Non-aqueous electrolyte and non-aqueous electrolyte battery

Abstract

Provided is a non-aqueous electrolyte for a non-aqueous electrolyte battery, the non-aqueous electrolyte comprising a positive electrode and a negative electrode which are capable of absorbing and releasing metal ions. The non-aqueous electrolyte is characterized by containing at least one compound selected from among a compound represented by general formula (A), a compound represented by general formula (B), and a compound represented by general formula (C), together with alkali metal salts and a non-aqueous solvent, and further containing a compound represented by general formula (α).

Description

[Technical Field]

[0001] The present invention relates to a nonaqueous electrolyte and a nonaqueous electrolyte battery, and more particularly to a nonaqueous electrolyte containing a specific amount of a specific compound, and a nonaqueous electrolyte battery using this nonaqueous electrolyte. [Background technology]

[0002] BACKGROUND ART Non-aqueous electrolyte batteries such as lithium secondary batteries have been put to practical use in a wide range of applications, such as power sources for so-called small consumer devices such as mobile phones such as smartphones and laptop computers, and on-board power sources for driving electric vehicles and the like.

[0003] As a means for improving the battery characteristics of non-aqueous electrolyte batteries, many studies have been conducted in the fields of active materials for positive and negative electrodes and additives for non-aqueous electrolytes.

[0004] For example, Patent Document 1 discloses a study on improving the cycle capacity retention rate and suppressing an increase in the internal resistance of the battery by adding a specific unsaturated silane compound or unsaturated siloxane compound to a non-aqueous electrolyte solution. Patent Document 2 discloses a study to improve the storage stability of a silyl group-containing compound by adding a trialkylsilyl compound of a protonic acid, sulfonic acid, or carboxylic acid having a phosphorus atom and / or a boron atom, and a basic compound or a specific silicon compound to a non-aqueous electrolyte solution, and further to improve the 4.9 V high voltage cycle capacity retention rate and the amount of gas generated during battery operation. Patent Document 3 discloses a study on suppressing storage gas generation in a nonaqueous electrolyte secondary battery that uses a lithium-nickel-manganese-cobalt composite oxide with a high Ni content as the positive electrode by adding a specific unsaturated silane compound to the nonaqueous electrolyte. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-134169 [Patent Document 2] International Publication No. 2015 / 098471 [Patent Document 3] International Publication No. 2019 / 059365 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the trend toward higher-capacity lithium batteries has accelerated for use as power sources for electric vehicles and mobile phones such as smartphones, and the proportion of voids within the battery has become smaller than before. Therefore, the large amount of gas generation during initial conditioning and in high-temperature environments is a fatal drawback. By using the electrolyte solutions described in Patent Documents 1 to 3, the effects disclosed in the documents can be obtained, but there is room for improvement in initial conditioning and suppression of gas generation in high-temperature environments.

[0007] An object of the present invention is to provide a nonaqueous electrolyte solution that can suppress the amount of gas generation during initial conditioning of a nonaqueous electrolyte battery. Another object of the present invention is to provide a nonaqueous electrolyte battery in which the amount of gas generation during initial conditioning is suppressed. Another object of the present invention is to provide a nonaqueous electrolyte solution that can suppress the amount of gas generation during high-temperature storage of a nonaqueous electrolyte battery, and to provide a nonaqueous electrolyte battery in which the amount of gas generation during high-temperature storage is suppressed. [Means for solving the problem]

[0008] As a result of intensive research to solve the above problems, the present inventors have come up with the idea that the amount of gas generated during initial conditioning and high-temperature storage can be suppressed by using a nonaqueous electrolyte solution containing a compound represented by general formula (A), a compound represented by general formula (B), or a compound represented by general formula (C), and a compound represented by general formula (α), and have completed the present invention.

