 8 carbon atoms.

[0031] The above R 101 and R 102 The formula is: -O p101 -(SiR 103 20) n101 -SiR 104 3(R 103 and R 104 These may be groups represented by (1) an alkyl group in which one or more hydrogens may be substituted with fluorine, an alkenyl group in which one or more hydrogens may be substituted with fluorine, an alkynyl group in which one or more hydrogens may be substituted with fluorine, or an aryl group in which one or more hydrogens may be substituted with fluorine, where n101 is an integer of 0 or more, and p101 is 0 or 1. The above R 103 and R 104 In this, the alkyl group, in which one or more hydrogens may be substituted with fluorine, preferably has 1 to 10 carbon atoms, more preferably 1 to 7, and even more preferably 1 to 4 carbon atoms. Alkenyl groups and alkynyl groups, in which one or more hydrogen atoms may be substituted with fluorine, preferably have 2 to 10 carbon atoms, more preferably 2 to 7, and even more preferably 2 to 4 carbon atoms. The aryl group, in which one or more hydrogen atoms may be substituted with fluorine, preferably has 6 to 8 carbon atoms, and more preferably 6 to 7 carbon atoms. In the above formula, n101 is an integer greater than or equal to 0, preferably less than or equal to 2000, more preferably an integer between 0 and 100, and even more preferably between 0 and 10.

[0032] The above R 101 and R 102 is, -SO2X 101 (X 101is an alkyl group which may have one or more hydrogen atoms substituted with fluorine. ) The above -SO2X 101 The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 4. X 101 As such, -F or the above alkyl group is preferred, and -F is more preferred.

[0033] The above R 101 and R 102 is, -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or -H, -F, or ). The above -SO3X 102 The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 4. X 102 As such, -F or the above alkyl group is preferred, and -F is more preferred.

[0034] The above R 101 and R 102Specifically, these include: linear alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl, i-pentyl, neopentyl, sec-pentyl, 3-pentyl, tert-pentyl, and hexyl; cyclic alkyl groups such as cyclopentyl, cyclohexyl, norbornanyl, and 1-adamantyl; alkenyl groups such as vinyl, 1-propenyl, 2-propenyl (allyl), 2-butenyl, and 1,3-butadienyl; alkynyl groups such as ethynyl, 1-propynyl, 2-propynyl, and 2-butynyl; trifluoromethyl, 2,2,2-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, pentafluoroethyl, and 2,2,3,3,3-pentafluoroethyl. Examples of halogenated alkyl groups include ruolopropyl group, 1,1,2,3,3,3-hexafluoropropyl group, and heptafluoropropyl group; halogenated alkenyl group, such as 1-fluorovinyl group and 2-fluoroallyl group; alkyl groups having functional groups such as cyanomethyl group, and alkyl groups having saturated heterocyclic groups such as 3-pyrrolidinopropyl group; aryl groups such as phenyl group, which may have alkyl substituents, alkoxy substituents, etc.; aralkyl groups such as phenylmethyl group and phenylethyl group; trialkylsilyl group, such as trimethylsilyl group; trialkylsiloxy group, such as trimethylsiloxy group; sulfonyl group, such as fluorosulfonyl group, trifluoromethanesulfonyl group, and pentafluoroethanesulfonyl group; and sulfonic acid group, such as methylsulfonic acid group. However, the examples are not limited to these.

[0035] Also, R 101 and R 102 If it is a hydrocarbon group that forms a cyclic structure by bonding, then the number of carbon atoms (R 101 and R 102 The total number of carbon atoms (including the carbon atoms) is 2 to 7, but is preferably 6 or less, more preferably 5 or less, and more preferably 3 or more, and more preferably 4 or more. R 101 and R 102 When they bond to form a cyclic structure, for example, the nitrogen atom (N) in general formula (1) and R 101 and R 102Preferably, the group forms a 5-membered or 6-membered ring, and may form a cyclic amino group such as a pyrrolidino group or a piperidino group, or it may form a heterocyclic amino group such as a 4-morpholino group, succinimidyl group, or maleimidyl group containing a heteroatom. In these cases, one or more hydrogens bonded to the carbon may be substituted with fluorine, or the hydrogens bonded to the carbon may be the above-mentioned -SO2X 103 Alternatively, it may be substituted with a functional group having 1 to 8 carbon atoms. Furthermore, it may contain double or triple bonds in the cyclic structure. R 101 and R 102 When these groups bond to form a cyclic structure, the hydrocarbon group is preferably one having 4 to 5 carbon atoms, more preferably -(CH2)4-, -(CH2)5-, or -(CH2)2-O-(CH2)2-, and even more preferably -(CH2)5- or -(CH2)2-O-(CH2)2-.

[0036] In the above general formula (1), R 101 and R 102 Both cannot be -H. 101 and R 102 In all cases, it is preferable that the substituents are other than -H among the substituents mentioned above.

[0037] In the above general formula (1), R 101 and R 102 These are independently -H, -F, an alkyl group having 1 to 7 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, an alkynyl group having 2 to 7 carbon atoms, and -SO2X. 101 (X 101 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, -H, -F, or -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, -H, -F, or R 101 and R 102A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1) and may contain multiple bonds (each substituent may contain one or more 2-6 valent heteroatoms in its structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 It is preferably -H or -F (or may be substituted with a functional group having 1 to 8 carbon atoms), and is preferably -H, -F, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkynyl group having 2 to 4 carbon atoms, or -SO2X 101 (X 101 (-F, or a C1-C4 alkyl group in which one or more hydrogen atoms may be substituted with fluorine.), -SO3X 102 (X 102 is an alkyl group which may have one or more hydrogen atoms substituted with fluorine. ), or R 101 and R 102 It is more preferable that the substituents are C4-C5 hydrocarbon groups that form a cyclic structure with the nitrogen atom in general formula (1) and may contain multiple bonds (each substituent may contain one or more oxygen atoms in its structure, and one or more hydrogens may be substituted with fluorine), and are -H, -F, -CH3, -CH2CH3, -CH2CF3, -SO2F, -CH2CHCH2, -CH2CCH, -SO3CF3, R 101 and R 102 A group that combines with the nitrogen atom in general formula (1) to form a cyclic structure as -(CH2)5-, or R 101 and R 102 It is even more preferable that the group is bonded to form a cyclic structure with the nitrogen atom in general formula (1) as -(CH2)2-O-(CH2)2-.

[0038] In the above general formula (1), R 101 and R 102 Each of these is independently -H, an alkyl group having 1 to 7 carbon atoms, and -SO2X 101 (X 101 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, -H, -F, or R 101 and R102 A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1) and may contain multiple bonds (each substituent may contain one or more 2-6 valent heteroatoms in its structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 is -H or -F. (It may also be substituted with a functional group having 1 to 8 carbon atoms), and may be -H, an alkyl group having 1 to 4 carbon atoms, or -SO2X 101 (X 101 is -F, or a C1-C4 alkyl group in which one or more hydrogens may be substituted with fluorine. ), or R 101 and R 102 The substituents may be C4-C5 hydrocarbon groups that form a cyclic structure with the nitrogen atom in general formula (1) and may also contain multiple bonds (each substituent may contain one or more oxygen atoms in its structure, and one or more hydrogens may be substituted with fluorine), such as -H, -CH3, -CH2CH3, -CH2CF3, -SO2F, R 101 and R 102 A group that combines with the nitrogen atom in general formula (1) to form a cyclic structure as -(CH2)5-, or R 101 and R 102 It may also be a group that combines with the nitrogen atom in general formula (1) to form a cyclic structure as -(CH2)2-O-(CH2)2-. Also, R 101 and R 102 Preferably, at least one of them is -CH2CH3, R 101 and R 102 It is particularly preferable that both are -CH2CH3.

[0039] As an example of compound (1), the compound represented by the following formula can be cited. [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0040] In this specification, Me represents a methyl group (CH3), Et represents an ethyl group (CH2CH3), n-Pr represents a n-propyl group, i-Pr represents an isopropyl group, n-Bu represents a n-butyl group, i-Bu represents an iso-butyl group, s-Bu represents a sec-butyl group, t-Bu represents a tert-butyl group, TMS represents a trimethylsilyl group, and TBDMS represents a tert-butyldimethylsilyl group. Furthermore, when described as follows, R may be bonded to any carbon atom constituting the benzene ring, for example, R may be located at any of the o-, m-, or p- positions. [ka] Furthermore, the examples of compounds described herein include geometric isomers of those compounds (if any) and are not limited to the specific examples provided.

[0041] Among the compounds (1), the compound represented by the following formula is preferred. [ka]

[0042] As compound (1), the compound represented by the following formula is more preferred. [ka]

[0043] Compound (1) may be a compound represented by the following formula. [ka]

[0044] Compound (1) may be a compound represented by the following formula. [ka]

[0045] Compound (1) is particularly preferred if it is represented by the following formula. [ka]

[0046] Among the compounds (1), the compound represented by the following general formula (1-1) (hereinafter also referred to as compound (1-1)) is a novel compound. This disclosure also relates to compound (1-1). General formula (1-1): [ka] (In the formula, R 201 and R 202 Each is independent of the others. -H, -F, Formula:-O p101 -(SiR 10320) n101 -SiR 104 3(R 103 and R 104 These are groups represented by ), where one or more hydrogens may be substituted with fluorine, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, where one or more hydrogens may be substituted with fluorine, n101 is an integer of 0 or more, and p101 is 0 or 1. Alkyl alkyl groups with 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups with 6 to 15 carbon atoms, -SO2X 101 (X 101 (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, either -H, -F, or one or more hydrogen atoms.) -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R 201 and R 202 A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 (is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, R 201 and R 202 If both are -H, then R 201 and R 202 If both are -CH3, and R 201 and R 202 (Except when one of them is -H and the other is a cyclohexyl group.)

[0047] In general formula (1-1), R 201 and R202 It is not possible for both to be -H, R 201 and R 202 Neither of them becomes -CH3, R 201 and R 202 One of them will not be -H and the other a cyclohexyl group. 201 and R 202 In all cases, it is preferable that the substituents are other than -H among the substituents mentioned above. R in general formula (1-1) 201 and R 202 As above -O p101 -(SiR 103 20) n101 -SiR 104 3. The alkyl group, the alkenyl group, the alkynyl group, the aryl group, the -SO2X 101 , the above-SO3X 102 And the hydrocarbon group mentioned above is R in general formula (1). 101 and R 102 Similar examples include the above.

[0048] In the above general formula (1-1), R 201 and R 202 Each of these is independently -H, an alkyl group having 1 to 7 carbon atoms, and -SO2X 101 (X 101 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, -H, -F, or R 201 and R 202 A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1) and may contain multiple bonds (each substituent may contain one or more 2-6 valent heteroatoms in its structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 It is preferably -H or -F (or may be substituted with a functional group having 1 to 8 carbon atoms), and is preferably -H, an alkyl group having 1 to 4 carbon atoms, or -SO2X 101 (X 101 is -F, or a C1-C4 alkyl group in which one or more hydrogens may be substituted with fluorine. ), or R 101 and R102 It is more preferable that the substituents are C4-C5 hydrocarbon groups that form a cyclic structure with the nitrogen atom in general formula (1) and may contain multiple bonds (each substituent may contain one or more oxygen atoms in its structure, and one or more hydrogens may be substituted with fluorine), and are -H, -CH2CH3, -CH2CF3, -SO2F, R 201 and R 202 A group that combines with the nitrogen atom in general formula (1-1) to form a cyclic structure as -(CH2)5-, or R 201 and R 202 It is even more preferable that the group is bonded to form a cyclic structure with the nitrogen atom in general formula (1-1) as -(CH2)2-O-(CH2)2-. Also, R 201 and R 202 Preferably, at least one of them is -CH2CH3, R 201 and R 202 It is particularly preferable that both are -CH2CH3.

[0049] Among the compounds (1-1), the compound represented by the following formula is preferred. [ka]

[0050] As compound (1-1), the compound represented by the following formula is more preferred. [ka]

[0051] As compound (1-1), the compound represented by the following formula is particularly preferred. [ka]

[0052] Compound (1-1) can be used not only as an electrolyte component but also as a functional compound such as a pharmaceutical intermediate, surfactant, or food additive.

[0053] Compound (1) (including compound (1-1)) is, for example, defined by the following general formula (a): [ka] (In the formula, X 111 Compound (a) represented by (where is fluorine, chlorine, bromine, or iodine) and the following general formula (b): [ka] (In the formula, R 101 and R 102 The above is the same. The compound can be suitably produced by a manufacturing method (hereinafter also referred to as the first manufacturing method) which includes step (1) of reacting compound (b) represented by ) with compound (b) represented by general formula (1) to obtain compound (1) represented by general formula (1).

[0054] X in general formula (a) 111 The raw material is fluorine, chlorine, bromine, or iodine, and chlorine is preferred from the viewpoint of the availability of the raw material compound and its reactivity.

[0055] A specific example of compound (b) would be a primary amine. [ka] These are some examples, If it's a secondary amine, [ka] [ka] These are some examples.

[0056] The amount of compound (b) used in step (1) is preferably 0.8 molar times or more, more preferably 1.0 molar time or more, and even more preferably 1.1 molar times or more, relative to compound (a). There is no particular upper limit, but it is usually 3.0 molar times or less, preferably 2.5 molar times or less, and more preferably 2.2 molar times or less.

[0057] The reaction in step (1) is preferably carried out in the presence of a base (excluding compound (b) above). Examples of such bases include amines (excluding compound (b) above) and inorganic bases. Examples of the above-mentioned amines include triethylamine, tri(n-propyl)amine, tri(n-butyl)amine, diisopropylethylamine, cyclohexyldimethylamine, pyridine, lutidine, γ-collidine, N,N-dimethylaniline, N-methylpiperidine, N-methylpyrrolidine, N-methylmorpholine, 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1,5-diazabicyclo[4.3.0]-5-nonene, 1,4-diazabicyclo[2.2.2]octane (DABCO), 4-dimethylaminopyridine (DMAP), proton sponge, and the like. Examples of the inorganic bases mentioned above include lithium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, cesium carbonate, cesium bicarbonate, lithium bicarbonate, cesium fluoride, potassium fluoride, sodium fluoride, lithium chloride, lithium bromide, and the like. Among the above bases, the above amines are preferred. Among the above amines, triethylamine or pyridine is preferred. The above-mentioned base may be a solid or a liquid at room temperature. If it is a solid, it can be used after being dissolved in a solvent.

[0058] When the above base is used in combination, the total amount of the above base and compound (b) used is preferably 2.0 molar times or more, more preferably 2.1 molar times or more, and even more preferably 2.2 molar times or more, relative to the amount of compound (a) used. There is no particular upper limit, but it is usually 5.0 molar times or less, preferably 4.5 molar times or less, and more preferably 4.0 molar times or less. In this case, the ratio of the above base to compound (b) is preferably in the range of base:compound (b) 0.01:0.99 to 0.60:0.40, more preferably in the range of 0.40:0.60 to 0.55:0.45, and even more preferably in the range of 0.45:0.55 to 0.50:0.50.

[0059] The temperature in step (1) is not limited as long as the above reaction proceeds, but for example, it is preferably 100°C or lower, more preferably 50°C or lower, and even more preferably 30°C or lower. Also, it is preferably -50°C or higher, more preferably -30°C or higher, and even more preferably -10°C or higher. At the above temperatures, side reactions are less likely to occur, and the reaction can proceed efficiently.

[0060] The reaction in step (1) can be carried out in a solvent. A non-aqueous solvent is preferred as the solvent. For example, a non-aqueous solvent that has low reactivity with compounds (a) and (b) is preferred. Furthermore, a non-aqueous solvent in which compounds (a) and (b) dissolve is preferred. For example, the solubility of compound (a) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. Furthermore, the solubility of compound (b) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. Furthermore, since it is less likely to remain on the target compound (1), the boiling point of the above solvent is preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 150°C or lower at normal pressure.

[0061] Specifically, the above solvents include: linear esters such as methyl acetate, ethyl acetate, ethyl methanesulfonate, and methyl ethanesulfonate; linear carbonate esters such as dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; cyclic carbonate esters such as ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; linear carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, and carbon tetrachloride; linear ethers such as diethyl ether, ethyl methyl ether, tert-butyl methyl ether, and dimethoxyethane; cyclic ethers such as tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane; linear nitriles such as acetonitrile and propionitrile; and further, lactones, ketones, aldehydes, amides, and hydrocarbon solvents. From the viewpoint of compatibility with compound (a) and compound (b), boiling point, and availability, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, acetonitrile, dichloromethane, or chloroform are preferred, with dimethyl carbonate and acetonitrile being more preferred. These non-aqueous solvents may be used individually or in combination. In addition, any protic solvent that does not react with compound (a), compound (b), and compound (1), such as higher alcohols, can be used.

[0062] The ratio of the non-aqueous solvent to compound (a) in step (1) is not particularly limited, but for example, a weight ratio of 100 times or less is preferred, more preferably 50 times or less, and even more preferably 25 times or less. Also, a weight ratio of 2 times or more is preferred, more preferably 3 times or more, and even more preferably 5 times or more. When the ratio is within the above range, unreacted compound (a) is less likely to precipitate, and the product can be manufactured more easily.

[0063] Step (1) may be, for example, a method of adding compound (a) dropwise while stirring a solution of compound (b), or a method of adding compound (b) dropwise to a solution of compound (a). When adding compound (a) or compound (2) dropwise, compound (a) or compound (b) may be diluted.

[0064] The first manufacturing method further comprises general formula (c): [ka] (In the formula, X 111 A compound (c) represented by (where is fluorine, chlorine, bromine, or iodine) is reacted with a sodium source to produce the following general formula (a): [ka] (In the formula, X 111 The step (2) may also include obtaining a compound (a) represented by fluorine, chlorine, bromine, or iodine.

[0065] X in general formula (c) 111 The compound (c) is fluorine, chlorine, bromine, or iodine, and chlorine is preferred from the viewpoint of the availability and reactivity of the raw material compound (c).

[0066] The sodium source in step (2) is preferably sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium hydride, n-butylsodium, sec-butylsodium, tert-butylsodium, sodium hydroxide, or metallic sodium, more preferably sodium fluoride, sodium chloride, sodium bromide, or sodium iodide, and even more preferably sodium chloride.

[0067] The amount of sodium source used in step (2) is preferably 1.5 molar times or less, more preferably 1.2 molar times or less, and even more preferably 1.0 molar time or less relative to compound (c). The lower limit is not particularly limited, but is usually 0.50 molar times or more, preferably 0.80 molar times or more, and more preferably 0.90 molar times or more.

[0068] The temperature in step (2) is not limited as long as the above reaction proceeds, but for example, 150°C or lower is preferred, 120°C or lower is more preferred, and 90°C or lower is even more preferred. Also, -20°C or higher is preferred, 0°C or higher is more preferred, and 20°C or higher is even more preferred. At the above temperatures, side reactions are less likely to occur, and the reaction can proceed efficiently.

[0069] The reaction in step (2) can be carried out in the absence of a solvent, but it can also be carried out in a solvent. The solvent used is not particularly limited as long as it is a non-aqueous solvent, and it is more preferably an aprotic solvent. For example, an aprotic solvent that has low reactivity with compound (c) is preferred. Furthermore, an aprotic solvent in which compound (c) dissolves is preferred. For example, the solubility of compound (c) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. Furthermore, since it is less likely to remain on the target compound (1), the boiling point of the above solvent is preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 150°C or lower at normal pressure.

[0070] Specifically, the above solvents include: linear esters such as methyl acetate, ethyl acetate, ethyl methanesulfonate, and methyl ethanesulfonate; linear carbonate esters such as dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; cyclic carbonate esters such as ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; linear carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, and carbon tetrachloride; linear ethers such as diethyl ether, ethyl methyl ether, tert-butyl methyl ether, and dimethoxyethane; cyclic ethers such as tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane; linear nitriles such as acetonitrile and propionitrile; and further, lactones, ketones, aldehydes, amides, and hydrocarbon solvents. From the viewpoint of compatibility with compound (c) and sodium sources, boiling point, and availability, dimethyl carbonate, ethylmethyl carbonate, or diethyl carbonate, acetonitrile, dichloromethane, or chloroform are preferred, with dimethyl carbonate and acetonitrile being more preferred. These non-aqueous solvents may be used individually or in combination. In addition, any protic solvent that does not react with compound (c) or compound (a), such as higher alcohols, can be used.

[0071] In step (2), the ratio of the non-aqueous solvent to compound (c) is not particularly limited, but for example, a volume ratio of 100 times or less is preferred, more preferably 50 times or less, and even more preferably 25 times or less. Also, a volume ratio of 1 time or more is preferred, more preferably 3 times or more, and even more preferably 5 times or more. When the ratio is within the above range, the resulting compound (c) is less likely to precipitate and can be manufactured more easily.

[0072] Step (2) may be carried out by adding a sodium source while stirring a solution of compound (c), or by adding compound (c) dropwise while dissolving or suspending the sodium source in a solvent. If added dropwise, compound (c) may be diluted. If no solvent is present, the sodium source may be added to compound (c), or compound (c) may be added to the sodium source. The sodium source may be used as an element or as a solution.

[0073] In the first manufacturing method, step (2) is performed before step (1). Between step (2) and step (1), there may be a step of recovering compound (a) obtained in step (2) from the solvent, and further a purification step such as recrystallization may be included. If steps (2) and (1) are carried out consecutively in the same solvent, the recovery and purification steps described above are unnecessary.

[0074] Furthermore, the first manufacturing method may include a step after step (1) in which the compound (1) obtained in step (1) is recovered from the solvent, and may also include a purification step such as pH adjustment or recrystallization.

[0075] Compound (1) (including compound (1-1)) has the general formula (c): [ka] (In the formula, X 111 Compounds represented by (c) (where is fluorine, chlorine, bromine, or iodine) and general formula (d): [ka] (In the formula, R 101 and R 102 The compound can also be suitably produced by a manufacturing method (hereinafter also referred to as the second manufacturing method) which includes step (3) of reacting compound (d) represented by the same formula as above with compound (d) to obtain compound (1) represented by general formula (1).

[0076] X in general formula (c) 111The compound (c) is fluorine, chlorine, bromine, or iodine, and chlorine is preferred from the viewpoint of the availability and reactivity of the raw material compound (c).

[0077] The above R 101 and R 102 Examples include the same compounds as those described above (b) and (1), and it is preferable that the substituent has an electron-withdrawing substituent in that it reduces the basicity of compound (d) and the heat of reaction with compound (c). Particularly preferred electron-withdrawing substituents are fluorinated alkyl groups, fluorinated alkenyl groups, fluorinated alkynyl groups, sulfonyl groups, cyano groups, or cyanomethyl groups.

[0078] Examples of electron-withdrawing groups include, but are not limited to, trifluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, 2,2,3,3,3-pentafluoropropyl, heptafluoropropyl, fluorosulfonyl, trifluoromethanesulfonyl, 2,2,2-trifluoroethanesulfonyl, pentafluoroethanesulfonyl, 2,2,3,3,3-pentafluoropropanesulfonyl, heptafluoropropanesulfonyl, cyano, and cyanomethyl groups.

[0079] A specific example of compound (d) is: [ka] These are some examples.

[0080] The amount of compound (d) used in step (3) is preferably 0.7 molar times or more, more preferably 0.8 molar times or more, and even more preferably 0.9 molar times or more, relative to compound (c). There is no particular upper limit, but it is usually 2.0 molar times or less, preferably 1.5 molar times or less, and more preferably 1.1 molar times or less.

[0081] The temperature in step (3) is not limited as long as the above reaction proceeds, but for example, it is preferably 200°C or lower, more preferably 170°C or lower, and even more preferably 150°C or lower. Also, it is preferably 0°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher. At the above temperatures, the reaction can proceed efficiently.

[0082] The reaction in step (3) can be carried out in a solvent. A non-aqueous solvent is preferred as the solvent. For example, a non-aqueous solvent that has low reactivity with compound (c), compound (d), and compound (1) is preferred. Furthermore, a non-aqueous solvent in which compounds (c) and (d) dissolve is preferred. For example, the solubility of compound (c) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. Furthermore, the solubility of compound (d) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. Furthermore, since it is less likely to remain in the resulting sodium sulfamate compound, the boiling point of the solvent is preferably 300°C or lower, more preferably 200°C or lower, and even more preferably 150°C or lower at atmospheric pressure.

[0083] Specifically, the above solvents include: chain esters such as methyl acetate, ethyl acetate, ethyl methanesulfonate, and methyl ethanesulfonate; chain carbonate esters such as dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; cyclic carbonate esters such as ethylene carbonate, propylene carbonate, and fluoroethylene carbonate; chain carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, and carbon tetrachloride; chain ethers such as diethyl ether, ethyl methyl ether, tert-butyl methyl ether, and dimethoxyethane; cyclic ethers such as tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane; chain nitriles such as acetonitrile and propionitrile; and further, lactones, ketones, aldehydes, amides, and hydrocarbon solvents. From the viewpoint of compatibility between compound (c) and compound (d), boiling point, and availability, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, acetonitrile, or diethyl ether are preferred, and dimethyl carbonate, acetonitrile, or diethyl ether are more preferred. These non-aqueous solvents may be used alone or in combination. In addition, any protic solvent that does not react with compound (c), compound (d), and compound (1), such as higher alcohols, can be used.

