Nonaqueous electrolyte and energy device using same

Abstract

To provide a non-aqueous electrolytic solution secondary battery that has improved input / output characteristics and has solved problems of the capacity in an endurance test including cycle characteristics and storage characteristics, battery swelling, positive electrode metal elution, and safety.SOLUTION: A non-aqueous electrolytic solution contains one or more compounds selected from a group (A) consisting of a compound represented by X-SO2-Y-SO2-Z (1) [Y is an organic group including one of a nitrogen atom and a carbon atom. X and Z are a hydrocarbon group that may contain a fluorine atom having 1-12 carbon atoms or a fluorine atom. n is an integer of 1 or more and 2 or less.] and a cyclic compound having a SO3 structure, and a fluorosulfonic acid salt (B) represented by (FSO3)xM (2). [M is a metal atom, and x is the valence of the metal atom M and an integer of 1 or more.] The ratio of the content mass of the fluorosulfonic acid salt (B) to the content mass of the compound belonging to the group (A) is 1 or less. The content of the compound belonging to the group (A) is 0.01 mass% or more and 8 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a non-aqueous electrolyte solution and an energy device using the same. [Background technology]

[0002] Energy devices using nonaqueous electrolytes, such as nonaqueous electrolyte secondary batteries, electric double layer capacitors, and lithium ion capacitors, have been put to practical use in a wide range of applications, from so-called consumer power sources for mobile phones, notebook computers, etc. to on-board power sources for driving automobiles, etc., and large-scale stationary power sources, etc. However, in recent years, there has been an increasing demand for higher performance in energy devices, and in particular, nonaqueous electrolyte secondary batteries are required to achieve high levels of various battery characteristics, such as input / output characteristics, durability including cycle characteristics and storage characteristics, and safety. To date, numerous technologies have been investigated for various battery components, including the active materials of the positive and negative electrodes and the nonaqueous electrolyte, as means for improving the input / output characteristics of nonaqueous electrolyte secondary batteries, capacity during durability tests such as cycle characteristics and storage characteristics, battery swelling, positive electrode metal elution, and safety.

[0003] For example, Patent Document 1 discloses a technology for providing a nonaqueous electrolyte battery having excellent output characteristics by containing N(SOF) anions and fluorine-containing inorganic anions, and by setting the mixing ratio of N(SOF) anions to the total amount of anions in the nonaqueous electrolyte to 50 mol % or less.

[0004] Furthermore, Patent Document 2 discloses a technology for providing a nonaqueous electrolyte battery that uses a nonaqueous organic solvent containing propylene carbonate and a nonaqueous electrolyte containing lithium bisfluorosulfonylimide, thereby improving low-temperature output characteristics, high-temperature cycle characteristics, output characteristics after high-temperature storage, capacity characteristics, and battery swelling.

[0005] Furthermore, Patent Document 3 discloses a technology for providing an electrolyte solution for a lithium secondary battery that uses a non-aqueous electrolyte solution containing a cyclic sulfate ester, and that causes less decomposition on the carbon negative electrode as charge-discharge cycles proceed.

[0006] Patent Document 4 also describes a battery containing a layered lithium-nickel composite oxide as a positive electrode active material, and an electrolyte having a methylene disulfone structure (R 1 -SO2-C(R 2 R 3 )2-SO2-R 4 ) compound, thereby obtaining a lithium secondary battery having excellent properties such as excellent energy density and electromotive force, as well as excellent cycle life and storage stability.

[0007] Furthermore, Patent Document 5 discloses a technology in which the use of a nonaqueous electrolyte containing an unsaturated sultone suppresses the decomposition reaction of the solvent on the negative electrode, thereby suppressing the decrease in battery capacity, gas generation, and deterioration of the battery's load characteristics during high-temperature storage.

[0008] Furthermore, Patent Document 6 discloses a technology for providing a nonaqueous electrolyte secondary battery that uses a nonaqueous electrolyte containing LiPF6 and a fluorosulfonate, and that improves the initial charge capacity, input / output characteristics, and impedance characteristics by setting the molar content of FSO3 relative to the molar content of PF6 to 0.001 to 1.2, thereby maintaining not only initial battery characteristics and durability but also high input / output characteristics and impedance characteristics even after endurance. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-129797 [Patent Document 2] Special Publication No. 2015-509271 [Patent Document 3] Japanese Patent Application Publication No. 10-189042 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-156314 [Patent Document 5] Japanese Patent Application Laid-Open No. 2002-329528 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-187440 Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, in recent years, there has been an increasing demand for higher performance nonaqueous electrolyte secondary batteries, and there is a demand for further improvements in the performance of nonaqueous electrolyte secondary batteries, that is, improvements in input / output characteristics, capacity during durability tests such as cycle characteristics and storage characteristics, battery swelling, positive electrode metal elution, and safety. However, it is difficult to say that the compounds described in Patent Documents 1 to 6 and nonaqueous electrolyte batteries using electrolytes containing them have yet to sufficiently improve the above-mentioned problems.

[0011] The reason for this has not yet been fully elucidated, but is speculated as follows. That is, in order to improve the charge transfer reaction rate of lithium ions, it is necessary to suppress side reactions such as solvent decomposition on the electrode surface and promote the permeation of lithium ions. However, the techniques described in Patent Documents 1 to 6 alone do not adequately balance these two factors, and as a result, it has not been possible to maximize both input / output characteristics and durability. In particular, in recent batteries where the amount of electrolyte injected has been reduced in an effort to achieve higher energy density, if there is a small amount of additives that reduce the reactivity of the electrode surface, side reactions are more likely to occur, resulting in a significant decline in input / output characteristics.

[0012] The present invention has been made in view of the above background art, and an object of the present invention is to provide a non-aqueous electrolyte solution that is excellent in input / output characteristics and durability. [Means for solving the problem]

[0013] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that input / output characteristics can be significantly improved by adding one or more compounds selected from the group consisting of compounds represented by X-SO2-Y-SO2-Z and cyclic compounds having an SO3 structure, and a fluorosulfonate salt having a specific structure to a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent for dissolving the electrolyte, and by controlling the content of the compound selected from the group consisting of compounds represented by X-SO2-Y-SO2-Z and cyclic compounds having an SO3 structure in the non-aqueous electrolyte solution to be within a specific range and controlling the ratio of the mass content of the specific fluorosulfonate salt to the content to be 1 or less, thereby completing the present invention.

[0014] More specifically, in order to develop a novel non-aqueous electrolyte that significantly improves input / output characteristics and durability over conventional ones, the inventors focused on the film formation mechanism and elementary reaction rates on the surfaces of the positive and negative electrodes of non-aqueous electrolyte secondary batteries as energy devices, and conducted extensive studies on the effects of various compounds and their combinations.

[0015] The electrode reaction rate, which is related to the input / output characteristics of non-aqueous electrolyte batteries, is determined by various factors such as the oxidation-reduction stability of the compound itself, the concentration and viscosity (diffusion coefficient) of the compound on the electrode surface, and the stability of the product after the reaction. The technology described in Patent Documents 1 and 2 controls the charge transfer reaction on the electrode surface by directly introducing (FSO2)2NLi into the electrolyte. The specific compounds described in Patent Documents 3 to 5 are not electrolyte salts, but are decomposed by electrochemical reduction or the like in the battery to form sulfonates. These compounds produce sulfuric acid salts, sulfates, etc. Although these compounds are effective in promoting the supply of lithium ions to the battery surface, they are insufficient in terms of, for example, deactivating the reactive sites on the electrode surface, resulting in drawbacks such as increased initial resistance and resistance after endurance. The present inventors discovered that by introducing a specific fluorosulfonate, which has the property of increasing the lithium ion concentration on the positive and negative electrode surfaces and deactivating the reactive sites on the positive and negative electrode surfaces to efficiently protect the positive and negative electrode surfaces, together with a compound selected from the group consisting of compounds represented by X-SO2-Y-SO2-Z and cyclic compounds having an SO3 structure, and by controlling the contents of both, the balance between lithium ion supply and electrode reactivity is achieved, thereby maximizing the effects of improving input / output characteristics and durability, and thus completing the present invention.

[0016] That is, the present invention provides specific embodiments shown in [1] to [9] below. [1] The following formula (1): X-SO2-Y-SO2-Z (1) [In formula (1), Y is an organic group containing either a nitrogen atom or a carbon atom. In the case of a nitrogen atom, Y is an imide-structured lithium salt of N-Li. In the case of a carbon atom, Y is an imide-structured lithium salt of -O-(CH2) n It is an alkylene diester structure of -O-. X and Z are fluorine atoms or hydrocarbon groups having 1 to 12 carbon atoms which may contain a fluorine atom. X and Z may be the same or different, and may be bonded to each other to form a ring structure. When a ring structure is formed, either X or Z may be removed. n is an integer of 1 or more and 2 or less.] and one or more compounds selected from group (A) consisting of compounds represented by the formula (I) and cyclic compounds having an SO structure, The following formula (2): (FSO3) x M (2) [In formula (2), M is a metal atom, and x is the valence of the metal atom M and is an integer of 1 or more] A non-aqueous electrolyte solution containing a fluorosulfonate (B) represented by a ratio of the mass content of the fluorosulfonate (B) to the mass content of the compound belonging to group (A) in the nonaqueous electrolyte solution being 1 or less, and the content of the compound belonging to group (A) in the nonaqueous electrolyte solution being 0.01 mass % or more and 8 mass % or less. [2] The non-aqueous electrolyte solution according to [1], wherein the content of the fluorosulfonate (B) in the non-aqueous electrolyte solution is 2 mass % or less. [3] The nonaqueous electrolyte solution according to [1] or [2], wherein the fluorosulfonate (B) contains FSO3Li. [4] The nonaqueous electrolyte solution according to any one of [1] to [3], wherein the compound represented by formula (1) is (FSO2)2NLi, (CF3SO2)2NLi, or (C2F5SO2)2NLi. [5] The nonaqueous electrolyte solution according to any one of [1] to [4], wherein the cyclic compound having an SO3 structure is 1,3-propane sultone, 1,3-propene sultone, or 1,2-ethylene sulfate. [6] The non-aqueous electrolyte solution according to any one of [1] to [5], wherein the non-aqueous electrolyte solution contains LiPF6. [7] An energy device comprising a plurality of electrodes capable of absorbing and releasing metal ions and the nonaqueous electrolyte solution according to any one of [1] to [6]. [8] The energy device according to [7], wherein the plurality of electrodes capable of absorbing and releasing metal ions are a positive electrode and a negative electrode, and the negative electrode contains a carbonaceous material or a material containing silicon. [9] The energy device according to [7] or [8], wherein the plurality of electrodes capable of absorbing and releasing metal ions are a positive electrode and a negative electrode, and the positive electrode contains a transition metal oxide. [Effects of the Invention]

[0017] According to the present invention, the initial input / output characteristics are significantly improved, and furthermore, the characteristics are excellent during cycle operation and high-temperature storage. This provides a nonaqueous electrolyte solution capable of realizing an energy device such as a nonaqueous electrolyte secondary battery that is excellent in input / output retention rate, capacity retention rate, battery swelling, and metal elution during charging / discharging. Furthermore, according to a preferred embodiment of the present invention, it is possible to provide a nonaqueous electrolyte solution capable of realizing an energy device that is excellent not only in input / output characteristics but also in impedance characteristics, charge / discharge rate characteristics, etc., and further in continuous charging characteristics, safety, etc. Furthermore, it is possible to provide an energy device using this nonaqueous electrolyte solution. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail. The following embodiments are examples (typical examples) of the present invention, and the present invention is not limited to these. Furthermore, the present invention can be implemented with any modifications within the scope of the gist thereof.

[0019] <1. Compounds Essential for the Non-Aqueous Electrolyte Solution of the Present Invention> The nonaqueous electrolyte solution of the present invention comprises a compound represented by the following formula (1): X-SO2-Y-SO2-Z (1) [In formula (1), Y is an organic group containing either a nitrogen atom or a carbon atom. In the case of a nitrogen atom, Y is an imide-structured lithium salt of N-Li. In the case of a carbon atom, Y is an imide-structured lithium salt of -O-(CH2) n It is an alkylene diester structure of -O-. X and Z are fluorine atoms or hydrocarbon groups having 1 to 12 carbon atoms which may contain a fluorine atom. X and Z may be the same or different, and may be bonded to each other to form a ring structure. When a ring structure is formed, either X or Z may be removed. n is an integer of 1 or more and 2 or less.] and a cyclic compound having an SO structure, and the compound is represented by the following formula (2): (FSO3) x M (2) [In formula (2), M is a metal atom, and x is the valence of the metal atom M and is an integer of 1 or more] The compound contains a fluorosulfonic acid salt (B) represented by the formula:

[0020] <1-1. Compounds selected from group (A) consisting of compounds represented by X-SO2-Y-SO2-Z and cyclic compounds having an SO3 structure> <1-1-1. Compounds represented by X-SO2-Y-SO2-Z> In formula (1), Y is an organic group containing either a nitrogen atom or a carbon atom. If Y is a nitrogen atom, it is an imide-structured lithium salt called N-Li. If Y is a carbon atom, it is -O-(CH2) n It is an alkylene diester structure of -O-. X and Z are fluorine atoms or hydrocarbon groups having 1 to 12 carbon atoms which may contain a fluorine atom. X and Z may be the same or different, and may be bonded to each other to form a ring structure. When a ring structure is formed, either X or Z may be removed. n is an integer of 1 or more and 2 or less.

[0021] When Y is a nitrogen atom, the lithium salt has an imide structure, and X and Z are preferably a hydrocarbon group containing a fluorine atom having 1 to 4 carbon atoms or a fluorine atom, from the viewpoint of increasing the lithium ion concentration and improving the conductivity derived from the lithium ions.

[0022] Preferred lithium salts of imide structure include (FSO2)2NLi, (FSO2)(CF3SO2)NLi, (CF3SO2)2NLi, (C2F5SO2)2NLi, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, (CF3SO2)(C4F9SO2)NLi, and the like.

[0023] Among these, (FSO2)2NLi, (CF3SO2)2NLi, and (C2F5SO2)2NLi are more preferable from the viewpoint of not reducing the viscosity of the electrolyte, and (FSO2)2NLi is more preferable from the viewpoint of improving the input / output characteristics and durability.

[0024] Furthermore, when Y is a carbon atom, the compound has an alkylene diester structure, and X and Z are hydrocarbon groups having 1 to 6 carbon atoms, which is preferable from the viewpoint of not reducing the viscosity of the electrolyte.

[0025] Preferred compounds having an alkylene disulfonate structure include: cyclic disulfonic acid ester compounds such as methylenemethane disulfonate, ethylenemethane disulfonate, methyleneethane disulfonate, and ethyleneethane disulfonate; Chain disulfonic acid ester compounds such as methylene bis(methanesulfonate), methylene bis(ethanesulfonate), methylene bis(benzenesulfonate), ethylene bis(methanesulfonate), ethylene bis(ethanesulfonate), and ethylene bis(benzenesulfonate); etc.

[0026] Among these, methylenemethane disulfonate, ethylene methane disulfonate, and methylene bis(methanesulfonate) are preferred from the viewpoint of improving input / output characteristics, and methylene methane disulfonate is more preferred from the viewpoint of improving input / output characteristics and durability.

[0027] The content of the compound represented by X-SO2-Y-SO2-Z in the nonaqueous electrolyte solution of the present invention is 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and 8% by mass or less, preferably 7% by mass or less, more preferably 6% by mass or less. A content within the above range is preferable because it can further improve not only input / output characteristics but also durability such as cycle capacity and storage capacity, further reduce battery swelling and metal elution, and improve safety.

[0028] <1-1-2. Cyclic compounds containing SO3 groups> The cyclic compound having an SO3 group that can be used in the nonaqueous electrolyte solution of the present invention is not particularly limited as long as it is a cyclic compound having an SO3 group in the molecule, but is preferably a compound having a cyclic sulfonate ester or a cyclic sulfate ester (hereinafter sometimes abbreviated as a cyclic sulfonate ester compound or a cyclic sulfate ester compound, respectively), and more preferably a compound represented by the following general formula (3): The method for producing the cyclic compound having an SO3 group is not particularly limited, and it can be produced by any known method.

[0029] [ka]

[0030] In general formula (3), R 7 and R 8 each independently represents an organic group composed of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, and halogen atoms; R 7 and R 8 may contain an unsaturated bond together with -SO3-. where R 7 and R 8 is preferably an organic group composed of atoms consisting of carbon atoms, hydrogen atoms, oxygen atoms, and sulfur atoms, and is particularly preferably an organic group having a hydrocarbon group of 1 to 3 carbon atoms, -SO3-.

[0031] The molecular weight of the cyclic compound having an SO3 group is not particularly limited, and it is not particularly limited as long as it does not significantly impair the effects of the present invention. The molecular weight of the cyclic compound having an SO group is usually 100 or more, preferably 110 or more, and usually 250 or less, preferably 220 or less. Within this range, the solubility of the cyclic compound having an SO group in the non-aqueous electrolyte solution is easily ensured, and the effects of the present invention are easily achieved.

