Nonaqueous electrolyte solution, method for producing nonaqueous electrolyte solution, battery, method for producing battery, and vehicle

Abstract

The present invention relates to a nonaqueous electrolyte solution containing an electrolyte, a nonaqueous solvent, and a compound having an Si-F bond. The electrolyte contains PF6 anions and sulfonylimide anions as constituent anions. The molar concentration [A] of the sulfonylimide anions in the nonaqueous electrolyte solution and the total molar concentration [B] of the PF6 anions and sulfonylimide anions in the nonaqueous electrolyte solution satisfy the following relationship in expression (I-1): 0.05≤[A] / [B]<1.00.

Description

Non-aqueous electrolyte, method for producing a non-aqueous electrolyte, battery, method for producing a battery, and vehicle

[0001] The present invention relates to a non-aqueous electrolyte, a method for producing a non-aqueous electrolyte, a battery, a method for producing a battery, and a vehicle.

[0002] Lithium-ion rechargeable batteries, among others, are widely used in applications such as power supplies for small devices like mobile phones and laptops, and power supplies for vehicles like electric cars. Therefore, numerous studies have been conducted on various battery components, including the positive electrode, negative electrode, and electrolyte, as means of improving battery characteristics.

[0003] Numerous studies have been conducted on electrolytes, including additives, electrolytes, and solvents, with the aim of improving battery characteristics. For example, Patent Document 1 discloses a study on improving cycle capacity and gas emissions at 25°C by including a specific silicon compound in the electrolyte. Patent Document 2 discloses a study on improving gas generation during high-temperature storage by including a specific silicon compound in the electrolyte.

[0004] U.S. Patent Application Publication No. 2019 / 0305372, Specification International Publication No. 2021 / 235505

[0005] In recent years, batteries are used in a wide range of environments, from high-temperature regions to cold climates, and there is a growing demand for batteries that can be used over a wide temperature range. In particular, in cold climates, the internal resistance of batteries increases, making it difficult to obtain sufficient performance, which can be a critical risk for battery use in cold environments.

[0006] However, the non-aqueous electrolytes described in Patent Documents 1 and 2 had insufficient battery characteristics in low-temperature environments, particularly in terms of cycle capacity maintenance rate when repeatedly charging and discharging at -10°C.

[0007] The present invention has been made in view of these problems, and the object of the present invention is to provide a non-aqueous electrolyte that exhibits good low-temperature characteristics when used in a battery. One aspect of the low-temperature characteristics in the above object is the characteristics at -10°C. Another aspect of the low-temperature characteristics in the above object is the cycle capacity retention rate when repeatedly charged and discharged. Furthermore, another aspect of the low-temperature characteristics in the above object is the cycle capacity retention rate at -10°C. The object of the present invention is also to provide a method for producing an electrolyte that exhibits good low-temperature characteristics when used in a battery, a battery that exhibits good low-temperature characteristics and a method for producing the same, and a vehicle in which the low-temperature characteristics of the battery are excellent.

[0008] The inventors of the present invention have conducted diligent studies to solve the above problems and have found a compound having an Si-F bond and PF as an electrolyte. ６ Anions and sulfonylimid anions are contained in a non-aqueous electrolyte, and PF ６ By maintaining a constant ratio of anions to sulfonylimide anions, we discovered that the electrolyte exhibits excellent low-temperature properties when used in batteries, thus completing the present invention.

[0009] The reason why the non-aqueous electrolyte according to the present invention exhibits excellent low-temperature properties is not clear, but it is thought to be as follows. The sulfonylimid anion has an anionic moiety on the nitrogen atom. On the other hand, in compounds having an Si-F bond, the silicon atom is cationic due to the difference in electronegativity between the fluorine atom and the silicon atom. Therefore, the interaction between the anionic moiety of the sulfonylimid anion and the cationic moiety of the compound having an Si-F bond promotes the film formation reaction on the electrode active material by the sulfonylimid anion.

[0010] The coating formed from sulfonylimide anions is PF ６ Because it has higher ionic conductivity compared to coatings composed solely of anions, it is believed that it can maintain high performance even in low-temperature environments where lithium ion conductivity decreases. PF ６ If the ratio of sulfonylimid anions to anions is too low, a coating with sufficient ionic conductivity cannot be formed. ６When no anion is included and only a sulfonylimide anion is used, the influence of corrosion of battery members by the sulfonylimide anion becomes remarkable, and it becomes difficult to use practically. In contrast, PF ６ When the content ratio of the PF ６ anion and the sulfonylimide anion is within a specific range, it has been found that a suitable amount of film can be formed on the electrode active material, and a battery excellent in low-temperature characteristics can be provided.

[0011] That is, the gist of the present invention is as follows. [1] A non-aqueous electrolyte solution containing an electrolyte, a non-aqueous solvent, and a compound having a Si-F bond, wherein the electrolyte contains a PF ６ anion and a sulfonylimide anion, and the molar concentration [A] of the sulfonylimide anion in the non-aqueous electrolyte solution and the total molar concentration [B] of the PF ６ anion and the sulfonylimide anion in the non-aqueous electrolyte solution satisfy the relationship of the following formula (I-1). (I-1): 0.05 ≦ [A] / [B] < 1.00 [2] The non-aqueous electrolyte solution according to [1], wherein [A] and [B] satisfy the relationship of the following formula (I-2). (I-2): 0.20 ≦ [A] / [B] < 1.00 [3] The non-aqueous electrolyte solution according to [1] or [2], wherein [A] and [B] satisfy the relationship of the following formula (I-3). (I-3): 0.50 ≦ [A] / [B] < 1.00 [4] The non-aqueous electrolyte solution according to any one of [1] to [3], wherein [A] and [B] satisfy the relationship of the following formula (I-4). (I-4): 0.55 ≦ [A] / [B] < 1.00 [5] The non-aqueous electrolyte solution according to any one of [1] to [4], including a compound represented by the following general formula (1) as the compound having a Si-F bond.

[0012]

[0013] (In the general formula (1), R １ to R ３ each independently represents a fluorine atom, a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group having a polar group.)

[0014] [6] R in the general formula (1) １and R ２ Each of these is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, and R ３ The non-aqueous electrolyte according to [5], wherein R is a hydrocarbon group which may be substituted with a fluorine atom or a halogen atom, or a hydrocarbon group which has a polar group. [7] R in the general formula (1) １ ~R ３ The non-aqueous electrolyte according to [5] or [6], wherein each of them is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group. [8] R in the general formula (1) １ and R ２ Each of these is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, and R ３ The non-aqueous electrolyte according to [5] or [6], wherein R is a fluorine atom. [9] R in the general formula (1) １ R is a hydrocarbon group which may be substituted with a halogen atom, ３ The non-aqueous electrolyte according to [5] or [6], wherein R is a hydrocarbon group or fluorine atom which may be substituted with a halogen atom.

[10] R in the general formula (1) １ R is a hydrocarbon group which may be substituted with a halogen atom, ３ A non-aqueous electrolyte according to any one of [5] to [7] or [9], wherein R is a hydrocarbon group which may be substituted with a halogen atom.

[11] R in the general formula (1) ２ The non-aqueous electrolyte according to any one of [5] to

[10] above, wherein R is a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group.

[12] R in the general formula (1) ２ The non-aqueous electrolyte according to any one of [5] to

[11] above, wherein R is a hydrocarbon group having four or more carbon atoms, which may be substituted with a halogen atom, or a hydrocarbon group having a polar group.

[13] R in the general formula (1) above ２ A non-aqueous electrolyte according to any one of [5] to

[12] above, wherein is a hydrocarbon group having a polar group.

[0015]

[14] A method for producing a non-aqueous electrolyte containing an electrolyte, a non-aqueous solvent, and a compound having an Si-F bond, wherein the constituent anion is PF ６ The process includes at least one of the following steps: dissolving an electrolyte containing an anion and a sulfonylimid anion, and a compound having an Si-F bond, in a non-aqueous solvent; and adding a raw material for a compound having an Si-F bond to a solution containing a non-aqueous solvent to generate a compound having an Si-F bond in the solution, wherein the molar concentration [A] of the sulfonylimid anion in the non-aqueous electrolyte and the PF in the non-aqueous electrolyte ６ A method for producing a non-aqueous electrolyte, wherein the total molar concentration [B] of the anion and sulfonylimid anion satisfies the following relationship (I-1): (I-1): 0.05 ≤ [A] / [B] < 1.00

[0016]

[15] A battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte according to any one of [1] to

[13] above.

[16] A method for manufacturing a battery, comprising the steps of housing the positive electrode and the negative electrode in an outer casing, and injecting the non-aqueous electrolyte according to any one of [1] to

[13] above into the outer casing.

[17] A vehicle comprising the battery according to

[15] above.

[0017] The non-aqueous electrolyte according to this embodiment exhibits excellent low-temperature characteristics when used in a battery. Furthermore, the electrolyte obtained by the manufacturing method of the electrolyte according to this embodiment exhibits excellent low-temperature characteristics when used in a battery. Furthermore, the battery according to this embodiment exhibits excellent low-temperature characteristics. Furthermore, the battery obtained by the manufacturing method of the battery according to this embodiment exhibits excellent low-temperature characteristics. Moreover, the vehicle according to this embodiment exhibits excellent low-temperature characteristics of the battery.

[0018] The following describes in detail embodiments for carrying out the present invention, but the following description is merely one example of an embodiment of the present invention, and the present invention is not limited to these. Furthermore, the present invention can be modified and implemented at will without departing from its essence. In this specification, "~" is used to mean that the numerical values ​​described before and after it are included as the lower limit and upper limit. In this specification, mass% and weight%, and parts by mass and parts by weight are synonymous.

[0019] [1. Non-aqueous electrolyte] The non-aqueous electrolyte according to this embodiment contains an electrolyte, a non-aqueous solvent, and a compound having an Si-F bond, wherein the electrolyte has PF as a constituent anion. ６ It contains anions and sulfonylimid anions. The molar concentration of sulfonylimid anions in the non-aqueous electrolyte [A] and PF in the non-aqueous electrolyte ６ The molar concentration [B] of the total anion and sulfonylimid anion satisfies the following relationship (I-1): (I-1): 0.05 ≤ [A] / [B] < 1.00

[0020] [1-1. Compounds having Si-F bonds] The compounds having Si-F bonds in this embodiment are not particularly limited as long as they have Si-F bonds in their molecule, but examples include compounds represented by the following general formula (1).

[0021]

[0022] (In general formula (1), R １ ~R ３ Each of these independently represents a fluorine atom, a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group.

[0023] [R １ ] In general formula (1), R １ This represents a hydrocarbon group which may be substituted with a fluorine atom or a halogen atom, or a hydrocarbon group which has a polar group. Among these, hydrocarbon groups which may be substituted with a fluorine atom or a halogen atom are preferred, and hydrocarbon groups which may be substituted with a halogen atom are more preferred.

[0024] The above R １ If R is a hydrocarbon group which may be substituted with a halogen atom, １The hydrocarbon group which may be substituted with halogen atoms preferably has 1 to 10 carbon atoms. Specific examples of hydrocarbon groups which may be substituted with halogen atoms having 1 to 10 carbon atoms include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and halogenated hydrocarbon groups in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with halogen atoms. Specific examples of halogen atoms that substitute for hydrogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms and chlorine atoms being preferred, and fluorine atoms being particularly preferred. The above halogen atoms are preferred because they tend to suppress side reactions on the electrode active material surface of the compound represented by general formula (1). １ If R is a hydrocarbon group which may be substituted with a halogen atom, １ The halogen-unsubstituted hydrocarbon group having 1 to 10 carbon atoms is preferred, an alkyl or alkenyl group having 1 to 10 carbon atoms is more preferred, an alkyl group having 1 to 10 carbon atoms is even more preferred, and an alkyl group having 1 to 3 carbon atoms is even more preferred. The above-mentioned groups are preferred because they tend to have less steric hindrance to the compound represented by general formula (1) and can interact favorably with the sulfonylimide anion.

[0025] The above R １The hydrocarbon group having 1 to 10 carbon atoms may be substituted with a halogen atom. Specific examples of alkyl groups when the hydrocarbon group is an alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups; branched alkyl groups such as i-propyl, methylpropyl, t-butyl, methylbutyl, methylpentyl, methylhexyl, methylheptyl, methyloctyl, and methylnonyl groups; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclohexylmethyl, cyclohexylethyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, and methylcyclohexylmethyl groups. Among the alkyl groups mentioned above, linear alkyl groups or branched alkyl groups are preferred, and linear alkyl groups are more preferred. Furthermore, when the alkyl group is a hydrocarbon group having 1 to 10 carbon atoms, which may be substituted with a halogen atom, the number of carbon atoms in the alkyl group is more preferably 1 to 6, even more preferably 1 to 4, and the alkyl group is more preferably a methyl group or an ethyl group, with the methyl group being the most preferred. The alkyl groups mentioned above are preferred because they tend to have less steric hindrance to the compound represented by general formula (1) and can interact favorably with the sulfonylimid anion.

[0026] The above R １The hydrocarbon group is a C1-C10 hydrocarbon group which may be substituted with a halogen atom. When the hydrocarbon group is an alkenyl group, specific examples of alkenyl groups include C2-C10 alkenyl groups such as vinyl group, allyl group, isopropenyl group, methallyl group, 2-butenyl group, 3-methyl-2-butenyl group, 3-butenyl group, or 4-pentenyl group. Linear alkenyl groups are preferred as the alkenyl group. More preferably, the alkenyl group is a C2-C6 alkenyl group such as vinyl group, allyl group, methallyl group, or 2-butenyl group, even more preferably, a C2-C4 alkenyl group such as vinyl group, allyl group, or methallyl group, particularly preferably, a vinyl group or allyl group, and most preferably, a vinyl group. The above-mentioned alkenyl group is preferred because the compound represented by general formula (1) tends to be able to interact favorably with the sulfonylimid anion.

[0027] The above R １ The hydrocarbon group is a C1-C10 hydrocarbon group which may be substituted with a halogen atom, and when the hydrocarbon group is an alkynyl group, the alkynyl group is substantially a C2-C10 alkynyl group. Specific examples include C2-C10 alkynyl groups such as ethynyl, 2-propynyl, 2-butynyl, 3-butynyl, 4-pentynyl, or 5-hexynyl groups, and a linear alkynyl group is preferred as the alkynyl group. More preferably, it is a C2-C6 alkynyl group such as ethynyl, 2-propynyl, 2-butynyl, or 3-butynyl group, even more preferably a C2-C4 alkynyl group such as 2-propynyl or 3-butynyl group, and particularly preferably a 2-propynyl group. The above-mentioned alkynyl groups are preferred because the compound represented by general formula (1) tends to be able to interact favorably with the sulfonylimid anion.

[0028] The above R １The hydrocarbon group is a C1-C10 hydrocarbon group which may be substituted with a halogen atom, and if the hydrocarbon group is an aryl group, the aryl group is substantially a C6-C10 aryl group. Specific examples include C6-C12 aryl groups such as a phenyl group, a tolyl group, or a mesityl group. Among these, a C6-C7 aryl group such as a phenyl group or a tolyl group is preferred, and a phenyl group is particularly preferred. The above-mentioned aryl group is preferred because the compound represented by general formula (1) tends to be able to interact favorably with the sulfonylimid anion.

[0029] The above R １ When the hydrocarbon group is a C1-C10 hydrocarbon group substituted with a halogen atom, a halogenated hydrocarbon group means a hydrocarbon group in which the hydrogen atoms are substituted with halogen atoms. Specific examples include hydrocarbon groups having C1-C10, such as alkyl groups, alkenyl groups, alkynyl groups, and aryl groups, in which some or all of the hydrogen atoms are substituted with halogen atoms. More specifically, examples include trifluoromethyl group, 2,2,2-trifluoroethyl group, 3-fluoropropyl group, 4-fluorobutyl group, 5-fluoropentyl group, 6-fluorohexyl group, 2-fluorophenyl group, and pentafluorophenyl group. Among these, C1-C4 halogenated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, 3-fluoropropyl group, and 4-fluorobutyl group are preferred, and C1-C4 fluorinated alkyl groups are more preferred. Furthermore, C1 or C2 halogenated alkyl groups such as trifluoromethyl group and 2,2,2-trifluoroethyl group are more preferred, and C1 or C2 fluorinated alkyl groups are even more preferred. Among these, the trifluoromethyl group is even more preferred. This is because, as mentioned above, the halogenated hydrocarbon group tends to suppress side reactions on the electrode active material surface of the compound represented by general formula (1), making it preferable.

