Non-aqueous electrolyte and non-aqueous electrolyte battery

Abstract

The present invention is able to provide a nonaqueous electrolyte solution which is capable of exhibiting, in a balanced manner, an effect of improving the capacity retention rate after high-temperature long-term cycles and an effect of suppressing resistance increase at low temperatures after storage at high temperatures and a nonaqueous electrolyte battery which contains this nonaqueous electrolyte solution by means of a nonaqueous electrolyte solution which contains a salt compound represented by a specific general formula, a solute and a nonaqueous organic solvent, wherein the content of the salt compound relative to the total amount of the nonaqueous electrolyte solution is from 0.003% by mass to 0.1% by mass, and a nonaqueous electrolyte battery which contains this nonaqueous electrolyte solution.

Description

[Technical field]

[0001] The present disclosure relates to a nonaqueous electrolyte and a nonaqueous electrolyte battery. [Background technology]

[0002] In recent years, batteries, which are electrochemical devices, have been attracting attention as energy storage systems for small, high-energy density applications such as information-related equipment and communication equipment, i.e., personal computers, video cameras, digital cameras, mobile phones, smartphones, etc., as well as large-scale, power storage systems for power applications such as electric vehicles, hybrid vehicles, and fuel cell vehicle auxiliary power sources, power storage, etc. One candidate is non-aqueous electrolyte batteries, including lithium-ion batteries, which have high energy density and voltage and can provide high capacity, and research and development of these batteries is currently being actively conducted.

[0003] As the nonaqueous electrolyte used in nonaqueous electrolyte batteries, a nonaqueous electrolyte in which a fluorine-containing electrolyte such as lithium hexafluorophosphate (hereinafter LiPF6), lithium bis(fluorosulfonylimide) (hereinafter LiFSI), or lithium tetrafluoroborate (hereinafter LiBF4) is dissolved as a solute in a solvent such as a cyclic carbonate, a chain carbonate, or an ester is often used because it is suitable for obtaining a high-voltage and high-capacity battery. However, nonaqueous electrolyte batteries using such a nonaqueous electrolyte are not necessarily satisfactory in terms of battery characteristics such as cycle characteristics and output characteristics.

[0004] For example, in the case of a lithium-ion secondary battery, when lithium cations are inserted into the negative electrode during the initial charge, the negative electrode and lithium cations, or the negative electrode and the electrolyte solvent, react to form a coating on the surface of the negative electrode, mainly composed of lithium oxide, lithium carbonate, or lithium alkyl carbonate. This coating on the surface of the electrode is called the Solid Electrolyte Interface (SEI), and its properties have a significant effect on battery performance, such as suppressing further reductive decomposition of the solvent and suppressing deterioration of battery performance. Similarly, a coating of decomposition products is also formed on the surface of the positive electrode, which is known to play an important role in suppressing oxidative decomposition of the solvent and suppressing gas generation inside the battery.

[0005] In order to improve battery characteristics such as cycle characteristics and low-temperature characteristics (below 0°C), it is important to form a stable SEI with high ionic conductivity and low electronic conductivity, and there have been many attempts to actively form a good SEI by adding small amounts (usually 0.001% by mass or more and 10% by mass or less) of compounds called additives to the electrolyte.

[0006] For example, Patent Document 1 discloses that an additive with a specific structure that includes a functional group having two different heteroatoms, a phosphorus atom and a sulfur atom, improves the life and storage characteristics of a battery at high temperatures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 103434 Summary of the Invention [Problem to be solved by the invention]

[0008] The electrolyte solution containing the additive of the specific structure described in Patent Document 1 can certainly improve the life characteristics and storage characteristics of a battery at high temperatures. However, the inventors' investigations have revealed that, at the concentration (specifically, about 1% by weight) disclosed in the examples, further improvement is desired in terms of the retention rate of battery capacity after long-term cycles at high temperatures and the increase in resistance at low temperatures after high-temperature storage.

[0009] The present disclosure has been made in consideration of the above circumstances, and aims to provide a nonaqueous electrolyte and a nonaqueous electrolyte battery that can achieve a well-balanced effect of improving the capacity retention rate after long-term cycles at high temperatures (60°C or higher) and suppressing the increase in resistance at low temperatures (0°C or lower, particularly -20°C or lower) after high-temperature storage. [Means for solving the problem]

[0010] In view of such problems, the present inventors have conducted extensive research and found that by using a salt compound represented by general formula (1) as an additive in a non-aqueous electrolyte solution in a content within a specific range relative to the total amount of the non-aqueous electrolyte solution, it is possible to achieve a good balance between the effect of improving the capacity retention rate after long-term cycles at high temperatures and the effect of suppressing an increase in resistance at low temperatures after high-temperature storage.

[0011] That is, the present inventors have found that the above object can be achieved by the following configuration. 〔1〕 A non-aqueous electrolyte solution, The present invention comprises a salt compound represented by the following general formula (1), a solute, and a nonaqueous organic solvent, The content of the salt compound represented by the general formula (1) relative to the total amount of the nonaqueous electrolyte is 0.003% by mass to 0.070% by mass. [ka] [In general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom. X 1 and X 2 each independently represents a halogen atom. M 1+ represents an alkali metal cation, an ammonium ion or an organic cation. n represents an integer of 1 to 6. When n is an integer of 2 or more, a plurality of R 1 may be the same or different, and multiple R 2 may be the same or different.] 〔2〕 The nonaqueous electrolyte solution according to [1], comprising a compound represented by the following general formula (2): [ka] [In general formula (2), R 3 represents a hydrocarbon group having 2 to 5 carbon atoms. The hydrocarbon group may contain a heteroatom between the carbon atom-carbon atom bond. Any hydrogen atom in the hydrocarbon group may be substituted with a halogen atom. 〔3〕 The nonaqueous electrolyte solution according to [1] or [2], comprising a compound represented by the following general formula (3): [ka] [In general formula (3), X 3 and X 4 Each independently represents a halogen atom. M 2 + represents an alkali metal cation, an ammonium ion, or an organic cation. 〔4〕 The non-aqueous electrolyte solution according to any one of [1] to [3], wherein the non-aqueous organic solvent contains at least one selected from the group consisting of cyclic carbonates and chain carbonates. 〔5〕 The nonaqueous electrolyte according to any one of [1] to [4], wherein the solute is an ionic salt consisting of a pair of at least one cation selected from the group consisting of an alkali metal ion and an alkaline earth metal ion and at least one anion selected from the group consisting of a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(pentafluoroethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a (trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoryl)imide anion, a (difluorophosphoryl)(fluorosulfonyl)imide anion, and a (difluorophosphoryl)(trifluoromethanesulfonyl)imide anion. 〔6〕 A non-aqueous electrolyte battery comprising: a positive electrode; a negative electrode having at least one material selected from the group consisting of a negative electrode material containing lithium metal and a negative electrode material capable of absorbing and releasing lithium, sodium, potassium, or magnesium; and the non-aqueous electrolyte according to any one of [1] to [5]. The present invention relates to the above items [1] to [6]. However, other items (e.g., the following items) are also described below. <1> ~ <6> ) is also described.

[0012] <1> A non-aqueous electrolyte solution, The present invention comprises a salt compound represented by the following general formula (1), a solute, and a nonaqueous organic solvent, The content of the salt compound represented by the general formula (1) relative to the total amount of the nonaqueous electrolyte is 0.003% by mass to 0.1% by mass.

[0013] [ka]

[0014] [In general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom. X 1 and X 2 each independently represents a halogen atom. M1 + represents an alkali metal cation, an ammonium ion or an organic cation. n represents an integer of 1 to 6. When n is an integer of 2 or more, a plurality of R 1 may be the same or different, and multiple R 2 may be the same or different.] <2> The compound represented by the following general formula (2) is included: <1> The non-aqueous electrolyte according to claim 1.

[0015] [ka]

[0016] [In general formula (2), R 3 represents a hydrocarbon group having 2 to 5 carbon atoms. The hydrocarbon group may contain a heteroatom between the carbon atom-carbon atom bond. Any hydrogen atom in the hydrocarbon group may be substituted with a halogen atom. <3> The compound represented by the following general formula (3) is included: <1> or <2> The non-aqueous electrolyte according to claim 1.

[0017] [ka]

[0018] [In general formula (3), X 3 and X 4 Each independently represents a halogen atom. M2 + represents an alkali metal cation, an ammonium ion, or an organic cation. <4> The nonaqueous organic solvent contains at least one selected from the group consisting of cyclic carbonates and chain carbonates. <1> ~ <3> 13. The non-aqueous electrolyte solution according to claim 12. <5> The solute is at least one cation selected from the group consisting of alkali metal ions and alkaline earth metal ions, and a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(pentafluoroethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a (trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonyl)imide anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a tri ... R (difluorophosphoric acid)imide anion, R (fluorosulfonyl)imide anion, and (difluorophospho R and at least one anion selected from the group consisting of (trifluoromethanesulfonyl)imide anion and (trifluoromethanesulfonyl)imide anion. <1> ~ <4> 13. The non-aqueous electrolyte solution according to claim 12. <6> a positive electrode, and a negative electrode having at least one material selected from the group consisting of a negative electrode material containing lithium metal and a negative electrode material capable of absorbing and releasing lithium, sodium, potassium, or magnesium; <1> ~ <5> and the nonaqueous electrolyte according to any one of claims 1 to 5. Effect of the Invention

[0019] According to the present disclosure, it is possible to provide a nonaqueous electrolyte and a nonaqueous electrolyte battery that can exhibit a well-balanced effect of improving the capacity retention rate after long-term cycles at high temperatures (60°C or higher) and an effect of suppressing an increase in resistance at low temperatures (0°C or lower, particularly -20°C or lower) after high-temperature storage. [Brief description of the drawings]

[0020] [Figure 1]1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. [Diagram 2] 1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. [Diagram 3] 1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. [Figure 4] 1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. [Diagram 5] 1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. [Figure 6] 1 is a plot of high temperature cycle capacity retention and low temperature internal resistance after high temperature storage versus concentration of component (I) for the Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The configurations and combinations thereof in the following embodiments are examples, and addition, omission, substitution, and other modifications of the configurations are possible without departing from the spirit of the present disclosure. In addition, the present disclosure is not limited to the embodiments. In this specification, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0022] [1. Non-aqueous electrolyte] The nonaqueous electrolyte of the present disclosure is The nonaqueous electrolyte contains a salt compound represented by the following general formula (1), a solute, and a nonaqueous organic solvent, and the content of the salt compound represented by the general formula (1) is 0.003% by mass to 0.1% by mass relative to the total amount of the nonaqueous electrolyte.