[0032] Specific examples of the compound represented by general formula (3) include: 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-fluoro-2-propene-1,3- Sultone, 2-fluoro-2-propene-1,3-sultone, 3-fluoro-2-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-propene-1,3-sultone, 3-methyl-1-propene-1,3-sultone, 1-methyl-2-propene-1,3-sultone, 2-methyl-2-propene-1,3-sultone, 3-methyl-2-propene-1,3-sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1,4-butane sultone, 3-fluoro-1,4-butane sultone sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1,4-butane sultone, 4-methyl-1,4-butane sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1-fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1,4-sultone, 1-fluoro-2-butene-1,4-sultone, 2- Fluoro-2-butene-1,4-sultone, 3-fluoro-2-butene-1,4-sultone, 4-fluoro-2-butene-1,4-sultone, 1-fluoro-3-butene-1,4-sultone, 2-fluoro-3-butene-1,4-sultone, 3-fluoro-3-butene-1,4-sultone, 4-fluoro-3-butene-1,4-sultone, 1-methyl-1-butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4-sultone, 1-methyl-2-butene-1,4-sultone, 2-methyl-2-butene-1,4-sultone, 3-methyl-2-butene-1,4-sultone, 4-methyl-2-butene-1,4-sultone, 1-methyl-3-butene-1,4-sultone, 2-methyl-3-butene-1,4-sultone, 3-methyl-3-butene-1,4-sultone, 4-methyl-3-butene-1,4-sultone, 1,5-pentane sultone, 1-fluoro-1,5-pentane sultone, 2-fluoro Fluoro-1,5-pentane sultone, 3-fluoro-1,5-pentane sultone, 4-fluoro-1,5-pentane sultone, 5-fluoro-1,5-pentane sultone, 1-methyl-1,5-pentane sultone, 2-methyl-1,5-pentane sultone, 3-methyl-1,5-pentane sultone, 4-methyl-1,5-pentane sultone, 5-methyl-1,5-pentane sultone, 1-pentene-1,5-sultone, 2-pentene-1,5-sultone pentene-1,5-sultone, 3-pentene-1,5-sultone, 4-pentene-1,5-sultone, 1-fluoro-1-pentene-1,5-sultone, 2-fluoro-1-pentene-1,5-sultone, 3-fluoro-1-pentene-1,5-sultone, 4-fluoro-1-pentene-1,5-sultone, 5-fluoro-1-pentene-1,5-sultone, 1-fluoro-2-pentene-1,5-sultone, 2-fluoro- 2-pentene-1,5-sultone, 3-fluoro-2-pentene-1,5-sultone, 4-fluoro-2-pentene-1,5-sultone, 5-fluoro-2-pentene-1,5-sultone, 1-fluoro-3-pentene-1,5-sultone, 2-fluoro-3-pentene-1,5-sultone, 3-fluoro-3-pentene-1,5-sultone, 4-fluoro-3-pentene-1,5-sultone, 5-fluoro-3-pentene, -1,5-sultone, 1-fluoro-4-pentene-1,5-sultone, 2-fluoro-4-pentene-1,5-sultone, 3-fluoro-4-pentene-1,5-sultone, 4-fluoro-4-pentene-1,5-sultone, 5-fluoro-4-pentene-1,5-sultone, 1-methyl-1-pentene-1,5-sultone, 2-methyl-1-pentene-1,5-sultone, 3-methyl-1-pentene-1 ,5-sultone, 4-methyl-1-pentene-1,5-sultone, 5-methyl-1-pentene-1,5-sultone, 1-methyl-2-pentene-1,5-sultone, 2-methyl-2-pentene-1,5-sultone, 3-methyl-2-pentene-1,5-sultone, 4-methyl-2-pentene-1,5-sultone, 5-methyl-2-pentene-1,5-sultone, 1-methyl-3-pentene-1,5-sultone , 2-methyl-3-pentene-1,5-sultone, 3-methyl-3-pentene-1,5-sultone, 4-methyl-3-pentene-1,5-sultone, 5-methyl-3-pentene-1,5-sultone, 1-methyl-4-pentene-1,5-sultone, 2-methyl-4-pentene-1,5-sultone, 3-methyl-4-pentene-1,5-sultone, 4-methyl-4-pentene-1,5-sultone, 5-methyl- Sultone compounds such as 4-pentene-1,5-sultone, 1,2-oxathiolan-2,2-dioxid-4-yl-acetate, 1,2-oxathiolan-2,2-dioxid-4-yl-propionate, 5-methyl-1,2-oxathiolan-2,2-dioxid-4-one-2,2-dioxide, and 5,5-dimethyl-1,2-oxathiolan-2,2-dioxid-4-one-2,2-dioxide;

[0033] 1,2,3-Oxathiazolidine-2,2-dioxide, 3-methyl-1,2,3-oxathiazolidine-2,2-dioxide, 3H-1,2,3-oxathiazole-2,2-dioxide, 5H-1,2,3-oxathiazole-2,2-dioxide, 1,2,4-oxathiazolidine-2,2-dioxide, 4-methyl-1,2,4-oxathiazolidine-2,2-dioxide, 3H-1,2,4-oxathiazole-2,2-dioxide, 5H-1,2,4-oxathiazole-2,2-dioxide 1,2,5-oxathiazolidine-2,2-dioxide, 5-methyl-1,2,5-oxathiazolidine-2,2-dioxide, 3H-1,2,5-oxathiazole-2,2-dioxide, 5H-1,2,5-oxathiazole-2,2-dioxide, 1,2,3-oxathiazinane-2,2-dioxide, 3-methyl-1,2,3-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,3-oxathiazine-2,2-dioxide, 1,2,4-oxathiazinane-2,2-dioxide oxide, 4-methyl-1,2,4-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,4-oxathiazine-2,2-dioxide, 3,6-dihydro-1,2,4-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,4-oxathiazine-2,2-dioxide, 1,2,5-oxathiazinane-2,2-dioxide, 5-methyl-1,2,5-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,6 -Nitrogen-containing compounds such as dihydro-1,2,5-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,5-oxathiazine-2,2-dioxide, 1,2,6-oxathiazinane-2,2-dioxide, 6-methyl-1,2,6-oxathiazinane-2,2-dioxide, 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide, 3,4-dihydro-1,2,6-oxathiazine-2,2-dioxide, and 5,6-dihydro-1,2,6-oxathiazine-2,2-dioxide; 1,2,3-Oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiafoslan-2,2-dioxide, 3-methyl-1,2,3-oxathiafoslan-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiafoslan-2,2,3-trioxide, 1,2,4-oxathiafoslan-2,2-dioxide, 4-methyl-1,2,4-oxathiafoslan-2,2,4-trioxide, 4-methoxy-1,2,4-oxathiafoslan-2,2,4-trioxide, 1,2,5-oxathiafoslan-2,2-dioxide oxide, 5-methyl-1,2,5-oxathiafoslan-2,2-dioxide, 5-methyl-1,2,5-oxathiafoslan-2,2,5-trioxide, 5-methoxy-1,2,5-oxathiafoslan-2,2,5-trioxide, 1,2,3-oxathiafosphinane-2,2-dioxide, 3-methyl-1,2,3-oxathiafosphinane-2,2-dioxide, 3-methyl-1,2,3-oxathiafosphinane Thiaphosphinane-2,2,3-trioxide, 3-methoxy-1,2,3-oxathiaphosphinane-2,2,3-trioxide, 1,2,4-oxathiaphosphinane-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinane-2,2-dioxide, 4-methyl-1,2,4-oxathiaphosphinane-2,2,3-trioxide, 4-methyl-1,5,2,4-dioxathiaphosphinane -2,4-dioxide, 4-methoxy-1,5,2,4-dioxathiaphosphinane-2,4-dioxide, 3-methoxy-1,2,4-oxathiaphosphinane-2,2,3-trioxide, 1,2,5-oxathiaphosphinane-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinane-2,2-dioxide, 5-methyl-1,2,5-oxathiaphosphinane-2,2,3-trioxide phosphorus-containing compounds such as 5-methoxy-1,2,5-oxathiaphosphinane-2,2,3-trioxide, 1,2,6-oxathiaphosphinane-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinane-2,2-dioxide, 6-methyl-1,2,6-oxathiaphosphinane-2,2,3-trioxide, and 6-methoxy-1,2,6-oxathiaphosphinane-2,2,3-trioxide; alkylene sulfate compounds such as 1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate, 1,3-butylene sulfate, 1,4-butylene sulfate, 1,2-pentylene sulfate, 1,3-pentylene sulfate, 1,4-pentylene sulfate, and 1,5-pentylene sulfate, vinylene sulfate; etc.

[0034] Among these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2-fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1,4-butane sultone, methylenemethane disulfonate, ethylenemethane disulfonate, 1,2-ethylene From the viewpoint of improving storage properties, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone, methylenemethane disulfonate, ethylenemethane disulfonate, 1,2-ethylene sulfate, and 1,3-propylene sulfate are preferred, and 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-propene-1,3-sultone, methylenemethane disulfonate, ethylenemethane disulfonate, 1,2-ethylene sulfate, and 1,3-propylene sulfate are more preferred.

[0035] The cyclic compound having an SO group may be used alone or in any combination and ratio of two or more. The content of the cyclic compound having an SO group relative to the entire non-aqueous electrolyte solution of the present invention is 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, and 8% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the above range is satisfied, it is preferable from the viewpoint of improving cycle characteristics, high-temperature storage characteristics, etc., and reducing battery swelling.

[0036] The non-aqueous electrolyte solution of the present invention may contain a plurality of compounds belonging to group (A). In this case, the total content of the compounds belonging to group (A) relative to the non-aqueous electrolyte solution of the present invention is 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and 8% by mass or less, preferably 7% by mass or less, more preferably 6% by mass or less. is. The method for producing the compound selected from the group consisting of the compound represented by X-SO2-Y-SO2-Z and the cyclic compound having an SO3 structure is not particularly limited, and the compound can be produced by combining known methods.

[0037] <1-2.(FSO3) x M> The nonaqueous electrolyte of the present invention is a compound represented by the formula (2): (FSO3) x The fluorosulfonate (B) is represented by M. In formula (2), M is a metal atom, and x is the valence of the metal atom M and is an integer of 1 or more. The fluorosulfonate (B) may be used alone or in combination of two or more.

[0038] In formula (2), x is the valence of the metal atom and is an integer of 1 or more, specifically 1, 2, or 3. Examples of the metal atom include alkali metals such as lithium, sodium, potassium, and cesium, alkaline earth metals such as magnesium and calcium, and transition metals such as iron and copper, with lithium being particularly preferred.

[0039] Preferable fluorosulfonates (B) include FSO3Li, FSO3Na, FSO3K, FSO3Cs, (FSO3)2Mg, (FSO3)2Ca, (FSO3)2Fe, (FSO3)2Cu, (FSO3)3Al, etc. Among these, FSO3Li, FSO3Na, and FSO3K are particularly preferable, and FSO3Li is most preferable from the viewpoint of being able to improve the lithium ion concentration in the battery. The method for synthesizing and obtaining the fluorosulfonate (B) is not particularly limited, and any method for synthesis or acquisition can be used. Examples of methods for synthesizing the metal salt of fluorosulfonic acid (B) include a method of reacting a metal fluoride or a metal fluoride silicon compound with SO to obtain a metal salt of fluorosulfonic acid, a method of reacting fluorosulfonic acid with a metal and obtaining a metal salt of fluorosulfonic acid by ion exchange, a method of reacting an ammonium salt of fluorosulfonic acid with a metal to obtain a metal salt of fluorosulfonic acid, a method of reacting fluorosulfonic acid with a metal salt of acetic acid and obtaining a metal salt of fluorosulfonic acid by ion exchange, and a method of reacting fluorosulfonic acid with a metal halide to obtain a metal salt of fluorosulfonic acid.

[0040] The nonaqueous electrolyte solution of the present invention may contain one or more fluorosulfonates (B), and one may be used alone or two or more may be used in combination. When two or more are used, it is preferable that one of them is FSO3Li. In particular, a combination of FSO3Li with one or more selected from FSO3Na and FSO3K is preferable. Specifically, the combinations of FSO3Li and FSO3Na, and FSO3Li and FSO3K are preferred in terms of increasing the lithium concentration in the non-aqueous electrolyte solution.

[0041] The content of fluorosulfonate (B) in the nonaqueous electrolyte solution of the present invention is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present invention, but is usually 0.001% by mass or more, preferably 0.01% by mass, more preferably 0.1% by mass, and usually 2% by mass, preferably 1.7% by mass, more preferably 1.5% by mass. By setting the concentration at this level, the amount of interaction with the positive and negative electrode surfaces can be optimized, and input / output characteristics can be maximized.

[0042] <1-3. Content of the Essential Compounds in the Non-Aqueous Electrolyte Solution of the Present Invention> In the nonaqueous electrolytic solution of the present invention, the ratio of the mass content of the fluorosulfonate (B) to the mass content of the compound belonging to the group (A) [(the content of the fluorosulfonate (B)] The ratio (mass) / (mass of the compound belonging to group (A)) is 1 or less. In addition, it is usually 0.0005 or more, preferably 0.001 or more, and more preferably 0.002 or more. and is preferably 0.8 or less, more preferably 0.7 or less. By setting this ratio, the balance between the amount of interaction with the positive electrode and negative electrode surfaces and the amount of lithium ions supplied can be optimized, thereby maximizing input / output characteristics. The above ratio can be applied to nonaqueous electrolyte solutions in any state, and may be nonaqueous electrolyte solutions before being introduced into an energy device or nonaqueous electrolyte solutions extracted from an energy device.

[0043] Here, the preparation of the non-aqueous electrolyte solution containing the compound belonging to group (A) and the fluorosulfonate (B) may be carried out by a known method and is not particularly limited. For example, a method of adding the compound belonging to group (A) and the fluorosulfonate (B) separately to the non-aqueous electrolyte solution, or a method of adding the compound belonging to group (A) and / or the fluorosulfonate (B) to a solvent and then adding each component a method in which a compound belonging to group (A) or a fluorosulfonate (B) is mixed into battery constituent elements such as an active material or an electrode plate, which will be described later, to construct a battery element (battery element), and then dissolve the compound belonging to group (A) or the fluorosulfonate (B) in the nonaqueous electrolyte when assembling an energy device such as a nonaqueous electrolyte secondary battery by injecting the nonaqueous electrolyte; and a method in which a compound belonging to group (A) or a compound capable of generating fluorosulfonate (B) is mixed in advance in the nonaqueous electrolyte solution or energy device to obtain an electrolyte containing the compound belonging to group (A) or the fluorosulfonate (B).

[0044] <2.Non-aqueous electrolyte> <2-1. Other electrolyte salts> The non-aqueous electrolyte solution of the present invention may contain one or more other electrolyte salts in addition to the compound belonging to group (A) and the fluorosulfonic acid salt (B). The electrolyte salt is preferably a lithium salt. Any electrolyte salt known to be used as an electrolyte salt may be used without any particular limitation, and specific examples thereof include the following:

[0045] for example, Inorganic lithium salts such as LiBF4, LiClO4, LiAlF4, LiPF6, LiSbF6, LiTaF6, and LiWF7; Lithium fluorophosphate salts other than LiPF6, such as LiPO3F and LiPO2F2; Lithium tungstate salts such as LiWOF5; Lithium carboxylates such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li; Lithium sulfonate salts such as CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li; Lithium methide salts such as (FSO2)3CLi, (CF3SO2)3CLi, (C2F5SO2)3CLi; lithium oxalate salts such as lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate; Other examples include fluorine-containing organic lithium salts such as LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2; and the like. Among these, from the viewpoint of further enhancing the effects of improving the initial input / output characteristics, input / output characteristics after durability tests such as cycle tests and high-temperature storage tests, charge / discharge rate charge / discharge characteristics, and impedance characteristics, , inorganic lithium salts, lithium fluorophosphate salts, lithium sulfonate salts, and lithium oxalate salts are preferred. Among these, LiPF6, LiBF4, LiSbF6, LiTaF6, LiPO3F, LiPO2F2, CF3SO3Li, (FSO2)3CLi, (CF3SO2)3CLi, (C2F5SO2)CLi3, lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate are particularly preferred because they have the effect of improving input / output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc.

[0046] The total concentration of the compound belonging to group (A), the fluorosulfonate (B), and other electrolyte salts in the non-aqueous electrolyte solution is not particularly limited, but is usually 8% by mass or more, preferably 8.5% by mass or more, and more preferably 9% by mass or more. The upper limit is usually 18% by mass or less, preferably 17% by mass or less, and more preferably 16% by mass or less. It is preferable that the total concentration of the compound belonging to group (A), the fluorosulfonate (B), and other electrolyte salts in the non-aqueous electrolyte solution be within the above range, because the electrical conductivity and viscosity are appropriate for battery operation.

[0047] The other electrolyte salts may be used alone or in combination of two or more. Preferred examples of combinations of two or more include LiPF6 and LiBF4, LiPF6 and LiPO2F2, LiPF6 and lithium bis(oxalato)borate, LiPF6 and lithium tetrafluorooxalatophosphate, LiPF6 and lithium difluorobis(oxalato)phosphate, LiPF6, LiBF4 and LiPO2F2, LiPF6, LiPO2F2 and lithium bis(oxalato)borate, or LiPF6, LiPO2F2 and lithium difluorobis(oxalato)phosphate, which have the effect of improving input / output characteristics, high-temperature storage characteristics, and cycle characteristics. In this case, the content of LiPF6 in the non-aqueous electrolyte is preferably 4% by mass or more, more preferably 5% by mass or more, even more preferably 6% by mass or more, and preferably 14% by mass or less, more preferably 13% by mass or less, and even more preferably 12% by mass or less. The content of LiBF4, LiPO2F2, lithium bis(oxalato)borate, or lithium difluorobis(oxalato)phosphate in the non-aqueous electrolyte is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the LiPF6 concentration is within the above preferred range, the total ion content and viscosity of the non-aqueous electrolyte are well balanced, resulting in a low internal impedance of the energy device without excessively reducing ionic conductivity. This further facilitates the development of improved input / output characteristics, cycle characteristics, and storage characteristics due to the incorporation of LiPF6.

[0048] Particularly preferred combinations of electrolytes are LiPF6 and LiPO2F2, LiPF6 and lithium bis(oxalato)borate, and LiPF6, LiPO2F2 and lithium bis(oxalato)borate. By combining these with a compound belonging to group (A) and a fluorosulfonate (B), the effects of the present invention, namely, input / output characteristics, durability such as cycle capacity and storage capacity, reduction of battery swelling and metal elution, and improved safety, can be maximized.