[0084] The ratio of the non-aqueous solvent to compound (c) in step (3) is not particularly limited, but for example, a volume ratio of 100 times or less is preferred, more preferably 50 times or less, and even more preferably 25 times or less. Also, a volume ratio of 1 time or more is preferred, more preferably 3 times or more, and even more preferably 5 times or more. If it is within the above range, side reactions are less likely to proceed, and the product can be manufactured more easily.

[0085] Step (3) may be, for example, a method of adding compound (d) dropwise while stirring a solution of compound (c), or a method of adding compound (c) dropwise to a solution of compound (d). When adding compound (c) or compound (d) dropwise, compound (c) or compound (d) may be diluted.

[0086] The second manufacturing method may include, after step (3), a step of recovering the compound (1) obtained in step (3) from the solvent, and may further include a purification step such as pH adjustment or recrystallization.

[0087] Compound (1) (including compound (1-1)) is given by the following general formula (e): [ka] (In the formula, Z 101 is fluorine, chlorine, bromine, or iodine, and R 101 and R 102 The above is the same.) The compound (e) represented by ) is reacted with water to form the following general formula (f): [ka] (In the formula, R 101 and R 102 The compound can also be suitably produced by a manufacturing method (hereinafter also referred to as the third manufacturing method) which includes a step (4) of obtaining a compound (f) represented by the same formula as above, and a step (5) of reacting the compound (f) represented by the general formula (f) with a sodium source to obtain a compound (1) represented by the general formula (1).

[0088] In general formulas (e) and (f), R 101 and R 102 This is the same as the first and second manufacturing methods described above.

[0089] In general formula (e), Z 101 The element is fluorine, chlorine, bromine, or iodine, and chlorine is preferred.

[0090] Step (4) described above can be carried out, for example, by introducing water into the reaction vessel and adding the compound represented by general formula (e) to the introduced water. The amount of water is not particularly limited, and it is sufficient to use at least 1 equivalent in molar ratio to compound (e). Ice may also be added to make ice water.

[0091] The temperature in step (4) above is not limited as long as the reaction proceeds, but it is preferable to carry it out at, for example, 0 to 20°C.

[0092] The sodium source in step (5) is preferably sodium hydroxide, sodium hydride, or metallic sodium, with sodium hydroxide being more preferred.

[0093] The amount of sodium source used in step (5) is preferably 1.5 molar times or less relative to compound (f), more preferably 1.2 molar times or less, and even more preferably 1.1 molar times or less. The lower limit is not particularly limited, but is usually 0.50 molar times or more, preferably 0.80 molar times or more, and more preferably 1.0 molar time or more.

[0094] The temperature in step (5) is not limited as long as the above reaction proceeds, but for example, 150°C or lower is preferred, 120°C or lower is more preferred, and 90°C or lower is even more preferred. Also, -20°C or higher is preferred, 0°C or higher is more preferred, and 20°C or higher is even more preferred. At the above temperatures, side reactions are less likely to occur, and the reaction can proceed efficiently.

[0095] The reaction in step (5) can be carried out in a solvent. A solvent in which compound (f) and a sodium source are dissolved is preferred. For example, the solubility of compound (f) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more.

[0096] Specifically, the solvent is preferably water or alcohols, and may also be a mixed solvent of water and alcohols. The alcohols are not particularly limited, but methanol, ethanol, isopropyl alcohol, etc., can be used.

[0097] Step (5) may involve, for example, adding a solution of a sodium source dissolved in a solvent to compound (f) and stirring, or adding compound (f) to a sodium source dissolved in a solvent. Compound (f) may be used as is, or it may be dissolved in any solvent. In this case, the stirring time is not particularly limited, but for example, it is 0.1 to 24 hours.

[0098] The third manufacturing method may include a step of recovering compound (1) obtained in step (5), and may further include a purification step such as pH adjustment or recrystallization.

[0099] Of the compounds (1), R 101 and R 102 Compound (11) in which at least one of is -F, or compound (1) in which R 101 and R 102 (The above R 101 and R 102 Compound (12) in which all of the substituents H are replaced with F is, for example, the following general formula (g): [ka] (In the formula, R 211 and R 212 Each is independent of the others. -H, Formula:-O p101 -(SiR 103 20) n101 -SiR 104 3(R 103 and R 104 These are groups represented by ), where one or more hydrogens may be substituted with fluorine, an alkyl group, an alkenyl group, an alkynyl group, or an aryl group, where one or more hydrogens may be substituted with fluorine, n101 is an integer of 0 or more, and p101 is 0 or 1. Alkyl alkyl groups with 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups with 6 to 15 carbon atoms, -SO2X 101 (X 101 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, -SO3X 102 (X 102 is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, The substituents described above may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO2X 103 (X 103 (is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, R 211 and R 212 At least one of the two has one or more hydrogen atoms. The compound (g) represented by ( ) can be suitably produced by a production method (hereinafter also referred to as the fourth production method) which includes step (6) of reacting a sodium source and a mixed gas containing fluorine with the compound (g) represented by ( ) to obtain compound (11) or compound (12).

[0100] R in general formula (g) 211 and R 212 As above -O p101 -(SiR 103 20) n101 -SiR 104 3. The alkyl group, the alkenyl group, the alkynyl group, the aryl group, the -SO2X 101 and the above-SO3X 102 For example, R in general formula (1) 101 and R 102 Similar examples include the above. However, R 211 and R 212 At least one of them must have one or more hydrogen atoms.

[0101] Step (6) described above can be carried out, for example, by introducing a solvent into a reaction vessel, adding the compound (g) and a sodium source to the introduced solvent, and bubbling a mixed gas containing fluorine of any concentration therein. The amount of water is not particularly limited, but it is preferable to use 1.0 to 100 times the amount of compound (g) by mass ratio.

[0102] In step (6) described above, it is preferable to carry out the procedure at a temperature of 0 to 5°C in order to suppress side reactions.

[0103] The sodium source in step (6) is preferably sodium hydroxide, sodium hydride, or metallic sodium, with sodium hydroxide being more preferred.

[0104] The fluorine-containing mixed gas in step (6) can be used as a mixed gas obtained by mixing fluorine and an inert gas at any concentration. The concentration of fluorine gas is preferably 1.0 to 20% by volume in the mixed gas, as this allows for easy control of the reaction and efficient reaction progress.

[0105] As the inert gas mentioned above, noble gases such as argon or nitrogen gas can be used, and nitrogen gas is preferred.

[0106] The amount of sodium source used in step (6) is preferably 1.5 molar times or less, more preferably 1.2 molar times or less, and even more preferably 1.1 molar times or less, relative to the compound (g). The lower limit is not particularly limited, but is usually 0.50 molar times or more, preferably 0.80 molar times or more, and more preferably 1.0 molar time or more.

[0107] The reaction in step (6) can be carried out in a solvent. A solvent in which the compound (g) and the sodium source are dissolved is preferred. For example, the solubility of the compound (g) at room temperature is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more.

[0108] Specifically, the solvent is preferably water or alcohols, and more preferably water.

[0109] The reaction time in step (6) is not particularly limited as long as it is sufficient time for compound (g) to be sufficiently fluorinated, but is preferably 0.1 to 72 hours, more preferably 0.1 to 24 hours, and even more preferably 0.5 to 12 hours.

[0110] The fourth manufacturing method may include a step of recovering compound (11) or compound (12) obtained in step (6), and may further include a purification step such as pH adjustment or recrystallization.

[0111] Compound (1) may be used alone or in combination of two or more types.

[0112] The electrolyte of this disclosure preferably contains 0.0001 to 10% by mass of compound (1) relative to the electrolyte. When the content of compound (1) is within the above range, the Coulomb efficiency can be further improved. The content of compound (1) is more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, even more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and particularly preferably 0.2% by mass or more. Furthermore, it is more preferably 5% by mass or less, even more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1.6% by mass or less, even more preferably 1.2% by mass or less, particularly preferably 1.0% by mass or less, and most preferably 0.8% by mass or less.

[0113] The electrolyte of this disclosure preferably contains a solvent.

[0114] The above solvent preferably contains at least one selected from the group consisting of carbonates and carboxylic acid esters.

[0115] The above-mentioned carbonate may be a cyclic carbonate or a chain carbonate.

[0116] The above-mentioned cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0117] Examples of the above-mentioned non-fluorinated cyclic carbonates include non-fluorinated saturated cyclic carbonates, with non-fluorinated saturated alkylene carbonates having alkylene groups with 2 to 6 carbon atoms being preferred, and non-fluorinated saturated alkylene carbonates having alkylene groups with 2 to 4 carbon atoms being more preferred.

[0118] In particular, as the non-fluorinated saturated cyclic carbonate, at least one selected from the group consisting of ethylene carbonate, propylene carbonate, cis-2,3-pentylene carbonate, cis-2,3-butylene carbonate, 2,3-pentylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,2-butylene carbonate, and butylene carbonate is preferred because it has a high dielectric constant and suitable viscosity.

[0119] The above-mentioned non-fluorinated saturated cyclic carbonates may be used individually or in combination of two or more in any combination and ratio.

[0120] If the above-mentioned non-fluorinated saturated cyclic carbonate is included, the content of the above-mentioned non-fluorinated saturated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume relative to the above-mentioned solvent.

[0121] The above-mentioned fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. Solvents containing fluorinated cyclic carbonates can be suitably used even under high voltage. In this specification, "high voltage" refers to a voltage of 4.2V or higher. The upper limit of "high voltage" is preferably 5.5V, and more preferably 5.0V.

[0122] The above-mentioned fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0123] The above-mentioned fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, and specifically, the following general formula (A):

[0124] [ka] (In the formula, X 1 ~X 4 The same or different, each representing -H, -CH3, -C2H5, -F, a fluorinated alkyl group which may have an ether linkage, or a fluorinated alkoxy group which may have an ether linkage. However, X 1 ~X 4 At least one of the members is -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond. Examples of compounds represented by ) are the above fluorinated alkyl groups such as -CF3, -CF2H, and -CH2F.

[0125] When the electrolyte of this disclosure is applied to a high-voltage sodium-ion secondary battery or the like, the oxidation resistance of the electrolyte is improved, and stable and excellent charge-discharge characteristics are obtained. In this specification, "ether bond" refers to a bond represented by -O-.

[0126] Due to its good dielectric constant and oxidation resistance, X 1 ~X 4 Preferably, one or two of these are -F, a fluorinated alkyl group which may have an ether linkage, or a fluorinated alkoxy group which may have an ether linkage.

[0127] Because it is expected to reduce viscosity at low temperatures, increase the flash point, and further improve the solubility of the electrolyte salt, X 1 ~X 4 Preferably, the element is -H, -F, a fluorinated alkyl group (a), a fluorinated alkyl group having an ether linkage (b), or a fluorinated alkoxy group (c).

[0128] The above-mentioned fluorinated alkyl group (a) is obtained by substituting at least one hydrogen atom of the alkyl group with a fluorine atom. The number of carbon atoms in the fluorinated alkyl group (a) is preferably 1 to 20, more preferably 1 to 17, even more preferably 1 to 7, and particularly preferably 1 to 5. If the number of carbon atoms becomes too large, the low-temperature properties may deteriorate and the solubility of the electrolyte salt may decrease. Conversely, if the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and an increase in viscosity may occur.

[0129] Among the above-mentioned fluorinated alkyl groups (a), those having one carbon atom include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- are preferred in terms of high-temperature storage characteristics, and CF3- is the most preferred.

[0130] Of the above fluorinated alkyl groups (a), those with 2 or more carbon atoms are defined by the following general formula (a-1): R a1 -R a2 - (a-1) (In the formula, R a1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom; a2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom; however, R a1 and R a2 A fluorinated alkyl group represented by (at least one of which has a fluorine atom) can be preferably exemplified from the viewpoint of good solubility of the electrolyte salt. Note, R a1 and R a2 It may further contain atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0131] R a1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom. a1 As such, linear or branched alkyl groups having 1 to 16 carbon atoms are preferred. a1 The number of carbon atoms is more preferably 1 to 6, and even more preferably 1 to 3.

[0132] Ra1 Specifically, as linear or branched alkyl groups, CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0133] [ka]

[0134] These are some examples.

[0135] Also, R a1If the alkyl group is a linear alkyl group with a fluorine atom, then the names are CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH 2CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2C H2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2 CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2 Examples include CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc.

[0136] Also, R a1 If it is a branched alkyl group having a fluorine atom,

[0137] [ka]

[0138] [ka]

[0139] These are some examples of preferred structures. However, since the presence of CH3- or CF3- branches tends to increase viscosity, it is more preferable that the number of such branches be small (1) or zero.

[0140] R a2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom. a2 The alkylene group may be linear or branched. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below. a2 These are composed of one or a combination of these.

[0141] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0142] (ii) The smallest structural unit of a branched chain:

[0143] [ka]

[0144] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0145] R a2 When the structure is linear, it consists only of the minimum linear structural units described above, with -CH2-, -CH2CH2-, or -CF2- being preferred. -CH2- or -CH2CH2- is more preferred because it can further improve the solubility of the electrolyte salt.

[0146] R a2If it is branched, it consists of at least one of the branched minimum structural units described above, and the general formula is -(CX a X b )-(X a is H, F, CH3 or CF3;X b is CH3 or CF3. However, X b If it is CF3, X a Examples of materials that can be represented as (where is H or CH3) are preferred. These can particularly further improve the solubility of the electrolyte salt.

[0147] Preferred fluorinated alkyl(a) include, for example, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CHF-, CH3CF2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0148] [ka]

[0149] [ka]

[0150] These are some examples.

[0151] The above-mentioned fluorinated alkyl group (b) having an ether linkage is obtained by substituting at least one hydrogen atom of the alkyl group having an ether linkage with a fluorine atom. The above-mentioned fluorinated alkyl group (b) having an ether linkage preferably has 2 to 17 carbon atoms. If the number of carbon atoms is too high, the viscosity of the above-mentioned fluorinated saturated cyclic carbonate will increase, and the number of fluorine-containing groups will increase, which may lead to a decrease in the solubility of the electrolyte salt due to a decrease in dielectric constant and a decrease in compatibility with other solvents. From this viewpoint, the number of carbon atoms of the above-mentioned fluorinated alkyl group (b) having an ether linkage is more preferably 2 to 10, and even more preferably 2 to 7.

[0152] The alkylene group constituting the ether portion of the fluorinated alkyl group (b) having the above ether linkage may be a linear or branched alkylene group. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below.

[0153] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0154] (ii) The smallest structural unit of a branched chain:

[0155] [ka]

[0156] Alkylene groups may consist of these minimum structural units alone, or they may be composed of linear (i) units together, branched (ii) units together, or combinations of linear (i) and branched (ii) units. Preferred specific examples will be described later.

[0157] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0158] A more preferred fluorinated alkyl group having an ether bond is the general formula (b-1): R 3 -(OR 4 ) n1 - (b-1) (In the formula, R 3 R may have a fluorine atom, preferably an alkyl group having 1 to 6 carbon atoms; 4 n1 is an integer from 1 to 3, where R is an alkylene group having 1 to 4 carbon atoms, which may have a fluorine atom; n1 is an integer from 1 to 3; however, 3 and R 4 Examples include those represented by (at least one of which has a fluorine atom).

[0159] R 3 and R4 Examples include the following, and these can be appropriately combined to form a fluorinated alkyl group (b) having an ether bond represented by the above general formula (b-1), but are not limited to these.

[0160] (1)R 3 For example, the general formula is: X c 3C-(R 5 ) n2 -(3 X c The same or different, both are H or F;R 5 (1) is an alkylene group which may have 1 to 5 carbon atoms and a fluorine atom; n2 is preferably an alkyl group represented as 0 or 1.

[0161] If n2 is 0, R 3 Examples include CH3-, CF3-, HCF2-, and H2CF-.

[0162] A concrete example of the case where n2 is 1 is R 3The linearly chained elements are CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2-, CF3CH2CH2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH2CH2-, C F3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2CF 2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2CH 2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2C F2CF2CF2CH2CH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, CH3CF2-, CH3CH2-, CH3CF2CH2-, CH3CF2CF2-, CH3CH2CH2-, Examples include CH3CF2CH2CF2-, CH3CF2CF2CF2-, CH3CH2CF2CF2-, CH3CH2CH2CH2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CH2CF2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, etc.

[0163] n2 is 1 and R 3 However, as for branched chains,

[0164] [ka]

[0165] These are some examples.

[0166] However, if it has branches such as CH3- or CF3-, the viscosity tends to increase, 3 A linear structure is more preferable.

[0167] (2) -(OR 4 ) n1 -In this case, n1 is an integer between 1 and 3, preferably 1 or 2. Note that when n1 = 2 or 3, R 4 They can be the same or different.

[0168] R 4 Preferred specific examples include the following linear or branched chains.

[0169] Examples of linear molecules include -CH2-, -CHF-, -CF2-, -CH2CH2-, -CF2CH2-, -CF2CF2-, -CH2CF2-, -CH2CH2CH2-, -CH2CH2CF2-, -CH2CF2CH2-, -CH2CF2CF2-, -CF2CH2CH2-, -CF2CF2CH2-, -CF2CH2CF2-, -CF2CF2CF2-, etc.

[0170] As for branched chains,

[0171] [ka]

[0172] These are some examples.

[0173] The above-mentioned fluorinated alkoxy group (c) is obtained by substituting at least one hydrogen atom of the alkoxy group with a fluorine atom. The above-mentioned fluorinated alkoxy group (c) preferably has 1 to 17 carbon atoms. More preferably, it has 1 to 6 carbon atoms.

[0174] The above fluorinated alkoxy group (c) is represented by the general formula: X d 3C-(R 6 ) n3-O-(3 X d The same or different, both are H or F;R 6 preferably an alkylene group having 1 to 5 carbon atoms and possibly a fluorine atom; n3 is 0 or 1; however, 3 X d A fluorinated alkoxy group represented by (one of which contains a fluorine atom) is particularly preferred.

[0175] A specific example of the above fluorinated alkoxy group (c) is R in the above general formula (a-1). a1 An example of this is a fluorinated alkoxy group in which an oxygen atom is bonded to the terminal of the alkyl group shown as an example.

[0176] In the above-mentioned fluorinated saturated cyclic carbonate, the fluorine content of the fluorinated alkyl group (a), the fluorinated alkyl group having an ether bond (b), and the fluorinated alkoxy group (c) is preferably 10% by mass or more. If the fluorine content is too low, the effect of reducing viscosity at low temperatures and raising the flash point may not be sufficiently obtained. From this viewpoint, the above-mentioned fluorine content is more preferably 12% by mass or more, and even more preferably 15% by mass or more. The upper limit is usually 76% by mass. The fluorine content of the fluorinated alkyl group (a), the fluorinated alkyl group having an ether bond (b), and the fluorinated alkoxy group (c) is calculated based on the structural formula of each group using the formula {(number of fluorine atoms × 19) / formula weight of each group} × 100 (%).

[0177] Furthermore, from the standpoint of good dielectric constant and oxidation resistance, the fluorine content of the entire fluorinated saturated cyclic carbonate is preferably 10% by mass or more, and more preferably 15% by mass or more. The upper limit is usually 76% by mass. The fluorine content of the above-mentioned fluorinated saturated cyclic carbonate was calculated based on the structural formula of the fluorinated saturated cyclic carbonate using the formula {(number of fluorine atoms × 19) / molecular weight of the fluorinated saturated cyclic carbonate} × 100 (%).

[0178] Examples of the above-mentioned fluorinated saturated cyclic carbonates include the following:

[0179] X 1 ~X 4 As a specific example of a fluorinated saturated cyclic carbonate in which at least one of the elements is -F,

[0180] [ka] These are some examples. These compounds have high dielectric strength and good solubility as electrolyte salts.

[0181] In addition,

[0182] [ka]

[0183] Other options can also be used.

[0184] X 1 ~X 4 A specific example of a fluorinated saturated cyclic carbonate in which at least one of the atoms is a fluorinated alkyl group (a) and the rest are all -H is:

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] These are some examples.

[0189] X 1 ~X 4A specific example of a fluorinated saturated cyclic carbonate in which at least one of the members is a fluorinated alkyl group (b) or a fluorinated alkoxy group (c) having an ether linkage, and the rest are all -H, is:

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [ka]

[0196] These are some examples.

[0197] In particular, the above-mentioned fluorinated saturated cyclic carbonate is preferably one of the following compounds.

[0198] [ka]

[0199] [ka]

[0200] Other examples of the above-mentioned fluorinated saturated cyclic carbonates include trans-4,5-difluoro-1,3-dioxolan-2-one, 5-(1,1-difluoroethyl)-4,4-difluoro-1,3-dioxolan-2-one, 4-methylene-1,3-dioxolan-2-one, 4-methyl-5-trifluoromethyl-1,3-dioxolan-2-one, 4-ethyl-5-fluoro-1,3-dioxolan-2-one, and 4-ethyl-5,5-difluoro-1,3- Examples include dioxolan-2-one, 4-ethyl-4,5-difluoro-1,3-dioxolan-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolan-2-one, 4,4-difluoro-5-methyl-1,3-dioxolan-2-one, 4-fluoro-5-methyl-1,3-dioxolan-2-one, 4-fluoro-5-trifluoromethyl-1,3-dioxolan-2-one, and 4,4-difluoro-1,3-dioxolan-2-one.

[0201] Among the above-mentioned fluorinated saturated cyclic carbonates, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethylethylene carbonate (3,3,3-trifluoropropylene carbonate), and 2,2,3,3,3-pentafluoropropylethylene carbonate are more preferred.

[0202] The above-mentioned fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom, and fluorinated ethylene carbonate derivatives substituted with substituents having an aromatic ring or a carbon-carbon double bond are preferred. Specifically, examples include 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate.

[0203] The above-mentioned fluorinated cyclic carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0204] If the above-mentioned fluorinated cyclic carbonate is included, the content of the above-mentioned fluorinated cyclic carbonate is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume relative to the above-mentioned solvent.

[0205] The above-mentioned chain-like carbonate may be a non-fluorinated chain-like carbonate or a fluorinated chain-like carbonate.

[0206] Examples of the above-mentioned non-fluorinated linear carbonates include hydrocarbon-based linear carbonates such as CH3OCOOCH3 (dimethyl carbonate: DMC), CH3CH2OCOOCH2CH3 (diethyl carbonate: DEC), CH3CH2OCOOCH3 (ethyl methyl carbonate: EMC), CH3OCOOCH2CH2CH3 (methyl propyl carbonate), methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, dipropyl carbonate, dibutyl carbonate, methyl isopropyl carbonate, methyl-2-phenylphenyl carbonate, phenyl-2-phenylphenyl carbonate, trans-2,3-pentylene carbonate, trans-2,3-butylene carbonate, and ethylphenyl carbonate. Among these, it is preferable that it be at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate.

[0207] The above-mentioned non-fluorinated linear carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0208] When the above-mentioned non-fluorinated linear carbonate is included, the content of the above-mentioned non-fluorinated linear carbonate is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the above-mentioned solvent.

[0209] The above-mentioned fluorinated chain carbonate is a chain carbonate having fluorine atoms. Solvents containing fluorinated chain carbonates can be suitably used even under high voltage.

[0210] The above fluorinated chain carbonate is a general formula (B): Rf 2 OCOOR 7 (B) (In the formula, Rf 2 R is a fluorinated alkyl group having 1 to 7 carbon atoms. 7This is an alkyl group which may contain fluorine atoms having 1 to 7 carbon atoms. Examples of compounds represented by ) are shown below.

[0211] Rf 2 R is a fluorinated alkyl group having 1 to 7 carbon atoms. 7 This is an alkyl group which may contain fluorine atoms having 1 to 7 carbon atoms. The above fluorinated alkyl group is one in which at least one of the hydrogen atoms of the alkyl group is replaced with a fluorine atom. 7 If the alkyl group contains a fluorine atom, it becomes a fluorinated alkyl group. Rf 2 and R 7 In terms of low viscosity, the carbon number is preferably 1 to 7, and more preferably 1 to 2. If the number of carbon atoms becomes too large, the low-temperature properties may deteriorate and the solubility of the electrolyte salt may decrease. Conversely, if the number of carbon atoms is too small, a decrease in the solubility of the electrolyte salt, a decrease in discharge efficiency, and an increase in viscosity may occur.

[0212] Examples of fluorinated alkyl groups having one carbon atom include CFH2-, CF2H-, and CF3-. In particular, CFH2- or CF3- are preferred in terms of high-temperature storage characteristics.

[0213] Examples of fluorinated alkyl groups with 2 or more carbon atoms include those with the following general formula (d-1): R d1 -R d2 - (d-1) (In the formula, R d1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom; d2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom; however, R d1 and R d2 A fluorinated alkyl group represented by (at least one of which has a fluorine atom) can be preferably exemplified from the viewpoint of good solubility of the electrolyte salt. Note, R d1 and R d2 It may further contain atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0214] R d1 R is an alkyl group having 1 or more carbon atoms, which may contain a fluorine atom. d1 As such, linear or branched alkyl groups having 1 to 6 carbon atoms are preferred. d1 The number of carbon atoms is more preferably 1 to 3.

[0215] R d1 Specifically, as linear or branched alkyl groups, CH3-, CF3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-,

[0216] [ka]

[0217] These are some examples.