[0023] [ka]

[0024] [In general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom. X 1 and X 2 each independently represents a halogen atom. M1 + represents an alkali metal cation, an ammonium ion or an organic cation. n represents an integer of 1 to 6. When n is an integer of 2 or more, a plurality of R 1 may be the same or different, and multiple R 2 may be the same or different.]

[0025] <(I) Salt compound represented by general formula (1)> The salt compound represented by general formula (1) will be described below. The salt compound represented by general formula (1) is also referred to as component (I).

[0026] [ka]

[0027] [In general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom. X 1 and X 2 each independently represents a halogen atom. M1 + represents an alkali metal cation, an ammonium ion or an organic cation. n represents an integer of 1 to 6. When n is an integer of 2 or more, a plurality of R 1 may be the same or different, and multiple R 2 may be the same or different.]

[0028] In general formula (1), R 1 and R 2 each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms.

[0029] R 1 and R 2 When represents an alkyl group having 1 to 6 carbon atoms, examples of the alkyl group include linear or branched alkyl groups, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group. Any hydrogen atom of the alkyl group may be substituted with a fluorine atom. Examples of the alkyl group having any hydrogen atom substituted with a fluorine atom include a trifluoromethyl group, a difluoromethyl group, a fluoromethyl group, a 2,2,2-trifluoroethyl group, a 2,2-difluoroethyl group, and a 2-fluoroethyl group. The alkyl group is preferably a fluorine-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a methyl group, ethyl group, i-propyl group, n-butyl group or trifluoromethyl group, particularly preferably a methyl group.

[0030] R 1 and R 2 are each independently preferably a hydrogen atom, a fluorine atom, or a fluorine-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group; R 1 and R 2 It is particularly preferable that all of are hydrogen atoms.

[0031] In general formula (1), X 1 and X 2 each independently represents a halogen atom. X 1 and X 2 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., and a fluorine atom is preferable. X 1 and X 2may be the same or different, but are preferably the same, and are preferably both fluorine atoms.

[0032] In general formula (1), M1 + are alkali metal cations, ammonium ions (NH4 + ) or an organic cation. M1 + Examples of the alkali metal cation represented by the formula (I) include a lithium cation, a sodium cation, and a potassium cation. M1 + The organic cation represented by is methylammonium ion (MeNH3 + ), dimethylammonium ion (Me2NH2 + ), trimethylammonium ion (Me3NH + ), ethylammonium ion (EtNH3 + ), diethylammonium ion (Et2NH2 + ), triethylammonium ion (EtNH + ), tri-n-propylammonium ion (n-PrNH + ), tri-i-propylammonium ion (i-PrNH + ), n-butylammonium ion (n-BuNH3 + ), tri-n-butylammonium ion (n-Bu3NH + ), sec-butylammonium ion (sec-BuNH3 + ), tert-butylammonium ion (t-BuNH3 + ), diisopropylethylammonium (i-PrEtNH + ), phenylammonium ion (PhNH3 + ), diphenylammonium ion (Ph2NH2 + ), triphenylammonium ion (PhNH + ), tetramethylammonium ion (MeN + ), tetraethylammonium ion (EtN + ), trimethylethylammonium ion (Me3EtN +), tetra-n-propylammonium ion (n-PrN + ), tetra-i-propylammonium ion (i-PrN + ), tetra-n-butylammonium ion (n-Bu4N + ) etc. M1 + is preferably an alkali metal cation, more preferably a lithium cation.

[0033] In the general formula (1), n ​​represents an integer of 1 to 6. n is preferably an integer of 1 to 4, more preferably 2 or 3, and particularly preferably 2.

[0034] Specifically, the anion in the salt compound represented by general formula (1) is preferably at least one selected from the group consisting of the following formulae (1-1) to (1-18), more preferably at least one selected from the group consisting of formulae (1-1), (1-3), (1-5), (1-6), (1-13) and (1-15), and even more preferably at least one selected from the group consisting of formulae (1-1), (1-3) and (1-6).

[0035] [ka]

[0036] The method for synthesizing the salt compound represented by the general formula (1) is not particularly limited, and various known synthesis methods can be used. For example, it can be obtained by reacting a cyclic sulfate with an alkali metal hydroxide to open the ring of the cyclic sulfate, and then further subjecting the resulting product to an addition reaction with phosphorus oxyhalide. Here, X in the salt compound represented by the general formula (1) 1 and X 2When is a fluorine atom, the phosphorus oxyhalide that can be used includes, for example, oxychlorodifluorophosphorus, phosphorus oxyfluoride, phosphorus oxychloride, etc. When phosphorus oxychloride is used, a known fluoride (e.g., HF, NaF, KF, etc.) may be further used to convert the chlorine atoms in the reaction product to fluorine atoms.

[0037] The content of the salt compound represented by the general formula (1) relative to the total amount of the nonaqueous electrolyte solution of the present disclosure is 0.003 mass% (30 ppm by mass) to 0.1 mass% (1000 ppm by mass), preferably 0.0045 mass% (45 ppm by mass) to 0.070 mass% (700 ppm by mass), more preferably 0.006 mass% (60 ppm by mass) to 0.060 mass% (600 ppm by mass), and even more preferably 0.0075 mass% (75 ppm by mass) to 0.055 mass% (550 ppm by mass).

[0038] The salt compound represented by the general formula (1) may be used alone or in combination of two or more kinds.

[0039] <(II) Solute> The nonaqueous electrolyte of the present disclosure includes a solute. The solute is preferably an ionic salt, for example, at least one cation selected from the group consisting of alkali metal ions and alkaline earth metal ions, and a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(pentafluoroethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a (trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoric acid anion, a tetrafluoroborate anion, a trifluoromethanesulfonyl)imide anion, a bis(difluorophosphoric acid anion, a tetrafluoroborate anion, a trifluoromethanesulfonyl)imide anion, a bis(difluorophosphoric acid anion, a tetrafluoroborate anion, a trifluoromethanesulfonyl)(fluoro ... R (difluorophosphoric acid)imide anion, R (fluorosulfonyl)imide anion, and (difluorophospho RIt is preferable that the anion be an ionic salt formed by pairing with at least one anion selected from the group consisting of (trifluoromethanesulfonyl)imide anion and (trifluoromethanesulfonyl)imide anion.

[0040] In addition, the cation of the ionic salt that is the solute is lithium, sodium, potassium, or magnesium, and the anion is a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a bis(difluorophosphoric acid anion, a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonyl)imide ... R (difluorophosphoric acid)imide anion, and R From the viewpoints of high solubility in non-aqueous organic solvents and electrochemical stability, the anion is preferably at least one selected from the group consisting of (fluorosulfonyl)imide anions.

[0041] There is no particular restriction on the suitable concentration of these solutes, but the lower limit is 0.5 mol / L or more, preferably 0.7 mol / L or more, more preferably 0.9 mol / L or more, and the upper limit is 2.5 mol / L or less, preferably 2.2 mol / L or less, more preferably 2.0 mol / L or less. By setting the concentration to 0.5 mol / L or more, it is possible to suppress the deterioration of the cycle characteristics and output characteristics of the nonaqueous electrolyte battery due to the decrease in ion conductivity, and by setting the concentration to 2.5 mol / L or less, it is possible to suppress the deterioration of the cycle characteristics and output characteristics of the nonaqueous electrolyte battery due to the increase in viscosity of the nonaqueous electrolyte. In addition, these solutes may be used alone or in combination.

[0042] In addition, the ionic salts listed as solutes can exert a negative electrode film forming effect and a positive electrode protecting effect as "other additives" when their content in the nonaqueous electrolyte is less than 0.5 mol / L, which is the lower limit of the suitable concentration of the solute.

[0043] <(III) Nonaqueous organic solvents> The type of nonaqueous organic solvent used in the nonaqueous electrolyte solution of the present disclosure is not particularly limited, and any nonaqueous organic solvent can be used. Specifically, ethyl methyl carbonate (hereinafter referred to as "EMC"), dimethyl carbonate (hereinafter referred to as "DMC"), diethyl carbonate (hereinafter referred to as "DEC"), methyl propyl carbonate, ethyl propyl carbonate, methyl butyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, 2,2,2-trifluoroethyl ethyl carbonate, 2,2,2-trifluoroethyl propyl carbonate, bis(2,2,2-trifluoroethyl)carbonate, 1,1,1,3,3,3-hexafluoro-1-propyl methyl carbonate, 1,1,1,3,3,3-hexafluoro-1-propyl ethyl carbonate, 1,1,1,3,3,3-hexafluoro-1-propyl propyl carbonate, bis(1,1,1,3,3,3-hexafluoro-1-propyl)carbonate , ethylene carbonate (hereinafter referred to as "EC"), propylene carbonate (hereinafter referred to as "PC"), butylene carbonate, fluoroethylene carbonate (hereinafter referred to as "FEC"), difluoroethylene carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl 2-fluoropropionate, ethyl 2-fluoropropionate, diethyl ether, dibutyl ether, diisopropyl ether, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, furan, tetrahydropyran, 1,3-dioxane, 1,4-dioxane, N,N-dimethylformamide, acetonitrile, propionitrile, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and γ-valerolactone.