[0030] The above R １Specific examples of hydrocarbon groups having polar groups include carbonate group (-OC(=O)O-), carboxylic acid ester group (-OC(=O)-), ether group (-O-), thioether group (-S-), sulfonyl oxide group (-S(=O)-), sulfonyl group (-S(=O)-) ２ -), sulfonic acid ester group (-O (S=O) ２ -), sulfite ester group (-O (S=O) ２ O-), sulfate ester group (-O (S=O) ２ Examples of hydrocarbon groups include those having a phosphine group (-O-), a phosphine group (-P-), a phosphine oxide group (-P(=O)-), a phosphonic acid ester group (-P(=O)(OR)O-), a phosphate ester group (-OP(=O)(OR)O-), an amino group (-NR-), an amide group (-N(R)C(=O)-), a urea group (-N(R)C(=O)N(R)-), a nitrile group (-CN), an isocyanate group (-NCO), a thioisocyanate group (-NCS), etc. However, in the above functional groups, R represents a hydrocarbon group which may be substituted with a hydrogen atom or a halogen atom having 1 to 10 carbon atoms. Specific examples and preferred examples of hydrocarbon groups having 1 to 10 carbon atoms which may be substituted with a halogen atom are given above. １ These are similar to the specific examples and preferred examples of C1-C10 hydrocarbon groups that may be substituted with halogen atoms.

[0031] The above R １ When the hydrocarbon group has a polar group, the compound having the Si-F bond is preferably concentrated on the electrode active material surface, and side reactions of the compound having the Si-F bond on the electrode active material surface are suppressed. From this viewpoint, the hydrocarbon group having the polar group is preferably a group represented by the following general formula (2).

[0032]

[0033] (In general formula (2), R ４ and R ５ Each of these independently represents a hydrocarbon group having 1 to 10 carbon atoms, which may be substituted with halogen atoms. X represents a divalent alkylene group having 1 to 10 carbon atoms, and Y １ ~Y ３Each of the following independently represents a single bond or an oxygen atom; Z represents a carbon atom, a sulfur atom, or a phosphorus atom; n represents an integer of 1 or 2; and m represents an integer of 0 or 1. However, when Z is a carbon atom, n is 1 and m is 0; when Z is a sulfur atom, n is 1 or 2 and m is 0; and when Z is a phosphorus atom, n is 1 and m is 1.

[0034] In the above general formula (2), R ４ and R ５ Each of these independently represents a hydrocarbon group having 1 to 10 carbon atoms, which may be substituted with a halogen atom. Specific and preferred examples are shown in the above R. １ These are similar to the specific examples and preferred examples of C1-C10 hydrocarbon groups that may be substituted with halogen atoms.

[0035] In the above general formula (2), specific examples of the divalent alkylene group having 1 to 10 carbon atoms, which is X, include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, and octamethylene groups. Among the above, linear alkylene groups or branched alkylene groups are preferred, and linear alkylene groups are more preferred. Furthermore, the number of carbon atoms in the alkylene group is preferably 1 to 6, more preferably 1 to 4, and particularly preferably 1 to 3. The above alkylene groups are preferred because the compound represented by general formula (1) tends to be able to interact favorably with the sulfonylimid anion.

[0036] In the general formula (2) above, Z represents a carbon atom, a sulfur atom, or a phosphorus atom. Among these, a carbon atom or a sulfur atom is preferred, and a carbon atom is particularly preferred. This is because the aforementioned atoms tend to suppress side reactions on the electrode active material surface of the compound represented by general formula (1), making them preferable.

[0037] When Z is a carbon atom, n is 1, m is 0, and Y １ and Y ３ Each of these independently represents a single bond or an oxygen atom. Among them, Y １ is a single bond or oxygen atom, Y ３ A preferred embodiment is one in which Y is an oxygen atom. １This is an oxygen atom, Y ３ A more preferable embodiment is one in which the atom is an oxygen atom. This is preferable because, in the above embodiment, side reactions on the electrode active material surface of the compound represented by general formula (1) tend to be suppressed.

[0038] When Z is a sulfur atom, n is 1 or 2, m is 0, and Y １ and Y ３ Each of these independently represents a single bond or an oxygen atom. n is preferably 2. １ is a single bond or oxygen atom, Y ３ A preferred embodiment is one in which Y is an oxygen atom. １ It is a single bond, Y ３ A more preferable embodiment is one in which the atom is an oxygen atom. This is preferable because, in the above embodiment, side reactions on the electrode active material surface of the compound represented by general formula (1) tend to be suppressed.

[0039] When Z is a phosphorus atom, n is 1 and m is 1. １ ~Y ３ Each of these independently represents a single bond or an oxygen atom. １ This is an oxygen atom, Y ２ This is an oxygen atom, Y ３ A form in which is a single bond or an oxygen atom is preferred, Y １ This is an oxygen atom, Y ２ This is an oxygen atom, Y ３ A configuration in which the bond is a single bond is more preferable. This configuration is preferable because it tends to suppress side reactions on the electrode active material surface of the compound represented by general formula (1).

[0040] The above R １ Among them, R is preferred because it exhibits low steric hindrance and tends to interact favorably with sulfonylimid anions. １A hydrocarbon group having 1 to 10 carbon atoms may be substituted with a fluorine atom or a halogen atom; a hydrocarbon group having 1 to 10 carbon atoms may be substituted with a halogen atom; a hydrocarbon group having 1 to 10 carbon atoms that is not substituted with a halogen atom is even more preferred; an alkyl group having 1 to 10 carbon atoms is even more preferred; an alkyl group having 1 to 3 carbon atoms is particularly preferred; a methyl group or an ethyl group is particularly preferred; and a methyl group is most preferred.

[0041] [R ２ ] In general formula (1), R ２ The symbol represents a hydrocarbon group which may be substituted with a fluorine atom, a halogen atom, or a hydrocarbon group which has a polar group. Among these, hydrocarbon groups which may be substituted with a halogen atom or a hydrocarbon group which has a polar group are preferred.

[0042] The above R ２ If R is a hydrocarbon group which may be substituted with a halogen atom, ２ Specific examples of hydrocarbon groups that may be substituted with halogen atoms include the above R １ The specific examples of C1-C10 hydrocarbon groups that may be substituted with halogen atoms are similar to those shown. Among these, halogen-unsubstituted C1-C10 hydrocarbon groups are preferred, C1-C10 alkyl groups are more preferred, and C4-C10 alkyl groups are particularly preferred. The above-mentioned groups are preferred because the volatility of the compound represented by general formula (1) is moderate, making electrolyte production, storage, and handling easier.

[0043] The above R ２ For specific and preferred examples of hydrocarbon groups having polar groups, see above R １ These are similar to the specific examples and preferred examples of hydrocarbon groups having polar groups shown.

[0044] The above R ２Among them, a hydrocarbon group which may be substituted with a halogen atom or a hydrocarbon group having a polar group is preferable, a hydrocarbon group having a polar group represented by an alkyl group having 1 to 10 carbon atoms or a general formula (2) is more preferable, and an alkyl group having 4 to 10 carbon atoms or a group in which Z is a carbon atom among hydrocarbon groups having a polar group represented by a general formula (2) is particularly preferable. When it is the above group, the volatility of the compound represented by a general formula (1) is moderate, and it is preferable because the production, storage, and handling of an electrolyte become easy.

[0045] [R ３ In general formula (1), R ３ represents a fluorine atom, a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group having a polar group. Among them, a fluorine atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom is preferable.

[0046] When the above R ３ is a hydrocarbon group which may be substituted with a halogen atom, specific examples of the hydrocarbon group which may be substituted with a halogen atom of R ３ are the same as those shown as specific examples of the hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom of the above R １ Among them, a halogen-free hydrocarbon group having 1 to 10 carbon atoms is preferable, an alkyl group or an alkenyl group having 1 to 10 carbon atoms is more preferable, an alkyl group having 1 to 10 carbon atoms is further preferable, an alkyl group having 1 to 3 carbon atoms is even more preferable, a methyl group or an ethyl group is particularly preferable, and a methyl group is most preferable. When it is the above group, the steric hindrance of the compound represented by a general formula (1) is small, and it tends to be able to interact suitably with a sulfonylimide anion, and thus it is preferable.

[0047] Regarding specific examples and preferable examples of the hydrocarbon group having a polar group which is the above R ３ , they are the same as those shown as specific examples and preferable examples of the hydrocarbon group having a polar group of the above R １ respectively.

[0048] Regarding the above R ３Among them, a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a fluorine atom or a halogen atom is preferable, a hydrocarbon group having 1 to 10 carbon atoms unsubstituted with a fluorine atom or a halogen atom is more preferable, a fluorine atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group having 1 to 10 carbon atoms is further preferable, an alkyl group having 1 to 10 carbon atoms is even more preferable, an alkyl group having 1 to 3 carbon atoms is even more preferable, a methyl group or an ethyl group is particularly preferable, and a methyl group is most preferable. When it is the above-mentioned group, the steric hindrance of the compound represented by the general formula (1) is small, and it tends to be able to interact preferably with the sulfonylimide anion, and thus it is preferable.

[0049] [R １ , R ２ , and R ３ 's preferred combination] In the compound represented by the general formula (1) in the present embodiment, R １ is a hydrocarbon group which may be substituted with a halogen atom, and R ３ is preferably a hydrocarbon group which may be substituted with a halogen atom or a fluorine atom, and R １ and R ３ are more preferably methyl groups. Further, it is also preferable that R ２ is a hydrocarbon group having 4 or more carbon atoms which may be substituted with a halogen atom, or a hydrocarbon group having a polar group. In the compound represented by the general formula (1) in the present embodiment, R １ is a hydrocarbon group which may be substituted with a halogen atom, and R ２ is a hydrocarbon group having 4 or more carbon atoms which may be substituted with a halogen atom, or a hydrocarbon group having a polar group, and R ３ is preferably a hydrocarbon group which may be substituted with a halogen atom or a fluorine atom, and R １ and R ３ are methyl groups, and it is more preferable that R ２ is a hydrocarbon group having 4 or more carbon atoms which may be substituted with a halogen atom, or a hydrocarbon group having a polar group. In the compound represented by the general formula (1) in the present embodiment, R １ and R ２ are each independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group having a polar group, R３ It is also preferable that R is a hydrocarbon group which may be substituted with a fluorine atom or a halogen atom, or a hydrocarbon group which has a polar group. １ ~R ３ It is also preferable that each of them independently be a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, R １ and R ２ Each of these is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, and R ３ It is also preferable that R is a fluorine atom. ２ It is also preferable that the hydrocarbon group may be substituted with a halogen atom, or that it is a hydrocarbon group having a polar group.

[0050] Furthermore, the compound represented by general formula (1) in this embodiment is R １ R is an alkyl group having 1 to 10 carbon atoms or a fluorine atom, ２ R is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group, ３ Preferably, R is a fluorine atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group. １ is an alkyl group having 1 to 10 carbon atoms, and R ２ R is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group represented by general formula (2), ３ A more preferable embodiment is one in which R is a fluorine atom, an alkyl group having 1 to 10 carbon atoms, or an alkenyl group. １ is an alkyl group having 1 to 10 carbon atoms, and R ２ R is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group represented by general formula (2), ３ A more preferable embodiment is one in which R is an alkyl group having 1 to 10 carbon atoms. １ is an alkyl group having 1 to 3 carbon atoms, R ２ A is an alkyl group having 4 to 10 carbon atoms or a hydrocarbon group having a polar group represented by general formula (2), where Z is a carbon atom, and R ３ A more preferable embodiment is one in which R is an alkyl group having 1 to 3 carbon atoms. １ is a methyl group, R ２is a group in which Z is a carbon atom among alkyl groups having 4 to 10 carbon atoms or hydrocarbon groups having a polar group represented by the general formula (2), and R ３ The embodiment in which is a methyl group is particularly preferable.

[0051] Specific examples of the compound represented by the general formula (1) are shown below. The compound represented by the general formula (1) is not limited to the following examples.

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Among the above, the compound represented by the general formula (1) is such that R １ is an alkyl group having 1 to 10 carbon atoms or a fluorine atom, and R ２ is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group, and R ３ is a fluorine atom, an alkyl group having 1 to 10 carbon atoms or an alkenyl group. As specific examples thereof, the compounds represented by (A-1) to (A-23), (B-1) to (B-18), (C-1) to (C-32), and (D-1) to (D-18) are preferable. Also, R １ is an alkyl group having 1 to 10 carbon atoms, and R ２ is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group represented by the general formula (2), and R ３A compound that is a fluorine atom, an alkyl group or an alkenyl group having 1 to 10 carbon atoms is more preferable, and specific examples thereof include the compounds represented by (A-1) to (A-23), (B-1) to (B-18), and (C-1) to (C-32). Further, R １ is an alkyl group having 1 to 10 carbon atoms, and R ２ is an alkyl group having 1 to 10 carbon atoms or a hydrocarbon group having a polar group represented by the general formula (2), and R ３ is an alkyl group having 1 to 10 carbon atoms is more preferable, and specific examples thereof include the compounds represented by (A-1) to (A-23) and (B-1) to (B-18). Further, R １ is an alkyl group having 1 to 3 carbon atoms, and R ２ is an alkyl group having 4 to 10 carbon atoms or a group in which Z is a carbon atom among the hydrocarbon groups having a polar group represented by the general formula (2), and R ３ is an alkyl group having 1 to 3 carbon atoms is more preferable, and specific examples thereof include (A-1) to (A-23) are more preferable.

[0063] The content of the compound having a Si-F bond in the non-aqueous electrolyte according to the present embodiment is preferably 0.0001 to 20% by mass. Here, from the viewpoint of improving the low-temperature characteristics, the above content is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, further preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, still more preferably 0.3% by mass or more, extremely preferably 0.7% by mass, and particularly preferably 1.5% by mass or more. Further, from the viewpoint of suppressing an increase in the viscosity of the non-aqueous electrolyte, the above content is preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 3% by mass or less. When two or more compounds having a Si-F bond are contained, the total content thereof is preferably within the above range.

[0064] As a method for incorporating a compound having an Si-F bond into a non-aqueous electrolyte according to this embodiment, examples include a method of incorporating the electrolyte and the compound having an Si-F bond into a non-aqueous solvent, and a method of adding a raw material for the compound having an Si-F bond to a solution containing a non-aqueous solvent and generating the compound having an Si-F bond in the solution. In the method of incorporating the electrolyte and the compound having an Si-F bond into a non-aqueous solvent, the electrolyte and the compound having an Si-F bond may be incorporated into the non-aqueous solvent simultaneously, or they may be incorporated separately, and the order is not limited. In the method of adding a raw material for the compound having an Si-F bond to a solution containing a non-aqueous solvent and generating the compound having an Si-F bond in the solution, when adding the raw material for the compound having an Si-F bond to the non-aqueous solvent, the electrolyte and the raw material for the compound having an Si-F bond may be incorporated into the non-aqueous solvent simultaneously, or they may be incorporated separately, and the order is not limited. When using a method of adding a compound having an Si-F bond to a non-aqueous electrolyte, the amount of the compound having an Si-F bond used in the preparation of the electrolyte often differs from the content of the compound having an Si-F bond obtained when the battery is actually disassembled. Specifically, the content measured when the battery is disassembled after charging and discharging and the electrolyte is extracted is often significantly lower than the amount used in the preparation of the electrolyte and the actual production of the battery. Therefore, if even a very small amount of the compound having an Si-F bond can be detected in the electrolyte extracted from a disassembled battery, it is considered to be a non-aqueous electrolyte according to this embodiment.

[0065] Furthermore, when a battery is manufactured using an electrolyte containing a compound having an Si-F bond in this embodiment, even if the electrolyte extracted after disassembling the battery contains only a very small amount of the compound having an Si-F bond, other components of the battery may contain the compound having an Si-F bond. Specifically, compounds having an Si-F bond are often detected on the positive electrode, negative electrode, or separator. Therefore, if a compound having an Si-F bond is detected on one or more of the positive electrode, negative electrode, and separator, the total amount of the compound having an Si-F bond contained in the electrolyte and other components can be considered to have been present in the electrolyte.

[0066] In this embodiment, when using a method to incorporate a compound having an Si-F bond into a non-aqueous electrolyte, i.e., a non-aqueous electrolyte, by adding a raw material for the compound having an Si-F bond to a solution containing a non-aqueous solvent, the theoretical amount of the compound having an Si-F bond calculated from the amount of the raw material for the compound having an Si-F bond added during electrolyte preparation often differs from the actual content of the compound having an Si-F bond obtained when the battery is disassembled. Specifically, the content measured when the battery is disassembled after charging and discharging and the electrolyte is extracted is often significantly lower than the theoretical amount of the compound having an Si-F bond produced when it is contained in the electrolyte and actually used to manufacture the battery. Therefore, if even a very small amount of the compound having an Si-F bond can be detected in the electrolyte extracted after disassembling the battery, it is considered to be a non-aqueous electrolyte according to this embodiment.