[0218] Also, R d1If the alkyl group is a linear alkyl group with a fluorine atom, then the names are CF3-, CF3CH2-, CF3CF2-, CF3CH2CH2-, CF3CF2CH2-, CF3CF2CF2-, CF3CH2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CH2-, CF3CF2CF2CF2-, CF3CF2CH2CF2-, CF3CF2CH2CH2CH2-, CF3CF2CH2CH 2CH2-, CF3CH2CF2CH2CH2-, CF3CF2CF2CH2CH2-, CF3CF2CF2CF2CH2-, CF3CF2CH2CF2CH2-, CF3CF2CH2CH2CH2CH2-, CF3CF2C F2CF2CH2CH2-, CF3CF2CH2CF2CH2CH2-, HCF2-, HCF2CH2-, HCF2CF2-, HCF2CH2CH2-, HCF2CF2CH2-, HCF2CH2CF2-, HCF2CF2C H2CH2-, HCF2CH2CF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CH2CH2CH2-, HCF2CH2CF2CH2CH2-, HCF2CF2CF2CF2CH2-, HCF2CF2CF2 CF2CH2CH2-, FCH2-, FCH2CH2-, FCH2CF2-, FCH2CF2CH2-, FCH2CF2CF2-, CH3CF2CH2-, CH3CF2CF2-, CH3CF2CH2CF2-, CH3CF2 Examples include CF2CF2-, CH3CH2CF2CF2-, CH3CF2CH2CF2CH2-, CH3CF2CF2CF2CH2-, CH3CF2CF2CH2CH2-, CH3CH2CF2CF2CH2-, CH3CF2CH2CF2CH2CH2-, CH3CF2CH2CF2CH2CH2-, HCFClCF2CH2-, HCF2CFClCH2-, HCF2CFClCF2CFClCH2-, HCFClCF2CFClCF2CH2-, etc.

[0219] Also, R d1 If it is a branched alkyl group having a fluorine atom,

[0220] [ka]

[0221] [ka]

[0222] These are some examples of preferred structures. However, since the presence of CH3- or CF3- branches tends to increase viscosity, it is more preferable that the number of such branches be small (1) or zero.

[0223] R d2 R is an alkylene group having 1 to 3 carbon atoms, which may contain a fluorine atom. d2 The alkylene group may be linear or branched. An example of the smallest structural unit constituting such a linear or branched alkylene group is shown below. d2 These are composed of one or a combination of these.

[0224] (i) Linear minimal structural unit: -CH2-, -CHF-, -CF2-, -CHCl-, -CFCl-, -CCl2-

[0225] (ii) The smallest structural unit of a branched chain:

[0226] [ka]

[0227] Furthermore, among the examples above, it is preferable that the constituent units do not contain Cl, as this prevents the deHCl reaction by a base and is therefore more stable.

[0228] R d2 When the structure is linear, it consists only of the minimum linear structural units described above, with -CH2-, -CH2CH2-, or -CF2- being preferred. -CH2- or -CH2CH2- is more preferred because it can further improve the solubility of the electrolyte salt.

[0229] R d2If it is branched, it consists of at least one of the branched minimum structural units described above, and the general formula is -(CX a X b )-(X a is H, F, CH3 or CF3;X b is CH3 or CF3. However, X b If it is CF3, X a Examples of materials that can be represented as (where is H or CH3) are preferred. These can particularly further improve the solubility of the electrolyte salt.

[0230] Preferred fluorinated alkyl groups include, specifically, CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0231] [ka]

[0232] [ka]

[0233] These are some examples.

[0234] Among them, Rf 2 and R 7 The preferred fluorinated alkyl groups are CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, and CF2H-. CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, and CF2H- are more preferred due to their high flame retardancy, good rate characteristics, and excellent oxidation resistance.

[0235] R 7 If it is an alkyl group that does not contain a fluorine atom, it is an alkyl group with 1 to 7 carbon atoms. 7In terms of low viscosity, the carbon number is preferably 1 to 4, and more preferably 1 to 3.

[0236] Examples of alkyl groups that do not contain fluorine atoms include CH3-, CH3CH2-, (CH3)2CH-, and C3H7-. Among these, CH3- and CH3CH2- are preferred due to their low viscosity and good rate characteristics.

[0237] The above-mentioned fluorinated chain carbonate preferably has a fluorine content of 15 to 70% by mass. When the fluorine content is within the above range, compatibility with solvents and solubility of salts can be maintained. The above-mentioned fluorine content is more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 35% by mass or more, more preferably 60% by mass or less, and even more preferably 50% by mass or less. In this disclosure, the fluorine content is determined based on the structural formula of the above-mentioned fluorinated chain carbonate. {(Number of fluorine atoms × 19) / Molecular weight of fluorinated chain carbonate} × 100 (%) This value was calculated using the method described above.

[0238] The above-mentioned fluorinated chain carbonate is preferably one of the following compounds in terms of its low viscosity.

[0239] [ka]

[0240] As the fluorinated chain carbonate mentioned above, methyl 2,2,2-trifluoroethyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0241] The above-mentioned fluorinated chain carbonates may be used individually, or two or more may be used in any combination and ratio.

[0242] When the above-mentioned fluorinated chain carbonate is included, the content of the above-mentioned fluorinated chain carbonate is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the above-mentioned solvent.

[0243] The above-mentioned carboxylic acid ester may be a cyclic carboxylic acid ester or a linear carboxylic acid ester.

[0244] The above-mentioned cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0245] Examples of the above-mentioned non-fluorinated cyclic carboxylic acid esters include non-fluorinated saturated cyclic carboxylic acid esters, and non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group with 2 to 4 carbon atoms are preferred.

[0246] Specific examples of non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group with 2 to 4 carbon atoms include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-valerolactone, and α-methyl-γ-butyrolactone. Among these, γ-butyrolactone and δ-valerolactone are particularly preferred in terms of improving the degree of sodium ion dissociation and load characteristics.

[0247] The above-mentioned non-fluorinated saturated cyclic carboxylic acid esters may be used individually or in combination of two or more in any combination and ratio.

[0248] If the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is included, the content of the above-mentioned non-fluorinated saturated cyclic carboxylic acid ester is preferably 0 to 90% by volume relative to the above-mentioned solvent, more preferably 0.001 to 90% by volume, even more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume.

[0249] The above-mentioned linear carboxylic acid ester may be a non-fluorinated linear carboxylic acid ester or a fluorinated linear carboxylic acid ester. When the above-mentioned solvent contains the above-mentioned linear carboxylic acid ester, the increase in resistance after high-temperature storage of the electrolyte can be further suppressed.

[0250] Examples of the above non-fluorinated linear carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, tert-butyl propionate, tert-butyl butyrate, sec-butyl propionate, sec-butyl butyrate, n-butyl butyrate, methyl pyrophosphate, ethyl pyrophosphate, tert-butyl formate, tert-butyl acetate, sec-butyl formate, sec-butyl acetate, n-hexyl pivalate, n-propyl formate, n-propyl Examples include propyl acetate, n-butyl formate, n-butyl pivalate, n-octyl pivalate, ethyl 2-(dimethoxyphosphoryl) acetate, ethyl 2-(dimethylphosphoryl) acetate, ethyl 2-(diethoxyphosphoryl) acetate, ethyl 2-(diethylphosphoryl) acetate, isopropyl propionate, isopropyl acetate, ethyl formate, ethyl 2-propynyl oxalate, isopropyl formate, isopropyl butyrate, isobutyl formate, isobutyl propionate, isobutyl butyrate, and isobutyl acetate.

[0251] Among these, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0252] The above-mentioned non-fluorinated linear carboxylic acid esters may be used individually or in combination of two or more in any combination and ratio.

[0253] If the above-mentioned non-fluorinated linear carboxylic acid ester is included, the content of the above-mentioned non-fluorinated linear carboxylic acid ester is preferably 0 to 90% by volume relative to the above-mentioned solvent, more preferably 0.001 to 90% by volume, even more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume.

[0254] The above-mentioned fluorinated linear carboxylic acid ester is a linear carboxylic acid ester having a fluorine atom. Solvents containing the fluorinated linear carboxylic acid ester can be suitably used even under high voltage.

[0255] The above fluorinated chain carboxylic acid esters are based on the following general formula: R 31 COOR 32 (In the formula, R 31 and R 32 These are alkyl groups that may contain fluorine atoms having 1 to 4 carbon atoms, and R 31 and R 32 At least one of them contains a fluorine atom. Fluorinated chain carboxylic acid esters represented by () are preferred because they have good compatibility with other solvents and oxidation resistance.

[0256] R 31 and R 32Examples include non-fluorinated alkyl groups such as methyl group (-CH3), ethyl group (-CH2CH3), propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), n-butyl group (-CH2CH2CH2CH3), and tert-butyl group (-C(CH3)3); -CF3, -CF2H, -CFH2, -CF2CF3, -CF2CF2H, -CF2CFH2, -CH2CF3, -CH2CF2H, -CH2CFH2, -CF2CF2CF3, -CF2CF2CF2H, -CF2CF2CFH2, -CH2CF2CF3, -CH2CF 2CF2H, -CH2CF2CFH2, -CH2CH2CF3, -CH2CH2CF2H, -CH2CH2CFH2, -CF(CF3)2, -CF(CF2H)2, -CF(CFH2)2, -CH(CF3)2, -CH(CF2H)2, -CH(CFH2)2, -CF(OCH) 3)CF3, -CF2CF2CF2CF3, -CF2CF2CF2CF2H, -CF2CF2CF2CFH2, -CH2CF2CF2CF3, -CH2CF2CF2CF2H, -CH2CF2CF2CFH2, -CH2CH2CF2CF3, -CH2CH2CF2CF2H, -C H2CH2CF2CFH2, -CH2CH2CH2CF3, -CH2CH2CH2CF2H, -CH2CH2CH2CFH2, -CF(CF3)CF2CF3, -CF(CF2H)CF2CF3, -CF(CFH2)CF2CF3, -CF(CF3)CF2CF2H, -CF( CF3)CF2CFH2, -CF(CF3)CH2CF3, -CF(CF3)CH2CF2H, -CF(CF3)CH2CFH2, -CH(CF3)CF2CF3, -CH(CF2H)CF2CF3, -CH(CFH2)CF2CF3, -CH(CF3)CF2CF2H, -CH (CF3)CF2CFH2, -CH(CF3)CH2CF3, -CH(CF3)CH2CF2H, -CH(CF3)CH2CFH2, -CF2CF(CF3)CF3, -CF2CF(CF2H)CF3, -CF2CF(CFH2)CF3, -CF2CF(CF3)CF2H, - CF2CF(CF3)CFH2, -CH2CF(CF3)CF3, -CH2CF(CF2H)CF3, -CH2CF(CFH2)CF3, -CH2CF(CF3)CF2H, -CH2CF(CF3)CFH2, -CH2CH(CF3)CF3, -CH2CH(CF2H)CF3,Examples include fluorinated alkyl groups such as -CH2CH(CFH2)CF3, -CH2CH(CF3)CF2H, -CH2CH(CF3)CFH2, -CF2CH(CF3)CF3, -CF2CH(CF2H)CF3, -CF2CH(CFH2)CF3, -CF2CH(CF3)CF2H, -CF2CH(CF3)CFH2, -C(CF3)3, -C(CF2H)3, and -C(CFH2)3. Among these, methyl groups, ethyl groups, -CF3, -CF2H, -CF2CF3, -CH2CF3, -CH2CF2H, -CH2CFH2, -CH2CH2CF3, -CH2CF2CF3, -CH2CF2CF3, -CH2CF2CF2H, and -CH2CF2CFH2 are particularly preferred due to their good compatibility with other solvents, viscosity, and oxidation resistance.

[0257] Specific examples of the above-mentioned fluorinated chain carboxylic acid esters include, for example, CF3CH2C(=O)OCH3 (methyl 3,3,3-trifluoropropionate), HCF2C(=O)OCH3 (methyl difluoroacetate), HCF2C(=O)OC2H5 (ethyl difluoroacetate), CF3C(=O)OCH2CH2CF3, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H (2,2,3,3-tetrafluoropropyl trifluoroacetate), CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tert-butyl trifluoroacetate, and n-butyl trifluoroacetate. Examples include one or more of the following: methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3 (2,2,2-trifluoroethyl acetate), 1H,1H-heptafluorobutyl acetate, methyl 4,4,4-trifluorobutyrate, 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropionate 3,3,3-trifluoropropyl, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, 2,2-difluorobutyl acetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate. Among them, CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, CF3C(=O)OCH2C2F5, CF3C(=O)OCH2CF2CF2H, CF3C(=O)OCH2CF3, CF3C(=O)OCH(CF3)2, ethyl pentafluorobutyrate, methyl pentafluoropropionate, ethyl pentafluoropropionate, methyl heptafluoroisobutyrate, isopropyl trifluorobutyrate, ethyl trifluoroacetate, tert-butyl trifluoroacetate, n-butyl trifluoroacetate, methyl tetrafluoro-2-(methoxy)propionate, 2,2-difluoroethyl acetate, 2,2,3,3-tetrafluoropropyl acetate, CH3C(=O)OCH2CF3, 1H,1H-heptafluorobutyl acetate, 4,4,4-methyl trifluorobutyrate, Ethyl 4,4,4-trifluorobutyrate, ethyl 3,3,3-trifluoropropionate, 3,3,3-trifluoropropyl 3,3,3-trifluoropropionate, ethyl 3-(trifluoromethyl)butyrate, methyl 2,3,3,3-tetrafluoropropionate, butyl 2,2-difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate are preferred due to their good compatibility with other solvents and rate characteristics, CF3CH2C(=O)OCH3, HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are more preferred, and HCF2C(=O)OCH3, HCF2C(=O)OC2H5, and CH3C(=O)OCH2CF3 are particularly preferred.

[0258] The above-mentioned fluorinated chain carboxylic acid esters may be used individually, or two or more may be used in any combination and ratio.

[0259] If the above-mentioned fluorinated linear carboxylic acid ester is included, the content of the above-mentioned fluorinated linear carboxylic acid ester is preferably 10 to 90% by volume, more preferably 40 to 85% by volume, and even more preferably 50 to 80% by volume relative to the above-mentioned solvent.

[0260] The solvent preferably contains at least one selected from the group consisting of the cyclic carbonate, the linear carbonate, and the linear carboxylic acid ester, and more preferably contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester. The cyclic carbonate is preferably a saturated cyclic carbonate. An electrolyte containing a solvent with the above composition can further improve the high-temperature storage characteristics and cycling characteristics of electrochemical devices.

[0261] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester, it is preferable that the total amount of the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester be 10 to 100% by volume, more preferably 30 to 100% by volume, and even more preferably 50 to 100% by volume.

[0262] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester, the volume ratio of the cyclic carbonate to at least one selected from the group consisting of the linear carbonate and the linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, even more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0263] The solvent may also preferably contain at least one selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated linear carbonate, and the non-fluorinated linear carboxylic acid ester, and more preferably contain the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester. An electrolyte containing a solvent of the above composition can be suitably used in electrochemical devices that operate at relatively low voltages.

[0264] When the above solvent contains the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated linear carbonate and the above non-fluorinated linear carboxylic acid ester, it is preferable that the total amount of the above non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the above non-fluorinated linear carbonate and the above non-fluorinated linear carboxylic acid ester be 5 to 100% by volume, more preferably 20 to 100% by volume, and even more preferably 30 to 100% by volume.

[0265] When the electrolyte contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester, the volume ratio of the non-fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the non-fluorinated linear carbonate and the non-fluorinated linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, even more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0266] The solvent may also preferably contain at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated linear carbonate, and the fluorinated linear carboxylic acid ester, and more preferably contain the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester. An electrolyte containing a solvent of the above composition can be suitably used not only in electrochemical devices used at relatively low voltages, but also in electrochemical devices used at relatively high voltages.

[0267] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester, it is preferable that the total amount of the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester be 5 to 100% by volume, more preferably 10 to 100% by volume, and even more preferably 30 to 100% by volume.

[0268] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester, the volume ratio of the fluorinated saturated cyclic carbonate to at least one selected from the group consisting of the fluorinated linear carbonate and the fluorinated linear carboxylic acid ester is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, particularly preferably 20 / 80 or more, more preferably 90 / 10 or less, even more preferably 60 / 40 or less, and particularly preferably 50 / 50 or less.

[0269] Furthermore, ionic liquids can also be used as the solvent. An "ionic liquid" is a liquid composed of ions, which are a combination of organic cations and anions.

[0270] The organic cation is not particularly limited, but examples include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0271] The anions that act as counters to these organic cations are not particularly limited, but examples include PF6 anion, PF3(C2F5)3 anion, PF3(CF3)3 anion, BF4 anion, BF2(CF3)2 anion, BF3(CF3) anion, bisoxalatoborate anion, P(C2O4)F2 anion, Tf(trifluoromethanesulfonyl) anion, Nf(nonafluorobutanesulfonyl) anion, bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, dicyanoamine anion, and halide anions.

[0272] The solvent is preferably a non-aqueous solvent, and the electrolyte of this disclosure is preferably a non-aqueous electrolyte. The solvent content is preferably 70 to 99.999% by mass in the electrolyte, more preferably 80% by mass or more, and even more preferably 92% by mass or less.

[0273] The electrolyte of this disclosure preferably further contains an electrolyte salt (except for compound (1)). As the electrolyte salt, any salt that can be used in an electrolyte can be used, such as sodium salts, ammonium salts, metal salts, liquid salts (ionic liquids), inorganic polymer type salts, organic polymer type salts, etc.

[0274] For electrolyte solutions in sodium-ion secondary batteries, sodium salts are preferred as the electrolyte salt. Any sodium salt can be used as described above, and specifically, the following are examples: NaPF6, NaBF4, NaClO4, NaAlF4, NaSbF6, NaTaF6, NaWF7, NaAsF6, NaAlCl4, NaI, NaBr, NaCl, NaB 10 Cl 10 Inorganic sodium salts such as Na2SiF6, Na2PFO3, and NaPO2F2; Tungsten sodium acids such as NaWOF5; Sodium carboxylate salts such as HCO2Na, CH3CO2Na, CH2FCO2Na, CHF2CO2Na, CF3CO2Na, CF3CH2CO2Na, CF3CF2CO2Na, CF3CF2CF2CO2Na, CF3CF2CF2CF2CO2Na, etc. Sodium salts containing an S=O group, such as FSO3Na, CH3SO3Na, CH2FSO3Na, CHF2SO3Na, CF3SO3Na, CF3CF2SO3Na, CF3CF2CF2SO3Na, CF3CF2CF2CF2SO3Na, sodium methyl sulfate, sodium ethyl sulfate (C2H5OSO3Na), and sodium 2,2,2-trifluoroethyl sulfate; Sodium imide salts such as NaN(FCO)2, NaN(FCO)(FSO2), NaN(FSO2)2, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, sodium bisperfluoroethanesulfonylimide, sodium cyclic 1,2-perfluoroethanedisulfonylimide, sodium cyclic 1,3-perfluoropropanedisulfonylimide, sodium cyclic 1,2-ethanedisulfonylimide, sodium cyclic 1,3-propanedisulfonylimide, sodium cyclic 1,4-perfluorobutanedisulfonylimide, NaN(CF3SO2)(FSO2), NaN(CF3SO2)(C3F7SO2), NaN(CF3SO2)(C4F9SO2), NaN(POF2)2, etc. Sodium methide salts such as NaC(FSO2)3, NaC(CF3SO2)3, and NaC(C2F5SO2)3; Other formulas: NaPF a (C n F 2n+1 ) 6-aSalts represented by (wherein the formula a is an integer from 0 to 5 and n is an integer from 1 to 6) (e.g., NaPF3(C2F5)3, NaPF3(CF3)3, NaPF3(iso-C3F7)3, NaPF5(iso-C3F7), NaPF4(CF3)2, NaPF4(C2F5)2), NaPF4(CF3SO2)2, NaPF4(C2F5SO2)2, NaBF3CF3, NaBF3C2F5, NaBF3C3F7, NaBF2(CF3)2, NaBF2(C2F5)2, NaBF2(CF3SO2)2, NaBF2(C2F5SO2)2, etc., including fluorine-containing organic sodium salts, NaSCN, NaB(CN)4, NaB(C6H5)4, Na2(C2O4), NaP(C2O4)3, Na2B 12 F b H 12-b Examples include (where b is an integer between 0 and 3).

[0275] Among these, NaPF6, NaBF4, NaSbF6, NaTaF6, NaPO2F2, FSO3Na, CF3SO3Na, NaN(FSO2)2, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, sodium cyclic 1,2-perfluoroethanedisulfonylimide, sodium cyclic 1,3-perfluoropropanedisulfonylimide, NaC(FSO2)3, NaC(CF3SO2)3, NaC(C2F5SO2)3, NaBF3CF3, NaBF3C2F5, NaPF3(CF3)3, NaPF3(C2F5)3, etc. are particularly preferred because they have the effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, and cycle characteristics.

[0276] From the viewpoint of Coulomb efficiency and capacity retention rate, the sodium salt is preferably at least one selected from the group consisting of NaPF6, NaBF4, NaN(FSO2)2, and NaN(CF3SO2)2, more preferably at least one selected from the group consisting of NaPF6 and NaN(FSO2)2, and even more preferably NaN(FSO2)2 (sodium bis(fluorosulfonyl)imide, NaFSI).

[0277] The concentrations of these electrolyte salts in the electrolyte are not particularly limited. In order to maintain a good electrical conductivity of the electrolyte and ensure good battery performance, the total molar concentration of sodium in the electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, even more preferably 0.5 mol / L or more, and also preferably 3.5 mol / L or less, more preferably 2.5 mol / L or less, even more preferably 1.5 mol / L or less, and even more preferably 1.0 mol / L or less.

[0278] If the total molar concentration of sodium is too low, the electrical conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to increased viscosity, which may reduce battery performance.

[0279] The electrolyte of this disclosure is general formula (2): [ka] (In the formula, X 21 is a base containing at least H or C, n21 is an integer from 1 to 3, Y 21 and Z 21 The group is the same or different and contains at least H, C, O or F, n22 is 0 or 1, Y 21 and Z 21 The compounds may bond to each other to form a ring. Preferably, the electrolyte further contains compound (2) represented by ). When the electrolyte contains compound (2), the volume retention rate is less likely to decrease and the amount of gas generated is less likely to increase, even when stored at high temperatures.

[0280] If n21 is 2 or 3, then 2 or 3 X 21 They may be the same or different. Y 21 and Z 21 If there are multiple instances of Y, then there are multiple instances of Y. 21 and Z 21 They may be the same or different.

[0281] X 21 For example, -CY 21 Z 21-(In the formula, Y 21 and Z 21 (As stated above) or -CY 21 =CZ 21 -(In the formula, Y 21 and Z 21 The group shown above is preferred.

[0282] Y 21 Preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is used. Z 21 Preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is used.

[0283] Or, Y 21 and Z 21 These atoms can bond with each other to form a carbocyclic or heterocyclic ring, which may contain unsaturated bonds and may be aromatic. The number of carbon atoms in the ring is preferably 3 to 20.

[0284] Next, specific examples of compound (2) will be described. In the following examples, "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure, to the extent that it does not contradict the spirit of this disclosure. Examples include dimers, trimers, and tetramers consisting of multiple acid anhydrides, or isostructural isomers having branched chains but the same number of carbon atoms in the substituents, or those in which the substituents are attached to the acid anhydride at different sites.

[0285] Specific examples of acid anhydrides that form a five-membered ring structure include succinic anhydride, methylsuccinate anhydride (4-methylsuccinate anhydride), dimethylsuccinate anhydride (4,4-dimethylsuccinate anhydride, 4,5-dimethylsuccinate anhydride, etc.), 4,4,5-trimethylsuccinate anhydride, 4,4,5,5-tetramethylsuccinate anhydride, 4-vinylsuccinate anhydride, 4,5-divinylsuccinate anhydride, phenylsuccinate anhydride (4-phenylsuccinate anhydride), and 4,5-diphenylsuccinate anhydride. Examples include aqueous solutions, 4,4-diphenylsuccinic anhydride, citraconic anhydride, maleic anhydride, methylmaleic anhydride (4-methylmaleic anhydride), 4,5-dimethylmaleic anhydride, phenylmaleic anhydride (4-phenylmaleic anhydride), 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, and their analogues.

[0286] Specific examples of acid anhydrides forming a six-membered ring structure include cyclohexanedicarboxylic acid anhydride (such as cyclohexane-1,2-dicarboxylic acid anhydride), 4-cyclohexene-1,2-dicarboxylic acid anhydride, glutaric acid anhydride, glutaconic acid anhydride, 2-phenylglutaric acid anhydride, and their analogues.

[0287] Other specific examples of acid anhydrides that form a cyclic structure include 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic anhydride, diglycolic acid anhydride, and their analogues.

[0288] Specific examples of acid anhydrides that form a cyclic structure and are substituted with halogen atoms include monofluorosuccinic anhydride (such as 4-fluorosuccinic anhydride), 4,4-difluorosuccinic anhydride, 4,5-difluorosuccinic anhydride, 4,4,5-trifluorosuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride (4,4,5,5-tetrafluorosuccinic anhydride), 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, trifluoromethylmaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and their analogues.

[0289] Among the compounds (2), glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylsuccinic anhydride, 2-phenylglutaric anhydride, maleic anhydride, methylmaleic anhydride, trifluoromethyl Maleic anhydride, phenylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, tetrafluorosuccinic anhydride, etc. are preferred, maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride, tetrafluorosuccinic anhydride are more preferred, and maleic anhydride and succinic anhydride are even more preferred.

[0290] Compound (2) has the general formula (3):

[0291] [ka] (In the formula, X 31 ~X 34(3) is a compound represented by the same or different group (containing at least H, C, O, or F), and the general formula (4):

[0292] [ka] (In the formula, X 41 and X 42 Preferably, is at least one selected from the group consisting of compounds (4) that are the same or different and represent a group containing at least H, C, O, or F.