[0044] The nonaqueous organic solvent preferably contains at least one selected from the group consisting of cyclic carbonates and chain carbonates, which provides excellent cycle characteristics at high temperatures, and preferably contains an ester, which provides excellent input / output characteristics at low temperatures. Specific examples of the cyclic carbonate include EC, PC, butylene carbonate, FEC, and the like, and among these, at least one selected from the group consisting of EC, PC, and FEC is preferable. Specific examples of the chain carbonate include EMC, DMC, DEC, methyl propyl carbonate, ethyl propyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, 2,2,2-trifluoroethyl ethyl carbonate, 1,1,1,3,3,3-hexafluoro-1-propyl methyl carbonate, and 1,1,1,3,3,3-hexafluoro-1-propyl ethyl carbonate, and among these, at least one selected from the group consisting of EMC, DMC, DEC, and methyl propyl carbonate is preferred. Specific examples of the ester include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl 2-fluoropropionate, and ethyl 2-fluoropropionate.

[0045] The non-aqueous electrolyte of the present disclosure may contain a polymer, and is generally called a polymer solid electrolyte. Polymer solid electrolytes also include those containing a non-aqueous organic solvent as a plasticizer.

[0046] The polymer is not particularly limited as long as it is an aprotic polymer capable of dissolving the above-mentioned salt compound, the solute, and other additives described below. For example, a polymer having polyethylene oxide in the main chain or side chain, a homopolymer or copolymer of polyvinylidene fluoride, a methacrylic acid ester polymer, polyacrylonitrile, etc. are included. When a plasticizer is added to these polymers, aprotic nonaqueous organic solvents are preferred among the above-mentioned nonaqueous organic solvents.

[0047] <Other additives> As long as the gist of the present disclosure is not impaired, the nonaqueous electrolyte solution of the present disclosure may further contain commonly used additive components in any ratio.

[0048] The nonaqueous electrolyte solution of the present disclosure preferably contains any of the compounds represented by the following general formulas (2) to (6) from the viewpoints of further improving the capacity retention rate after long-term cycles at high temperatures and suppressing an increase in resistance at low temperatures after high-temperature storage, and more preferably contains at least one of the compound represented by general formula (2) and the compound represented by general formula (3).

[0049] [ka]

[0050] [In general formula (2), R 3 represents a hydrocarbon group having 2 to 5 carbon atoms. The hydrocarbon group may contain a heteroatom between the carbon atom-carbon atom bond. Any hydrogen atom in the hydrocarbon group may be substituted with a halogen atom.

[0051] In general formula (2), R 3 R represents a hydrocarbon group having 2 to 5 carbon atoms. 3 Examples of the hydrocarbon group represented by include linear or branched alkylene groups, alkenylene groups, and alkynylene groups. R 3 When represents an alkylene group, specific examples of the alkylene group include an ethylene group, an n-propylene group, an i-propylene group, an n-butylene group, an s-butylene group, a t-butylene group, an n-pentylene group, and a -CH2CH(C3H7)- group. R 3 When represents an alkenylene group, specific examples of the alkenylene group include an ethenylene group and a propenylene group. R 3 When represents an alkynylene group, specific examples of the alkynylene group include an ethynylene group and a propynylene group.

[0052] R 3 The hydrocarbon group represented by may contain a heteroatom between the carbon atom and the carbon atom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0053] R 3 Any hydrogen atom of the hydrocarbon group represented by may be substituted with a halogen atom. Examples of the hydrocarbon group in which any hydrogen atom is substituted with a fluorine atom include a tetrafluoroethylene group, a 1,2-difluoroethylene group, a 2,2-difluoroethylene group, a fluoroethylene group, and a (trifluoromethyl)ethylene group.

[0054] R 3 is preferably an unsubstituted alkylene group having 2 to 3 carbon atoms, and more preferably an ethylene group.

[0055] When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (2), the content of the compound represented by general formula (2) in the nonaqueous electrolyte solution is preferably 0.01 mass % or more and 8.0 mass % or less, based on the total amount of the nonaqueous electrolyte solution. When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (2), it may contain only one type of compound represented by general formula (2), or may contain two or more types of compounds represented by general formula (2).

[0056] [ka]

[0057] [In general formula (3), X 3 and X 4 Each independently represents a halogen atom. M2 + represents an alkali metal cation, an ammonium ion, or an organic cation.

[0058] In general formula (3), X 3 and X 4 represents a halogen atom. 3 and X 4 Examples of the halogen atom represented by include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., and a fluorine atom is preferable. X 3 and X 4 may be the same or different, but are preferably the same, and are preferably both fluorine atoms.

[0059] In general formula (3), M2 + are alkali metal cations, ammonium ions (NH4 + ) or an organic cation. M2 + Examples of the alkali metal cation represented by the formula (I) include a lithium cation, a sodium cation, and a potassium cation. M2 + The organic cation represented by is methylammonium ion (MeNH3 + ), dimethylammonium ion (Me2NH2 + ), trimethylammonium ion (Me3NH + ), ethylammonium ion (EtNH3 + ), diethylammonium ion (Et2NH2 + ), triethylammonium ion (EtNH + ), tri-n-propylammonium ion (n-PrNH + ), tri-i-propylammonium ion (i-PrNH + ), n-butylammonium ion (n-BuNH3 + ), tri-n-butylammonium ion (n-Bu3NH + ), sec-butylammonium ion (sec-BuNH3 + ), tert-butylammonium ion (t-BuNH3 + ), diisopropylethylammonium (i-PrEtNH + ), phenylammonium ion (PhNH3 + ), diphenylammonium ion (Ph2NH2 + ), triphenylammonium ion (PhNH + ), tetramethylammonium ion (MeN + ), tetraethylammonium ion (EtN + ), trimethylethylammonium ion (Me3EtN + ), tetra-n-propylammonium ion (n-PrN + ), tetra-i-propylammonium ion (i-PrN +), tetra-n-butylammonium ion (n-Bu4N + ) etc. M2 + is preferably an alkali metal cation, more preferably a lithium cation.

[0060] When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (3), the content of the compound represented by general formula (3) in the nonaqueous electrolyte solution is preferably 0.01 mass % or more and 8.0 mass % or less, based on the total amount of the nonaqueous electrolyte solution. When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (3), it may contain only one type of compound represented by general formula (3), or may contain two or more types of compounds represented by general formula (3).

[0061] [ka]

[0062] [In general formula (4), R 4 represents a hydrocarbon group having 2 to 6 carbon atoms. The hydrocarbon group may contain a heteroatom between the carbon atom-carbon atom bond. Any hydrogen atom in the hydrocarbon group may be substituted with a halogen atom.

[0063] In general formula (4), R 4 R represents a hydrocarbon group having 2 to 6 carbon atoms. 4 Examples of the hydrocarbon group represented by include linear or branched alkylene groups, alkenylene groups, and alkynylene groups. R 4 When represents an alkylene group, specific examples of the alkylene group include an ethylene group, an n-propylene group, an i-propylene group, an n-butylene group, an s-butylene group, a t-butylene group, an n-pentylene group, a -CHCH(CH)- group, and an n-hexylene group. R 4 When represents an alkenylene group, specific examples of the alkenylene group include an ethenylene group and a propenylene group. R 4When represents an alkynylene group, specific examples of the alkynylene group include a propynylene group.

[0064] R 4 The hydrocarbon group represented by may contain a heteroatom between the carbon atom and the carbon atom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0065] R 4 Any hydrogen atom of the hydrocarbon group represented by may be substituted with a halogen atom. Examples of the hydrocarbon group in which any hydrogen atom is substituted with a fluorine atom include a tetrafluoroethylene group, a 1,2-difluoroethylene group, a 2,2-difluoroethylene group, a fluoroethylene group, and a (trifluoromethyl)ethylene group.

[0066] R 4 is preferably an unsubstituted alkylene group having 3 to 4 carbon atoms, and more preferably a propylene group.

[0067] When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (4), the content of the compound represented by general formula (4) in the nonaqueous electrolyte solution is preferably 0.01 mass % or more and 8.0 mass % or less, based on the total amount of the nonaqueous electrolyte solution. When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (4), it may contain only one type of compound represented by general formula (4), or may contain two or more types of compounds represented by general formula (4).

[0068] [ka]

[0069] [In general formulas (5) and (6), R 5 are each independently a substituent having at least one of an unsaturated bond and an aromatic ring.

[0070] Above R 5is preferably a group selected from an alkenyl group, an alkynyl group, an aryl group, an alkenyloxy group, an alkynyloxy group, and an aryloxy group.

[0071] The alkenyl group is preferably a group selected from ethenyl and 2-propenyl (allyl), the alkynyl group is preferably an ethynyl group, and the aryl group is preferably a phenyl group, a 2-methylphenyl group, a 4-methylphenyl group, a 4-fluorophenyl group, a 4-tert-butylphenyl group, or a 4-tert-amylphenyl group.

[0072] The alkenyloxy group is preferably a group selected from a vinyloxy group and a 2-propenyloxy group (allyloxy group). The alkynyloxy group is preferably a propargyloxy group, and the aryloxy group is preferably a phenoxy group, a 2-methylphenoxy group, a 4-methylphenoxy group, a 4-fluorophenoxy group, a 4-tert-butylphenoxy group, or a 4-tert-amylphenoxy group.

[0073] In addition, the three R 5 From the viewpoint of a high durability improving effect, it is preferable that at least two of the above be ethenyl groups, ethynyl groups, or both.

[0074] When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (5), the content of the compound represented by general formula (5) in the nonaqueous electrolyte solution is preferably 0.01 mass % or more and 8.0 mass % or less, relative to the total amount of the nonaqueous electrolyte solution. When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (5), it may contain only one type of compound represented by general formula (5), or may contain two or more types of compounds represented by general formula (5). When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (6), the content of the compound represented by general formula (6) in the nonaqueous electrolyte solution is preferably 0.01 mass% or more and 8.0 mass% or less, relative to the total amount of the nonaqueous electrolyte solution. When the nonaqueous electrolyte solution of the present disclosure contains a compound represented by general formula (6), it may contain only one type of compound represented by general formula (6), or may contain two or more types of compounds represented by general formula (6).

