Electrolytic solution composition, electrochemical device, secondary battery, lithium ion secondary battery, and composition

Abstract

To provide a composition for an electrolytic solution capable of suppressing resistance increase during low-temperature storage, and to provide an electrochemical device, a secondary battery and a lithium ion secondary battery using the composition for an electrolytic solution. Also provided are novel compositions.SOLUTION: A composition for an electrolytic solution, comprising a compound (M) represented by the following formula (M): (M) Rf1-COOM (wherein Rf1 is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li). ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an electrolyte composition, an electrochemical device, a secondary battery, a lithium ion secondary battery, and a composition. [Background technology]

[0002] In recent years, the trend toward lighter and smaller electrical appliances has led to the development of electrochemical devices with high energy density, such as lithium-ion secondary batteries. Furthermore, as the range of applications for electrochemical devices such as lithium-ion secondary batteries expands, improvements in their performance are required. In particular, improving battery performance will become increasingly important when lithium-ion secondary batteries are used in automobiles.

[0003] Patent Document 1 describes an electrolyte solution for lithium metal secondary batteries that contains a specific lithium salt and a non-aqueous solvent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-552481 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide an electrolyte composition that can suppress an increase in resistance during low-temperature storage, as well as an electrochemical device, a secondary battery, and a lithium-ion secondary battery that use the electrolyte composition. Another object of the present disclosure is to provide novel compositions. [Means for solving the problem]

[0006] The present disclosure (1) is a composition for an electrolyte solution containing a compound (M) represented by the following formula (M): (M)Rf 1 -COOM (In the formula, Rf1 is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li.

[0007] The present disclosure (2) relates to the Rf 1 is the composition for an electrolyte solution according to the present disclosure (1), which is HCF2-.

[0008] The present disclosure (3) provides that the compound (M) is HCF2-COOK, and The composition for an electrolyte solution according to the present disclosure (1) or (2) is at least one selected from the group consisting of HCF2-COONa.

[0009] The present disclosure (4) is the composition for an electrolyte solution according to any one of the present disclosures (1) to (3), wherein the content of the compound (M) is 0.0001 to 3 mass % relative to the composition for an electrolyte solution.

[0010] The present disclosure (5) is a composition for an electrolyte solution according to any one of the present disclosures (1) to (4), which contains a fluorinated ether (E) represented by the following formula (E): (E)Rf 2 -OR (In the formula, Rf 2 is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine.

[0011] The present disclosure (6) relates to the Rf 2 is the composition for an electrolyte solution according to the present disclosure (5), which is HCF2-CF2-.

[0012] The present disclosure (7) provides that R is -CH2-CF2-CF2H, -CH2-CH2-CH3, or -CH2-CH2-O-CF2-CF2H The composition for an electrolyte solution according to the present disclosure (5) or (6),

[0013] The present disclosure (8) provides that the fluorinated ether (E) is HCF2-CF2-O-CH2-CF2-CF2H, HCF2-CF2-O-CH2-CH2-CH3, and HCF2-CF2-O-CH2-CH2-O-CF2-CF2H The composition for an electrolyte solution according to any one of the present disclosures (5) to (7) is at least one selected from the group consisting of:

[0014] The present disclosure (9) is the composition for an electrolyte solution according to any one of the present disclosures (5) to (8), wherein the content of the fluorinated ether (E) is 0.1 to 100% by volume relative to the solvent in the composition for an electrolyte solution.

[0015] The present disclosure (10) is a composition for an electrolyte solution according to any one of the present disclosures (1) to (9), which contains at least one lithium salt selected from the group consisting of LiPF6, LiFSI, and LiTFSI.

[0016] The present disclosure (11) relates to the compound (M), HCF2-COOK, and HCF2-COONa, the content of the compound (M) is 0.0001 to 1% by mass relative to the electrolyte solution composition; HCF2-CF2-O-CH2-CF2-CF2H, HCF2-CF2-O-CH2-CH2-CH3, and HCF2-CF2-O-CH2-CH2-O-CF2-CF2H At least one fluorinated ether (E) selected from the group consisting of In the composition for an electrolyte solution according to any one of the present disclosures (1) to (10), the content of the fluorinated ether (E) is 5 to 80% by volume relative to the solvent in the composition for an electrolyte solution.

[0017] The present disclosure (12) is a secondary battery comprising the composition for an electrolyte solution according to the present disclosure (11) and lithium metal as a negative electrode active material.

[0018] The present disclosure (13) provides that the compound (M) is HCF2-COOK, and HCF2-COONa, the content of the compound (M) is 0.01 to 0.1% by mass relative to the electrolyte solution composition; HCF2-CF2-O-CH2-CF2-CF2H, HCF2-CF2-O-CH2-CH2-CH3, and HCF2-CF2-O-CH2-CH2-O-CF2-CF2H At least one fluorinated ether (E) selected from the group consisting of In the composition for an electrolyte solution according to any one of the present disclosures (1) to (10), the content of the fluorinated ether (E) is 25 to 30% by volume relative to the solvent in the composition for an electrolyte solution.

[0019] The present disclosure (14) is a secondary battery comprising the composition for an electrolyte solution according to the present disclosure (13) and a silicon material as a negative electrode active material.

[0020] The present disclosure (15) is a composition for an electrolyte solution according to any one of the present disclosures (1) to (11) and (13), which is for a secondary battery.

[0021] The present disclosure (16) is an electrochemical device including the composition for an electrolyte solution according to any one of the present disclosures (1) to (11) and (13).

[0022] The present disclosure (17) is a secondary battery including the composition for an electrolyte solution according to any one of the present disclosures (1) to (11) and (13).

[0023] The present disclosure (18) is a lithium ion secondary battery containing the composition for an electrolyte solution according to any one of the present disclosures (1) to (11) and (13).

[0024] The present disclosure (19) is a composition containing a compound (M) represented by the following formula (M) and a fluorinated ether (E) represented by the following formula (E): (M)Rf 1 -COOM (In the formula, Rf 1 is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li. (E)Rf 2 -OR (In the formula, Rf 2 is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine. [Effects of the Invention]

[0025] According to the present disclosure, it is possible to provide an electrolyte composition that can suppress an increase in resistance during low-temperature storage, as well as an electrochemical device, a secondary battery, and a lithium-ion secondary battery that use the electrolyte composition. Furthermore, according to the present disclosure, it is also possible to provide a novel composition. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present disclosure will be specifically described below.

[0027] The present disclosure relates to a composition for an electrolyte solution containing a compound (M) represented by the following formula (M): (M)Rf 1 -COOM (In the formula, Rf 1 is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li.

[0028] The composition of the present disclosure, containing compound (M), can suppress an increase in resistance during low-temperature storage in an electrochemical device. This effect is presumably achieved by the fact that compound (M) is entrained when the solvent in the electrolyte is reduced on the negative electrode to form a protective film, thereby forming a protective film with low resistance.

[0029] The composition of the present disclosure is used in an electrolytic solution, and may be either an electrolytic solution or a constituent component (additive, etc.) of an electrolytic solution. Furthermore, the composition of the present disclosure can be suitably used in electrochemical devices (particularly secondary batteries such as lithium ion secondary batteries).

[0030] In formula (M), Rf 1 is a fluoroalkyl group having 1 to 6 carbon atoms. The number of carbon atoms in the fluoroalkyl group is preferably 1 to 4, more preferably 1 to 3, still more preferably 1 or 2, and particularly preferably 1. The fluoroalkyl group may be linear or branched, but is preferably linear. Rf 1 Preferred are CF3-, HCF2-, FCH2-, CF3-CF2-, CF3-CH2-, HCF2-CH2-, FCH2-CH2-, CF3-CH2-CH2-, CF3-CF2-CH2-, HCF2-CF2-CH2-, FCH2-CF2-CH2-, and HCF2-CF2-CF2-CF2-CH2-, with HCF2- being more preferred from the viewpoint of suppressing an increase in resistance during storage at low temperatures.

[0031] In formula (M), M is an alkali metal other than Li. When M is an alkali metal other than Li, the alkali metal is contained in the coating film formed on the negative electrode. This reduces the crystallinity of the coating film, facilitating the movement of lithium ions. The alkali metal may be any of Na, K, Rb, Cs, and Fr, but Na and K are preferred, and K is more preferred, from the viewpoints of ionization tendency and ion size.

[0032] Of the compounds (M), HCF2-COONa (sodium difluoroacetate) and HCF2-COOK (potassium difluoroacetate) are preferred from the viewpoint of suppressing an increase in resistance during low-temperature storage, and potassium difluoroacetate is more preferred.

[0033] The compound (M) may be used alone or in combination of two or more kinds.

[0034] In the composition of the present disclosure, the content of compound (M) is preferably 0.0001% by mass or more and 3% by mass or less relative to the composition of the present disclosure. In order to further suppress an increase in resistance during low-temperature storage, the content of compound (M) is more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.3% by mass or less, even more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass or less.

[0035] The composition of the present disclosure preferably contains a fluorinated ether (E) represented by the following formula (E): (E)Rf 2 -OR (In the formula, Rf 2 is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine.

[0036] The combined use of compound (M) and fluorinated ether (E) can further suppress the increase in resistance during low-temperature storage. This effect is presumably due to the fact that fluorinated ether (E) suppresses the decomposition reaction of the electrolyte, thereby suppressing the formation of excessive coating, and the formation of a coating containing compound (M).

[0037] In formula (E), Rf 2 is a fluoroalkyl group having 1 to 6 carbon atoms. The number of carbon atoms in the fluoroalkyl group is preferably 1 to 4, more preferably 1 to 3, still more preferably 2 or 3, and particularly preferably 2. The fluoroalkyl group may be linear or branched, but is preferably linear. Rf 2Preferred are CF3-, CF2H-, CFH2-, CF3-CF2-, CF3-CH2-, HCF2-CH2-, HCF2-CF2-, FCH2-CH2-, CF3-CH2-CH2-, CF3-CF2-CH2-, HCF2-CF2-CH2-, FCH2-CF2-CH2-, and HCF2-CF2-CF2-CF2-CH2-, with HCF2-CF2- being more preferred from the viewpoint of suppressing an increase in resistance during storage at low temperatures.

[0038] In formula (E), R is H or an alkyl group having 1 to 6 carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 4, more preferably 1 to 3, and even more preferably 3. The alkyl group may be linear or branched, but is preferably linear. The alkyl group may have an ether bond and / or fluorine, but preferably has at least fluorine. As R, -CF3, -CF2H, -CFH2, -CH3, -CH2-CH3, -CF2-CF3, -CH2-CF3, -CH2-CF2H, -CH2-CFH2, -CH2-CH2-CH3, -CH2-CH2-CF3, -CH2-CF2-CF3, -CH2-CF2-CF2H, -CH2-CF2-CFH2, -CH2-CF2-CF2-CF2H, -CH2-CH2-O-CF2-CF2H is preferred, and from the viewpoint of suppressing an increase in resistance during low-temperature storage, -CH2-CF2-CF2H, -CH2-CH2-CH3, -CH2-CH2-O-CF2-CF2H is more preferred, -CH2-CF2-CF2H and -CH2-CH2-O-CF2-CF2H are even more preferred, with -CH2-CF2-CF2H being particularly preferred.

[0039] As the fluorinated ether (E), from the viewpoint of suppressing an increase in resistance during low-temperature storage, HCF2-CF2-O-CH2-CF2-CF2H, HCF2-CF2-O-CH2-CH2-CH3, and CF2-CF2-O-CH2-CH2-O-CF2-CF2H are preferred, and HCF2-CF2-O-CH2-CF2-CF2H and CF2-CF2-O-CH2-CH2-O-CF2-CF2H are more preferred. Furthermore, when the composition of the present disclosure is used in a secondary battery containing a silicon material as the negative electrode active material, HCF2-CF2-O-CH2-CF2-CF2H is particularly preferred, and when the composition of the present disclosure is used in a secondary battery containing a metal material (particularly lithium metal) as the negative electrode active material, CF2-CF2-O-CH2-CH2-O-CF2-CF2H is particularly preferred.

[0040] The fluorinated ether (E) may be used alone or in combination of two or more kinds. When two kinds of fluorinated ethers (E) are used in combination, it is preferable to combine HCF2-CF2-O-CH2-CH2-O-CF2-CF2H with HCF2-CF2-CH2-O-CF2-CF2H.

[0041] In the composition of the present disclosure, the content of the fluorinated ether (E) is preferably 0.1% by volume or more and 100% by volume or less relative to the solvent in the composition of the present disclosure. When the composition of the present disclosure is used as a negative electrode active material in a secondary battery containing a silicon material, the content of the fluorinated ether (E) relative to the solvent is more preferably 5% by volume or more, even more preferably 15% by volume or more, and particularly preferably 25% by volume or more, and is more preferably 80% by volume or less, even more preferably 60% by volume or less, even more preferably 40% by volume or less, and particularly preferably 30% by volume or less, in order to further suppress an increase in resistance during low-temperature storage. When the composition of the present disclosure is used as a negative electrode active material in a secondary battery containing a metal material (particularly lithium metal), the content of the fluorinated ether (E) relative to the solvent is more preferably 5% by volume or more, even more preferably 10% by volume or more, even more preferably 20% by volume or more, and particularly preferably 30% by volume or more, and is more preferably 80% by volume or less, even more preferably 60% by volume or less, and particularly preferably 50% by volume or less, in order to further suppress an increase in resistance during low-temperature storage.

[0042] The composition of the present disclosure preferably contains a solvent. The fluorinated ether (E) can be used as the solvent, but the composition may further contain a solvent other than the fluorinated ether (E).

[0043] The solvent preferably contains at least one selected from the group consisting of carbonates and carboxylic acid esters.

[0044] The carbonate may be a cyclic carbonate or a chain carbonate.

[0045] The cyclic carbonate may be a non-fluorinated cyclic carbonate or a fluorinated cyclic carbonate.

[0046] The non-fluorinated cyclic carbonate may be a non-fluorinated saturated cyclic carbonate, preferably a non-fluorinated saturated alkylene carbonate having an alkylene group with 2 to 6 carbon atoms, more preferably a non-fluorinated saturated alkylene carbonate having an alkylene group with 2 to 4 carbon atoms.

[0047] Among these, the non-fluorinated saturated cyclic carbonate is preferably 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, because of its high dielectric constant and suitable viscosity.

[0048] The non-fluorinated saturated cyclic carbonates may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0049] When the non-fluorinated saturated cyclic carbonate is contained, the content of the non-fluorinated saturated cyclic carbonate relative to the solvent is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume.

[0050] The fluorinated cyclic carbonate is a cyclic carbonate having a fluorine atom. A solvent containing the fluorinated cyclic carbonate can be suitably used even under high voltage. In this specification, the term "high voltage" refers to a voltage of 4.2 V or higher. The upper limit of the "high voltage" is preferably 5.5 V, and more preferably 5.0 V.

[0051] The fluorinated cyclic carbonate may be a fluorinated saturated cyclic carbonate or a fluorinated unsaturated cyclic carbonate.

[0052] The fluorinated saturated cyclic carbonate is a saturated cyclic carbonate having a fluorine atom, and specifically, is represented by the following general formula (A):

[0053] [ka] (In the formula, X 1 ~X 4 are the same or different and each represents -H, -CH3, -C2H5, -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond, provided that X 1 ~X 4 at least one of which is -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond. The fluorinated alkyl group is, for example, -CF3, -CF2H, -CH2F, etc.

[0054] When the composition of the present disclosure contains the above-mentioned fluorinated saturated cyclic carbonate, the oxidation resistance of the electrolyte is improved and stable and excellent charge / discharge characteristics are obtained when the composition is applied to a high-voltage lithium ion secondary battery or the like. In this specification, an "ether bond" is a bond represented by --O--.

[0055] X is a good choice due to its excellent dielectric constant and oxidation resistance. 1 ~X 4 It is preferred that one or two of the groups be -F, a fluorinated alkyl group which may have an ether bond, or a fluorinated alkoxy group which may have an ether bond.

[0056] Since it is expected to reduce viscosity at low temperatures, increase flash point, and improve solubility of electrolyte salts, X 1 ~X 4 is preferably —H, —F, a fluorinated alkyl group (a), a fluorinated alkyl group having an ether bond (b), or a fluorinated alkoxy group (c).

[0057] The fluorinated alkyl group (a) is an alkyl group in which at least one hydrogen atom has been substituted with a fluorine atom. The fluorinated alkyl group (a) preferably has 1 to 20 carbon atoms, more preferably 1 to 17 carbon atoms, still more preferably 1 to 7 carbon atoms, and particularly preferably 1 to 5 carbon atoms. If the number of carbon atoms is too large, there is a risk that the low-temperature characteristics and the solubility of the electrolyte salt may be reduced, whereas if the number of carbon atoms is too small, there may be a reduction in the solubility of the electrolyte salt, a reduction in discharge efficiency, and even an increase in viscosity.

[0058] Among the fluorinated alkyl groups (a) above, those having one carbon atom include CFH2-, CF2H-, and CF3-. In particular, CF2H- or CF3- is preferred in terms of high-temperature storage properties, and CF3- is most preferred.

[0059] The above fluorinated cyclic carbonates may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0060] When the fluorinated cyclic carbonate is contained, the content of the fluorinated cyclic carbonate relative to the solvent is preferably 5 to 90% by volume, more preferably 10 to 60% by volume, and even more preferably 15 to 45% by volume.

[0061] The chain carbonate may be a non-fluorinated chain carbonate or a fluorinated chain carbonate.

[0062] Examples of the non-fluorinated chain carbonate include hydrocarbon chain 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 ethyl phenyl carbonate. Among these, at least one selected from the group consisting of ethyl methyl carbonate, diethyl carbonate, and dimethyl carbonate is preferred.

[0063] The non-fluorinated chain carbonates may be used alone or in any combination of two or more in any ratio.

[0064] When the non-fluorinated chain carbonate is contained, the content of the non-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 solvent.

[0065] The fluorinated chain carbonate is a chain carbonate having fluorine atoms. A solvent containing the fluorinated chain carbonate can be suitably used even under high voltage.

[0066] The fluorinated chain carbonate may be a fluorinated chain carbonate represented by the general formula (B): Rf 2 OCOOR 7 (B) (In the formula, Rf 2 is a fluorinated alkyl group having 1 to 7 carbon atoms, and R 7 is an alkyl group having 1 to 7 carbon atoms which may contain a fluorine atom.

[0067] Rf 2 is a fluorinated alkyl group having 1 to 7 carbon atoms, and R 7 is an alkyl group having 1 to 7 carbon atoms which may contain a fluorine atom. The fluorinated alkyl group is an alkyl group in which at least one hydrogen atom has been substituted with a fluorine atom. 7 When is an alkyl group containing a fluorine atom, it becomes a fluorinated alkyl group. Rf 2 and R 7 The alkyl group preferably has 1 to 7 carbon atoms, more preferably 1 or 2 carbon atoms, in terms of low viscosity. If the number of carbon atoms is too large, there is a risk that the low-temperature characteristics and the solubility of the electrolyte salt may be reduced, whereas if the number of carbon atoms is too small, there may be a reduction in the solubility of the electrolyte salt, a reduction in discharge efficiency, and even an increase in viscosity.