[0293] X 31 ~X 34 Preferably, it is the same or different, and selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups. 31 ~X 34 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0294] X 31 ~X 34 More preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is the same or different.

[0295] X 41 and X 42 Preferably, it is the same or different, and selected from the group consisting of alkyl groups, fluorinated alkyl groups, alkenyl groups, and fluorinated alkenyl groups. 41 and X 42 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0296] X 41 and X 42More preferably, at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2- is the same or different.

[0297] Compound (3) is preferably one of the following compounds.

[0298] [ka]

[0299] Compound (4) is preferably one of the following compounds.

[0300] [ka]

[0301] The above electrolyte is preferably contained in an amount of compound (2) of 0.0001 to 15% by mass, since its volume retention rate does not decrease easily and the amount of gas generated does not increase easily even when stored at high temperatures. The compound (2) content is more preferably 0.01 to 10% by mass, even more preferably 0.1 to 3% by mass, and particularly preferably 0.1 to 1.0% by mass.

[0302] When the electrolyte contains both compounds (3) and (4), the volume retention rate does not decrease easily and the amount of gas generated does not increase easily even when stored at high temperatures. Therefore, the electrolyte preferably contains 0.08 to 2.50% by mass of compound (3) and 0.02 to 1.50% by mass of compound (4) relative to the electrolyte, and more preferably contains 0.80 to 2.50% by mass of compound (3) and 0.08 to 1.50% by mass of compound (4).

[0303] The electrolyte of this disclosure may contain at least one selected from the group consisting of nitrile compounds represented by the following general formulas (1a), (1b), and (1c). [ka] (In the formula, R a and R b Each of these independently represents a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms are replaced with halogen atoms. n represents an integer from 1 to 10. [ka] (In the formula, R c This includes hydrogen atoms, halogen atoms, alkyl groups, groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 X is an alkylene group. c1 represents an oxygen atom or a sulfur atom. ) represents a group represented by ). d and R e Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. (m represents an integer from 1 to 10.) [ka] (In the formula, R f , R g , R h and R i Each of these independently represents a group containing a cyano group (CN), a hydrogen atom (H), a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms are replaced with halogen atoms. However, R f , R g , R h and R i At least one of these groups contains a cyano group. (l represents an integer from 1 to 3.) This improves the high-temperature storage characteristics of electrochemical devices. The above nitrile compounds may be used alone, or two or more may be used in any combination and ratio.

[0304] In the above general formula (1a), R a and R b Each of these is independently a hydrogen atom, a cyano group (CN), a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Among these, fluorine is preferred. Alkyl groups with 1 to 5 carbon atoms are preferred. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl groups. Examples of groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms include the aforementioned groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. R a and R b If is an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, then R a and R b These elements may be bonded to each other to form a ring structure (for example, a cyclohexane ring). R a and R b It is preferable that this is a hydrogen atom or an alkyl group.

[0305] In the general formula (1a) above, n is an integer from 1 to 10. If n is 2 or greater, there are n R a They may all be the same, or at least some of them may be different. b The same applies to n. n is preferably an integer between 1 and 7, and more preferably an integer between 2 and 5.

[0306] Dinitrile and tricarbonitrile are preferred as nitrile compounds represented by the above general formula (1a). Specific examples of dinitriles include malononitrile, succinonitrile, glutalonitrile, adiponitrile, pimelonitrile, suberonitrile, azeranitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2 ,3,3-trimethylsuccinonitrile, 2,2,3,3-tetramethylsuccinonitrile, 2,3-diethyl-2,3-dimethylsuccinonitrile, 2,2-diethyl-3,3-dimethylsuccinonitrile, bicyclohexyl-1,1-dicarbonitrile, bicyclohexyl-2,2-dicarbonitrile, bicyclohexyl-3,3-dicarbonitrile, 2,5-dimethyl-2,5-hexanedicarbonitrile, 2,3-diisobutyl-2,3- Dimethyl succinonitrile, 2,2-diisobutyl-3,3-dimethyl succinonitrile, 2-methyl glutaronitrile, 2,3-dimethyl glutaronitrile, 2,4-dimethyl glutaronitrile, 2,2,3,3-tetramethyl glutaronitrile, 2,2,4,4-tetramethyl glutaronitrile, 2,2,3,4-tetramethyl glutaronitrile, 2,3,3,4-tetramethyl glutaronitrile, 1,4-dicyanopentane, 2,6-disy Examples include anoheptane, 2,7-dicyanooctane, 2,8-dicyanononane, 1,6-dicyanodecane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, 3,3'-(ethylenedioxy)dipropionitrile, 3,3'-(ethylenedithio)dipropionitrile, 3,9-bis(2-cyanoethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, butanenitrile, phthalonitrile, etc. Of these, succinonitrile, glutalonitrile, and adiponitrile are particularly preferred. Furthermore, specific examples of tricarbonitrine include pentanetricarbonitrine, propanetricarbonitrine, 1,3,5-hexanetricarbonitrine, 1,3,6-hexanetricarbonitrine, heptanetricarbonitrine, 1,2,3-propanetricarbonitrine, 1,3,5-pentanetricarbonitrine, cyclohexanetricarbonitrine, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, tris(2-cyanoethyl)amine, etc., with 1,3,6-hexanetricarbonitrine and cyclohexanetricarbonitrine being particularly preferred, and cyclohexanetricarbonitrine being the most preferred.

[0307] In the above general formula (1b), R c This includes hydrogen atoms, halogen atoms, alkyl groups, groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 X is an alkylene group. c1 represents an oxygen atom or a sulfur atom. ) is a group represented by R d and R e Each of these is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms, alkyl groups, and groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms are those shown for the general formula (1a) above. The above NC-R c1 -X c1 -R in c1 This is an alkylene group. A preferred alkylene group has 1 to 3 carbon atoms. R c , R d and R e Preferably, each of these is independently a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. R c , R d and R ePreferably, at least one of the groups is a halogen atom or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a halogen atom, and more preferably, a fluorine atom or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with a fluorine atom. R d and R e If is an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms, then R d and R e These elements may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0308] In the general formula (1b) above, m is an integer from 1 to 10. If m is 2 or greater, there are m R d They may all be the same, or at least some of them may be different. e The same applies to m. m is preferably an integer between 2 and 7, and more preferably an integer between 2 and 5.

[0309] Examples of nitrile compounds represented by the above general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, pentafluoropropionitrile, methoxyacetonitrile, benzonitrile, and the like. Of these, 3,3,3-trifluoropropionitrile is particularly preferred.

[0310] In the above general formula (1c), Rf , R g , R h and R i Each of these is independently a group containing a cyano group (CN), a hydrogen atom, a halogen atom, an alkyl group, or a group in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms. Examples of halogen atoms, alkyl groups, and groups in which at least some of the hydrogen atoms of an alkyl group are substituted with halogen atoms are those shown for the general formula (1a) above. Groups containing a cyano group include not only cyano groups but also groups in which at least some of the hydrogen atoms of an alkyl group are replaced with cyano groups. Examples of alkyl groups in this case are those exemplified for general formula (1a) above. R f , R g , R h and R i At least one of these groups is a cyano group. Preferably, R f , R g , R h and R i At least two of these groups contain a cyano group, and more preferably, R h and R i The group must contain a cyano group. h and R i If R is a group containing a cyano group, f and R g It is preferable that it be a hydrogen atom.

[0311] In the general formula (1c) above, l is an integer from 1 to 3. If l is 2 or greater, there are l R f They may all be the same, or at least some of them may be different. g The same applies to . l is preferably an integer between 1 and 2.

[0312] Examples of nitrile compounds represented by the above general formula (1c) include 3-hexendinitrile, mucononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentennitrile, 2-methyl-2-pentennitrile, 3-methyl-2-pentennitrile, and 2-hexennitrile, with 3-hexendinitrile and mucononitrile being preferred, and 3-hexendinitrile being particularly preferred.

[0313] The content of the above nitrile compound is preferably 0.2 to 7% by mass relative to the electrolyte. This further improves the high-temperature storage characteristics and safety of the electrochemical device at high voltage. The lower limit of the total content of the above nitrile compound is more preferably 0.3% by mass, and even more preferably 0.5% by mass. The upper limit is more preferably 5% by mass, even more preferably 2% by mass, and particularly preferably 0.5% by mass.

[0314] The electrolyte of this disclosure may contain a compound having an isocyanate group (hereinafter sometimes abbreviated as "isocyanate"). The above isocyanate is not particularly limited, and any isocyanate can be used. Examples of isocyanates include monoisocyanates, diisocyanates, triisocyanates, and the like.

[0315] Specific examples of monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanathoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, isocyanatocyclohexane, methoxycarbonyl isocyanate, ethoxycarbonyl isocyanate, propoxycarbonyl isocyanate, butoxycarbonyl isocyanate, methoxysulfonyl isocyanate, ethoxysulfonyl isocyanate, propoxysulfonyl isocyanate, butoxysulfonyl isocyanate, fluorosulfonyl isocyanate, methyl isocyanate, butyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and ethyl isocyanate.

[0316] Specific examples of diisocyanates include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanathoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,3-diisocyanatopropene, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, and 1,4-diisocyanato-2,3-difluorobutane. 1,5-Diisocyanato-2-pentene, 1,5-Diisocyanato-2-methylpentane, 1,6-Diisocyanato-2-hexene, 1,6-Diisocyanato-3-hexene, 1,6-Diisocyanato-3-fluorohexane, 1,6-Diisocyanato-3,4-Difluorohexane, Toluene diisocyanate, Xylene diisocyanate, Tolylene diisocyanate, 1,2-Bis(isocyanatomethyl)cyclohexane, 1,3-Bis(isocyanatomethyl) (Cyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, dicyclohexylmethane-1,1'-diisocyanate, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate Examples include bicyclo[2.2.1]heptane-2,5-diirbis(methyl isocyanate), bicyclo[2.2.1]heptane-2,6-diirbis(methyl isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylenediisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, etc.

[0317] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylenediisocyanate, 1,3,5-triisocyanatemethylbenzene, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 4-(isocyanatomethyl)octamethylene=diisocyanate.

[0318] Among these, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohexa-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,4-trimethylhexamethylene diisocyanate, and 2,2,4-trimethylhexamethylene diisocyanate are preferred because they are readily available industrially, keep the manufacturing cost of the electrolyte low, and contribute to the formation of a stable film-like structure from a technical standpoint, making them more preferable to use.

[0319] The isocyanate content is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is preferably 0.001% by mass or more and 1.0% by mass or less relative to the electrolyte. If the isocyanate content is above this lower limit, a sufficient improvement in cycle characteristics can be brought about in non-aqueous electrolyte secondary batteries. If it is below this upper limit, an initial increase in resistance of non-aqueous electrolyte secondary batteries can be avoided. The isocyanate content is more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and more preferably 0.8% by mass or less, even more preferably 0.7% by mass or less, and particularly preferably 0.6% by mass or less.

[0320] The electrolyte of this disclosure may contain a cyclic sulfonic acid ester. The cyclic sulfonic acid ester is not particularly limited, and any cyclic sulfonic acid ester can be used. Examples of cyclic sulfonic acid esters include saturated cyclic sulfonic acid esters, unsaturated cyclic sulfonic acid esters, saturated cyclic disulfonic acid esters, and unsaturated cyclic disulfonic acid esters.

[0321] Specific examples of saturated cyclic sulfonic acid esters include 1,3-propanesultone, 1-fluoro-1,3-propanesultone, 2-fluoro-1,3-propanesultone, 3-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 2-methyl-1,3-propanesultone, 3-methyl-1,3-propanesultone, 1,3-butanesultone, 1,4-butanesultone, 1-fluoro-1,4-butanesultone, 2-fluoro-1,4-butanesultone, 3-fluoro-1,4-butanesultone, 4-fluoro-1,4-butanesultone, 1-methyl-1,4-butanesultone, 2-methyl-1,4-butanesultone, 3-methyl-1,4-butanesultone, 4-methyl-1,4-butanesultone, and 2,4-butanesultone.

[0322] Specific examples of unsaturated cyclic sulfonic acid esters include 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3-sultone, 2-fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, and 2-methyl-1-propene n-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4 -Sultone, 1-fluoro-2-butene-1,4-sultone, 2-fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1,3-propensultone, 1-fluoro-3-butene-1,4-sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1-butene-1,4-sultone, 2-methyl-1-butene Examples include n-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, and 4-methyl-3-butene-14-sultone.

[0323] Among these, 1,3-propanesultone, 1-fluoro-1,3-propanesultone, 2-fluoro-1,3-propanesultone, 3-fluoro-1,3-propanesultone, and 1-propene-1,3-sultone are more preferably used due to their availability and their ability to contribute to the formation of stable film-like structures. The content of the cyclic sulfonic acid ester is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is preferably 0.001% by mass or more and 3.0% by mass or less relative to the electrolyte.

[0324] If the cyclic sulfonic acid ester content is above this lower limit, a sufficient improvement in cycle characteristics can be achieved in non-aqueous electrolyte secondary batteries. If it is below this upper limit, an increase in the manufacturing cost of non-aqueous electrolyte secondary batteries can be avoided. The cyclic sulfonic acid ester content is more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, more preferably 2.5% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.8% by mass or less.

[0325] The electrolyte of this disclosure may further contain polyethylene oxide having a weight-average molecular weight of 2000 to 4000 and having -OH, -OCOOH, or -COOH at its terminus. By including such compounds, the stability of the electrode interface can be improved, thereby enhancing the properties of the electrochemical device. Examples of the polyethylene oxides mentioned above include polyethylene oxide monool, polyethylene oxide carboxylic acid, polyethylene oxide diol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, and the like. These may be used individually or in combination of two or more. In particular, a mixture of polyethylene oxide monool and polyethylene oxide diol, and a mixture of polyethylene carboxylic acid and polyethylene dicarboxylic acid are preferred, as they result in better characteristics of the electrochemical device.

[0326] If the weight-average molecular weight of the polyethylene oxide is too low, it may be more susceptible to oxidative decomposition. A weight-average molecular weight of 3000 to 4000 is more preferable. The above weight-average molecular weight can be measured by converting it to polystyrene equivalent using gel permeation chromatography (GPC).

[0327] The polyethylene oxide content mentioned above is 1 × 10⁻⁶ in the electrolyte. -6 ~1 × 10 -2 A concentration of mol / kg is preferable. If the polyethylene oxide content is too high, it may impair the properties of the electrochemical device. The polyethylene oxide content mentioned above is 5 × 10 -6 A concentration of mol / kg or higher is more preferable.

[0328] The electrolyte of this disclosure may further contain, as additives, fluorinated saturated cyclic carbonates, unsaturated cyclic carbonates, overcharge inhibitors, and other known auxiliary agents. This makes it possible to suppress the deterioration of the characteristics of the electrochemical device.

[0329] Examples of fluorinated saturated cyclic carbonates include compounds represented by the general formula (A) described above. Among these, fluoroethylene carbonate, difluoroethylene carbonate, monofluoromethylethylene carbonate, trifluoromethylethylene carbonate, and 2,2,3,3,3-pentafluoropropylethylene carbonate (4-(2,2,3,3,3-pentafluoropropyl)-[1,3]dioxolan-2-one) are preferred. Fluorinated saturated cyclic carbonates may be used individually or in combination of two or more in any combination and ratio.

[0330] The content of the above-mentioned fluorinated saturated cyclic carbonate is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.1 to 3% by mass, relative to the above-mentioned electrolyte.

[0331] Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with substituents having aromatic rings or carbon-carbon double or carbon-carbon triple bonds, phenyl carbonates, vinyl carbonates, allyl carbonates, and catechol carbonates.

[0332] Examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-divinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, ethynylethylene carbonate, propargylethylene carbonate, methyl vinylene carbonate, and dimethyl vinylene carbonate.

[0333] Specific examples of ethylene carbonates substituted with substituents having aromatic rings or carbon-carbon double or carbon-carbon triple bonds include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, and 4-allyl-5-ethynylethylene. Examples include nylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, and 4-methyl-5-allylethylene carbonate.

[0334] Among these, vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, vinyl ethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, and 4-vinyl-5-ethynylethylene carbonate are preferred as unsaturated cyclic carbonates. Furthermore, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are particularly preferred because they form an even more stable interfacial protective film, with vinylene carbonate being the most preferred.

[0335] The molecular weight of the unsaturated cyclic carbonate is not particularly limited and can be any as long as it does not significantly impair the effects of this disclosure. Preferably, the molecular weight is 50 or more and 250 or less. Within this range, it is easy to ensure the solubility of the unsaturated cyclic carbonate in the electrolyte, and the effects of this disclosure are easily realized. More preferably, the molecular weight of the unsaturated cyclic carbonate is 80 or more, and more preferably 150 or less.

[0336] The method for producing unsaturated cyclic carbonates is not particularly limited, and they can be produced by arbitrarily selecting known methods.

[0337] Unsaturated cyclic carbonates may be used individually or in combination of two or more types in any combination and ratio.

[0338] The content of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure. The content of the unsaturated cyclic carbonate is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more, per 100% by mass of the electrolyte. Furthermore, the content is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. Within the above range, electrochemical devices using the electrolyte are more likely to exhibit a sufficient improvement in cycle characteristics, and it is easier to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity maintenance rate.

[0339] As unsaturated cyclic carbonates, in addition to the non-fluorinated unsaturated cyclic carbonates mentioned above, fluorinated unsaturated cyclic carbonates can also be suitably used. Fluorinated unsaturated cyclic carbonates are cyclic carbonates having unsaturated bonds and fluorine atoms. The number of fluorine atoms in a fluorinated unsaturated cyclic carbonate is not particularly limited, as long as it is one or more. In particular, the number of fluorine atoms is usually six or less, preferably four or less, and one or two atoms is most preferred.

[0340] Examples of fluorinated unsaturated cyclic carbonates include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with substituents having aromatic rings or carbon-carbon double bonds.

[0341] Examples of fluorinated vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, and 4-fluoro-5-vinylvinylene carbonate.

[0342] Examples of fluorinated ethylene carbonate derivatives substituted with substituents having an aromatic ring or a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, and 4,5-difluoro-4- Examples include lylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, and 4,5-difluoro-4-phenylethylene carbonate.

[0343] Among them, fluorinated unsaturated cyclic carbonates include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-vinylvinylene carbonate, 4-allyl-5-fluorovinylene carbonate, 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, and 4,4-difluoro-4-vinylethylene carbonate. Carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, and 4,5-difluoro-4,5-diallylethylene carbonate are more preferably used because they form a stable interfacial protective film.

[0344] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and can be any as long as it does not significantly impair the effects of this disclosure. Preferably, the molecular weight is 50 or more and 500 or less. Within this range, it is easy to ensure the solubility of the fluorinated unsaturated cyclic carbonate in the electrolyte.

[0345] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and it can be produced by arbitrarily selecting any known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

[0346] Fluorinated unsaturated cyclic carbonates may be used individually or in any combination and ratio of two or more types. Furthermore, the content of fluorinated unsaturated cyclic carbonates is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure. Typically, the content of fluorinated unsaturated cyclic carbonates is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and also preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, in 100% by mass of the electrolyte. Within this range, electrochemical devices using the electrolyte are more likely to exhibit a sufficient improvement in cycle characteristics, and it is easier to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity maintenance rate.

[0347] The electrolyte of this disclosure may contain compounds having triple bonds. The type of compound is not particularly limited as long as it has one or more triple bonds in its molecule. Specific examples of compounds having a triple bond include the following compounds: Hydrocarbon compounds such as 1-pentine, 2-pentine, 1-hexine, 2-hexine, 3-hexine, 1-heptine, 2-heptine, 3-heptine, 1-octin, 2-octin, 3-octin, 4-octin, 1-nonine, 2-nonine, 3-nonine, 4-nonine, 1-dodecine, 2-dodecine, 3-dodecine, 4-dodecine, 5-dodecine, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butine, 4-phenyl-1-butine, 4-phenyl-1-butine, 1-phenyl-1-pentine, 5-phenyl-1-pentine, 1-phenyl-1-hexine, 6-phenyl-1-hexine, diphenylacetylene, 4-ethynyltoluene, and dicyclohexylacetylene;

[0348] 2-Propynylmethyl carbonate, 2-Propynylethyl carbonate, 2-Propynylpropyl carbonate, 2-Propynylbutyl carbonate, 2-Propynylphenyl carbonate, 2-Propynylcyclohexyl carbonate, Di-2-Propynyl carbonate, 1-Methyl-2-Propynylmethyl carbonate, 1,1-Dimethyl-2-Propynylmethyl carbonate, 2-Butynylmethyl carbonate, 3-Butynylmethyl carbonate, 2-Pentynylmethyl carbonate Monocarbonates such as nates, 3-pentinylmethyl carbonate, and 4-pentinylmethyl carbonate; dicarbonates such as 2-butyn-1,4-diol dimethyl dicarbonate, 2-butyn-1,4-diol diethyl dicarbonate, 2-butyn-1,4-diol dipropyl dicarbonate, 2-butyn-1,4-diol dibutyl dicarbonate, 2-butyn-1,4-diol diphenyl dicarbonate, and 2-butyn-1,4-diol dicyclohexyl dicarbonate;

[0349] 2-propynyl acetate, 2-propynyl propionate, 2-propynyl butyrate, 2-propynyl benzoate, 2-propynyl cyclohexylcarboxylic acid, 1,1-dimethyl-2-propynyl acetate, 1,1-dimethyl-2-propynyl propionate, 1,1-dimethyl-2-propynyl butyrate, 1,1-dimethyl-2-propynyl benzoate, 1,1-dimethyl-2-propynyl cyclohexylcarboxylic acid, 2-butynyl acetate, 3-butynyl acetate, 2-pentynyl acetate, 3-pentynyl acetate, 4-pentynyl acetate, methyl acrylate, Ethyl acrylate, propyl acrylate, vinyl acrylate, 2-propenyl acrylate, 2-butenyl acrylate, 3-butenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methacrylate, 2-propenyl methacrylate, 2-butenyl methacrylate, 3-butenyl methacrylate, methyl 2-propate, ethyl 2-propate, propyl 2-propate, vinyl 2-propate, 2-propenyl 2-propate, 2-butenyl 2-propate, 3-butenyl 2-propate, 2 - Methyl butate, ethyl butate, propyl butate, vinyl butate, 2-propenyl butate, 2-butenyl butate, 3-butenyl butate, methyl butate, ethyl butate, propyl butate, vinyl butate, 2-propenyl butate, 2-butenyl butate, 3-butenyl butate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate Monocarboxylic acid esters such as 3-butenyl pentinate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate, 3-butenyl pentinate, methyl pentinate, ethyl pentinate, propyl pentinate, vinyl pentinate, 2-propenyl pentinate, 2-butenyl pentinate, 3-butenyl pentinate, fumarate esters, methyl trimethylacetate, ethyl trimethylacetate;

[0350] Dicarboxylic acid esters such as 2-butyne-1,4-diol diacetate, 2-butyne-1,4-diol dipropionate, 2-butyne-1,4-diol dibutyrate, 2-butyne-1,4-diol dibenzoate, 2-butyne-1,4-diol dicyclohexanecarboxylate, hexahydrobenzo[1,3,2]dioxathiolan-2-oxide (1,2-cyclohexanediol, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, 2,2-dioxide-1,2-oxathiolan-4-yl acetate, etc.);

[0351] Oxalate diesters such as methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, propyl 2-propynyl oxalate, 2-propynyl vinyl oxalate, allyl 2-propynyl oxalate, di-2-propynyl oxalate, 2-butynylmethyl oxalate, 2-butynylethyl oxalate, 2-butynylpropyl oxalate, 2-butynyl vinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynylmethyl oxalate, 3-butynylethyl oxalate, 3-butynylpropyl oxalate, 3-butynyl vinyl oxalate, allyl 3-butynyl oxalate, and di-3-butynyl oxalate;

[0352] Phosphine oxides such as methyl(2-propynyl)(vinyl)phosphine oxide, divinyl(2-propynyl)phosphine oxide, di(2-propynyl)(vinyl)phosphine oxide, di(2-propenyl)2(-propynyl)phosphine oxide, di(2-propynyl)(2-propenyl)phosphine oxide, di(3-butenyl)(2-propynyl)phosphine oxide, and di(2-propynyl)(3-butenyl)phosphine oxide;

[0353] 2-propynyl methyl(2-propenyl)phosphinate, 2-propynyl 2-butenyl(methyl)phosphinate, 2-propynyl di(2-propenyl)phosphinate, 2-propynyl di(3-butenyl)phosphinate, 1,1-dimethyl-2-propynyl methyl(2-propenyl)phosphinate, 1,1-dimethyl-2-propynyl 2-butenyl(methyl)phosphinate, 1,1-dimethyl-2-propynyl di(2-propenyl)phosphinate, and Phosphinic acid esters such as 1,1-dimethyl-2-propynyl di(3-butenyl)phosphinate, 2-propenyl methyl(2-propynyl)phosphinate, 3-butenyl methyl(2-propynyl)phosphinate, 2-propenyl di(2-propynyl)phosphinate, 3-butenyl di(2-propynyl)phosphinate, 2-propynyl(2-propenyl)phosphinate, and 3-butenyl 2-propynyl(2-propenyl)phosphinate;

[0354] Methyl 2-propenyl phosphonate, methyl 2-butenyl phosphonate (2-propynyl), 2-propenylphosphonic acid (2-propynyl) (2-propenyl), 3-butenylphosphonic acid (3-butenyl) (2-propynyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-butenylphosphonic acid (1,1-dimethyl-2-propynyl) (methyl), 2-propenylphosphonic acid (1,1-dimethyl-2-propynyl) (2-propenyl), and 3-butenylphosphonic acid (3-butenyl) (1,1-dimethyl-2-propynyl), Phosphonic acid esters such as tylphosphonic acid (2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(2-propynyl), methylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), methylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl), ethylphosphonic acid (2-propynyl)(2-propenyl), ethylphosphonic acid (3-butenyl)(2-propynyl), ethylphosphonic acid (1,1-dimethyl-2-propynyl)(2-propenyl), and ethylphosphonic acid (3-butenyl)(1,1-dimethyl-2-propynyl);

[0355] Phosphate esters such as (methyl)(2-propenyl)(2-propynyl) phosphate, (ethyl)(2-propenyl)(2-propynyl) phosphate, (2-butenyl)(methyl)(2-propynyl) phosphate, (1,1-dimethyl-2-propynyl)(methyl)(2-propenyl) phosphate, (1,1-dimethyl-2-propynyl)(ethyl)(2-propenyl) phosphate, (2-butenyl)(1,1-dimethyl-2-propynyl)(methyl) phosphate, and (2-butenyl)(ethyl)(1,1-dimethyl-2-propynyl) phosphate;

[0356] Of these, compounds having an alkynyloxy group are preferred because they form a negative electrode film more stably in the electrolyte.