[0075] Specific examples of "other additives" other than the compounds represented by the above general formulas (2) to (6) include cyclohexylbenzene, cyclohexylfluorobenzene, fluorobenzene (hereinafter, may be referred to as FB), biphenyl, difluoroanisole, tert-butylbenzene, tert-amylbenzene, 2-fluorotoluene, 2-fluorobiphenyl, vinylene carbonate, dimethylvinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, methylpropargyl carbonate, ethylpropargyl carbonate, diphenyl lopargyl carbonate, maleic anhydride, succinic anhydride, methylenemethane disulfonate, dimethylenemethane disulfonate, trimethylenemethane disulfonate, methyl methanesulfonate, lithium difluorobis(oxalato)phosphate (hereinafter sometimes referred to as LDFBOP), sodium difluorobis(oxalato)phosphate, potassium difluorobis(oxalato)phosphate, lithium difluorooxalatoborate (hereinafter sometimes referred to as LDFOB), sodium difluorooxalatoborate, potassium difluorooxalatoborate, Lithium bis(oxalato)borate, Sodium bis(oxalato)borate, Potassium bis(oxalato)borate, Examples of compounds that have an overcharge prevention effect, a negative electrode film forming effect, or a positive electrode protection effect include lithium tetrafluorooxalatophosphate (hereinafter, may be referred to as LTFOP), sodium tetrafluorooxalatophosphate, potassium tetrafluorooxalatophosphate, lithium tris(oxalato)phosphate, sodium tris(oxalato)phosphate, potassium tris(oxalato)phosphate, lithium ethylfluorophosphate (hereinafter, may be referred to as LEFP), lithium propylfluorophosphate, lithium fluorophosphate, ethenesulfonyl fluoride (hereinafter, may be referred to as ESF), trifluoromethanesulfonyl fluoride (hereinafter, may be referred to as TSF), methanesulfonyl fluoride (hereinafter, may be referred to as MSF), and phenyl difluorophosphate (hereinafter, may be referred to as PDFP).

[0076] The content of the other additives in the non-aqueous electrolyte is preferably 0.01 mass % or more and 8.0 mass % or less with respect to the total amount of the non-aqueous electrolyte.

[0077] As the other additives, among those mentioned above, it is preferable to include at least one of the compounds represented by the above general formulas (2) to (6) from the viewpoints of further improving the capacity retention rate after long-term cycles at high temperatures and suppressing an increase in resistance at low temperatures after high-temperature storage, and it is more preferable to include at least one of the compounds represented by general formula (2) and general formula (3).

[0078] In addition, the battery may contain one or more of the following compounds: a lithium salt of a boron complex having an oxalic acid group, a lithium salt of a phosphorus complex having an oxalic acid group, a compound having an O=SF bond, and a compound having an O=PF bond. The battery may contain the above compounds, which is preferable from the viewpoint of not only improving the capacity retention rate after a long-term cycle at a high temperature and suppressing the increase in resistance at a low temperature after high-temperature storage, but also reducing the elution of Ni components from a Ni-containing electrode into the electrolyte when the electrode is used. It is more preferable that the lithium salt of the boron complex having an oxalic acid group is lithium difluorooxalatoborate and the lithium salt of the phosphorus complex having an oxalic acid group is at least one selected from the group consisting of lithium tetrafluorooxalatophosphate and lithium difluorobis(oxalato)phosphate, since this has a particularly excellent effect of suppressing the elution of Ni components from the positive electrode, in addition to further improving the capacity retention rate after long-term cycles at high temperatures and suppressing the increase in resistance at low temperatures after high-temperature storage. Examples of the compound having the O=SF bond include lithium fluorosulfonate, lithium bis(fluorosulfonyl)imide, lithium (trifluoromethanesulfonyl)(fluorosulfonyl)imide, propyl fluorosulfate, phenyl fluorosulfate, 4-fluorophenyl fluorosulfate, 4-tert-butylphenyl fluorosulfate, 4-tert-amylphenyl fluorosulfate, ethenesulfonyl fluoride, trifluoromethanesulfonyl fluoride, methanesulfonyl fluoride, benzenesulfonyl fluoride, 4-fluorophenylsulfonyl fluoride, 4-tert-butylphenylsulfonyl fluoride, 4-tert-amylphenylsulfonyl fluoride, 2-methylphenylsulfonyl fluoride, and the like. Among these, at least one selected from the group consisting of lithium fluorosulfonate, lithium bis(fluorosulfonyl)imide, and (trifluoromethanesulfonyl)(fluorosulfonyl)imide lithium is particularly preferred because it can further improve the capacity retention rate after long-term cycles at high temperatures, suppress the increase in resistance at low temperatures after high-temperature storage, and suppress the elution of Ni components from the positive electrode. Examples of the compound having the O=PF bond include the compound represented by the above general formula (3), such as lithium difluorophosphate, lithium ethyl fluorophosphate, bis(difluorophosphoric acid), R Lithium difluorophosphate, lithium ethyl fluorophosphate, bis(difluorophosphoric acid), lithium phenyl difluorophosphate, and phenyl difluorophosphate are particularly preferred. R At least one selected from the group consisting of lithium fluoride (III) imide and lithium fluoride (III) imide is preferable in that it has a certain degree of effect of improving the capacity retention rate after long-term cycles at high temperatures, suppressing an increase in resistance at low temperatures after high-temperature storage, and suppressing elution of Ni components from the positive electrode, and is particularly highly productive and has low production costs compared to the above-mentioned lithium salt of a boron complex having an oxalic acid group, the lithium salt of a phosphorus complex having an oxalic acid group, and the compound having an O=SF bond. Some of the other additives mentioned above overlap with the solutes, but when used as other additives, they are added at a lower concentration than the solute concentration mentioned above.

[0079] Furthermore, as in the case of a non-aqueous electrolyte battery called a polymer battery, the non-aqueous electrolyte may be quasi-solidified with a gelling agent or a crosslinked polymer.

[0080] <Method of preparing non-aqueous electrolyte> A method for preparing the nonaqueous electrolyte of the present disclosure will now be described. The nonaqueous electrolyte can be prepared by dissolving (II) a solute and (I) a salt compound represented by general formula (1) in (III) a nonaqueous organic solvent. In the operation of dissolving (II) a solute in (III) a nonaqueous organic solvent, it is effective from the viewpoint of preventing deterioration of the nonaqueous organic solvent and the solute to prevent the liquid temperature of the nonaqueous organic solvent from exceeding 40° C. This is because by keeping the liquid temperature at 40° C. or less, it is possible to suppress the generation of free acids such as hydrogen fluoride (HF) caused by the solute reacting with water in the system and decomposing when the solute dissolves, and as a result, it is possible to suppress the decomposition of the nonaqueous organic solvent. In addition, dissolving and blending the solute by adding it little by little is also effective from the viewpoint of suppressing the generation of free acids such as HF. When dissolving a solute in a non-aqueous organic solvent, the non-aqueous organic solvent may be cooled. The liquid temperature is not particularly limited, but is preferably -20 to 40°C, more preferably 0 to 40°C.

[0081] In addition, when the salt compound represented by (I) general formula (1) or other additives are added, the temperature of the nonaqueous electrolyte is preferably controlled to be −10° C. or higher and 40° C. or lower. The upper limit of the temperature is more preferably 30° C. or lower, and particularly preferably 20° C. or lower.

[0082] The nonaqueous electrolyte of the present disclosure can be preferably used in a nonaqueous electrolyte battery (preferably a secondary battery).

[0083] [2. Non-aqueous electrolyte battery] The nonaqueous electrolyte battery of the present disclosure includes at least (a) the nonaqueous electrolyte of the present disclosure, (b) a positive electrode, (c) a negative electrode having at least one material selected from the group consisting of a negative electrode material containing lithium metal and a negative electrode material capable of absorbing and releasing lithium, sodium, potassium, or magnesium, and preferably further includes (d) a separator, an exterior body, and the like.

[0084] <(b) Positive electrode> (b) The positive electrode preferably contains at least one type of oxide and / or polyanion compound as a positive electrode active material.

[0085] [Cathode active material] In the case of a lithium ion secondary battery in which the cations in the nonaqueous electrolyte are mainly lithium, (b) the positive electrode active material constituting the positive electrode is not particularly limited as long as it is a material capable of being charged and discharged. Examples of the positive electrode active material include those containing at least one of (A) lithium transition metal composite oxides containing at least one metal selected from nickel, manganese, and cobalt and having a layered structure, (B) lithium manganese composite oxides having a spinel structure, (C) lithium-containing olivine-type phosphates, and (D) lithium-excess layered transition metal oxides having a layered rock salt structure.

[0086] ((A) Lithium transition metal composite oxide) Examples of the positive electrode active material (A) lithium transition metal composite oxide containing at least one metal selected from nickel, manganese, and cobalt and having a layered structure include lithium-cobalt composite oxide, lithium-nickel composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-cobalt-manganese composite oxide, lithium-nickel-manganese composite oxide, and lithium-nickel-manganese-cobalt composite oxide, etc. In addition, some of the transition metal atoms that are the main components of these lithium transition metal composite oxides may be replaced with other elements such as Al, Ti, V, Cr, Fe, Cu, Zn, Mg, Ga, Zr, Si, B, Ba, Y, and Sn.

[0087] Specific examples of lithium-cobalt composite oxides and lithium-nickel composite oxides include LiCoO2, LiNiO2, and lithium cobalt oxides with added elements such as Mg, Zr, Al, and Ti (LiCo 0.98 Mg 0.01 Zr 0.01 O2, LiCo 0.98 Mg 0.01 Al 0.01 O2, LiCo 0.975 Mg 0.01 Zr 0.005 Al 0.01 LiCoO2, etc., lithium cobalt oxide having a rare earth compound fixed to the surface as described in WO2014 / 034043, etc., may be used. Also, as described in JP2002-151077A, etc., LiCoO2 particles having a part of the particle surface coated with aluminum oxide may be used.