[0068] Examples of the fluorinated alkyl group having one carbon atom include CFH2-, CF2H-, CF3-, etc. In particular, CFH2- or CF3- is preferred in terms of high-temperature storage properties.

[0069] The fluorinated alkyl group having two or more carbon atoms includes a group represented by the following general formula (d-1): R d1 -R d2 - (d-1) (In the formula, Rd1 is an alkyl group having one or more carbon atoms which may have a fluorine atom; R d2 is an alkylene group having 1 to 3 carbon atoms which may have a fluorine atom; provided that R d1 and R d2 A preferred example is a fluorinated alkyl group represented by the formula: wherein at least one of the groups has a fluorine atom, in view of good solubility of the electrolyte salt. In addition, R d1 and R d2 may further have atoms other than carbon atoms, hydrogen atoms and fluorine atoms.

[0070] R d1 R is an alkyl group having 1 or more carbon atoms which may have a fluorine atom. d1 R is preferably a linear or branched alkyl group having 1 to 6 carbon atoms. d1 The number of carbon atoms is more preferably 1 to 3.

[0071] Specific examples of preferred fluorinated alkyl groups include CF3CF2-, HCF2CF2-, H2CFCF2-, CH3CF2-, CF3CH2-, CF3CF2CF2-, HCF2CF2CF2-, H2CFCF2CF2-, CH3CF2CF2-,

[0072] Among them, Rf 2 and R 7 The fluorinated alkyl group is preferably CF3-, CF3CF2-, (CF3)2CH-, CF3CH2-, C2F5CH2-, CF3CF2CH2-, HCF2CF2CH2-, CF3CFHCF2CH2-, CFH2-, or CF2H-, and from the viewpoints of high flame retardancy and good rate characteristics and oxidation resistance, CF3CH2-, CF3CF2CH2-, HCF2CF2CH2-, CFH2-, or CF2H- is more preferred.

[0073] R 7 When R is an alkyl group that does not contain a fluorine atom, it is an alkyl group having 1 to 7 carbon atoms. 7 The alkyl group preferably has 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, in terms of low viscosity.

[0074] Examples of the alkyl group not containing a fluorine atom include CH3-, CH3CH2-, (CH3)2CH-, C3H7-, etc. Among these, CH3- and CH3CH2- are preferred in terms of low viscosity and good rate characteristics.

[0075] The 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 fluorine content is more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 35% by mass or more, and more preferably 60% by mass or less, and even more preferably 50% by mass or less. In the present disclosure, the fluorine content is determined based on the structural formula of the fluorinated chain carbonate as follows: {(number of fluorine atoms x 19) / molecular weight of fluorinated chain carbonate} x 100(%) This is the value calculated by

[0076] The fluorinated chain carbonate is preferably any one of the following compounds, because it has low viscosity.

[0077] [ka]

[0078] As the fluorinated chain carbonate, methyl 2,2,2-trifluoroethyl carbonate (F3CH2COC(=O)OCH3) is particularly preferred.

[0079] The above fluorinated chain carbonates may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0080] When the fluorinated chain carbonate is contained, the content of the 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 solvent.

[0081] The carboxylic acid ester may be a cyclic carboxylic acid ester or a chain carboxylic acid ester.

[0082] The cyclic carboxylic acid ester may be a non-fluorinated cyclic carboxylic acid ester or a fluorinated cyclic carboxylic acid ester.

[0083] The non-fluorinated cyclic carboxylic acid ester may be a non-fluorinated saturated cyclic carboxylic acid ester, and a non-fluorinated saturated cyclic carboxylic acid ester having an alkylene group having 2 to 4 carbon atoms is preferred.

[0084] Specific examples of non-fluorinated saturated cyclic carboxylic acid esters having an alkylene group having 2 to 4 carbon atoms include β-propiolactone, γ-butyrolactone, ε-caprolactone, δ-valerolactone, and α-methyl-γ-butyrolactone. Of these, γ-butyrolactone and δ-valerolactone are particularly preferred from the viewpoints of improving the degree of lithium ion dissociation and improving load characteristics.

[0085] The non-fluorinated saturated cyclic carboxylic acid esters may be used alone or in any combination of two or more in any ratio.

[0086] When the non-fluorinated saturated cyclic carboxylic acid ester is contained, the content of the non-fluorinated saturated cyclic carboxylic acid ester relative to the solvent is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, even more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume.

[0087] The chain carboxylic acid ester may be a non-fluorinated chain carboxylic acid ester or a fluorinated chain carboxylic acid ester. When the solvent contains the chain carboxylic acid ester, an increase in resistance of the electrolyte solution after high-temperature storage can be further suppressed.

[0088] Examples of the non-fluorinated chain carboxylic acid ester 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 methyl ester, methyl propionate, ethyl propionate, propyl butyl ester, methyl propionate, ethyl propionate, propyl butyl ester, methyl propyl ... 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, isobutyl acetate, and the like.

[0089] Of these, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate are preferred, and ethyl propionate and propyl propionate are particularly preferred.

[0090] The non-fluorinated chain carboxylic acid esters may be used alone or as a mixture of two or more kinds in any combination and in any ratio.

[0091] When the non-fluorinated chain carboxylic acid ester is contained, the content of the non-fluorinated chain carboxylic acid ester relative to the solvent is preferably 0 to 90% by volume, more preferably 0.001 to 90% by volume, even more preferably 1 to 60% by volume, and particularly preferably 5 to 40% by volume.

[0092] The fluorinated chain carboxylic acid ester is a chain carboxylic acid ester having a fluorine atom. A solvent containing the fluorinated chain carboxylic acid ester can be suitably used even under high voltage.

[0093] The fluorinated chain carboxylic acid esters include those represented by the following general formula: R 31 COOR 32 (In the formula, R 31 and R 32 are each independently an alkyl group having 1 to 4 carbon atoms which may contain a fluorine atom, and R 31 and R 32 At least one of which contains a fluorine atom.) is preferred from the viewpoint of compatibility with other solvents and oxidation resistance.

[0094] R 31 and R 32Examples of the fluorinated alkyl groups include non-fluorinated alkyl groups such as methyl group (-CH3), ethyl group (-CH2CH3), propyl group (-CH2CH2CH3), isopropyl group (-CH(CH3)2), normal butyl group (-CH2CH2CH2CH3), and tertiary 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, -CH2CF2CF2H, and -CH2CF2CFH2 are particularly preferred in terms of compatibility with other solvents, viscosity, and oxidation resistance.

[0095] Specific examples of the fluorinated chain carboxylic acid ester include 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 trifluoroethyl acetate, tert-butyl trifluoroacetate, and n-butyl trifluoroacetate. 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, 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, 2,2-difluorobutyl acetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, methyl heptafluorobutyrate, and the like can be exemplified by one or more of these. Among these, 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, methyl 4,4,4-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, 2,2-butyl difluoroacetate, methyl 2,2,3,3-tetrafluoropropionate, methyl 2-(trifluoromethyl)-3,3,3-trifluoropropionate, and methyl heptafluorobutyrate are preferred from the viewpoints of compatibility with other solvents and good rate characteristics, and 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.

[0096] The above fluorinated chain carboxylic acid esters may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0097] When the fluorinated chain carboxylic acid ester is contained, the content of the fluorinated chain 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 solvent.

[0098] The solvent preferably contains at least one selected from the group consisting of the cyclic carbonate, the chain carbonate, and the chain carboxylic acid ester, and more preferably contains the cyclic carbonate and at least one selected from the group consisting of the chain carbonate and the chain carboxylic acid ester. The cyclic carbonate is preferably a saturated cyclic carbonate. A composition containing a solvent having the above composition can further suppress an increase in resistance of an electrochemical device during low-temperature storage.

[0099] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the chain carbonate and the chain carboxylic acid ester, the solvent preferably contains the cyclic carbonate and at least one selected from the group consisting of the chain carbonate and the chain carboxylic acid ester in a total amount of 10 to 100% by volume, more preferably 30 to 100% by volume, and even more preferably 50 to 100% by volume.

[0100] When the solvent contains the cyclic carbonate and at least one selected from the group consisting of the chain carbonate and the chain carboxylic acid ester, the volume ratio of the cyclic carbonate to the at least one selected from the group consisting of the chain carbonate and the chain 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.

[0101] The solvent also preferably contains at least one selected from the group consisting of the non-fluorinated saturated cyclic carbonate, the non-fluorinated chain carbonate, and the non-fluorinated chain carboxylic acid ester, and more preferably contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester. An electrolyte solution containing a solvent of the above composition can be suitably used in electrochemical devices used at relatively low voltages.

[0102] When the solvent contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester, the solvent preferably contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester in a total amount of 5 to 100% by volume, more preferably 20 to 100% by volume, and even more preferably 30 to 100% by volume.

[0103] When the solvent contains the non-fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain carboxylic acid ester, the volume ratio of the non-fluorinated saturated cyclic carbonate to the at least one selected from the group consisting of the non-fluorinated chain carbonate and the non-fluorinated chain 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.

[0104] The solvent also preferably contains at least one selected from the group consisting of the fluorinated saturated cyclic carbonate, the fluorinated chain carbonate, and the fluorinated chain carboxylic acid ester, and more preferably contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester. An electrolytic solution 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.

[0105] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester, the solvent preferably contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester in a total amount of 5 to 100% by volume, more preferably 10 to 100% by volume, and even more preferably 30 to 100% by volume.

[0106] When the solvent contains the fluorinated saturated cyclic carbonate and at least one selected from the group consisting of the fluorinated chain carbonate and the fluorinated chain carboxylic acid ester, the volume ratio of the fluorinated saturated cyclic carbonate to the at least one selected from the group consisting of the fluorinated chain carbonate and the fluorinated chain 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.

[0107] Furthermore, an ionic liquid can also be used as the solvent. An "ionic liquid" is a liquid composed of ions that are a combination of organic cations and anions.

[0108] The organic cation is not particularly limited, but examples thereof include imidazolium ions such as dialkylimidazolium cations and trialkylimidazolium cations; tetraalkylammonium ions; alkylpyridinium ions; dialkylpyrrolidinium ions; and dialkylpiperidinium ions.

[0109] The anions that serve as counters to these organic cations are not particularly limited, but examples thereof 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.

[0110] The solvent is preferably a non-aqueous solvent, and the composition of the present disclosure is preferably a composition for a non-aqueous electrolyte solution. The content of the solvent in the electrolytic solution is preferably 70 to 99.999% by mass, more preferably 80% by mass or more, and more preferably 92% by mass or less.

[0111] The composition of the present disclosure preferably further contains an electrolyte salt, which may be any salt that can be used in an electrolytic solution, such as a lithium salt, an ammonium salt, a metal salt, a liquid salt (ionic liquid), an inorganic polymer salt, or an organic polymer salt.

[0112] The electrolyte salt of the electrolyte solution for lithium ion secondary batteries is preferably a lithium salt. Any lithium salt can be used, and specific examples include the following: LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiTaF6, LiWF7, LiAsF6, LiAlCl4, LiI, LiBr, LiCl, LiB 10 Cl 10 Inorganic lithium salts such as Li2SiF6, Li2PFO3, LiPO2F2, etc.; Lithium tungstates such as LiWOF5; Lithium carboxylates such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li; Lithium salts having an S=O group, such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li, lithium methyl sulfate, lithium ethyl sulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethyl sulfate; Lithium imide salts such as LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), iN(CF3SO2)2, LiN(C2F5SO2)2, lithium bisperfluoroethanesulfonylimide, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, lithium cyclic 1,2-ethanedisulfonylimide, lithium cyclic 1,3-propanedisulfonylimide, lithium cyclic 1,4-perfluorobutanedisulfonylimide, LiN(CF3SO2)(FSO2), LiN(CF3SO2)(C3F7SO2), LiN(CF3SO2)(C4F9SO2), and LiN(POF2)2; Lithium methide salts such as LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3; Other, formula: LiPF a (C n F 2n+1 )6-a (wherein a is an integer of 0 to 5, and n is an integer of 1 to 6) (for example, fluorine-containing organic lithium salts such as LiPF3(C2F5)3, LiPF3(CF3)3, LiPF3(iso-C3F7)3, LiPF5(iso-C3F7), LiPF4(CF3)2, LiPF4(C2F5)2), LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2, LiSCN, LiB(CN)4, LiB(C6H5)4, Li2(C2O4), LiP(C2O4)3, Li2B 12 F b H 12-b (b is an integer of 0 to 3), etc.

[0113] Among them, LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO2F2, FSO3Li, CF3SO3Li, iN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, Li PF3(C2F5)3 and the like are preferred because they have the effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, etc., and at least one lithium salt selected from the group consisting of LiPF6, LiN(FSO2)2 (lithium bis(fluorosulfonyl)imide (LIFSI)) and LiN(CF3SO2)2 (lithium bis(trifluoromethanesulfonyl)imide (LITFSI)) is more preferred, with at least one lithium salt selected from the group consisting of LiPF6, LiFSI and LiTFSI being particularly preferred.

[0114] These electrolyte salts may be used alone or in combination of two or more. A preferred example of a combination of two or more is a combination of LiPF6 and LiBF4, or a combination of LiPF6 and LiPO2F2, C2H5OSO3Li or FSO3Li, which has the effect of improving high-temperature storage characteristics, load characteristics and cycle characteristics.

[0115] In this case, there is no limit to the amount of LiBF4, LiPO2F2, C2H5OSO3Li, or FSO3Li blended relative to 100% by mass of the entire electrolyte solution, and it can be any amount as long as it does not significantly impair the effects of the present disclosure. However, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the electrolyte solution.

[0116] Another example is the combined use of an inorganic lithium salt and an organic lithium salt, which has the effect of suppressing deterioration due to high-temperature storage. Preferred organic lithium salts include CF3SO3Li, LiN(FSO2)2(LIFSI), LiN(FSO2)(CF3SO2), LiN(CF3SO2)2(LITFSI), LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, and LiPF3(C2F5)3. In this case, the proportion of the organic lithium salt relative to 100% by mass of the entire electrolyte solution is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and is preferably 30% by mass or less, particularly preferably 20% by mass or less.

[0117] The concentration of these electrolyte salts in the electrolyte solution is not particularly limited as long as it does not impair the effects of the present disclosure. In order to maintain the electrical conductivity of the electrolyte solution in a good range and ensure good battery performance, the total molar concentration of lithium in the electrolyte solution 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, particularly preferably 1.0 mol / L or more, and is preferably 3 mol / L or less, more preferably 2.5 mol / L or less, even more preferably 2.0 mol / L or less.

[0118] If the total molar concentration of lithium is too low, the electrical conductivity of the electrolyte may be insufficient, whereas if the concentration is too high, the electrical conductivity may decrease due to increased viscosity, which may result in reduced battery performance.

[0119] The electrolyte salt of the electrolytic solution for the electric double layer capacitor is preferably an ammonium salt. Examples of the ammonium salt include the following (IIa) to (IIe). (IIa) Tetraalkyl quaternary ammonium salts General formula (IIa):

[0120] [ka] (In the formula, R 1a , R 2a , R 3a and R 4a are the same or different, and each represents an alkyl group having 1 to 6 carbon atoms which may contain an ether bond; X - is an anion) Preferred examples include tetraalkyl quaternary ammonium salts represented by the following formula: In addition, ammonium salts in which some or all of the hydrogen atoms have been substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improving oxidation resistance.

[0121] Specific examples include compounds represented by the general formula (IIa-1):

[0122] [ka] (In the formula, R 1a , R 2a and X - is the same as above; x and y are the same or different and are integers of 0 to 4, and x+y=4) tetraalkyl quaternary ammonium salts represented by general formula (IIa-2):

[0123] [ka] (In the formula, R 5a is an alkyl group having 1 to 6 carbon atoms; R 6a is a divalent hydrocarbon group having 1 to 6 carbon atoms; R 7a is an alkyl group having 1 to 4 carbon atoms; z is 1 or 2; X - is an anion) an alkyl ether group-containing trialkylammonium salt represented by the formula: By introducing an alkyl ether group, it is possible to reduce the viscosity.

[0124] Anion X - may be an inorganic anion or an organic anion. Inorganic anions include, for example, AlCl4 - , BF4 - , PF6 - , AsF6 - , TaF6 - , I - , SbF6 - Examples of organic anions include bisoxalatoborate anion, difluorooxalatoborate anion, tetrafluorooxalatophosphate anion, difluorobisoxalatophosphate anion, CF3COO - , CF3SO3 - , (CF3SO2)2N - , (C2F5SO2)2N - etc.

[0125] Among these, BF4 is the most popular due to its excellent oxidation resistance and ionic dissociation properties. -, PF6 - , AsF6 - , SbF6 - is preferred.

[0126] Specific preferred examples of tetraalkyl quaternary ammonium salts include EtNBF, EtNClO, EtNPF, EtNAsF, EtNSbF, EtNCFSO, EtN(CFSO)N, EtNCFSO, EtMeNBF, EtMeNClO, EtMeNPF, EtMeNAsF, EtMeNSbF, EtMeNCFSO, EtMeN(CFSO)N, and EtMeNCFSO, and particularly include EtNBF, EtNPF, EtNSbF, EtNAsF, EtMeNBF, and N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium salt.

[0127] (IIb) Spirocyclic bipyrrolidinium salts General formula (IIb-1):

[0128] [ka] (In the formula, R 8a and R 9a are the same or different, and each is an alkyl group having 1 to 4 carbon atoms; X - is an anion; n1 is an integer from 0 to 5; n2 is an integer from 0 to 5) spirocyclic bipyrrolidinium salts represented by general formula (IIb-2):

[0129] [ka] (In the formula, R 10a and R 11a are the same or different, and each is an alkyl group having 1 to 4 carbon atoms; X - is an anion; n3 is an integer from 0 to 5; n4 is an integer from 0 to 5) or a spirocyclic bipyrrolidinium salt represented by general formula (IIb-3):

[0130] [ka] (In the formula, R 12a and R 13a are the same or different, and each is an alkyl group having 1 to 4 carbon atoms; X - is an anion; n5 is an integer from 0 to 5; n6 is an integer from 0 to 5) In addition, spirocyclic bipyrrolidinium salts in which some or all of the hydrogen atoms have been substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improving oxidation resistance.

[0131] Anion X - Preferred examples of (IIa) are the same as those of (IIa). Among them, BF4-, PF6-, (CF3SO2)2N-, or (C2F5SO2)2N- are preferred because of their high dissociation property and low internal resistance under high voltage.