[0357] Furthermore, compounds such as 2-propynylmethyl carbonate, di-2-propynyl carbonate, 2-butyne-1,4-diol dimethyl dicarbonate, 2-propynyl acetate, 2-butyne-1,4-diol diacetate, methyl 2-propynyl oxalate, and di-2-propynyl oxalate are particularly preferred from the viewpoint of improving storage properties.

[0358] The compounds having the triple bond described above may be used individually or in any combination and ratio of two or more. There are no restrictions on the amount of the compound having the triple bond to be incorporated into the total electrolyte of this disclosure, and it is arbitrary as long as it does not significantly impair the effects of this disclosure. However, it is usually included in the electrolyte of this disclosure at a concentration of 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less. When the above range is met, the effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

[0359] In the electrolyte of this disclosure, an overcharge inhibitor can be used to effectively suppress battery rupture and ignition when an electrochemical device using the electrolyte enters an overcharged state or the like.

[0360] Overcharge prevention agents include biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, and other unsubstituted or alkyl-substituted terphenyl derivatives; partially hydrogenated unsubstituted or alkyl-substituted terphenyl derivatives; cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindan, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, t-butylbenzene, t-amylbenzene, t-hexylbenzene, anisole, and other aromatic compounds; 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, flu Examples include partially fluorinated compounds of the above aromatic compounds such as orotoluene and benzotrifluoride; fluorinated anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 1,6-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, and phenethylphenyl acetate; aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate; toluene derivatives such as toluene and xylene; and unsubstituted or alkyl-substituted biphenyl derivatives such as 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and o-cyclohexylbiphenyl. Among these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferred, as are diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindan, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, and methylphenyl carbonate. These may be used individually or in combination of two or more.When using two or more compounds in combination, it is particularly preferable, from the viewpoint of balancing overcharge prevention characteristics and high-temperature storage characteristics, to use a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, or at least one selected from oxygen-free aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, and t-amylbenzene, and at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran.

[0361] The electrolyte of this disclosure may further contain compound (5) represented by general formula (5).

[0362] General formula (5): [ka] (In the formula, A a+ is a metal ion, hydrogen ion, or onium ion. a is an integer from 1 to 3, b is an integer from 1 to 3, p is b / a, n203 is an integer from 1 to 4, n201 is an integer from 0 to 8, n202 is 0 or 1, Z 201 These are transition metals, elements of group III, IV, or V of the periodic table. X 201 This includes O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (alkylene groups, halogenated alkylene groups, arylene groups, and halogenated arylene groups may have substituents and heteroatoms in their structure, and when n202 is 1 and n203 is 2 to 4, there are X atoms in n203). 201 (These may be combined.) L 201 This includes halogen atoms, cyano groups, C1-C10 alkyl groups, C1-C10 halogenated alkyl groups, C6-C20 aryl groups, C6-C20 halogenated aryl groups (alkylene groups, halogenated alkylene groups, arylene groups, and halogenated arylene groups may have substituents and heteroatoms in their structure, and when n201 is 2-8, there are n201 L201 (These may each join to form a ring) or -Z 203 Y 203 . Y 201 , Y 202 and Z 203 These are O, S, and NY, respectively, and are independent of each other. 204 , hydrocarbon group or fluorinated hydrocarbon group. Y 203 and Y 204 Each of these is independently H, F, a C1-C10 alkyl group, a C1-C10 halogenated alkyl group, a C6-C20 aryl group, or a C6-C20 halogenated aryl group (alkyl groups, halogenated alkyl groups, aryl groups, and halogenated aryl groups may have substituents or heteroatoms in their structure, Y 203 or Y 204 If multiple such elements exist, they may combine to form a ring.

[0363] A a+ Examples include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions, barium ions, cesium ions, silver ions, zinc ions, copper ions, cobalt ions, iron ions, nickel ions, manganese ions, titanium ions, lead ions, chromium ions, vanadium ions, ruthenium ions, yttrium ions, lanthanide ions, actinide ions, tetrabutylammonium ions, tetraethylammonium ions, tetramethylammonium ions, triethylmethylammonium ions, triethylammonium ions, pyridinium ions, imidazolium ions, hydrogen ions, tetraethylphosphonium ions, tetramethylphosphonium ions, tetraphenylphosphonium ions, triphenylsulfonium ions, and triethylsulfonium ions.

[0364] When used in applications such as electrochemical devices, A a+ Lithium ions, sodium ions, magnesium ions, tetraalkylammonium ions, and hydrogen ions are preferred, with sodium ions being particularly preferred. a+The valence a of the cation is an integer between 1 and 3. If it is greater than 3, the crystal lattice energy increases, which makes it difficult to dissolve in the solvent. Therefore, if solubility is required, 1 is more preferable. Similarly, the valence b of the anion is an integer between 1 and 3, with 1 being particularly preferable. The constant p, which represents the ratio of the cation to the anion, is necessarily determined by the ratio of their valencies b / a.

[0365] Next, we will explain the ligand portion of general formula (5). In this specification, Z in general formula (5) 201 The organic or inorganic part that is bonded to the molecule is called a ligand.

[0366] Z 201 The element is preferably Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf, or Sb, and more preferably Al, B, or P.

[0367] X 201 represents O, S, an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene and arylene groups may have substituents and heteroatoms in their structure. Specifically, instead of hydrogen atoms on the alkylene and arylene groups, halogen atoms, linear or cyclic alkyl groups, aryl groups, alkenyl groups, alkoxy groups, aryloxy groups, sulfonyl groups, amino groups, cyano groups, carbonyl groups, acyl groups, amide groups, and hydroxyl groups may be present as substituents, or nitrogen, sulfur, and oxygen may be introduced instead of carbon atoms on the alkylene and arylene. Also, when n202 is 1 and n203 is 2 to 4, the X atoms in n203 201 These components may be bonded together. An example of such a ligand is ethylenediaminetetraacetic acid.

[0368] L 201This includes halogen atoms, cyano groups, C1-C10 alkyl groups, C1-C10 halogenated alkyl groups, C6-C20 aryl groups, C6-C20 halogenated aryl groups, or -Z 203 Y 203 (Z 203 , Y 203 (This will be explained later.) Here, alkyl and aryl groups also represent X 201 Similarly, the structure may have substituents and heteroatoms, and when n201 is 2 to 8, there are n201 L 201 Each of them may be joined together to form a ring. 201 Preferably, the element is a fluorine atom or a cyano group. In the case of a fluorine atom, the solubility and dissociation of the salt of the anionic compound are improved, and consequently, the ionic conductivity is improved. Furthermore, oxidation resistance is improved, which can suppress the occurrence of side reactions.

[0369] Y 201 , Y 202 and Z 203 These are O, S, and NY, respectively, and are independent of each other. 204 , represents a hydrocarbon group or a fluorinated hydrocarbon group. 201 and Y 202 is O, S or NY 204 It is preferable that it is O, and more preferably that it is O. A characteristic of compound (5) is that it contains Y in the same ligand. 201 and Y 202 Z by 201 Because of the bond with Z 201 It forms a chelate structure. This chelate effect improves the heat resistance, chemical stability, and hydrolysis resistance of this compound. The constant n202 in this ligand is 0 or 1, but in particular, when it is 0, the chelate ring becomes a five-membered ring, so the chelate effect is most strongly exhibited and stability is increased, which is preferable. In this specification, a fluorinated hydrocarbon group is defined as a hydrocarbon group in which at least one hydrogen atom is replaced by a fluorine atom.

[0370] Y 203 and Y 204Each of these is independently H, F, a C1-C10 alkyl group, a C1-C10 halogenated alkyl group, a C6-C20 aryl group, or a C6-C20 halogenated aryl group, and these alkyl and aryl groups may have substituents or heteroatoms in their structure, and Y 203 or Y 204 If multiple such elements exist, they may combine to form a ring.

[0371] Furthermore, the constant n203 related to the number of ligands described above is an integer between 1 and 4, preferably 1 or 2, and more preferably 2. Also, the constant n201 related to the number of ligands described above is an integer between 0 and 8, preferably 0 to 4, and more preferably 0, 2, or 4. Moreover, it is preferable that when n203 is 1, n201 is 2, and when n203 is 2, n201 is 0.

[0372] In general formula (5), alkyl groups, alkyl halides, aryl groups, and aryl halides also include those having other functional groups such as branching, hydroxyl groups, and ether bonds.

[0373] Compound (5) has the general formula: [ka] (In the formula, A a+ a, b, p, n201, Z 201 and L 201 The compound shown above is, or the general formula: [ka] (In the formula, A a+ a, b, p, n201, Z 201 and L 201 It is preferable that the compound is as shown above.

[0374] Compound (5) is sodium oxalatoborate salts, and is given by the following formula: [ka] Sodium bis(oxalato)borate (NaBOB), represented by the following formula: [ka] Sodium difluorooxalatoborate (NaDFOB), represented by the following formula: [ka] Sodium difluorooxalatophosphanite (NaDFOP), represented by the following formula: [ka] Sodium tetrafluorooxalatophosphanite (NaTFOP), represented by the following formula: [ka] Examples include sodium bis(oxalato)difluorophosphanite, as shown in the formula.

[0375] Compound (5) also includes dicarboxylic acid complex salts in which the central complex element is boron, such as sodium bis(malonato)borate, sodium difluoro(malonato)borate, sodium bis(methylmalonato)borate, sodium difluoro(methylmalonato)borate, sodium bis(dimethylmalonato)borate, and sodium difluoro(dimethylmalonato)borate.

[0376] Examples of compound (5) also include dicarboxylic acid complex salts in which the central complex element is phosphorus, such as sodium tris(oxalato)phosphate, sodium tris(malonato)phosphate, sodium difluorobis(malonato)phosphate, sodium tetrafluoro(malonato)phosphate, sodium tris(methylmalonato)phosphate, sodium difluorobis(methylmalonato)phosphate, sodium tetrafluoro(methylmalonato)phosphate, sodium tris(dimethylmalonato)phosphate, sodium difluorobis(dimethylmalonato)phosphate, and sodium tetrafluoro(dimethylmalonato)phosphate.

[0377] Compound (5) also includes dicarboxylic acid complex salts in which the central element of the complex is aluminum, such as NaAl(C2O4)2 and NaAlF2(C2O4).

[0378] Among these, sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium tris(oxalato)phosphate, sodium difluorobis(oxalato)phosphate, and sodium tetrafluoro(oxalato)phosphate are more preferably used due to their availability and their ability to contribute to the formation of stable film-like structures. Sodium bis(oxalato)borate is particularly preferred as compound (5).

[0379] The content of compound (5) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, more preferably 10% by mass or less, and more preferably 3% by mass or less, relative to the solvent, in order to obtain even better cycling characteristics.

[0380] The electrolyte used in this disclosure may be a carboxylic acid anhydride (except for compound (2)). The compound (6) represented by the following general formula (6) is preferred as the carboxylic acid anhydride. The method for producing the carboxylic acid anhydride is not particularly limited, and it can be produced by arbitrarily selecting any known method. General formula (6):

[0381] [ka] (In general formula (6), R 61 , R 62 Each of these independently represents a hydrocarbon group having 1 to 15 carbon atoms, which may have substituents.

[0382] R 61 , R 62 The type of monovalent hydrocarbon group is not particularly limited. For example, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain an unsaturated bond (carbon-carbon double bond or carbon-carbon triple bond). Furthermore, the aliphatic hydrocarbon group may be linear or cyclic, and if linear, it may be straight or branched. Moreover, it may be a combination of a linear and a cyclic structure. Note that R 61 and R 62 These may be identical or different from one another.

[0383] Also, R 61 , R 62 When the hydrocarbon group has substituents, the type of substituent is not particularly limited as long as it does not contradict the spirit of this disclosure, but examples include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms, and preferably fluorine atoms. Other substituents besides halogen atoms include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, and preferably cyano groups and carbonyl groups. 61 , R 62 The hydrocarbon group may have only one of these substituents or may have two or more. If it has two or more substituents, the substituents may be the same or different from one another.

[0384] R 61 , R62 The number of carbon atoms in each hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 12 or less, more preferably 10 or less, and even more preferably 9 or less. 61 and R 62 When R is bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms in that divalent hydrocarbon group is usually 1 or more, and usually 15 or less, preferably 13 or less, more preferably 10 or less, and even more preferably 8 or less. 61 , R 62 If the hydrocarbon group has a substituent containing a carbon atom, then the R includes that substituent. 61 , R 62 It is preferable that the total number of carbon atoms satisfies the above range.

[0385] Next, specific examples of the above compound (6) will be described. In the following examples, "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure, to the extent that it does not contradict the spirit of this disclosure. Examples include dimers, trimers, and tetramers consisting of multiple acid anhydrides, or isostructural isomers having branched chains but the same number of carbon atoms in the substituents, or those in which the substituents are attached to the acid anhydride at different sites.

[0386] First, R 61 , R 62 Specific examples of acid anhydrides that are identical are listed below.

[0387] R 61 , R 62 Specific examples of acid anhydrides in which the chain alkyl group is included are acetic anhydride, propionic anhydride, butanoic anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2,2-dimethylbutanoic anhydride, 2,3-dimethylbutanoic anhydride, 3,3-dimethylbutanoic anhydride, 2,2,3-trimethylbutanoic anhydride, 2,3,3-trimethylbutanoic anhydride, 2,2,3,3-tetramethylbutanoic anhydride, 2-ethylbutanoic anhydride, and their analogues.

[0388] R 61 , R 62 Specific examples of acid anhydrides in which the parent molecule is a cyclic alkyl group include cyclopropanecarboxylic acid anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, and their analogues.

[0389] R 61 , R 62 Specific examples of acid anhydrides in which the parent group is an alkenyl group include acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3-butenoic acid anhydride, 2-methyl-3-butenoic acid anhydride, 2,2-dimethyl-3-butenoic acid anhydride, 3-methyl-3-thenic acid anhydride, 2-methyl-3-methyl-3-butenoic acid anhydride, 2,2-dimethyl-3-methyl-3-butenoic acid anhydride, 3-pentenoic acid anhydride, 4-pentenoic acid anhydride, 2-cyclopentenecarboxylic acid anhydride, 3-cyclopentenecarboxylic acid anhydride, 4-cyclopentenecarboxylic acid anhydride, etc., and their analogues.

[0390] R 61 , R 62 Specific examples of acid anhydrides in which the parent group is an alkynyl group include propic anhydride, 3-phenylpropic anhydride, 2-butic anhydride, 2-pentic anhydride, 3-butic anhydride, 3-pentic anhydride, 4-pentic anhydride, and their analogues.

[0391] R 61 , R 62 Specific examples of acid anhydrides in which the group is an aryl group include benzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-ethylbenzoic acid anhydride, 4-tert-butylbenzoic acid anhydride, 2-methylbenzoic acid anhydride, 2,4,6-trimethylbenzoic acid anhydride, 1-naphthalenecarboxylic acid anhydride, 2-naphthalenecarboxylic acid anhydride, and their analogues.

[0392] Also, R 61 , R 62 Examples of acid anhydrides substituted with halogen atoms are listed below, primarily examples of acid anhydrides substituted with fluorine atoms. However, acid anhydrides obtained by substituting some or all of these fluorine atoms with chlorine atoms, bromine atoms, or iodine atoms are also included in the list of exemplary compounds.

[0393] R 61 , R 62 Examples of acid anhydrides in which the linear alkyl group is substituted with a halogen atom include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3-tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride, and their analogues.

[0394] R 61 , R 62 Examples of acid anhydrides in which the alkyl group is a cyclic alkyl group substituted with a halogen atom include 2-fluorocyclopentanecarboxylic acid anhydride, 3-fluorocyclopentanecarboxylic acid anhydride, 4-fluorocyclopentanecarboxylic acid anhydride, and their analogues.

[0395] R 61 , R 62Examples of acid anhydrides in which the nucleotide is an alkenyl group substituted with a halogen atom include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3-tris(trifluoromethyl)acrylic anhydride, and 2-(4-fluoro Examples include 2,3-(4-fluorophenyl)acrylic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butenoic acid anhydride, 2,2-difluoro-3-butenoic acid anhydride, 3-fluoro-2-butenoic acid anhydride, 4-fluoro-3-butenoic acid anhydride, 3,4-difluoro-3-butenoic acid anhydride, 3,3,4-trifluoro-3-butenoic acid anhydride, and their analogues.

[0396] R 61 , R 62 Examples of acid anhydrides in which the alkynyl group is substituted with a halogen atom include 3-fluoro-2-propynic anhydride, 3-(4-fluorophenyl)-2-propynic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propynic anhydride, 4-fluoro-2-butynic anhydride, 4,4-difluoro-2-butynic anhydride, 4,4,4-trifluoro-2-butynic anhydride, and their analogues.

[0397] R 61 , R 62 Examples of acid anhydrides in which the aryl group is substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and their analogues.

[0398] R 61 , R 62Examples of acid anhydrides having substituents with functional groups such as esters, nitriles, ketones, and ethers include methoxyformic anhydride, ethoxyformic anhydride, methyl oxalic anhydride, ethyl oxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and their analogues.

[0399] Next, R 61 , R 62 The following are specific examples of acid anhydrides that are different from each other.

[0400] R 61 , R 62 The examples listed above, as well as all combinations of their related forms, are possible, but some representative examples are given below.

[0401] Examples of combinations of linear alkyl groups include propionic anhydride acetate, butanoic anhydride acetate, propionic butanoic anhydride, and 2-methylpropionic anhydride acetate.

[0402] Examples of combinations of linear alkyl groups and cyclic alkyl groups include cyclopentanoic anhydride acetate, cyclohexanoic anhydride acetate, and cyclopentanoic propionic anhydride acetate.

[0403] Examples of combinations of linear alkyl groups and alkenyl groups include acrylic anhydride acetate, 3-methylacrylic anhydride acetate, 3-butenic acid anhydride acetate, and propionic acid anhydride acetate.

[0404] Examples of combinations of linear alkyl groups and alkynyl groups include acetic acid propynic anhydride, acetic acid 2-butic anhydride, acetic acid 3-butic anhydride, acetic acid 3-phenylpropynic anhydride, propionic acid propynic anhydride, and the like.

[0405] Examples of combinations of linear alkyl groups and aryl groups include benzoic acid anhydride acetate, methylbenzoic acid anhydride acetate, 1-naphthalenecarboxylic acid anhydride acetate, and propionic acid benzoate anhydride.

[0406] Examples of combinations of linear alkyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride, trifluoroacetic anhydride, 4-fluorobenzoic anhydride, fluoroacetic acid propionic anhydride, alkyl oxalic acid anhydride, 2-cyanoacetic acid anhydride, 2-oxopropionic acid anhydride, methoxyacetic acid anhydride, methoxyacetic acid propionic anhydride, and the like.

[0407] Examples of combinations of cyclic alkyl groups include cyclopentanoic acid and cyclohexanoic anhydride, among others.

[0408] Examples of combinations of cyclic alkyl groups and alkenyl groups include cyclopentanoic anhydride acrylate, cyclopentanoic anhydride 3-methylacrylate, cyclopentanoic anhydride 3-butenoic anhydride, and cyclohexanoic anhydride acrylate.

[0409] Examples of combinations of cyclic alkyl groups and alkynyl groups include cyclopentanoic anhydride propynate, cyclopentanoic anhydride 2-butyrate, and cyclohexanoic anhydride propynate.

[0410] Examples of combinations of cyclic alkyl groups and aryl groups include cyclopentanoic anhydride benzoate, cyclopentanoic anhydride 4-methylbenzoic acid, and cyclohexanoic anhydride benzoate.

[0411] Examples of combinations of cyclic alkyl groups and hydrocarbon groups having functional groups include cyclopentanoic anhydride fluoroacetate, trifluoroacetic anhydride cyclopentanoic acid, 2-cyanoacetic anhydride cyclopentanoic acid, methoxyacetic anhydride cyclopentanoic acid, and fluoroacetic anhydride cyclohexanoic acid.

[0412] Examples of combinations of alkenyl groups include 2-methylacrylic anhydride acrylate, 3-methylacrylic anhydride acrylate, 3-butenic anhydride acrylate, and 3-methylacrylic anhydride 2-methylacrylic acid.

[0413] Examples of combinations of alkenyl and alkynyl groups include acrylic acid propynic anhydride, acrylic acid 2-butynic anhydride, and 2-methylacrylic acid propynic anhydride.

[0414] Examples of combinations of alkenyl and aryl groups include acrylate benzoic anhydride, 4-methylbenzoic anhydride, and 2-methylacrylate benzoic anhydride.

[0415] Examples of combinations of alkenyl groups and hydrocarbon groups having functional groups include fluoroacetic anhydride of acrylate, trifluoroacetic anhydride of acrylate, 2-cyanoacetic anhydride of acrylate, methoxyacetic anhydride of acrylate, fluoroacetic anhydride of 2-methylacrylate, and the like.

[0416] Examples of combinations of alkynyl groups include 2-butyric anhydride of propyic acid, 3-butyric anhydride of propyic acid, and 3-butyric anhydride of 2-butyric acid.

[0417] Examples of combinations of alkynyl and aryl groups include benzoic acid propynic anhydride, 4-methylbenzoic acid propynic anhydride, and benzoic acid 2-butynic anhydride.

[0418] Examples of combinations of an alkynyl group and a hydrocarbon group having a functional group include fluoroacetic anhydride of propynate, trifluoroacetic anhydride of propynate, 2-cyanoacetic anhydride of propynate, methoxyacetic anhydride of propynate, fluoroacetic anhydride of 2-butyrate, and the like.

[0419] Examples of combinations of aryl groups include 4-methylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, and 1-naphthalenecarboxylic anhydride of 4-methylbenzoic acid.

[0420] Examples of combinations of aryl groups and hydrocarbon groups having functional groups include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, 4-methylbenzoic acid fluoroacetic anhydride, and the like.

[0421] Examples of combinations of hydrocarbon groups having functional groups include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, trifluoroacetic acid 2-cyanoacetic anhydride, and the like.

[0422] Among the acid anhydrides forming the above chain structure, preferred are acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic acid anhydride, cyclohexanecarboxylic acid anhydride, etc., acrylic acid anhydride, 2-methylacrylic acid anhydride, 3-methylacrylic acid anhydride, 2,3-dimethylacrylic acid anhydride, 3,3-dimethylacrylic acid anhydride, 3-butenoic acid anhydride, 2-methyl-3-butenoic acid anhydride, propynic acid anhydride, 2-butic acid anhydride, benzoic acid anhydride, 2-methylbenzoic acid anhydride, 4-methylbenzoic acid anhydride, 4-tert-butylbenzoic acid anhydride, trifluoroacetic acid anhydride, 3,3,3-trif The anhydride is oolopropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, and ethoxyformic anhydride; more preferably, the anhydride is acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, and ethoxyformic anhydride.

[0423] These compounds are preferable in that they can form a durable film by appropriately bonding with lithium oxalate salts, thereby improving charge-discharge rate characteristics, input / output characteristics, and impedance characteristics, especially after durability testing.

[0424] There are no restrictions on the molecular weight of the carboxylic acid anhydride mentioned above; it can be any molecular weight as long as it does not significantly impair the effects of this disclosure. However, it is usually 90 or more, preferably 95 or more, while it is usually 300 or less, preferably 200 or less. When the molecular weight of the carboxylic acid anhydride is within the above range, the increase in viscosity of the electrolyte can be suppressed, and the film density can be optimized, thereby appropriately improving durability.

[0425] Furthermore, there are no particular restrictions on the method of producing the above-mentioned carboxylic acid anhydrides, and they can be produced by any known method. Any one of the carboxylic acid anhydrides described above may be included alone in the non-aqueous electrolyte of this disclosure, or two or more may be included in any combination and ratio.

[0426] Furthermore, there are no particular restrictions on the content of the above-mentioned carboxylic acid anhydride in the electrolyte of this disclosure, and it is optional as long as it does not significantly impair the effects of this disclosure. However, it is desirable to include it in the electrolyte of this disclosure at a concentration of usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less. When the content of the carboxylic acid anhydride is within the above range, the effect of improving cycle characteristics is more likely to occur, and the reactivity is suitable, so the battery characteristics are more likely to improve.