[0088] The lithium-nickel-cobalt composite oxide and the lithium-nickel-cobalt-aluminum composite oxide are represented by the general formula

[11] . Li a Ni 1-b-c Co b M 11 c O2

[11] In formula

[11] , M 11 is at least one element selected from the group consisting of Al, Fe, Mg, Zr, Ti, and B, a satisfies the conditions of 0.9≦a≦1.2, and b and c satisfy the conditions of 0.1≦b≦0.3 and 0≦c≦0.1. These can be prepared, for example, according to the manufacturing method described in JP-A-2009-137834. 0.8 Co 0.2 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.87 Co 0.10 Al 0.03 O2, LiNi 0.6 Co 0.3 Al 0.1 O2, etc.

[0089] Specific examples of lithium-cobalt-manganese composite oxide and lithium-nickel-manganese composite oxide are LiNi 0.5 Mn 0.5 O2, LiCo 0.5 Mn 0.5 O2, etc.

[0090] Lithium-nickel-manganese-cobalt composite oxides include the lithium-containing composite oxides represented by the general formula

[12] . Li d Ni e Mn f Co g M 12 h O2

[12] In formula

[12] , M 12 is at least one element selected from the group consisting of Al, Fe, Mg, Zr, Ti, B, and Sn, d is 0.9≦d≦1.2, and e, f, g, and h satisfy the conditions e+f+g+h=1, 0≦e≦0.7, 0≦f≦0.5, 0≦g≦0.5, and h≧0. The lithium-nickel-manganese-cobalt composite oxide preferably contains manganese in the range shown in the general formula

[12] in order to enhance the structural stability and improve the safety of lithium secondary batteries at high temperatures. It is even more preferable that the lithium-nickel-manganese-cobalt composite oxide further contains cobalt in the range shown in the general formula

[12] in order to enhance the high-rate characteristics of lithium-ion secondary batteries. Specifically, for example, Li[Ni 1 / 3 Mn 1 / 3 Co 1 / 3 ]O2, Li[Ni 0.45 Mn 0.35 Co 0.2 ]O2, Li[Ni 0.5 Mn 0.3 Co 0.2 ]O2, Li[Ni 0.6 Mn 0.2 Co 0.2 ]O2, Li[Ni 0.49 Mn 0.3 Co 0.2 Zr 0.01 ]O2, Li[Ni 0.49 Mn0.3 Co 0.2 Mg 0.01 ]O2, etc.

[0091] ((B) Lithium manganese composite oxide with spinel structure) An example of the positive electrode active material (B) is a lithium manganese composite oxide having a spinel structure, and is, for example, a spinel-type lithium manganese composite oxide represented by the general formula

[13] . Li j (M 2-k M 13 k )O4

[13] In formula

[13] , M 13 is at least one metal element selected from the group consisting of Ni, Co, Fe, Mg, Cr, Cu, Al, and Ti, j is 1.05≦j≦1.15, and k is 0≦k≦0.20. Specifically, for example, LiMnO2, LiMn2O4, LiMn 1.95 Al 0.05 O4, LiMn 1.9 Al 0.1 O4, LiMn 1.9 Ni 0.1 O4, LiMn 1.5 Ni 0.5 Examples include O4.

[0092] ((C) Lithium-containing olivine-type phosphate) An example of the positive electrode active material (C) is a lithium-containing olivine-type phosphate represented by the general formula

[14] . Life 1-n M 14 n PO4

[14] In formula

[14] , M 14 is at least one selected from Co, Ni, Mn, Cu, Zn, Nb, Mg, Al, Ti, W, Zr, and Cd, and n is 0≦n≦1. Specific examples include LiFePO4, LiCoPO4, LiNiPO4, LiMnPO4, and the like, and among these, LiFePO4 and / or LiMnPO4 are preferred.

[0093] ((D) Lithium-excess layered transition metal oxide) As an example of a positive electrode active material, examples of the lithium-excess layered transition metal oxide having a (D) layered rock salt structure include those represented by the general formula

[15] . xLiM 15 O2·(1-x)Li2M 16 O3

[15] In formula

[15] , x is a number satisfying 0 < x < 1, and M 15 is at least one metal element having an average oxidation number of 3 + and M 16 is at least one metal element having an average oxidation number of 4 + . In formula

[15] , M 15 is preferably one metal element selected from trivalent Mn, Ni, Co, Fe, V, and Cr, but the average oxidation number may be made trivalent with an equal amount of divalent and tetravalent metals. Also, in formula

[15] , M 16 is preferably one or more metal elements selected from Mn, Zr, and Ti. Specifically, 0.5[LiNi 0.5 Mn 0.5 O2]·0.5[Li2MnO3], 0.5[LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2]·0.5[Li2MnO3], 0.5[LiNi 0.375 Co 0.25 Mn 0.375 O2]·0.5[Li2MnO3], 0.5[LiNi 0.375 Co 0.125 Fe 0.125 Mn 0.375 O2]·0.5[Li2MnO3], 0.45[LiNi 0.375 Co 0.25 Mn 0.375 O2]·0.10[Li2TiO3]·0.45[Li2MnO3], etc. are included. It is known that the positive electrode active material represented by this general formula

[15] exhibits a high capacity during high-voltage charging of 4.4 V (Li standard) or higher (for example, US Patent 7,135,252). These positive electrode active materials can be prepared in accordance with the manufacturing methods described in, for example, JP-A-2008-270201, WO2013 / 118661, JP-A-2013-030284, and the like.

[0094] The positive electrode active material may contain at least one selected from the above (A) to (D) as a main component, and other components that may be contained include, for example, transition element chalcogenides such as FeS2, TiS2, TiO2, V2O5, MoO3, and MoS2, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, and carbon materials.

[0095] [Positive electrode current collector] (b) The positive electrode has a positive electrode current collector. As the positive electrode current collector, for example, aluminum, stainless steel, nickel, titanium, or an alloy thereof can be used.

[0096] [Cathode active material layer] (b) The positive electrode has, for example, a positive electrode active material layer formed on at least one surface of a positive electrode current collector. The positive electrode active material layer is composed of, for example, the above-mentioned positive electrode active material, a binder, and, if necessary, a conductive agent. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, styrene butadiene rubber (SBR), carboxymethyl cellulose, methyl cellulose, cellulose acetate phthalate, hydroxypropyl methyl cellulose, and polyvinyl alcohol. As the conductive agent, for example, carbon materials such as acetylene black, ketjen black, furnace black, carbon fiber, graphite (granular graphite or flake graphite), fluorinated graphite, etc. are usable. In the positive electrode, it is preferable to use acetylene black or ketjen black, which has low crystallinity.

[0097] <(c) Negative electrode> The negative electrode material is not particularly limited, but in the case of lithium batteries and lithium ion batteries, lithium metal, alloys and intermetallic compounds of lithium metal and other metals, various carbon materials (artificial graphite, natural graphite, etc.), metal oxides, metal nitrides, tin (element), tin compounds, silicon (element), silicon compounds, activated carbon, conductive polymers, etc. may be used.

[0098] Examples of carbon materials include graphitizable carbon, non-graphitizable carbon (hard carbon) with a (002) plane spacing of 0.37 nm or more, and graphite with a (002) plane spacing of 0.34 nm or less. More specifically, there are pyrolytic carbon, cokes, glassy carbon fiber, organic polymer compound sintered bodies, activated carbon, and carbon blacks. Among these, cokes include pitch coke, needle coke, and petroleum coke. Organic polymer compound sintered bodies refer to phenolic resins, furan resins, and the like, which are sintered at an appropriate temperature to be carbonized. Carbon materials are preferable because they undergo very little change in crystal structure due to the absorption and release of lithium, and therefore can provide high energy density and excellent cycle characteristics. The carbon material may be in the form of any of fibers, spheres, particles, and scales. Amorphous carbon and graphite materials coated with amorphous carbon are more preferable because they have a low reactivity between the surface of the material and the nonaqueous electrolyte.

[0099] (c) The negative electrode preferably contains at least one type of negative electrode active material.

[0100] [Negative electrode active material] In the case of a lithium ion secondary battery in which the cations in the non-aqueous electrolyte are mainly lithium, (c) the negative electrode active material constituting the negative electrode is one that can be doped and dedoped with lithium ions, for example, (E) a lattice plane (002 ) surface Carbon material with d value of 0.340 nm or less, (F) lattice plane (002 ) surfaceExamples of the negative electrode active material include a carbon material having a d value of more than 0.340 nm, (G) an oxide of one or more metals selected from Si, Sn, and Al, (H) an alloy containing one or more metals selected from Si, Sn, and Al, or an alloy containing these metals, or an alloy of these metals or alloys with lithium, and (I) a lithium titanium oxide. One of these negative electrode active materials can be used alone, or two or more can be used in combination.

[0101] (E) Lattice plane (002 ) surface Carbon materials with d value of 0.340 nm or less) An example of a negative electrode active material (E) X-ray diffraction lattice plane (002 ) surface Examples of carbon materials having a d value of 0.340 nm or less include pyrolytic carbons, cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), graphites, fired organic polymer compounds (e.g., phenolic resins, furan resins, etc. fired at an appropriate temperature and carbonized), carbon fibers, activated carbons, etc., which may be graphitized. The carbon materials in question are those having a (002) plane spacing (d002) of 0.340 nm or less as measured by X-ray diffraction, and among these, those having a true density of 1.70 g / cm 3 Graphite having the above properties or a highly crystalline carbon material having properties similar thereto is preferred.

[0102] (F) Lattice plane (002 ) surface Carbon materials with d values ​​exceeding 0.340 nm) An example of a negative electrode active material (F) X-ray diffraction lattice plane (002 ) surface Carbon materials with d values ​​exceeding 0.340 nm include amorphous carbon, which is a carbon material in which the stacking order hardly changes even when heat-treated at high temperatures of 2000° C. or higher. Examples include non-graphitizable carbon (hard carbon), mesocarbon microbeads (MCMB) sintered at 1500° C. or lower, and mesope pitch carbon fiber (MCF). Carbotron (registered trademark) P manufactured by Kureha Corporation is a representative example.