[0132] Preferable specific examples of the spirocyclic bipyrrolidinium salt include, for example, [ka] etc.

[0133] This spirocyclic bipyrrolidinium salt is excellent in solubility in solvents, oxidation resistance, and ionic conductivity.

[0134] (IIc) Imidazolium salts General formula (IIc):

[0135] [ka] (In the formula, R 14a and R 15a are the same or different, and each is an alkyl group having 1 to 6 carbon atoms; X - is an anion) A preferred example is an imidazolium salt represented by the following formula: In addition, imidazolium salts in which some or all of the hydrogen atoms have been substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improving oxidation resistance.

[0136] Anion X - The preferred examples of (IIa) are the same as those of (IIa).

[0137] Preferred examples include

[0138] [ka] etc.

[0139] This imidazolium salt is excellent in that it has low viscosity and good solubility.

[0140] (IId): N-alkylpyridinium salts General formula (IId):

[0141] [ka] (In the formula, R 16a is an alkyl group having 1 to 6 carbon atoms; X - is an anion) Preferred examples include N-alkylpyridinium salts represented by the following formula: In addition, N-alkylpyridinium salts in which some or all of the hydrogen atoms have been substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improving oxidation resistance.

[0142] Anion X - The preferred examples of (IIa) are the same as those of (IIa).

[0143] Preferred examples include

[0144] [ka] etc.

[0145] This N-alkylpyridinium salt is excellent in that it has low viscosity and good solubility.

[0146] (IIe) N,N-Dialkylpyrrolidinium Salts General formula (IIe):

[0147] [ka] (In the formula, R 17a and R 18a are the same or different, and each is an alkyl group having 1 to 6 carbon atoms; X - is an anion) Preferred examples include N,N-dialkylpyrrolidinium salts represented by the following formula: Furthermore, N,N-dialkylpyrrolidinium salts in which some or all of the hydrogen atoms have been substituted with fluorine atoms and / or fluorine-containing alkyl groups having 1 to 4 carbon atoms are also preferred from the viewpoint of improving oxidation resistance.

[0148] Anion X - The preferred examples of (IIa) are the same as those of (IIa).

[0149] Preferred examples include

[0150] [ka]

[0151] [ka] etc.

[0152] This N,N-dialkylpyrrolidinium salt is excellent in that it has low viscosity and good solubility.

[0153] Among these ammonium salts, (IIa), (IIb) and (IIc) are preferred in terms of solubility, oxidation resistance and ionic conductivity.

[0154] [ka] (wherein Me is a methyl group; Et is an ethyl group; X - , x and y are the same as in formula (IIa-1) is preferred.

[0155] Furthermore, a lithium salt may be used as the electrolyte salt for the electric double layer capacitor. Preferred examples of the lithium salt include LiPF6, LiBF4, LiN(FSO2)2, LiAsF6, LiSbF6, and LiN(SO2C2H5)2. To further improve the capacity, a magnesium salt may be used, and preferred examples of the magnesium salt include Mg(ClO4)2 and Mg(OOC2H5)2.

[0156] When the electrolyte salt is an ammonium salt, the concentration is preferably 0.7 mol / L or more. If the concentration is less than 0.7 mol / L, not only will the low-temperature characteristics deteriorate but the initial internal resistance may also increase. The concentration of the electrolyte salt is more preferably 0.9 mol / L or more. The upper limit of the concentration is preferably 2.0 mol / L or less, and more preferably 1.5 mol / L or less, from the viewpoint of low-temperature characteristics. When the ammonium salt is triethylmethylammonium tetrafluoroborate (TEMABF4), the concentration is preferably 0.7 to 1.5 mol / L in terms of excellent low-temperature properties. In the case of spirobipyrrolidinium tetrafluoroborate (SBPBF4), the concentration is preferably 0.7 to 2.0 mol / liter.

[0157] The compositions of the present disclosure have the general formula (2): [ka] (In the formula, X 21 is a group containing at least H or C, n21 is an integer of 1 to 3, Y 21 and Z 21 are the same or different and are groups containing at least H, C, O or F; n22 is 0 or 1; Y 21 and Z 21 may be bonded to each other to form a ring.) When the electrolyte solution contains compound (2), the capacity retention rate is more unlikely to decrease and the amount of gas generated is more unlikely to increase even when stored at high temperatures.

[0158] If n21 is 2 or 3, then 2 or 3 Xs 21 may be the same or different. Y 21 and Z 21 If there are multiple Ys, there are multiple Ys. 21 and Z 21 may be the same or different.

[0159] X 21 As for -CY 21 Z 21 -(In the formula, Y 21 and Z 21 as above) or -CY 21 =CZ 21 -(In the formula, Y 21 and Z 21 is as defined above) is preferred.

[0160] Y 21 is preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-. Z 21 is preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2- and CF3CF2CF2-.

[0161] Or Y 21 and Z 21 can be bonded to each other to form a carbocyclic or heterocyclic ring which may contain an unsaturated bond and which may have aromaticity. The number of carbon atoms in the ring is preferably 3 to 20.

[0162] Next, specific examples of compound (2) will be described. In the following examples, the term "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure within the scope of the present disclosure, and examples thereof include a dimer, trimer, tetramer, etc. composed of multiple acid anhydrides, structural isomers such as those having the same number of carbon atoms in the substituent but having a branched chain, and those in which the substituent is bonded to the acid anhydride at a different position.

[0163] Specific examples of acid anhydrides forming a five-membered ring structure include succinic anhydride, methylsuccinic anhydride (4-methylsuccinic anhydride), dimethylsuccinic anhydride (4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride, etc.), 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5-divinylsuccinic anhydride, phenylsuccinic anhydride (4-phenylsuccinic anhydride), 4,5-diphenylsuccinic anhydride, Examples of the maleic anhydride include 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 the like, and their analogs.

[0164] Specific examples of acid anhydrides forming a 6-membered ring structure include cyclohexanedicarboxylic anhydride (cyclohexane-1,2-dicarboxylic anhydride, etc.), 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride, glutaconic anhydride, 2-phenylglutaric anhydride, and the like, and their analogs.

[0165] Specific examples of other acid anhydrides forming a cyclic structure include 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic acid anhydride, diglycolic acid anhydride, and analogs thereof.

[0166] Specific examples of acid anhydrides that form a cyclic structure and are substituted with a halogen atom include monofluorosuccinic anhydride (4-fluorosuccinic anhydride, etc.), 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 analogs thereof.

[0167] Compound (2) may, among others, be 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 Preferred are maleic anhydride, phenylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, dimethylsuccinic anhydride, trifluoromethylsuccinic anhydride, monofluorosuccinic anhydride, and tetrafluorosuccinic anhydride, of which maleic anhydride, methylmaleic anhydride, trifluoromethylmaleic anhydride, succinic anhydride, methylsuccinic anhydride, trifluoromethylsuccinic anhydride, and tetrafluorosuccinic anhydride are more preferred, and maleic anhydride and succinic anhydride are even more preferred.

[0168] Compound (2) is represented by the general formula (3):

[0169] [ka] (In the formula, X 31 ~X 34 are the same or different and contain at least H, C, O or F), and a compound (3) represented by the general formula (4):

[0170] [ka] (In the formula, X 41 and X 42 are the same or different and contain at least H, C, O or F).

[0171] X 31 ~X 34are the same or different and are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group, and a fluorinated alkenyl group. 31 ~X 34 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0172] X 31 ~X 34 are the same or different, and are more preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2-.

[0173] X 41 and X 42 are the same or different and are preferably at least one selected from the group consisting of an alkyl group, a fluorinated alkyl group, an alkenyl group, and a fluorinated alkenyl group. 41 and X 42 The number of carbon atoms is preferably 1 to 10, and more preferably 1 to 3.

[0174] X 41 and X 42 are the same or different, and are more preferably at least one selected from the group consisting of H-, F-, CH3-, CH3CH2-, CH3CH2CH2-, CF3-, CF3CF2-, CH2FCH2-, and CF3CF2CF2-.

[0175] Compound (3) is preferably any one of the following compounds:

[0176] [ka]

[0177] Compound (4) is preferably any one of the following compounds:

[0178] [ka]

[0179] The composition preferably contains 0.0001 to 15% by mass of compound (2) relative to the electrolyte solution, since this prevents a decrease in capacity retention and an increase in the amount of gas generated even when stored at high temperatures. The content of compound (2) 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.

[0180] When the composition contains both compounds (3) and (4), even when stored at high temperatures, the capacity retention rate is unlikely to decrease and the amount of gas generated is unlikely to increase. Therefore, the electrolyte preferably contains 0.08 to 2.50 mass% of compound (3) and 0.02 to 1.50 mass% of compound (4), and more preferably 0.80 to 2.50 mass% of compound (3) and 0.08 to 1.50 mass% of compound (4).

[0181] The composition of the present 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 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 have been substituted with halogen atoms. n represents an integer of 1 to 10. [ka] (In the formula, R c represents a hydrogen atom, a halogen atom, an alkyl group, an alkyl group in which at least some of the hydrogen atoms have been substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 is an alkylene group, X c1 represents an oxygen atom or a sulfur atom. dand R e each independently represents a hydrogen atom, a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms have been substituted with halogen atoms, and m represents an integer of 1 to 10. [ka] (In the formula, R f , R g , R h and R i each 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 have been substituted with halogen atoms. f , R g , R h and R i At least one of the groups is a group containing a cyano group. l represents an integer of 1 to 3. This can improve the high-temperature storage properties of the electrochemical device.The above nitrile compounds may be used alone or in any combination of two or more kinds in any ratio.

[0182] In the above general formula (1a), R a and R b are each independently 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 have been substituted with halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, with fluorine being preferred. The alkyl group preferably has a carbon number of 1 to 5. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group. Examples of the group in which at least some of the hydrogen atoms of an alkyl group have been substituted with halogen atoms include the above-mentioned groups in which at least some of the hydrogen atoms of the alkyl group have been substituted with the above-mentioned halogen atoms. R a and R bis an alkyl group or an alkyl group in which at least some of the hydrogen atoms are substituted with halogen atoms, R a and R b may be bonded to each other to form a ring structure (for example, a cyclohexane ring). R a and R b is preferably a hydrogen atom or an alkyl group.

[0183] In the above general formula (1a), n is an integer of 1 to 10. When n is 2 or more, n R a may all be the same, or at least some may be different. b The same applies to n. n is preferably an integer of 1 to 7, and more preferably an integer of 2 to 5.

[0184] As the nitrile compound represented by the above general formula (1a), dinitriles and tricarbonitriles are preferred. Specific examples of dinitriles include malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, 2,4-dimethylsuccinonitrile, 2,5-dimethylsuccinonitrile, 2,6-dimethylsuccinonitrile, 2,7-dimethylsuccinonitrile, 2,8-dimethylsuccinonitrile, 2,9-dimethylsuccinonitrile, 2,10-dimethylsuccinonitrile, 2,11-dimethylsuccinonitrile, 2,12-dimethylsuccinonitrile, 2,13-dimethylsuccinonitrile, 2,14-dimethylsuccinonitrile, 2,15-dimethylsuccinonitrile, 2,16-dimethylsuccinonitrile, 2,17-dimethylsuccinonitrile, 2,18-dimethylsuccinonitrile, 2,19-dimethylsuccinonitrile, 2,20-dimethylsuccinonitrile, 2,21-dimethylsuccinonitrile, 2,22-dimethylsuccinonitrile, 2,31-dimethylsuccinonitrile, 2,23-dimethylsuccinonitrile, 2,24-dimethylsuccinonitrile, 2,25-dimethylsuccinonitrile, 2,26-dimethylsuccinonitrile, 2,27-dimethylsuccinonitrile, 2,28-dimethylsuccinonitrile, 2,29-dimethylsuccinonitrile, 2,30-dimethylsuccinonitrile, 2,31-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- Dimethylsuccinonitrile, 2,2-diisobutyl-3,3-dimethylsuccinonitrile, 2-methylglutaronitrile, 2,3-dimethylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,3,3-tetramethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 2,2,3,4-tetramethylglutaronitrile, 2,3,3,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 2,6-dicyanopentane Examples include cyclohexyl heptane, 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. Among these, succinonitrile, glutaronitrile, and adiponitrile are particularly preferred. Specific examples of tricarbonitrile include pentanetricarbonitrile, propanetricarbonitrile, 1,3,5-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, heptanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, cyclohexanetricarbonitrile, triscyanoethylamine, triscyanoethoxypropane, tricyanoethylene, and tris(2-cyanoethyl)amine. Particularly preferred are 1,3,6-hexanetricarbonitrile and cyclohexanetricarbonitrile, and most preferred is cyclohexanetricarbonitrile.

[0185] In the above general formula (1b), R c represents a hydrogen atom, a halogen atom, an alkyl group, an alkyl group in which at least some of the hydrogen atoms have been substituted with halogen atoms, or NC-R c1 -X c1 -(R c1 is an alkylene group, X c1 represents an oxygen atom or a sulfur atom, and R d and R e are each independently a hydrogen atom, a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms have been 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 have been substituted with halogen atoms include those exemplified for the general formula (1a) above. Above NC-R c1 -X c1 -R in c1 is an alkylene group. The alkylene group is preferably an alkylene group having 1 to 3 carbon atoms. R c , R d and R e are preferably each independently a hydrogen atom, a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms have been substituted with halogen atoms. R c , R d and R eAt least one of the above is preferably a halogen atom or a group in which at least some of the hydrogen atoms of an alkyl group have been substituted with halogen atoms, and more preferably a fluorine atom or a group in which at least some of the hydrogen atoms of an alkyl group have been substituted with fluorine atoms. R d and R e is an alkyl group or an alkyl group in which at least some of the hydrogen atoms are substituted with halogen atoms, R d and R e may be bonded to each other to form a ring structure (for example, a cyclohexane ring).

[0186] In the above general formula (1b), m is an integer of 1 to 10. When m is 2 or more, m R d may all be the same, or at least some may be different. e The same applies to m. m is preferably an integer of 2 to 7, and more preferably an integer of 2 to 5.

[0187] Examples of the nitrile compound represented by the general formula (1b) include acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 3-methoxypropionitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 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, etc. Among these, 3,3,3-trifluoropropionitrile is particularly preferred.

[0188] In the above general formula (1c), Rf , R g , R h and R i are each independently a group containing a cyano group (CN), a hydrogen atom, a halogen atom, an alkyl group, or an alkyl group in which at least some of the hydrogen atoms have been 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 have been substituted with halogen atoms include those exemplified for the general formula (1a) above. Examples of the cyano group-containing group include a cyano group and an alkyl group in which at least some of the hydrogen atoms have been substituted with a cyano group. Examples of the alkyl group in this case include those exemplified for the general formula (1a) above. R f , R g , R h and R i At least one of R is a group containing a cyano group. f , R g , R h and R i At least two of R are groups containing a cyano group, and more preferably, R h and R i is a group containing a cyano group. h and R i is a group containing a cyano group, R f and R g is preferably a hydrogen atom.

[0189] In the general formula (1c), l is an integer of 1 to 3. When l is 2 or more, l R f may all be the same, or at least some may be different. g The same applies to l. l is preferably an integer of 1 to 2.

[0190] Examples of the nitrile compound represented by the general formula (1c) include 3-hexenedinitrile, mucononitrile, maleonitrile, fumaronitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, and 2-hexenenitrile, of which 3-hexenedinitrile and mucononitrile are preferred, and 3-hexenedinitrile is particularly preferred.

[0191] The content of the nitrile compounds is preferably 0.2 to 7% by mass relative to the electrolytic solution. This can further improve the high-temperature storage characteristics and safety of electrochemical devices at high voltages. The lower limit of the total content of the nitrile compounds 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.

[0192] The composition of the present disclosure may contain a compound having an isocyanato group (hereinafter, sometimes abbreviated as "isocyanate"). The isocyanate is not particularly limited, and any isocyanate can be used. Examples of isocyanates include monoisocyanates, diisocyanates, triisocyanates, etc.

[0193] Specific examples of monoisocyanates include isocyanatomethane, isocyanatoethane, 1-isocyanatopropane, 1-isocyanatobutane, 1-isocyanatopentane, 1-isocyanatohexane, 1-isocyanatoheptane, 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.

[0194] Specific examples of diisocyanato include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 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. hexane, 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)cyclohexane (methyl)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 bis(methyl isocyanate), bicyclo[2.2.1]heptane-2,5-diylbis(methyl isocyanate), bicyclo[2.2.1]heptane-2,6-diylbis(methyl isocyanate), 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, octamethylene diisocyanate, tetramethylene diisocyanate, and the like.

[0195] Specific examples of triisocyanates include 1,6,11-triisocyanatoundecane, 4-isocyanatomethyl-1,8-octamethylene diisocyanate, 1,3,5-triisocyanatomethylbenzene, 1,3,5-tris(6-isocyanatohex-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 4-(isocyanatomethyl)octamethylene diisocyanate.

[0196] Among these, 1,6-diisocyanatohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,3,5-tris(6-isocyanatohex-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 easily available industrially and can keep the production costs of the electrolyte low. Furthermore, from a technical viewpoint, they can contribute to the formation of a stable coating structure, and are therefore more preferably used.

[0197] The isocyanate content is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but is preferably 0.001% by mass or more and 1.0% by mass or less relative to the composition. When the isocyanate content is above this lower limit, a sufficient effect of improving the cycle characteristics of the nonaqueous electrolyte secondary battery can be achieved. Furthermore, when the isocyanate content is below this upper limit, an increase in the initial resistance of the nonaqueous electrolyte secondary battery 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.

[0198] The composition of the present disclosure may contain a cyclic sulfonate ester. The cyclic sulfonate ester is not particularly limited, and any cyclic sulfonate ester can be used. Examples of the cyclic sulfonate ester include saturated cyclic sulfonate esters, unsaturated cyclic sulfonate esters, saturated cyclic disulfonate esters, and unsaturated cyclic disulfonate esters.

[0199] Specific examples of saturated cyclic sulfonic acid esters include 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, and 2,4-butane sultone.

[0200] Specific examples of the unsaturated cyclic sulfonic acid ester 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- 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-propene sultone, 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 thereof include 1-methyl-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.

[0201] Among these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, and 1-propene-1,3-sultone are more preferably used because they are easily available and can contribute to the formation of a stable coating structure. The content of the cyclic sulfonate ester is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present disclosure, but is preferably 0.001% by mass or more and 3.0% by mass or less with respect to the electrolytic solution.

[0202] When the content of the cyclic sulfonate ester is equal to or greater than this lower limit, the cycle characteristics of the non-aqueous electrolyte secondary battery can be sufficiently improved. When the content is equal to or less than this upper limit, an increase in the manufacturing cost of the non-aqueous electrolyte secondary battery can be avoided. The content of the cyclic sulfonate ester is more preferably equal to or greater than 0.01% by mass, even more preferably equal to or greater than 0.1% by mass, particularly preferably equal to or greater than 0.2% by mass, and more preferably equal to or less than 2.5% by mass, even more preferably equal to or less than 2.0% by mass, particularly preferably equal to or less than 1.8% by mass.