[0049] These electrolyte materials can be produced by conventionally known methods. Here, the preparation of the non-aqueous electrolyte solution containing the electrolyte material may be carried out by a known method and is not particularly limited. For example, there are a method of adding the electrolyte material synthesized separately to a non-aqueous electrolyte solution, a method of mixing the electrolyte material into battery components such as active materials and electrode plates described below to construct a battery element (battery element), and dissolving the electrolyte material in the non-aqueous electrolyte solution when assembling the battery by injecting the non-aqueous electrolyte solution, a method of allowing water to coexist in battery components such as active materials, electrode plates, and separators, and dissolving other electrolytes in the system when assembling a non-aqueous electrolyte secondary battery using a non-aqueous electrolyte solution containing the electrolyte material. In the present invention, any of the methods may be used.

[0050] The method for measuring the content of each electrolyte in the nonaqueous electrolyte solution and the nonaqueous electrolyte secondary battery is not particularly limited, and any known method can be used, specifically, ion chromatography, nuclear magnetic resonance spectroscopy (NMR), etc.

[0051] <2-2. Non-aqueous solvents> The nonaqueous electrolyte solution according to one embodiment of the present invention, like a general nonaqueous electrolyte solution, usually contains a nonaqueous solvent that dissolves the above-mentioned electrolyte as its main component. There are no particular limitations on the nonaqueous solvent used here, and known organic solvents can be used. Examples of organic solvents include saturated cyclic carbonates, chain carbonates, chain carboxylic acid esters, cyclic carboxylic acid esters, ether-based compounds, sulfone-based compounds, etc., but are not particularly limited thereto. These can be used alone or in combination of two or more. In one embodiment of the present invention, the non-aqueous electrolyte preferably contains one or more compounds selected from the group consisting of cyclic carbonates, chain carbonates, and chain esters.

[0052] <2-2-1. Saturated cyclic carbonates> The saturated cyclic carbonate may be one having an alkylene group having 2 to 4 carbon atoms. Specifically, examples of saturated cyclic carbonates having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate and propylene carbonate are preferred from the viewpoint of improving the battery characteristics due to the improved degree of lithium ion dissociation. The saturated cyclic carbonates may be used alone or in any combination and ratio of two or more.

[0053] The content of the saturated cyclic carbonate is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention. However, when one type is used alone, the lower limit of the content is usually 3% by volume or more, preferably 5% by volume or more, based on 100% by volume of the nonaqueous solvent. By setting the content within this range, a decrease in electrical conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte solution can be avoided, and the large-current discharge characteristics, stability with respect to the negative electrode, and cycle characteristics of the nonaqueous electrolyte secondary battery can be easily maintained within a favorable range. The upper limit is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. Setting the content within this range is preferable because it allows the viscosity of the nonaqueous electrolyte solution to be within an appropriate range, suppresses a decrease in ionic conductivity, and thereby further improves the input / output characteristics of the nonaqueous electrolyte secondary battery and further improves durability such as cycle characteristics and storage characteristics.

[0054] Furthermore, any combination of two or more saturated cyclic carbonates can be used. One preferred combination is a combination of ethylene carbonate and propylene carbonate. In this case, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99:1 to 40:60, more preferably 95:5 to 50:50. Furthermore, the lower limit of the amount of propylene carbonate in the entire nonaqueous solvent is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more. The upper limit is usually 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less. It is preferable to contain propylene carbonate within this range, as this will result in even better low-temperature properties.

[0055] <2-2-2. Chain carbonate> The chain carbonate preferably has 3 to 7 carbon atoms. Specifically, examples of chain carbonates having 3 to 7 carbon atoms include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl-n-propyl carbonate. Examples of the carbonate include methyl carbonate, n-butyl carbonate, isobutyl methyl carbonate, t-butyl methyl carbonate, ethyl n-propyl carbonate, n-butyl ethyl carbonate, isobutyl ethyl carbonate, and t-butyl ethyl carbonate. Of these, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl-n-propyl carbonate are preferred, and dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferred.

[0056] Furthermore, chain carbonates having fluorine atoms (hereinafter sometimes abbreviated as "fluorinated chain carbonate") can also be suitably used. The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, and preferably 4 or less. When the fluorinated chain carbonate has multiple fluorine atoms, they may be bonded to the same carbon or different carbons. Examples of fluorinated chain carbonates include fluorinated dimethyl carbonate derivatives, fluorinated ethyl methyl carbonate derivatives, and fluorinated diethyl carbonate derivatives.

[0057] Examples of fluorinated dimethyl carbonate derivatives include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis(fluoromethyl)carbonate, bis(difluoro)methyl carbonate, and bis(trifluoromethyl)carbonate. Examples of fluorinated ethyl methyl carbonate derivatives include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, 2,2-difluoroethyl fluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, and ethyl trifluoromethyl carbonate. Examples of fluorinated diethyl carbonate derivatives include ethyl-(2-fluoroethyl)carbonate, ethyl-(2,2-difluoroethyl)carbonate, bis(2-fluoroethyl)carbonate, ethyl-(2,2,2-trifluoroethyl)carbonate, 2,2-difluoroethyl-2'-fluoroethylcarbonate, bis(2,2-difluoroethyl)carbonate, 2,2,2-trifluoroethyl-2'-fluoroethylcarbonate, 2,2,2-trifluoroethyl-2',2'-difluoroethylcarbonate, and bis(2,2,2-trifluoroethyl)carbonate.

[0058] The chain carbonate may be used alone or in any combination of two or more kinds in any ratio. The content of the chain carbonate is not particularly limited, but is usually 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more, based on 100% by volume of the nonaqueous solvent. It is also usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the content of the chain carbonate within the above range, the viscosity of the nonaqueous electrolyte solution can be set within an appropriate range, a decrease in ionic conductivity can be suppressed, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery can be easily set within good ranges. Furthermore, a decrease in electrical conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte solution can be avoided, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery can be easily set within good ranges.

[0059] Furthermore, by combining a specific chain carbonate with ethylene carbonate in a specific content, the battery performance can be significantly improved. For example, when dimethyl carbonate and ethyl methyl carbonate are selected as the specific chain carbonates, the content of ethylene carbonate is not particularly limited, and the effects of the present invention can be achieved. The content of dimethyl carbonate is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. The content of ethyl methyl carbonate is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. By setting the content within the above range, the low-temperature deposition temperature of the electrolyte is lowered, and the viscosity of the nonaqueous electrolyte is also lowered, improving ionic conductivity and allowing high input / output even at low temperatures.

[0060] <2-2-3. Chain carboxylic acid esters> Examples of the chain carboxylic acid ester include those having a total of 3 to 7 carbon atoms in the structural formula. Specific examples include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl isobutyrate, and isopropyl isobutyrate. Among these, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, methyl butyrate, and ethyl butyrate are preferred from the viewpoints of improving ionic conductivity by reducing viscosity and suppressing battery swelling during endurance such as cycling and storage.

[0061] The content of the chain carboxylic acid ester is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but is usually 5% by volume or more, preferably 8% by volume or more, and usually 80% by volume or less, preferably 70% by volume or less, based on 100% by volume of the nonaqueous solvent. When the content of the chain carboxylic acid ester is within the above range, the electrical conductivity of the nonaqueous electrolyte is improved, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery are easily improved. Furthermore, an increase in negative electrode resistance is suppressed, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery are easily maintained within a favorable range.

[0062] When a chain carboxylic acid ester is used, it is preferably used in combination with a cyclic carbonate, and more preferably a combination of a cyclic carbonate and a chain carbonate. For example, when a cyclic carbonate and a chain carboxylic acid ester are used in combination, the content of the cyclic carbonate is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present invention, but is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less, preferably 40% by volume or less, and the content of the chain carboxylic acid ester is usually 20% by volume or more, preferably 30% by volume or more, and usually 55% by volume or less, preferably 50% by volume or less. Furthermore, when a cyclic carbonate, a chain carbonate, and a chain carboxylic acid ester are used in combination, the content of the cyclic carbonate is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present invention, but is usually 15% by volume or more, preferably 20% by volume, and usually 45% by volume or less, preferably 40% by volume or less, and the content of the chain carbonate is usually 25% by volume or more, preferably 30% by volume or more, and usually 84% by volume or less, preferably 80% by volume or less. By setting the content within the above range, the low-temperature deposition temperature of the electrolyte is lowered while the viscosity of the nonaqueous electrolytic solution is also lowered, improving ionic conductivity, and higher input / output can be obtained even at low temperatures, which is preferable from the viewpoint of further reducing battery swelling.

[0063] <2-2-4. Cyclic carboxylic acid esters> Examples of cyclic carboxylic acid esters include those having a total of 3 to 12 carbon atoms in their structural formula. Specific examples include gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, epsilon-caprolactone, etc. Among these, gamma-butyrolactone is particularly preferred from the viewpoint of improving the battery characteristics resulting from the improvement in the degree of dissociation of lithium ions.

[0064] The content of the cyclic carboxylic acid ester is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but is usually 3% by volume or more, preferably 5% by volume or more, and usually 60% by volume or less, preferably 50% by volume or less, based on 100% by volume of the nonaqueous solvent. Setting the content of the cyclic carboxylic acid ester within this range improves the electrical conductivity of the nonaqueous electrolyte solution, making it easier to improve the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery. Furthermore, it is possible to keep the viscosity of the nonaqueous electrolyte solution within an appropriate range, avoid a decrease in electrical conductivity, suppress an increase in negative electrode resistance, and make it easier to keep the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery within good ranges.

[0065] <2-2-5. Ether compounds> As the ether-based compound, a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms are preferred. Examples of the chain ethers having 3 to 10 carbon atoms include diethyl ether, di(2-fluoroethyl) ether, di(2,2-difluoroethyl) ether, di(2,2,2-trifluoroethyl) ether, ethyl(2-fluoroethyl) ether, ethyl(2,2,2-trifluoroethyl) ether, ethyl(1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl)(2,2,2-trifluoroethyl) ether, (2-fluoroethyl)(1,1,2,2-tetrafluoroethyl) ether, and (2,2,2-trifluoroethyl). Ethyl)(1,1,2,2-tetrafluoroethyl) ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-propyl) ether, ethyl (2,2,3,3-tetrafluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n-propyl ether, (2-fluoroethyl)(3-fluoro-n-propyl) ether, (2-fluoroethyl)(3,3,3-trifluoro-n-propyl (2-fluoroethyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (2-fluoroethyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-trifluoroethyl-n-propyl ether, (2,2,2-trifluoroethyl)(3-fluoro-n-propyl) ether, (2,2,2-trifluoroethyl)(3,3,3-trifluoro-n-propyl) ether, (2,2,2-trifluoroethyl)(2,2,3,3-tetrafluoro-n-propyl) ether , (2,2,2-trifluoroethyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, 1,1,2,2-tetrafluoroethyl-n-propyl ether, (1,1,2,2-tetrafluoroethyl)(3-fluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (1,1,2,2-tetrafluoroethyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-propyl ether, (n-propyl)(3-fluoro-n-propyl) ether, (n-propyl)(3,3,3-trifluoro-n-propyl) ether, (n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, di(3-fluoro-n-propyl) ether, (3-fluoro-n-propyl)(3,3,3 -trifluoro-n-propyl) ether, (3-fluoro-n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (3-fluoro-n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, di(3,3,3-trifluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl)(2,2,3,3-tetrafluoro-n-propyl) ether, (3,3,3-trifluoro-n-propyl)(2,2,3, ,3,3-pentafluoro-n-propyl) ether, di(2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl)(2,2,3,3,3-pentafluoro-n-propyl) ether, di(2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, methoxyethoxymethane, methoxy(2-fluoroethoxy)methane, methoxy(2,2,2-trifluoroethoxy)methane, methoxy(1,1,2,2-tetrafluoroethoxy)methane (2-fluoroethoxy)methane, diethoxymethane, ethoxy(2-fluoroethoxy)methane, ethoxy(2,2,2-trifluoroethoxy)methane, ethoxy(1,1,2,2-tetrafluoroethoxy)methane, di(2-fluoroethoxy)methane, (2-fluoroethoxy)(2,2,2-trifluoroethoxy)methane, (2-fluoroethoxy)(1,1,2,2-tetrafluoroethoxy)methane di(2,2,2-trifluoroethoxy)methane, (2,2,2-trifluoroethoxy)methane, (2,2,2-trifluoroethoxy)(1,1,2,2-trifluoroethoxy)methane (tetrafluoroethoxy)methane, di(1,1,2,2-tetrafluoroethoxy)methane, dimethoxyethane, methoxyethoxyethane, methoxy(2-fluoroethoxy)ethane, methoxy(2,2,2-trifluoroethoxy)ethane, methoxy(1,1,2,2-tetrafluoroethoxy)ethane, diethoxyethane, ethoxy(2-fluoroethoxy)ethane, ethoxy(2,2,2-trifluoroethoxy)ethane, ethoxy(1,1,2,2-tetrafluoroethoxy)ethane, di(2-fluoroethoxy) Examples include ethane, (2-fluoroethoxy)(2,2,2-trifluoroethoxy)ethane, (2-fluoroethoxy)(1,1,2,2-tetrafluoroethoxy)ethane, di(2,2,2-trifluoroethoxy)ethane, (2,2,2-trifluoroethoxy)(1,1,2,2-tetrafluoroethoxy)ethane, di(1,1,2,2-tetrafluoroethoxy)ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether.

[0066] Examples of cyclic ethers having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane, and fluorinated compounds thereof. Among these, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether are preferred because they have a high ability to solvate lithium ions and improve ionic dissociation. Dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are particularly preferred because they have low viscosity and provide high ionic conductivity.

[0067] The content of the ether-based compound is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention. However, it is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less, based on 100% by volume of the nonaqueous solvent. When the content of the ether-based compound is within the above-mentioned preferred range, it is easy to ensure the effect of improving the lithium ion dissociation degree of the chain ether and improving ionic conductivity due to reduced viscosity. Furthermore, when the negative electrode active material is a carbonaceous material, the phenomenon of co-insertion of the chain ether with lithium ions can be suppressed, thereby allowing the input / output characteristics and charge / discharge rate characteristics to be within appropriate ranges.

[0068] <2-2-6. Sulfone compounds> The sulfone-based compound is preferably a cyclic sulfone having 3 to 6 carbon atoms, or a chain sulfone having 2 to 6 carbon atoms. The number of sulfonyl groups in one molecule is preferably 1 or 2. Examples of cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones; and disulfone compounds such as trimethylene diamines. Examples of such sulfones include sulfones, tetramethylene disulfones, and hexamethylene disulfones. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0069] The sulfolanes are preferably sulfolane and / or sulfolane derivatives (hereinafter, sulfolane may also be abbreviated as "sulfolanes"). The sulfolane derivatives are preferably those in which one or more hydrogen atoms bonded to the carbon atoms constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group. Among these, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methylsulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane Perfluorolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoromethylsulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3-(trifluoromethyl)sulfolane, 3-fluoro-3-(trifluoromethyl)sulfolane, 4-fluoro-3-(trifluoromethyl)sulfolane, 5-fluoro-3-(trifluoromethyl)sulfolane, and the like are preferred because of their high ionic conductivity and high input / output.

[0070] Examples of chain sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, n-propyl ethyl sulfone, di-n-propyl sulfone, isopropyl methyl sulfone, isopropyl ethyl sulfone, diisopropyl sulfone, n-butyl methyl sulfone, n-butyl ethyl sulfone, t-butyl methyl sulfone, t-butyl ethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, and perfluoroethyl methyl sulfone. Examples thereof include fluoromethyl-n-propyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, di(trifluoroethyl) sulfone, perfluorodiethyl sulfone, fluoromethyl-n-propyl sulfone, difluoromethyl-n-propyl sulfone, trifluoromethyl-n-propyl sulfone, fluoromethyl isopropyl sulfone, difluoromethyl isopropyl sulfone, trifluoromethyl isopropyl sulfone, trifluoroethyl-n-propyl sulfone, trifluoroethyl isopropyl sulfone, pentafluoroethyl-n-propyl sulfone, pentafluoroethyl isopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, pentafluoroethyl-n-butyl sulfone, and pentafluoroethyl-t-butyl sulfone.

[0071] Among these, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, n-propyl methyl sulfone, isopropyl methyl sulfone, n-butyl methyl sulfone, t-butyl methyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, monofluoroethyl methyl sulfone, difluoroethyl methyl sulfone, trifluoroethyl methyl sulfone, pentafluoroethyl methyl sulfone, ethyl monofluoromethyl sulfone, ethyl difluoromethyl sulfone, ethyl trifluoromethyl sulfone, ethyl trifluoroethyl sulfone, ethyl pentafluoroethyl sulfone, trifluoromethyl-n-propyl sulfone, trifluoromethyl Trifluoroisopropyl sulfone, trifluoroethyl-n-butyl sulfone, trifluoroethyl-t-butyl sulfone, trifluoromethyl-n-butyl sulfone, or trifluoromethyl-t-butyl sulfone is preferred in terms of high ionic conductivity and high input / output.

[0072] The content of the sulfone compound is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but is usually 0.3 vol% or more, preferably 0.5 vol% or more, more preferably 1 vol% or more, and usually 40 vol% or less, preferably 35 vol% or less, more preferably 30 vol% or less, based on 100 vol% of the nonaqueous solvent. If the content of the sulfone compound is within the above range, it is easy to obtain an effect of improving durability such as cycle characteristics and storage characteristics, and it is also possible to keep the viscosity of the nonaqueous electrolyte within an appropriate range, avoid a decrease in electrical conductivity, and keep the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte secondary battery within appropriate ranges.

[0073] <2-3. Auxiliaries> The nonaqueous electrolyte solution of the present invention may further contain various auxiliary agents, which will be described in detail below.