[0103] ((G) Oxide of one or more metals selected from Si, Sn, and Al) As an example of the negative electrode active material (G) an oxide of one or more metals selected from Si, Sn and Al, for example, silicon oxide, tin oxide and the like that can be doped / dedoped with lithium ions can be mentioned. SiO2 has a structure in which ultrafine particles of Si are dispersed in SiO2. x When this material is used as the negative electrode active material, charging and discharging are smooth because the Si that reacts with Li is in the form of ultrafine particles, while the SiO x Since the particles themselves have a small surface area, the particles have good paint properties when made into a composition (paste) for forming a negative electrode active material layer, and the negative electrode mixture layer has good adhesion to the current collector. In addition, SiO x Since the volume change during charging and discharging is large, SiO x By using the graphite of the negative electrode active material (E) in a specific ratio in combination with the negative electrode active material, it is possible to achieve both high capacity and good charge / discharge cycle characteristics.

[0104] ((H) One or more metals selected from Si, Sn, and Al, or alloys containing these metals, or alloys of these metals or alloys with lithium) Examples of the negative electrode active material include (H) one or more metals selected from Si, Sn, and Al, or alloys containing these metals, or alloys of these metals or alloys with lithium. Examples of the negative electrode active material include metals such as silicon, tin, and aluminum, silicon alloys, tin alloys, and aluminum alloys. Materials in which these metals and alloys are alloyed with lithium during charge and discharge can also be used. Preferred specific examples of these include metal elements (e.g., powders) such as silicon (Si) and tin (Sn), metal alloys, compounds containing the metals, and alloys containing tin (Sn) and cobalt (Co) in the metals, as described in WO2004 / 100293 and JP2008-016424. When the metals are used in electrodes, they are preferred because they can achieve high charge capacity and the volume expansion and contraction associated with charging and discharging is relatively small. In addition, it is known that when these metals are used in the negative electrode of a lithium ion secondary battery, they are alloyed with Li during charging, resulting in high charge capacity, which is also preferred in this respect. Furthermore, negative electrode active materials formed from silicon pillars with submicron diameters, negative electrode active materials made of silicon fibers, etc., as described in, for example, WO2004 / 042851, WO2007 / 083155, etc., may also be used.

[0105] ((I) Lithium Titanium Oxide) Examples of the negative electrode active material (I) lithium titanium oxide include lithium titanate having a spinel structure and lithium titanate having a ramsdellite structure. Examples of lithium titanate having a spinel structure include Li 4+α Ti5O 12 (α varies within the range of 0≦α≦3 depending on the charge / discharge reaction). Examples of lithium titanate having a ramsdellite structure include Li 2+β Ti3O7 (β varies within the range of 0≦β≦3 depending on the charge / discharge reaction) can be exemplified. These negative electrode active materials can be prepared according to the manufacturing methods described in, for example, JP-A-2007-018883 and JP-A-2009-176752. For example, in the case of a sodium ion secondary battery in which the cations in the non-aqueous electrolyte are mainly sodium, oxides such as hard carbon, TiO2, V2O5, and MoO3 are used as the negative electrode active material. For example, in the case of a sodium ion secondary battery in which the cations in the non-aqueous electrolyte are mainly sodium, sodium-containing transition metal composite oxides such as NaFeO2, NaCrO2, NaNiO2, NaMnO2, and NaCoO2, mixtures of transition metals such as Fe, Cr, Ni, Mn, and Co in these sodium-containing transition metal composite oxides, those in which a part of the transition metal in these sodium-containing transition metal composite oxides is replaced with a metal other than the other transition metal, phosphate compounds of transition metals such as Na2FeP2O7 and NaCo3(PO4)2P2O7, sulfides such as TiS2 and FeS2, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, carbon materials, and the like are used as the positive electrode active material.

[0106] [Negative electrode current collector] (c) The negative electrode has a negative electrode current collector. As the negative electrode current collector, for example, copper, stainless steel, nickel, titanium, or an alloy thereof can be used.

[0107] [Negative electrode active material layer] (c) The negative electrode has, for example, a negative electrode active material layer formed on at least one surface of a negative electrode current collector. The negative electrode active material layer is composed of, for example, the above-mentioned negative electrode active material, a binder, and, if necessary, a conductive agent. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, styrene butadiene rubber (SBR), carboxymethyl cellulose, methyl cellulose, cellulose acetate phthalate, hydroxypropyl methyl cellulose, and polyvinyl alcohol. As the conductive agent, for example, carbon materials such as acetylene black, ketjen black, furnace black, carbon fiber, graphite (granular graphite or flake graphite), and fluorinated graphite can be used.

[0108] <Method of manufacturing electrodes ((b) positive electrode and (c) negative electrode)> The electrode can be obtained, for example, by dispersing and kneading the active material, the binder, and optionally the conductive agent in a predetermined blending amount in a solvent such as N-methyl-2-pyrrolidone (NMP) or water, applying the obtained paste to a current collector, and drying to form an active material layer. The obtained electrode is preferably compressed by a method such as a roll press to adjust the density of the electrode to an appropriate value.

[0109] <(d) Separator> The nonaqueous electrolyte battery may include a separator (d). The separator for preventing contact between the positive electrode (b) and the negative electrode (c) may be a nonwoven fabric or porous sheet made of polyolefin such as polypropylene or polyethylene, cellulose, paper, glass fiber, or the like. These films are preferably microporous so that the nonaqueous electrolyte can penetrate and ions can easily pass through. The polyolefin separator may be, for example, a microporous polymer film such as a porous polyolefin film, which electrically insulates the positive electrode and the negative electrode and allows lithium ions to pass through. Specific examples of the porous polyolefin film include a porous polyethylene film alone, or a multi-layer film formed by stacking a porous polyethylene film and a porous polypropylene film. Also, a composite film of a porous polyethylene film and a polypropylene film may be used.

[0110] <Exterior body> In constructing a nonaqueous electrolyte battery, the exterior body of the nonaqueous electrolyte battery may be, for example, a coin-shaped, cylindrical, or rectangular metal can or a laminate exterior body. Examples of the metal can material include nickel-plated steel plate, stainless steel plate, nickel-plated stainless steel plate, aluminum or its alloy, nickel, titanium, etc. As the laminate exterior body, for example, an aluminum laminate film, a SUS laminate film, a silica-coated polypropylene, a polyethylene laminate film, or the like can be used.

[0111] The configuration of the nonaqueous electrolyte battery according to this embodiment is not particularly limited, but may be, for example, a configuration in which an electrode element in which a positive electrode and a negative electrode are arranged opposite each other and a nonaqueous electrolyte are enclosed in an exterior body. The shape of the nonaqueous electrolyte battery is not particularly limited, but an electrochemical device having a shape such as a coin shape, a cylindrical shape, a square shape, or an aluminum laminate sheet shape is assembled from the above-mentioned elements. EXAMPLES

[0112] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these descriptions in any way.

[0113] [Synthesis of salt compound represented by general formula (1)] [Synthesis Example 1: Synthesis of salt compound (1-1-Li)] In a 500 mL borosilicate glass reactor equipped with a stirrer, 50.1 g (404 mmol, 1 equivalent) of ethylene sulfate (Tokyo Chemical Industry Co., Ltd.) and 101.3 g of ethyl methyl carbonate were added and stirred. After cooling the solution to 5°C, 22.3 g of lithium hydroxide (anhydrous, Tokyo Chemical Industry Co., Ltd., 929 mmol, 2.3 equivalents) was added. The reaction solution was then stirred at 40°C for 12 hours, and the reaction solution was 1 Analysis by H-NMR confirmed that ethylene sulfate was not detected. Next, after cooling this solution to 5°C, 48.6g (404mmol, 1.0 equivalent) of oxychlorodifluorophosphorus was added over 1 hour, and then the mixture was stirred at room temperature (20°C) for 3 hours. The reaction solution obtained was filtered under reduced pressure, and the filtrate was concentrated with an evaporator at a temperature of 50°C under a reduced pressure of 1 to 5kPa to obtain 81.4g (351mmol, 87% yield) of a salt compound (1-1-Li) having an anion represented by the formula (1-1).

[0114] [Synthesis Example 2: Synthesis of salt compound (1-3-Li)] Into a 200 mL borosilicate glass reactor equipped with a stirrer, 10.0 g (72 mmol, 1 equivalent) of 1,3-propylene sulfate (1,3,2-dioxathiane-2,2-dioxide, manufactured by Tokyo Chemical Industry Co., Ltd.) and 30.1 g of ethyl methyl carbonate were added and stirred. After cooling the solution to 5°C, 4.0 g of lithium hydroxide (anhydrous, manufactured by Tokyo Chemical Industry Co., Ltd., 167 mmol, 2.3 equivalents) was added. The reaction solution was then stirred at 40°C for 12 hours, and the reaction solution was 1 Analysis by H-NMR confirmed that 1,3-propylene sulfate was not detected. Next, after cooling this solution to 5°C, 8.7g (72mmol, 1.0 equivalent) of oxychlorodifluorophosphorus was added over 30 minutes, and then the mixture was stirred at room temperature (20°C) for 3 hours. The resulting reaction solution was filtered under reduced pressure, and the filtrate was concentrated with an evaporator at a temperature of 50°C under a reduced pressure of 1 to 5kPa to obtain 14.8g (60mmol, 83% yield) of a salt compound (1-3-Li) having an anion represented by the formula (1-3).