[0203] The composition of the present disclosure may further contain polyethylene oxide having a weight average molecular weight of 2000 to 4000 and having —OH, —OCOOH, or —COOH at its terminal. By including such a compound, the stability of the electrode interface can be improved, and the characteristics of the electrochemical device can be improved. Examples of the polyethylene oxide include polyethylene oxide monool, polyethylene oxide carboxylic acid, polyethylene oxide diol, polyethylene oxide dicarboxylic acid, polyethylene oxide triol, polyethylene oxide tricarboxylic acid, etc. These may be used alone or in combination of two or more. Among these, a mixture of polyethylene oxide monool and polyethylene oxide diol, and a mixture of polyethylene carboxylic acid and polyethylene dicarboxylic acid are preferred in terms of improving the properties of the electrochemical device.

[0204] If the weight-average molecular weight of the polyethylene oxide is too small, it may be susceptible to oxidative decomposition.The weight-average molecular weight is more preferably 3,000 to 4,000. The weight average molecular weight can be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0205] The content of the polyethylene oxide in the composition is 1 × 10 -6 ~1×10 -2 If the content of polyethylene oxide is too high, the properties of the electrochemical device may be impaired. The content of the polyethylene oxide is 5 x 10 -6 It is more preferable that it is mol / kg or more.

[0206] The composition of the present disclosure may further contain, as an additive, a fluorinated saturated cyclic carbonate, an unsaturated cyclic carbonate, an overcharge inhibitor, or other known auxiliary agents, etc. This can suppress deterioration of the properties of the electrochemical device.

[0207] Examples of fluorinated saturated cyclic carbonates include compounds represented by the general formula (A) described above. Among them, 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. One type of fluorinated saturated cyclic carbonate may be used alone, or two or more types may be used in any combination and ratio.

[0208] The content of the fluorinated saturated cyclic carbonate in the composition 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.

[0209] Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, and catechol carbonates.

[0210] 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, ethynyl ethylene carbonate, propargyl ethylene carbonate, methyl vinylene carbonate, and dimethyl vinylene carbonate.

[0211] Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene carbonate, Examples of the ethylene carbonate include 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.

[0212] Among these, preferred unsaturated cyclic carbonates are 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-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, and 4-vinyl-5-ethynyl ethylene carbonate. Furthermore, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are particularly preferred because they form a more stable interface protective film, with vinylene carbonate being the most preferred.

[0213] The molecular weight of the unsaturated cyclic carbonate is not particularly limited and may be any as long as it does not significantly impair the effects of the present disclosure. The molecular weight is preferably 50 or more and 250 or less. Within this range, the solubility of the unsaturated cyclic carbonate in the electrolyte solution is easily ensured, and the effects of the present disclosure are easily exhibited. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or more and more preferably 150 or less.

[0214] The method for producing the unsaturated cyclic carbonate is not particularly limited, and any known method can be selected for production.

[0215] The unsaturated cyclic carbonates may be used alone or in any combination of two or more in any ratio.

[0216] The content of the unsaturated cyclic carbonate is not particularly limited and may be any content as long as it does not significantly impair the effects of the present 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, based on 100% by mass of the composition. 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 solution are likely to exhibit sufficient improvement in cycle characteristics, and it is also easy to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity retention rate.

[0217] As the unsaturated cyclic carbonate, in addition to the non-fluorinated unsaturated cyclic carbonates as described above, fluorinated unsaturated cyclic carbonates can also be suitably used. The fluorinated unsaturated cyclic carbonate is a cyclic carbonate having an unsaturated bond and a fluorine atom. The number of fluorine atoms in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. Among them, the number of fluorine atoms is usually 6 or less, preferably 4 or less, and most preferably 1 or 2.

[0218] Examples of the fluorinated unsaturated cyclic carbonate include fluorinated vinylene carbonate derivatives and fluorinated ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon double bond.

[0219] 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.

[0220] Examples of fluorinated ethylene carbonate derivatives substituted with a substituent 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, 4,5-difluoro-4-allylethylene carbonate, and 4,5-difluoro-4-vinylethylene carbonate. Examples of the fluorocarbon polymerizable monomer include 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.

[0221] Among them, examples of 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 stable interface protective coatings.

[0222] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and may be any value as long as it does not significantly impair the effects of the present disclosure. The molecular weight is preferably 50 or more and 500 or less. Within this range, the solubility of the fluorinated unsaturated cyclic carbonate in the electrolyte solution is easily ensured.

[0223] The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and any known method can be selected for production. The molecular weight is more preferably 100 or more and more preferably 200 or less.

[0224] The fluorinated unsaturated cyclic carbonate may be used alone or in any combination and ratio of two or more. The content of the fluorinated unsaturated cyclic carbonate is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present disclosure. The content of the fluorinated unsaturated cyclic carbonate is typically, based on 100 mass% of the composition, preferably 0.001 mass% or more, more preferably 0.01 mass% or more, even more preferably 0.1 mass% or more, and preferably 5 mass% or less, more preferably 4 mass% or less, and even more preferably 3 mass% or less. Within this range, electrochemical devices using the electrolyte solution are likely to exhibit sufficient improvement in cycle characteristics, and it is also likely to avoid situations such as a decrease in high-temperature storage characteristics, an increase in gas generation, and a decrease in discharge capacity retention rate.

[0225] The composition of the present disclosure may contain a compound having a triple bond. The type of compound is not particularly limited as long as it has one or more triple bonds in the molecule. Specific examples of the compound having a triple bond include the following compounds: hydrocarbon compounds such as 1-pentyne, 2-pentyne, 1-hexyne, 2-hexyne, 3-hexyne, 1-heptyne, 2-heptyne, 3-heptyne, 1-octyne, 2-octyne, 3-octyne, 4-octyne, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-dodecyne, 2-dodecyne, 3-dodecyne, 4-dodecyne, 5-dodecyne, phenylacetylene, 1-phenyl-1-propyne, 1-phenyl-2-propyne, 1-phenyl-1-butyne, 4-phenyl-1-butyne, 4-phenyl-1-butyne, 1-phenyl-1-pentyne, 5-phenyl-1-pentyne, 1-phenyl-1-hexyne, 6-phenyl-1-hexyne, diphenylacetylene, 4-ethynyltoluene, and dicyclohexylacetylene;

[0226] 2-Propynyl methyl carbonate, 2-propynyl ethyl carbonate, 2-propynyl propyl carbonate, 2-propynyl butyl carbonate, 2-propynyl phenyl carbonate, 2-propynyl cyclohexyl carbonate, di-2-propynyl carbonate, 1-methyl-2-propynyl methyl carbonate, 1,1-dimethyl-2-propynyl methyl carbonate, 2-butynyl methyl carbonate, 3-butynyl methyl carbonate, 2-pentynyl methyl carbonate monocarbonates such as 2-butyne-1,4-diol dimethyl dicarbonate, 2-butyne-1,4-diol diethyl dicarbonate, 2-butyne-1,4-diol dipropyl dicarbonate, 2-butyne-1,4-diol dibutyl dicarbonate, 2-butyne-1,4-diol diphenyl dicarbonate, and 2-butyne-1,4-diol dicyclohexyl dicarbonate;

[0227] 2-Propynyl acetate, 2-Propynyl propionate, 2-Propynyl butyrate, 2-Propynyl benzoate, 2-Propynyl cyclohexylcarboxylate, 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 cyclohexylcarboxylate, 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-propynoate, ethyl 2-propynoate, propyl 2-propynoate, vinyl 2-propynoate, 2-propenyl 2-propynoate, 2-butenyl 2-propynoate, 3-butenyl 2-propynoate, 2 Methyl 2-butynoate, Ethyl 2-butynoate, Propyl 2-butynoate, Vinyl 2-butynoate, 2-Propenyl 2-butynoate, 2-Butenyl 2-butynoate, 3-Butenyl 2-butynoate, Methyl 3-butynoate, Ethyl 3-butynoate, Propyl 3-butynoate, Vinyl 3-butynoate, 2-Propenyl 3-butynoate, 2-Butenyl 3-butynoate, 3-Butenyl 3-butynoate, Methyl 2-pentynoate, Ethyl 2-pentynoate, Propyl 2-pentynoate, Vinyl 2-pentynoate, 2-Propenyl 2-pentynoate, 2-Butenyl 2-pentynoate monocarboxylic acid esters such as 2-pentynoate, 3-butenyl 2-pentynoate, methyl 3-pentynoate, ethyl 3-pentynoate, propyl 3-pentynoate, vinyl 3-pentynoate, 2-propenyl 3-pentynoate, 2-butenyl 3-pentynoate, 3-butenyl 3-pentynoate, methyl 4-pentynoate, ethyl 4-pentynoate, propyl 4-pentynoate, vinyl 4-pentynoate, 2-propenyl 4-pentynoate, 2-butenyl 4-pentynoate, 3-butenyl 4-pentynoate, fumaric acid esters, methyl trimethylacetate, ethyl trimethylacetate;

[0228] 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-dioxido-1,2-oxathiolan-4-yl acetate, 2,2-dioxido-1,2-oxathiolan-4-yl acetate, etc.;

[0229] oxalic acid 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-butynylvinyl oxalate, allyl 2-butynyl oxalate, di-2-butynyl oxalate, 3-butynylmethyl oxalate, 3-butynylethyl oxalate, 3-butynylpropyl oxalate, 3-butynylvinyl oxalate, allyl 3-butynyl oxalate, and di-3-butynyl oxalate;

[0230] 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;

[0231] 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-propenyl 2-propynyl(2-propenyl)phosphinate, and 3-butenyl 2-propynyl(2-propenyl)phosphinate;

[0232] Methyl 2-propenylphosphonate, methyl 2-butenylphosphonate (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 ethylphosphonic 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);

[0233] phosphate esters such as (methyl)(2-propenyl)(2-propynyl)phosphate, (ethyl)(2-propenyl)(2-propynyl)phosphate, (2-butenyl)(methyl)(2-propynyl)phosphate, (2-butenyl)(ethyl)(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;

[0234] Among these, compounds having an alkynyloxy group are preferred because they form a more stable negative electrode coating in the electrolyte solution.

[0235] Furthermore, compounds such as 2-propynyl methyl 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 in terms of improving storage properties.

[0236] The compound having a triple bond may be used alone or in any combination and ratio of two or more. There is no limitation on the amount of the compound having a triple bond relative to the total composition of the present disclosure, and it may be any amount as long as it does not significantly impair the effects of the present disclosure. However, the compound is typically contained 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 typically 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, relative to the composition of the present disclosure. When the above range is satisfied, effects such as output characteristics, load characteristics, cycle characteristics, and high-temperature storage characteristics are further improved.

[0237] In the composition of the present disclosure, an overcharge inhibitor can be used to effectively prevent the battery from exploding or catching fire when an electrochemical device using the composition is overcharged or the like.

[0238] Examples of the overcharge inhibitor include unsubstituted or alkyl group-substituted terphenyl derivatives such as biphenyl, o-terphenyl, m-terphenyl, and p-terphenyl, partially hydrogenated unsubstituted or alkyl group-substituted terphenyl derivatives, aromatic compounds such as cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, cyclopentylbenzene, cyclohexylbenzene, cumene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, t-butylbenzene, t-amylbenzene, t-hexylbenzene, and anisole; and aromatic compounds such as 2-fluorobiphenyl, 4-fluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, and cyclohexyl benzene. Examples of the aromatic hydrocarbon derivative include partially fluorinated compounds of the above aromatic compounds such as xylfluorobenzene, fluorobenzene, fluorotoluene, and benzotrifluoride; fluorine-containing 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 group-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, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, diphenyl carbonate, and methylphenyl carbonate are preferred.These may be used alone or in combination of two or more. When two or more are used in combination, it is particularly preferred to use a combination of cyclohexylbenzene with t-butylbenzene or t-amylbenzene, or a combination of at least one selected from oxygen-free aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, and t-amylbenzene with at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran, in terms of the balance between overcharge prevention properties and high-temperature storage properties.

[0239] The composition of the present disclosure may further contain a compound (5) represented by general formula (5).

[0240] General formula (5): [ka] (In the formula, A a+ is a metal ion, a hydrogen ion, or an onium ion; a is an integer of 1 to 3, b is an integer of 1 to 3, p is b / a, n203 is an integer of 1 to 4, n201 is an integer of 0 to 8, n202 is 0 or 1, Z 201 is a transition metal, an element in group III, IV, or V of the periodic table. 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 (an alkylene group, a halogenated alkylene group, an arylene group, and a halogenated arylene group may have a substituent or a heteroatom in the structure, and when n202 is 1 and n203 is 2 to 4, n203 X 201 may be bonded to each other). L 201is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms (an alkylene group, a halogenated alkylene group, an arylene group, and a halogenated arylene group may have a substituent or a heteroatom in the structure, and when n201 is 2 to 8, n201 L 201 may be bonded to each other to form a ring) or -Z 203 Y 203 . Y 201 , Y 202 and Z 203 are independently O, S, and NY 204 , a hydrocarbon group or a fluorinated hydrocarbon group. Y 203 and Y 204 are each independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (the alkyl group, halogenated alkyl group, aryl group, and halogenated aryl group may have a substituent or a heteroatom in the structure, and Y 203 or Y 204 When there are a plurality of such groups, they may be bonded to form a ring.

[0241] A a+ Examples of the cations include a lithium ion, a sodium ion, a potassium ion, a magnesium ion, a calcium ion, a barium ion, a cesium ion, a silver ion, a zinc ion, a copper ion, a cobalt ion, an iron ion, a nickel ion, a manganese ion, a titanium ion, a lead ion, a chromium ion, a vanadium ion, a ruthenium ion, a yttrium ion, a lanthanoid ion, an actinoid ion, a tetrabutylammonium ion, a tetraethylammonium ion, a tetramethylammonium ion, a triethylmethylammonium ion, a triethylammonium ion, a pyridinium ion, an imidazolium ion, a hydrogen ion, a tetraethylphosphonium ion, a tetramethylphosphonium ion, a tetraphenylphosphonium ion, a triphenylsulfonium ion, and a triethylsulfonium ion.

[0242] When used for electrochemical devices, etc., a+ is preferably a lithium ion, a sodium ion, a magnesium ion, a tetraalkylammonium ion, or a hydrogen ion, and particularly preferably a lithium ion. a+ The cation valence a is an integer between 1 and 3. If it is greater than 3, the crystal lattice energy increases, making it difficult to dissolve in a solvent. Therefore, if solubility is required, a value of 1 is more preferable. The anion valence b is also 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 inevitably determined by the ratio of the valences of the two, b / a.

[0243] Next, the ligand portion of general formula (5) will be described. In this specification, Z in general formula (5) 201 The organic or inorganic moiety that is bonded to the ligand is called a ligand.

[0244] Z 201 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.

[0245] 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 groups and arylene groups may have a substituent or a heteroatom in their structure. Specifically, instead of hydrogen on the alkylene group or arylene group, a halogen atom, a linear or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group, an amide group, or a hydroxyl group may be substituted, or a structure in which nitrogen, sulfur, or oxygen is introduced instead of carbon on the alkylene or arylene may be used. Furthermore, when n202 is 1 and n203 is 2 to 4, n203 X 201may be bonded to each other. An example of such a ligand is ethylenediaminetetraacetic acid.

[0246] L 201 is a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or -Z 203 Y 203 (Z 203 , Y 203 The alkyl group and aryl group in this case are also represented by X 201 Similarly, the structure may have a substituent or a heteroatom, and when n201 is 2 to 8, n201 L 201 may be bonded to each other to form a ring. 201 As the anionic group, a fluorine atom or a cyano group is preferred. In the case of a fluorine atom, the solubility and dissociation degree of the salt of the anionic compound are improved, and as a result, the ionic conductivity is improved. In addition, the oxidation resistance is improved, and thus the occurrence of side reactions can be suppressed.

[0247] Y 201 , Y 202 and Z 203 are independent of each other, O, S, NY 204 , a hydrocarbon group or a fluorinated hydrocarbon group. 201 and Y 202 is O, S or NY 204 It is preferable that Y is O, and more preferable that Y is O. 201 and Y 202 by Z 201 Because of the bond with Z 201 The chelate structure is formed with . 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 when it is 0, the chelate ring becomes a five-membered ring, which is particularly preferable because it maximizes the chelate effect and increases stability. In this specification, a fluorinated hydrocarbon group is a group in which at least one hydrogen atom of a hydrocarbon group has been substituted with a fluorine atom.

[0248] Y 203 and Y 204 are each independently H, F, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms, and these alkyl groups and aryl groups may have a substituent or a heteroatom in their structure, and Y 203 or Y 204 When a plurality of groups are present, they may be bonded to form a ring.

[0249] Furthermore, the constant n203 related to the number of ligands described above is an integer of 1 to 4, preferably 1 or 2, and more preferably 2. Furthermore, the constant n201 related to the number of ligands described above is an integer of 0 to 8, preferably an integer of 0 to 4, and more preferably 0, 2, or 4. Furthermore, it is preferable that when n203 is 1, n201 is 2, and when n203 is 2, n201 is 0.

[0250] In the general formula (5), the alkyl group, halogenated alkyl group, aryl group, and halogenated aryl group include those having other functional groups such as a branch, a hydroxyl group, or an ether bond.

[0251] Compound (5) has the general formula: [ka] (In the formula, A a+ ,a,b,p,n201,Z 201 and L 201 is as defined above), or a compound represented by the general formula: [ka] (In the formula, A a+ ,a,b,p,n201,Z 201 and L 201is as described above).

[0252] Compound (5) includes lithium oxalatoborate salts, and is represented by the following formula: [ka] Lithium bis(oxalato)borate (LIBOB), represented by the formula: [ka] Lithium difluorooxalatoborate (LIDFOB) represented by the formula: [ka] Lithium difluorooxalatophosphanite (LIDFOP) represented by the following formula: [ka] Lithium tetrafluorooxalatophosphanite (LITFOP) represented by the following formula: [ka] Examples of suitable fluorophosphanite include lithium bis(oxalato)difluorophosphanite represented by the following formula:

[0253] Compound (5) also includes dicarboxylic acid complex salts in which the central element of the complex is boron, such as lithium bis(malonato)borate, lithium difluoro(malonato)borate, lithium bis(methylmalonato)borate, lithium difluoro(methylmalonato)borate, lithium bis(dimethylmalonato)borate, and lithium difluoro(dimethylmalonato)borate.