[0074] <2-3-1. Carbonates Having at Least Either a Carbon-Carbon Unsaturated Bond or a Fluorine Atom> The nonaqueous electrolyte solution according to one embodiment of the present invention may further contain at least one of a carbonate having a carbon-carbon unsaturated bond and a carbonate having a fluorine atom. The carbonate having a carbon-carbon unsaturated bond is preferably a cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter, sometimes abbreviated as "unsaturated cyclic carbonate"). The carbonate having a fluorine atom is preferably a cyclic carbonate having a fluorine atom.

[0075] The cyclic carbonate having a carbon-carbon unsaturated bond is not particularly limited, and any carbonate having a carbon-carbon unsaturated bond can be used, as long as it is a cyclic carbonate having a carbon-carbon unsaturated bond.In addition, cyclic carbonates having a substituent with an aromatic ring are also included in the cyclic carbonate having a carbon-carbon unsaturated bond.The method for producing the unsaturated cyclic carbonate is not particularly limited, and it can be produced by any known method. Examples of unsaturated cyclic carbonates include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, phenyl carbonates, vinyl carbonates, and allyl carbonates.

[0076] Examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, and allyl vinylene carbonate. Specific examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, phenyl ethylene carbonate, 4,5-diphenyl ethylene carbonate, ethynyl ethylene carbonate, and 4,5-diethynyl ethylene carbonate. Among these, vinylene carbonates and ethylene carbonate substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond are preferred, and in particular, vinylene carbonate, 4,5-diphenylvinylene carbonate, 4,5-dimethylvinylene carbonate, vinylethylene carbonate, or ethynylethylene carbonate are more preferably used because they form a stable interface protective coating.

[0077] The molecular weight of the unsaturated cyclic carbonate is not particularly limited, and may be any molecular weight as long as it does not significantly impair the effects of the present invention. The molecular weight of the unsaturated cyclic carbonate is usually 50 or more, preferably 80 or more, and usually 250 or less, preferably 150 or less. Within these ranges, the solubility of the unsaturated cyclic carbonate in the nonaqueous electrolyte solution can be easily ensured, and the effects of the present invention can be easily exhibited. The unsaturated cyclic carbonate may be used alone or in any combination and ratio of two or more. The content of the unsaturated cyclic carbonate is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention. The content of the unsaturated cyclic carbonate is typically 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, based on 100% by mass of the nonaqueous electrolyte solution. The content within the above ranges facilitates the nonaqueous electrolyte secondary battery to exhibit sufficient high-temperature storage characteristics and improved cycle characteristics.

[0078] The cyclic carbonate having a fluorine atom (hereinafter sometimes abbreviated as "fluorinated cyclic carbonate") is not particularly limited as long as it is a cyclic carbonate having a fluorine atom. The fluorinated cyclic carbonate includes a derivative of a cyclic carbonate having an alkylene group having 2 to 6 carbon atoms, such as an ethylene carbonate derivative. The ethylene carbonate derivative includes, for example, a fluorinated product of ethylene carbonate or ethylene carbonate substituted with an alkyl group (e.g., an alkyl group having 1 to 4 carbon atoms), and among these, those having 1 to 8 fluorine atoms are preferred.

[0079] Specific examples include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, and 4,4-difluoro-5,5-dimethylethylene carbonate. Among these, at least one selected from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4,5-difluoro-4,5-dimethylethylene carbonate is more preferred in that it provides high ionic conductivity and favorably forms an interface protective coating.

[0080] The fluorinated cyclic carbonate may be used alone or in any combination and ratio of two or more. The content of the fluorinated cyclic carbonate is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present invention, but is usually 0.001% by mass or more, preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, relative to 100% by mass of the nonaqueous electrolyte solution. The content is usually 8% by mass or less, preferably 6% by mass or less, and more preferably 5% by mass or less. Within this range, the nonaqueous electrolyte secondary battery is likely to exhibit sufficient cycle characteristics and high-temperature storage characteristics. Within this range, the nonaqueous electrolyte secondary battery is likely to exhibit sufficient cycle characteristics and high-temperature storage characteristics.

[0081] The fluorinated cyclic carbonate may be used as an auxiliary agent for the non-aqueous electrolyte solution or as a non-aqueous solvent. When used as a non-aqueous solvent, the content of the fluorinated cyclic carbonate is usually 8% by mass or more, preferably 10% by mass or more, more preferably 12% by mass or more, and usually 85% by mass or less, preferably 10% by mass or more, based on 100% by mass of the non-aqueous electrolyte solution. is 80% by mass or less, more preferably 75% by mass or less. Within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and a decrease in the discharge capacity retention rate is likely to be avoided.

[0082] In the nonaqueous electrolyte solution according to one embodiment of the present invention, the carbonate having at least one of a carbon-carbon unsaturated bond and a fluorine atom is preferably at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, ethynyl ethylene carbonate, and fluoroethylene carbonate.

[0083] <2-3-2. Fluorinated unsaturated cyclic carbonates> As the fluorinated cyclic carbonate, a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter, sometimes abbreviated as "fluorinated unsaturated cyclic carbonate") can be used. The fluorinated unsaturated cyclic carbonate is not particularly limited. Among them, those having one or two fluorine atoms are preferred. The method for producing the fluorinated unsaturated cyclic carbonate is not particularly limited, and it can be produced by any known method. Examples of the fluorinated unsaturated cyclic carbonate include vinylene carbonate derivatives and ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond.

[0084] Examples of vinylene carbonate derivatives include 4-fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, and 4,5-difluoroethylene carbonate. Examples of ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, and 4,5-difluoro-4-phenylethylene carbonate.

[0085] The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and may be any as long as it does not significantly impair the effects of the present invention. The molecular weight of the fluorinated unsaturated cyclic carbonate is usually 50 or more, preferably 80 or more, and usually 250 or less, preferably 150 or less. Within this range, the solubility of the fluorinated cyclic carbonate in the non-aqueous electrolyte solution is easily ensured, and the effects of the present invention are easily exhibited.

[0086] The fluorinated unsaturated cyclic carbonate may be used alone or in any combination and ratio of two or more. The amount of the fluorinated unsaturated cyclic carbonate is not particularly limited, and may be any amount as long as it does not significantly impair the effects of the present invention. The content of the fluorinated unsaturated cyclic carbonate is typically 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.2% by mass or more, relative to 100% by mass of the nonaqueous electrolyte solution, and is typically 5% by mass or less, preferably 4% by mass or less, and more preferably 3% by mass or less. Within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics.

[0087] <2-3-3. Compounds containing a cyano group> In the nonaqueous electrolyte solution of the present invention, the compound having a cyano group that can be used is not particularly limited as long as it has a cyano group in the molecule, but is more preferably a compound represented by the following general formula (4): The method for producing the compound having a cyano group is not particularly limited, and it can be produced by any known method. [ka]

[0088] In general formula (4), T represents an organic group composed of atoms selected from the group consisting of carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorus, and halogen atoms, and U represents a pentavalent organic group having 1 to 10 carbon atoms which may have a substituent. V is an integer of 1 or greater, and when V is 2 or greater, Ts may be the same or different. The molecular weight of the compound having a cyano group is not particularly limited and may be any as long as it does not significantly impair the effects of the present invention. The molecular weight of the compound having a cyano group is usually 40 or more, preferably 45 or more, more preferably 50 or more, and usually 200 or less, preferably 180 or less, more preferably 170 or less. Within this range, the solubility of the compound having a cyano group in the non-aqueous electrolyte solution can be easily ensured, and the effects of the present invention can be easily achieved.

[0089] Specific examples of the compound represented by general formula (4) include: Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 2-methylbutyronitrile, trimethylacetonitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitrile, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile, 2-hexenenitrile, fluoroacetonitrile, difluoro compounds having one cyano group, such as acetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3-difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3'-oxydipropionitrile, 3,3'-thiodipropionitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, and pentafluoropropionitrile; Compounds having two cyano groups, such as malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, dodecanedinitrile, methylmalononitrile, ethylmalononitrile, isopropylmalononitrile, tert-butylmalononitrile, methylsuccinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, trimethylsuccinonitrile, tetramethylsuccinonitrile, 3,3'-(ethylenedioxy)dipropionitrile, and 3,3'-(ethylenedithio)dipropionitrile; Compounds with three cyano groups, such as 1,2,3-tris(2-cyanoethoxy)propane and tris(2-cyanoethyl)amine; Cyanate compounds such as methyl cyanate, ethyl cyanate, propyl cyanate, butyl cyanate, pentyl cyanate, hexyl cyanate, and heptyl cyanate; sulfur-containing compounds such as methyl thiocyanate, ethyl thiocyanate, propyl thiocyanate, butyl thiocyanate, pentyl thiocyanate, hexyl thiocyanate, heptyl thiocyanate, methanesulfonyl cyanide, ethanesulfonyl cyanide, propanesulfonyl cyanide, butanesulfonyl cyanide, pentanesulfonyl cyanide, hexanesulfonyl cyanide, heptanesulfonyl cyanide, methyl sulfurocyanidate, ethyl sulfurocyanidate, propyl sulfurocyanidate, butyl sulfurocyanidate, pentyl sulfurocyanidate, hexyl sulfurocyanidate, and heptyl sulfurocyanidate; Cyanodimethylphosphine, cyanodimethylphosphine oxide, cyanomethylphosphine phosphorus-containing compounds such as methyl phosphate, methyl cyanomethylphosphinite, dimethylphosphinate cyanide, dimethylphosphinite cyanide, dimethyl cyanophosphonate, dimethyl cyanophosphonite, cyanomethyl methylphosphonate, cyanomethyl methylphosphonite, cyanodimethyl phosphate, cyanodimethyl phosphite, etc.; etc.

[0090] Of these, acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, crotononitrile, 3-methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, or dodecanedinitrile is preferred from the viewpoint of improving storage properties, and malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile, undecanedinitrile, or dodecanedinitrile, which have two cyano groups, is more preferred.

[0091] The compound having a cyano group may be used alone or in any combination and ratio of two or more. There is no limitation on the content of the compound having a cyano group relative to the entire non-aqueous electrolyte solution of the present invention, and it is optional as long as it does not significantly impair the effects of the present invention. However, it is usually contained at a concentration of 0.001 mass% or more, preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.3 mass% or more, and usually 10 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less, relative to the non-aqueous electrolyte solution of the present invention. When the above range is satisfied, effects such as input / output characteristics, charge / discharge rate characteristics, cycle characteristics, high-temperature storage characteristics, etc. are further improved.

[0092] <2-3-4. Isocyanate compounds> In the nonaqueous electrolyte solution of the present invention, the compound having an isocyanate group (hereinafter sometimes abbreviated as "isocyanate compound") that can be used is not particularly limited as long as it is a compound having an isocyanate group in the molecule. As the isocyanate compound, a diisocyanate compound having two isocyanate groups in the molecule is preferred.

[0093] <2-3-4-1. Diisocyanate compounds> The diisocyanate compound that can be used in the nonaqueous electrolyte solution of the present invention is preferably a compound that has nitrogen atoms only in the isocyanate groups in the molecule and is represented by the following general formula (5). [ka]

[0094] In the above general formula (5), X may contain a cyclic structure and is an organic group having from 1 to 15 carbon atoms. The number of carbon atoms in X is usually 2 or more, preferably 3 or more, more preferably 4 or more, and is usually 14 or less, preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less. In the general formula (5), X is particularly preferably an organic group having 4 to 15 carbon atoms and at least one cycloalkylene group or aromatic hydrocarbon group having 4 to 6 carbon atoms. In this case, the hydrogen atoms on the cycloalkylene group may be substituted with a methyl group or an ethyl group. The diisocyanate compound having the cyclic structure is a molecule due to its steric bulkiness, and therefore side reactions are less likely to occur on the positive electrode, resulting in improved cycle characteristics and high-temperature storage characteristics. Here, the bonding site of the group bonding to the cycloalkylene group or aromatic hydrocarbon group is not particularly limited, and may be any of the meta position, para position, or ortho position, but the meta position or para position is preferred. An appropriate inter-coating crosslinking distance is advantageous for lithium ion conductivity and is preferable because it facilitates reducing resistance. In addition, the cycloalkylene group is preferably a cyclopentylene group or a cyclohexylene group from the viewpoint that the diisocyanate compound itself is less likely to undergo side reactions, and a cyclohexylene group is more preferable because it facilitates reducing resistance due to the influence of molecular mobility. In addition, it is preferable that an alkylene group having 1 to 3 carbon atoms is present between the cycloalkylene group or aromatic hydrocarbon group and the isocyanate group. The presence of the alkylene group increases the steric bulkiness, making side reactions less likely to occur on the positive electrode. Furthermore, if the alkylene group has 1 to 3 carbon atoms, the proportion of the isocyanate group relative to the total molecular weight does not change significantly, making it easier to significantly exhibit the effects of the present invention.

[0095] The molecular weight of the diisocyanate compound represented by the general formula (5) is not particularly limited and may be any molecular weight as long as it does not significantly impair the effects of the present invention. The molecular weight is usually 80 or more, preferably 115 or more, more preferably 170 or more, and usually 300 or less, preferably 230 or less. Within this range, the solubility of the diisocyanate compound in the nonaqueous electrolyte solution can be easily ensured, and the effects of the present invention can be easily achieved.

[0096] Specific examples of the diisocyanate compound include: cycloalkane ring-containing diisocyanates such as 1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane-2,2'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, dicyclohexylmethane-3,3'-diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate; 1,2-Phenylene diisocyanate, 1,3-Phenylene diisocyanate, 1,4-Phenylene diisocyanate, Tolylene-2,3-diisocyanate, Tolylene-2,4-diisocyanate, Tolylene-2,5-diisocyanate, Tolylene-2,6-diisocyanate, Tolylene-3,4-diisocyanate, Tolylene-3,5-diisocyanate, 1,2-Bis(isocyanatomethyl)benzene, 1,3-Bis(isocyanatomethyl)benzene, 1,4-Bis(isocyanatomethyl)benzene, 2,4-Diisocyanatobiphenyl, 2,6-Diisocyanatobiphenyl, 2,2'-Diisocyanatobiphenyl, 3,3'-Diisocyanatobiphenyl, 4,4'-Diisocyanatobiphenyl aromatic ring-containing diisocyanates such as 4,4'-diisocyanato-2-methylbiphenyl, 4,4'-diisocyanato-3-methylbiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 4,4'-diisocyanatodiphenylmethane, 4,4'-diisocyanato-2-methyldiphenylmethane, 4,4'-diisocyanato-3-methyldiphenylmethane, 4,4'-diisocyanato-3,3'-dimethyldiphenylmethane, 1,5-diisocyanatonaphthalene, 1,8-diisocyanatonaphthalene, 2,3-diisocyanatonaphthalene, 1,5-bis(isocyanatomethyl)naphthalene, 1,8-bis(isocyanatomethyl)naphthalene, and 2,3-bis(isocyanatomethyl)naphthalene; Examples include:

[0097] Among these, 1,2-diisocyanatocyclopentane, 1,3-diisocyanatocyclopentane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,2-bis(

[0033] Preferably, 1,3-bis(isocyanatomethyl)benzene, 1,4-bis(isocyanatomethyl)benzene, 2,4-diisocyanatobiphenyl, or 2,6-diisocyanatobiphenyl is used because it forms a denser composite coating on the negative electrode, thereby improving battery durability. Among these, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,2-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanatomethyl)benzene, and 1,4-bis(isocyanatomethyl)benzene are more preferred because, due to the symmetry of their molecules, a coating that is advantageous for lithium ion conductivity is formed on the negative electrode, thereby further improving the battery characteristics. The above-mentioned diisocyanate compounds may be used alone or in any combination of two or more in any ratio.

[0098] The content of the diisocyanate compound that can be used in the non-aqueous electrolyte solution of the present invention is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.3% by mass or more, and is usually 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less, relative to the non-aqueous electrolyte solution of the present invention. If the content is within the above range, durability in cycles, storage, etc. can be improved, and the effects of the present invention can be fully exerted. The method for producing the diisocyanate compound is not particularly limited, and any known method can be selected for production. Alternatively, commercially available products may be used.

[0099] <2-3-4-2. Isocyanate compounds other than diisocyanate compounds> The non-aqueous electrolyte solution of the present invention may contain an isocyanate compound other than a diisocyanate compound. Specific examples of isocyanate compounds other than a diisocyanate compound that can be used in the non-aqueous electrolyte solution of the present invention will be described below. Specific examples of the isocyanate compound include: Hydrocarbon monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, butyl isocyanate, t-butyl isocyanate, pentyl isocyanate, hexyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, and fluorophenyl isocyanate; Monoisocyanate compounds having a carbon-carbon unsaturated bond, such as vinyl isocyanate, allyl isocyanate, ethynyl isocyanate, and propynyl isocyanate; Isocyanate compounds such as (ortho-, meta-, para-)toluenesulfonyl isocyanate, benzenesulfonyl isocyanate, fluorosulfonyl isocyanate, phenoxysulfonyl isocyanate, pentafluorophenoxysulfonyl isocyanate, and methoxysulfonyl isocyanate; etc.

[0100] The isocyanate compounds described above may be used alone or in any combination of two or more in any ratio. The amount of the isocyanate compound relative to the total amount of the nonaqueous electrolyte solution of the present invention is not limited, and may be any amount as long as it does not significantly impair the effects of the present invention. The amount is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, particularly preferably 1% by mass or less, and most preferably 0.5% by mass or less, relative to the total amount of the nonaqueous electrolyte solution of the present invention. When the content is within the above range, durability in cycles, storage, etc. can be improved, and the effects of the present invention can be fully exhibited. The method for producing the isocyanate compound is not particularly limited, and any known method may be selected. Alternatively, commercially available products may be used.