[0115] [Synthesis Example 3: Synthesis of salt compound (1-6-Li)] Into a 200 mL borosilicate glass reactor equipped with a stirrer, 10.2 g (74 mmol, 1 equivalent) of 1,2-propylene sulfate (1,3,2-dioxathiolane-4-methyl-2,2-dioxide, manufactured by Tokyo Chemical Industry Co., Ltd.) and 30.0 g of ethyl methyl carbonate were added and stirred. After cooling the solution to 5°C, 4.1 g of lithium hydroxide (anhydrous, manufactured by Tokyo Chemical Industry Co., Ltd., 170 mmol, 2.3 equivalents) was added. The reaction solution was then stirred at 40°C for 12 hours, and the reaction solution was 1Analysis by H-NMR confirmed that 1,2-propylene sulfate was not detected. Next, after cooling this solution to -10°C, 8.9g (74mmol, 1.0 equivalent) of oxychlorodifluorophosphorus was added over 1 hour, and then the mixture was stirred at 0°C for 3 hours. The reaction solution obtained was filtered under reduced pressure, and the filtrate was concentrated with an evaporator at a temperature of 50°C under a reduced pressure of 1 to 5kPa to obtain 14.3g (58mmol, yield 79%) of a salt compound (1-6-Li) having an anion represented by the formula (1-6).

[0116] The structure of the salt compound represented by formula (1) obtained in the above synthesis example is shown below.

[0117] [ka]

[0118] [Preparation of non-aqueous electrolyte solutions according to examples and comparative examples] <Example 1-1> (Preparation of non-aqueous electrolyte No. 1-1) A mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 2.5:4:3.5 was used as the non-aqueous organic solvent, and LiPF6 was added as a solute to the solvent to a concentration of 1.0 mol / L. The addition was performed with care so that the liquid temperature was in the range of 20 to 30°C. Next, the salt compound (1-1-Li) was dissolved in the non-aqueous electrolyte to a concentration of 0.005 mass % (50 mass ppm) relative to the total amount of the electrolyte. The above preparation was also carried out while maintaining the liquid temperature in the range of 20 to 30°C. The preparation conditions for the non-aqueous electrolyte are shown in Table 1. In all subsequent tables, "-" indicates that no additive was added.

[0119] <Examples 1-2 to 1-5> (Preparation of non-aqueous electrolytes No. 1-2 to 1-5) Non-aqueous electrolyte solutions No. 1-2 to 1-5 were prepared in the same manner as non-aqueous electrolyte solution No. 1-1, except that the concentration of the salt compound (1-1-Li) was changed as shown in Table 1, respectively.

[0120] <Comparative Example 0> (Preparation of Comparative Non-Aqueous Electrolyte No. 0) Comparative nonaqueous electrolyte No. 0 was prepared in the same manner as nonaqueous electrolyte No. 1-1, except that the salt compound (1-1-Li) was not added.

[0121] <Comparative Examples 1-1 to 1-4> (Comparative non-aqueous electrolyte No.1-1~1-4) Comparative nonaqueous electrolyte solutions No. 1-1 to 1-4 were prepared in the same manner as nonaqueous electrolyte solution No. 1-1, except that the concentrations of the salt compounds (1-1-Li) were changed to values ​​outside the range of the present disclosure as shown in Table 1.

[0122] <Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4> (Preparation of non-aqueous electrolytes No. 2-1 to 2-5 and comparative electrolytes No. 2-1 to 2-4) As shown in Table 2, nonaqueous electrolyte solutions No. 2-1 to 2-5 and comparative electrolyte solutions No. 2-1 to 2-4 were prepared in the same manner as nonaqueous electrolyte solutions No. 1-1 to 1-5 and comparative electrolyte solutions No. 1-1 to 1-4, except that the salt compound (1-3-Li) was used instead of the salt compound (1-1-Li).

[0123] <Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-4> (Preparation of non-aqueous electrolytes No. 3-1 to 3-5 and comparative electrolytes No. 3-1 to 3-4) As shown in Table 3, nonaqueous electrolyte solutions No. 3-1 to 3-5 and comparative electrolyte solutions No. 3-1 to 3-4 were prepared in the same manner as nonaqueous electrolyte solutions No. 1-1 to 1-5 and comparative electrolyte solutions No. 1-1 to 1-4, except that the salt compound (1-6-Li) was used instead of the salt compound (1-1-Li).

[0124] <Examples 4-1 to 4-5, Comparative Examples 4-1 to 4-4, Comparative Example 0-1> (Preparation of non-aqueous electrolytes No. 4-1 to 4-5, comparison electrolytes No. 4-1 to 4-4, and comparison electrolyte No. 0-1) Non-aqueous electrolytes Nos. 4-1 to 4-5, 4-1 to 4-4, and 0-1 were prepared in the same manner as non-aqueous electrolytes Nos. 1-1 to 1-5, comparative electrolytes Nos. 1-1 to 1-4, and comparative electrolyte No. 0, except that after dissolving the salt compound (1-1-Li), lithium difluorophosphate (LiPO2F2) was further added as an additive to the concentration shown in Table 4.

[0125] <Examples 5-1 to 5-5, Comparative Examples 5-1 to 5-4, and Comparative Example 0-2> (Preparation of non-aqueous electrolytes No. 5-1 to 5-5, comparison electrolytes No. 5-1 to 5-4, and comparison electrolyte No. 0-2) Non-aqueous electrolytes Nos. 5-1 to 5-5, 5-1 to 5-4, and 0-2 were prepared in the same manner as non-aqueous electrolytes Nos. 1-1 to 1-5, comparative electrolytes Nos. 1-1 to 1-4, and comparative electrolyte No. 0, except that after dissolving the salt compound (1-1-Li), ethylene sulfate (Esa) was further added as an additive to the concentration shown in Table 5.

[0126] <Examples 6-1 to 6-5, Comparative Examples 6-1 to 6-4, and Comparative Example 0-3> (Preparation of non-aqueous electrolytes No. 6-1 to 6-5, comparison electrolytes No. 6-1 to 6-4, and comparison electrolyte No. 0-3) After dissolving the salt compound (1-1-Li), lithium difluorophosphate (LiPO2F2) and ethylene sulfate (Esa) were further added as other additives to the concentrations shown in Table 6, respectively. Non-aqueous electrolytes Nos. 6-1 to 6-5, 6-1 to 6-4, and 0-3 were prepared in the same manner as non-aqueous electrolytes Nos. 1-1 to 1-5, comparative electrolytes Nos. 1-1 to 1-4, and comparative electrolyte No. 0.

[0127] [Preparation of non-aqueous electrolyte battery] Using the above non-aqueous electrolyte, LiNi 0.6 Co 0.2 Mn 0.2 A non-aqueous electrolyte battery (test cell) was fabricated as follows, using O2 as the positive electrode material and graphite as the negative electrode material.

[0128] (Preparation of positive electrode body) LiNi 0.6 Co 0.2 Mn 0.2 90% by mass of O2 powder was mixed with 5% by mass of polyvinylidene fluoride (hereinafter referred to as "PVDF") as a binder and 5% by mass of acetylene black as a conductive material, and N-methylpyrrolidone (hereinafter referred to as "NMP") was added to make a paste. This paste was applied to aluminum foil and dried to make a test cathode body.

[0129] (Preparation of negative electrode body) 90% by mass of graphite powder was mixed with 10% by mass of PVDF as a binder, and NMP was further added to prepare a slurry. This slurry was applied onto copper foil and dried at 120° C. for 12 hours to prepare a test negative electrode body.

[0130] (Preparation of non-aqueous electrolyte battery) A polyethylene separator was impregnated with a non-aqueous electrolyte and a 50 mAh cell with an aluminum laminate exterior was assembled.

[0131] 〔evaluation〕 <Evaluation 1: Capacity retention rate after 500 cycles at 60℃ (high temperature cycle capacity retention rate)> For each of the nonaqueous electrolyte batteries using the nonaqueous electrolytes shown in Tables 1 to 6, the following evaluations were carried out. First, the prepared cell was conditioned under the following conditions at an environmental temperature of 25°C. That is, as the initial charge and discharge, the cell was charged at a constant current and constant voltage of 0.1C rate (5mA) at a charging upper limit voltage of 4.3V, and discharged at a constant current of 0.2C rate (10mA) until the discharge end voltage was 3.0V. The charge and discharge cycle was repeated three times, with the cell being charged at a constant current and constant voltage of 0.2C rate (10mA) at a charging upper limit voltage of 4.3V, and discharged at a constant current of 0.2C rate (10mA) until the discharge end voltage was 3.0V. The capacity obtained at this time was taken as the initial discharge capacity (25°C). After this conditioning, a charge / discharge test was carried out at an ambient temperature of 60° C. The charge was performed by constant-current / constant-voltage charging at a 3C rate (150 mA) up to a maximum charge voltage of 4.3 V, and the discharge was performed by discharging at a constant current of 3C rate (150 mA) up to a discharge cut-off voltage of 3.0 V, repeating this charge / discharge cycle 500 times. The nonaqueous electrolyte battery was then cooled to 25° C. and discharged again to 3.0 V, after which it was charged at a constant current and constant voltage of 25° C. and 0.2 C rate to 4.3 V. Still at 25° C., it was further discharged at a constant current of 0.2 C rate (10 mA) to a discharge cut-off voltage of 3.0 V, and the capacity obtained at this time was recorded as the discharge capacity after 500 cycles at 60° C. Then, the capacity retention rate after 500 cycles at 60° C. was calculated from the initial discharge capacity obtained as described above and the discharge capacity after 500 cycles at 60° C. according to the following formula. Capacity retention rate after 500 cycles at 60℃ [%] = (Discharge capacity after 500 cycles at 60℃) × 100 / Initial discharge capacity

[0132] The results of nonaqueous electrolytes No. 1-1 to 1-5 and comparative nonaqueous electrolytes No. 1-1 to 1-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60°C for Comparative Example 0, which used comparative nonaqueous electrolyte No. 0, was set as 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 7 and FIG. 1.

[0133] The results of nonaqueous electrolytes No. 2-1 to 2-5 and comparative nonaqueous electrolytes No. 2-1 to 2-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60°C for Comparative Example 0, which used comparative nonaqueous electrolyte No. 0, was set as 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 8 and FIG. 2.