[0254] Compound (5) also includes dicarboxylic acid complex salts in which the central element of the complex is phosphorus, such as lithium tris(oxalato)phosphate, lithium tris(malonato)phosphate, lithium difluorobis(malonato)phosphate, lithium tetrafluoro(malonato)phosphate, lithium tris(methylmalonato)phosphate, lithium difluorobis(methylmalonato)phosphate, lithium tetrafluoro(methylmalonato)phosphate, lithium tris(dimethylmalonato)phosphate, lithium difluorobis(dimethylmalonato)phosphate, and lithium tetrafluoro(dimethylmalonato)phosphate.

[0255] Compound (5) also includes dicarboxylic acid complex salts in which the central element of the complex is aluminum, such as LiAl(C2O4)2 and LiAlF2(C2O4).

[0256] Among these, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate are more preferably used because of their ease of availability and their ability to contribute to the formation of a stable coating structure. As the compound (5), lithium bis(oxalato)borate is particularly preferred.

[0257] The content of compound (5) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and is preferably 10% by mass or less, more preferably 3% by mass or less, relative to the solvent, since this provides even better cycle characteristics.

[0258] The composition used in the present disclosure may contain a carboxylic acid anhydride (excluding compound (2)). As the carboxylic acid anhydride, compound (6) represented by the following general formula (6) is preferred. The method for producing the carboxylic acid anhydride is not particularly limited, and it can be produced by any known method.

[0259] [ka] (In general formula (6), R 61 , R 62 each independently represents a hydrocarbon group having 1 to 15 carbon atoms, which may have a substituent.

[0260] R 61 , R 62 is not particularly limited in type as long as it is a monovalent hydrocarbon group. For example, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or may be a group in which an aliphatic hydrocarbon group and an aromatic hydrocarbon group are bonded. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain an unsaturated bond (a carbon-carbon double bond or a carbon-carbon triple bond). Furthermore, the aliphatic hydrocarbon group may be either chain-like or cyclic, and if it is chain-like, it may be linear or branched. Furthermore, it may be a group in which a chain-like group and a cyclic group are bonded. In addition, R 61 and R 62 may be the same as or different from each other.

[0261] Also, R 61 , R 62 When the hydrocarbon group has a substituent, the type of the substituent is not particularly limited as long as it does not contradict the spirit of the present disclosure, but examples include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms being preferred. Furthermore, examples of substituents other than halogen atoms include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, with cyano groups and carbonyl groups being preferred. 61 , R 62 The hydrocarbon group may have only one of these substituents or may have two or more of these substituents. When the hydrocarbon group has two or more substituents, the substituents may be the same or different from each other.

[0262] R 61 , R 62The number of carbon atoms in each hydrocarbon group of R 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 and R are bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms in the 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, the substituent is included in R 61 , R 62 It is preferable that the total number of carbon atoms falls within the above range.

[0263] Next, specific examples of the compound (6) will be described. In the following examples, the term "analog" refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure within the scope of the present disclosure, and examples thereof include a dimer, trimer, tetramer, etc. composed of multiple acid anhydrides, structural isomers such as those having the same number of carbon atoms in the substituent but having a branched chain, and those in which the substituent is bonded to the acid anhydride at a different position.

[0264] First, R 61 , R 62 Specific examples of acid anhydrides in which are the same are listed below.

[0265] R 61 , R 62 is a chain alkyl group, examples of which include 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 the like, as well as analogs thereof.

[0266] R61 , R 62 Specific examples of acid anhydrides in which is a cyclic alkyl group include cyclopropanecarboxylic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, and the like, and analogs thereof.

[0267] R 61 , R 62 is an alkenyl group, 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 anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-enoic anhydride, 2-methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentenecarboxylic anhydride, 3-cyclopentenecarboxylic anhydride, 4-cyclopentenecarboxylic anhydride, and the like, and analogs thereof.

[0268] R 61 , R 62 Specific examples of acid anhydrides in which is an alkynyl group include propynoic anhydride, 3-phenylpropynoic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride, 4-pentynoic anhydride, and analogs thereof.

[0269] R 61 , R 62 is an aryl group, include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 2-methylbenzoic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, 2-naphthalenecarboxylic anhydride, and analogs thereof.

[0270] Also, R 61 , R 62 As examples of acid anhydrides in which the halogen atoms are substituted, examples of acid anhydrides in which the halogen atoms are substituted mainly with fluorine atoms are given below, but 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 exemplified compounds.

[0271] R 61 , R 62 is a chain alkyl group substituted with a halogen atom, examples of which 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 analogs thereof.

[0272] R 61 , R 62 is a cyclic alkyl group substituted with a halogen atom, examples of which include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, 4-fluorocyclopentanecarboxylic anhydride, and analogs thereof.

[0273] R 61 , R 62Examples of acid anhydrides in which 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, 2-(4-fluoroacrylic anhydride), Examples of the fluorophenyl acrylic anhydride include 2-fluoro-3-butenoic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butenoic anhydride, 2,2-difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3,4-trifluoro-3-butenoic anhydride, and the like, as well as analogs thereof.

[0274] R 61 , R 62 is an alkynyl group substituted with a halogen atom, examples of which include 3-fluoro-2-propynoic anhydride, 3-(4-fluorophenyl)-2-propynoic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propynoic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride, 4,4,4-trifluoro-2-butynoic anhydride, and analogs thereof.

[0275] R 61 , R 62 Examples of acid anhydrides in which is an aryl group substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and the like, and analogs thereof.

[0276] R 61 , R 62Examples of acid anhydrides having a substituent with a functional group such as an ester, a nitrile, a ketone, or an ether include methoxyformic anhydride, ethoxyformic anhydride, methyloxalic anhydride, ethyloxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and the like, and their analogs.

[0277] Next, R 61 , R 62 Specific examples of acid anhydrides having different groups are listed below.

[0278] R 61 , R 62 Although all combinations of the above-mentioned examples and their analogues are conceivable, representative examples are given below.

[0279] Examples of combinations of chain alkyl groups include acetic acid propionic anhydride, acetic acid butanoic anhydride, butanoic acid propionic anhydride, and acetic acid 2-methylpropionic anhydride.

[0280] Examples of the combination of a chain alkyl group and a cyclic alkyl group include acetic acid cyclopentanoic anhydride, acetic acid cyclohexanoic anhydride, and cyclopentanoic acid propionic anhydride.

[0281] Examples of the combination of a chain alkyl group and an alkenyl group include acetic acid acrylic anhydride, acetic acid 3-methylacrylic anhydride, acetic acid 3-butenoic anhydride, and acrylic acid propionic anhydride.

[0282] Examples of the combination of a chain alkyl group and an alkynyl group include acetic acid propynoic anhydride, acetic acid 2-butynoic anhydride, acetic acid 3-butynoic anhydride, acetic acid 3-phenylpropynoic anhydride, and propionic acid propynoic anhydride.

[0283] Examples of the combination of a chain alkyl group and an aryl group include acetic acid benzoic anhydride, acetic acid 4-methylbenzoic anhydride, acetic acid 1-naphthalenecarboxylic anhydride, and benzoic acid propionic anhydride.

[0284] Examples of combinations of a chain alkyl group and a hydrocarbon group having a functional group include acetic acid fluoroacetic anhydride, acetic acid trifluoroacetic anhydride, acetic acid 4-fluorobenzoic anhydride, fluoroacetic acid propionic anhydride, acetic acid alkyl oxalic anhydride, acetic acid 2-cyanoacetic anhydride, acetic acid 2-oxopropionic anhydride, acetic acid methoxyacetic anhydride, and methoxyacetic acid propionic anhydride.

[0285] Examples of combinations of cyclic alkyl groups include cyclopentanoic acid and cyclohexanoic acid anhydride.

[0286] Examples of combinations of a cyclic alkyl group and an alkenyl group include acrylic acid cyclopentanoic anhydride, 3-methylacrylic acid cyclopentanoic anhydride, 3-butenoic acid cyclopentanoic anhydride, and acrylic acid cyclohexanoic anhydride.

[0287] Examples of the combination of a cyclic alkyl group and an alkynyl group include propynoic cyclopentanoic anhydride, 2-butynoic cyclopentanoic anhydride, and propynoic cyclohexanoic anhydride.

[0288] Examples of the combination of a cyclic alkyl group and an aryl group include benzoic acid cyclopentanoic acid anhydride, 4-methylbenzoic acid cyclopentanoic acid anhydride, and benzoic acid cyclohexanoic acid anhydride.

[0289] Examples of combinations of a cyclic alkyl group and a hydrocarbon group having a functional group include cyclopentanoic fluoroacetic anhydride, cyclopentanoic trifluoroacetic anhydride, cyclopentanoic 2-cyanoacetic anhydride, cyclopentanoic methoxyacetic anhydride, and cyclohexanoic fluoroacetic anhydride.

[0290] Examples of combinations of alkenyl groups include acrylic acid 2-methylacrylic anhydride, acrylic acid 3-methylacrylic anhydride, acrylic acid 3-butenoic anhydride, and 2-methylacrylic acid 3-methylacrylic anhydride.

[0291] Examples of the combination of an alkenyl group and an alkynyl group include acrylic acid propynoic anhydride, acrylic acid 2-butynoic anhydride, and 2-methylacrylic acid propynoic anhydride.

[0292] Examples of combinations of an alkenyl group and an aryl group include acrylic acid benzoic acid anhydride, acrylic acid 4-methylbenzoic acid anhydride, and 2-methylacrylic acid benzoic acid anhydride.

[0293] Examples of combinations of an alkenyl group and a hydrocarbon group having a functional group include acrylic fluoroacetic anhydride, acrylic trifluoroacetic anhydride, acrylic 2-cyanoacetic anhydride, acrylic methoxyacetic anhydride, and 2-methylacrylic fluoroacetic anhydride.

[0294] Examples of combinations of alkynyl groups include propynoic acid 2-butynoic acid anhydride, propynoic acid 3-butynoic acid anhydride, and 2-butynoic acid 3-butynoic acid anhydride.

[0295] Examples of a combination of an alkynyl group and an aryl group include benzoic acid propynoic anhydride, 4-methylbenzoic acid propynoic anhydride, and benzoic acid 2-butynoic anhydride.

[0296] Examples of the combination of an alkynyl group and a hydrocarbon group having a functional group include propynoic acid fluoroacetic anhydride, propynoic acid trifluoroacetic anhydride, propynoic acid 2-cyanoacetic anhydride, propynoic acid methoxyacetic anhydride, and 2-butynoic acid fluoroacetic anhydride.

[0297] Examples of combinations of aryl groups include benzoic acid 4-methylbenzoic acid anhydride, benzoic acid 1-naphthalenecarboxylic acid anhydride, and 4-methylbenzoic acid 1-naphthalenecarboxylic acid anhydride.

[0298] Examples of the combination of an aryl group and a hydrocarbon group having a functional group include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, and 4-methylbenzoic acid fluoroacetic anhydride.

[0299] Examples of combinations of hydrocarbon groups having functional groups include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, and trifluoroacetic acid 2-cyanoacetic anhydride.

[0300] Among the acid anhydrides forming the chain structure, preferred are acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, propynoic anhydride, 2-butynoic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3-trifluoroacetic anhydride, 2-methyl-3-butenoic ... Examples of the acrylic anhydride include fluoropropionic 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, and more preferably, 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.

[0301] These compounds are preferred from the viewpoint that they can appropriately form bonds with lithium oxalate salts to form coatings with excellent durability, thereby improving charge / discharge rate characteristics, input / output characteristics, and impedance characteristics, particularly after durability tests.

[0302] The molecular weight of the carboxylic acid anhydride is not limited and may be any value as long as it does not significantly impair the effects of the present disclosure, but is usually at least 90, preferably at least 95, and usually at most 300, preferably at most 200. When the molecular weight of the carboxylic acid anhydride is within the above range, an increase in the viscosity of the electrolyte can be suppressed, and the coating density can be optimized, thereby appropriately improving durability.

[0303] The method for producing the carboxylic acid anhydride is not particularly limited, and any known method can be selected for production. The nonaqueous electrolyte solution of the present disclosure may contain any one of the above-described carboxylic acid anhydrides alone, or may contain two or more of them in any combination and ratio.

[0304] The content of the carboxylic acid anhydride in the composition of the present disclosure is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but it is desirable to include it in 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, relative to the composition of the present disclosure. When the content of the carboxylic acid anhydride is within the above range, the effect of improving cycle characteristics is easily exhibited, and the reactivity is suitable, so that battery characteristics are easily improved.

[0305] Other known coagents may be used in the composition of the present disclosure, such as 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 erythritan carbonate, spiro-bis-dimethylene carbonate, and methoxyethyl-methyl carbonate; Ether compounds such as dioxolane, dioxane, 2,5,8,11-tetraoxadodecane, 2,5,8,11,14-pentaoxapentadecane, 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, ethyl methyl 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-diyl diformate, 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 sultone, butylene sulfite, butane-2,3-diyldimethanesulfonate, 2-butyne-1,4-diyldimethanesulfonate, 2-propynyl vinylsulfonate, bis(2-vinylsulfonylethyl) ether, 5-vinyl-hexahydro-1,3,2-benzodioxathiol-2-oxide, 2-propynyl 2-(methanesulfonyloxy)propionate, 5,5-dimethyl-1,2-oxathiolan-4-one 2,2-dioxy sulfur-containing compounds such as 3-sulfo-propionic anhydride, trimethylenemethane disulfonate, 2-methyltetrahydrofuran, trimethylenemethane disulfonate, tetramethylene sulfoxide, dimethylenemethane disulfonate, difluoroethyl methyl sulfone, divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, ethylenebismethyl sulfonate, ethylenebisethyl sulfonate, 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 phosphite, triethyl phosphite, triphenyl phosphite, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl vinylphosphonate, diethyl vinylphosphonate, ethyl diethylphosphonoacetate, methyl dimethylphosphinate, ethyl diethylphosphinate, trimethylphosphine oxide, triethylphosphine oxide, bis(2,2-difluoroethyl) 2,2,2-trifluoroethyl phosphate, bis(2,2,3,3-tetrafluoroethyl) phosphate Bis(2,2,2-trifluoroethyl) 2,2,2-trifluoroethyl phosphate, 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 phosphate, tributyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, tris(1,1,1,3,3,3-hexafluoropropan-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) phosphite, tris(triethylsilyl) phosphite, tris(trimethoxysilyl) phosphite, and trimethylsilyl polyphosphate; Boron-containing compounds such as tris(trimethylsilyl) borate and tris(trimethoxysilyl) borate; silane compounds such as dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titanium tetrakis(trimethylsiloxide), titanium tetrakis(triethylsiloxide), and tetramethylsilane; These may be used alone or in combination of two or more. By adding these auxiliary agents, it is possible to improve the capacity retention characteristics and cycle characteristics after high-temperature storage. Of the other auxiliaries, phosphorus-containing compounds are preferred, and tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite are preferred.

[0306] The amount of the other auxiliary agents is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present disclosure. The amount of the other auxiliary agents is preferably 0.01% by mass or more and 5% by mass or less, based on 100% by mass of the composition. Within this range, the effects of the other auxiliary agents are easily exerted and deterioration of battery characteristics such as high-load discharge characteristics is easily avoided. The amount of the other auxiliary agents is more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and more preferably 3% by mass or less, even more preferably 1% by mass or less.

[0307] The composition of the present disclosure may further contain additives such as cyclic and chain carboxylic acid esters, ether compounds, nitrogen-containing compounds, boron-containing compounds, organosilicon-containing compounds, non-flammable (flame retardant) agents, surfactants, high-dielectric additives, cycle performance and rate performance improvers, and sulfone-based compounds, within the scope that does not impair the effects of the present disclosure.

[0308] Examples of the cyclic carboxylic acid ester include those having a total carbon atom number of 3 to 12 in the structural formula. Specific examples include gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, epsilon-caprolactone, 3-methyl-γ-butyrolactone, etc. Among these, gamma-butyrolactone is particularly preferred from the viewpoint of improving the characteristics of electrochemical devices due to an improved degree of lithium ion dissociation.

[0309] The amount of the cyclic carboxylic acid ester blended as an additive is typically preferably 0.1% by mass or more, more preferably 1% by mass or more, based on 100% by mass of the solvent. This range improves the electrical conductivity of the composition and facilitates the enhancement of the large-current discharge characteristics of the electrochemical device. Furthermore, the amount of the cyclic carboxylic acid ester blended is preferably 10% by mass or less, more preferably 5% by mass or less. By setting the upper limit in this way, the viscosity of the electrolyte solution is kept within an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and the large-current discharge characteristics of the electrochemical device are more likely to be within a favorable range.

[0310] Furthermore, as the cyclic carboxylic acid ester, a fluorinated cyclic carboxylic acid ester (fluorine-containing lactone) can also be suitably used. Examples of the fluorine-containing lactone include those represented by the following formula (C):

[0311] [ka]

[0312] (In the formula, X 15 ~X 20 are the same or different and are each -H, -F, -Cl, -CH3, or a fluorinated alkyl group; provided that X 15 ~X 20 at least one of which is a fluorinated alkyl group Examples of fluorine-containing lactones include those represented by the following formula:

[0313] X 15 ~X 20Examples of the fluorinated alkyl group in include -CFH2, -CF2H, -CF3, -CH2CF3, -CF2CF3, -CH2CF2CF3, -CF(CF3)2, and the like, with -CH2CF3 and -CH2CF2CF3 being preferred due to their high oxidation resistance and safety-improving effect.

[0314] X 15 ~X 20 is a fluorinated alkyl group, -H, -F, -Cl, -CH3 or a fluorinated alkyl group is 15 ~X 20 The substitution may be at only one position or at multiple positions, preferably 1 to 3 positions, more preferably 1 to 2 positions, in view of good solubility of the electrolyte salt.

[0315] The substitution position of the fluorinated alkyl group is not particularly limited, but X is preferred because it provides a good synthesis yield. 17 and / or X 18 But especially X 17 or X 18 is preferably a fluorinated alkyl group, particularly -CH2CF3 or -CH2CF2CF3. X other than a fluorinated alkyl group 15 ~X 20 is -H, -F, -Cl or CH3, and is preferably -H in view of good solubility of the electrolyte salt.