[0101] <2-3-5. Carboxylic acid anhydrides> In the non-aqueous electrolyte solution of the present invention, the carboxylic acid anhydride that can be used is preferably a compound represented by the following general formula (6): The method for producing the carboxylic acid anhydride is not particularly limited, and any known method can be selected to produce the carboxylic acid anhydride. [ka]

[0102] In general formula (6), R 9 and R 10 R each independently represents a hydrocarbon group having 1 to 15 carbon atoms, which may have a substituent. 9 and R 10 may be bonded to each other to form a ring structure. R 9 and R 10is not particularly limited in type as long as it is a monovalent hydrocarbon group. For example, it may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or may be a group in which an aliphatic hydrocarbon group and an aromatic hydrocarbon group are bonded. The aliphatic hydrocarbon group may be a saturated hydrocarbon group or may contain an unsaturated bond (a carbon-carbon double bond or a carbon-carbon triple bond). Furthermore, the aliphatic hydrocarbon group may be either chain-like or cyclic, and if it is chain-like, it may be linear or branched. Furthermore, it may be a group in which a chain-like group and a cyclic group are bonded. Note that R 9 and R 10 may be the same as or different from each other.

[0103] Also, R 9 and R 10 When they bond to each other to form a ring structure, R 9 and R 10 The hydrocarbon group formed by bonding together is divalent. The type of divalent hydrocarbon group is not particularly limited. That is, it may be an aliphatic group or an aromatic group, or may be a group in which an aliphatic group and an aromatic group are bonded. In the case of an aliphatic group, it may be a saturated group or an unsaturated group. Furthermore, it may be a chain group or a cyclic group, and in the case of a chain group, it may be a linear group or a branched group. Furthermore, it may be a group in which a chain group and a cyclic group are bonded. Also, R 9 and R 10 When the hydrocarbon group has a substituent, the type of the substituent is not particularly limited as long as it does not contradict the spirit of the present invention, but examples thereof include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, preferably fluorine atoms. Alternatively, examples of the substituent other than halogen atoms include substituents having functional groups such as ester groups, cyano groups, carbonyl groups, and ether groups, preferably cyano groups and carbonyl groups. 9 and R 10 The hydrocarbon group may have only one of these substituents or may have two or more of these substituents. When the hydrocarbon group has two or more substituents, the substituents may be the same or different from each other.

[0104] R 9 and R10 The number of carbon atoms in each hydrocarbon group of R is usually 1 or more, and usually 15 or less, preferably 12 or less, more preferably 10 or less, and even more preferably 9 or less. 9 and R 10 When R and R are bonded to each other to form a divalent hydrocarbon group, the number of carbon atoms in the divalent hydrocarbon group is usually 1 or more and usually 15 or less, preferably 13 or less, more preferably 10 or less, and even more preferably 8 or less. 9 and R 10 If the hydrocarbon group has a substituent containing a carbon atom, the substituent is included in R 9 and R 10 It is preferable that the total number of carbon atoms falls within the above range.

[0105] Next, specific examples of the carboxylic acid anhydride (hereinafter sometimes abbreviated as "acid anhydride") represented by the above general formula (6) will be explained. In the following examples, the term "analog" is used. refers to an acid anhydride obtained by replacing a part of the structure of the exemplified acid anhydride with another structure within the scope of the present invention, and examples thereof include a dimer, trimer, tetramer, etc. composed of a plurality of acid anhydrides, structural isomers such as those having the same number of carbon atoms in the substituent but having a branched chain, and those in which the substituent is bonded to the acid anhydride at a different position.

[0106] First, R 9 and R 10 Specific examples of acid anhydrides in which are the same are listed below. R 9 and R 10is a chain alkyl group, include acetic anhydride, propionic anhydride, butanoic anhydride, 2-methylpropionic anhydride, 2,2-dimethylpropionic anhydride, 2-methylbutanoic anhydride, 3-methylbutanoic anhydride, 2,2-dimethylbutanoic anhydride, 2,3-dimethylbutanoic anhydride, 3,3-dimethylbutanoic anhydride, 2,2,3-trimethylbutanoic anhydride, 2,3,3-trimethylbutanoic anhydride, 2,2,3,3-tetramethylbutanoic anhydride, 2-ethylbutanoic anhydride, and the like, and analogs thereof. R 9 and R 10 Specific examples of acid anhydrides in which is a cyclic alkyl group include cyclopropanecarboxylic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, and the like, and analogs thereof.

[0107] R 9 and R 10 is an alkenyl group, acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 2,3,3-trimethylacrylic anhydride, 2-phenylacrylic anhydride, 3-phenylacrylic anhydride, 2,3-diphenylacrylic anhydride, 3,3-diphenylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, 2,2-dimethyl-3-butenoic anhydride, 3-methyl-3-butenoic anhydride, 2-methyl-3-methyl-3-butenoic anhydride, 2,2-dimethyl-3-methyl-3-butenoic anhydride, 3-pentenoic anhydride, 4-pentenoic anhydride, 2-cyclopentenecarboxylic anhydride, 3-cyclopentenecarboxylic anhydride, 4-cyclopentenecarboxylic anhydride, and the like, and analogs thereof. R 9 and R 10 Specific examples of acid anhydrides in which is an alkynyl group include propynoic anhydride, 3-phenylpropynoic anhydride, 2-butynoic anhydride, 2-pentynoic anhydride, 3-butynoic anhydride, 3-pentynoic anhydride, 4-pentynoic anhydride, and analogs thereof. R 9 and R 10 is an aryl group, include benzoic anhydride, 4-methylbenzoic anhydride, 4-ethylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 2-methylbenzoic anhydride, 2,4,6-trimethylbenzoic anhydride, 1-naphthalenecarboxylic anhydride, 2-naphthalenecarboxylic anhydride, and analogs thereof.

[0108] Also, R 9 and R 10 As examples of acid anhydrides in which the halogen atoms are substituted, examples of acid anhydrides in which the halogen atoms are substituted mainly with fluorine atoms are given below, but acid anhydrides obtained by substituting some or all of these fluorine atoms with chlorine atoms, bromine atoms, or iodine atoms are also included in the exemplified compounds. R 9 and R 10 is a chain alkyl group substituted with a halogen atom, examples of which include fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, 2-fluoropropionic anhydride, 2,2-difluoropropionic anhydride, 2,3-difluoropropionic anhydride, 2,2,3-trifluoropropionic anhydride, 2,3,3-trifluoropropionic anhydride, 2,2,3,3-tetrapropionic anhydride, 2,3,3,3-tetrapropionic anhydride, 3-fluoropropionic anhydride, 3,3-difluoropropionic anhydride, 3,3,3-trifluoropropionic anhydride, perfluoropropionic anhydride, and analogs thereof. R 9 and R 10 As an example of an acid anhydride, Examples of the fluorocyclopentanecarboxylic anhydride include 2-fluorocyclopentanecarboxylic anhydride, 3-fluorocyclopentanecarboxylic anhydride, 4-fluorocyclopentanecarboxylic anhydride, and the like, and their analogs. R 9 and R 10Examples of acid anhydrides in which is an alkenyl group substituted with a halogen atom include 2-fluoroacrylic anhydride, 3-fluoroacrylic anhydride, 2,3-difluoroacrylic anhydride, 3,3-difluoroacrylic anhydride, 2,3,3-trifluoroacrylic anhydride, 2-(trifluoromethyl)acrylic anhydride, 3-(trifluoro Examples of the acrylic anhydride include 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3-bis(trifluoromethyl)acrylic anhydride, 2,3,3-tris(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 3-(4-fluorophenyl)acrylic anhydride, 2,3-bis(4-fluorophenyl)acrylic anhydride, 3,3-bis(4-fluorophenyl)acrylic anhydride, 2-fluoro-3-butenoic anhydride, 2,2-difluoro-3-butenoic anhydride, 3-fluoro-2-butenoic anhydride, 4-fluoro-3-butenoic anhydride, 3,4-difluoro-3-butenoic anhydride, 3,3,4-trifluoro-3-butenoic anhydride, and analogs thereof.

[0109] R 9 and R 10 is an alkynyl group substituted with a halogen atom, examples of which include 3-fluoro-2-propynoic anhydride, 3-(4-fluorophenyl)-2-propynoic anhydride, 3-(2,3,4,5,6-pentafluorophenyl)-2-propynoic anhydride, 4-fluoro-2-butynoic anhydride, 4,4-difluoro-2-butynoic anhydride, 4,4,4-trifluoro-2-butynoic anhydride, and analogs thereof. R 9 and R 10 Examples of acid anhydrides in which is an aryl group substituted with a halogen atom include 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and the like, and analogs thereof. R 9 and R 10Examples of acid anhydrides having a substituent with a functional group such as an ester, a nitrile, a ketone, or an ether include methoxyformic anhydride, ethoxyformic anhydride, methyloxalic anhydride, ethyloxalic anhydride, 2-cyanoacetic anhydride, 2-oxopropionic anhydride, 3-oxobutanoic anhydride, 4-acetylbenzoic anhydride, methoxyacetic anhydride, 4-methoxybenzoic anhydride, and the like, and their analogs.

[0110] Next, R 9 and R 10 Specific examples of acid anhydrides having different groups are listed below. R 9 and R 10 Although all combinations of the above-mentioned examples and their analogues are conceivable, representative examples are given below. Examples of combinations of chain alkyl groups include acetic acid propionic anhydride, acetic acid butanoic anhydride, butanoic acid propionic anhydride, acetic acid 2-methylpropionic anhydride, Examples include: Examples of the combination of a chain alkyl group and a cyclic alkyl group include acetic acid cyclopentanoic anhydride, acetic acid cyclohexanoic anhydride, and cyclopentanoic acid propionic anhydride. Examples of the combination of a chain alkyl group and an alkenyl group include acetic acid acrylic anhydride, acetic acid 3-methylacrylic anhydride, acetic acid 3-butenoic anhydride, and acrylic acid propionic anhydride. Examples of combinations of a chain alkyl group and an alkynyl group include acetic acid propynoic anhydride, acetic acid 2-butynoic anhydride, acetic acid 3-butynoic anhydride, acetic acid 3-phenylpropynoic anhydride, and propionic acid propynoic anhydride. Examples of the combination of a chain alkyl group and an aryl group include acetic acid benzoic anhydride, acetic acid 4-methylbenzoic anhydride, acetic acid 1-naphthalenecarboxylic anhydride, and benzoic acid propionic anhydride. Examples of the combination of a chain alkyl group and a hydrocarbon group having a functional group include fluoroacetate. Examples include acetic anhydride, acetic trifluoroacetic anhydride, acetic 4-fluorobenzoic anhydride, fluoroacetic propionic anhydride, acetic alkyl oxalic anhydride, acetic 2-cyanoacetic anhydride, acetic 2-oxopropionic anhydride, acetic methoxyacetic anhydride, and methoxyacetic propionic anhydride.

[0111] Examples of combinations of cyclic alkyl groups include cyclopentanoic acid and cyclohexanoic acid anhydride. Examples of combinations of a cyclic alkyl group and an alkenyl group include acrylic acid cyclopentanoic anhydride, 3-methylacrylic acid cyclopentanoic anhydride, 3-butenoic acid cyclopentanoic anhydride, and acrylic acid cyclohexanoic anhydride. Examples of the combination of a cyclic alkyl group and an alkynyl group include propynoic cyclopentanoic anhydride, 2-butynoic cyclopentanoic anhydride, and propynoic cyclohexanoic anhydride. Examples of the combination of a cyclic alkyl group and an aryl group include benzoic acid cyclopentanoic acid anhydride, 4-methylbenzoic acid cyclopentanoic acid anhydride, and benzoic acid cyclohexanoic acid anhydride. Examples of combinations of a cyclic alkyl group and a hydrocarbon group having a functional group include cyclopentanoic fluoroacetic anhydride, cyclopentanoic trifluoroacetic anhydride, cyclopentanoic 2-cyanoacetic anhydride, cyclopentanoic methoxyacetic anhydride, and cyclohexanoic fluoroacetic anhydride.

[0112] Examples of combinations of alkenyl groups include acrylic acid 2-methylacrylic anhydride, acrylic acid 3-methylacrylic anhydride, acrylic acid 3-butenoic anhydride, and 2-methylacrylic acid 3-methylacrylic anhydride. Examples of a combination of an alkenyl group and an alkynyl group include acrylic acid propynoic anhydride, acrylic acid 2-butynoic anhydride, and 2-methylacrylic acid propynoic anhydride. Examples of combinations of an alkenyl group and an aryl group include acrylic acid benzoic acid anhydride, acrylic acid 4-methylbenzoic acid anhydride, and 2-methylacrylic acid benzoic acid anhydride. Examples of combinations of an alkenyl group and a hydrocarbon group having a functional group include acrylic fluoroacetic anhydride, acrylic trifluoroacetic anhydride, acrylic 2-cyanoacetic anhydride, acrylic methoxyacetic anhydride, and 2-methylacrylic fluoroacetic anhydride.

[0113] Examples of combinations of alkynyl groups include propynoic acid 2-butynoic acid anhydride, propynoic acid 3-butynoic acid anhydride, and 2-butynoic acid 3-butynoic acid anhydride. Examples of a combination of an alkynyl group and an aryl group include benzoic acid propynoic anhydride, 4-methylbenzoic acid propynoic anhydride, and benzoic acid 2-butynoic anhydride. Examples of the combination of an alkynyl group and a hydrocarbon group having a functional group include propynoic acid fluoroacetic anhydride, propynoic acid trifluoroacetic anhydride, propynoic acid 2-cyanoacetic anhydride, propynoic acid methoxyacetic anhydride, and 2-butynoic acid fluoroacetic anhydride.

[0114] Examples of combinations of aryl groups include benzoic acid 4-methylbenzoic acid anhydride, benzoic acid 1-naphthalenecarboxylic acid anhydride, and 4-methylbenzoic acid 1-naphthalenecarboxylic acid anhydride. Examples of the combination of an aryl group and a hydrocarbon group having a functional group include benzoic acid fluoroacetic anhydride, benzoic acid trifluoroacetic anhydride, benzoic acid 2-cyanoacetic anhydride, benzoic acid methoxyacetic anhydride, and 4-methylbenzoic acid fluoroacetic anhydride.

[0115] Examples of combinations of hydrocarbon groups having functional groups include fluoroacetic acid trifluoroacetic anhydride, fluoroacetic acid 2-cyanoacetic anhydride, fluoroacetic acid methoxyacetic anhydride, and trifluoroacetic acid 2-cyanoacetic anhydride. Among the acid anhydrides forming the chain structure, preferred are: Acetic anhydride, propionic anhydride, 2-methylpropionic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, etc., acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, 2,3-dimethylacrylic anhydride, 3,3-dimethylacrylic anhydride, 3-butenoic anhydride, 2-methyl-3-butenoic anhydride, propynoic anhydride, 2-butynoic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, trifluoroacetic anhydride, 3,3,3-trifluoropropionic anhydride, 2-(trifluoromethyl)acrylic anhydride, 2-(4-fluorophenyl)acrylic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, ethoxyformic anhydride, and more preferably, Acrylic anhydride, 2-methylacrylic anhydride, 3-methylacrylic anhydride, benzoic anhydride, 2-methylbenzoic anhydride, 4-methylbenzoic anhydride, 4-tert-butylbenzoic anhydride, 4-fluorobenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, methoxyformic anhydride, and ethoxyformic anhydride. These compounds are preferred from the viewpoint that they can appropriately form bonds with lithium oxalate salts to form coating films with excellent durability, thereby improving charge / discharge rate characteristics, input / output characteristics, and impedance characteristics, particularly after durability tests.

[0116] Next, R 9 and R 10 Specific examples of acid anhydrides in which the and bond to each other to form a cyclic structure are given below. First, R 9 and R 10Specific examples of acid anhydrides in which the above are bonded to each other to form a five-membered ring structure include succinic anhydride, 4-methylsuccinic anhydride, 4,4-dimethylsuccinic anhydride, 4,5-dimethylsuccinic anhydride, 4,4,5-trimethylsuccinic anhydride, 4,4,5,5-tetramethylsuccinic anhydride, 4-vinylsuccinic anhydride, 4,5-divinylsuccinic anhydride, 4-phenylsuccinic anhydride, 4,5-diphenylsuccinic anhydride, Examples of the phthalic anhydride include 4,4-diphenylsuccinic anhydride, citraconic anhydride, maleic anhydride, 4-methylmaleic anhydride, 4,5-dimethylmaleic anhydride, 4-phenylmaleic anhydride, 4,5-diphenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, 5,5-dimethylitaconic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, and the like, and their analogs. R 9 and R 10 Specific examples of acid anhydrides in which the and bond to each other to form a six-membered ring structure include cyclohexane-1,2-dicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, glutaric anhydride, and the like, and their analogs. R 9 and R 10 Specific examples of acid anhydrides in which the above are bonded to each other to form another cyclic structure include 5-norbornene-2,3-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride, pyromellitic acid anhydride, diglycolic acid anhydride, and the like, and their analogs. R 9 and R 10 and 5,6-trifluorosuccinic anhydride, and 4,4,5,5-trifluorosuccinic anhydride, 4,4,5,5-tetrafluorosuccinic anhydride, 4-fluoromaleic anhydride, 4,5-difluoromaleic anhydride, 5-fluoroitaconic anhydride, 5,5-difluoroitaconic anhydride, and analogs thereof.

[0117] The above R9 and R 10 Among the acid anhydrides in which Succinic anhydride, 4-methylsuccinic anhydride, 4-vinylsuccinic anhydride, 4-phenylsuccinic anhydride, citraconic anhydride, maleic anhydride, 4-methylmaleic anhydride, 4-phenylmaleic anhydride, itaconic anhydride, 5-methylitaconic anhydride, glutaric anhydride, phthalic anhydride, cyclohexane-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, 4-fluorosuccinic anhydride, 4-fluoromaleic anhydride, 5-fluoroitaconic anhydride, and more preferably, Examples of suitable compounds include succinic anhydride, 4-methylsuccinic anhydride, 4-vinylsuccinic anhydride, citraconic anhydride, cyclohexane-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic anhydride, and 4-fluorosuccinic anhydride. These compounds are preferred because they appropriately form bonds with lithium oxalate salts to form coatings with excellent durability, thereby improving the capacity retention rate, particularly after a durability test.