[0067] When a battery is manufactured using a method in which a raw material for a compound having Si-F bonds is added to a non-aqueous electrolyte to generate a compound having Si-F bonds in the non-aqueous electrolyte, even if the electrolyte extracted after disassembling the battery contains only a very small amount of the compound having Si-F bonds, other components of the battery may contain the compound having Si-F bonds. Specifically, compounds having Si-F bonds are often detected on the positive electrode, negative electrode, or separator. Therefore, if a compound having Si-F bonds is detected on one or more of the positive electrode, negative electrode, and separator, the total amount of the compound having Si-F bonds contained in the electrolyte and other components can be considered to have been present in the electrolyte.

[0068] (mol ratio of compound having Si-F bond to sulfonylimide anion) The ratio of the content (mol concentration) of the compound having Si-F bond to the content (mol concentration) of sulfonylimide anion in the non-aqueous electrolyte according to this embodiment, i.e., the mol ratio expressed as {compound having Si-F bond [mol / L] / sulfonylimide anion [mol / L]}, is preferably 0.0001 to 30. Here, from the viewpoint of balancing low-temperature and high-temperature characteristics, the above mol ratio is usually 0.0001 or more, preferably 0.001 or more, more preferably 0.005 or more, even more preferably 0.01 or more, even more preferably 0.05 or more, particularly preferably 0.1 or more, and usually 30 or less, preferably 20 or less, more preferably 10 or less, even more preferably 5 or less, even more preferably 3 or less, especially preferably 2 or less, particularly preferably 1 or less, and most preferably 0.5 or less. Note that the content ratios of the compound having Si-F bond and the sulfonylimide anion refer to the total content ratio if two or more types are included.

[0069] In this specification, the identification of compounds containing Si-F bonds and the content of compounds containing Si-F bonds are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify compounds containing Si-F bonds or measure the content of compounds containing Si-F bonds using nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0070] Compounds having an Si-F bond can be produced by known methods. For example, methods include fluorinating chlorosilane with hydrogen fluoride, hydrofluoric acid, metal fluoride, etc., and fluorinating alkoxysilane with hydrogen fluoride, hydrofluoric acid, metal fluoride, boron trifluoride, boron trifluoride complex, etc.

[0071] Methods for incorporating a compound having an Si-F bond into a non-aqueous electrolyte according to this embodiment include adding the compound having an Si-F bond to a non-aqueous electrolyte which is a solution containing a non-aqueous solvent, and adding a raw material for a compound having an Si-F bond to a non-aqueous electrolyte which is a solution containing a non-aqueous solvent, thereby generating the compound having an Si-F bond in the non-aqueous electrolyte.

[0072] [1-2. Electrolyte] The electrolyte in this embodiment only needs to be one that can dissociate into cations and anions, even slightly, when dissolved in a non-aqueous solvent, and the constituent anions are PF ６ The electrolyte is not particularly limited as long as it contains anions and sulfonylimid anions. From the viewpoint of increasing solubility, alkali metal salts are preferred for the electrolyte, lithium salts, sodium salts, and potassium salts are more preferred, and from the viewpoint of improving cycle characteristics, lithium salts are even more preferred. When the electrolyte according to this embodiment is used in a lithium-ion battery, the counter cation of the electrolyte is preferably a lithium cation. When the electrolyte according to this embodiment is used in a sodium-ion battery, the counter cation of the electrolyte is preferably a sodium cation. When the electrolyte according to this embodiment is used in a potassium-ion battery, the counter cation of the electrolyte is preferably a potassium cation.

[0073] In this embodiment, the electrolyte is composed of PF anions. ６ It contains anions and sulfonyliimide anions. Let [A] be the molar concentration of sulfonyliimide anions in the non-aqueous electrolyte, and PF ６ When the total molar concentration of anions and sulfonylimid anions is [B], the content ratio expressed as [A] / [B] satisfies the following relationship (I-1): (I-1): 0.05 ≤ [A] / [B] < 1.00

[0074] Furthermore, in the non-aqueous electrolyte according to this embodiment, PF ６ When anions and sulfonilimide anions are present, it is impossible to distinguish whether they are present as constituent anions of the electrolyte or as constituent anions of other components. Therefore, PF is also considered a constituent anion of other components. ６ If anions or sulfonylimide anions are included, their respective content ratios shall also be included in [A] and [B] above. Furthermore, if the non-aqueous electrolyte according to this embodiment contains two or more types of sulfonylimide anions, the content ratio (molar concentration) of the sulfonylimide anions represents their total amount.

[0075] PF in this embodiment ６ The countercation in a compound (salt) containing an anion as a constituent anion is not particularly limited. For example, LiPF4 is a lithium salt. ６ As a sodium salt, NaPF ６ As a potassium salt, KPF ６ These are some examples.

[0076] In this embodiment, the sulfonylimide anion is sulfonylimide [N-S (=O)] ２ While there are no particular restrictions as long as the anion has a skeleton, from the viewpoint of exhibiting good low-temperature properties, fluorosulfonylimide [F-N-S (=O)] ２ It is preferable that the anion has a ] skeleton, and difluorosulfonylimide [N(FSO ２ ) ２It is more preferable that the anion has a ] skeleton. Furthermore, the countercation in a compound (salt) containing a sulfonylimid anion as a constituent anion is not particularly limited. For example, as a lithium imide salt, LiN(FSO ２ ) ２ , LiN (FSO ２ ) (CF ３ SO ２ ), LiN (CF ３ SO ２ ) ２ ,LiN(C ２ F ５ SO ２ ) ２ , LiN (FSO ２ ) (F ２ Examples include LiN(FSO4), lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide; and others. Among these, LiN(FSO4) ２ ) ２ , LiN (FSO ２ ) (CF ３ SO ２ ), LiN (CF ３ SO ２ ) ２ , LiN (FSO ２ ) (F ２ PO), LiN(C ２ F ５ SO ２ ) ２ Preferably, LiN(FSO ２ ) ２ , LiN (FSO ２ ) (F ２ PO) is more preferred, and LiN (FSO) ２ ) ２ The most preferred is NaN(FSO) as the sodium imide salt. ２ ) ２ NaN(FSO) ２ ) (CF ３ SO ２ ), NaN(CF ３ SO ２ ) ２ NaN(C) ２ F ５ SO ２ ) ２ NaN(FSO)２ ) (F ２ Examples include NaN(FSO4), sodium cyclic 1,2-perfluoroethanedisulfonylimide, sodium cyclic 1,3-perfluoropropanedisulfonylimide; and others. Among these, NaN(FSO4) ２ ) ２ NaN(FSO) ２ ) (CF ３ SO ２ ), NaN(CF ３ SO ２ ) ２ NaN(C) ２ F ５ SO ２ ) ２ NaN(FSO) ２ ) (F ２ PO is preferred, and NaN(FSO) ２ ) ２ NaN(FSO) ２ ) (F ２ PO) is more preferred, and NaN(FSO) ２ ) ２ This is particularly preferred. KN(FSO) as potassium imide salt. ２ ) ２ , KN (FSO ２ ) (CF ３ SO ２ ), KN (CF ３ SO ２ ) ２ , KN (C ２ F ５ SO ２ ) ２ , KN (FSO ２ ) (F ２ Examples include potassium cyclic 1,2-perfluoroethanedisulfonylimide, potassium cyclic 1,3-perfluoropropanedisulfonylimide, etc. Among these, KN (FSO ２ ) ２ , KN (FSO ２ ) (CF ３ SO ２ ), KN (CF ３ SO ２ ) ２ , KN (C ２ F ５ SO ２ ) ２ , KN (FSO２ ) (F ２ PO is preferred, N (FSO) ２ ) ２ , KN (FSO ２ ) (F ２ PO) is more preferred, KN (FSO) ２ ) ２ That is particularly preferable.

[0077] The molar concentration ratio (content ratio) expressed as [A] / [B] above preferably satisfies the relationship 0.05 ≤ [A] / [B] < 1.00, as shown in formula (I-1), more preferably satisfies the relationship 0.20 ≤ [A] / [B] < 1.00 in formula (I-2), even more preferably satisfies the relationship 0.50 ≤ [A] / [B] < 1.00 in formula (I-3), and particularly preferably satisfies the relationship 0.55 ≤ [A] / [B] < 1.00 in formula (I-4). Here, the molar concentration ratio is preferably 0.05 or higher, more preferably 0.10 or higher, even more preferably 0.20 or higher, even more preferably 0.35 or higher, even more preferably 0.50 or higher, and particularly preferably 0.55 or higher. Within the above range, a suitable amount of sulfonylimide anion can form a film on the electrode active material surface, and the balance between low-temperature and high-temperature characteristics is excellent, which is therefore preferable. Furthermore, [A] / [B] is preferably less than 1.00, more preferably 0.99 or less, even more preferably 0.95 or less, even more preferably 0.9 or less, and particularly preferably 0.8 or less. Within the above range, corrosion of the battery components by sulfonylimid anions tends to be suppressed, which is therefore preferable. In this specification, PF ６ The identification and content of anions and fluorosulfonylimid anions are measured by nuclear magnetic resonance (NMR) analysis. PF ６ If identification and measurement of the content of anions and fluorosulfonylimid anions are difficult with nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) and ion chromatography-mass spectrometry may be used in combination.

[0078] The electrolyte in this embodiment is composed of PF as an anion. ６In addition to compounds having anions and sulfonylimid anions, other electrolytes may also be included. Specific examples of other electrolytes include the following:

[0079] Examples of lithium salts include lithium fluoroborate, lithium fluorophosphate, lithium tungstate, lithium carboxylate, lithium sulfonate, lithium imide, lithium methide, lithium oxalate, and fluorine-containing organic lithium salts. A single lithium salt may be used, or two or more may be used in any ratio and combination.

[0080] Lithium salts are used as lithium fluoroborate salts (LiBF) from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics. ４ Li as lithium fluorophosphate salt ２ PO ３ F, LiPO ２ F ２ ; LiFSO as lithium sulfonate salt ３ ,CH ３ SO ３ Li, CF ３ SO ３ Li; as lithium sulfate salt, CH ３ SO ４ Li, CF ３ SO ４ Li, C ２ H ５ SO ４ Li, C ２ F ５ SO ４ Li, C ３ H ５ SO ４ Li, C ３ H ３ SO ４ Li; as lithium methide salt, LiC(FSO) ２ ) ３ LiC (CF ３ SO ２ ) ３ LiC(C ２ F ５ SO ２ ) ３Lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, and lithium tris(oxalate) phosphate are preferred as lithium oxalate salts, and LiBF is preferred from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics. ４ LiPO ２ F ２ Lithium bis(oxalate) borate, LiFSO ３ This is preferable.

[0081] Examples of sodium salts include sodium fluoroborate salts, sodium fluorophosphate salts, sodium tungstate salts, sodium carboxylate salts, sodium sulfonate salts, sodium imide salts, sodium methide salts, sodium oxalate salts, and fluorine-containing organic sodium salts. Sodium salts may be used individually or in any ratio and combination of two or more types.

[0082] Sodium salts are used as sodium fluoroborate salts (NaBF) from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics. ４ ;Na as sodium fluorophosphate ２ PO ３ F, NaPO ２ F ２ ;NaFSO as sodium sulfonate salt ３ ,CH ３ SO ３ Na, CF ３ SO ３ Na; as sodium sulfate salt, CH ３ SO ４ Na, CF ３ SO ４ Na, C ２ H ５ SO ４ Na, C ２ F ５ SO ４ Na, C ３ H ５ SO４ Na, C ３ H ３ SO ４ Na; as sodium methide salt, NaC(FSO) ２ ) ３ NaC(CF ３ SO ２ ) ３ NaC(C ２ F ５ SO ２ ) ３ ;Sodium difluorooxalate borate, sodium bis(oxalate) borate, sodium tetrafluorooxalate phosphate, sodium difluorobis(oxalate) phosphate, and sodium tris(oxalate) phosphate are preferred as sodium oxalate salts, and from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, NaBF ４ NaPO ２ F ２ Sodium bis(oxalate) borate, NaFSO ３ This is preferable.

[0083] Examples of potassium salts include potassium fluoroborate, potassium fluorophosphate, potassium tungstate, potassium carboxylate, potassium sulfonate, potassium imide, potassium methide, potassium oxalate, and fluorine-containing organic potassium salts. Potassium salts may be used individually or in any ratio and combination of two or more types.

[0084] Potassium salts are used as potassium fluoroborate (KBF) from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics. ４ ; as potassium fluorophosphate, K ２ PO ３ F, KPO ２ F ２ ; as potassium sulfonate, KFSO ３ ,CH ３ SO ３ K, CF ３ SO ３K; as potassium sulfate, CH ３ SO ４ K, CF ３ SO ４ K, C ２ H ５ SO ４ K, C ２ F ５ SO ４ K, C ３ H ５ SO ４ K, C ３ H ３ SO ４ K; as potassium methide salt, KC (FSO ２ ) ３ , KC (CF ３ SO ２ ) ３ , KC (C ２ F ５ SO ２ ) ３ Potassium difluorooxalate borate, potassium bis(oxalate) borate, potassium tetrafluorooxalate phosphate, potassium difluorobis(oxalate) phosphate, and potassium tris(oxalate) phosphate are preferred as potassium oxalate salts, and from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, KBF ４ , KPO ２ F ２ Potassium bis(oxalate) borate, KFSO ３ This is preferable.

[0085] The electrolyte content in the electrolyte solution according to this embodiment is preferably 5 to 20% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 20% by mass or less, more preferably 18% by mass or less, and even more preferably 16% by mass or less. Here, if two or more types of electrolytes are included, the above content refers to the total content of those electrolytes. In this specification, the identification of electrolytes and the electrolyte content are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify electrolytes or measure the electrolyte content by nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0086] When using two or more electrolytes, it is preferable to combine a first electrolyte and a second electrolyte from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics.

[0087] The first electrolyte is preferably an electrolyte with a high degree of ion dissociation and primarily responsible for carrier transport between electrodes, such as LiBF. ４ LiPF ６ , LiN (FSO ２ ) ２ More preferably, LiPF ６ , LiN (FSO ２ ) ２ More preferably, LiPF ６ The second electrolyte is preferably one with a low degree of ion dissociation and which is mainly responsible for roles other than carrier transport between electrodes, such as film formation on the electrode active material, such as LiPO ２ F ２ Lithium bis(oxalate) borate, LiFSO ３ ,CH ３ SO ４ Li, C ２ H ５ SO ４ Li is more preferable, LiPO２ F ２ LiFSO ３ ,CH ３ SO ４ Li, C ２ H ５ SO ４ Li is even more preferable, LiPO ２ F ２ LiFSO ３ That is particularly preferable.

[0088] The combination of the first and second electrolytes can be appropriately selected based on the degree of ionization and effects of the electrolytes, for example, LiPF ６ and LiPO ２ F ２ LiPF ６ and lithium bis(oxalate) borate, LiPF ６ and LiFSO ３ LiPF ６ and CH ３ SO ４ Li, LiPF ６ and C ２ H ５ SO ４ Li, LiN (FSO ２ ) ２ and LiPO ２ F ２ , LiN (FSO ２ ) ２ and lithium bis(oxalate) borate, LiN(FSO) ２ ) ２ and LiFSO ３ , LiN (FSO ２ ) ２ and CH ３ SO ４ Li, LiN (FSO ２ ) ２ and C ２ H ５ SO ４ Li is one example. The combination of the first and second electrolytes is LiPFF, from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics. ６ and LiPO ２ F ２ LiPF ６ and LiFSO ３LiPF ６ and CH ３ SO ４ Li, LiPF ６ and C ２ H ５ SO ４ Li, LiN (FSO ２ ) ２ and LiPO ２ F ２ , LiN (FSO ２ ) ２ and LiFSO ３ , LiN (FSO ２ ) ２ and CH ３ SO ４ Li, LiN (FSO ２ ) ２ and C ２ H ５ SO ４ Li is preferred, LiPF ６ and LiPO ２ F ２ LiPF ６ and LiFSO ３ , LiN (FSO ２ ) ２ and LiPO ２ F ２ , LiN (FSO ２ ) ２ and LiFSO ３ This is preferable.