[0009] [1] A non-aqueous electrolyte solution for a non-aqueous electrolyte battery having a positive electrode and a negative electrode capable of absorbing and releasing metal ions, the non-aqueous electrolyte solution containing, together with an alkali metal salt and a non-aqueous solvent, at least one compound selected from the group consisting of a compound represented by general formula (A), a compound represented by general formula (B), and a compound represented by general formula (C), and further containing a compound represented by general formula (α). [ka] (In formula (A), R 1 ~R 6 each independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an alkoxy group having 1 to 12 carbon atoms which may have a substituent, and n represents an integer of 1 to 5. [ka] (In formula (B), R 7 ~R 8 each independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an alkoxy group having 1 to 12 carbon atoms which may have a substituent, and k represents an integer of 3 to 6. [ka] (In formula (C), R 1a ~R 3a each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a hetero atom, or a trialkylsilyl group which may have a substituent. 1a ~R 3a may be bonded to each other to form a ring. [ka] (In formula (α), R 9 ~R 11each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms; and Y represents an alkenyl group or alkynyl group having 2 to 10 carbon atoms which may have a substituent. [2] The total content of at least one compound selected from the compound represented by the general formula (A), the compound represented by the general formula (B), and the compound represented by the general formula (C) is 1.0 × 10 relative to the total amount of the nonaqueous electrolyte solution. -3 The nonaqueous electrolyte solution according to [1], wherein the content is from 10% by mass to 10% by mass. [3] The nonaqueous electrolyte solution according to [1] or [2], wherein the content of the compound represented by the general formula (α) is 0.01 mass ppm or more and 0.5 mass % or less with respect to the total amount of the nonaqueous electrolyte solution. [4] A ratio of the total content of at least one compound selected from the compound represented by the general formula (A), the compound represented by the general formula (B), and the compound represented by the general formula (C) to the content of the compound represented by the general formula (α) in a nonaqueous electrolyte solution is 1.0 or more and 1.0 × 10 4 The nonaqueous electrolyte solution according to any one of [1] to [3], which is: [5] R 1 ~R 6 and R 7 ~R 8 The nonaqueous electrolyte solution according to any one of [1] to [4], wherein at least one of the groups is a hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond. [6] The nonaqueous electrolyte solution according to any one of [1] to [5], wherein Y is an alkenyl group having 2 to 10 carbon atoms which may have a substituent. [7] The nonaqueous electrolyte solution according to any one of [1] to [6], wherein the compound represented by general formula (C) is a compound represented by general formula (C') or a compound represented by general formula (C''). [ka] (In general formula (C'), R 12a ~R 14aeach independently represents an alkylene group having 1 to 10 carbon atoms which may have a substituent, and X a is at least a trivalent or pentavalent heteroatom. [ka] (In the general formula (C''), R 1a '~R 3a ' each independently represent a hydrocarbon group having 1 to 10 carbon atoms which may have a hetero atom, or a trialkylsilyl group which may have a substituent, and at least one of them is a hydrocarbon group having 1 to 10 carbon atoms which has a hetero atom, or a trialkylsilyl group which may have a substituent. [8] The nonaqueous electrolyte solution according to any one of [1] to [7], wherein the compound represented by the general formula (C) is triethanolamine borate or tristrimethylsilylborate. [9] A nonaqueous electrolyte battery comprising a positive electrode and a negative electrode capable of absorbing and releasing metal ions, and a nonaqueous electrolyte solution, wherein the nonaqueous electrolyte solution is the nonaqueous electrolyte solution according to any one of [1] to [8]. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain a nonaqueous electrolyte and a nonaqueous electrolyte battery that are excellent in suppressing the amount of gas generated during initial conditioning. Furthermore, in a specific embodiment of the present invention, it is possible to obtain a nonaqueous electrolyte and a nonaqueous electrolyte battery that can suppress the amount of gas generated during high-temperature storage of the nonaqueous electrolyte battery. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] <1.Non-aqueous electrolyte> A nonaqueous electrolyte according to one embodiment of the present invention contains at least one compound selected from compounds having an Si-O structure represented by general formula (A) or general formula (B) and compounds represented by general formula (C), as described below, and also contains an unsaturated silane compound represented by general formula (α). As the at least one compound selected from the compounds represented by general formula (A), the compounds represented by general formula (B), and the compounds represented by general formula (C), each compound may be used alone or in combination. The mechanism by which gas generation during initial conditioning is suppressed by using a nonaqueous electrolyte solution containing at least one compound selected from the group consisting of compounds represented by general formula (A), compounds represented by general formula (B), and compounds represented by general formula (C) and an unsaturated silane compound represented by general formula (α) is not clear, but is presumed to be as follows.