[0118] The molecular weight of the carboxylic acid anhydride is not limited and may be any value as long as it does not significantly impair the effects of the present invention, but is usually at least 90, preferably at least 95, and usually at most 300, preferably at most 200. When the molecular weight of the carboxylic acid anhydride is within the above range, an increase in the viscosity of the electrolyte can be suppressed, and the coating density can be optimized, thereby appropriately improving durability. The method for producing the carboxylic acid anhydride is not particularly limited, and any known method can be selected for production. The nonaqueous electrolyte solution of the present invention may contain any one of the above-described carboxylic acid anhydrides alone, or may contain two or more of them in any combination and ratio. The content of the carboxylic acid anhydride in the non-aqueous electrolyte solution of the present invention is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but it is desirable to include it in a concentration of usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, relative to the non-aqueous electrolyte solution of the present invention. When the content of the carboxylic acid anhydride is within the above range, the effect of improving cycle characteristics is easily exhibited, and the reactivity is suitable, so that the battery characteristics are easily improved.

[0119] <2-3-6. Overcharge prevention agent> In the nonaqueous electrolyte of the present invention, an overcharge inhibitor can be used to effectively prevent the nonaqueous electrolyte secondary battery from exploding or catching fire when the battery is overcharged or the like. Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, and 1,1,3-trimethyl-3-phenylindane; partially fluorinated compounds of the above aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, and p-cyclohexylfluorobenzene; fluorine-containing anisole compounds such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole; aromatic acetates such as 3-propylphenyl acetate, 2-ethylphenyl acetate, benzylphenyl acetate, methylphenyl acetate, benzyl acetate, and phenethylphenyl acetate; and aromatic carbonates such as diphenyl carbonate and methylphenyl carbonate. Among these, biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, diphenylcyclohexane, 1,1,3-trimethyl-3-phenylindane, 3-propylphenylacetate, 2-ethylphenylacetate, benzylphenylacetate, methylphenyl Preferred are phenyl acetate, benzyl acetate, phenethylphenyl acetate, diphenyl carbonate, and methylphenyl carbonate. These may be used alone or in combination of two or more. When two or more are used in combination, it is particularly preferred to use a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, or a combination of at least one selected from oxygen-free aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, and t-amylbenzene with at least one selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran, in terms of the balance between overcharge prevention properties and high-temperature storage properties. The content of the overcharge inhibitor is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present invention. The content of the overcharge inhibitor is usually 0.1 mass% or more, preferably 0.2 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, based on 100 mass% of the nonaqueous electrolyte solution, and is usually 5 mass% or less, preferably 4.8 mass% or less, and more preferably 4.5 mass% or less. Within this range, the effect of the overcharge inhibitor is easily exerted sufficiently, and battery properties such as high-temperature storage characteristics are improved.

[0120] <2-3-7. Other Auxiliaries> Other known auxiliary agents may be used in the nonaqueous electrolyte solution of the present invention. Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, and methoxyethyl-methyl carbonate; Methyl 2-propynyl oxalate, ethyl 2-propynyl oxalate, bis(2-propynyl)oxalate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, di(2-propynyl)glutarate, methyl 2-propynyl carbonate, ethyl 2-propynyl carbonate, bis(2-propynyl)carbonate, 2-butyne-1,4-diyl-dimethanesulfonate, 2-butyne-1,4-diyl-diethanesulfonate, 2-butyne-1,4-diyl-diformate, 2-butyne-1,4-diyl-diacetate, 2-butyne triple bond-containing compounds such as 2-propynyl-1,4-diyl-dipropionate, 4-hexadiyn-1,6-diyl-dimethanesulfonate, 2-propynyl-methanesulfonate, 1-methyl-2-propynyl-methanesulfonate, 1,1-dimethyl-2-propynyl-methanesulfonate, 2-propynyl-ethanesulfonate, 2-propynyl-vinylsulfonate, 2-propynyl-2-(diethoxyphosphoryl)acetate, 1-methyl-2-propynyl-2-(diethoxyphosphoryl)acetate, and 1,1-dimethyl-2-propynyl-2-(diethoxyphosphoryl)acetate; Spiro compounds such as 2,4,8,10-tetraoxaspiro[5.5]undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane; Sulfur-containing compounds such as ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolene, diphenyl sulfone, N,N-dimethylmethanesulfonamide, N,N-diethylmethanesulfonamide, trimethylsilyl methyl sulfate, trimethylsilyl ethyl sulfate, and 2-propynyl-trimethylsilyl sulfate; Isocyanate compounds such as 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl crotonate, 2-(2-isocyanatoethoxy)ethyl acrylate, 2-(2-isocyanatoethoxy)ethyl methacrylate, and 2-(2-isocyanatoethoxy)ethyl crotonate; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, and N-methylsuccinimide; Hydrocarbon compounds such as heptane, octane, nonane, decane, cycloheptane, etc.; fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride, pentafluorophenyl methanesulfonate, pentafluorophenyl trifluoromethanesulfonate, pentafluorophenyl acetate, pentafluorophenyl trifluoroacetate, and methyl pentafluorophenyl carbonate; Tris(trimethylsilyl) borate, tris(trimethoxysilyl) borate, tris(trimethylsilyl) phosphate, tris(trimethoxysilyl) phosphate, dimethoxyaluminoxytrimethoxysilane, diethoxyaluminoxytriethoxysilane, dipropoxyaluminoxytriethoxysilane, dibutoxyaluminoxytrimethoxysilane, dibutoxyaluminoxytriethoxysilane, titanium tetrakis(trimethylsiloxide), titanium tetrakis(triethylsiloxide), Silane compounds such as; Ester compounds such as 2-propynyl 2-(methanesulfonyloxy)propionate, 2-methyl 2-(methanesulfonyloxy)propionate, 2-ethyl 2-(methanesulfonyloxy)propionate, 2-propynyl methanesulfonyloxyacetate, 2-methyl methanesulfonyloxyacetate, and 2-ethyl methanesulfonyloxyacetate; Lithium salts such as lithium ethylmethyloxycarbonylphosphonate, lithium ethylethyloxycarbonylphosphonate, lithium ethyl-2-propynyloxycarbonylphosphonate, lithium ethyl-1-methyl-2-propynyloxycarbonylphosphonate, and lithium ethyl-1,1-dimethyl-2-propynyloxycarbonylphosphonate; These may be used alone or in combination of two or more. By adding these auxiliary agents, it is possible to improve the capacity retention characteristics and cycle characteristics after high-temperature storage. The content of the other auxiliary agents is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention. The content of the other auxiliary agents is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, based on 100% by mass of the non-aqueous electrolyte solution. Within this range, the effects of the other auxiliary agents are easily exerted, and battery characteristics such as high-load discharge characteristics are improved.

[0121] The nonaqueous electrolyte solution described above also includes that present inside an energy device such as a nonaqueous electrolyte secondary battery according to one embodiment of the present invention. Specifically, it includes a nonaqueous electrolyte solution in a nonaqueous electrolyte secondary battery obtained by separately synthesizing and substantially isolating components of the nonaqueous electrolyte solution, preparing a nonaqueous electrolyte solution from the resulting solution, and injecting the solution into a battery separately assembled by the method described below; a case in which components of the nonaqueous electrolyte solution of the present invention are individually placed in a battery and mixed in the nonaqueous electrolyte secondary battery to obtain the same composition as the nonaqueous electrolyte solution of the present invention; and a case in which compounds constituting the nonaqueous electrolyte solution of the present invention are generated in the nonaqueous electrolyte secondary battery to obtain the same composition as the nonaqueous electrolyte solution of the present invention.

[0122] <2-4. Method for producing non-aqueous electrolyte> The nonaqueous electrolytic solution of the present invention can be prepared by dissolving the electrolyte, the compound belonging to group (A) and the fluorosulfonate (B) in a predetermined content ratio in the nonaqueous solvent, and, if necessary, the above-mentioned "auxiliary agent" or the like. When preparing a non-aqueous electrolyte solution, it is preferable to dehydrate each raw material of the non-aqueous electrolyte solution, i.e., the electrolyte such as a lithium salt, the compound belonging to group (A) and the fluorosulfonate salt (B), the non-aqueous solvent, the auxiliary agent, etc. The degree of dehydration is usually 50 ppm or less, preferably 30 ppm or less. By removing the water content from the non-aqueous electrolyte solution, the electrolysis of water, the reaction between water and lithium metal, the hydrolysis of lithium salts, etc. are less likely to occur. There are no particular limitations on the means for dehydration, but examples include When the object to be dehydrated is a liquid such as a non-aqueous solvent, a desiccant such as a molecular sieve can be used. When the object to be dehydrated is a solid such as an electrolyte, it can be dried by heating below the temperature at which decomposition occurs.

[0123] <3. Energy devices using non-aqueous electrolytes> An energy device using the nonaqueous electrolyte solution of the present invention comprises a plurality of electrodes capable of absorbing or releasing metal ions and the nonaqueous electrolyte solution of the present invention described above. Specific examples of types of energy devices include primary batteries, secondary batteries, and metal ion capacitors such as lithium ion capacitors. Of these, primary batteries or secondary batteries are preferred, with secondary batteries being particularly preferred. It is also preferable that the nonaqueous electrolyte solution used in these energy devices is a so-called gel electrolyte, which is pseudo-solidified with a polymer or filler. The energy device will be described below.

[0124] <3-1. Nonaqueous electrolyte secondary battery> <3-1-1. Battery configuration> A nonaqueous electrolyte secondary battery according to one embodiment of the present invention (hereinafter also referred to as the nonaqueous secondary battery of the present invention) has the same configuration as conventionally known nonaqueous electrolyte secondary batteries, except for the nonaqueous electrolyte, and typically has a configuration in which a positive electrode and a negative electrode are stacked via a porous membrane (separator) impregnated with the nonaqueous electrolyte of the present invention, and these are housed in a case (exterior body). Therefore, the shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited, and may be any of a cylindrical type, a prismatic type, a laminate type, a coin type, a large type, etc.

[0125] <3-1-2. Non-aqueous electrolyte> As the nonaqueous electrolyte solution, the nonaqueous electrolyte solution of the present invention described above is used. Note that, within the scope of the present invention, it is also possible to mix the nonaqueous electrolyte solution of the present invention with other nonaqueous electrolyte solutions and use them.

[0126] <3-1-3. Negative electrode> The negative electrode active material used in the negative electrode is not particularly limited as long as it can electrochemically absorb and release metal ions. Specific examples include carbonaceous materials, metal compound materials, and lithium-containing metal composite oxide materials. These materials may be used alone or in any combination of two or more. Among these, carbonaceous materials and metal compound materials are preferred. Among metal compound materials, silicon-containing materials are preferred, and therefore carbonaceous materials and silicon-containing materials are particularly preferred as negative electrode active materials.

[0127] <3-1-3-1. Carbonaceous material> The carbonaceous material used as the negative electrode active material is not particularly limited, but is preferably selected from the following (a) to (d) because it provides a secondary battery with a good balance between initial irreversible capacity and high current density charge / discharge characteristics. (A) Natural graphite (a) Carbonaceous materials obtained by heat treating artificial carbonaceous substances and artificial graphite substances at least once in the range of 400°C to 3200°C (c) A carbonaceous material in which the negative electrode active material layer is made of at least two types of carbonaceous matter having different crystallinity and / or has an interface where the carbonaceous matter having different crystallinity is in contact with each other. (D) A carbonaceous material in which the negative electrode active material layer is made of at least two kinds of carbonaceous materials having different orientations and / or has an interface where the carbonaceous materials having different orientations are in contact with each other. The carbonaceous materials (a) to (d) may be used singly or in any combination of two or more in any ratio. Specific examples of the artificial carbonaceous material or artificial graphite material in (a) above include natural graphite, Coal coke, petroleum coke, coal pitch, petroleum pitch, and these pitches that have been oxidized; Needle coke, pitch coke, and partially graphitized carbon materials; Pyrolysis products of organic substances such as furnace black, acetylene black, and pitch-based carbon fiber; Carbonizable organic substances and their carbonized products; and Examples include charcoal solutions in which carbonizable organic materials are dissolved in low molecular weight organic solvents such as benzene, toluene, xylene, quinoline, and n-hexane. In addition, the above carbonaceous materials (a) to (d) are all well known, and their manufacturing methods are well known to those skilled in the art. In addition, these commercially available products can also be purchased.

[0128] <3-1-3-2. Metal compound materials> The metal compound material used as the negative electrode active material is not particularly limited as long as it is capable of absorbing and releasing lithium. Examples of such metal compounds include elemental metals or alloys that form alloys with lithium, as well as compounds such as oxides, carbides, nitrides, silicides, sulfides, and phosphides. Examples of such metal compounds include compounds containing metals such as Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, and Zn. Of these, elemental metals or alloys that form alloys with lithium are preferred, and materials containing metal or metalloid elements (i.e., excluding carbon; hereinafter, metals and metalloids are collectively referred to as "metals") from Group 13 or 14 of the Periodic Table are more preferred. Furthermore, elemental metals such as silicon (Si), tin (Sn), or lead (Pb) (hereinafter, these three elements may be referred to as "SSP metal elements"), alloys containing these atoms, or compounds of these metals (SSP metal elements) are particularly preferred. Silicon-containing compounds are particularly preferred. These may be used alone or in any combination of two or more in any ratio.

[0129] <3-1-3-3. Lithium-containing metal composite oxide materials> The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it is capable of absorbing and releasing lithium, but a lithium-containing composite metal oxide material containing titanium is preferred, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as "lithium titanium composite oxide") is particularly preferred. That is, when a lithium titanium composite oxide having a spinel structure is contained in a negative electrode active material for a lithium ion nonaqueous electrolyte secondary battery and used, the output resistance of the secondary battery is significantly reduced, which is particularly preferred. Also preferred are lithium-titanium composite oxides in which the lithium or titanium is substituted with another metal element, for example, at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. A lithium titanium composite oxide preferred as the negative electrode active material is represented by the following general formula (7). Li x Ti y M z O4(7) (In general formula (7), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. In addition, in general formula (7), it is preferable that 0.7≦x≦1.5, 1.5≦y≦2.3, and 0≦z≦1.6, because the structure is stable during doping and dedoping of lithium ions.)

[0130] <3-1-3-4. Negative electrode structure, properties, and preparation method> The negative electrode containing the above-mentioned active material, the electrode formation method, and the current collector can adopt known technical configurations, but it is desirable that one or more of the following items (i) to (vi) be satisfied simultaneously.

[0131] (i) Preparation of negative electrode The negative electrode may be produced by any known method as long as it does not significantly limit the effects of the present invention. For example, a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, and the like are added to the negative electrode active material to form a slurry of the negative electrode forming material, which is then applied to a current collector, dried, and pressed to form the negative electrode active material layer.

[0132] (ii) Current collector Any known current collector can be used to support the negative electrode active material. Examples of the negative electrode current collector include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel, but copper is particularly preferred from the standpoints of ease of processing and cost. When the current collector is made of a metal material, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punched metal, a foamed metal, etc. Among these, a metal thin film is preferred, a copper foil is more preferred, and a rolled copper foil produced by a rolling method and an electrolytic copper foil produced by an electrolytic method are even more preferred.

[0133] (iii) Thickness ratio of current collector to negative electrode active material layer The thickness ratio between the current collector and the negative electrode active material layer is not particularly limited, but the value of "(thickness of the negative electrode active material layer on one side immediately before the non-aqueous electrolyte solution injection step) / (thickness of the current collector)" is preferably 150 or less, more preferably 20 or less, and particularly preferably 10 or less, and is preferably 0.1 or more, more preferably 0.4 or more, and particularly preferably 1 or more. If the thickness ratio of the current collector to the negative electrode active material layer exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge of the secondary battery, whereas if it is below the above range, the volume ratio of the current collector to the negative electrode active material increases, which may reduce the capacity of the secondary battery.

[0134] (iv) Electrode density The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, and the density of the negative electrode active material present on the current collector is 1 g cm -3 More than 1.2 g cm is preferable. -3 More than 1.3 g cm is preferable. -3 More than 4g cm is more preferable.-3 Less than 3 g cm is preferable. -3 Less than 2.5 g cm is preferable. -3 Less than 1.7 g cm is more preferable. -3 The following is particularly preferred. When the density of the negative electrode active material present on the current collector is within the above range, the negative electrode active material particles are less likely to be destroyed, making it easier to prevent an increase in the initial irreversible capacity of the secondary battery and deterioration of high current density charge / discharge characteristics due to reduced permeability of the nonaqueous electrolyte solution near the current collector / negative electrode active material interface. Furthermore, conductivity between the negative electrode active materials can be ensured, and capacity per unit volume can be increased without increasing battery resistance.

[0135] (v) Binders, solvents, etc. The slurry for forming the negative electrode active material layer is usually prepared by adding a mixture of a solvent, a binder (binding agent), a thickener, etc. to the negative electrode active material. The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable to the non-aqueous electrolyte solution and the solvent used in producing the electrode. Specific examples thereof include resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose; Rubber-like polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluororubber, NBR (acrylonitrile-butadiene rubber), and ethylene-propylene rubber; Styrene-butadiene-styrene block copolymer or its hydrogenated products; Thermoplastic elastomeric polymers such as EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, or hydrogenated products thereof; Soft resinous polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymers; Polymer composition having ionic conductivity for alkali metal ions (especially lithium ions) These may be used alone or in any combination of two or more in any ratio. The solvent for forming the slurry is not particularly limited as long as it is capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as needed, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous solvent include water and alcohol, and examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N,N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphamide, dimethylsulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, and hexane. In particular, when an aqueous solvent is used, it is preferable to add a dispersant and the like together with the thickener, and form a slurry using a latex such as SBR. These solvents may be used alone or in any combination of two or more in any ratio.