[0427] Other known additives may be used in the electrolyte of this disclosure. Other additives include hydrocarbon compounds such as pentane, heptane, octane, nonane, decane, cycloheptane, benzene, furan, naphthalene, 2-phenylbicyclohexyl, cyclohexane, 2,4,8,10-tetraoxaspiro[5.5]undecane, and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; Fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, monofluorobenzene, 1-fluoro-2-cyclohexylbenzene, 1-fluoro-4-tert-butylbenzene, 1-fluoro-3-cyclohexylbenzene, 1-fluoro-2-cyclohexylbenzene, and fluorinated biphenyls; Carbonate compounds such as erythritol carbonate, spirobis-dimethylene carbonate, and methoxyethyl-methyl carbonate; Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxopentadecane, ethoxymethoxyethane, trimethoxymethane, glyme, and ethyl monoglyme; Ketone compounds such as dimethyl ketone, diethyl ketone, and 3-pentanone; Acid anhydrides such as 2-allyl succinic anhydride; Ester compounds such as dimethyl oxalate, diethyl oxalate, ethylmethyl oxalate, di(2-propynyl) oxalate, methyl 2-propynyl oxalate, dimethyl succinate, di(2-propynyl) glutarate, methyl formate, ethyl formate, 2-propynyl formate, 2-butyne-1,4-diyldiformate, 2-propynyl methacrylate, and dimethyl malonate; Amide compounds such as acetamide, N-methylformamide, N,N-dimethylformamide, and N,N-dimethylacetamide; Ethylene sulfate, vinylene sulfate, ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, diphenyl sulfone, N,N-dimethylmethanesulfonamide, N,N-diethylmethanesulfonamide, methyl vinylsulfonate, ethyl vinylsulfonate, allyl vinylsulfonate, propargyl vinylsulfonate, methyl allylsulfonate, ethyl allylsulfonate, allyl allylsulfonate, propargyl allylsulfonate, 1,2-bis(vinylsulfonyloxy)ethane, propanedisulfonic anhydride, sulfobutyric anhydride, sulfobenzoic anhydride, sulfopropionic anhydride, ethanedisulfonic anhydride, methylenemethanedisulfonate, 2-propynyl methanesulfonate, pentenesulfite, pentafluorophenylmethanesulfonate, propylene sulfate, propylene sulfite, propane Insalton, butylene sulfite, butane-2,3-diyldimethanesulfonate, 2-butyne-1,4-diyldimethanesulfonate, 2-propynyl vinylsulfonic acid, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, 2-(methanesulfonyloxy)propionic acid 2-propynyl, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxy Sulfur-containing compounds such as 3-sulfo-propionic anhydride, trimethylene methane disulfonate, 2-methyltetrahydrofuran, trimethylene methane disulfonate, tetramethylene sulfoxide, dimethyl methane disulfonate, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, methyl ethylenebissulfonate, ethyl ethylenebissulfonate, ethylene sulfate, and thiophene 1-oxide; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide, nitromethane, nitroethane, and ethylenediamine; Trimethyl phosphate, triethyl phosphate, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, diethyl ethyl phosphonoethyl acetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphin oxide, triethylphosphin oxide, bis(2,2-difluoroethyl) phosphate, bis(2,2,3,3-tetrafluoroethyl) phosphate Oropropyl) 2,2,2-trifluoroethyl, bis(2,2,2-trifluoroethyl)methyl phosphate, bis(2,2,2-trifluoroethyl)ethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2-difluoroethyl phosphate, bis(2,2,2-trifluoroethyl) 2,2,3,3-tetrafluoropropyl, tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, tris(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate, trioctyl phosphate, 2-phenyl phosphate Nylphenyldimethyl, 2-phenylphenyldiethyl phosphate, (2,2,2-trifluoroethyl)(2,2,3,3-tetrafluoropropyl)methyl phosphate, methyl 2-(dimethoxyphosphoryl) acetate, methyl 2-(dimethylphosphoryl) acetate, methyl 2-(diethoxyphosphoryl) acetate, methyl 2-(diethylphosphoryl) acetate, methyl methylenebisphosphonate, ethyl methylenebisphosphonate, methyl ethylenebisphosphonate, ethyl ethylenebisphosphonate, methyl butylenebisphosphonate Phosphorus-containing compounds such as ethyl butylenebisphosphonate, 2-propynyl 2-(dimethoxyphosphoryl) acetate, 2-propynyl 2-(dimethylphosphoryl) acetate, 2-propynyl 2-(diethoxyphosphoryl) acetate, 2-propynyl 2-(diethylphosphoryl) acetate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and trimethylsilyl polyphosphate; Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; Silane compounds such as dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titaniumtetrakis(trimethylsiloxide), titaniumtetrakis(triethylsiloxide), and tetramethylsilane; These are some examples. These can be used individually or in combination of two or more. By adding these additives, the volume retention characteristics and cycle characteristics after high-temperature storage can be improved. Among the other additives mentioned above, phosphorus-containing compounds are preferred, with tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite being particularly preferred.

[0428] The amount of other additives is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure. Preferably, the amount of other additives is 0.01% by mass or more, and 5% by mass or less, in 100% by mass of the electrolyte. Within this range, the effects of the other additives can be easily expressed, and situations such as a decrease in battery characteristics, such as high-load discharge characteristics, can be easily avoided. More preferably, the amount of other additives is 0.1% by mass or more, even more preferably 0.2% by mass or more, even more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0429] The electrolyte of this disclosure may further contain, to the extent that it does not impair the effects of this disclosure, cyclic and linear carboxylic acid esters, ether compounds, nitrogen-containing compounds, boron-containing compounds, organosilicon-containing compounds, flame retardants, surfactants, high dielectric additives, cycle and rate characteristic improvers, sulfone compounds, and the like as additives.

[0430] Examples of the above-mentioned cyclic carboxylic acid esters include those with a total of 3 to 12 carbon atoms in their structural formula. Specifically, examples include gamma-butyrolactone, gamma-valerolactone, gamma-macarolactone, epsilon-caprolactone, and 3-methyl-γ-butyrolactone. Among these, gamma-butyrolactone is particularly preferred from the viewpoint of improving the properties of electrochemical devices due to an improved degree of sodium ion dissociation.

[0431] The amount of cyclic carboxylic acid ester used as an additive is usually preferably 0.1% by mass or more, more preferably 1% by mass or more, per 100% by mass of the solvent. Within this range, the electrical conductivity of the electrolyte is improved, making it easier to improve the high-current discharge characteristics of the electrochemical device. Alternatively, the amount of cyclic carboxylic acid ester used is preferably 10% by mass or less, more preferably 5% by mass or less. By setting such an upper limit, the viscosity of the electrolyte is kept within an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and the high-current discharge characteristics of the electrochemical device are made easier to achieve within a good range.

[0432] Furthermore, fluorinated cyclic carboxylic acid esters (fluorinated lactones) can also be suitably used as the above-mentioned cyclic carboxylic acid esters. Examples of fluorinated lactones include those of the following formula (C):

[0433] [ka]

[0434] (In the formula, X 15 ~X 20 The elements are the same or different, and all are -H, -F, -Cl, -CH3, or fluorinated alkyl groups; however, X 15 ~X 20 (At least one of them is a fluorinated alkyl group.) Examples include fluorine-containing lactones shown as follows.

[0435] X 15 ~X 20Examples of fluorinated alkyl groups include -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, and -CF(CF3)2. -CH2CF3 and -CH2CF2CF3 are preferred due to their high oxidation resistance and safety-enhancing effects.

[0436] X 15 ~X 20 If at least one of them is a fluorinated alkyl group, then -H, -F, -Cl, -CH3 or a fluorinated alkyl group is X 15 ~X 20 The substitution may occur at only one location or at multiple locations. Preferably, there are 1 to 3 locations, and more preferably 1 to 2 locations, from the viewpoint of good solubility of the electrolyte salt.

[0437] The substitution position of the fluorinated alkyl group is not particularly limited, but X is chosen because it yields a good synthesis yield. 17 and / or X 18 However, especially X 17 or X 18 It is preferable that X is a fluorinated alkyl group, particularly -CH2CF3 or -CH2CF2CF3. 15 ~X 20 The element is -H, -F, -Cl, or CH3, and -H is particularly preferred due to its good solubility as an electrolyte salt.

[0438] In addition to those shown in the above formula, other examples of fluorinated lactones include, for example, the following formula (D):

[0439] [ka]

[0440] (In the formula, A and B are either CX) 226 X 227 (X 226 and X 227(These are the same or different alkylene groups, which may have -H, -F, -Cl, -CF3, -CH3, or a hydrogen atom substituted with a halogen atom, or contain a heteroatom in the chain), and the other is an oxygen atom; Rf 12 X is a fluorinated alkyl group or fluorinated alkoxy group which may have an ether linkage; 221 and X 222 They are the same or different, and all are -H, -F, -Cl, -CF3, or CH3;X 223 ~X 225 These alkyl groups may be the same or different, and may have -H, -F, -Cl, or hydrogen atoms substituted with halogen atoms, or may contain heteroatoms in the chain; n=0 or 1) Examples include fluorine-containing lactones, as shown in [reference].

[0441] The fluorine-containing lactone represented by formula (D) is shown in formula (E):

[0442] [ka]

[0443] (In the formula, A, B, Rf 12 , X 221 , X 222 and X 223 (This is the same as equation (D)) The five-membered ring structure shown is preferred because it is easy to synthesize and has good chemical stability. Furthermore, the combination of A and B yields the following formula (F):

[0444] [ka]

[0445] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 (This is the same as equation (D)) The fluorine-containing lactone shown by and the following formula (G):

[0446] [ka]

[0447] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 (This is the same as equation (D)) There are fluorine-containing lactones, as shown by [this symbol].

[0448] Among these, the characteristics of the electrolyte in this disclosure are particularly improved by its ability to exhibit excellent properties such as high dielectric constant and high dielectric strength, as well as by its good solubility of the electrolyte salt and reduction of internal resistance.

[0449] [ka] These are some examples. By incorporating fluorinated cyclic carboxylic acid esters, effects such as improved ionic conductivity, enhanced safety, and improved stability at high temperatures can be obtained.

[0450] Examples of the above-mentioned chain-like carboxylic acid esters include those with a total of 3 to 7 carbon atoms in their structural formula. Specifically, examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isobutyl propionate, n-butyl propionate, methyl butyrate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, and isopropyl isobutyrate.

[0451] Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, and ethyl butyrate are preferred from the viewpoint of improving ionic conductivity by reducing viscosity.

[0452] The above ether compounds are preferably linear ethers having 2 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms. Examples of chain-like ethers having 2 to 10 carbon atoms include dimethyl ether, diethyl ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, diethoxymethane, dimethoxyethane, methoxyethoxyethane, diethoxyethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol, diethylene glycol dimethyl ether, pentaethylene glycol, triethylene glycol dimethyl ether, triethylene glycol, tetraethylene glycol, tetraethylene glycol dimethyl ether, and diisopropyl ether.

[0453] Furthermore, fluorinated ethers can also be suitably used as the ether compound. The above fluorinated ether is given by the following general formula (I): Rf 3 -O-Rf 4 (I) (In the formula, Rf 3 and Rf 4 They are the same or different, and are alkyl groups having 1 to 10 carbon atoms or fluorinated alkyl groups having 1 to 10 carbon atoms. However, Rf 3 and Rf 4 At least one of them is a fluorinated alkyl group. One example is fluorinated ether(I), represented by [formula]. By including fluorinated ether(I), the flame retardancy of the electrolyte is improved, as well as its stability and safety at high temperatures and high voltages.

[0454] In the above general formula (I), Rf 3 and Rf 4At least one of them should be a fluorinated alkyl group having 1 to 10 carbon atoms, but from the viewpoint of further improving the flame retardancy of the electrolyte and its stability and safety at high temperature and high voltage, Rf 3 and Rf 4 However, it is preferable that both are fluorinated alkyl groups having 1 to 10 carbon atoms. In this case, Rf 3 and Rf 4 They may be the same, or they may be different from one another. Among them, Rf 3 and Rf 4 However, they are the same or different, Rf 3 is a fluorinated alkyl group having 3 to 6 carbon atoms, and Rf 4 It is more preferable that the element is a fluorinated alkyl group having 2 to 6 carbon atoms.

[0455] Rf 3 and Rf 4 If the total number of carbon atoms is too low, the boiling point of the fluorinated ether will be too low, and Rf 3 or Rf 4 If the number of carbon atoms is too high, the solubility of the electrolyte salt decreases, negatively affecting its compatibility with other solvents, and the viscosity increases, thus reducing its rate characteristics. 3 The number of carbon atoms is 3 or 4, Rf 4 When the number of carbon atoms is 2 or 3, it is advantageous in that it has excellent boiling point and rate characteristics.

[0456] The above-mentioned fluorinated ether (I) preferably has a fluorine content of 40 to 75% by mass. When the fluorine content is within this range, it exhibits a particularly excellent balance between non-flammability and compatibility. It is also preferable in terms of good oxidation resistance and safety. The lower limit of the fluorine content is more preferably 45% by mass, even more preferably 50% by mass, and particularly preferably 55% by mass. The upper limit is more preferably 70% by mass, and even more preferably 66% by mass. The fluorine content of fluorinated ether(I) is calculated based on the structural formula of fluorinated ether(I) using the formula {(number of fluorine atoms × 19) / molecular weight of fluorinated ether(I)} × 100 (%).

[0457] Rf 3 Examples include CF3CF2CH2-, CF3CFHCF2-, HCF2CF2CF2-, HCF2CF2CH2-, CF3CF2CH2CH2-, CF3CFHCF2CH2-, HCF2CF2CF2CF2-, HCF2CF2CF2CH2-, HCF2CF2CH2CH2-, HCF2CF(CF3)CH2-, etc. Also, Rf 4 Examples include -CH2CF2CF3, -CF2CFHCF3, -CF2CF2CF2H, -CH2CF2CF2H, -CH2CH2CF2CF3, -CH2CF2CFHCF3, -CF2CF2CF2CF2H, -CH2CF2CF2CF2H, -CH2CH2CF2CF2H, -CH2CF(CF3)CF2H, -CF2CF2H, -CH2CF2H, -CF2CH3, etc.

[0458] Specific examples of the above fluorinated ether (I) include, for example, HCF2CF2CH2OCF2CF2H, CF3CF2CH2OCF2CF2H, HCF2CF2CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, and C6F 13 OCH3, C6F 13 OC2H5, C8F 17 O CH3, C8F 17 Examples include OC2H5, CF3CFHCF2CH(CH3)OCF2CFHCF3, HCF2CF2OCH(C2H5)2, HCF2CF2OC4H9, HCF2CF2OCH2CH(C2H5)2, and HCF2CF2OCH2CH(CH3)2.

[0459] In particular, those containing HCF2- or CF3CFH- at one or both ends exhibit excellent polarizability and can yield fluorinated ether(I) with a high boiling point. The boiling point of fluorinated ether(I) is preferably 67 to 120°C, more preferably 80°C or higher, and even more preferably 90°C or higher.

[0460] Examples of such fluorinated ethers (I) include one or more types such as CF3CH2OCF2CFHCF3, CF3CF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CFHCF3, HCF2CF2CH2OCH2CF2CF2H, CF3CFHCF2CH2OCF2CFHCF3, HCF2CF2CH2OCF2CF2H, and CF3CF2CH2OCF2CF2H. In particular, it is preferable to select at least one from the group consisting of HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C), CF3CF2CH2OCF2CFHCF3 (boiling point 82°C), HCF2CF2CH2OCF2CF2H (boiling point 92°C), and CF3CF2CH2OCF2CF2H (boiling point 68°C), as it is advantageous in terms of its high boiling point, compatibility with other solvents, and good solubility of electrolyte salts. It is more preferable to select at least one from the group consisting of HCF2CF2CH2OCF2CFHCF3 (boiling point 106°C) and HCF2CF2CH2OCF2CF2H (boiling point 92°C).

[0461] Examples of cyclic ethers having 3 to 6 carbon atoms include 1,2-dioxane, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, metaformaldehyde, 2-methyl-1,3-dioxolane, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-(trifluoroethyl)dioxolane, 2,2-bis(trifluoromethyl)-1,3-dioxolane, and their fluorinated compounds. Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, and crown ether are preferred because they have high solvation ability to sodium ions and improve the degree of ion dissociation. Particularly preferred are dimethoxymethane, diethoxymethane, and ethoxymethoxymethane because they have low viscosity and provide high ionic conductivity.

[0462] Examples of nitrogen-containing compounds include nitriles, fluorinated nitriles, carboxylic acid amides, fluorinated carboxylic acid amides, sulfonic acid amides and fluorinated sulfonic acid amides, acetamides, and formamides. Additionally, 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxaziridinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide can also be used. However, nitrile compounds represented by the above general formulas (1a), (1b), and (1c) are not included in the list of nitrogen-containing compounds.

[0463] Examples of the boron-containing compounds mentioned above include borate esters such as trimethylborate and triethylborate, borate ethers, and alkyl borates.

[0464] Examples of the organosilicon-containing compounds mentioned above include (CH3)4-Si, (CH3)3-Si-Si(CH3)3, and silicone oil.

[0465] Examples of the above-mentioned flame retardants include phosphate esters and phosphazene compounds. Examples of the above-mentioned phosphate esters include fluorine-containing alkyl phosphate esters, non-fluorine alkyl phosphate esters, and aryl phosphate esters. Among these, fluorine-containing alkyl phosphate esters are preferred because they can exhibit flame retardant effects even in small amounts.

[0466] Examples of the phosphazene compounds mentioned above include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0467] Examples of the above-mentioned fluorine-containing alkyl phosphate esters include, specifically, the fluorine-containing dialkyl phosphate ester described in Japanese Patent Publication No. 11-233141, the cyclic alkyl phosphate ester described in Japanese Patent Publication No. 11-283669, or the fluorine-containing trialkyl phosphate ester.

[0468] Preferred non-combustible (flame retardant) agents include (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, and (HCF2CF2CH2)3P=O.

[0469] The above-mentioned surfactant may be a cationic surfactant, anionic surfactant, nonionic surfactant, or amphoteric surfactant, but it is preferable that it contains a fluorine atom in order to obtain good cycle characteristics and rate characteristics.

[0470] Examples of surfactants containing such fluorine atoms include the following formula (30): Rf 5 COO - M + (30) (In the formula, Rf 5 M is a fluorine-containing alkyl group that may contain ether bonds with 3 to 10 carbon atoms; + is Li + kaNa + , K + Or NHR'3 + (R' may be the same or different, and both are either hydrogen or an alkyl group with 1 to 3 carbon atoms.) Fluorine-containing carboxylates represented by the following formula (40): Rf 6 SO3 - M + (40) (In the formula, Rf 6 M is a fluorine-containing alkyl group that may contain ether bonds with 3 to 10 carbon atoms; + is Li + kaNa + , K + Or NHR'3 +(R' may be the same or different, and both are either hydrogen or an alkyl group with 1 to 3 carbon atoms.) A fluorine-containing sulfonate represented by [formula] is preferred.

[0471] The amount of the surfactant described above is preferably 0.01 to 2% by mass in the electrolyte, since this can reduce the surface tension of the electrolyte without degrading the charge-discharge cycle characteristics.

[0472] Examples of the above-mentioned high dielectric additives include sulfolane, methylsulfolane, γ-butyrolactone, and γ-valerolactone.

[0473] Examples of the cycle characteristic and rate characteristic improving agents mentioned above include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0474] Furthermore, the electrolyte of this disclosure may be further combined with a polymer material to form a gel-like (plasticized) gel electrolyte.

[0475] Examples of such polymer materials include conventionally known polyethylene oxide and polypropylene oxide, and modified versions thereof (Japanese Patent Publication No. 8-222270, Japanese Patent Publication No. 2002-100405); polyacrylate polymers, polyacrylonitrile, and fluororesins such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer (Japanese Patent Publication No. 4-506726, Japanese Patent Publication No. 8-507407, Japanese Patent Publication No. 10-294131); and composites of these fluororesins and hydrocarbon resins (Japanese Patent Publication No. 11-35765, Japanese Patent Publication No. 11-86630). In particular, it is desirable to use polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymer as polymer materials for gel electrolytes.

[0476] In addition, the electrolyte of this disclosure may also include ion-conducting compounds as described in Japanese Patent Application No. 2004-301934.

[0477] This ionic conductive compound is given by formula (101): A-(D)-B (101) [In the formula, D is from formula (201): -(D1) n -(FAE) m -(AE) p -(Y) q - (201) (In the formula, D1 is given by formula (2a):

[0478] [ka]

[0479] (wherein Rf is a fluorine-containing ether group which may have a crosslinkable functional group; R 10 (This refers to a group or bond that connects Rf to the main chain.) An ether unit having a fluorine-containing ether group in its side chain; FAE is given by equation (2b):

[0480] [ka]

[0481] (wherein Rfa is a hydrogen atom, and R is a fluorinated alkyl group which may have a crosslinkable functional group; R 11 (This refers to the group or bond that connects Rfa to the main chain.) An ether unit having a fluorinated alkyl group in its side chain; AE is given by equation (2c):

[0482] [ka]

[0483] (In the formula, R 13 R is a hydrogen atom, an alkyl group which may have a crosslinkable functional group, an aliphatic cyclic hydrocarbon group which may have a crosslinkable functional group, or an aromatic hydrocarbon group which may have a crosslinkable functional group; 12 is R 13 (A group or bond that connects to the main chain) The ether unit shown by; Y is given by equations (2d-1)~(2d-3):

[0484] [ka]

[0485] A unit containing at least one of the following; n is an integer from 0 to 200; m is an integer from 0 to 200; p is an integer from 0 to 10000; q is an integer from 1 to 100; however, n+m is not 0, and the order of combination of D1, FAE, AE, and Y is not specified. A and B are the same or different, and may contain a hydrogen atom, a fluorine atom and / or a crosslinkable functional group, an alkyl group, a phenyl group, a -COOH group, -OR (where R is a hydrogen atom or a fluorine atom and / or a crosslinkable functional group), an ester group, or a carbonate group (however, if the terminal of D is an oxygen atom, it is not a -COOH group, -OR, an ester group, or a carbonate group). This is an amorphous fluorine-containing polyether compound having a fluorine-containing group in its side chain, represented by [the formula shown].

[0486] The electrolyte of this disclosure may contain a sulfone compound. Preferred sulfone compounds are cyclic sulfones having 3 to 6 carbon atoms and chain sulfones having 2 to 6 carbon atoms. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0487] Examples of cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. Among these, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred from the viewpoint of dielectric constant and viscosity, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0488] As sulfolanes, sulfolanes and / or sulfolane derivatives (hereinafter, sulfolanes may also be abbreviated as "sulfolanes") are preferred. As sulfolane derivatives, those in which one or more hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with fluorine atoms or alkyl groups are preferred.

[0489] Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methylsulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 3-sulfolene, 5-fluoro-3-(trifluoromethyl)sulfolane, etc. are preferred because they have high ionic conductivity and high input / output.

[0490] In addition, chain-like sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, and perfluoroethyl methyl sulfone. Examples include ethyltrifluoroethyl sulfone, ethylpentafluoroethyl sulfone, di(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethylisopropyl sulfone, difluoromethylisopropyl sulfone, trifluoromethylisopropyl sulfone, trifluoroethyl-n-propyl sulfone, trifluoroethylisopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethylisopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, and pentafluoroethyl-t-butyl sulfone.

[0491] Among these, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethylisopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, and trifluoromethyl-t-butyl sulfone are preferred because they have high ionic conductivity and high input / output capabilities.

[0492] The content of the sulfone compound is not particularly limited and is arbitrary as long as it does not significantly impair the effects of this disclosure, but is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and usually 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less, in 100% by volume of the solvent. If the content of the sulfone compound is within the above range, it is easy to obtain effects that improve durability such as cycle characteristics and storage characteristics, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range, a decrease in electrical conductivity can be avoided, and the input / output characteristics and charge / discharge rate characteristics of the non-aqueous electrolyte secondary battery can be set to an appropriate range.

[0493] From the viewpoint of improving output characteristics, the electrolyte of this disclosure may also preferably contain, as an additive, at least one compound (7) selected from the group consisting of lithium fluorophosphate salts (excluding LiPF6) and lithium salts having an S=O group. Furthermore, when compound (7) is used as an additive, it is preferable to use a compound other than compound (7) as the electrolyte salt mentioned above.

[0494] Examples of lithium fluorophosphate salts include lithium monofluorophosphate (LiPO3F) and lithium difluorophosphate (LiPO2F2). Examples of lithium salts having the above-mentioned S=O group include lithium monofluorosulfonate (FSO3Li), lithium methyl sulfate (CH3OSO3Li), lithium ethyl sulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethyl sulfate. Among the compounds (7), LiPO2F2, FSO3Li, and C2H5OSO3Li are preferred.

[0495] The content of compound (7) is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, even more preferably 0.1 to 10% by mass, and particularly preferably 0.1 to 7% by mass, relative to the electrolyte.

[0496] The electrolyte of this disclosure may contain other additives as needed. Examples of other additives include metal oxides and glass.