[0089] The content of the first electrolyte in the electrolyte solution according to this embodiment is preferably 4 to 19% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 4% by mass or more, more preferably 6% by mass or more, and even more preferably 8% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content is preferably 19% by mass or less, more preferably 17% by mass or less, and even more preferably 15% by mass or less. Here, if two or more types of first electrolytes are included, the above content refers to the total content of those electrolytes.

[0090] The content of the second electrolyte in the electrolyte according to this embodiment is preferably 0.001 to 5% by mass. Here, from the viewpoint of improving the DC resistance maintenance rate after high-temperature storage and the gas generation suppression effect after high-temperature storage, the above content 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. Furthermore, from the viewpoint of improving the DC resistance maintenance rate after high-temperature storage and the gas generation suppression effect after high-temperature storage, the above content is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. Here, if two or more types of second electrolytes are included, the above content refers to the total content of those electrolytes.

[0091] The mass ratio of the first electrolyte to the second electrolyte (content of the second electrolyte (mass%) / content of the first electrolyte (mass%)) is preferably 0.0001 to 0.5. Here, from the viewpoint of improving the DC resistance maintenance rate after high-temperature storage and the effect of suppressing gas generation after high-temperature storage, the above mass ratio is preferably 0.0001 or higher, more preferably 0.001 or higher, and even more preferably 0.01 or higher. Furthermore, from the viewpoint of improving the DC resistance maintenance rate after high-temperature storage and the effect of suppressing gas generation after high-temperature storage, the above mass ratio is preferably 0.5 or lower, more preferably 0.4 or lower, and even more preferably 0.3 or lower. Note that the above ratio can be appropriately determined depending on the type of battery to which the electrolyte according to this embodiment is applied and the usage environment. Here, if the first electrolyte or the second electrolyte contains two or more compounds, the above content rates refer to the total content of those compounds.

[0092] [1-3. Non-aqueous solvents] In this embodiment, the non-aqueous solvent is PF as the constituent anion. ６ The electrolyte containing anions and sulfonylimide anions, as well as any non-aqueous solvent that dissolves compounds having Si-F bonds, are not particularly limited. From the viewpoint of suppressing oxidation-reduction decomposition in the battery, organic solvents are preferred as the non-aqueous solvent.

[0093] Examples of organic solvents include saturated cyclic carbonates, linear carbonates, linear carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds. One organic solvent may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of suppressing oxidation-reduction decomposition in the battery, saturated cyclic carbonates, linear carbonates, linear carboxylic acid esters, cyclic carboxylic acid esters, ether compounds, and sulfone compounds are preferred organic solvents, and saturated cyclic carbonates, linear carbonates, and linear carboxylic acid esters are more preferred.

[0094] Examples of combinations of two or more organic solvents include a combination of saturated cyclic carbonate and linear carbonate, a combination of saturated cyclic carbonate and linear carboxylic acid ester, a combination of saturated cyclic carbonate and cyclic carboxylic acid ester, a combination of linear carbonate and linear carboxylic acid ester, and a combination of saturated cyclic carbonate, linear carbonate, and linear carboxylic acid ester. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, it is preferable that the combination of two or more organic solvents be a combination of saturated cyclic carbonate and linear carbonate, or a combination of saturated cyclic carbonate, linear carbonate, and linear carboxylic acid ester.

[0095] The content rate of the non-aqueous solvent in the electrolytic solution according to this embodiment is preferably 84 to 95% by mass. Here, from the viewpoints of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content rate is preferably 84% by mass or more, more preferably 86% by mass or more, and still more preferably 88% by mass or more. Also, from the viewpoints of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the above content rate is preferably 95% by mass or less, more preferably 93% by mass or less, and still more preferably 91% by mass or less. Here, when two or more non-aqueous solvents are included, the above content rate means the total content rate thereof. In this specification, the identification of the non-aqueous solvent and the content rate of the non-aqueous solvent are measured by nuclear magnetic resonance (NMR) analysis. When it is difficult to identify the non-aqueous solvent and measure the content rate of the non-aqueous solvent only by nuclear magnetic resonance (NMR) analysis, analyses such as infrared spectroscopy (IR) analysis and gas chromatography (GC) mass spectrometry may be used in combination.

[0096] [1-3-1. Saturated cyclic carbonate] As the saturated cyclic carbonate serving as the non-aqueous solvent in this embodiment, for example, ethylene carbonate, propylene carbonate, butylene carbonate, erythritol bis(carbonate), etc. may be mentioned. The saturated cyclic carbonate may be used alone or two or more thereof may be used in any ratio and combination. The saturated cyclic carbonate is preferably ethylene carbonate or propylene carbonate, and more preferably ethylene carbonate, from the viewpoint of improving the ionic dissociation degree of alkali metals.

[0097] When saturated cyclic carbonate is used as the non-aqueous solvent, the content of saturated cyclic carbonate relative to the total non-aqueous solvent is preferably 3 to 90 volume percent. Here, from the viewpoint of suppressing the decrease in electrical conductivity due to the decrease in dielectric constant of the electrolyte and improving high-current discharge characteristics, stability to the negative electrode, cycle characteristics, oxidation-reduction resistance of the electrolyte, and high-temperature storage characteristics, the above content is preferably 3 volume percent or more, more preferably 5 volume percent or more, and even more preferably 10 volume percent or more. Furthermore, from the viewpoint of suppressing the decrease in electrical conductivity due to the decrease in dielectric constant of the electrolyte and improving high-current discharge characteristics, stability to the negative electrode, cycle characteristics, oxidation-reduction resistance of the electrolyte, and high-temperature storage characteristics, the above content is preferably 90 volume percent or less, more preferably 85 volume percent or less, and even more preferably 80 volume percent or less. Here, if two or more saturated cyclic carbonates are included, the above content refers to the total content of those two or more. In this specification, volume percent refers to the ratio of volume at 25°C and 1 atm.

[0098] [1-3-2. Chain-like carbonates] Examples of chain-like carbonates that serve as non-aqueous solvents in this embodiment include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propylisopropyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, methylphenyl carbonate, and methyl-2,2,2-trifluoroethyl carbonate. One type of chain-like carbonate may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of suppressing an increase in the viscosity of the electrolyte, chain-like carbonates having 3 to 5 carbon atoms are preferred, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are more preferred.

[0099] When a linear carbonate is used as the non-aqueous solvent, the content of the linear carbonate relative to the total non-aqueous solvent is preferably 15 to 90 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 15 volume percent or more, more preferably 20 volume percent or more, and even more preferably 25 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 90 volume percent or less, more preferably 85 volume percent or less, and even more preferably 80 volume percent or less. Here, if two or more types of linear carbonates are included, the above content refers to the total content of those types.

[0100] In this embodiment, the non-aqueous solvent is preferably a combination of ethylene carbonate and a chain carbonate, and more preferably a combination of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, from the viewpoint of suppressing the increase in viscosity of the electrolyte and improving electrical conductivity.

[0101] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of ethylene carbonate relative to the total non-aqueous solvent is preferably 15 to 45 volume percent. Here, from the viewpoint of improving the rate characteristics due to improved ion dissociation, the above content is preferably 15 volume percent or more, more preferably 20 volume percent or more, and even more preferably 30 volume percent or more. Furthermore, from the viewpoint of improving the rate characteristics due to improved ion dissociation, the above content is preferably 45 volume percent or less, and more preferably 40 volume percent or less.

[0102] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of dimethyl carbonate relative to the total non-aqueous solvent is preferably 20 to 50% by volume. From the viewpoint of suppressing an increase in the viscosity of the electrolyte, the above content is preferably 20% by volume or more, and more preferably 30% by volume or more. From the viewpoint of improving the low-temperature characteristics of the battery, the above content is preferably 50% by volume or less, and even more preferably 45% by volume or less.

[0103] When ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate are used as non-aqueous solvents, the content of ethyl methyl carbonate relative to the total non-aqueous solvent is preferably 20 to 50 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 20 volume percent or more, and more preferably 30 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 50 volume percent or less, and even more preferably 45 volume percent or less.

[0104] [1-3-3. Chain-like Carboxylic Acid Esters] Examples of chain-like carboxylic acid esters that serve as non-aqueous solvents in this embodiment include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, ethyl isobutyrate, and methyl pivalate. One type of chain-like carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate are preferred, and methyl acetate, ethyl acetate, and methyl propionate are more preferred.

[0105] The above-mentioned linear carboxylic acid ester may be a linear carboxylic acid ester in which some of the hydrogen atoms are replaced with fluorine atoms. Examples of fluorine-substituted linear carboxylic acid esters include methyl trifluoroacetate, ethyl trifluoroacetate, 2,2-difluoroethyl acetate, and 2,2,2-trifluoroethyl acetate. One type of fluorine-substituted linear carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of suppressing the increase in viscosity of the electrolyte, methyl trifluoroacetate and ethyl trifluoroacetate are preferred as the fluorine-substituted linear carboxylic acid ester, and methyl trifluoroacetate is more preferred.

[0106] When a linear carboxylic acid ester is used as the non-aqueous solvent, the content of the linear carboxylic acid ester relative to the total non-aqueous solvent is preferably 1 to 70% by volume. Here, from the viewpoint of improving the electrical conductivity of the electrolyte and enhancing the high-current discharge characteristics of the battery, the above content is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 15% by volume or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, suppressing the decrease in electrical conductivity, suppressing the increase in negative electrode resistance, and ensuring that the high-current discharge characteristics of the battery are within a good range, the above content is preferably 70% by volume or less, more preferably 50% by volume or less, and even more preferably 40% by volume or less. Here, if two or more linear carboxylic acid esters are included, the above content refers to the total content of those esters.

[0107] [1-3-4. Cyclic Carboxylic Acid Esters] Examples of cyclic carboxylic acid esters that serve as non-aqueous solvents in this embodiment include γ-butyrolactone and γ-valerolactone. One type of cyclic carboxylic acid ester may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving electrical conductivity, γ-butyrolactone is preferred as the cyclic carboxylic acid ester.

[0108] The above-mentioned cyclic carboxylic acid ester may be a cyclic carboxylic acid ester in which some of the hydrogen atoms are replaced with fluorine atoms. Examples of fluorine-substituted cyclic carboxylic acid esters include 3-fluorotetrahydrofuran-2-one and 4-fluorotetrahydrofuran-2-one. A single fluorine-substituted cyclic carboxylic acid ester may be used, or two or more may be used in any ratio and combination. From the viewpoint of improving oxidation resistance, 3-fluorotetrahydrofuran-2-one is preferred as the fluorine-substituted cyclic carboxylic acid ester.

[0109] When a cyclic carboxylic acid ester is used as a non-aqueous solvent, the content of the cyclic carboxylic acid ester relative to the total non-aqueous solvent is preferably 1 to 70% by volume. Here, from the viewpoint of improving the electrical conductivity of the electrolyte and enhancing the high-current discharge characteristics of the battery, the above content is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 15% by volume or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, suppressing the decrease in electrical conductivity, suppressing the increase in negative electrode resistance, and ensuring that the high-current discharge characteristics of the battery are within a good range, the above content is preferably 70% by volume or less, more preferably 50% by volume or less, and even more preferably 40% by volume or less. Here, if two or more cyclic carboxylic acid esters are included, the above content refers to the total content of those esters.

[0110] [1-3-5. Ether Compounds] Examples of ether compounds that serve as non-aqueous solvents in this embodiment include chain ethers having 3 to 10 carbon atoms such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether; and cyclic ethers having 3 to 6 carbon atoms such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 1,4-dioxane. The ether compound may be an ether compound in which some of the hydrogen atoms are substituted with fluorine atoms. The ether compound may be used alone, or two or more may be used in any ratio and combination.

[0111] From the viewpoint of suppressing the increase in viscosity of the electrolyte, the above ether compounds are preferably chain ethers having 3 to 10 carbon atoms and cyclic ethers having 3 to 6 carbon atoms. Of the chain ethers having 3 to 10 carbon atoms, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferred from the viewpoint of having high solvation ability to lithium ions, improving ion dissociation, suppressing the increase in viscosity of the electrolyte, and improving ionic conductivity. Of the cyclic ethers having 3 to 6 carbon atoms, tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane are preferred from the viewpoint of improving ionic conductivity.

[0112] When an ether compound is used as a non-aqueous solvent, the content of the ether compound relative to the total non-aqueous solvent is preferably 1 to 30 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 1 volume percent or more, more preferably 2 volume percent or more, and even more preferably 3 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 30 volume percent or less, more preferably 25 volume percent or less, and even more preferably 20 volume percent or less. Here, if two or more ether compounds are included, the above content refers to the total content of those compounds.

[0113] [1-3-6. Sulfone Compounds] The sulfone compound that serves as the non-aqueous solvent in this embodiment may be a cyclic sulfone or a chain sulfone. One sulfone compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving ionic conductivity, the number of sulfonyl groups in the sulfone compound is preferably 1 to 2, and more preferably 1.

[0114] Examples of the above-mentioned cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones (sulfolanes), and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. A single cyclic sulfone may be used, or two or more may be used in any ratio and combination. From the viewpoint of suppressing the increase in viscosity of the electrolyte, cyclic sulfones having 3 to 6 carbon atoms are preferred, chain-like sulfones having 3 to 5 carbon atoms are more preferred, and sulfolanes are even more preferred.

[0115] Examples of sulfolanes include sulfolane; sulfolane derivatives such as 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane. Sulfolanes may be used individually or in any ratio and combination of two or more. From the viewpoint of improving ionic conductivity, sulfolane and sulfolane derivatives are preferred, and sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane are more preferred.

[0116] From the viewpoint of improving oxidation resistance, sulfolane derivatives are preferably sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with fluorine atoms, sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with alkyl groups, and sulfolane derivatives in which one or more hydrogen atoms bonded to carbon atoms constituting the sulfolane ring are substituted with fluorine-substituted alkyl groups. More preferably are 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, and 3-trifluoromethylsulfolane.

[0117] Examples of the above-mentioned chain-like sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, and pentafluoroethyl methyl sulfone. One type of chain-like sulfone may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving the high-temperature storage stability of the electrolyte, chain-like sulfones having 2 to 6 carbon atoms are preferred, chain-like sulfones having 2 to 5 carbon atoms are more preferred, and dimethyl sulfone, ethyl methyl sulfone, and monofluoromethyl methyl sulfone are even more preferred.

[0118] When a sulfone compound is used as a non-aqueous solvent, the content of the sulfone compound relative to the total non-aqueous solvent is preferably 0.3 to 40 volume percent. Here, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 0.3 volume percent or more, more preferably 0.5 volume percent or more, and even more preferably 1 volume percent or more. Furthermore, from the viewpoint of ensuring that the viscosity of the electrolyte is within an appropriate range, that the decrease in ionic conductivity is suppressed, and that the output characteristics of the battery are within a good range, the above content is preferably 40 volume percent or less, more preferably 35 volume percent or less, and even more preferably 30 volume percent or less. Here, if two or more sulfone compounds are included, the above content refers to the total content of those compounds.

[0119] [1-4. Other Compounds] The non-aqueous electrolyte according to this embodiment may contain other compounds other than the electrolyte, non-aqueous solvent, and the compound having a Si-F bond, to the extent that it does not significantly impair the effects of the present invention.

[0120] Other compounds include, for example, unsaturated cyclic carbonates, fluorine-containing cyclic carbonates, isocyanate group-containing organic compounds, isocyanuric acid skeleton-containing organic compounds, sulfur-containing organic compounds, phosphorus-containing organic compounds, silicon-containing compounds, aromatic compounds, cyano group-containing organic compounds, acid anhydride compounds, and triple bond-containing compounds. These other compounds may be used individually or in any ratio and combination of two or more. Other compounds that improve low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics are preferably unsaturated cyclic carbonates, fluorine-containing cyclic carbonates, isocyanate group-containing organic compounds, isocyanuric acid skeleton-containing organic compounds, sulfur-containing organic compounds, phosphorus-containing organic compounds, silicon-containing compounds, aromatic compounds, cyano group-containing organic compounds, acid anhydride compounds, and triple bond-containing compounds. Unsaturated cyclic carbonates, fluorine-containing cyclic carbonates, isocyanate group-containing organic compounds, and isocyanuric acid skeleton-containing organic compounds are more preferred, and unsaturated cyclic carbonates and fluorine-containing cyclic carbonates are even more preferred.