[0316] In addition to those represented by the above formula, the fluorine-containing lactones include, for example, those represented by the following formula (D):

[0317] [ka]

[0318] (In the formula, either A or B is CX 226 X 227 (X 226 and X 227are the same or different, and each is -H, -F, -Cl, -CF3, -CH3, or an alkylene group in which a hydrogen atom may be replaced by a halogen atom and which may contain a heteroatom in the chain), and the other is an oxygen atom; Rf 12 is a fluorinated alkyl group or a fluorinated alkoxy group which may have an ether bond; X 221 and X 222 are the same or different and are each -H, -F, -Cl, -CF3 or -CH3; X 223 ~X 225 are the same or different, and each represents an alkyl group in which a hydrogen atom may be replaced by -H, -F, -Cl, or a halogen atom and which may contain a heteroatom in the chain; n=0 or 1). Also included are fluorine-containing lactones represented by the following formula:

[0319] The fluorine-containing lactone represented by formula (D) includes a fluorine-containing lactone represented by the following formula (E):

[0320] [ka]

[0321] (In the formula, A, B, Rf 12 , X 221 , X 222 and X 223 is the same as formula (D) A five-membered ring structure represented by the following formula (F):

[0322] [ka]

[0323] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 is the same as formula (D) and a fluorine-containing lactone represented by the following formula (G):

[0324] [ka]

[0325] (In the formula, Rf 12 , X 221 , X 222 , X 223 , X 226 and X 227 is the same as formula (D) There is a fluorine-containing lactone represented by the formula:

[0326] Among these, the electrolyte solution of the present disclosure is particularly advantageous in that it can exhibit excellent properties such as a high dielectric constant and a high withstand voltage, and also in that it has good solubility of the electrolyte salt and good reduction in internal resistance, thereby improving the properties of the electrolyte solution of the present disclosure.

[0327] [ka] etc. By incorporating a fluorinated cyclic carboxylic acid ester, effects such as improved ionic conductivity, improved safety, and improved stability at high temperatures can be obtained.

[0328] Examples of the chain carboxylic acid ester include those having a total carbon number in the structural formula of 3 to 7. Specific 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.

[0329] Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. are preferred from the viewpoint of improving ionic conductivity due to reduced viscosity.

[0330] The ether compound is preferably a chain ether having 2 to 10 carbon atoms or a cyclic ether having 3 to 6 carbon atoms. Examples of chain 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.

[0331] 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 fluorinated compounds thereof. 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 in terms of their high solvation ability for lithium ions and improved ionic dissociation, and dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferred because they have low viscosity and provide high ionic conductivity.

[0332] As the ether compound, fluorinated ethers other than the fluorinated ether (E) can also be suitably used.

[0333] Examples of the nitrogen-containing compound include nitriles, fluorine-containing nitriles, carboxylic acid amides, fluorine-containing carboxylic acid amides, sulfonic acid amides, fluorine-containing sulfonic acid amides, acetamide, and formamide. Also usable are 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxaziridinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide. However, the nitrile compounds represented by the general formulas (1a), (1b), and (1c) are not included in the nitrogen-containing compound.

[0334] Examples of the boron-containing compound include boric acid esters such as trimethyl borate and triethyl borate, boric acid ethers, and alkyl borates.

[0335] Examples of the organic silicon-containing compound include (CH3)4-Si, (CH3)3-Si-Si(CH3)3, and silicone oil.

[0336] Examples of the flame retardant (flame retardant) agent include phosphate esters and phosphazene compounds. Examples of the phosphate esters include fluorine-containing alkyl phosphate esters, non-fluorine-containing alkyl phosphate esters, and aryl phosphate esters. Among these, fluorine-containing alkyl phosphate esters are preferred because they can exert a flame retardant effect even in small amounts.

[0337] Examples of the phosphazene compound include methoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, dimethylaminopentafluorocyclotriphosphazene, diethylaminopentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0338] Specific examples of the fluorine-containing alkyl phosphate ester include the fluorine-containing dialkyl phosphate ester described in JP-A-11-233141, the cyclic alkyl phosphate ester described in JP-A-11-283669, and the fluorine-containing trialkyl phosphate ester.

[0339] As the non-combustible (flame retardant) agent, (CH3O)3P=O, (CF3CH2O)3P=O, (HCF2CH2O)3P=O, (CF3CF2CH2)3P=O, (HCF2CF2CH2)3P=O, and the like are preferred.

[0340] The surfactant may be any of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant, but is preferably one containing a fluorine atom in terms of improving cycle characteristics and rate characteristics.

[0341] Such a surfactant containing a fluorine atom is, for example, a surfactant represented by the following formula (40): Rf 6 SO3 - M + (40) (In the formula, Rf 6 is a fluorine-containing alkyl group having 3 to 10 carbon atoms which may contain an ether bond; M + Li + , Na + , K. + or NHR'3 + (R' may be the same or different and both are H or alkyl groups having 1 to 3 carbon atoms) Preferred are fluorine-containing sulfonates represented by the following formula:

[0342] The content of the surfactant in the electrolyte is preferably 0.01 to 2% by mass, since it is possible to reduce the surface tension of the electrolyte without reducing the charge-discharge cycle characteristics.

[0343] Examples of the high-dielectric additive include sulfolane, methylsulfolane, γ-butyrolactone, and γ-valerolactone.

[0344] Examples of the cycle performance and rate performance improver include methyl acetate, ethyl acetate, tetrahydrofuran, and 1,4-dioxane.

[0345] Furthermore, the composition of the present disclosure may be further combined with a polymer material to form a gel-like (plasticized) gel electrolyte solution.

[0346] Examples of such polymer materials include conventionally known polyethylene oxide, polypropylene oxide, and modified products thereof (see Japanese Patent Application Laid-Open Nos. 8-222270 and 2002-100405); polyacrylate polymers, polyacrylonitrile, fluororesins such as polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers (see Japanese Patent Application Laid-Open Nos. 4-506726, 8-507407, and 10-294131); and composites of such fluororesins with hydrocarbon resins (see Japanese Patent Application Laid-Open Nos. 11-35765 and 11-86630). In particular, polyvinylidene fluoride and vinylidene fluoride-hexafluoropropylene copolymers are preferably used as polymer materials for gel electrolytes.

[0347] In addition, the composition of the present disclosure may also contain an ion-conductive compound described in Japanese Patent Application No. 2004-301934.

[0348] The ion-conducting compound has the formula (101): A-(D)-B (101) [Wherein D is a group represented by formula (201): -(D1) n -(FAE) m -(AE) p -(Y) q - (201) (Wherein D1 is a compound represented by formula (2a):

[0349] [ka]

[0350] (wherein Rf represents a fluorine-containing ether group which may have a crosslinkable functional group; R 10 is a group or bond connecting Rf to the main chain) an ether unit having a fluorine-containing ether group in the side chain, represented by the formula: FAE is expressed by the formula (2b):

[0351] [ka]

[0352] (wherein Rfa represents a hydrogen atom or a fluorinated alkyl group which may have a crosslinkable functional group; R 11 is the group or bond connecting Rfa to the main chain) an ether unit having a fluorinated alkyl group in the side chain, represented by the formula: AE is represented by the formula (2c):

[0353] [ka]

[0354] (In the formula, R 13 represents 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; R 12 is R 13 and the main chain) Ether units denoted by ; Y is expressed by the formulas (2d-1) to (2d-3):

[0355] [ka]

[0356] 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 10,000; q is an integer from 1 to 100; provided that n+m is not 0, and the bonding order of D1, FAE, AE, and Y is not specified); A and B may be the same or different and are each a hydrogen atom, an alkyl group which may contain a fluorine atom and / or a crosslinkable functional group, a phenyl group which may contain a fluorine atom and / or a crosslinkable functional group, a -COOH group, -OR (R is a hydrogen atom or an alkyl group which may contain a fluorine atom and / or a crosslinkable functional group), an ester group, or a carbonate group (however, when the terminal of D is an oxygen atom, it is not a -COOH group, -OR, ester group, or carbonate group) The compound is an amorphous fluorine-containing polyether compound having a fluorine-containing group in the side chain, represented by the formula:

[0357] The composition of the present disclosure may contain a sulfone-based compound. As the sulfone-based compound, cyclic sulfones having 3 to 6 carbon atoms and chain sulfones having 2 to 6 carbon atoms are preferred. The number of sulfonyl groups in one molecule is preferably 1 or 2.

[0358] 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, from the viewpoints of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0359] The sulfolanes are preferably sulfolane and / or sulfolane derivatives (hereinafter, sulfolane may also be abbreviated as "sulfolanes"). The sulfolane derivatives are preferably those in which one or more hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group.

[0360] 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, and the like are preferred because they have high ionic conductivity and high input / output.

[0361] Examples of chain 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 thereof include fluoromethyl-n-propyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, and pentafluoroethyl-t-butyl sulfone.

[0362] 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, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, trifluoromethyl-t-butyl sulfone, and the like are preferred because of their high ionic conductivity and high input / output.

[0363] The content of the sulfone-based compound is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but is usually 0.3 vol% or more, preferably 0.5 vol% or more, more preferably 1 vol% or more, and usually 40 vol% or less, preferably 35 vol% or less, more preferably 30 vol% or less, based on 100 vol% of the solvent. If the content of the sulfone-based compound is within the above range, it is easy to obtain an effect of improving durability such as cycle characteristics and storage characteristics, and it is also possible to keep the viscosity of the nonaqueous electrolyte solution within an appropriate range, avoid a decrease in electrical conductivity, and keep the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery within appropriate ranges.

[0364] From the viewpoint of improving output characteristics, the composition of the present disclosure also preferably contains, as an additive, at least one compound (7) selected from the group consisting of lithium fluorophosphate salts (excluding LiPF) and lithium salts having an S=O group. When compound (7) is used as an additive, it is preferable to use a compound other than compound (7) as the electrolyte salt.

[0365] Examples of the lithium fluorophosphate salts include lithium monofluorophosphate (LiPO3F) and lithium difluorophosphate (LiPO2F2). Examples of the lithium salts having the S=O group include lithium monofluorosulfonate (FSO3Li), lithium methylsulfate (CH3OSO3Li), lithium ethylsulfate (C2H5OSO3Li), and lithium 2,2,2-trifluoroethylsulfate. Of these, LiPO2F2, FSO3Li, and C2H5OSO3Li are preferred as compound (7).

[0366] The content of compound (7) in the composition 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.

[0367] The composition of the present disclosure may further contain other additives as needed, such as metal oxides and glass.

[0368] The composition of the present disclosure preferably contains at least one additive selected from the group consisting of unsaturated cyclic carbonates, compound (2), nitrile compounds, fluorinated saturated cyclic carbonates, lithium salts having an S=O group, lithium imide salts, lithium fluorophosphate salts (excluding LiPF6), and compound (5). By including these additives, the increase in resistance during high-temperature storage can be further suppressed. The additive is preferably at least one selected from the group consisting of unsaturated cyclic carbonates, compound (4), nitrile compounds represented by general formula (1a), fluorinated saturated cyclic carbonates, lithium sulfonate compounds, LiN(FSO2)2, lithium difluorophosphate (LiPO2F2), lithium bis(oxalato)borate (LIBOB), and lithium difluorooxalatoborate (LIDFOB); More preferably, it is at least one selected from the group consisting of vinylene carbonate, vinylethylene carbonate, maleic anhydride, adiponitrile, fluoroethylene carbonate, FSO3Li, LiN(FSO2)2, LiPO2F2, LIBOB, and LIDFOB.

[0369] The composition of the present disclosure preferably contains 1 to 1000 ppm of hydrogen fluoride (HF). The inclusion of HF can promote the film formation of the above-mentioned additives. If the HF content is too low, the film formation ability on the negative electrode decreases, and the electrochemical device performance tends to deteriorate. If the HF content is too high, the oxidation resistance of the electrolyte tends to decrease due to the influence of HF. The composition of the present disclosure, even if it contains HF within the above range, does not decrease the high-temperature storage recovered capacity rate of the electrochemical device. 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.

[0370] The compositions of the present disclosure may be prepared by any method using the ingredients described above.

[0371] The composition of the present disclosure can be suitably applied to, for example, electrochemical devices such as secondary batteries such as lithium ion secondary batteries, lithium ion capacitors, hybrid capacitors, electric double layer capacitors, etc. Hereinafter, a nonaqueous electrolyte battery using the composition of the present disclosure will be described. The nonaqueous electrolyte battery can have a known structure and typically includes a positive electrode and a negative electrode capable of absorbing and desorbing ions (e.g., lithium ions) and the composition (electrolyte) of the present disclosure. An electrochemical device including such a composition (electrolyte) of the present disclosure also constitutes the present disclosure.

[0372] Examples of electrochemical devices include secondary batteries such as lithium ion secondary batteries, lithium ion capacitors, capacitors (hybrid capacitors and electric double layer capacitors), radical batteries, solar cells (particularly dye-sensitized solar cells), lithium ion primary batteries, fuel cells, various electrochemical sensors, electrochromic elements, electrochemical switching elements, aluminum electrolytic capacitors, and tantalum electrolytic capacitors, with secondary batteries such as lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors being preferred. The present disclosure also includes a module including the electrochemical device.

[0373] The present disclosure also relates to a secondary battery comprising the composition (electrolyte) of the present disclosure. The secondary battery preferably comprises a positive electrode, a negative electrode, and the above-mentioned electrolyte solution. The secondary battery is preferably a lithium ion secondary battery.

[0374] <Positive electrode> The positive electrode is composed of a positive electrode active material layer containing a positive electrode active material and a current collector.

[0375] The positive electrode active material is not particularly limited as long as it can electrochemically absorb and release lithium ions, and examples thereof include lithium-containing transition metal composite oxides, lithium-containing transition metal phosphate compounds, sulfur-based materials, conductive polymers, etc. Among these, lithium-containing transition metal composite oxides and lithium-containing transition metal phosphate compounds are preferred as the positive electrode active material, and lithium-containing transition metal composite oxides that generate high voltage are particularly preferred.

[0376] The transition metal of the lithium-containing transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples include lithium-cobalt composite oxides such as LiCoO2, lithium-nickel composite oxides such as LiNiO2, lithium-manganese composite oxides such as LiMnO2, LiMn2O4, and Li2MnO4, and those in which some of the transition metal atoms that make up the main part of these lithium transition metal composite oxides have been 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. Specific examples of substituted oxides include LiNi 0.5 Mn 0.5 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.45 Co 0.10 Al 0.45 O2, LiMn 1.8 Al 0.2 O4, LiMn 1.5 Ni 0.5 Examples include O4.

[0377] Among these, the lithium-containing transition metal composite oxide is LiMn, which has a high energy density even when applied at high voltage. 1.5 Ni 0.5 O4, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 is preferred. Among them, LiMn is preferred for high voltages of 4.4V or more. 1.5 Ni 0.5 O4 is preferred.

[0378] Among these, the lithium-containing transition metal composite oxide is LiNi because it can provide a high-capacity lithium ion secondary battery. 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.85 Co 0.10 Al 0.05 O2 is preferred.

[0379] The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, cobalt phosphates such as LiCoPO4, and lithium transition metal phosphate compounds in which a portion of the transition metal atoms that constitute the main components of these compounds have been substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.

[0380] Examples of the lithium-containing transition metal composite oxide include: Formula: Li a Mn 2-b M 1 b O4 (in the formula, 0.9≦a;0≦b≦1.5;M 1 and wherein the metal is 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:LiNi 1-c M 2 c O2 (where 0≦c≦0.5;M 2 is 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:LiCo 1-d M 3d O2 (where 0 ≦ d ≦ 0.5; M 3 is 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). Examples thereof include lithium-cobalt composite oxides represented by the formula.

[0381] Among them, LiCoO2, LiMnO2, LiNiO2, LiMn2O4, LiNi 0.8 Co 0.15 Al 0.05 O2, or LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 are preferred because they can provide a lithium-ion secondary battery with high energy density and high output.

[0382] Other examples of the above-described positive electrode active materials include LiFePO4, LiNi 0.8 Co 0.2 O2, Li 1.2 Fe 0.4 Mn 0.4 O2, LiNi 0.5 Mn 0.5 O2, LiV3O6, Li2MnO3, and the like.

[0383] Examples of the above-described sulfur-based materials include materials containing sulfur atoms, and at least one selected from the group consisting of elemental sulfur, metal sulfides, and organic sulfur compounds is preferred, and elemental sulfur is more preferred. The above metal sulfide may be a metal polysulfide. The above organic sulfur compound may be an organic polysulfide.

[0384] Examples of the above metal sulfides include compounds represented by LiS x (0 < x ≦ 8); compounds represented by Li2S x (0 < x ≦ 8); compounds having a two-dimensional layered structure such as TiS2 and MoS2; Chevrel compounds having a strong three-dimensional skeleton structure represented by the general formula Me x Mo6S8 (Me is various transition metals including Pb, Ag, and Cu), and the like.

[0385] The organic sulfur compounds include carbon sulfide compounds.

[0386] The organic sulfur compound may be supported on a porous material such as carbon and used as a carbon composite material. The sulfur content in the carbon composite material is preferably 10 to 99% by mass, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, and preferably 85% by mass or less, to provide better cycle performance and further reduce overvoltage. When the positive electrode active material is the elemental sulfur, the content of sulfur contained in the positive electrode active material is equal to the content of the elemental sulfur.

[0387] Examples of conductive polymers include p-doped conductive polymers and n-doped conductive polymers, as well as polyacetylenes, polyphenylenes, heterocyclic polymers, ionic polymers, ladder and network polymers, etc.

[0388] Furthermore, it is preferable to include lithium phosphate in the positive electrode active material, since this improves continuous charging characteristics. Although there are no limitations on the use of lithium phosphate, it is preferable to use a mixture of the positive electrode active material and lithium phosphate. The amount of lithium phosphate used, based on the total of the positive electrode active material and lithium phosphate, is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

[0389] Alternatively, a substance having a different composition may be attached to the surface of the positive electrode active material, such as an oxide, such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, or bismuth oxide; a sulfate, such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, or aluminum sulfate; a carbonate, such as lithium carbonate, calcium carbonate, or magnesium carbonate; or carbon.

[0390] These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending the substance in a solvent, impregnating the positive electrode active material, and then drying, a method of dissolving or suspending a surface-attaching substance precursor in a solvent, impregnating the positive electrode active material, and then reacting the surface-attaching substance by heating, or a method of adding the substance to a positive electrode active material precursor and simultaneously calcining the surface-attaching substance, etc. When carbon is attached, a method of mechanically attaching the carbonaceous material in the form of, for example, activated carbon, etc., after the surface-attaching substance is attached can also be used.

[0391] The amount of the surface-attached substance is, by mass relative to the positive electrode active material, preferably 0.1 ppm or more as the lower limit, more preferably 1 ppm or more, and even more preferably 10 ppm or more, and preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less as the upper limit. The surface-attached substance can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material and improve the battery life, but if the amount of attachment is too small, the effect will not be fully exerted, and if it is too large, the movement of lithium ions will be hindered, which may increase the resistance.

[0392] The shape of the particles of the positive electrode active material may be any of the conventional shapes such as block, polyhedron, sphere, oval sphere, plate, needle, column, etc. Furthermore, primary particles may aggregate to form secondary particles.