[0497] The electrolyte of this disclosure preferably contains 1 to 1000 ppm of hydrogen fluoride (HF). The inclusion of HF promotes the film formation of the additives mentioned above. If the HF content is too low, the film formation ability on the negative electrode decreases, and the characteristics of the electrochemical device tend to deteriorate. Conversely, if the HF content is too high, the oxidation resistance of the electrolyte tends to decrease due to the influence of HF. The electrolyte of this disclosure does not reduce the high-temperature storage recovery capacity rate of the electrochemical device even when containing HF within the above range. The HF content is more preferably 5 ppm or more, even more preferably 10 ppm or more, and particularly preferably 20 ppm or more. The HF content is also more preferably 200 ppm or less, even more preferably 100 ppm or less, even more preferably 80 ppm or less, and particularly preferably 50 ppm or less. The HF content can be measured by neutralization titration.

[0498] The electrolyte of this disclosure may be prepared by any method using the components described above.

[0499] The electrolyte of this disclosure is used in sodium-ion secondary batteries. In this specification, a sodium-ion secondary battery means a secondary battery that uses at least sodium ions as carriers. Therefore, secondary batteries that use sodium ions in combination with other ions (e.g., potassium ions) as carriers are also included. A sodium-ion secondary battery typically comprises a positive electrode and a negative electrode capable of intercepting and releasing sodium ions (and other ions as needed), and an electrolyte.

[0500] This disclosure also relates to a sodium-ion secondary battery comprising the electrolyte of this disclosure. The sodium-ion secondary battery of this disclosure preferably comprises a positive electrode, a negative electrode, and the electrolyte of this disclosure as described above.

[0501] <Positive electrode> The positive electrode consists of a positive electrode active material layer containing positive electrode active material and a current collector.

[0502] The positive electrode active material is not particularly limited as long as it is capable of electrochemically intercalating and releasing sodium ions, but examples include sodium-containing transition metal composite oxides, sodium-containing transition metal phosphate compounds, sulfur-based materials, and conductive polymers. Among these, sodium-containing transition metal composite oxides and sodium-containing transition metal phosphate compounds are preferred as positive electrode active materials, and sodium-containing transition metal composite oxides that produce high voltage are particularly preferred.

[0503] Preferred transition metals for sodium-containing transition metal composite oxides include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include sodium-cobalt composite oxides such as NaCoO2, sodium-nickel composite oxides such as NaNiO2, sodium-manganese composite oxides such as NaMnO2, NaMn2O4, and Na2MnO4, and those in which some of the main transition metal atoms in these sodium transition metal composite oxides are substituted with other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. A specific example of a substituted element is, for example, NaNi 2 / 9 Cu 1 / 9 Fe 1 / 3 Mn 1 / 3 O2, NaNi 0.5 Mn 0.5 O2, NaNi 0.85 Co 0.10 Al 0.05 O2, NaNi 0.5 Co 0.2 Mn 0.3 O2, NaNi 0.6 Co 0.2 Mn 0.2 O2, NaNi 0.33 Co 0.33 Mn 0.33 O2, NaNi 0.8 Co 0.1 Mn 0.1 O2, NaNi 0.45 Co 0.10 Al 0.45 O2, NaMn 1.8 Al 0.2 O4, NaMn 1.5 Ni 0.5 Examples include O4.

[0504] Among the sodium-containing transition metal composite oxides mentioned above, NaMn has a high energy density even at high voltages. 1.5 Ni 0.5 O4, NaNi 0.5 Co 0.2 Mn 0.3 O2, NaNi 0.6 Co 0.2 Mn 0.2O2 is preferred. In particular, NaMn is preferred for high voltages of 4.3V or higher. 1.5 Ni 0.5 O4 is preferred.

[0505] Furthermore, among the sodium-containing transition metal composite oxides mentioned above, NaNi is particularly suitable because it can provide high-capacity sodium-ion secondary batteries. 0.6 Co 0.2 Mn 0.2 O2, NaNi 0.8 Co 0.1 Mn 0.1 O2, NaNi 0.85 Co 0.10 Al 0.05 O2 is preferred.

[0506] Preferred transition metals for sodium-containing transition metal phosphate compounds include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include iron phosphates such as NaFePO4, Na3Fe2(PO4)3, and NaFeP2O7, cobalt phosphates such as NaCoPO4, and those in which some of the transition metal atoms that make up the main component of these sodium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.

[0507] Examples of the sodium-containing transition metal composite oxides mentioned above include: Formula: Na a Mn 2-b M 1 b O4 (in the formula, 0.9≦a;0≦b≦1.5;M 1 (This refers to a sodium-manganese spinel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Ni, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge.) Formula: NaNi 1-c M 2 c O2 (where 0≦c≦0.5;M 2(This refers to a sodium-nickel composite oxide represented by at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), or Formula:NaCo 1-d M 3 d O2 (where 0≦d≦0.5;M 3 Examples include sodium-cobalt composite oxides represented by at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge.

[0508] In particular, NaNi is a highly energy-dense, high-output sodium-ion secondary battery that can provide such power. 2 / 9 Cu 1 / 9 Fe 1 / 3 Mn 1 / 3 O2, NaCoO2, NaMnO2, NaNiO2, NaMn2O4, NaNi 0.8 Co 0.15 Al 0.05 O2, or NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 is preferred.

[0509] Other positive electrode active materials include NaFePO4 and NaNi 0.8 Co 0.2 O2, Na 1.2 Fe 0.4 Mn 0.4 O2, NaNi 0.5 Mn 0.5 Examples include O2, NaV3O6, and Na2MnO3.

[0510] Examples of the sulfur-based material include materials containing sulfur atoms, and preferably at least one selected from the group consisting of elemental sulfur, metal sulfides, and organic sulfur compounds, with elemental sulfur being more preferred. The metal sulfide may be a metal polysulfide. The organic sulfur compound may be an organic polysulfide.

[0511] The above metal sulfide is NaSx A compound represented by (0 < x ≤ 8); Na2S x A compound represented by (0 < x ≤ 8); A compound having a two-dimensional layered structure such as TiS2 and MoS2; General formula Me x Examples include Schubler compounds having a strong three-dimensional skeletal structure represented by Mo6S8 (Me is various transition metals including Pb, Ag, and Cu).

[0512] Examples of the above organic sulfur compound include carbon sulfide compounds and the like.

[0513] The above organic sulfur compound may be supported on a material having pores such as carbon and used as a carbon composite material. As the sulfur content in the carbon composite material, since the cycle performance is further improved and the overvoltage is further reduced, for the above carbon composite material, 10 to 99% by mass is preferable, 20% by mass or more is more preferable, 30% by mass or more is further preferable, 40% by mass or more is particularly preferable, and 85% by mass or less is preferable. When the above positive electrode active material is the above sulfur simple substance, the sulfur content contained in the above positive electrode active material is equal to the content of the above sulfur simple substance.

[0514] Examples of the conductive polymer include p-doped type conductive polymers and n-doped type conductive polymers. Examples of the conductive polymer include polyacetylene-based, polyphenylene-based, heterocyclic polymers, ionic polymers, ladder and network polymers, and the like.

[0515] In addition, it is preferable to include sodium phosphate in the positive electrode active material because the continuous charging characteristics are improved. There is no limitation on the use of sodium phosphate, but it is preferable to mix and use the above positive electrode active material and sodium phosphate. The amount of sodium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and further preferably 0.5% by mass or more with respect to the total of the above positive electrode active material and sodium phosphate, and the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less.

[0516] Furthermore, a positive electrode active material may be used in which a substance of a different composition is attached to its surface. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0517] These surface-adhering substances can be attached to the surface of the positive electrode active material by, for example, dissolving or suspending them in a solvent and impregnating them into the positive electrode active material, followed by drying; dissolving or suspending a surface-adhering substance precursor in a solvent and impregnating it into the positive electrode active material, then reacting it by heating, etc.; or adding it to the positive electrode active material precursor and simultaneously firing it. In addition, when attaching carbon, a method of mechanically attaching carbonaceous material afterwards, for example in the form of activated carbon, can also be used.

[0518] The amount of surface-adhered material is preferably 0.1 ppm or more, more preferably 1 ppm or more, and even more preferably 10 ppm or more, relative to the positive electrode active material by mass, with an upper limit of preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. The surface-adhered material can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material, thereby improving battery life. However, if the amount of adhesion is too small, the effect will not be fully realized, and if it is too large, it may inhibit the movement of sodium ions, which may increase resistance.

[0519] The particle shapes of the positive electrode active material can include conventionally used shapes such as lumpy, polyhedral, spherical, ellipsoidal, plate-like, needle-like, and columnar. Furthermore, primary particles may aggregate to form secondary particles.

[0520] The tap density of the positive electrode active material is typically 1.5 g / cm³. 3 Preferably 2.0 g / cm³ 3 More preferably 2.5 g / cm³3 In summary, the most preferred amount is 3.0 g / cm³. 3 The above is a summary. If the tap density of the positive electrode active material falls below the above lower limit, the amount of dispersion medium required during the formation of the positive electrode active material layer increases, as does the amount of conductive material and binder needed, which may restrict the filling rate of the positive electrode active material into the positive electrode active material layer and thus limit the battery capacity. By using metal composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, a higher tap density is preferable, and there is no particular upper limit, but it is usually 4.5 g / cm³. 3 Preferably, 4.3 g / cm³ 3 The following applies: In this disclosure, the tap density is defined as the powder packing density (tap density) g / cm³ obtained when 5-10 g of positive electrode active material powder is placed in a 10 ml glass graduated cylinder and tapped 200 times with a stroke of approximately 20 mm. 3 We will seek it as follows.

[0521] The median diameter d50 of the positive electrode active material particles (or secondary particle diameter if primary particles aggregate to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, even more preferably 0.8 μm or more, and most preferably 1.0 μm or more. It is also preferably 30 μm or less, more preferably 27 μm or less, even more preferably 25 μm or less, and most preferably 22 μm or less. If it falls below the lower limit, it may not be possible to obtain a high tap density product, and if it exceeds the upper limit, the diffusion of lithium within the particles will take longer, which may lead to a decrease in battery performance or cause problems such as streaking when creating the positive electrode of the battery, i.e., when slurrying the active material with conductive material and binder in a solvent and coating it into a thin film. Here, by mixing two or more of the above positive electrode active materials having different median diameters d50, the packing performance during positive electrode creation can be further improved.

[0522] In this disclosure, the median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using the HORIBA LA-920 as the particle size distribution analyzer, a 0.1% by mass aqueous solution of sodium hexametaphosphate is used as the dispersion medium during measurement, and the measurement is performed after ultrasonic dispersion for 5 minutes with the measurement refractive index set to 1.24.

[0523] When primary particles aggregate to form secondary particles, the average primary particle diameter of the positive electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, and most preferably 2 μm or less. Exceeding the upper limit makes it difficult to form spherical secondary particles, which can adversely affect powder packing properties and significantly reduce the specific surface area, potentially leading to a decrease in battery performance such as output characteristics. Conversely, below the lower limit usually results in problems such as poor reversibility of charge and discharge due to underdeveloped crystals.

[0524] In this disclosure, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, it is determined by taking a photograph at 10,000x magnification, finding the longest value of the intercept between the left and right boundaries of the primary particle relative to a horizontal line for any 50 primary particles, and taking the average value.

[0525] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m². 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 The value is 1 / g or more, and the upper limit is preferably 50m 2 / g or less, more preferably 40m 2 / g or less, more preferably 30m 2 It is less than / g. If the BET specific surface area is smaller than this range, battery performance tends to decrease, and if it is larger, it becomes difficult to increase the tap density, which can cause problems with coating when forming the positive electrode active material layer.

[0526] In this disclosure, the BET specific surface area is defined as the value measured by a nitrogen adsorption BET single-point method using a gas flow method, after pre-drying the sample at 150°C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.), and then using a nitrogen-helium mixed gas that has been precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3.

[0527] When the sodium-ion secondary battery of this disclosure is used as a large-scale sodium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required, so it is preferable that the particles of the positive electrode active material consist mainly of secondary particles. The positive electrode active material particles preferably contain 0.5 to 7.0 volume percent of fine particles with an average secondary particle diameter of 40 μm or less and an average primary particle diameter of 1 μm or less. By including fine particles with an average primary particle diameter of 1 μm or less, the contact area with the electrolyte is increased, allowing for faster diffusion of sodium ions between the electrode and the electrolyte, and as a result, the output performance of the battery can be improved.

[0528] For the production of positive electrode active materials, general methods for producing inorganic compounds are used. In particular, various methods can be considered for producing spherical or ellipsoidal active materials. For example, a method can be used in which transition metal raw materials are dissolved or pulverized and dispersed in a solvent such as water, the pH is adjusted while stirring to create and recover spherical precursors, these are dried as needed, and then an active material is obtained by adding a Na source such as NaOH, Na2CO3, or NaNO3 and calcining at a high temperature.

[0529] For the manufacture of the positive electrode, the positive electrode active material may be used alone, or two or more materials with different compositions may be used in any combination or ratio. In this case, a preferred combination is NaCoO2 and NaNi 0.33 Co 0.33 Mn 0.33Examples include combinations of NaMn2O4 such as O2, or in which part of the Mn is substituted with other transition metals, or combinations of NaCoO2, or in which part of the Co is substituted with other transition metals.

[0530] The content of the positive electrode active material described above is preferably 50 to 99.5% by mass of the positive electrode mixture, and more preferably 80 to 99% by mass, in order to achieve high battery capacity. Furthermore, the content of the positive electrode active material 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, and more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is too low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0531] The above positive electrode mixture preferably further includes a binder, a thickener, and a conductive material. As the binder mentioned above, any material can be used as long as it is safe for the solvent and electrolyte used during electrode manufacturing. Examples include: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, and nitrocellulose; rubbery polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; styrene-butadiene-styrene block copolymer or its hydrogenated additives; and EPDM (ethylene methyl phosphate). Examples include thermoplastic elastomer polymers such as ethylene-propylene-diene terpolymer, styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, or hydrogenated versions thereof; soft resin-like polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymer, and tetrafluoroethylene-ethylene copolymer; and polymer compositions having ionic conductivity for alkali metal ions (especially sodium ions). These may be used individually or in any combination and ratio of two or more types.

[0532] The binder content, as a percentage of the positive electrode active material layer, is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.2% by mass or more, and usually 40% by mass or less, preferably 30% by mass or less, more preferably 20% by mass or less, and most preferably 10% by mass or less. If the binder content is too low, the positive electrode active material cannot be sufficiently held, resulting in insufficient mechanical strength of the positive electrode and deterioration of battery performance such as cycle characteristics. On the other hand, if it is too high, it may lead to a decrease in battery capacity and conductivity.

[0533] Examples of the thickening agents mentioned above include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, starch oxide, phosphated starch, casein, polyvinylpyrrolidone, and salts thereof. One of these may be used alone, or two or more may be used in any combination and ratio.

[0534] The ratio of the thickener to the active material is usually 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, and usually within the range of 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If it is below this range, the coating properties may be significantly reduced. If it is above this range, the proportion of active material in the positive electrode active material layer will decrease, which may lead to problems such as a decrease in battery capacity or an increase in resistance between positive electrode active materials.

[0535] Any known conductive material can be used as the conductive material. Specific examples include metal materials such as copper, nickel, and gold; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon materials such as needle coke, carbon nanotubes, fullerene, and amorphous carbon such as VGCF. These may be used individually or in any combination and ratio of two or more materials. The conductive material is usually contained in the positive electrode active material layer in an amount of 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less, and more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

[0536] The solvent used to form the slurry is not particularly limited in type, as long as it is capable of dissolving or dispersing the positive electrode active material, conductive material, binder, and thickener used as needed. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and a mixture of alcohol and water. Examples of organic solvents include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide.

[0537] Suitable materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or their alloys; and carbon materials such as carbon cloth and carbon paper. Among these, metal materials, particularly aluminum or its alloys, are preferred.

[0538] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal for metal materials, and carbon plates, carbon thin films, and carbon cylinders for carbon materials. Of these, metal thin films are preferred. The thin film may be formed in a mesh shape as appropriate. The thickness of the thin film is arbitrary, but is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, and more preferably 50 μm or less. If the thin film is thinner than this range, it may lack the necessary strength as a current collector. Conversely, if the thin film is thicker than this range, its handling may be impaired.

[0539] Furthermore, it is preferable that a conductive additive is applied to the surface of the current collector, as this reduces the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of conductive additives include carbon and precious metals such as gold, platinum, and silver.

[0540] The ratio of the thickness of the current collector to the thickness of the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is preferably 20 or less, more preferably 15 or less, most preferably 10 or less, and also preferably 0.5 or more, more preferably 0.8 or more, most preferably 1 or more. If it exceeds this range, the current collector may generate heat due to Joule heating during high current density charging and discharging. If it falls below this range, the volume ratio of the current collector to the positive electrode active material increases, which may reduce the battery capacity.

[0541] The positive electrode can be manufactured by conventional methods. For example, the positive electrode active material can be mixed with the aforementioned binder, thickener, conductive material, solvent, etc., to form a slurry-like positive electrode mixture, which can then be applied to a current collector, dried, and pressed to increase its density.

[0542] The above-mentioned densification can be achieved by hand pressing, roller pressing, etc. The density of the positive electrode active material layer is preferably 1.0 g / cm³ or more, more preferably 1.3 g / cm³ or more, even more preferably 1.5 g / cm³ or more, and also preferably in the range of 5 g / cm³ or less, more preferably 3.0 g / cm³ or less, and even more preferably 2.5 g / cm³ or less. If it exceeds this range, the permeability of the electrolyte to the vicinity of the current collector / active material interface decreases, and the charge / discharge characteristics, especially at high current densities, deteriorate, and high output may not be obtained. If it falls below this range, the conductivity between the active materials decreases, the battery resistance increases, and high output may not be obtained.

[0543] When using the electrolyte of this disclosure, from the viewpoint of increasing high power output and stability at high temperatures, it is preferable that the area of ​​the positive electrode active material layer be large relative to the outer surface area of ​​the battery casing. Specifically, it is preferable that the sum of the electrode areas of the positive electrode be 15 times or more in area ratio to the surface area of ​​the secondary battery casing, and more preferably 40 times or more. The outer surface area of ​​the battery casing refers to the total area calculated from the length, width, and thickness of the case portion filled with the power generation elements, excluding the terminal protrusions, in the case of a bottomed rectangular shape. In the case of a bottomed cylindrical shape, it is the geometric surface area approximating the case portion filled with the power generation elements, excluding the terminal protrusions, as a cylinder. The sum of the electrode areas of the positive electrode refers to the geometric surface area of ​​the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in a structure in which positive electrode mixture layers are formed on both sides via a current collector foil, it refers to the sum of the areas calculated separately for each surface.

[0544] The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer, after subtracting the thickness of the metal foil of the core material, is preferably 10 μm or more, more preferably 20 μm or more, and preferably 500 μm or less, and more preferably 450 μm or less, as a lower limit for one side of the current collector.

[0545] Furthermore, a positive electrode plate with a substance of a different composition attached to its surface may also be used. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon.

[0546] <Negative electrode> The negative electrode consists of a negative electrode active material layer containing the negative electrode active material and a current collector.

[0547] The negative electrode active material is not particularly limited as long as it is capable of electrochemically intercepting and releasing sodium ions. Specific examples include carbon materials, alloy materials, sodium-containing metal composite oxide materials, and conductive polymers. These may be used individually or in any combination of two or more materials.

[0548] Examples of the above-mentioned negative electrode active materials include carbonaceous materials capable of adsorbing and releasing sodium, such as thermal decomposition products of organic materials under various thermal decomposition conditions, artificial graphite, natural graphite, and hard carbon; metal oxide materials capable of adsorbing and releasing sodium, such as tin oxide and silicon oxide; sodium metal; various sodium alloys; and sodium-containing metal composite oxide materials. Two or more of these negative electrode active materials may be used in combination.

[0549] Preferably, the carbonaceous material capable of adsorbing and releasing sodium is hard carbon, artificial graphite or refined natural graphite produced by high-temperature treatment of easily graphitizable pitch obtained from various raw materials, or graphite obtained by surface-treating these graphites with pitch or other organic materials and then carbonizing them. More preferably, a material selected from natural graphite, artificial graphite, artificial carbonaceous material, and a carbonaceous material obtained by heat-treating an artificial graphitic material once or more times in the range of 400 to 3200°C, a carbonaceous material in which the negative electrode active material layer consists of at least two types of carbonaceous materials with different crystalline properties and / or has an interface where these different crystalline carbonaceous materials are in contact, or a carbonaceous material in which the negative electrode active material layer has an interface where at least two types of carbonaceous materials with different orientations are in contact, is selected because it provides a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Furthermore, these carbon materials may be used individually, or two or more types may be used in any combination and ratio.

[0550] Carbonaceous materials obtained by heat-treating the above-mentioned artificial carbonaceous materials and artificial graphite materials once or more in the range of 400 to 3200°C include coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch and pitches that have been oxidized, needle coke, pitch coke and carbon agents that have been partially graphitized therein, thermal decomposition products of organic materials such as furnace black, acetylene black, and pitch-based carbon fibers, carbonizable organic materials and their carbonized products, or solutions obtained by dissolving carbonizable organic materials in low molecular weight organic solvents such as benzene, toluene, xylene, quinoline, and n-hexane, and their carbonized products.

[0551] The metallic material used as the negative electrode active material (excluding sodium-titanium composite oxide) is not particularly limited, as long as it can absorb and release sodium, and may be elemental sodium, elemental metals and alloys that form sodium alloys, or compounds such as oxides, carbides, nitrides, silicides, sulfides, or phosphides thereof. The elemental metals and alloys that form sodium alloys are preferably materials containing metals and metalloid elements of Groups 13 and 14, and more preferably elemental metals of aluminum, silicon, and tin (hereinafter abbreviated as "specific metallic elements") and alloys or compounds containing these atoms. These may be used individually or in any combination and ratio of two or more.

[0552] Examples of negative electrode active materials having at least one atom selected from specific metal elements include elemental metals of any one of the specific metal elements, alloys composed of two or more specific metal elements, alloys composed of one or more specific metal elements and one or more other metal elements, compounds containing one or more specific metal elements, and composite compounds such as oxides, carbides, nitrides, silicides, sulfides, or phosphides of such compounds. By using these elemental metals, alloys, or metal compounds as negative electrode active materials, it is possible to increase the capacity of the battery.

[0553] In addition, these composite compounds also include compounds in which several elements such as simple metals, alloys or non-metallic elements are complexly bonded. Specifically, for example, in the case of silicon or tin, alloys of these elements and metals that do not act as negative electrodes can be used. For example, in the case of tin, complex compounds containing 5 to 6 elements in combination with a metal that acts as a negative electrode other than silicon and tin, a metal that does not operate as a negative electrode, and a non-metallic element can also be used.

[0554] Specifically, simple Si, SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu6Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiO v (0 < v ≤ 2), NaSiO or simple tin, SnSiO3, NaSnO, Mg2Sn, SnO w (0 < w ≤ 2) can be mentioned. In addition, composite materials containing Si or Sn as the first constituent element and, in addition, second and third constituent elements can be mentioned. The second constituent element is, for example, at least one of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium and zirconium. The third constituent element is, for example, at least one of boron, carbon, aluminum and phosphorus. In particular, since high battery capacity and excellent battery characteristics can be obtained, as the above metal material, simple silicon or tin (which may contain trace amounts of impurities), SiO v (0 < v ≤ 2), SnO w (0 ≤ w ≤ 2), Si-Co-C composite material, Si-Ni-C composite material, Sn-Co-C composite material, Sn-Ni-C composite material are preferred.

[0555] The sodium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can absorb and release sodium, but from the viewpoint of high current density charge / discharge characteristics, materials containing titanium and lithium are preferred, more preferably sodium-containing composite metal oxide materials containing titanium, and even more preferably sodium-titanium composite oxides (hereinafter abbreviated as "sodium-titanium composite oxide"). In other words, using a sodium-titanium composite oxide having a spinel structure as the negative electrode active material for an electrolyte battery is particularly preferred because it greatly reduces the output resistance.

[0556] The above sodium titanium composite oxide has the general formula: Na x Ti y M z O4 [In the formula, M represents at least one element selected from the group consisting of K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb.] It is preferable that the compound is represented by [formula]. Among the above compositions, (i)1.2≦x≦1.4, 1.5≦y≦1.7, z=0 (ii)0.9≦x≦1.1, 1.9≦y≦2.1, z=0 (iii)0.7≦x≦0.9, 2.1≦y≦2.3, z=0 This structure is particularly preferable because it offers a good balance of battery performance.

[0557] A particularly preferred representative composition of the above compound is (i) Na 4 / 3 Ti 5 / 3 O4, (ii) Na1Ti2O4, (iii) Na 4 / 5 Ti 11 / 5 It is O4. Also, for structures where Z≠0, for example, Na 4 / 3 Ti 4 / 3 Al 1 / 3 O4 is a preferred choice.

[0558] The above-mentioned negative electrode mixture preferably further includes a binder, a thickener, and a conductive material.

[0559] Examples of the binders mentioned above include those similar to the binders that can be used for the positive electrode as described above. The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 8% by mass or less. If the ratio of the binder to the negative electrode active material exceeds the above range, the proportion of binder that does not contribute to the battery capacity increases, which may lead to a decrease in battery capacity. Also, if it falls below the above range, it may lead to a decrease in the strength of the negative electrode.

[0560] In particular, when a rubbery polymer such as SBR is included as the main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. Furthermore, when a fluorine-based polymer such as polyvinylidene fluoride is included as the main component, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

[0561] Examples of the thickening agents mentioned above include those similar to the thickening agents that can be used in the positive electrode as described above. The ratio of the thickening agent to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. If the ratio of the thickening agent to the negative electrode active material falls below the above range, the coating properties may be significantly reduced. If it exceeds the above range, the proportion of negative electrode active material in the negative electrode active material layer decreases, which may lead to problems such as a decrease in battery capacity or an increase in resistance between negative electrode active materials.