[0013] The compounds represented by general formula (A), general formula (B) or general formula (C) have a polar structure (e.g., -Si-O-, -BO-) in the molecule, and in particular, general formula (A) or (B) further have a non-polar structure (e.g., -SiR 1 R 2 R 3 ). Therefore, the compounds represented by general formula (A), general formula (B) or general formula (C) tend to interact with the surface of a negative electrode active material such as carbon and / or a positive electrode active material such as a transition metal oxide, and tend to be localized near the surface. In addition, the compounds represented by general formula (α) have an unsaturated bond with π electrons in the molecule and a non-polar structure (-SiR 9 R 10 R 11). Furthermore, silicon atoms generally have a wide electron cloud, which provides no steric hindrance to bond formation, and therefore readily form bonds with π electrons or unpaired electrons via vacant d orbitals. Therefore, compounds represented by general formula (A), general formula (B), or general formula (C) localized on the surface of the active material interact with compounds represented by general formula (α), promoting their attachment to the electrode. As a result, during the initial charge, the compounds represented by general formula (α) and the compounds represented by general formula (A), general formula (B), or general formula (C) electrochemically decompose to form a composite insulating coating. It is believed that this composite coating suppresses side reactions in the electrolyte during initial conditioning and inhibits gas generation. Furthermore, when the compound represented by general formula (α) and the compound represented by general formula (A) or general formula (B) are contained, it becomes possible to produce a battery in which the amount of gas generated during initial conditioning and high-temperature storage is small and the increase in resistance during initial conditioning is suppressed.

[0014] <1-1. Compounds with Si-O structure> A non-aqueous electrolyte solution according to one embodiment of the present invention is characterized in that it may contain a compound having an Si—O structure represented by the following general formula (A) or (B).

[0015] <1-1-1. Compound represented by general formula (A)> [ka]

[0016] In general formula (A), R 1 ~R 6 each independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an alkoxy group having 1 to 12 carbon atoms which may have a substituent, and n represents an integer of 1 to 5.

[0017] R according to general formula (A) 1 ~R 6each independently represents a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 12 carbon atoms which may have a substituent, or an alkoxy group of 1 to 12 carbon atoms which may have a substituent. Of these, a halogen atom, a hydrocarbon group of 1 to 12 carbon atoms which may have a substituent, or an alkoxy group of 1 to 12 carbon atoms which may have a substituent is preferred, and a hydrocarbon group of 1 to 12 carbon atoms which may have a substituent, or an alkoxy group of 1 to 12 carbon atoms which may have a substituent is particularly preferred. When the hydrocarbon group has a substituent, the number of carbon atoms contained in the substituent is not included in this carbon number. Also, R 1 ~R 6 At least one of the groups is preferably a hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface. Examples of the hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond include an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, which will be described later. Of these, an alkenyl group having 2 to 12 carbon atoms or an alkynyl group having 2 to 12 carbon atoms is preferred, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface, and an alkenyl group having 2 to 12 carbon atoms is particularly preferred. R according to general formula (A) 1 ~R 6 may be the same or different, but it is preferable that at least two of them are the same in terms of ease of compound synthesis, and it is more preferable that all three of them are the same in terms of the above. Examples of halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms. Fluorine atoms are preferred because they cause fewer electrochemical side reactions. The hydrocarbon group having 1 to 12 carbon atoms is preferably a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrocarbon group having 1 to 6 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 4 carbon atoms. Specific examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and an aralkyl group. Specific examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. Among these, methyl, ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, and hexyl groups are preferred, and methyl, ethyl, n-propyl, n-butyl, tert-butyl, and n-pentyl groups are more preferred, with methyl, ethyl, n-butyl, and tert-butyl being particularly preferred. The alkyl groups mentioned above are preferred because they tend to localize the compound represented by formula (A) near the surface of the positive electrode active material and / or negative electrode active material.

[0018] Specific examples of the alkenyl group include a vinyl group, an allyl group, a methallyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, a 3-butenyl group, and a 4-pentenyl group. Among these, a vinyl group, an allyl group, a methallyl group, and a 2-butenyl group are preferred, a vinyl group, an allyl group, and a methallyl group are more preferred, and a vinyl group or an allyl group is particularly preferred. 1 ~R 6 It is preferable that at least one of the groups is the above-mentioned alkenyl group, since the compound represented by general formula (A) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material.

[0019] Specific examples of the alkynyl group include an ethynyl group, a 2-propynyl group, a 2-butynyl group, a 3-butynyl group, a 4-pentynyl group, and a 5-hexynyl group. Among these, an ethynyl group, a 2-propynyl group, a 2-butynyl group, and a 3-butynyl group are preferred, a 2-propynyl group and a 3-butynyl group are more preferred, and a 2-propynyl group is particularly preferred. R 1 ~R 6 It is preferable that at least one of the groups is the above-mentioned alkynyl group, since the compound represented by general formula (A) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material.