[0121] The total content of other compounds in the non-aqueous electrolyte according to this embodiment is preferably 0.1 to 20% by mass. Here, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the total content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the content is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. In this specification, the identification of other compounds and the content of other compounds are measured by nuclear magnetic resonance (NMR) analysis. If it is difficult to identify other compounds or measure the content of other compounds by nuclear magnetic resonance (NMR) analysis alone, other analyses such as infrared spectroscopy (IR) analysis and gas chromatography-mass spectrometry may be used in combination.

[0122] [1-4-1. Unsaturated Cyclic Carbonates] Examples of unsaturated cyclic carbonates that can be used as other compounds in this embodiment include vinylene carbonates; ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds; phenyl carbonates; vinyl carbonates; allyl carbonates; catechol carbonates, etc. Unsaturated cyclic carbonates may be used individually or two or more in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, vinylene carbonates and ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds are preferred, and vinylene carbonates are more preferred.

[0123] 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-vinyl vinylene carbonate, allyl vinylene carbonate, and 4,5-diallyl vinylene carbonate. Vinylene carbonates may be used individually or in any ratio and combination of two or more types.

[0124] Examples of ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds include vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5-ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, and 4-methyl-5-allylethylene carbonate. Ethylene carbonates substituted with substituents having aromatic rings, carbon-carbon double bonds, or carbon-carbon triple bonds may be used individually or in any ratio and combination of two or more types.

[0125] From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are preferred as unsaturated cyclic carbonates, vinylene carbonate and vinylethylene carbonate are more preferred, and vinylene carbonate is even more preferred.

[0126] [1-4-2. Fluorine-containing cyclic carbonates] Other fluorine-containing cyclic carbonates that can be used as compounds in this embodiment include, for example, fluorinated cyclic carbonates having alkylene groups with 2 to 6 carbon atoms, such as fluorinated ethylene carbonate; and derivatives of fluorinated cyclic carbonates having alkylene groups with 2 to 6 carbon atoms, such as fluorinated ethylene carbonate substituted with alkyl groups with 1 to 4 carbon atoms. One type of fluorine-containing cyclic carbonate may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, fluoroethylene carbonates with 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates with 1 to 8 fluorine atoms, and ethylene carbonates having fluorine-containing groups are preferred as fluorine-containing cyclic carbonates.

[0127] Examples of fluoroethylene carbonates having 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates having 1 to 8 fluorine atoms, and ethylene carbonates having a fluorine-containing group include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, and 4,4-difluoro-5-methylethylene Examples include ethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate, etc. Fluoroethylene carbonates with 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates with 1 to 8 fluorine atoms, and ethylene carbonates having a fluorine-containing group may be used individually or in any ratio and combination of two or more types. Of the fluoroethylene carbonates having 1 to 4 fluorine atoms, derivatives of fluoroethylene carbonates having 1 to 8 fluorine atoms, and ethylene carbonates having a fluorine-containing group, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferred from the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics.

[0128] [1-4-3. Organic Compounds Containing Isocyanate Groups] In this embodiment, the number of isocyanate groups in the other compounds containing isocyanate groups is preferably 1 to 4, more preferably 2 to 3, and even more preferably 2, from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics.

[0129] Examples of isocyanate group-containing organic compounds include monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, butyl isocyanate, vinyl isocyanate, propargyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate; and diisocyanate compounds such as monomethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylenediisocyanate, 1,3-diisocyanatopropane, 1,3-bis(isocyanatomethyl)cyclohexane, carbonyl diisocyanate, and 1,4-diisocyanato-2-fluorobutane. The isocyanate group-containing organic compounds may be used individually or in any ratio and combination of two or more. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, diisocyanate compounds are preferred among isocyanate group-containing organic compounds, hexamethylene diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane are more preferred, and 1,3-bis(isocyanatomethyl)cyclohexane is even more preferred.

[0130] [1-4-4. Organic Compounds Containing an Isocyanuric Acid Skeleton] Examples of organic compounds containing an isocyanuric acid skeleton that can be used as other compounds in this embodiment include the following compounds.

[0131]

[0132] The isocyanuric acid skeleton-containing organic compound may be used alone or two or more in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, isocyanurate compounds having saturated or unsaturated aliphatic hydrocarbon groups which may have halogen atoms are preferred, isocyanurate compounds having unsaturated aliphatic hydrocarbon groups with a carbon-carbon unsaturated bond at the terminal are more preferred, and triallyl isocyanurate is even more preferred.

[0133] [1-4-5. Sulfur-containing organic compounds] In this embodiment, the sulfur-containing organic compounds that are other compounds are preferably organic compounds having at least one S=O bond, from the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, and more preferably linear sulfonic acid esters, cyclic sulfonic acid esters, linear sulfate esters, cyclic sulfate esters, linear sulfite esters, and cyclic sulfite esters.

[0134] Examples of sulfur-containing organic compounds include methyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, propargyl methanesulfonate, busulfan, methyl methanesulfonyloxyacetate, methyl vinylsulfonate, allyl vinylsulfonate, propargyl allylsulfonate, methoxycarbonylmethyl methanedisulfonate, ethoxycarbonylmethyl methanedisulfonate, methoxycarbonylmethyl 1,3-butanedisulfonate, ethoxycarbonylmethyl 1,3-butanedisulfonate, and 1,3-butanedisulfonate. Chain-like sulfonic acid esters such as alkyl disulfonic acid esters like 1-methoxycarbonylethyl phosphate, 1-ethoxycarbonylethyl 1,3-butanedisulfonic acid, and hexafluorophenyl methanesulfonic acid; 1,3-propanesultone, 1-fluoro-1,3-propanesultone, 1-methyl-1,3-propanesultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 1,3-butanesultone, 2, Cyclic sulfonic acid esters such as 4-butanesultone, 1,4-butanesultone, 1,5-pentanesultone, methylenemethanedisulfate, ethylenemethanedisulfate, and 2,2-dioxide-1,2-oxathiolan-4-ylacetate; linear sulfuric acid esters such as dimethyl sulfate, ethylmethyl sulfate, and diethyl sulfate; 1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, and 2,4,8,10-tetraoxa-3,9-dithia Cyclic sulfuric acid esters such as spiro[5,5]undecane-3,3,9,9-tetraoxide; linear sulfite esters such as dimethyl sulfite, ethyl methyl sulfite, and diethyl sulfite; cyclic sulfite esters such as 1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, and 1,2-butylene sulfite; cyclic sulfones such as 1,1-dioxidetetrahydrothiophene-3-ylmethanesulfonate and 1,1-dioxide-2,3-dihydrothiophene-3-ylmethanesulfonate;Examples include sulfonic acid esters such as butane-2,3-diylmethanesulfonate, butane-1,4-diylmethanesulfonate, and methylenemethanedisulfonate; and vinyl sulfones such as divinylsulfone, 2-bis(vinylsulfonyl)ethane, and bis(2-vinylsulfonylethyl) ether. The sulfur-containing organic compound may be used individually or in any ratio and combination of two or more. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, linear sulfonic acid esters, cyclic sulfonic acid esters, and cyclic sulfite esters are preferred, cyclic sulfonic acid esters and cyclic sulfite esters are more preferred, and 1,3-propanesultone, methylenemethanedisulfonate, and 1,2-ethylenesulfate are even more preferred.

[0135] [1-4-6. Phosphorus-containing organic compounds] Examples of phosphorus-containing organic compounds that can be used as other compounds in this embodiment include trimethyl phosphate, tributyl phosphate, trioctyl phosphate, trippropargyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, ethyl-2-(diethoxyphosphoryl) acetate, 2-propynyl-2-(diethoxyphosphoryl) acetate, methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, ethoxyheptafluorocyclotetraphosphazene, and the like. A single phosphorus-containing organic compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, trimethyl phosphate, tributyl phosphate, and trioctyl phosphate are preferred as phosphorus-containing organic compounds, with trimethyl phosphate being more preferred.

[0136] [1-4-7. Silicon-containing compounds] Other silicon-containing compounds in this embodiment include, for example, borate compounds such as tris(trimethylsilyl) borate, tris(trimethoxysilyl) borate, tris(triethylsilyl) borate, and tris(dimethylvinylsilyl) borate; phosphoric acid compounds such as tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(triphenylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and tris(dimethylvinylsilyl) phosphate; tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(triphenylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and tris(trimethylsilyl) phosphate. Examples include phosphorous acid compounds such as dimethylvinylsilyl; sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate; silane compounds such as tetramethylsilane, trimethylvinylsilane, dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane; disilane compounds such as hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, and 1,2-diphenyltetramethyldisilane; and disiloxane compounds such as hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, and 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane. However, the silicon-containing compounds listed above do not include compounds having Si-F bonds. Silicon-containing compounds may be used individually or in any ratio and combination of two or more. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, disilane compounds and disiloxane compounds are preferred as silicon-containing compounds, disiloxane compounds are more preferred, hexamethyldisiloxane and 1,3-divinyltetramethyldisiloxane are even more preferred, and 1,3-divinyltetramethyldisiloxane is particularly preferred.

[0137] [1-4-8. Aromatic Compounds] Examples of aromatic compounds that can be used as other compounds in this embodiment include cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, 1-fluoro-4-tert-butylbenzene, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, fluorobenzene, methylphenyl carbonate, ethylphenyl carbonate, diphenyl carbonate, etc. Aromatic compounds may be used individually or two or more in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, fluorobenzene, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene are preferred, and biphenyl, o-terphenyl, fluorobenzene, cyclohexylbenzene, and tert-amylbenzene are more preferred.

[0138] [1-4-9. [Cyano Group-Containing Organic Compounds] Other cyano group-containing organic compounds in this embodiment include, for example, monocyano compounds such as acetonitrile, propionitrile, butyronitrile, pentanenitrile, hexanenitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclohexanecarbonitride, acrylonitrile, methacrylonitrile, and crotononitrile; dicyano compounds such as succinonitrile, glutalonitrile, adiponitrile, pimeronitrile, suberonitrile, sebaconitrile, methylmalononitrile, ethylmalononitrile, bicyclohexyl-1,1-dicarbonitride, 1,4-dicyanopentane, and 1,2-didianobenzene; and tricyano compounds such as 1,2,3-propanetricarbonitride, 1,2,3-tris(2-cyanoethoxy)propane, 1,3,6-hexanetricarbonitride, 1,3,5-cyclohexanetricarbonitride, and 1,3,5-benzenetricarbonitride. The cyano group-containing organic compound may be used alone or two or more in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, dicyano compounds are preferred, succinonitrile and adiponitrile are more preferred, and adiponitrile is even more preferred.

[0139] [1-4-10. Acid anhydride compounds] Examples of other acid anhydride compounds in this embodiment include chain-like carboxylic acid anhydrides such as acetic anhydride, acrylic anhydride, methacrylic anhydride, cyclohexanecarboxylic acid anhydride, propic acid anhydride, benzoic acid anhydride, fluoroacetic acid anhydride, 4-fluorobenzoic acid anhydride, and propionic acetate anhydride, as well as succinic anhydride, maleic anhydride, citraconic acid anhydride, glutaric acid anhydride, itaconic acid anhydride, fluorosuccal anhydride, allyl succinic acid anhydride, 1,2-oxathiolan-5-one = 2,2-dioxide, and 1,2,6-oxadithiane = 2,2,6,6-tetraoxide. One acid anhydride compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, methacrylic anhydride, succinic anhydride, maleic anhydride, and allyl succinic anhydride are preferred as acid anhydride compounds, with succinic anhydride and allyl succinic anhydride being more preferred.

[0140] [1-4-11. Triple Bond-Containing Compounds] Examples of triple bond-containing compounds that can be used as other compounds in this embodiment include 2-propynylmethyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonic acid, 2-propynyl vinylsulfonic acid, 2-propynyl 2-(methanesulfonyloxy)propionic acid, di(2-propynyl)oxalate, 2-butyne-1,4-diylmethanesulfonate, 2-butyne-1,4-diyldiformate, 1H-imidazole-1-carboxylic acid propargyl, and the like. A single triple bond-containing compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving low-temperature power characteristics, high-rate charge-discharge characteristics, impedance characteristics, high-temperature storage characteristics, and cycle characteristics, the triple bond-containing compounds are preferably 2-propynylmethyl carbonate, 2-propynyl methacrylate, 2-propynyl methanesulfonic acid, 2-propynyl vinylsulfonic acid, di(2-propynyl)oxalate, and 2-butyne-1,4-diylmethanesulfonate, and more preferably 2-propynyl methanesulfonic acid, 2-propynyl vinylsulfonic acid, di(2-propynyl)oxalate, and 2-butyne-1,4-diylmethanesulfonate.

[0141] [1-5. Method for Producing Electrolyte] The method for producing the electrolyte according to this embodiment uses PF as the constituent anion. ６ The process includes at least one of the following steps: dissolving an electrolyte containing an anion and a sulfonylimide anion, and a compound having an Si-F bond, in a non-aqueous solvent; and adding a raw material for the compound having an Si-F bond to a solution containing a non-aqueous solvent to generate the compound having an Si-F bond in the solution. However, from the viewpoint of improving the gas generation suppression effect when the electrolyte is used in a battery, the constituent anion is PF ６ A preferred step is to dissolve an electrolyte containing an anion and a sulfonylimid anion, and a compound having a Si-F bond, in a non-aqueous solvent. The constituent anion is PF ６The timing of adding the electrolyte containing the anion and the sulfonylimid anion is arbitrary in any step. For example, in the step of dissolving a compound having an Si-F bond in a non-aqueous solvent, the electrolyte may be dissolved in the non-aqueous solvent first, and then the compound having the Si-F bond may be dissolved. Alternatively, when dissolving the raw material for a compound having an Si-F bond in a non-aqueous solvent, the electrolyte may be added to and dissolved in the non-aqueous solvent first, and then the raw material for the compound having the Si-F bond may be dissolved in the non-aqueous solvent to generate the compound having the Si-F bond.

[0142] Furthermore, the method for producing the electrolyte according to this embodiment uses PF as a constituent anion. ６ The process also includes a step of dissolving an electrolyte containing an anion and a sulfonylimid anion, but the constituent anion is PF ６ The steps of dissolving an electrolyte containing anions and dissolving an electrolyte containing sulfonylimide anions as constituent anions may be performed simultaneously, sequentially, or separately, and the results may be mixed. Alternatively, the electrolyte raw materials may be dissolved in a non-aqueous solvent, and the electrolyte may be generated in the electrolyte solution, i.e., PF ６ The process may include a step of generating an anion or a sulfonylimid anion.

[0143] The compounds having Si-F bonds in the method for producing a non-aqueous electrolyte according to this embodiment are described in the same way as the compounds having Si-F bonds in [1-1. Compounds Having Si-F Bonds] above, and the preferred embodiments are also the same.

[0144] The electrolyte in the method for producing a non-aqueous electrolyte according to this embodiment is described in the same way as the electrolyte in [1-2. Electrolytes] above, and the preferred embodiment is also the same. That is, the constituent anion is PF ６ The specific embodiments of the anions, sulfonylimide anions, and compounds containing these anions are as described in [1-2. Electrolytes] above.

[0145] The non-aqueous solvent in the method for producing the electrolyte according to this embodiment is described in the same way as the non-aqueous solvent in [1-3. Non-aqueous solvent] above, and the preferred embodiments are also the same.

[0146] Compounds having an Si-F bond, and PF as a constituent anion. ６ The method for dissolving electrolytes containing anions and sulfonylimid anions in a non-aqueous solvent is not particularly limited, and the compound having an Si-F bond and the constituent anion being PF ６ The compounds (salts) containing anions and compounds (salts) containing sulfonylimidone anions as constituent anions may be prepared by sequentially dissolving each in a non-aqueous solvent, or by sequentially mixing each compound (salt) dissolved in a non-aqueous solvent at high concentrations into a non-aqueous solvent.

[0147] [2. Battery] The battery according to this embodiment includes a positive electrode, a negative electrode, and a non-aqueous electrolyte.

[0148] [2-1. Non-aqueous electrolyte] The non-aqueous electrolyte in this embodiment is described in the same way as the electrolyte described in [1. Non-aqueous electrolyte] above, and the preferred embodiment is also the same. The non-aqueous electrolyte may be used in combination with an electrolyte other than the non-aqueous electrolyte described above, as long as it does not significantly impair the effects of the present invention.

[0149] [2-2. Positive Electrode] In this embodiment, the positive electrode includes positive electrode active material in at least a portion of the surface of the current collector.

[0150] [2-2-1. Positive Electrode Active Material] The positive electrode active material in this embodiment is not particularly limited as long as it is capable of electrochemically intercalating and releasing metal ions. Examples of positive electrode active materials include lithium transition metal compounds, sodium transition metal compounds, potassium transition metal compounds, etc. The positive electrode active material may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of increasing the energy density of the battery, lithium transition metal compounds, sodium transition metal compounds, and potassium transition metal compounds are preferred as positive electrode active materials, and lithium transition metal compounds are more preferred.