[0393] The tap density of the positive electrode active material is usually 1.5 g / cm 3 or more, preferably 2.0 g / cm 3 More preferably, 2.5 g / cm 3or more, most preferably 3.0 g / cm 3 That's all. If the tap density of the positive electrode active material is below the lower limit, the amount of dispersion medium required when forming the positive electrode active material layer increases, and the amounts of conductive material and binder required also increase, which may restrict the filling rate of the positive electrode active material in the positive electrode active material layer and limit the battery capacity. By using a metal composite oxide powder with a high tap density, a high-density positive electrode active material layer can be formed. Generally, the higher the tap density, the better, and there is no particular upper limit, but it is usually 4.5 g / cm 3 or less, preferably 4.3 g / cm 3 The following is the result. In the present disclosure, the tap density is the powder packing density (tap density) g / cm when 5 to 10 g of positive electrode active material powder is placed in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of approximately 20 mm. 3 is required.

[0394] The median diameter d50 of the positive electrode active material particles (the secondary particle diameter when 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, and is 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. Below the lower limit, a high tap density product may not be obtained. Above the upper limit, lithium diffusion within the particles takes too long, resulting in reduced battery performance and problems such as streaking during battery positive electrode preparation, i.e., when the active material, conductive material, binder, etc. are slurried with a solvent and applied as a thin film. Mixing two or more of the above positive electrode active materials with different median diameters d50 can further improve the packing properties during positive electrode preparation.

[0395] In the present disclosure, the median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using a HORIBA LA-920 as the particle size distribution analyzer, the measurement is performed using a 0.1% by mass aqueous solution of sodium hexametaphosphate as the dispersion medium, and after ultrasonic dispersion for 5 minutes, the measurement is performed with a refractive index set to 1.24.

[0396] 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, with an upper limit of 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. If the upper limit is exceeded, it becomes difficult to form spherical secondary particles, which can adversely affect powder packing and significantly reduce the specific surface area, potentially resulting in a decrease in battery performance, such as output characteristics. Conversely, if the lower limit is exceeded, problems such as poor charge / discharge reversibility can occur due to underdeveloped crystals.

[0397] In the present disclosure, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at 10,000x magnification, the longest intercept value of a horizontal line at the left and right boundary lines of a primary particle is determined for any 50 primary particles, and the average value is calculated.

[0398] The BET specific surface area of ​​the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2m 2 / g or more, more preferably 0.3m 2 / 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 If the BET specific surface area is smaller than this range, the battery performance is likely to decrease, whereas if it is larger, it becomes difficult to increase the tap density, which may easily cause problems with the coating properties when forming the positive electrode active material layer.

[0399] In the present disclosure, the BET specific surface area is defined as a value measured by a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.) using a nitrogen-helium mixed gas precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3, after which the sample is pre-dried at 150°C for 30 minutes under a nitrogen flow, by a nitrogen adsorption BET single-point method using a gas flow method.

[0400] When the secondary battery of the present disclosure is used as a large-scale lithium-ion secondary battery for hybrid vehicles or distributed power sources, high output is required, and therefore it is preferable that the particles of the positive electrode active material are mainly secondary particles. The particles of the positive electrode active material preferably contain 0.5 to 7.0 volume % of fine particles having an average secondary particle size of 40 μm or less and an average primary particle size of 1 μm or less. By including fine particles having an average primary particle size of 1 μm or less, the contact area with the electrolyte increases, which allows for faster diffusion of lithium ions between the electrode and the electrolyte, thereby improving the output performance of the battery.

[0401] The cathode active material is produced by a method generally used for producing inorganic compounds. In particular, various methods can be considered for producing spherical or oval-spherical active materials, such as dissolving or pulverizing and dispersing raw materials of transition metals in a solvent such as water, adjusting the pH while stirring, producing and recovering spherical precursors, drying them as necessary, and then adding a Li source such as LiOH, Li2CO3, or LiNO3 and baking them at a high temperature to obtain the active material.

[0402] For the production of a positive electrode, the above-mentioned positive electrode active materials may be used alone, or two or more of different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 Examples of such a material include a combination of LiMn2O4 such as O2 or a combination of LiCoO ...

[0403] The content of the positive electrode active material is preferably 50 to 99.5% by mass of the positive electrode mixture, more preferably 80 to 99% by mass, in terms of high battery capacity. 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, more preferably 98% by mass or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electrical capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

[0404] The positive electrode mixture preferably further contains a binder, a thickener, and a conductive material. Any material can be used as the binder as long as it is safe for the solvents and electrolytes used in the production of electrodes. Examples of such binders include resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, chitosan, alginic acid, polyacrylic acid, polyimide, cellulose, and nitrocellulose; rubber-like polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; styrene-butadiene-styrene block copolymers or hydrogenated products thereof; and EPDM (ethylene-propylene diene polymer). Examples of suitable polymers include thermoplastic elastomeric polymers such as styrene-ethylene-butadiene-styrene terpolymers, styrene-ethylene-butadiene-styrene copolymers, styrene-isoprene-styrene block copolymers, and hydrogenated products thereof; soft resinous polymers such as syndiotactic 1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymers, and propylene-α-olefin copolymers; fluorinated polymers such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride copolymers, and tetrafluoroethylene-ethylene copolymers; and polymer compositions with ionic conductivity for alkali metal ions (especially lithium ions). These may be used alone or in any combination and ratio of two or more.

[0405] The content of the binder, expressed as the proportion of the binder in 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 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, and most preferably 10% by mass or less. If the proportion of the binder is too low, the positive electrode active material cannot be sufficiently held, resulting in insufficient mechanical strength of the positive electrode and possibly deteriorating battery performance such as cycle characteristics. On the other hand, if the proportion is too high, it may lead to a decrease in battery capacity and conductivity.

[0406] Examples of the thickener include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphated starch, casein, polyvinylpyrrolidone, and salts thereof. One type may be used alone, or two or more types may be used in any combination and ratio.

[0407] 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 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. If the ratio is below this range, the coating properties may be significantly reduced. If the ratio is above this range, the ratio of the active material in the positive electrode active material layer may decrease, which may cause problems such as a decrease in battery capacity or an increase in resistance between the positive electrode active materials.

[0408] Any known conductive material can be used as the conductive material. Specific examples include metal materials such as copper, nickel, and gold; graphite (e.g., natural graphite and artificial graphite); carbon black (e.g., acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black); and carbon materials such as needle coke, carbon nanotubes, fullerenes, and amorphous carbon (e.g., VGCF). These materials may be used alone or in any combination and ratio of two or more. The conductive material is typically present in the positive electrode active material layer in an amount of at least 0.01% by mass, preferably at least 0.1% by mass, and more preferably at least 1% by mass, and typically at most 50% by mass, preferably at most 30% by mass, and more preferably at most 15% by mass. A content below this range may result in insufficient conductivity. Conversely, a content above this range may result in a decrease in battery capacity.

[0409] The solvent for forming the slurry is not particularly limited as long as it can dissolve or disperse the positive electrode active material, conductive material, binder, and thickener used as needed, and 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 hexamethylphosphalamide and dimethyl sulfoxide.

[0410] Examples of materials for the positive electrode current collector include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or alloys thereof; and carbon materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum or its alloys, are preferred.

[0411] Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal for metal materials, and carbon plate, carbon thin film, and carbon cylinder for carbon materials. Of these, metal thin films are preferred. The thin film may be formed into a mesh shape as appropriate. The thickness of the thin film is optional, but is usually 1 μm or more, preferably 3 μm or more, and 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, the strength required as a current collector may be insufficient. Conversely, if the thin film is thicker than this range, handling may be impaired.

[0412] In addition, it is also preferable that the surface of the current collector is coated with a conductive additive, from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive additive include carbon and precious metals such as gold, platinum, and silver.

[0413] The thickness ratio of the current collector to 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 the electrolyte is poured) / (thickness of the current collector) is preferably 20 or less, more preferably 15 or less, and most preferably 10 or less, and is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. If the ratio exceeds this range, the current collector may generate heat due to Joule heat during high current density charge / discharge. If the ratio is below this range, the volume ratio of the current collector to the positive electrode active material increases, which may reduce the battery capacity.

[0414] The positive electrode may be manufactured by a conventional method, for example, by adding the above-mentioned binder, thickener, conductive material, solvent, etc. to the above-mentioned positive electrode active material to form a slurry positive electrode mixture, which is then applied to a current collector, dried, and pressed to increase density.

[0415] The densification can be performed by a hand press, a roller press, etc. The density of the positive electrode active material layer is preferably 1.0 g / cm 3 More preferably, 1.3 g / cm 3 More preferably, 1.5 g / cm 3 and preferably 5 g / cm 3 or less, more preferably 3.0 g / cm 3 More preferably 2.5 g / cm or less 3 The range is as follows. If the temperature exceeds this range, the permeability of the electrolyte near the current collector / active material interface will decrease, which may result in a decrease in charge / discharge characteristics, especially at high current densities, and high output may not be obtained. If the temperature falls below this range, the conductivity between the active materials will decrease, which may increase the battery resistance and prevent high output.

[0416] When using the composition of the present disclosure, the area of ​​the positive electrode active material layer is preferably larger than the outer surface area of ​​the battery exterior case from the viewpoint of improving high output and stability at high temperatures. Specifically, the total electrode area of ​​the positive electrode relative to the surface area of ​​the secondary battery exterior is preferably 15 times or more, and more preferably 40 times or more. In the case of a bottomed prismatic battery exterior case, the outer surface area refers to the total area calculated from the length, width, and thickness of the case portion filled with the power generating elements, excluding the terminal protrusions. In the case of a bottomed cylindrical battery exterior case, the outer surface area refers to the geometric surface area of ​​the case portion filled with the power generating elements, excluding the terminal protrusions, approximated as a cylinder. The total electrode area 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. In a structure in which positive electrode mixture layers are formed on both sides of a current collector foil, the total area refers to the sum of the areas calculated separately for each surface.

[0417] 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 mixture layer minus the thickness of the metal foil of the core material is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit on one side of the current collector, and is also preferably 500 μm or less, more preferably 450 μm or less.

[0418] Alternatively, a material having a different composition may be attached to the surface of the positive electrode plate, such as an oxide, such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, or bismuth oxide; a sulfate, such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, or aluminum sulfate; a carbonate, such as lithium carbonate, calcium carbonate, or magnesium carbonate; or carbon.

[0419] <Negative electrode> The negative electrode is composed of a negative electrode active material layer containing a negative electrode active material and a current collector.

[0420] The negative electrode active material is not particularly limited as long as it can electrochemically absorb and release lithium ions. Specific examples include carbon materials, silicon materials, metal materials, conductive polymers, etc. These may be used alone or in any combination of two or more.

[0421] Examples of the carbon material include natural graphite, artificial graphite, and graphite obtained by surface-treating such graphite with pitch or other organic substances and then carbonizing it. These may be used alone or in any combination of two or more.

[0422] The silicon material may be silicon alone or a composite material containing silicon and one or more other constituent elements (cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, boron, carbon, aluminum, phosphorus, etc.). These may be used alone or in any combination of two or more. From the viewpoint of obtaining an excellent battery capacity, the silicon material may be SiO v (0 <v≦2)、SnO w (0≦w≦2), Si—Co—C composite materials, and Si—Ni—C composite materials are preferred.

[0423] The silicon material is preferably used in combination with the carbon material, in which case the mass ratio of silicon material to carbon material is preferably 1-20:99-80.

[0424] Examples of the metal material include metal materials containing metal elements such as lithium and tin. The metal material may be a simple metal, or a compound such as an alloy, oxide, carbide, nitride, silicide, sulfide, or phosphide. These may be used alone or in any combination of two or more. From the viewpoint of obtaining an excellent battery capacity, metal materials containing lithium are preferred as the metal material, and lithium metal (simple lithium metal) is more preferred.

[0425] The lithium-containing metal material is preferably a material containing lithium and titanium from the viewpoint of high current density charge / discharge characteristics, and more preferably a composite oxide of lithium and titanium (hereinafter abbreviated as "lithium titanium composite oxide").

[0426] The lithium titanium composite oxide may be a compound represented by the general formula: Li x Ti y M z O4 [In the formula, M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb.] It is preferable that the compound is represented by the following 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 The structure of is particularly preferred because it has a good balance of battery performance.

[0427] A particularly preferred representative composition of the above compound is (i) Li 4 / 3 Ti 5 / 3 O4, (ii) Li1Ti2O4, (iii) Li4 / 5 Ti 11 / 5 O4. For the structure of Z≠0, for example, Li 4 / 3 Ti 4 / 3 Al 1 / 3 O4 is preferred.

[0428] The negative electrode mixture preferably further contains a binder, a thickener, and a conductive material.

[0429] Examples of the binder include the same 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, and particularly preferably 0.6% by mass or more, and is 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 ratio of the binder that does not contribute to the battery capacity increases, which may result in a decrease in battery capacity. On the other hand, if the ratio is below the above range, the strength of the negative electrode may be reduced.

[0430] In particular, when a rubber-like polymer such as SBR is contained as a 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, more preferably 2% by mass or less. Also, when a fluorine-based polymer such as polyvinylidene fluoride is contained as a main component, the ratio of the binder 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, more preferably 8% by mass or less.

[0431] Examples of the thickener include the same thickeners that can be used for the positive electrode as described above. The ratio of the thickener 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, more preferably 2% by mass or less. If the ratio of the thickener to the negative electrode active material is below the above range, the coating properties may be significantly reduced. On the other hand, if the ratio exceeds the above range, the ratio of the negative electrode active material in the negative electrode active material layer may be reduced, resulting in problems such as a decrease in battery capacity and an increase in resistance between the negative electrode active materials.

[0432] Examples of conductive materials for the negative electrode include metal materials such as copper and nickel; and carbon materials such as graphite and carbon black.

[0433] The solvent for forming the slurry is not particularly limited in type as long as it is capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as needed, and either an aqueous solvent or an organic solvent may be used. Examples of aqueous solvents include water and alcohol, and 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, hexamethylphosphamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, and hexane.

[0434] Examples of the material for the negative electrode current collector include copper, nickel, stainless steel, etc. Among these, copper foil is preferred from the viewpoints of ease of processing into a thin film and cost.

[0435] 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 capacity of the entire battery may be too low, and conversely, if it is too thin, it may be difficult to handle.

[0436] The negative electrode may be manufactured by a conventional method. For example, the negative electrode material may be prepared by adding the binder, thickener, conductive material, solvent, etc. to form a slurry, which is then applied to a current collector, dried, and pressed to increase density. When an alloy material is used, a thin film layer (negative electrode active material layer) containing the negative electrode active material may be formed by a vapor deposition method, a sputtering method, a plating method, or the like.

[0437] There are no particular restrictions on the electrode structure when the negative electrode active material is made into an electrode, but the density of the negative electrode active material present on the current collector must be 1 g cm -3 More than 1.2 g cm is preferable. -3 More preferably, 1.3 g cm -3 More than 2.2 g cm is particularly preferable. -3 Preferably less than 2.1 g cm -3 Less than 2.0 g cm is preferable. -3 Less than 1.9 g cm is more preferable. -3 The following is particularly preferred. 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, increasing the initial irreversible capacity and possibly leading to deterioration of high current density charge / discharge characteristics due to reduced permeability of the electrolyte near the current collector / negative electrode active material interface. If the density is below the above range, the conductivity between the negative electrode active materials may decrease, increasing the battery resistance and reducing the capacity per unit volume.

[0438] The thickness of the negative electrode plate is designed to match the positive electrode plate to be used and is not particularly limited, but the thickness of the composite layer minus the thickness of the metal foil of the core material is usually 15 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and is usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

[0439] Alternatively, a substance having a different composition may be attached to the surface of the negative electrode plate, such as oxides including aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide, sulfates including lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate, and carbonates including lithium carbonate, calcium carbonate, and magnesium carbonate.

[0440] <Separator> The secondary battery of the present disclosure preferably further includes a separator. The material and shape of the separator are not particularly limited as long as they are stable to the electrolyte solution and have excellent liquid retention properties, and any known separator can be used. Among them, it is preferable to use a material that is stable to the electrolyte solution, such as a resin, glass fiber, or inorganic material, and that is in the form of a porous sheet or nonwoven fabric, which has excellent liquid retention properties.

[0441] Examples of materials that can be used for the resin or glass fiber separator include polyolefins such as polyethylene and polypropylene, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, and glass filters. These materials may be used alone or in any combination and ratio, such as polypropylene / polyethylene two-layer films and polypropylene / polyethylene / polypropylene three-layer films. Among these, porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene are preferred for the separator, due to their excellent electrolyte permeability and shutdown effect.

[0442] The thickness of the separator is optional, 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, more preferably 30 μm or less. If the separator is thinner than the above range, the insulating properties and mechanical strength may be reduced. On the other hand, if the separator is thicker than the above range, not only may the battery performance such as rate characteristics be reduced, but also the energy density of the entire electrolyte battery may be reduced.

[0443] Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is optional, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, and is usually 90% or less, preferably 85% or less, more preferably 75% or less. If the porosity is too low, the membrane resistance tends to increase, resulting in poor rate performance. If the porosity is too high, the mechanical strength of the separator tends to decrease, resulting in poor insulation.

[0444] The average pore size of the separator can also be any value, but 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 likely to occur. If the average pore size is below the above range, the membrane resistance increases, which may result in a decrease in rate characteristics.

[0445] On the other hand, inorganic materials include, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate, and these are used in particulate or fibrous form.

[0446] As for the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. A thin film with a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferably used. In addition to the above-mentioned independent thin film, a separator can be used in which a composite porous layer containing the above-mentioned inorganic particles is formed on the surface layer 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.

[0447] <Battery design> The electrode group may have either a laminated structure of the positive electrode plate and the negative electrode plate sandwiched between the separator, or a structure of the positive electrode plate and the negative electrode plate spirally wound with the separator sandwiched between them. 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.

[0448] If the electrode group occupancy rate is below the above range, the battery capacity will be small, whereas if it exceeds the above range, the void space will be small, and the battery will become hot, causing the components to expand and the vapor pressure of the electrolyte liquid components to increase, resulting in an increase in internal pressure, which will degrade various battery characteristics such as repeated charge / discharge performance and high-temperature storage, and may even cause the gas release valve that releases internal pressure to the outside to operate.

[0449] Although the current collection structure is not particularly limited, in order to more effectively realize the improvement of the high current density charge / discharge characteristics by the electrolyte, it is preferable to use a structure that reduces the resistance of the wiring parts and joint parts. When the internal resistance is reduced in this way, the effect of using the electrolyte is particularly well exhibited.

[0450] When the electrode group has the above-mentioned 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 preferably used to reduce the resistance by providing multiple terminals within the electrode. When the electrode group has the above-mentioned wound structure, the internal resistance can be reduced by providing multiple lead structures on each of the positive electrode and negative electrode and bundling them to a terminal.

[0451] The material of the outer case is not particularly limited as long as it is stable against the electrolyte solution used. Specifically, metals such as nickel-plated steel sheet, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminate film of resin and aluminum foil (laminate film) can be used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloy and laminate film are preferably used.