[0136] The ratio of the binder to 100 parts by mass of the negative electrode active material is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.6 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less. When the ratio of the binder to the negative electrode active material is within the above range, the proportion of the binder that does not contribute to the battery capacity is not increased, so that a decrease in battery capacity is unlikely to occur. Furthermore, a decrease in the strength of the negative electrode is unlikely to occur. In particular, when the slurry that is the negative electrode forming material contains a rubber-like polymer typified by SBR as a main component, the ratio of the binder to 100 parts by mass of the negative electrode active material is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.6 parts by mass or more, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. Furthermore, when the slurry contains a fluorine-based polymer typified by polyvinylidene fluoride as a main component, the ratio of the binder to 100 parts by mass of the negative electrode active material is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less.

[0137] Thickeners are usually used to adjust the viscosity of the slurry. There are no particular limitations on the thickener, but specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in any combination and ratio of two or more. When a thickener is used, the ratio of the thickener to 100 parts by mass of the negative electrode active material is typically 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 0.6 parts by mass or more. Furthermore, the ratio is typically 5 parts by mass or less, preferably 3 parts by mass or less, and more preferably 2 parts by mass or less. When the ratio of the thickener to the negative electrode active material is within the above range, the coating properties of the slurry are improved. Furthermore, the ratio of the negative electrode active material in the negative electrode active material layer is also appropriate, making it less likely that problems such as a decrease in battery capacity or an increase in resistance between the negative electrode active materials will occur.

[0138] (vi) Area of negative plate The area of the negative electrode plate is not particularly limited, but it is preferable to make it slightly larger than the opposing positive electrode plate. It is preferable to design the negative electrode plate so that it does not protrude beyond the negative electrode plate. Furthermore, from the viewpoint of the cycle life of the secondary battery when repeatedly charged and discharged and suppressing deterioration due to high-temperature storage, it is preferable to make the area as close as possible to the positive electrode, since this increases the proportion of electrodes that work more uniformly and effectively, improving the characteristics. In particular, when the secondary battery is used with a large current, the design of the negative electrode plate area is important.

[0139] <3-1-4. Positive electrode> The positive electrode used in the non-aqueous electrolyte secondary battery of the present invention will be described below. <3-1-4-1. Positive electrode active material> The positive electrode active material used in the positive electrode will be described below.

[0140] (1) Composition The positive electrode active material is not particularly limited as long as it can electrochemically absorb and release metal ions, but for example, it is preferably a material capable of electrochemically absorbing and releasing lithium ions, and is preferably a material containing lithium and at least one transition metal. Specific examples include lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, lithium-containing transition metal silicate compounds, and lithium-containing transition metal borate compounds. The transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples of the composite oxide include lithium-cobalt composite oxides such as LiCoO2, lithium-nickel composite oxides such as LiNiO2, lithium-manganese composite oxides such as LiMnO2, LiMn2O4, and Li2MnO4, as well as lithium transition metal composite oxides in which a portion of the transition metal atoms that constitute the main components of these lithium transition metal composite oxides have been substituted with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. Specific examples of the substituted groups include LiNi 0.5 Mn 0.5 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.33 Co0.33 Mn 0.33 O2, LiMn2O4, LiMn 1.8 Al 0.2 O4, Li 1.1 Mn 1.9 Al 0.1 O4, LiMn 1.5 Ni 0.5 Examples include O4. Among these, a composite oxide containing lithium, nickel, and cobalt is more preferable, because a composite oxide containing cobalt and nickel can provide a large capacity when used at the same potential.

[0141] On the other hand, cobalt is a scarce and expensive metal, and since large batteries requiring high capacity for automotive applications, etc., require a large amount of active material, it is desirable to use manganese as the main component as a cheaper transition metal from a cost perspective. In other words, lithium-nickel-cobalt-manganese composite oxide is even more preferable. Among these, from the viewpoint of achieving a high balance between cost and capacity, lithium-nickel-cobalt-manganese composite oxide, which uses less cobalt and more nickel, is particularly preferable. For example, LiNi 0.5 Co 0.2 Mn 0.3 O2 and LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 O2 is a particularly preferred example. In addition, lithium manganese composite oxides having a spinel structure are also preferred in view of the stability of the compound and the procurement cost due to the ease of production. 1.8 Al 0.2 O4, Li 1.1 Mn 1.9 Al 0.1 O4, LiMn 1.5 Ni 0.5 O4 and the like can also be mentioned as preferred specific examples.

[0142] The transition metal of the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples of the phosphate compound include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, LiFeP2O7, cobalt phosphates such as LiCoPO4, manganese phosphates such as LiMnPO4, and lithium transition metal phosphate compounds in which a part of the transition metal atoms constituting the main component of these lithium transition metal phosphate compounds is replaced with Al, Ti, V, Cr, Mn, Fe, Co, Examples include those substituted with other metals such as Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. The transition metal in the lithium-containing transition metal silicate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples of the silicate compound include iron silicates such as LiFeSiO, cobalt silicates such as LiCoSiO, and lithium transition metal silicate compounds in which a portion of the transition metal atoms that constitute the main components of these compounds have been substituted with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, etc. The transition metal of the lithium-containing transition metal borate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc., and specific examples of the borate compound include iron borates such as LiFeBO3, cobalt borates such as LiCoBO3, and lithium transition metal borate compounds in which a portion of the transition metal atoms that constitute the main components has been substituted with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W, etc.

[0143] (2) Manufacturing method of positive electrode active material The method for producing the positive electrode active material is not particularly limited as long as it does not depart from the gist of the present invention, but several methods can be mentioned, and a general method for producing an inorganic compound can be used. In particular, various methods can be considered for producing spherical or oval-spherical active materials. One example is a method in which a transition metal raw material such as a transition metal nitrate or sulfate, and optionally raw materials of other elements, are dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring to produce and recover a spherical precursor, which is then dried as necessary, and a Li source such as LiOH, Li2CO3, or LiNO3 is added and the mixture is fired at a high temperature to obtain the active material. Another example of such a method is to dissolve or pulverize and disperse transition metal raw materials such as transition metal nitrates, sulfates, hydroxides, and oxides, and, if necessary, raw materials of other elements, in a solvent such as water, and then dry and mold them using a spray dryer or the like to form spherical or ellipsoidal precursors, to which a Li source such as LiOH, Li2CO3, or LiNO3 is added and calcined at a high temperature to obtain an active material. Yet another example of such a method is to dissolve or pulverize and disperse a transition metal raw material such as a transition metal nitrate, sulfate, hydroxide, or oxide, a Li source such as LiOH, Li2CO3, or LiNO3, and, if necessary, raw materials of other elements, in a solvent such as water, and then dry and mold the mixture using a spray dryer or the like to form a spherical or ellipsoidal precursor, which is then fired at a high temperature to obtain an active material.

[0144] <3-1-4-2. Positive electrode structure and manufacturing method> The structure of the positive electrode used in the present invention and the method for producing the same will be described below. (Positive electrode manufacturing method) The positive electrode is produced by forming a positive electrode active material layer containing positive electrode active material particles and a binder on a current collector. The positive electrode using the positive electrode active material can be produced by any known method. For example, the positive electrode active material and the binder, and optionally a conductive material and a thickener, are mixed in a dry state to form a sheet, which is then pressed onto the positive electrode current collector. Alternatively, these materials are dissolved or dispersed in a liquid medium to form a slurry, which is then applied to the positive electrode current collector and dried to form a positive electrode active material layer on the current collector, thereby obtaining a positive electrode. The content of the positive electrode active material in the positive electrode active material layer is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 99.9% by mass or less, more preferably 99% by mass or less. When the content of the positive electrode active material is within the above range, a sufficient electric capacity can be ensured. Furthermore, the strength of the positive electrode is also sufficient. In the present invention, the positive electrode active material powder may be used alone, or two or more types having different compositions or different powder properties may be used in any combination and ratio. When two or more types of active materials are used in combination, the composite oxide containing lithium and manganese is used as a powder component. As described above, cobalt and nickel are expensive metals with scarce resources, and large batteries requiring high capacity for automotive applications, etc., would require a large amount of active material, which is undesirable from the standpoint of cost, and therefore it is desirable to use manganese as a cheaper transition metal as the main component.

[0145] (Conductive material) Any known conductive material can be used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; and carbonaceous materials such as amorphous carbon such as needle coke. These materials may be used alone or in any combination and ratio of two or more. The content of the conductive material in the positive electrode active material layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 15% by mass or less. When the content is within the above range, sufficient conductivity can be ensured. Furthermore, a decrease in battery capacity can be easily prevented.

[0146] (binder) The binder used in producing the positive electrode active material layer is not particularly limited as long as it is a material that is stable to the non-aqueous electrolyte solution and the solvent used in producing the electrode. When the positive electrode is produced by the coating method, the binder is not particularly limited as long as it is a material that can be dissolved or dispersed in the liquid medium used in producing the electrode. Specific examples thereof include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, and nitrocellulose; Rubber-like polymers such as SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluororubber, isoprene rubber, butadiene rubber, and ethylene-propylene rubber; Thermoplastic elastomeric polymers such as styrene-butadiene-styrene block copolymers or their hydrogenated products, EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-ethylene copolymers, styrene-isoprene-styrene block copolymers or their hydrogenated products; Soft resinous polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; Fluoropolymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymers; Polymer composition having ionic conductivity for alkali metal ions (especially lithium ions) These substances may be used singly or in any combination of two or more in any ratio.

[0147] The content of the binder in the positive electrode active material layer is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, even more preferably 40% by mass or less, and particularly preferably 10% by mass or less. When the binder content is within the above range, the positive electrode active material can be sufficiently retained and the mechanical strength of the positive electrode can be ensured, resulting in good battery performance such as cycle characteristics. Furthermore, this also helps to avoid a decrease in battery capacity and conductivity.

[0148] (liquid medium) The liquid medium used to prepare the slurry for forming the positive electrode active material layer is not particularly limited in type, and either an aqueous solvent or an organic solvent may be used, as long as it is a solvent capable of dissolving or dispersing the positive electrode active material, the conductive material, the binder, and the thickener used as needed. Examples of the aqueous medium include water, a mixed medium of alcohol and water, etc. Examples of the organic medium include aliphatic hydrocarbons such as hexane; Aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; Heterocyclic compounds such as quinoline and pyridine; Ketones such as acetone, methyl ethyl ketone, and cyclohexanone; Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether and tetrahydrofuran (THF); Amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; Aprotic polar solvents such as hexamethylphosphatamide and dimethyl sulfoxide These may be used alone or in any combination of two or more in any ratio.

[0149] (thickener) When an aqueous medium is used as the liquid medium for forming the slurry, it is preferable to form the slurry using a thickener and a latex such as styrene butadiene rubber (SBR). The thickener is usually used to adjust the viscosity of the slurry. There are no limitations on the thickener as long as it does not significantly limit the effects of the present invention, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used alone or in any combination and ratio of two or more. When a thickener is used, the proportion of the thickener relative to the total mass of the positive electrode active material and the thickener is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.6% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less. Within the above range, the coating properties of the slurry are improved, and the proportion of the active material in the positive electrode active material layer is sufficient, making it easier to avoid problems such as a decrease in the capacity of the secondary battery and an increase in resistance between the positive electrode active materials.

[0150] (Consolidation) The positive electrode active material layer obtained by applying the above slurry to the current collector and drying it is preferably compacted using a hand press, roller press, or the like to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is 1 g cm -3 More than 1.5g cm is preferable. -3 More than 2g cm is more preferable. -3 Above 4g cm is particularly preferable. -3 Less than 3.9 g cm is preferred -3 Less than 3.8 g cm is more preferable. -3 The following are particularly preferred: When the density of the positive electrode active material layer is within the above range, the permeability of the nonaqueous electrolyte solution near the current collector / active material interface is not reduced, and the charge / discharge characteristics of the secondary battery, particularly at high current densities, are improved. Furthermore, the conductivity between the active materials is less likely to decrease, and the battery resistance is less likely to increase.

[0151] (current collector) The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbonaceous materials such as carbon cloth and carbon paper. Among these, metal materials, especially aluminum, are preferred. The shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punched metal, or a foamed metal, for a metal material, or a carbon plate, a carbon thin film, or a carbon cylinder, for a carbonaceous material. Of these, a metal thin film is preferred. The thin film may be formed into a mesh as appropriate.

[0152] The thickness of the current collector is optional, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, and is preferably 1 mm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. When the thickness of the current collector is within the above range, the strength required as a current collector can be sufficiently ensured. Furthermore, handling is also improved. The thickness ratio of the current collector to the positive electrode active material layer is not particularly limited, but (thickness of the active material layer on one side immediately before the nonaqueous electrolyte is poured) / (thickness of the current collector) is preferably 150 or less, more preferably 20 or less, particularly preferably 10 or less, and also preferably 0.1 or more, more preferably 0.4 or more, particularly preferably 1 or more. When the thickness ratio of the current collector to the positive electrode active material layer is within the above range, the current collector is less likely to generate heat due to Joule heat during high current density charge / discharge of the secondary battery. Furthermore, the volume ratio of the current collector to the positive electrode active material is less likely to increase, preventing a decrease in battery capacity.

[0153] (electrode area) From the viewpoint of enhancing high output and stability at high temperatures, the area of the positive electrode active material layer is preferably larger than the outer surface area of the battery outer case. Specifically, the total electrode area of the positive electrode relative to the surface area of the outer case of the nonaqueous electrolyte secondary battery is preferably 20 times or more, more preferably 40 times or more, in terms of area ratio. In the case of a rectangular outer case with a bottom, the outer surface area refers to the total area calculated from the length, width, and thickness of the case portion filled with the power generating elements, excluding the terminal protrusions. In the case of a cylindrical outer case with a bottom, the outer surface area refers to the geometric surface area of the case portion filled with the power generating elements, excluding the terminal protrusions, approximated as a cylinder. The total electrode area of the positive electrode refers to the geometric surface area of the positive electrode composite layer facing the composite layer containing the negative electrode active material. In a structure in which positive electrode composite layers are formed on both sides via a current collector foil, the total area refers to the sum of the areas calculated separately for each side.

[0154] (discharge capacity) When the nonaqueous electrolyte of the present invention is used, the electric capacity of the battery element housed in one battery exterior of the nonaqueous electrolyte secondary battery (the electric capacity when the battery is discharged from a fully charged state to a discharged state) is preferably 1 ampere-hour (Ah) or more, since this significantly improves the low-temperature discharge characteristics. Therefore, the positive electrode plate is designed so that the discharge capacity at full charge is preferably 3 Ah (ampere-hour), more preferably 4 Ah or more, and preferably 20 Ah or less, more preferably 10 Ah or less. Within the above range, the voltage drop due to electrode reaction resistance during large current draw is prevented from becoming too large, preventing a deterioration in power efficiency. Furthermore, the temperature distribution due to internal heat generation during pulse charge / discharge is prevented from becoming too large, avoiding phenomena such as poor durability during repeated charge / discharge and poor heat dissipation efficiency in response to sudden heat generation during abnormalities such as overcharging or internal short circuit.

[0155] (Positive electrode thickness) The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity, high output, and high rate characteristics, the thickness of the positive electrode active material layer minus the thickness of the current collector is preferably 10 μm or more, more preferably 20 μm or more, and is preferably 200 μm or less, more preferably 150 μm or less, on one side of the current collector.

[0156] <3-1-5. Separator> In the nonaqueous electrolyte secondary battery of the present invention, a separator is usually interposed between the positive electrode and the negative electrode to prevent short-circuiting. In this case, the nonaqueous electrolyte of the present invention is usually impregnated into the separator before use. There are no particular limitations on the material or shape of the separator, and any known material can be used as long as it does not significantly impair the effects of the present invention. It is preferable to use a material formed from a stable material such as resin, glass fiber, or inorganic material, and to use a porous sheet or nonwoven fabric having excellent liquid retention properties. Examples of materials that can be used for the resin and glass fiber separator include polyolefins such as polyethylene and polypropylene, aramid resins, polytetrafluoroethylene, polyethersulfone, and glass filters. Among these, glass filters and polyolefins are preferred, and polyolefins are more preferred. These materials may be used alone or in any combination and ratio of two or more.

[0157] The thickness of the separator is arbitrary, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. When the separator thickness is within the above range, the insulating properties and mechanical strength are excellent. Furthermore, deterioration of battery performance such as rate characteristics can be prevented, and a decrease in the energy density of the nonaqueous electrolyte secondary battery as a whole can also be prevented. Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is optional, but is preferably 20% or more, more preferably 35% or more, even more preferably 45% or more, and is preferably 90% or less, more preferably 85% or less, even more preferably 75% or less. When the porosity is within the above range, the membrane resistance does not become too large, and deterioration of the rate characteristics of the secondary battery can be suppressed. Furthermore, the mechanical strength of the separator is moderate, and deterioration of the insulating properties can be suppressed. The average pore size of the separator can be any value, but is preferably 0.5 μm or less, more preferably 0.2 μm or less, and preferably 0.05 μm or more. When the average pore size is within the above range, short circuits are less likely to occur. Furthermore, the membrane resistance is not too high, and a decrease in the rate characteristics of the secondary battery can be prevented. On the other hand, inorganic materials include, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate, and these are used in particulate or fibrous form. The separator may be in the form of a thin film such as a nonwoven fabric, a woven fabric, or a microporous film. A thin film separator preferably has a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm. In addition to the above-mentioned independent thin film, a separator may be used in which a composite porous layer containing inorganic particles is formed on the surface of the positive electrode and / or negative electrode using a resin binder. For example, a porous layer may be formed on both sides of the positive electrode using alumina particles with a 90% particle size of less than 1 μm and a fluororesin as a binder.