[0151] [2-2-1-1. Lithium Transition Metal Compounds] The lithium transition metal compound that serves as the positive electrode active material in this embodiment is not particularly limited as long as it is a compound having a structure that allows for insertion, removal, and insertion of lithium ions. Examples of lithium transition metal compounds include lithium transition metal sulfides, lithium transition metal phosphate compounds, lithium transition metal silicate compounds, lithium transition metal borate compounds, and lithium transition metal composite oxides. One lithium transition metal compound may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of increasing the energy density of the battery, lithium transition metal phosphate compounds and lithium transition metal composite oxides are preferred, and lithium transition metal composite oxides are more preferred.

[0152] Examples of lithium transition metal composite oxide structures include spinel structures, olivine structures, and layered structures. From the viewpoint of battery capacity and durability, spinel structures, olivine structures, and layered structures are preferred for lithium transition metal composite oxides, and from the viewpoint of increasing battery capacity, layered structures are more preferred.

[0153] Lithium transition metal composite oxides having a spinel structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (I).

[0154]

[0155] (0.8≦a in compositional formula (I) １ ≤ 1.5, 1.9 ≤ b １ ≤ 2.1, M １ (It contains at least one transition metal element, excluding Li.)

[0156] M １ Examples include Ni, Co, Mn, V, Al, etc. １ One type may be used alone, or two or more types may be used in any ratio and combination. １ From the viewpoint of improving the battery's cycle performance, Ni, Co, and Mn are preferred, and Ni and Mn are more preferred.

[0157] Examples of lithium transition metal composite oxides having a spinel structure include LiMn ２ O ４ LiCoMnO ４ LiNi ０．５ Mn １．５ O ４ LiCoVO ４ Examples include LiMn. A lithium transition metal composite oxide having a spinel structure may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving the battery cycle performance, LiMn ２ O ４ LiNi ０．５ Mn １．５ O ４ LiNi ０．５ Mn １．５ O ４ This is preferable.

[0158] Lithium transition metal composite oxides having an olivine structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (II).

[0159]

[0160] (0.8≦a in compositional formula (II) ２ ≤ 1.5, 0.9 ≤ b ２ ≤ 1.1, M ２ (It contains at least one transition metal element, excluding Li.)

[0161] M ２ Examples include Fe, Ni, Co, Mn, Al, etc. ２ One type may be used alone, or two or more types may be used in any ratio and combination. ２ From the viewpoint of improving the battery's cycle performance, Fe, Ni, Co, and Mn are preferred, with Fe and Mn being more preferred.

[0162] Examples of lithium transition metal composite oxides having an olivine structure include LiFePO ４Examples include the following. A lithium transition metal composite oxide having an olivine structure may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of improving the battery cycle performance, the lithium transition metal composite oxide having an olivine structure is LiFePO ４ It is preferable.

[0163] Lithium transition metal composite oxides having a layered structure allow for three-dimensional diffusion of lithium ions and are generally represented by the following compositional formula (III).

[0164]

[0165] (0.8≦a in compositional formula (III) ３ ≤ 1.5, 0.5 ≤ b ３ ≤ 1.1, M ３ (It contains at least one transition metal element, excluding Li.)

[0166] M ３ Examples include Ni, Co, Mn, Al, Mg, Zr, Fe, Ti, Er, etc. ３ One type may be used alone, or two or more types may be used in any ratio and combination. ３ From the viewpoint of improving the battery's cycle performance, Ni, Co, Mn, Al, Mg, and Zr are preferred, and Ni, Co, Mn, and Al are more preferred.

[0167] Examples of lithium transition metal composite oxides having a layered structure include LiCoO ２ LiNiO ２ LiNi ０．９ Co ０．０５ Mn ０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ Co ０．１５ Al ０．０５ O ２ LiNi ０．３３ Co ０．３３ Mn ０．３３ O ２ Li １．０５ Ni ０．３３Co ０．３３ Mn ０．３３ O ２ LiNi ０．５ Co ０．３ Mn ０．２ O ２、 LiNi ０．５ Co ０．２ Mn ０．３ O ２ Li １．０５ Ni ０．５ Co ０．２ Mn ０．３ O ２ LiNi ０．６ Co ０．２ Mn ０．２ O ２ LiNi ０．８ Co ０．１ Mn ０．１ O ２ , Li[Li １／３ Mn ２／３ ]O ２ Examples include solid solutions thereof. A lithium transition metal composite oxide having a layered structure may be used alone, or two or more may be used in any ratio and combination.

[0168] From the viewpoint of increasing battery capacity, lithium transition metal composite oxides having a layered structure are preferred if they are represented by the following compositional formula (IV), and more preferably if they are represented by the following compositional formula (V).

[0169]

[0170] (0.8≦a in compositional formula (IV) ４ ≤ 1.1, 0.3 ≤ b ４ ≤0.98, 0.0 ≤c ４ ≤ 0.7, 0.9 ≤ b ４ +c ４ ≤ 1.1, M ４ (This is at least one metallic element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er.)

[0171]

[0172] (0.8≦a in compositional formula (V) ５ ≤ 1.1, 0.3 ≤ b ５≤0.98, 0.01 ≤c ５ ≤0.7, 0.01 ≤d ５ ≤ 0.6, 0.9 ≤ b ５ +c ５ +d ５ ≤ 1.1, M ５ (This is at least one metallic element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er.)

[0173] M in the composition formula (IV) ４ This element is at least one metal element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er. From the viewpoint of improving the structural stability of lithium transition metal oxides and suppressing structural degradation during repeated charging and discharging, Co, Mn, and Al are preferred, and Co and Mn are more preferred.

[0174] b in the empirical formula (IV) ４ b is 0.3 or higher, and from the viewpoint of improving the battery's cycle performance, 0.4 or higher is preferable, and 0.5 or higher is more preferable. ４ The value is 0.98 or less, and from the viewpoint of battery safety, 0.97 or less is preferred, and 0.96 or less is more preferred.

[0175] Examples of lithium transition metal composite oxides represented by compositional formula (IV) include LiNi ０．９ Co ０．０５ Mn ０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ Co ０．１５ Al ０．０５ O ２ LiNi ０．３ Co ０．３ Mn ０．３ O ２ LiNi ０．５ Co ０．２ Mn ０．３ O ２ Li １．０５ Ni ０．５ Co ０．２ Mn ０．３ O ２ LiNi ０．６ Co０．２ Mn ０．２ O ２ LiNi ０．８ Co ０．１ Mn ０．１ O ２ LiNi ０．９１ Co ０．０６ Mn ０．０３ O ２ LiNi ０．９１ Co ０．０６ Al ０．０３ O ２ LiNi ０．９ Co ０．０３ Al ０．０７ O ２ LiNi ０．６１ Co ０．２ Mn ０．１９ O ２ Examples include the following. The lithium transition metal composite oxide represented by compositional formula (IV) may be used alone, or two or more may be used in any ratio and combination.

[0176] M in the composition formula (V) ５ This element is at least one metal element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er. From the viewpoint of improving the structural stability of lithium transition metal oxides and suppressing structural degradation during repeated charging and discharging, Mn and Al are preferred, and Mn is more preferred.

[0177] b in the empirical formula (V) ５ b is 0.3 or higher, preferably 0.4 or higher, and more preferably 0.5 or higher, from the viewpoint of increasing the energy density of the battery. ５ The value is 0.98 or less, and from the viewpoint of battery safety, 0.97 or less is preferred, and 0.96 or less is more preferred.

[0178] d in the empirical formula (V) ５ It is 0.01 or greater, and from the viewpoint of battery safety, 0.1 or greater is preferred. Also, d ５ The value is 0.6 or less, and from the viewpoint of increasing the energy density of the battery, 0.5 or less is preferable.

[0179] Examples of lithium transition metal composite oxides represented by compositional formula (V) include LiNi ０．９ Co ０．０５Mn ０．０５ O ２ LiNi ０．８５ Co ０．１ Al ０．０５ O ２ LiNi ０．８ Co ０．１５ Al ０．０５ O ２ LiNi ０．３ Co ０．３ Mn ０．３ O ２ LiNi ０．５ Co ０．２ Mn ０．３ O ２ Li １．０５ Ni ０．５ Co ０．２ Mn ０．３ O ２ LiNi ０．６ Co ０．２ Mn ０．２ O ２ LiNi ０．８ Co ０．１ Mn ０．１ O ２ LiNi ０．９１ Co ０．０６ Mn ０．０３ O ２ LiNi ０．９１ Co ０．０６ Al ０．０３ O ２ LiNi ０．９ Co ０．０３ Al ０．０７ O ２ LiNi ０．６１ Co ０．２ Mn ０．１９ O ２ Examples include the following. The lithium transition metal composite oxide represented by compositional formula (V) may be used alone, or two or more may be used in any ratio and combination.

[0180] The lithium transition metal composite oxide may further contain elements other than those included in the aforementioned compositional formulas (I) to (V) (other elements).

[0181] [2-2-1-2. Surface Coating] In this embodiment, the positive electrode active material may be one in which a substance with a different composition from the positive electrode active material (surface-adhered substance) is attached to the surface of the positive electrode active material. Examples of surface-adhered substances include oxides such as aluminum oxide; sulfates such as lithium sulfate; and carbonates such as lithium carbonate. One type of surface-adhered substance may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of battery safety, lithium carbonate is preferred as the surface-adhered substance. The surface-adhered substance can be attached to the surface of the positive electrode active material by dissolving it in a solvent or dispersing it in a dispersion medium and impregnating the positive electrode active material with it.

[0182] The content of surface-adhered material relative to the total positive electrode active material is preferably 1 μmol / g or more and 1 mmol / g or less. Here, from the viewpoint of battery safety, the above content is preferably 1 μmol / g or more, and more preferably 10 μmol / g or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 1 mmol / g or less, and more preferably 0.5 mmol / g or less. In this specification, surface-adhered material attached to the surface of the positive electrode active material is also included in the positive electrode active material.

[0183] [2-2-2. Method for Manufacturing the Positive Electrode] Examples of methods for manufacturing the positive electrode in this embodiment include a method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by pressure bonding, and a method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating. From the viewpoint of a simple manufacturing process and excellent productivity, the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating is preferred.

[0184] The positive electrode active material layer further includes a positive electrode active material and a binder, as well as, if necessary, a conductive material and a thickening agent.

[0185] In the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by pressure bonding, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a positive electrode active material and binder, as well as conductive material and thickener as needed, are dry-mixed to form a sheet, and then pressure-bonded onto a positive electrode current collector to obtain the positive electrode.

[0186] In the method of obtaining a positive electrode by forming a positive electrode active material layer on a current collector by coating, a method is preferred from the viewpoint of simplicity of the manufacturing process and excellent productivity, in which, in addition to the positive electrode active material and binder, a conductive material and a thickener are further dissolved in a solvent or dispersed in a dispersion medium as needed, and the mixture is coated onto the positive electrode current collector and dried to obtain the positive electrode.

[0187] [2-2-2-1. Positive Electrode Active Material Layer] The content of positive electrode active material in the positive electrode active material layer is preferably 80 to 99.5% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 80% by mass or more, and more preferably 90% by mass or more. Also, from the viewpoint of improving the handling of the positive electrode, the above content is preferably 99.5% by mass or less, and more preferably 99% by mass or less. Here, if two or more types of positive electrode active materials are included, the above content refers to the total content of those materials. In this specification, the identification of positive electrode active material and the content of positive electrode active material are measured by high-frequency inductively coupled plasma (ICP) emission spectroscopy after wet decomposition of the sample. If it is difficult to identify positive electrode active material or determine the content of positive electrode active material by high-frequency inductively coupled plasma (ICP) emission spectroscopy alone, other analyses such as X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF) analysis, and energy-dispersive X-ray spectroscopy (EDS) analysis may be used in combination.

[0188] Examples of binders include fluororesins such as polyvinyl fluoride, polyvinylidene fluoride, and polytetrafluoroethylene; cyano group-containing resins such as polyacrylonitrile and polyvinylidene cyanide; and modified versions thereof, derivatives, random copolymers, alternating copolymers, graft copolymers, and block copolymers. One binder may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of weather resistance, chemical resistance, heat resistance, and flame retardancy, fluororesins and cyano group-containing resins are preferred as binders.

[0189] When a resin is used as a binder, the weight-average molecular weight of the resin is preferably 10,000 to 3,000,000. Here, from the viewpoint of improving the strength of the positive electrode, the weight-average molecular weight is preferably 10,000 or more, more preferably 50,000 or more, and even more preferably 100,000 or more. Furthermore, from the viewpoint of ease of forming the positive electrode, the weight-average molecular weight is preferably 3,000,000 or less, more preferably 950,000 or less, and even more preferably 900,000 or less.

[0190] The binder content in the positive electrode active material layer is preferably 0.1 to 20% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0191] Examples of conductive materials include metallic materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbon-based materials such as amorphous carbon such as needle coke. One type of conductive material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of enhancing conductivity, carbon black is preferred as the conductive material.

[0192] When the positive electrode active material layer contains a conductive material, the content of the conductive material in the positive electrode active material layer is preferably 0.01 to 15% by mass. Here, from the viewpoint of increasing conductivity, the above content is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0193] From the viewpoint of increasing the packing density of the positive electrode active material, it is preferable to compact the positive electrode active material layer using a hand press, roller press, or the like. The density of the positive electrode active material layer is 1.5 to 4.5 g / cm³. ３ This is preferable. Here, from the viewpoint of increasing the energy density of the battery, the above density is 1.5 g / cm³. ３ The above is preferable, specifically 2.0 g / cm³. ３ The above is more preferable. Furthermore, from the viewpoint of impregnating with electrolyte, the density is 4.5 g / cm³.３ The following is preferable: 4.0 g / cm³ ３ The following are preferable.

[0194] The thickness of the positive electrode active material layer is preferably 10 to 500 μm. Here, from the viewpoint of increasing the energy density of the battery, the thickness is preferably 10 μm or more, and more preferably 15 μm or more. Also, from the viewpoint of improving the rate characteristics of the battery, the thickness is preferably 500 μm or less, and more preferably 300 μm or less. The positive electrode active material layer may be formed on one surface of the current collector, or on both surfaces of the current collector.

[0195] [2-2-2-2. Current Collector] Examples of materials for the current collector include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum. From the viewpoint of increasing the energy density of the battery, aluminum is preferred as the material for the current collector.

[0196] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. From the viewpoint of improving the handling of the positive electrode, metal foil and metal thin film are preferred as current collector shapes. The metal thin film may be formed in a mesh shape.

[0197] When the shape of the current collector is plate-shaped or film-shaped, the thickness of the current collector is preferably 1 μm or more and 1 mm or less. Here, from the viewpoint of improving the handling of the positive electrode, the above thickness is preferably 1 μm or more, and more preferably 2 μm or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above thickness is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0198] [2-2-3. Surface Coating of the Positive Electrode] The positive electrode may be one in which a substance with a different composition from the positive electrode active material (surface-adhered substance) is attached to the surface of the positive electrode. The same explanation as for the surface-adhered substance in [2-2-1-2. Surface Coating] applies to the surface-adhered substance on the surface of the positive electrode, and the preferred embodiments are also the same. In this specification, the surface-adhered substance attached to the surface of the positive electrode is also included in the positive electrode.

[0199] [2-3. Negative Electrode] In this embodiment, the negative electrode includes a negative electrode active material on at least a portion of the surface of the current collector.

[0200] [2-3-1. Negative Electrode Active Material] The negative electrode active material in this embodiment is not particularly limited as long as it is capable of electrochemically intercalating and releasing metal ions. Examples of negative electrode active materials include carbon-based materials and metal materials. The negative electrode active material may be used alone, or two or more may be used in any ratio and combination. From the viewpoint of cycle characteristics, continuous charging characteristics and safety, carbon-based materials, metal materials, and mixtures of carbon-based materials and metal materials are preferred as negative electrode active materials.

[0201] [2-3-1-1. Carbon-based materials] Examples of carbon-based materials that serve as the negative electrode active material in this embodiment include natural graphite such as uncoated natural graphite, amorphous carbon-coated natural graphite, graphite-coated natural graphite, and resin-coated natural graphite; artificial graphite; amorphous carbon, etc. One type of carbon-based material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of increasing battery capacity, natural graphite is preferred as the carbon-based material.