[0134] The results of nonaqueous electrolyte Nos. 3-1 to 3-5 and comparative nonaqueous electrolyte Nos. 3-1 to 3-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60° C. was set as 100 for Comparative Example 0 using comparative nonaqueous electrolyte No. 0, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 9 and FIG. 3.

[0135] The results of nonaqueous electrolytes No. 4-1 to 4-5 and comparative nonaqueous electrolytes No. 4-1 to 4-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60°C of Comparative Example 0-1 using comparative nonaqueous electrolyte No. 0-1 was set as a standard, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 10 and FIG. 4.

[0136] The results of nonaqueous electrolyte Nos. 5-1 to 5-5 and comparative nonaqueous electrolyte Nos. 5-1 to 5-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60° C. was set as 100 for Comparative Example 0-2 using comparative nonaqueous electrolyte No. 0-2, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 11 and FIG. 5.

[0137] The results of nonaqueous electrolytes No. 6-1 to 6-5 and comparative nonaqueous electrolytes No. 6-1 to 6-4 were compared. More specifically, the capacity retention rate after 500 cycles at 60°C of Comparative Example 0-3 using comparative nonaqueous electrolyte No. 0-3 was set as a standard, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 12 and FIG. 6. The horizontal axis of the plots in Figures 1 to 6 is on a logarithmic scale. In addition, in FIGS. 1 to 6, the concentration of component (I) on the horizontal axis indicates the concentration of component (I) relative to the total amount of the nonaqueous electrolyte.

[0138] <Evaluation 2: Measurement of the internal resistance of non-aqueous electrolyte batteries after storage at 60°C for 10 days (low-temperature internal resistance after high-temperature storage)> The battery, which had been conditioned in the same manner as in Evaluation 1 above, was charged at a constant current and constant voltage of 0.1C rate (5mA) with a maximum charging voltage of 4.3V, then removed from the charger / discharger maintained at 25°C and stored in a thermostatic chamber at 60°C for 10 days. It was then placed in a charger / discharger maintained at 25°C, discharged at a constant current of 0.2C rate (10mA) to a discharge cut-off voltage of 3.0V, and charged at a constant current and constant voltage of 0.2C rate (10mA) with a maximum charging voltage of 4.3V. Next, the battery was connected to an electrochemical measuring device (Electrofield, automatic battery evaluation device) and placed in a thermostatic chamber at -20° C. After leaving the battery stationary for 1 hour, IV measurements were performed to determine the absolute value of the DC resistance.

[0139] The results of nonaqueous electrolytes No. 1-1 to 1-5 and comparative nonaqueous electrolytes No. 1-1 to 1-4 were compared. More specifically, Comparative Example 0 using comparative nonaqueous electrolyte No. 0 was used as the standard, and the absolute value of the DC resistance was set to 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 7 and FIG. 1.

[0140] The results of nonaqueous electrolytes No. 2-1 to 2-5 and comparative nonaqueous electrolytes No. 2-1 to 2-4 were compared. More specifically, Comparative Example 0 using comparative nonaqueous electrolyte No. 0 was used as the standard, and the absolute value of the DC resistance was set to 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 8 and FIG. 2.

[0141] The results of nonaqueous electrolytes No. 3-1 to 3-5 and comparative nonaqueous electrolytes No. 3-1 to 3-4 were compared. More specifically, Comparative Example 0 using comparative nonaqueous electrolyte No. 0 was used as the standard, and the absolute value of the DC resistance was set to 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 9 and FIG. 3.

[0142] The results of nonaqueous electrolytes No. 4-1 to 4-5 and comparative nonaqueous electrolytes No. 4-1 to 4-4 were compared. More specifically, Comparative Example 0-1 using comparative nonaqueous electrolyte No. 0-1 was used as the standard, and the absolute value of the DC resistance was set to 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 10 and FIG. 4.

[0143] The results of nonaqueous electrolytes No. 5-1 to 5-5 and comparative nonaqueous electrolytes No. 5-1 to 5-4 were compared. More specifically, the absolute value of DC resistance of Comparative Example 0-2 using comparative nonaqueous electrolyte No. 0-2 was set as the standard, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 11 and FIG. 5.

[0144] The results of nonaqueous electrolytes No. 6-1 to 6-5 and comparative nonaqueous electrolytes No. 6-1 to 6-4 were compared. More specifically, Comparative Example 0-3 using comparative nonaqueous electrolyte No. 0-3 was used as the standard, and the absolute value of the DC resistance was set to 100, and the results of the other Examples and Comparative Examples were expressed as relative values. The results are shown in Table 12 and FIG. 6.

[0145] In the following Tables 1 to 6, the concentrations of the salt compound represented by the general formula (1), other additives, or other components are shown relative to the total amount of the nonaqueous electrolyte. In Table 5, Esa represents ethylene sulfate.

[0146] [Table 1]

[0147] [Table 2]

[0148] [Table 3]

[0149] [Table 4]

[0150] [Table 5]

[0151] [Table 6]

[0152] [Table 7]

[0153] [Table 8]

[0154] [Table 9]

[0155] [Table 10]

[0156] [Table 11]

[0157] [Table 12]

[0158] [Table 13]

[0159] From the results in Tables 7 to 12 and Figures 1 to 6, it was confirmed that in the examples in which the content (concentration) of the salt compound (component (I)) represented by general formula (1) is within the range of the present disclosure, the effect of improving the capacity retention rate after high-temperature long-term cycles and the effect of suppressing the increase in internal resistance at low temperatures after high-temperature storage can be exhibited in a well-balanced manner. On the other hand, comparative examples that did not contain the salt compound represented by general formula (1) or in which the content of the salt compound represented by general formula (1) was outside the range of the present disclosure showed inferior results compared to examples that were within the range of the present disclosure.

[0160] In Table 13, Comparative Example 0 is used as the standard, and its capacity retention rate after 500 cycles at 60°C is set as 100, to compare the results of Examples 1-3, 4-3, 5-3, and 6-3 relatively, and Comparative Example 0 is used as the standard, and its low-temperature internal resistance after high-temperature storage is set as 100, to compare the results of Examples 1-3, 4-3, 5-3, and 6-3 relatively. Inclusion of at least one of the compounds represented by general formula (2) and general formula (3) as other additives can further improve the capacity retention rate after long-term cycles at high temperatures (60°C or higher) and further suppress the increase in resistance at low temperatures (0°C or lower, particularly -20°C or lower) after high-temperature storage. This is therefore preferable from the viewpoint of achieving a better balance between the effect of improving the capacity retention rate after long-term cycles at high temperatures and the effect of suppressing the increase in resistance at low temperatures after high-temperature storage. [Industrial Applicability]

[0161] According to the present disclosure, it is possible to provide a nonaqueous electrolyte and a nonaqueous electrolyte battery that can exhibit a well-balanced effect of improving the capacity retention rate after long-term cycles at high temperatures (60°C or higher) and an effect of suppressing an increase in resistance at low temperatures (0°C or lower, particularly -20°C or lower) after high-temperature storage.

[0162] Although the present disclosure 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 disclosure. This application is based on a Japanese patent application (Patent Application No. 2019-105456) filed on June 5, 2019, the contents of which are incorporated herein by reference.

Claims

1. A non-aqueous electrolyte solution, The present invention includes a salt compound represented by the following general formula (1), a solute, and a nonaqueous organic solvent, The content of the salt compound represented by the general formula (1) relative to the total amount of the nonaqueous electrolyte is 0.003% by mass to 0.070% by mass. 【Chemistry 1】 [In general formula (1), R １ and R ２ each independently represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 6 carbon atoms, and any hydrogen atom in the alkyl group may be substituted with a fluorine atom. X １ and X ２ each independently represents a halogen atom. M １ ＋ represents an alkali metal cation, an ammonium ion or an organic cation. n represents an integer of 1 to 6. When n is an integer of 2 or more, a plurality of R １ may be the same or different, and multiple R ２ may be the same or different.

2. The nonaqueous electrolyte according to claim 1 , comprising a compound represented by the following general formula (2): 【Chemistry 2】 [In general formula (2), R ３ represents a hydrocarbon group having 2 to 5 carbon atoms. The hydrocarbon group may contain a heteroatom between a carbon atom-carbon atom bond. Any hydrogen atom in the hydrocarbon group may be substituted with a halogen atom.

3. The nonaqueous electrolyte according to claim 1 or 2, comprising a compound represented by the following general formula (3): 【Chemistry 3】 [In general formula (3), X ３ and X ４ Each independently represents a halogen atom. ２ ＋ represents an alkali metal cation, an ammonium ion, or an organic cation.

4. The non-aqueous electrolyte according to any one of claims 1 to 3, wherein the non-aqueous organic solvent contains at least one selected from the group consisting of cyclic carbonates and chain carbonates.

5. The non-aqueous electrolyte according to any one of claims 1 to 4, wherein the solute is an ionic salt consisting of a pair of at least one cation selected from the group consisting of an alkali metal ion and an alkaline earth metal ion and at least one anion selected from the group consisting of a hexafluorophosphate anion, a tetrafluoroborate anion, a trifluoromethanesulfonate anion, a fluorosulfonate anion, a bis(trifluoromethanesulfonyl)imide anion, a bis(pentafluoroethanesulfonyl)imide anion, a bis(fluorosulfonyl)imide anion, a (trifluoromethanesulfonyl)(fluorosulfonyl)imide anion, a bis(difluorophosphoryl)imide anion, a (difluorophosphoryl)(fluorosulfonyl)imide anion, and a (difluorophosphoryl)(trifluoromethanesulfonyl)imide anion.

6. A non-aqueous electrolyte battery comprising: a positive electrode; a negative electrode having at least one selected from the group consisting of a negative electrode material containing lithium metal, and a negative electrode material capable of absorbing and releasing lithium, sodium, potassium, or magnesium; and the non-aqueous electrolyte according to any one of claims 1 to 5.

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