[0158] <3-1-6.Battery design> (electrode group) The electrode group may have either a laminated structure formed by sandwiching the positive and negative electrode plates with the separator therebetween, or a structure formed by spirally winding the positive and negative electrode plates with the separator therebetween. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupancy rate) is preferably 40% or more, more preferably 50% or more, and is preferably 95% or less, more preferably 90% or less. When the electrode group occupancy rate is within the above range, the battery capacity is less likely to decrease. In addition, since an appropriate amount of void space can be secured, it is possible to prevent the battery from becoming hot and causing components to expand or the vapor pressure of the nonaqueous electrolyte components to increase, resulting in an increase in internal pressure and a decrease in various characteristics of the secondary battery, such as the charge / discharge cycle performance and high-temperature storage characteristics, as well as the activation of a gas release valve that releases internal pressure.

[0159] (current collection structure) The current collecting structure is not particularly limited, but the improvement of discharge characteristics by the non-aqueous electrolyte of the present invention is In order to achieve the above more effectively, it is preferable to use a structure that reduces the resistance of wiring portions and junction portions. When the internal resistance is reduced in this way, the effect of using the nonaqueous electrolyte solution of the present invention is particularly well exhibited. When the electrode group has the aforementioned laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to a terminal is preferably used. When the area of a single electrode is large, the internal resistance increases, so it is also preferable to provide multiple terminals within the electrode to reduce the resistance. When the electrode group has the aforementioned wound structure, the internal resistance can be reduced by providing multiple lead structures on each of the positive and negative electrodes and bundling them to a terminal.

[0160] (protective element) Examples of protective elements include PTC (Positive Temperature Coefficient) thermistors, whose resistance increases when abnormal heat is generated or excessive current flows, thermal fuses, and valves (current cutoff valves) that cut off the current flowing in the circuit due to a sudden rise in the battery's internal pressure or temperature when abnormal heat is generated. It is preferable to select protective elements that will not operate under normal high-current use, and it is even more preferable to design a battery that will not experience abnormal heat generation or thermal runaway even without protective elements.

[0161] (exterior body) The nonaqueous electrolyte secondary battery of the present invention is generally constructed by housing the above-mentioned nonaqueous electrolyte, negative electrode, positive electrode, separator, etc. in an exterior body (exterior case). There are no limitations on this exterior body, and any known exterior body can be used as long as it does not significantly impair the effects of the present invention. The material of the outer case is not particularly limited as long as it is stable against the non-aqueous electrolyte solution used. Specifically, metals such as nickel-plated steel sheet, stainless steel, aluminum or aluminum alloy, magnesium alloy, nickel, titanium, etc., or a laminate film of resin and aluminum foil (laminate film) are used. From the viewpoint of weight reduction, metals such as aluminum or aluminum alloy and laminate film are preferably used. Examples of exterior cases using the above metals include those in which the metals are welded together to form a sealed, airtight structure by laser welding, resistance welding, or ultrasonic welding, or those in which the metals are used via a resin gasket to form a crimped structure. Examples of exterior cases using the above laminate film include those in which the resin layers are heat-sealed to form a sealed, airtight structure. In order to improve sealing properties, a resin different from the resin used in the laminate film may be interposed between the resin layers. In particular, when the resin layer is heat-sealed via a current collecting terminal to form a sealed structure, the metal and the resin are joined, so a resin having a polar group or a modified resin into which a polar group has been introduced is preferably used as the interposed resin. The shape of the exterior case is also arbitrary, and may be, for example, cylindrical, rectangular, laminated, coin-shaped, large, or the like.

[0162] <3-2.Non-aqueous electrolyte primary battery> A nonaqueous electrolyte primary battery according to one embodiment of the present invention uses, for example, a material capable of absorbing metal ions in the positive electrode and a material capable of releasing metal ions in the negative electrode. The positive electrode material is preferably a transition metal oxide such as graphite fluoride or manganese dioxide. The negative electrode material is preferably a metal element such as zinc or lithium. The nonaqueous electrolyte used is the nonaqueous electrolyte of the present invention described above.

[0163] <3-3. Metal ion capacitor> A metal ion capacitor according to one embodiment of the present invention uses, for example, a material capable of forming an electric double layer for the positive electrode and a material capable of absorbing and releasing metal ions for the negative electrode. Activated carbon is preferred as the positive electrode material. A carbonaceous material is preferred as the negative electrode material. The nonaqueous electrolyte solution used is the nonaqueous electrolyte solution of the present invention described above.

[0164] <3-4. Electric double layer capacitor> In an electric double layer capacitor according to one embodiment of the present invention, for example, a material capable of forming an electric double layer is used for the electrodes. Activated carbon is a preferred electrode material. The nonaqueous electrolyte solution used is the nonaqueous electrolyte solution of the present invention. [Example]

[0165] The present invention will be explained in more detail below by way of examples and reference examples, but the present invention is not limited to these examples as long as it does not depart from the gist of the invention.

[0166] Example 1 [Preparation of negative electrode] To 98 parts by mass of the carbonaceous material, 1 part by mass of an aqueous dispersion of sodium carboxymethylcellulose (concentration of sodium carboxymethylcellulose: 1% by mass) and 1 part by mass of an aqueous dispersion of styrene-butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) were added as thickeners and binders, and the mixture was mixed in a disperser to form a slurry. The resulting slurry was applied to a 10 μm thick copper foil, dried, and rolled in a press. The resulting foil was cut into shapes with an active material layer size of 30 mm wide and 40 mm long, and an uncoated portion of 5 mm wide and 9 mm long to form a negative electrode.

[0167] [Preparation of positive electrode] LiNi as the positive electrode active material 0.6 Mn 0.2 Co 0.2 94% by mass of O2, 3% by mass of acetylene black as a conductive material, and 3% by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in N-methylpyrrolidone solvent to form a slurry. The resulting slurry was applied to one side of a 15 μm thick aluminum foil that had previously been coated with a conductive additive, dried, and roll-pressed in a press. The resultant was cut into a shape with an active material layer size of 30 mm wide and 40 mm long, and an uncoated area of 5 mm wide and 9 mm long to form a positive electrode.

[0168] [Preparation of non-aqueous electrolyte] In a dry argon atmosphere, 4.99 mass % of dried (FSO2)2NLi (hereinafter referred to as lithium bisfluorosulfonylimide), 0.01 mass % of FSO3Li, and 8.8 mass % of LiPF6 were dissolved in a mixture (volume ratio 30:30:40) of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), to prepare a nonaqueous electrolyte solution of Example 1.

[0169] [Manufacturing of non-aqueous electrolyte secondary batteries] The positive electrode, negative electrode, and polyethylene separator were stacked in this order to prepare a battery element. This battery element was inserted into a bag made of a laminate film of aluminum (40 μm thick) coated on both sides with a resin layer so that the positive and negative electrode terminals of the battery element protruded from the bag. The electrolyte solution was then poured into the bag, which was then vacuum-sealed to prepare a sheet-like nonaqueous electrolyte secondary battery of Example 1 that was fully charged at 4.3 V.

[0170] [Evaluation of initial discharge capacity] The nonaqueous electrolyte secondary battery was sandwiched between glass plates to enhance adhesion between the electrodes, and charged to 4.3 V at a constant current equivalent to 0.2 C at 25 ° C., then discharged to 2.8 V at a constant current of 0.2 C. This was repeated for two cycles to stabilize the battery. In the third cycle, the battery was charged to 4.3 V at a constant current of 0.2 C, then charged at a constant voltage of 4.3 V until the current value reached 0.05 C, and discharged to 2.8 V at a constant current of 0.2 C. Then, in the fourth cycle, the battery was charged to 4.3 V at a constant current of 0.2 C, then charged at a constant voltage of 4.3 V until the current value reached 0.05 C, and discharged to 2.8 V at a constant current of 0.2 C to determine the initial discharge capacity.

[0171] [Evaluation of output characteristics] After evaluation of the initial discharge capacity, the batteries were charged at 25°C at a constant current of 0.2 C to half the initial discharge capacity. These were then discharged at 0.5 C, 1.0 C, 1.5 C, 2.0 C, and 2.5 C at 25°C, and the voltage was measured after 10 seconds. The current value at 2.8 V was determined from the current-voltage line, and 2.8 × (current value at 2.8 V) was used as the output (W). The results are shown in Table 1. In Table 1, the output value of Example 1 is listed as a relative output when the output of Comparative Example 1 described below is set to 100. The same applies hereinafter.

[0172] [Input characteristic evaluation] After evaluation of the initial discharge capacity, the batteries were charged at 25°C at a constant current of 0.2 C to half the initial discharge capacity. These were then charged at 25°C at 0.5 C, 1.0 C, 1.5 C, 2.0 C, and 2.5 C, and the voltage was measured after 10 seconds. The current value at 4.3 V was determined from the current-voltage curve, and 4.3 × (current value at 4.3 V) was defined as the input (W). The results are shown in Table 1. In Table 1, the input value of Example 1 is listed as a relative input when the input value of Comparative Example 1 described below is set to 100. The same applies below.

[0173] Example 2 A sheet-shaped nonaqueous electrolyte secondary battery of Example 2 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 4.9 mass % and 0.1 mass %, respectively. The results are shown in Table 1. [Evaluation of cycle characteristics] After evaluation of the initial discharge capacity, the battery was charged at 25°C at a constant current of 1 C to 4.3 V, and then discharged at a constant current of 0.2 C to 2.8 V. This constituted one cycle, and 100 cycles were performed, and the 25°C cycle capacity retention rate was calculated by dividing the discharge capacity at 100 cycles by the initial discharge capacity x 100. The results are shown in Table 1. In Table 1, the 25°C cycle capacity retention rate value of Example 2 is shown as a relative value when the input voltage of Comparative Example 1 described below is taken as 100. The same applies hereinafter.

[0174] Example 3 A sheet-shaped nonaqueous electrolyte secondary battery of Example 3 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 4.5 mass % and 0.5 mass %, respectively. The results are shown in Table 1.

[0175] Example 4 A sheet-shaped nonaqueous electrolyte secondary battery of Example 4 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 4.0 mass % and 1.0 mass %, respectively. The results are shown in Table 1.

[0176] Example 5 A sheet-shaped nonaqueous electrolyte secondary battery of Example 5 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSOLi were dissolved to concentrations of 3.0 mass % and 2.0 mass %, respectively. The results are shown in Table 1.

[0177] Example 6 A sheet-shaped nonaqueous electrolyte secondary battery of Example 6 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 6.0 mass % and 0.5 mass %, respectively. The results are shown in Table 1.

[0178] (Comparative Example 1) FSO3Li was not dissolved, and lithium bisfluorosulfonylimide was 5.0 mass%. A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 1 was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0179] (Comparative Example 2) A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 2 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 2.0 mass % and 3.0 mass %, respectively. The results are shown in Table 1.

[0180] (Comparative Example 3) A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 3 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were dissolved to concentrations of 1.0 mass % and 4.0 mass %, respectively. The results are shown in Table 1.

[0181] Comparative Example 4 An attempt was made to mix 4.0% by mass of lithium bisfluorosulfonylimide and 1.0% by mass of lithium methylsulfate and dissolve the mixture in a non-aqueous electrolyte solution, but the lithium methylsulfate did not dissolve, and a sheet-shaped non-aqueous electrolyte secondary battery could not be produced, so the evaluation was discontinued.

[0182] (Comparative Example 5) A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 5 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide was dissolved to a concentration of 14.4 mass % and FSO3Li to a concentration of 0.5 mass %, and no LiPF6 was dissolved. The results are shown in Table 1.

[0183] [Table 1]

[0184] As is clear from Table 1, Examples 1 to 6 are superior in input / output characteristics and cycle capacity retention rate to Comparative Examples 1 to 3. That is, when the ratio of the mass content of fluorosulfonate (B) to the mass content of lithium bisfluorosulfonylimide, which is a compound belonging to group (A), is 1 or less, good effects are exhibited in input / output characteristics and cycle capacity retention rate. It is also clear that Examples 1 to 6 exhibit good relative output and relative input compared to Comparative Example 5, in which the content by mass of lithium bisfluorosulfonylimide, a compound belonging to group (A), exceeds 8 mass %. In addition, when 1.0 mass % of lithium methyl sulfate, which has a structure relatively similar to that of fluorosulfonate (B), was used, lithium methyl sulfate did not dissolve, and a uniform non-aqueous electrolyte solution could not be prepared. From this, it can be seen that even if a compound has a structure similar to that of fluorosulfonate (B), the use of fluorosulfonate (B) exerts an effect as described in this specification. It is clear that this is essential.

[0185] Example 7 A sheet-shaped nonaqueous electrolyte secondary battery of Example 7 was fabricated and evaluated in the same manner as in Example 1, except that 1.25 mass% of 1,2-ethylene sulfate, 0.75 mass% of FSO3Li, and 13.6 mass% of LiPF6 were dissolved, and lithium bisfluorosulfonylimide was not dissolved. The results are shown in Table 2. Table 2 lists values relative to the value of Comparative Example 6 described below, which is set to 100.

[0186] (Comparative Example 6) A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 6 was fabricated and evaluated in the same manner as in Example 1, except that 2 mass % of 1,2-ethylene sulfate and 13.6 mass % of LiPF were dissolved, and lithium bisfluorosulfonylimide and FSO3Li were not dissolved. The results are shown in Table 2.

[0187] [Table 2]

[0188] As is clear from Table 2, Example 7 is superior to Comparative Example 6 in terms of input / output characteristics and cycle capacity retention. That is, when the ratio of the mass content of fluorosulfonate (B) to the mass content of 1,2-ethylene sulfate, which is a compound belonging to group (A), is 1 or less, favorable effects are exhibited in terms of input / output characteristics and cycle capacity retention.

[0189] Example 8 1,3-propene sultone 1.25 mass%, FSO3Li 0.75 mass%, and L A sheet-shaped nonaqueous electrolyte secondary battery of Example 8 was fabricated and evaluated in the same manner as in Example 1, except that iPF6 was dissolved to a concentration of 13.6 mass % and lithium bisfluorosulfonylimide was not dissolved. The results are shown in Table 3. Table 3 lists values relative to the value of Comparative Example 7 described below, which is set to 100.

[0190] (Comparative Example 7) 1,3-propene sultone was dissolved to a concentration of 2 mass% and LiPF6 to a concentration of 13.6 mass%. A sheet-shaped nonaqueous electrolyte secondary battery of Comparative Example 7 was fabricated and evaluated in the same manner as in Example 1, except that lithium bisfluorosulfonylimide and FSO3Li were not dissolved in the electrolyte. The results are shown in Table 3.

[0191] [Table 3]

[0192] As is clear from Table 3, Example 8 is superior to Comparative Example 7 in input / output characteristics and cycle capacity retention rate. When the ratio of the mass content of the fluorosulfonate (B) to the mass content of the sultone is 1 or less, favorable effects are exhibited on the input / output characteristics and cycle capacity retention rate. [Industrial Applicability]

[0193] The nonaqueous electrolyte of the present invention is useful for improving the cycle capacity retention rate of nonaqueous electrolyte secondary batteries during endurance, such as during cycle operation or high-temperature storage, as well as post-cycle input / output characteristics (input / output retention rate), and battery swelling. Therefore, the nonaqueous electrolyte of the present invention and energy devices, such as nonaqueous electrolyte secondary batteries, can be used in a variety of well-known applications. Specific examples include laptops, pen-input PCs, mobile PCs, e-book players, mobile phones, mobile fax machines, mobile copiers, mobile printers, headphone stereos, video camcorders, LCD TVs, handheld vacuum cleaners, portable CD players, minidiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting equipment, toys, game consoles, watches, power tools, flash devices, cameras, home backup power supplies, business backup power supplies, load-leveling power supplies, and natural energy storage power supplies.

Claims

1. 1,2-ethylene sulfate (A), The following formula (2): (FSO ３ ) ｘ M (2) [In formula (2), M is a metal atom, and x is the valence of the metal atom M and is an integer of 1 or more] A non-aqueous electrolyte solution containing a fluorosulfonate (B) represented by the ratio of the mass content of the fluorosulfonate (B) to the mass content of the compound belonging to (A) in the nonaqueous electrolyte solution is 0.250 or more and 1 or less, A nonaqueous electrolyte solution in which the content of the compound belonging to (A) in the nonaqueous electrolyte solution is 0.01 mass % or more and 8 mass % or less (excluding those containing a compound having a structure represented by the following formula (8)). 【Chemical 1】 (In formula (8), R １ ~R ３ is an organic group having 1 to 20 carbon atoms which may have a substituent. 。）

2. The non-aqueous electrolyte solution according to claim 1, wherein the content of the fluorosulfonate (B) in the non-aqueous electrolyte solution is 2 mass% or less.

3. The fluorosulfonic acid salt (B) is FSO ３ The nonaqueous electrolyte solution according to claim 1 or 2, which contains Li.

4. The non-aqueous electrolyte solution is LiPF ６ The non-aqueous electrolyte solution according to claim 1 , comprising:

5. An energy device comprising: a plurality of electrodes capable of absorbing and releasing metal ions; and the nonaqueous electrolyte solution according to claim 1 .

6. 6. The energy device according to claim 5, wherein the plurality of electrodes capable of absorbing and desorbing metal ions are a positive electrode and a negative electrode, and the negative electrode contains a carbonaceous material or a material containing silicon.

7. 7. The energy device according to claim 5, wherein the plurality of electrodes capable of absorbing and desorbing metal ions are a positive electrode and a negative electrode, and the positive electrode contains a transition metal oxide.

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