[0202] Examples of natural graphite include scaly natural graphite, flake-like natural graphite, and natural graphite obtained by treating these graphites with processes such as spheroidization or densification. Natural graphite may be used individually or in any ratio and combination of two or more types. From the viewpoint of packing properties and charge / discharge rate characteristics, spheroidized natural graphite is preferred.

[0203] [2-3-1-2. Physical Properties of Carbon-Based Materials] The d002 value (d value (interlayer distance) of the lattice plane (002 plane)) of carbon-based materials is theoretically 0.3354 nm or higher, and from the viewpoint of increasing battery capacity, it is preferably 0.3360 nm or lower, and more preferably 0.3357 nm or lower. In this specification, the d002 value is measured by X-ray diffraction according to the Japan Society for the Promotion of Science (JSPS) method.

[0204] The Lc (crystallite size) of carbon-based materials is preferably 0.9 nm or larger, and more preferably 1.0 nm or larger, from the viewpoint of increasing battery capacity. While there is no particular upper limit to the Lc (crystallite size), it is usually 500 nm or smaller. In this specification, the Lc value is measured by X-ray diffraction according to the Japan Society for the Promotion of Science (JSPS) method.

[0205] The average particle size of the carbon-based material is preferably 1 to 100 μm. Here, from the viewpoint of increasing battery capacity, the average particle size is preferably 1 μm or more, and more preferably 3 μm or more. Also, from the viewpoint of suppressing resistance, the average particle size is preferably 100 μm or less, and more preferably 50 μm or less. In this specification, the average particle size of particles such as carbon-based material is the volume-based average particle size (median diameter), and is measured by laser diffraction / scattering method.

[0206] The Raman R value of carbon-based materials is preferably 0.01 to 1.5. Here, from the viewpoint of suppressing resistance, the Raman R value is preferably 0.01 or higher, and more preferably 0.1 or higher. Furthermore, from the viewpoint of increasing battery capacity, the Raman R value is preferably 1.5 or lower, and more preferably 1 or lower. In this specification, the Raman R value is measured by argon ion laser Raman spectroscopy.

[0207] The Raman full width at half maximum (FWHM) for carbon-based materials is 10–100 cm. －１ This is preferable. Here, from the viewpoint of suppressing resistance, the above Raman half-width is 10 cm. －１ The above is preferable, 20 cm －１ The above is preferable. Also, from the viewpoint of increasing battery capacity, the above Raman half-width is 100 cm. －１ The following is preferable: 80 cm －１ The following is more preferable. In this specification, the Raman full width at half maximum is measured by argon ion laser Raman spectroscopy.

[0208] The specific surface area of ​​carbon-based materials ranges from 0.1 to 100 m². ２ / g is preferred. Here, from the viewpoint of suppressing resistance, the specific surface area is 0.1m². ２ Preferably 0.2 m ２ A value of 100 m² or more is more preferable. Furthermore, from the viewpoint of increasing battery capacity, the above specific surface area should be 100 m². ２ Preferably less than / g, and 50m ２ It is more preferable that the amount is less than or equal to / g. In this specification, the specific surface area is measured by the BET method.

[0209] [2-3-1-3. Metallic Material] The metallic material that serves as the negative electrode active material in this embodiment is a material containing a metallic element and / or a metalloid element that can be alloyed with an alkali metal. Furthermore, the metallic elements constituting the metallic material are metallic elements and / or metalloid elements.

[0210] Examples of metallic materials include metals such as Fe, Co, Sb, Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, V, Mn, As, Nb, Mo, Cu, Zn, Ge, In, Ti, and W; and compounds of these metals (metallic compounds). The metallic material may be used individually, in any ratio and combination of two or more metals, or as an alloy of two or more metals. Examples of metallic compounds include metal oxides, metal nitrides, and metal carbides. The metallic compound may be an oxide, nitride, or carbide of an alloy of two or more metals.

[0211] From the viewpoint of capacity and cycle life, the metallic material is preferably at least one metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn, and W, or a compound thereof, and from the viewpoint of high capacity, Si and Si compounds are more preferred. In this specification, Si and Si compounds are collectively referred to as Si-based materials.

[0212] Examples of Si compounds include Si oxides, Si nitrides, Si carbides, oxides of Si nitrides, and oxides of Si carbides (silicon oxycarbide). Si compounds may be used individually or in any ratio and combination of two or more types.

[0213] Si oxides are, for example, SiO ｘ１ It is expressed as, 0 < x １ <2 satisfies. Si nitrides are, for example, Si ３ N ４ SiN ｘ２ It is expressed as, 0 < x ２ The condition ≤ 1.3 is satisfied. Si carbides are, for example, SiC ｘ３ It is expressed as follows, and 0.9 ≤ x ３ The condition ≤ 1.1 is satisfied. Oxides of Si nitrides include, for example, SiN ｙ１ O ｚ１ It is expressed as follows, where 1 ≤ y１ ≤ 10, 0 < z １ The condition ≤ 1 is satisfied. Oxides of Si carbides include, for example, SiC ｙ２ O ｚ２ It is expressed as follows, where 1 ≤ y ２ ≤ 10, 0 < z ２ It satisfies ≤ 1.

[0214] Si-based materials include Si, Si oxide, and Si carbide oxides. Si is preferred because it allows for easy movement of alkali metal salts such as lithium ions, enabling high capacity. Si oxide is preferred because it has a larger theoretical capacity compared to graphite. Si carbide oxide is also preferred because it has a larger theoretical capacity compared to graphite.

[0215] When used in batteries that do not require high output performance, metal composite oxides are preferred as metal materials from the viewpoint of battery durability. Examples of metal composite oxides include Li ４／３ Ti ５／３ O ４ Li １ Ti ２ O ４ Li ４／５ Ti １１／５ O ４ Lithium titanium composite oxides such as Li ４／３ Ti ４／３ Al １／３ O ４ Examples include lithium titanium composite oxides in which part of lithium and / or titanium is replaced with other metals (e.g., Al, Ga, Cu, Zn, etc.). Metal composite oxides may be used individually or in any ratio and combination of two or more types. From the viewpoint of high current density charge / discharge characteristics, lithium titanium composite oxides and lithium titanium composite oxides in which part of lithium and / or titanium is replaced with other metals are preferred, and from the viewpoint of reducing output resistance, lithium titanium composite oxides having a spinel structure and lithium titanium composite oxides having a spinel structure in which part of lithium and / or titanium is replaced with other metals are more preferred. ４／３ Ti ５／３ O ４ Li １ Ti ２ O ４ Li４／５ Ti １１／５ O ４ Li ４／３ Ti ４／３ Al １／３ O ４ That is even more preferable.

[0216] When the metal material is in the form of particles, the average particle size of the metal particles is preferably 0.005 to 10 μm. Here, from the viewpoint of increasing battery capacity, the average particle size is preferably 0.005 μm or more, and more preferably 0.1 μm or more. Furthermore, from the viewpoint of suppressing resistance, the average particle size is preferably 10 μm or less, and more preferably 5 μm or less.

[0217] [2-3-1-4. Mixture of carbon-based material and metal material] The mixture of carbon-based material and metal material that serves as the negative electrode active material in this embodiment may be a mixture in which the carbon-based material and metal material are mixed in an independent state, or it may be a composite in which the metal material is present on the surface or inside the carbon-based material.

[0218] When a mixture of carbon-based material and metal material is used as the negative electrode active material, the content of the carbon-based material relative to the total negative electrode active material is preferably 1 to 95% by mass. Here, from the viewpoint of increasing the conductivity of the negative electrode, the above content is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

[0219] When a mixture of carbon-based material and metal material is used as the negative electrode active material, the content of the metal material relative to the total negative electrode active material is preferably 5 to 99% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. Furthermore, from the viewpoint of suppressing capacity loss during battery operation due to deterioration of the metal material, the above content is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 80% by mass or less.

[0220] [2-3-2. Method for Manufacturing the Negative Electrode] Examples of methods for manufacturing the negative electrode in this embodiment include a method of obtaining a positive electrode by forming a negative electrode active material layer on a current collector by pressure bonding, and a method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating. From the viewpoint of a simple manufacturing process and excellent productivity, the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating is preferred.

[0221] The negative electrode active material layer further includes, as necessary, a conductive material, a thickener, and a filler, in addition to the negative electrode active material and a binder.

[0222] In the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by pressure, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a negative electrode active material and binder, as well as conductive material, thickener, and filler as needed, are dry-mixed to form a sheet, and then pressure-bonded onto a negative electrode current collector to obtain the negative electrode.

[0223] In the method of obtaining a negative electrode by forming a negative electrode active material layer on a current collector by coating, a preferred method is one in which, from the viewpoint of a simple manufacturing process and excellent productivity, a slurry is obtained by coating the negative electrode current collector with a slurry in which a negative electrode active material and binder are dispersed in a dispersion medium, as needed, a conductive material, a thickener and a filler, and then drying it.

[0224] [2-3-2-1. Negative Electrode Active Material Layer] The content of negative electrode active material in the negative electrode active material layer is preferably 80 to 99.5% by mass. Here, from the viewpoint of increasing the energy density of the battery, the above content is preferably 80% by mass or more, and more preferably 90% by mass or more. Also, from the viewpoint of improving the handling of the negative electrode, the above content is preferably 99.5% by mass or less, and more preferably 99% by mass or less. Here, if two or more types of negative electrode active materials are included, the above content refers to the total content of those materials. In this specification, the identification of negative electrode active materials and the content of negative electrode active materials are measured by high-frequency inductively coupled plasma (ICP) emission spectroscopy after alkali fusion of the sample.

[0225] Examples of binders include rubbery polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluororubber, acrylonitrile-butadiene rubber (NBR), and ethylene-propylene rubber; and fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and tetrafluoroethylene-ethylene copolymer. A single binder may be used, or two or more binders may be used in any ratio and combination. From the viewpoint of battery durability, styrene-butadiene rubber is preferred as the binder.

[0226] The binder content in the negative electrode active material layer is preferably 0.1 to 20% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0227] When a rubbery polymer is used as the main component of the binder, the binder content in the negative electrode active material layer is preferably 0.1 to 5% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0228] When a fluorine-based polymer is used as the main component of the binder, the binder content in the negative electrode active material layer is preferably 1 to 15% by mass. Here, from the viewpoint of battery durability, the above content is preferably 1% by mass or more, and more preferably 2% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0229] Examples of conductive materials include carbon black such as acetylene black; and carbon-based materials such as amorphous carbon such as needle coke. One type of conductive material may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of enhancing conductivity, carbon black is preferred as the conductive material.

[0230] When the negative electrode active material layer contains a conductive material, the content of the conductive material in the negative electrode active material layer is preferably 0.01 to 15% by mass. Here, from the viewpoint of increasing conductivity, the above content is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 15% by mass or less, and more preferably 10% by mass or less.

[0231] Examples of thickening agents include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, and their salts. A single thickening agent may be used, or two or more may be used in any ratio and combination. From the viewpoint of battery durability, carboxymethylcellulose is preferred as the thickening agent.

[0232] When the negative electrode active material layer contains a thickening agent, the content of the thickening agent in the negative electrode active material layer is preferably 0.5 to 5% by mass. Here, from the viewpoint of battery durability, the above content is preferably 0.5% by mass or more, and more preferably 1% by mass or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above content is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0233] From the viewpoint of increasing the packing density of the negative electrode active material, it is preferable to compact the negative electrode active material layer using a hand press, roller press, or the like. The density of the negative electrode active material layer is 1.0 to 2.2 g / cm³. ３ This is preferable. Here, from the viewpoint of increasing the energy density of the battery, the above density is 1.0 g / cm³. ３ The above is preferable, 1.5 g / cm³ ３ The above is more preferable. Furthermore, from the viewpoint of impregnating with electrolyte, the density is 2.2 g / cm³. ３ The following is preferable: 2.0 g / cm³ ３ The following are preferable.

[0234] The thickness of the negative electrode active material layer is preferably 10 to 500 μm. Here, from the viewpoint of increasing the energy density of the battery, the thickness is preferably 10 μm or more, and more preferably 15 μm or more. Also, from the viewpoint of improving the rate characteristics of the battery, the thickness is preferably 500 μm or less, and more preferably 300 μm or less. The negative electrode active material layer may be formed on one surface of the current collector, or on both surfaces of the current collector.

[0235] [2-3-2-2. Current Collector] Examples of materials for the current collector include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is preferred as the material for the current collector because it does not alloy with alkali metals and is inexpensive.

[0236] Examples of current collector shapes include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. From the viewpoint of improving the handling of the negative electrode, metal foil and metal thin film are preferred as current collector shapes. The metal thin film may be formed in a mesh shape.

[0237] When the shape of the current collector is plate-shaped or film-shaped, the thickness of the current collector is preferably 1 μm or more and 1 mm or less. Here, from the viewpoint of improving the handling of the negative electrode, the above thickness is preferably 1 μm or more, and more preferably 2 μm or more. Furthermore, from the viewpoint of increasing the energy density of the battery, the above thickness is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0238] [2-3-3. Surface Coating of the Negative Electrode] The negative electrode may be one in which a substance with a different composition from the negative electrode active material (surface-adhered substance) is attached to the surface of the negative electrode. The surface-adhered substance on the surface of the negative electrode is described in the same way as the surface-adhered substance on the surface of the positive electrode in [2-2-3. Surface Coating of the Positive Electrode], and the preferred embodiments are also the same. In this specification, the surface-adhered substance attached to the surface of the negative electrode is also included in the negative electrode.

[0239] [2-4. Separator] In the battery according to this embodiment, it is preferable to interpose a separator between the positive electrode and the negative electrode to prevent short circuits. It is preferable to use a separator impregnated with a non-aqueous electrolyte.

[0240] The separator material can be any known material, as long as it does not significantly impair the effects of the present invention. The separator shape can be any known shape, as long as it does not significantly impair the effects of the present invention.

[0241] [2-5. Battery Design] [2-5-1. Electrode Group] The electrode group in this embodiment may be a stacked structure in which the positive electrode and the negative electrode are stacked with a separator in between, or a wound structure in which the positive electrode and the negative electrode are wound in a spiral shape with a separator in between.

[0242] The electrode group occupancy rate, that is, the volume ratio of the electrode group to the total internal volume of the battery, is preferably 40 to 90%. Here, from the viewpoint of increasing the energy density of the battery, the electrode group occupancy rate is preferably 40% or more, and more preferably 50% or more. Furthermore, from the viewpoint of impregnation with electrolyte, the electrode group occupancy rate is preferably 90% or less, and more preferably 80% or less.

[0243] [2-5-2. Current Collection Structure] In this embodiment, when the electrode group has a laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to a terminal, or a structure that reduces resistance by providing multiple terminals within the electrode, is preferably used. Furthermore, when the electrode group has a wound structure, a structure that reduces resistance by providing multiple lead structures to each electrode and bundling them to a terminal is preferably used.

[0244] [2-5-3. Protective Elements] Examples of protective elements include PTC (Positive Temperature Coefficient) elements whose resistance increases with heat generation due to excessive current, thermal fuses, thermistors, and current interruption valves that interrupt the current flowing through the circuit due to a rapid rise in internal pressure or temperature of the battery during abnormal heat generation. One type of protective element may be used alone, or two or more types may be used in any ratio and combination. From the viewpoint of battery safety, protective elements that do not operate under normal high-current use are preferred, but it is even more preferable to design the battery so that abnormal heat generation or thermal runaway does not occur even without protective elements.

[0245] [2-5-4. Outer casing] The battery according to this embodiment is typically constructed by housing the positive electrode, negative electrode, separator, and electrolyte inside an outer casing.

[0246] Examples of materials for the exterior include metals such as iron, aluminum, and aluminum alloys; and laminated films. From the viewpoint of weight reduction and cost, metals and laminated films are preferred for the exterior material, and from the viewpoint of pressure resistance for operating the current interruption valve, iron is more preferred.

[0247] When metal is used as the material for the exterior, the structure of the exterior may be a sealed structure formed by welding metals together using laser welding, resistance welding, or ultrasonic welding, or it may be a crimped structure using metal via a resin gasket.

[0248] Examples of exterior shapes include cylindrical, rectangular, laminated, coin-shaped, and large. From the viewpoint of increasing the energy density of the battery, cylindrical, rectangular, and laminated exteriors are preferred.

[0249] [2-6. Method for Manufacturing a Battery] The method for manufacturing a battery according to this embodiment includes the steps of housing the positive electrode and the negative electrode in an outer casing, and injecting the non-aqueous electrolyte according to this embodiment into the outer casing.