[0562] Examples of conductive materials for the negative electrode include metallic materials such as copper and nickel, and carbon materials such as graphite and carbon black.

[0563] The solvent used to form the slurry is not particularly limited in type, as long as it is capable of dissolving or dispersing the negative electrode active material, binder, and, if necessary, the thickener and conductive material. Either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and alcohol, while examples of organic solvents include N-methylpyrrolidone (NMP), N-butylpyrrolidone (NBP), 3-methoxy-N,N-dimethylpropionamide, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N,N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphoramide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, and hexane.

[0564] Suitable materials for the negative electrode current collector include aluminum, copper, nickel, and stainless steel. Among these, aluminum foil is preferred due to its ease of processing into a thin film and its cost-effectiveness.

[0565] The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and usually 100 μm or less, preferably 50 μm or less. If the thickness of the negative electrode current collector is too thick, the overall capacity of the battery may decrease too much, and conversely, if it is too thin, it may become difficult to handle.

[0566] The negative electrode can be manufactured by conventional methods. For example, one method involves adding the aforementioned binder, thickener, conductive material, solvent, etc., to the negative electrode material to form a slurry, applying it to a current collector, drying it, and then pressing it to increase its density. When using alloy materials, methods such as vapor deposition, sputtering, or plating can be used to form a thin film layer (negative electrode active material layer) containing the aforementioned negative electrode active material.

[0567] The electrode structure when the negative electrode active material is used as an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is 1 g·cm³.-3 The above is preferable, 1.2 g·cm -3 The above is even more preferable: 1.3 g·cm -3 The above is particularly preferable, and also 2.2 g·cm -3 The following is preferable: 2.1 g·cm -3 The following is more preferable: 2.0 g·cm -3 The following is even more preferable: 1.9 g·cm -3 The following are particularly preferable. If the density of the negative electrode active material present on the current collector exceeds the above range, the negative electrode active material particles may be destroyed, leading to an increase in the initial irreversible capacity and a deterioration of high-current-density charge-discharge characteristics due to reduced electrolyte permeability near the current collector / negative electrode active material interface. Conversely, if it falls below the above range, the conductivity between the negative electrode active materials decreases, increasing the battery resistance and potentially reducing the capacity per unit volume.

[0568] The thickness of the negative electrode plate is designed to match the positive electrode plate used and is not particularly limited, however, the thickness of the composite layer after subtracting the thickness of the core metal foil is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

[0569] Furthermore, a negative electrode plate with a substance of a different composition attached to its surface may also be used. Examples of surface-attached substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; and carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.

[0570] <Separator> The sodium-ion secondary battery of this disclosure preferably further comprises a separator. The material and shape of the separator described above are not particularly limited as long as they are stable in the electrolyte and have excellent liquid retention properties, and known materials can be used. In particular, it is preferable to use a porous sheet or nonwoven fabric in the form of a material that is stable in the electrolyte of this disclosure, such as a resin, glass fiber, or inorganic material, and has excellent liquid retention properties.

[0571] As materials for the resin and glass fiber separator, for example, polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters can be used. These materials, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films, may be used individually or in any combination and ratio of two or more. In particular, the separator is preferably a porous sheet or nonwoven fabric made from polyolefins such as polyethylene and polypropylene, as it has good electrolyte permeability and shut-off effect.

[0572] The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, and more preferably 30 μm or less. If the separator is too thin compared to the above range, the insulating properties and mechanical strength may decrease. If it is too thick compared to the above range, not only may the battery performance such as rate characteristics decrease, but the energy density of the electrolyte battery as a whole may decrease.

[0573] Furthermore, when using porous materials such as porous sheets or nonwoven fabrics as separators, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, and usually 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too small compared to the above range, the film resistance tends to increase and the rate characteristics tend to deteriorate. Also, if it is too large compared to the above range, the mechanical strength of the separator tends to decrease and the insulating properties tend to deteriorate.

[0574] Furthermore, while the average pore size of the separator is arbitrary, it is usually 0.5 μm or less, preferably 0.2 μm or less, and usually 0.05 μm or more. If the average pore size exceeds the above range, short circuits are more likely to occur. Conversely, if it falls below the above range, the film resistance increases and the rate characteristics may deteriorate.

[0575] On the other hand, inorganic materials such as oxides of alumina and silicon dioxide, nitrides of aluminum nitride and silicon nitride, and sulfates of barium sulfate and calcium sulfate are used, and these are available in particulate or fibrous form.

[0576] In terms of form, thin films such as nonwoven fabrics, woven fabrics, and microporous films are used. In the thin film form, those with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above independent thin film forms, a separator can be used in which a composite porous layer containing the above inorganic particles is formed on the surface of the positive electrode and / or negative electrode using a resin binder. For example, a porous layer can be formed on both sides of the positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0577] <Battery design> The electrode group may be either a laminated structure in which the positive electrode plate and the negative electrode plate are separated by the separator, or a structure in which the positive electrode plate and the negative electrode plate are spirally wound around the separator. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less.

[0578] If the electrode group occupancy rate falls below the above range, the battery capacity will decrease. Conversely, if it exceeds the above range, the void space is small, and the internal pressure increases due to the expansion of materials and the vapor pressure of the electrolyte liquid component as the battery heats up. This reduces various characteristics of the battery, such as its charge / discharge cycle performance and high-temperature storage capabilities, and may even cause the gas release valve that releases the internal pressure to activate.

[0579] The current collection structure is not particularly limited, but in order to more effectively achieve improved high-current-density charge-discharge characteristics with the electrolyte of this disclosure, it is preferable to have a structure that reduces the resistance of the wiring and junction parts. When the internal resistance is reduced in this way, the effects of using the electrolyte of this disclosure are particularly well exhibited.

[0580] In electrode groups with the above-described laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to a terminal is preferably used. When the area of ​​a single electrode is large, the internal resistance increases, so it is also preferable to provide multiple terminals within the electrode to reduce the resistance. In electrode groups with the above-described wound structure, the internal resistance can be lowered by providing multiple lead structures for both the positive and negative electrodes and bundling them to a terminal.

[0581] The material of the outer casing is not particularly limited as long as it is a stable material for the electrolyte used. Specifically, metals such as nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or laminated films of resin and aluminum foil can be used. From the viewpoint of weight reduction, aluminum or aluminum alloy metals or laminated films are preferably used.

[0582] Outer cases using metals may be sealed by welding the metals together using laser welding, resistance welding, or ultrasonic welding, or by using a crimped structure with the metals connected via a resin gasket. Outer cases using laminate film may be sealed by heat-fusing the resin layers together. To improve sealing performance, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when a sealed structure is formed by heat-fusing the resin layers via a current collector terminal, since it is a joint between metal and resin, a resin having polar groups or a modified resin with introduced polar groups is preferably used as the interposing resin.

[0583] The shape of the sodium-ion secondary battery in this disclosure is arbitrary and can be any shape, such as cylindrical, prismatic, laminated, coin-type, or large. The shape and configuration of the positive electrode, negative electrode, and separator can be changed and used according to the shape of each battery.

[0584] A module comprising a sodium-ion secondary battery as described herein is also part of this disclosure.

[0585] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Examples]

[0586] The present disclosure will now be explained with reference to examples, but the present disclosure is not limited to such examples.

[0587] The structure of the compound obtained in the synthesis example is 1 H or 19 It was identified by F-NMR.

[0588] Synthesis Example 1 <Synthesis of sodium diethylsulfamate (compound A)> Sodium chloride (4.1 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of diethylamine (6.2 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the target crude sodium diethylsulfamate (13.6 g). The obtained crude sodium diethylsulfamate (13 g) was dissolved in 7 mL of methanol at 60°C, and 7 mL of dimethyl carbonate was added, and the solution was concentrated under reduced pressure until the volume was halved. Another 7 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium diethylsulfamate (11.3 g, 64 mmol, total yield 83%). [ka]

[0589] Synthesis Example 2 <Synthesis of sodium pentane-1,5-diylsulfamate (compound B)> Sodium chloride (4.1 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of piperidine (7.2 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the target crude sodium pentane-1,5-diylsulfamate (8.8 g). The obtained crude sodium pentane-1,5-diylsulfamate (8.0 g) was dissolved in 16 mL of methanol at 60°C, and 16 mL of dimethyl carbonate was added, and the mixture was concentrated under reduced pressure until the volume was halved. Another 16 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium pentane-1,5-diylsulfamate (5.6 g, 30 mmol, total yield 38%). [ka]

[0590] Synthesis Example 3 <Synthesis of sodium 3-oxapentane-1,5-diylsulfamate (compound C)> Sodium chloride (4.1 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of morpholine (7.4 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the target crude 3-oxapentane-1,5-diylsulfamate sodium (13.1 g). The obtained crude 3-oxapentane-1,5-diylsulfamate sodium (13 g) was dissolved in 140 mL of methanol at 60°C, and 100 mL of dimethyl carbonate was added, and the mixture was concentrated under reduced pressure until the volume was halved. Another 100 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium 3-oxapentane-1,5-diylsulfamate (8.7 g, 46 mmol, total yield 59%). [ka]

[0591] Synthesis Example 4 <Synthesis of sodium bis(2,2,2-trifluoroethyl)sulfamate (compound D)> Sodium chloride (1.4 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and bis(2,2,2-trifluoroethyl)amine (10.3 g, 57 mmol) was added dropwise under an ice bath (reaction solution temperature rise 0-5°C, addition time approximately 5 minutes). This solution was stirred at room temperature for 1 hour, then triethylamine (6.0 g) and dichloromethane (50 mL) were added, and the mixture was stirred for a further day. The resulting reaction mixture was filtered and washed with dichloromethane to obtain the target sodium bis(2,2,2-trifluoroethyl)sulfamate (3.1 g, 11 mmol, total yield 42%). [ka]

[0592] Synthesis Example 5 <Synthesis of sodium bis(fluorosulfonyl)sulfamate (compound E)> Sodium bis(fluorosulfonyl)imide (3.9 g, 19 mmol) and diethyl ether (30 mL) were added to a reaction vessel, and chlorosulfonic acid (2.2 g, 19 mmol) was added dropwise (no exothermic reaction). After stirring this solution at room temperature for 1 day, the solvent was removed by distillation to obtain the target sodium bis(fluorosulfonyl)sulfamate (4.1 g, yield 42%). [ka]

[0593] Synthesis Example 6 <Synthesis of sodium ethyl 2,2,2-trifluoroethylsulfamate (compound F)> Sodium chloride (1.4 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and methyl 2,2,2-trifluoroethylamine (6.4 g, 57 mmol) was added dropwise under an ice bath (reaction solution temperature rise 0-5°C, addition time approximately 5 minutes). This solution was stirred at room temperature for 1 hour, then triethylamine (6.0 g) and dichloromethane (50 mL) were added, and the mixture was stirred for a further day. The resulting reaction mixture was filtered and washed with dichloromethane to obtain the target sodium methyl 2,2,2-trifluoroethylsulfamate (2.7 g, 12 mmol, total yield 46%). [ka]

[0594] Synthesis Example 7 <Synthesis of sodium dimethylsulfamate (compound G)> Sodium chloride (4.1 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of dimethylamine (5.8 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the desired crude sodium dimethylsulfamate (12.6 g). The obtained crude sodium dimethylsulfamate (12 g) was dissolved in 7 mL of methanol at 60°C, and 7 mL of dimethyl carbonate was added, and the mixture was concentrated under reduced pressure until the volume was halved. Another 7 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium dimethylsulfamate (10.3 g, 70 mmol, total yield 82%). [ka]

[0595] Synthesis Example 8 <Synthesis of sodium ethylsulfamate (compound H)> Sodium chloride (1.4 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of ethylamine (2 M THF solution, 28.5 mL, 57 mmol) and triethylamine (6.0 g, 59 mmol) was added dropwise under an ice bath (reaction solution temperature rise 0-5°C, addition time 20-30 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the desired crude sodium ethylsulfamate (3.3 g). The obtained crude sodium ethylsulfamate (3.3 g) was dissolved in 7 mL of methanol at 60°C, and 7 mL of dimethyl carbonate was added, and the solution was concentrated under reduced pressure until the volume was halved. Another 7 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium ethylsulfamate (3.0 g, 20 mmol, total yield 78%). [ka]

[0596] Synthesis Example 9 <Synthesis of sodium sulfamate (compound I)> Sodium chloride (1.4 g, 24 mmol) and dimethyl carbonate (35 mL) were added to a reaction vessel, and chlorosulfonic acid (3.0 g, 26 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and ammonia (1.0 g, 57 mmol) was added under pressure in an ice bath (reaction solution temperature rise 0-5°C, setup time approximately 30 minutes). This solution was stirred at room temperature for 1 hour, then triethylamine (6.0 g) and dichloromethane (50 mL) were added, and the mixture was stirred for a further day. The resulting reaction mixture was filtered and washed with dichloromethane to obtain the target sodium sulfamate (2.1 g, 22 mmol, total yield 84%). [ka]

[0597] Synthesis Example 10 <Synthesis of sodium difluorosulfamate (compound J)> Sulfamic acid (16.4 g, 170 mmol), water (30 ml), and sodium hydroxide (7.7 g, 180 mmol) were added to a reaction vessel, and fluorine gas was bubbled in at 0°C. After 2 hours, the solution was neutralized with an aqueous sodium hydroxide solution, and after removing the solvent, acetonitrile was added and the mixture was filtered. The filtrate was vacuum-dried for 24 hours to obtain the target sodium difluorosulfamate (23.6 g, 90% yield). [ka]

[0598] Synthesis Example 11 <Synthesis of sodium bis(2-propenyl)sulfamate (compound K)> Sodium chloride (4.2 g, 71 mmol) and dimethyl carbonate (80 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of diallylamine (8.3 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the desired crude sodium diallylsulfamate (9.7 g). The obtained crude sodium diallylsulfamate (9.7 g) was dissolved in 20 mL of methanol at 60°C, and 10 mL of dimethyl carbonate was added, and the mixture was concentrated under reduced pressure until the volume was halved. Another 14 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium diallyl sulfamate (3.9 g, 19 mmol, total yield 32%). [ka]

[0599] Synthesis Example 12 <Synthesis of sodium bispropargylsulfamate (compound L)> Sodium chloride (4.2 g, 71 mmol) and dimethyl carbonate (60 mL) were added to a reaction vessel, and chlorosulfonic acid (9.1 g, 78 mmol) was added dropwise. This solution was stirred at 80°C for 1 hour, then cooled to room temperature, and a mixed solution of dipropargylamine (7.9 g, 85 mmol) and triethylamine (8.6 g, 85 mmol) was added dropwise under an ice bath (reaction solution temperature rise 5-10°C, addition time 5-10 minutes). This solution was stirred at room temperature for 1 hour, then filtered and washed with dichloromethane to obtain the target crude sodium dipropargylsulfamate (7.1 g). The obtained crude sodium dipropargylsulfamate (7.1 g) was dissolved in 14 mL of methanol at 60°C, and 14 mL of dimethyl carbonate was added, and the mixture was concentrated under reduced pressure until the volume was halved. Another 14 mL of dimethyl carbonate was added and the mixture was concentrated under reduced pressure. When a solid precipitated, the concentration was stopped, and the mixture was filtered and washed with dimethyl carbonate to obtain the target sodium dipropargylsulfamate (3.2 g, 16 mmol, total yield 21%). [ka]

[0600] Synthesis Example 13 <Synthesis of sodium bis(trifluoromethoxysulfonyl)sulfamate (compound M)> Sodium bis(trifluoromethoxysulfonyl)imide (5.3 g, 19 mmol) and diethyl ether (25 ml) were added to a reaction vessel, and chlorosulfonic acid (2.2 g, 19 mmol) was added dropwise. After stirring the solution at room temperature, the solvent was removed to obtain the target sodium bis(trifluoromethoxysulfonyl)sulfamate. [ka]

[0601] (Preparation of electrolyte solution) Examples 1-18 and Comparative Examples 1-4 Propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed in a volume ratio of 30 / 30 / 40. The electrolyte salts shown in Table 1 were added to this mixture to a concentration of 1.2 mol / liter to obtain the basic electrolyte. Furthermore, the additives listed in Table 1 were added to this basic electrolyte to the concentrations shown in Table 1 to obtain a non-aqueous electrolyte.

[0602] (Fabrication of aluminum laminate-type sodium-ion secondary batteries) [Fabrication of the positive electrode] NaNi as a positive electrode active material 2 / 9 Cu 1 / 9 Fe 1 / 3 Mn 1 / 3 6% by mass of O2, 2% by mass of acetylene black as a conductive material, and 2% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to one side of a 15 μm thick aluminum foil that had been pre-coated with a conductive additive, dried, and roll-pressed in a press machine. The resulting slurry was then cut into shapes with an active material layer measuring 50 mm in width and 30 mm in length, and an uncoated section measuring 5 mm in width and 9 mm in length, to form the positive electrode.

[0603] [Fabrication of the negative electrode] A slurry was formed by mixing 94% by mass of hard carbon as the negative electrode active material, 1% by mass of acetylene black as the conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as the binder in an N-methylpyrrolidone solvent. The resulting slurry was coated onto 10 μm thick aluminum foil, dried, and rolled in a press. The resulting material was then cut into shapes with an active material layer measuring 52 mm in width and 32 mm in length, and an uncoated section measuring 5 mm in width and 9 mm in length, to form the negative electrode.

[0604] [Fabrication of aluminum laminate cells] A sodium-ion secondary battery was fabricated by placing the positive and negative electrodes opposite each other through a 20 μm thick microporous polyethylene film (separator), injecting the non-aqueous electrolyte obtained above, and after the non-aqueous electrolyte had sufficiently permeated the separator, sealing, pre-charging, and aging.

[0605] (Measurement of battery characteristics) [Coulomb efficiency] The sodium-ion secondary battery manufactured as described above was compressed between plates and charged at 30°C with a current equivalent to 0.1C to 3.8V (hereinafter referred to as CC / CV charging) (0.002C cut-off). Then, it was discharged to 2V with a constant current of 0.1C. This was considered one cycle, and the Coulomb efficiency for 2 to 10 cycles was calculated, with the average value being taken as the Coulomb efficiency of the battery. The results are shown in Table 1. Note that 1C represents the current value required to discharge the battery's standard capacity in one hour, and for example, 0.2C represents 1 / 5 of that current value. Coulomb efficiency is the ratio of the discharge capacity during discharge to the charge capacity during charging, expressed as a percentage.

[0606] [Capacity maintenance rate] The sodium-ion secondary batteries manufactured in Examples 4 and 12 and Comparative Example 3 were charged to 3.8V (CC / CV charge, 0.002C cut-off) at 30°C with a current equivalent to 0.1C while sandwiched between plates and pressurized. They were then discharged to 2V with a constant current of 0.1C. This was considered one cycle, and the initial discharge capacity was determined from the discharge capacity after the third cycle. The cycle was repeated, and the discharge capacity after 200 cycles was measured. The ratio of the discharge capacity after 200 cycles to the initial discharge capacity was calculated and defined as the cycle capacity retention rate (%). (Discharge capacity after 200 cycles) ÷ (Initial discharge capacity) × 100 = Capacity retention rate (%) The results are shown in Table 2.

[0607] [Table 1]

[0608] [Table 2]

Claims

1. An electrolyte for sodium-ion secondary batteries containing a compound represented by the following general formula (1). General formula (1): 【Chemistry 1】 (In the formula, R １０１ and R １０２ Each is independent of the others. -H, -F, Formula: -O ｐ１０１ -(SiR １０３ ２ O) ｎ１０１ -SiR １０４ ３ (R １０３ and R １０４ are, independently of each other, an alkyl group in which one or more hydrogens may be substituted by fluorine, an alkenyl group in which one or more hydrogens may be substituted by fluorine, an alkynyl group in which one or more hydrogens may be substituted by fluorine, or an aryl group in which one or more hydrogens may be substituted by fluorine, n101 is an integer of 0 or more, and p101 is 0 or 1. A group represented by) Alkyl alkyl groups having 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups having 6 to 15 carbon atoms, -SO ２ X １０１ (X １０１ (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or -H, -F, or other fluorine atoms.) -SO ３ X １０２ (X １０２ is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R １０１ and R １０２ A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO4. ２ X １０３ (X １０３ (is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, R １０１ and R １０２ (Except when both are -H.)

2. In the above general formula (1), R １０１ and R １０２ Each is independent of the others. -H, -F, Alkyl alkyl groups having 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, -SO ２ X １０１ (X １０１ (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or -H, -F, or other fluorine atoms.) -SO ３ X １０２ (X １０２ is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R １０１ and R １０２ A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more 2- to 6-valent heteroatoms in their structure, and one or more hydrogen atoms may be fluorine, -SO4. ２ X １０３ (X １０３ (is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. The electrolyte for a sodium-ion secondary battery according to claim 1.

3. In the above general formula (1), R １０１ and R １０２ Each is independent of the others. -H, -F, Alkyl alkyl groups having 1 to 4 carbon atoms, Alkenyl groups with 2 to 4 carbon atoms, Alkynyl groups with 2 to 4 carbon atoms, -SO ２ X １０１ (X １０１ (This is a C1-C4 alkyl group in which one or more hydrogen atoms may be substituted with fluorine, or -F.) -SO ３ X １０２ (X １０２ is an alkyl group which may have -F or one or more hydrogen atoms substituted with fluorine. R １０１ and R １０２ A substituent that is a hydrocarbon group having 4 to 5 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more oxygen atoms in their structure, and one or more hydrogen atoms may be substituted with fluorine. The electrolyte for a sodium-ion secondary battery according to claim 1 or 2.

4. In the above general formula (1), R １０１ and R １０２ Each is independent of the others. -H, -F, -CH ３ 、 -CH ２ CH ３ 、 -CH ２ CF ３ 、 -SO ２ F、 -CHH ２ CHCH ２ 、 -CH ２ CCH、 -SO ３ CF ３ 、 R １０１ and R １０２ They combine to form - (CH ２ ) ５ - A group that forms a cyclic structure with the nitrogen atom in general formula (1), or R １０１ and R １０２ They combine to form - (CH ２ ) ２ -O-(CH ２ ) ２ -It is a group that forms a cyclic structure together with the nitrogen atom in general formula (1), The electrolyte for a sodium-ion secondary battery according to claim 1 or 2.

5. The electrolyte for a sodium-ion secondary battery according to claim 1 or 2, wherein the content of the compound represented by the general formula (1) is 10% by mass or less.

6. The electrolyte for a sodium-ion secondary battery according to claim 1 or 2, wherein the content of the compound represented by the general formula (1) is 0.0001% by mass or more.

7. The electrolyte for a sodium-ion secondary battery according to claim 1 or 2, wherein the content of the compound represented by the general formula (1) is 0.05 to 2% by mass.

8. Furthermore, NaPF ６ The electrolyte for a sodium-ion secondary battery according to claim 1 or 2, comprising at least one selected from the group consisting of and sodium bis(fluorosulfonyl)imide.

9. Furthermore, the electrolyte for a sodium-ion secondary battery according to claim 1 or 2, further comprising sodium bis(fluorosulfonyl)imide.

10. Furthermore, the electrolyte for a sodium-ion secondary battery according to claim 1 or 2, comprising at least one solvent selected from the group consisting of carbonates and carboxylic acid esters.

11. A sodium-ion secondary battery comprising the electrolyte according to claim 1 or 2.

12. A module comprising a sodium-ion secondary battery according to claim 11.

13. A compound represented by the following general formula (1-1). General formula (1-1): 【Chemistry 2】 (In the formula, R ２０１ and R ２０２ Each is independent of the others. -H, -F, Formula: -O ｐ１０１ - (SiR １０３ ２ O) ｎ１０１ -SiR １０４ ３ (R １０３ and R １０４ These are groups represented by (1) an alkyl group in which one or more hydrogens may be substituted with fluorine, an alkenyl group in which one or more hydrogens may be substituted with fluorine, an alkynyl group in which one or more hydrogens may be substituted with fluorine, or an aryl group in which one or more hydrogens may be substituted with fluorine, where n101 is an integer of 0 or more, and p101 is 0 or 1. Alkyl alkyl groups having 1 to 7 carbon atoms, Alkenyl groups with 2 to 7 carbon atoms, Alkynyl groups with 2 to 7 carbon atoms, Aryl groups having 6 to 15 carbon atoms, -SO ２ X １０１ (X １０１ (This is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or -H, -F, or other fluorine atoms.) -SO ３ X １０２ (X １０２ is an alkyl group in which one or more hydrogen atoms are substituted with fluorine, or, R ２０１ and R ２０２ A substituent that is a hydrocarbon group having 2 to 7 carbon atoms, which is formed by bonding with the nitrogen atom in general formula (1), and which may contain multiple bonds, The substituents may contain one or more divalent to hexavalent heteroatoms in their structures, and one or more hydrogens may be substituted with fluorine, -SO ２ X １０３ (X １０３ is -H or -F.) or may be substituted with a functional group having 1 to 8 carbon atoms. However, R ２０１ and R ２０２ are both -H, R ２０１ and R ２０２ are both -CH ３ ; and, when one of R ２０１ and R ２０２ is -H and the other is a cyclohexyl group, except for these cases.)

14. In the above general formula (1-1), R ２０１ and R ２０２ All of them are -CH ２ CH ３ The compound according to claim 13.

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