[0452] Examples of exterior cases using metals include those in which metals are welded together to form a sealed, airtight structure by laser welding, resistance welding, or ultrasonic welding, or those in which the metals are used via a resin gasket to form a crimped structure. Examples of exterior cases using the above-mentioned laminate film include those in which resin layers are heat-sealed to form a sealed, airtight structure. In order to improve sealing properties, 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-sealing the resin layers via a current collecting terminal, a resin having a polar group or a modified resin into which a polar group has been introduced is preferably used as the interposed resin, since the metal and the resin are bonded together.

[0453] The shape of the secondary battery of the present disclosure is arbitrary, and examples thereof include cylindrical, prismatic, laminated, coin, large, etc. The shapes and configurations of the positive electrode, negative electrode, and separator can be changed according to the shape of each battery.

[0454] The present disclosure also includes a module including the secondary battery of the present disclosure.

[0455] The present disclosure also includes an electric double layer capacitor comprising the composition of the present disclosure. The electric double layer capacitor may include a positive electrode, a negative electrode, and the above-mentioned electrolyte solution. In the electric double layer capacitor, at least one of the positive electrode and the negative electrode is a polarizable electrode, and the following electrodes described in detail in Japanese Patent Application Laid-Open No. 9-7896 can be used as the polarizable electrode and non-polarizable electrode.

[0456] The polarizable electrode primarily made of activated carbon used in the present disclosure preferably contains inert carbon with a large specific surface area and a conductive agent such as carbon black that provides electronic conductivity. The polarizable electrode can be formed by various methods. For example, a polarizable electrode made of activated carbon and carbon black can be formed by mixing activated carbon powder, carbon black, and a phenolic resin, press-molding the mixture, and then firing and activating the mixture in an inert gas atmosphere and a water vapor atmosphere. Preferably, this polarizable electrode is bonded to a current collector using a conductive adhesive or the like.

[0457] Alternatively, activated carbon powder, carbon black, and a binder may be kneaded in the presence of alcohol, formed into a sheet, and dried to form a polarizable electrode. The binder may be, for example, polytetrafluoroethylene. Alternatively, activated carbon powder, carbon black, a binder, and a solvent may be mixed to form a slurry, which may then be coated onto a metal foil current collector and dried to form a polarizable electrode integrated with the current collector.

[0458] An electric double layer capacitor may be constructed by using polarizable electrodes mainly made of activated carbon on both electrodes, but it is also possible to use a non-polarizable electrode on one side, for example, a configuration in which a positive electrode mainly made of a battery active material such as a metal oxide is combined with a polarizable negative electrode mainly made of activated carbon, or a configuration in which a negative electrode mainly made of a carbon material that can reversibly occlude and release lithium ions, or a negative electrode made of lithium metal or a lithium alloy is combined with a polarizable positive electrode mainly made of activated carbon.

[0459] Further, in place of or in combination with activated carbon, carbonaceous materials such as carbon black, graphite, expanded graphite, porous carbon, carbon nanotubes, carbon nanohorns, and Ketjen black may be used.

[0460] The non-polarizable electrode is preferably made primarily of a carbon material capable of reversibly absorbing and releasing lithium ions, and the carbon material is used to absorb lithium ions. In this case, a lithium salt is used as the electrolyte. An electric double layer capacitor with this configuration can achieve a higher withstand voltage of over 4 V.

[0461] The solvent used to prepare the slurry for producing the electrode is preferably one that dissolves the binder, and is appropriately selected from N-methylpyrrolidone, dimethylformamide, toluene, xylene, isophorone, methyl ethyl ketone, ethyl acetate, methyl acetate, dimethyl phthalate, ethanol, methanol, butanol, and water depending on the type of binder.

[0462] Activated carbons used in polarizable electrodes include phenolic resin-based activated carbon, coconut shell-based activated carbon, and petroleum coke-based activated carbon. Of these, petroleum coke-based activated carbon and phenolic resin-based activated carbon are preferred because they provide a large capacity. Activation methods for activated carbon include steam activation and molten KOH activation, and activated carbons activated by molten KOH activation are preferred because they provide a larger capacity.

[0463] Preferred conductive agents for use in polarizable electrodes include carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, metal fiber, conductive titanium oxide, and ruthenium oxide. The amount of conductive agent such as carbon black used in polarizable electrodes is preferably 1 to 50 mass % of the total amount with activated carbon, so as to obtain good conductivity (low internal resistance), and because too much reduces the capacity of the product.

[0464] The activated carbon used for the polarizable electrodes should have an average particle size of 20 μm or less and a specific surface area of ​​1500 to 3000 m, so that an electric double layer capacitor with large capacity and low internal resistance can be obtained. 2 / g of activated carbon is preferably used. Preferred carbon materials for constituting an electrode mainly made of a carbon material capable of reversibly absorbing and desorbing lithium ions include natural graphite, artificial graphite, graphitized mesocarbon microspheres, graphitized whiskers, vapor-grown carbon fiber, a fired product of furfuryl alcohol resin, and a fired product of novolac resin.

[0465] The current collector may be any material as long as it is chemically and electrochemically resistant to corrosion. Stainless steel, aluminum, titanium, or tantalum is preferably used as the current collector for a polarizable electrode mainly made of activated carbon. Of these, stainless steel or aluminum is particularly preferred in terms of both the properties and price of the resulting electric double layer capacitor. Stainless steel, copper, or nickel is preferably used as the current collector for an electrode mainly made of a carbon material capable of reversibly absorbing and releasing lithium ions.

[0466] In addition, there are several ways to preliminarily store lithium ions in a carbon material that can reversibly store and release lithium ions: (1) mixing powdered lithium with a carbon material that can reversibly store and release lithium ions; (2) placing lithium foil on an electrode formed from a carbon material and a binder that can reversibly store and release lithium ions, and electrically contacting the electrode; immersing this electrode in an electrolyte solution containing a lithium salt to ionize the lithium and incorporate the lithium ions into the carbon material; and (3) placing an electrode formed from a carbon material and a binder that can reversibly store and release lithium ions on the negative side, placing lithium metal on the positive side, immersing the electrode in a non-aqueous electrolyte solution containing lithium salt as an electrolyte, and passing an electric current through the electrode to electrochemically incorporate the lithium in an ionized state into the carbon material.

[0467] Commonly known electric double layer capacitors include wound type electric double layer capacitors, laminate type electric double layer capacitors, and coin type electric double layer capacitors, and the electric double layer capacitor described above can also be of these types.

[0468] For example, a wound electric double layer capacitor is assembled by winding a positive electrode and a negative electrode, each consisting of a laminate (electrode) of a current collector and an electrode layer, with a separator interposed between them to prepare a wound element, placing the wound element in a case made of aluminum or the like, filling it with an electrolyte, preferably a non-aqueous electrolyte, and sealing it with a rubber seal.

[0469] The separator may be made of a conventionally known material and structure, such as a porous polyethylene film, polytetrafluoroethylene, or a nonwoven fabric of polypropylene fiber, glass fiber, or cellulose fiber.

[0470] Furthermore, a laminate-type electric double layer capacitor can be formed by laminating sheet-like positive and negative electrodes with an electrolytic solution and a separator interposed therebetween by a known method, or a coin-type electric double layer capacitor can be formed by fixing the positive and negative electrodes with a gasket and forming them into a coin shape with an electrolytic solution and a separator interposed therebetween.

[0471] The composition of the present disclosure is useful as an electrolyte solution for large-scale lithium-ion secondary batteries for hybrid vehicles and distributed power sources, and for electric double-layer capacitors.

[0472] The present disclosure also relates to a composition (second composition of the present disclosure) containing a compound (M) represented by the following formula (M) and a fluorinated ether (E) represented by the following formula (E): (M)Rf 1 -COOM (In the formula, Rf 1 is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li. (E)Rf 2 -OR (In the formula, Rf 2is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine.

[0473] The second composition of the present disclosure is a novel composition and can be used as a plating bath solvent, a pharmaceutical intermediate, etc.

[0474] In the second composition of the present disclosure, the form and content of the compound (M) and the fluorinated ether (E) are the same as those described for the composition of the present disclosure.

[0475] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0476] Next, the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0477] (Fabrication and evaluation of lithium metal secondary batteries) [Preparation of electrolyte] The materials were mixed in the proportions shown in Table 1 to obtain a non-aqueous electrolyte solution.

[0478] [Preparation of positive electrode] 94% by mass of LiMn2O4 (LMO) as the positive electrode active material, 3% by mass of acetylene black as the conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as the binder were mixed in N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to a 15 μm thick aluminum foil current collector, dried, and then compression-molded using a press. The electrode was cut into shapes with a width of 15 mm, a length of 20 mm, and an uncoated area of ​​5 mm, a length of 9 mm, to form the positive electrode.

[0479] [Preparation of negative electrode] A 0.15 mm thick lithium foil was cut into a width of 16 mm and a length of 21 mm as the negative electrode active material, and then rolled with a PTFE roll onto a Ni mesh with terminal sections of 17 mm wide, 22 mm long, and 5 mm wide, 9 mm long to form a negative electrode.

[0480] [Fabrication of laminated cells] The positive and negative electrodes prepared as described above were stacked on a polyethylene separator in the order of negative electrode, separator, and positive electrode to prepare a battery element. This battery element was inserted into a bag made of a laminate film in which both sides of an aluminum sheet (40 μm thick) were coated with a resin layer, with the positive and negative electrode terminals protruding, and the electrolyte solutions of the Examples and Comparative Examples listed in Table 1 were poured into the bag, which was then vacuum-sealed to prepare a sheet-shaped lithium metal secondary battery.

[0481] [Low temperature cycle test] The laminated cell manufactured as described above was subjected to constant current-constant voltage charging (hereinafter referred to as CC / CV charging) at 25°C to 4.1 V at a current equivalent to 0.2 C (0.05 C cut), and then discharged to 3.0 V at a constant current of 0.2 C. This constitutes one cycle, and 5 cycles of formation cycles were performed. Subsequently, 300 cycles of 0.5 C constant current-constant voltage charging and constant current discharging (between 4.1 and 3.0 V) were performed in a thermostatic bath at 0°C. The ratio of the discharge capacity at 300th cycle to the discharge capacity at 0°C at the first cycle was determined and defined as the cycle capacity retention rate (%). (Discharge capacity at 300th cycle) / (Discharge capacity at 1st cycle) x 100 = Cycle capacity retention rate (%)

[0482] [Evaluation of resistance increase rate] The battery was charged at a constant current of 0.2 C at 25°C to half of the initial discharge capacity. It was then discharged at 3.0 C at 25°C, and the voltage was measured after 10 seconds. The resistance was calculated from the voltage drop during discharge, and this was used as the IV resistance. This procedure was repeated before and after the low-temperature cycle test, and the resistance increase rate (%) was calculated using the following formula: (Resistance after low-temperature cycle test) / (Resistance before low-temperature cycle test) x 100 = Resistance increase rate (%)

[0483] [Table 1]

[0484] (Fabrication and evaluation of lithium-ion secondary batteries) [Preparation of electrolyte] The materials were mixed in the proportions shown in Table 2 to obtain a non-aqueous electrolyte solution.

[0485] [Preparation of positive electrode] Li(Ni) as a positive electrode active material 0.5 Mn 0.3 Co 0.2 98.0% by mass of )O2 (NMC532), 1.0% by mass of acetylene black as a conductive material, and 1.0% 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 a 15 μm thick aluminum foil current collector, dried, and then compression molded using a press. The electrode was cut into shapes with a width of 40 mm, a length of 45 mm, and an uncoated portion of 5 mm, a length of 9 mm, to form a positive electrode.

[0486] [Preparation of negative electrode] The negative electrode active materials were SiO powder, natural graphite powder, an aqueous dispersion of sodium carboxymethylcellulose (1% by mass sodium carboxymethylcellulose) as a thickener, and an aqueous dispersion of styrene-butadiene rubber (50% by mass styrene-butadiene rubber) as a binder. The SiO powder, natural graphite powder, thickener, and binder were mixed in an aqueous solvent at a solids ratio of 9.6 / 86.4 / 2 / 2 (mass %) to prepare a negative electrode mixture slurry. The resulting slurry was uniformly applied to a 10 μm thick copper foil current collector, dried, and then compressed using a press. The electrode was cut into shapes with a width of 41 mm, a length of 46 mm, and an uncoated section of 5 mm by 9 mm.

[0487] [Fabrication of laminated cells] The positive and negative electrodes prepared as described above and a polyethylene separator were laminated in this order to prepare a battery element. This battery element was inserted into a bag made of a laminate film in which both sides of an aluminum sheet (40 μm thick) were coated with a resin layer, with the positive and negative terminals protruding. The electrolyte solutions of the Examples and Comparative Examples in Table 2 were then poured into the bag, which was then vacuum-sealed to prepare a sheet-like lithium-ion secondary battery.

[0488] [Low temperature cycle test] The laminated cell manufactured as described above was subjected to constant current-constant voltage charging (hereinafter referred to as CC / CV charging) at 25°C at a current equivalent to 0.5 C up to 4.3 V (0.05 C cut), and then discharged to 3.0 V at a constant current of 0.5 C. This constitutes one cycle, and five cycles of formation cycles were performed. Subsequently, 150 cycles of 1 C constant current-constant voltage charging and constant current discharging (between 4.3 and 3.0 V) were performed in a thermostatic bath at 0°C. The ratio of the discharge capacity at 150th cycle to the discharge capacity at 0°C at the first cycle was calculated and defined as the cycle capacity retention rate (%). (Discharge capacity at 150th cycle) / (Discharge capacity at 1st cycle) x 100 = Cycle capacity retention rate (%)

[0489] [Evaluation of resistance increase rate] The battery was charged at a constant current of 0.5 C at 25°C to half of the initial discharge capacity. It was then discharged at 5.0 C at 25°C, and the voltage was measured after 20 seconds. The resistance was calculated from the voltage drop during discharge and used as the IV resistance. This procedure was repeated before and after the low-temperature cycle test, and the resistance increase rate (%) was calculated using the following formula: (Resistance after low-temperature cycle test) / (Resistance before low-temperature cycle test) x 100 = Resistance increase rate (%)

[0490] [Table 2]

[0491] The abbreviations in the table are as follows: <Lithium salt> LiPF6: Lithium hexafluorophosphate LiFSI: Lithium bis(fluorosulfonyl)imide LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide <Fluorinated ether (E)> E-1:HCF2-CF2-O-CH2-CF2-CF2H, E-2:HCF2-CF2-O-CH2-CH2-CH3 E-3:HCF2-CF2-O-CH2-CH2-O-CF2-CF2H <Compound (M)> M-1: Potassium difluoroacetate M-2: Sodium difluoroacetate <Other solvent components> EC: Ethylene carbonate EMC: Ethyl methyl carbonate DMC: Dimethyl carbonate DME:CH3-O-CH2-CH2-O-CH3 FEC: Fluoroethylene carbonate

Claims

1. An electrolyte composition comprising a compound (M) represented by the following formula (M): (M)Rf １ -COOM (wherein, Rf １ is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li.

2. The Rf １ is HCF ２ The composition for an electrolyte solution according to claim 1, wherein

3. The compound (M) is HCF ２ -COOK, and HCF ２ 3. The composition for an electrolyte solution according to claim 1, wherein the composition is at least one selected from the group consisting of —COONa.

4. 3. The composition for an electrolyte solution according to claim 1, wherein the content of the compound (M) is 0.0001 to 3% by mass based on the composition for an electrolyte solution.

5. 3. The composition for an electrolyte solution according to claim 1, which contains a fluorinated ether (E) represented by the following formula (E): (E)Rf ２ -O-R (wherein, Rf ２ is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine.

6. The Rf ２ is HCF ２ -CF ２ The composition for an electrolyte solution according to claim 5, wherein:

7. The R is -CH ２ -CF ２ -CF ２ H、 -CH ２ -CH ２ -CH ３ , or -CH ２ -CH ２ -O-CF ２ -CF ２ H 6. The electrolyte composition according to claim 5, wherein

8. The fluorinated ether (E) is HCF ２ -CF ２ -O-CH ２ -CF ２ -CF ２ H、 HCF ２ -CF ２ -O-CH ２ -CH ２ -CH ３ 、and HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H The electrolyte composition according to claim 5, which is at least one selected from the group consisting of:

9. 6. The composition for an electrolyte solution according to claim 5, wherein the content of the fluorinated ether (E) is 0.1 to 100% by volume relative to the solvent in the composition for an electrolyte solution.

10. LiPF ６ 3. The electrolyte composition according to claim 1, which contains at least one lithium salt selected from the group consisting of LiFSI, LiTFSI, and LiTFSI.

11. The compound (M) is HCF ２ -COOK, and HCF ２ -COONa, the content of the compound (M) is 0.0001 to 1% by mass relative to the electrolyte solution composition, HCF ２ -CF ２ -O-CH ２ -CF ２ -CF ２ H、 HCF ２ -CF ２ -O-CH ２ -CH ２ -CH ３ and HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H At least one fluorinated ether (E) selected from the group consisting of:

3. The composition for an electrolyte solution according to claim 1, wherein the content of the fluorinated ether (E) is 5 to 80% by volume relative to the solvent in the composition for an electrolyte solution.

12. A secondary battery comprising the electrolyte composition according to claim 11 and lithium metal as a negative electrode active material.

13. The compound (M) is HCF ２ -COOK, and HCF ２ -COONa, the content of the compound (M) is 0.01 to 0.1% by mass relative to the electrolyte solution composition; HCF ２ -CF ２ -O-CH ２ -CF ２ -CF ２ H、 HCF ２ -CF ２ -O-CH ２ -CH ２ -CH ３ and HCF ２ -CF ２ -O-CH ２ -CH ２ -O-CF ２ -CF ２ H At least one fluorinated ether (E) selected from the group consisting of:

3. The composition for an electrolyte solution according to claim 1, wherein the content of the fluorinated ether (E) is 25 to 30% by volume relative to the solvent in the composition for an electrolyte solution.

14. A secondary battery comprising the electrolyte composition according to claim 13 and a silicon material as a negative electrode active material.

15. 3. The electrolyte composition according to claim 1, which is for a secondary battery.

16. An electrochemical device comprising the electrolyte composition according to claim 1 or 2.

17. A secondary battery comprising the electrolyte composition according to claim 1 or 2.

18. A lithium ion secondary battery comprising the electrolyte composition according to claim 1 or 2.

19. A composition containing a compound (M) represented by the following formula (M) and a fluorinated ether (E) represented by the following formula (E): (M)Rf １ -COOM (wherein, Rf １ is a fluoroalkyl group having 1 to 6 carbon atoms, and M is an alkali metal other than Li. (E)Rf ２ -O-R (wherein, Rf ２ is a fluoroalkyl group having 1 to 6 carbon atoms, and R is H or an alkyl group having 1 to 6 carbon atoms. The alkyl group of R may have an ether bond and / or fluorine.

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