[0250] The same description as for the non-aqueous electrolyte described above in [2-1. Non-aqueous electrolyte] applies to the non-aqueous electrolyte, and the preferred embodiments are also the same. The non-aqueous electrolyte may be used in combination with other electrolytes as long as it does not significantly impair the effects of the present invention.

[0251] The positive electrode in the battery manufacturing method is described in the same way as the positive electrode of the battery described above in [2-2. Positive Electrode], and the preferred embodiment is also the same.

[0252] The negative electrode in the battery manufacturing method is described in the same way as the negative electrode of the battery described above in [2-3. Negative Electrode], and the preferred embodiment is also the same.

[0253] The same description as for the battery casing in the method of manufacturing the battery applies to the casing of the battery described above in [2-5-4. Casing], and the preferred embodiments are also the same.

[0254] The steps of housing the positive and negative electrodes in the outer casing and injecting the non-aqueous electrolyte into the outer casing can be performed in any order. However, from the viewpoint of impregnating the outer casing with the non-aqueous electrolyte, it is preferable to perform the step of injecting the non-aqueous electrolyte into the outer casing after the step of housing the positive and negative electrodes in the outer casing.

[0255] In the process of housing the positive electrode and negative electrode in an outer casing, it is preferable to house the separator together with the positive electrode and negative electrode in the outer casing from the viewpoint of simplifying the manufacturing process and improving productivity.

[0256] [2-7. Applications] From the viewpoint of being able to be used repeatedly for a variety of applications, the battery according to this embodiment is preferably a non-aqueous electrolyte secondary battery, more preferably an alkaline ion secondary battery, and even more preferably a lithium ion secondary battery.

[0257] The battery according to this embodiment can be used for various known applications. Specific examples of applications include, for example, laptop computers, pen-input computers, mobile computers, e-book players, mobile phones, portable fax machines, portable copiers, portable printers, portable audio players, mini video cameras, headphone stereos, video camcorders, LCD televisions, handheld vacuum cleaners, portable CDs, MiniDiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, strobes, cameras, household backup power supplies, business backup power supplies, load leveling power supplies, and renewable energy storage power supplies.

[0258] In particular, the battery according to this embodiment is excellent in suppressing gas generation and can be used safely, making it suitable for use in vehicles such as automobiles, motorcycles, mopeds, and bicycles, and especially suitable for use in automobiles. That is, the present invention also relates to vehicles including the above-mentioned battery.

[0259] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0260] Compounds The compounds used in this example and comparative example are shown below. [Non-aqueous electrolyte] Compound 1: 3-(fluorodimethylsilyl)propylmethyl carbonate

[0261]

[0262] Compound 2: 3-(difluoromethylsilyl)propylmethyl carbonate

[0263]

[0264] Compound 3: Fluorodimethyloctylsilane

[0265]

[0266] ・Electrolyte LiPF ６ : PF as a constituent anion ６ Compounds containing anions: LiFSI (Lithium Bis(Fluorosulfonyl)imide): Compounds containing the sulfonylimid anion (FSI anion) as a constituent anion; Non-aqueous solvents: Ethylene carbonate (EC), Ethyl methyl carbonate (EMC), Dimethyl carbonate (DMC); Other compounds: Vinylen carbonate (VC)

[0267] Examples 1-7 and Comparative Examples 1-7: Preparation of Non-Aqueous Electrolyte Under a dry argon atmosphere, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (volume ratio EC:EMC:DMC = 3:4:3) was prepared, and a thoroughly dried LiPF was added as the electrolyte. ６ A base electrolyte was prepared by dissolving and / or LiFSI to the molar concentrations shown in Table 1 below. Furthermore, 1.0 part by mass of vinylene carbonate (VC) was added to 100 parts by mass of the base electrolyte, and for Examples 1 to 7 and Comparative Examples 5 to 7, compounds 1 to 3 were added in the amounts (parts by mass) shown in Table 1 below to prepare each non-aqueous electrolyte.

[0268] 《Battery Manufacturing》 [Positive Electrode Manufacturing] Lithium transition metal composite oxide (LiNi) is used as the positive electrode active material. ０．８ Co ０．１ Mn ０．１ O ２90 parts by mass of ), 3 parts by mass of polyvinylidene fluoride as a binder, and 7 parts by mass of acetylene black as a conductive material were mixed in N-methylpyrrolidone using a disperser to obtain a slurry. The obtained slurry was applied to both sides of a current collector (aluminum foil with a thickness of 15 μm), dried, and the density was 3.0 g / cm³. ３ The positive electrode was obtained by pressing it in that manner.

[0269] [Manufacturing of the negative electrode] 98 parts by mass of natural graphite powder as the negative electrode active material, 1 part by mass (based on solid content) of aqueous styrene-butadiene rubber dispersion (styrene-butadiene rubber concentration 50% by mass) as a binder, and 1 part by mass (based on solid content) of aqueous carboxymethylcellulose sodium dispersion (carboxymethylcellulose sodium concentration 1% by mass) as a thickener were mixed using a disperser to obtain a slurry. The obtained slurry was applied to one side of a current collector (copper foil with a thickness of 10 μm), dried, and a density of 1.5 g / cm³ was obtained. ３ The negative electrode was obtained by pressing it in that manner.

[0270] [Battery Manufacturing] The positive and negative electrodes obtained above were laminated with a polypropylene separator in between to obtain an electrode group. The obtained electrode group was inserted into a laminate film bag made of aluminum (40 μm thick) with both sides coated with a resin layer, so that the terminals of the positive and negative electrodes protruded from the bag. Then, the non-aqueous electrolyte of each example or comparative example was injected into the bag, and it was vacuum sealed to manufacture a pouch-type battery.

[0271] [Pre-test charging and discharging] The battery prepared using the method described above was charged with a constant current of 0.05C (1C refers to the current value that takes 1 hour to charge or discharge; the same applies hereinafter) for 10 hours in a constant temperature bath at 25°C, and then discharged to 2.8V at 0.2C. Subsequently, constant current-constant voltage charging (hereinafter referred to as CC-CV charging) was performed at 0.2C to 4.1V. After that, aging was performed by holding the battery at 60°C for 24 hours, and then discharged to 2.8V at 0.2C at 25°C. Furthermore, initial conditioning was performed by CC-CV charging to 4.2V at 0.2C, and then discharged to 2.8V at 0.2C.

[0272] [Low-Temperature Cycle Test] In a -10°C constant temperature bath, the battery was CC-CV charged to 4.2V at 0.2C, and then discharged to 2.8V at 0.2C. The discharge capacity at this time was defined as the 0-cycle discharge capacity. CC-CV charging to 4.2V at 1C, followed by discharge to 2.8V at 1C, was performed 49 times, and CC-CV charging to 4.2V at 0.2C, followed by discharge to 2.8V at 0.2C, was performed once. This constituted one set (total of 50 cycles), and four sets (total of 200 cycles) of charge-discharge tests were conducted. The -10°C cycle retention rate was calculated from the discharge capacity at cycle 0 and the discharge capacity at cycle 200 using the following formula: "-10°C cycle retention rate (%)" = {"Discharge capacity at cycle 200" / "Discharge capacity at cycle 0"} × 100

[0273] Table 1 shows the content of electrolytes and compounds having Si-F bonds in each non-aqueous electrolyte, the content ratio expressed as [A] / [B], and the evaluation results of the low-temperature cycle test. In Table 1, "-" for electrolytes and compounds having Si-F bonds means that they were not added.

[0274]

[0275] Based on the above results, a non-aqueous electrolyte containing a compound having an Si-F bond, wherein the electrolyte has PF as a constituent anion. ６ It has been found that the inclusion of anions and sulfonylimide anions results in excellent low-temperature properties. In particular, PF ６ It can be seen that the molar concentrations of the anion and sulfonylimid anion satisfy the specific formula (I-1): 0.05 ≤ [A] / [B] < 1.00, which indicates particularly excellent low-temperature characteristics.

[0276] Specifically, when an electrolyte containing a sulfonylimid anion is added to Comparative Example 4, which does not contain a sulfonylimid anion as a constituent anion, as shown in Comparative Examples 1 to 3, no significant change in low-temperature characteristics is observed. Furthermore, as shown in Comparative Examples 5 and 7, when an electrolyte contains PF as a constituent anion, ６When at least one of the anion and the sulfonylimid anion is not present, adding a compound having a Si-F bond does not significantly change the low-temperature properties. In contrast, as shown in Comparative Examples 1 to 3, when the constituent anion is PF ６ By adding a compound having an Si-F bond to an electrolyte containing anions and sulfonylimid anions, the low-temperature properties were greatly improved, as shown in Examples 1 to 5. This effect was not observed in Comparative Example 6, where the content ratio value expressed as [A] / [B] was 0.02. Furthermore, in the system to which the compound having an Si-F bond was added, it was found that the effect of Examples 1 to 5, which added an electrolyte containing sulfonylimid anions, was significantly greater than that of Comparative Example 5. From the results of Examples 1, 6, and 7, it was found that the above effect correlated to some extent with the content of compound 1.

[0277] Furthermore, among Examples 1 to 3, where the content ratio value represented by [A] / [B] is 0.6, the compound having an Si-F bond is the compound represented by the aforementioned general formula (1), and R in general formula (1) １ R is a hydrocarbon group which may be substituted with a halogen atom, ３ Examples 1 and 3, in which the hydrocarbon group may be substituted with a halogen atom, showed particularly excellent low-temperature characteristics.

[0278] Furthermore, among Examples 1, 4, and 5, which contain Compound 1 as a compound having an Si-F bond, Example 1, which satisfies formulas (I-3): 0.50 ≤ [A] / [B] < 1.00 and (I-4): 0.55 ≤ [A] / [B] < 1.00, exhibits particularly excellent low-temperature characteristics.

[0279] [Reference Example] Using the non-aqueous electrolytes of Examples 1, 4-7 and Comparative Example 1, batteries were manufactured in the same manner, and pre-test charge-discharge was performed under the same conditions. Then, a high-temperature cycle test was performed under the following conditions.

[0280] [High-Temperature Cycle Test] In a 45°C constant temperature bath, the battery was CC-CV charged to 4.2V at 0.2C, and then discharged to 2.8V at 0.2C. The discharge capacity at this time was defined as the 0-cycle discharge capacity. CC-CV charging to 4.2V at 1C, followed by discharge to 2.8V at 1C, was performed 49 times, and CC-CV charging to 4.2V at 0.2C, followed by discharge to 2.8V at 0.2C, was performed once. This constituted one set (50 cycles), and four sets (200 cycles in total) of charge-discharge tests were conducted. The 45°C cycle retention rate was calculated from the discharge capacity at cycle 0 and the discharge capacity at cycle 200 using the following formula: "45°C cycle retention rate (%)" = {"Discharge capacity at cycle 200" / "Discharge capacity at cycle 0"} × 100

[0281] The evaluation results of the high-temperature cycle test described above are shown in Table 2. The results for the batteries using non-aqueous electrolytes in Examples 1, 4-7, and Comparative Example 1 are designated as Reference Examples 1, 4-7, and Reference Comparative Example 1, respectively. For comparison, the results of the low-temperature cycle test for Examples 1, 4-7, and Comparative Example 1 are also included in Table 2.

[0282]

[0283] From the above results, it can be seen that among the (Reference) Examples 1, 4 to 7 containing compound 1 as a compound having an Si-F bond, (Reference) Examples 1, 4, 6 and 7 satisfying formula (I-2): 0.20 ≤ [A] / [B] < 1.00 exhibit excellent high-temperature characteristics, and (Reference) Examples 1, 6 and 7 satisfying formula (I-3): 0.50 ≤ [A] / [B] < 1.00 or formula (I-4): 0.55 ≤ [A] / [B] < 1.00 exhibit particularly excellent characteristics. (Reference) Examples 6 and 7 showed high-temperature characteristics comparable to or better than (Reference) Examples 4 and 5, even with low compound 1 content of 0.5 parts by mass and 1.0 part by mass, respectively.

[0284] (Reference) From the results of Examples 1 and 4-7, it can be seen that, from the viewpoint of having an excellent balance between low-temperature and high-temperature characteristics, a non-aqueous electrolyte that satisfies formula (I-1) is preferred, a non-aqueous electrolyte that satisfies formula (I-2) is more preferred, and a non-aqueous electrolyte that satisfies formula (I-3) or formula (I-4) is particularly preferred.

[0285] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-179871, filed on 15 October 2024, the contents of which are incorporated herein by reference.

[0286] The battery according to this embodiment can be used in various known applications. Specific examples of applications include, for example, notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, portable fax machines, portable copiers, portable printers, portable audio players, small video cameras, headphone stereos, video camcorders, LCD televisions, handheld vacuum cleaners, portable CDs, MiniDiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, strobes, cameras, household backup power supplies, business backup power supplies, load leveling power supplies, and natural energy storage power supplies. The battery according to this embodiment also exhibits excellent cycle characteristics in low-temperature environments, making it suitable for use in vehicles such as automobiles, motorcycles, mopeds, and bicycles, and particularly suitable for use in automobiles.

Claims

1. A non-aqueous electrolyte containing an electrolyte, a non-aqueous solvent, and a compound having an Si-F bond, wherein the electrolyte has PF as a constituent anion. ６ It contains anions and sulfonylimid anions, and the molar concentration [A] of sulfonylimid anions in the non-aqueous electrolyte and PF in the non-aqueous electrolyte ６ A non-aqueous electrolyte in which the total molar concentration [B] of the anion and sulfonylimid anion satisfies the following equation (I-1): (I-1): 0.05 ≤ [A] / [B] < 1.00 2. The non-aqueous electrolyte according to claim 1, wherein [A] and [B] satisfy the following relationship (I-2): (I-2): 0.20 ≤ [A] / [B] < 1.00 3. The non-aqueous electrolyte according to claim 1, wherein [A] and [B] satisfy the following relationship (I-3): (I-3): 0.50 ≤ [A] / [B] < 1.00 4. The non-aqueous electrolyte according to claim 1, wherein [A] and [B] satisfy the following relationship (I-4): (I-4): 0.55 ≤ [A] / [B] < 1.00 5. The non-aqueous electrolyte according to claim 1, wherein the compound having the Si-F bond includes a compound represented by the following general formula (1). (In general formula (1), R １ ~R ３ Each of these independently represents a fluorine atom, a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group.

6. R in the general formula (1) １ and R ２ Each of these is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, and R ３ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group which may be substituted with a fluorine atom, a halogen atom, or a hydrocarbon group which has a polar group.

7. R in the general formula (1) １ ~ R ３ The non-aqueous electrolyte according to claim 5, wherein each of them is independently a hydrocarbon group which may be substituted with a halogen atom or a hydrocarbon group having a polar group.

8. R in the general formula (1) １ and R ２ Each of these is independently a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group, and R ３ The non-aqueous electrolyte according to claim 5, wherein is a fluorine atom.

9. R in the general formula (1) １ R is a hydrocarbon group which may be substituted with a halogen atom, ３ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group or fluorine atom which may be substituted with a halogen atom.

10. R in the general formula (1) １ R is a hydrocarbon group which may be substituted with a halogen atom, ３ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group which may be substituted with a halogen atom.

11. R in the general formula (1) ２ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group which may be substituted with a halogen atom, or a hydrocarbon group which has a polar group.

12. R in the general formula (1) ２ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group having four or more carbon atoms, which may be substituted with halogen atoms, or a hydrocarbon group having a polar group.

13. R in the general formula (1) ２ The non-aqueous electrolyte according to claim 5, wherein is a hydrocarbon group having a polar group.

14. A method for producing a non-aqueous electrolyte containing an electrolyte, a non-aqueous solvent, and a compound having an Si-F bond, wherein the constituent anion is PF ６ The process includes at least one of the following steps: dissolving an electrolyte containing an anion and a sulfonylimid anion, and a compound having an Si-F bond, in a non-aqueous solvent; and adding a raw material for a compound having an Si-F bond to a solution containing a non-aqueous solvent to generate a compound having an Si-F bond in the solution, wherein the molar concentration [A] of the sulfonylimid anion in the non-aqueous electrolyte and the PF in the non-aqueous electrolyte ６ A method for producing a non-aqueous electrolyte, wherein the total molar concentration [B] of the anion and sulfonylimid anion satisfies the following relationship (I-1): (I-1): 0.05 ≤ [A] / [B] < 1.00 15. A battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte according to any one of claims 1 to 13.

16. A method for manufacturing a battery, comprising the steps of housing a positive electrode and a negative electrode in an outer casing, and injecting a non-aqueous electrolyte according to any one of claims 1 to 13 into the outer casing.

17. A vehicle comprising the battery described in claim 15.

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