[0020] Specific examples of the aryl group include a phenyl group and a tolyl group, etc. Among these, a phenyl group is preferred from the viewpoint that the compound represented by general formula (A) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material. Specific examples of the aralkyl group include a phenylmethyl group (benzyl group), a phenylethyl group (phenethyl group), a phenylpropyl group, a phenylbutyl group, and a phenylisopropyl group. Among these, from the viewpoint of the tendency of the compound represented by general formula (A) to be localized near the surface of the positive electrode active material and / or the negative electrode active material, a benzyl group and a phenethyl group are more preferred, and a benzyl group is particularly preferred. The alkoxy group having 1 to 12 carbon atoms is preferably an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an alkoxy group having 1 to 4 carbon atoms. Specific examples of the alkoxy group having 1 to 12 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an isopropoxy group, etc. Among these, a methoxy group or an ethoxy group is preferred because it causes less steric hindrance to the compound represented by general formula (A) and is therefore preferably concentrated on the surface of the active material.

[0021] Here, the substituents include a cyano group, an isocyanato group, an acyl group (—(C═O)—R a ), acyloxy group (-O(C=O)-R a ), alkoxycarbonyl group (-(C=O)OR a ), sulfonyl group (-SO2-R a ), sulfonyloxy group (-O(SO2)-R a ), alkoxysulfonyl group (-(SO2)-OR a ), alkoxysulfonyloxy group (-O-(SO2)-OR a ), alkoxycarbonyloxy group (-O-(C=O)-OR a ), ether group (-OR a ), halogen (preferably fluorine), or trifluoromethyl group. arepresents an alkyl group having 1 to 10 carbon atoms, an alkylene group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms. a When is an alkylene group, it may be bonded to a part of the hydrocarbon group that substitutes it to form a ring. Among these substituents, a cyano group, an isocyanato group, an acyloxy group (—O(C═O)—R a ), halogen (preferably fluorine), trifluoromethyl group, and more preferably isocyanato group, acyloxy group (—O(C═O)—R a ), halogen (preferably fluorine), or trifluoromethyl group, and particularly preferably an acyloxy group (—O(C═O)—R a ), halogen (preferably fluorine), or a trifluoromethyl group. In general formula (A), n represents an integer of 1 to 5. Among these, it is preferably an integer of 1 to 3, and more preferably 1 or 2. When n is within this range, the molecular size of the compound represented by general formula (A) is appropriate, and it is easy for the compound to interact favorably with the electrode.

[0022] <1-1-2. Compound represented by general formula (B)> [ka] In general formula (B), R 7 ~R 8 each independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, or an alkoxy group having 1 to 12 carbon atoms which may have a substituent, and k represents an integer of 3 to 6.

[0023] R according to general formula (B) 7 ~R 8 each independently represents a hydrogen atom, a halogen atom, an optionally substituted hydrocarbon group of 1 to 12 carbon atoms, or an optionally substituted alkoxy group of 1 to 12 carbon atoms. R according to general formula (B) 7 ~R 8may be the same or different, but it is preferable that they are both the same in terms of ease of compound synthesis. Here, any of a halogen atom, a hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, and an alkoxy group having 1 to 12 carbon atoms which may have a substituent is R 1 ~R 3 This is the same as that specified in

[0024] Also, R 7 ~R 8 At least one of the groups is preferably a hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface. Examples of the hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond include an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, which will be described later. Of these, an alkenyl group having 2 to 12 carbon atoms or an alkynyl group having 2 to 12 carbon atoms is preferred, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface, and an alkenyl group having 2 to 12 carbon atoms is particularly preferred. Furthermore, R in the above general formula (A) 1 ~R 6 and R in the above general formula (B) 7 ~R 8 At least one of the groups is preferably a hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface. Examples of the hydrocarbon group having 2 to 12 carbon atoms and a carbon-carbon unsaturated bond include an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, which will be described later. Of these, an alkenyl group having 2 to 12 carbon atoms or an alkynyl group having 2 to 12 carbon atoms is preferred, from the viewpoint that the compound represented by general formula (A) tends to be suitably localized on the electrode surface, and an alkenyl group having 2 to 12 carbon atoms is particularly preferred.

[0025] In formula (B), k is usually an integer of 3 to 6, and among these, 3 or 4 is preferred.

[0026] In one embodiment of the present invention, a compound represented by general formula (A) or (B) can be used, and specific examples include compounds having the following structures:

[0027] (Specific examples of compounds represented by formula (A)) [ka]

[0028] [ka]

[0029] [ka]

[0030] (Specific examples of compounds represented by formula (B))

[0031] [ka]

[0032] [ka]

[0033] Preferred examples of the compound represented by general formula (A) or (B) include the following compounds.

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] More preferred compounds include the following:

[0039] [ka]

[0040] [ka]

[0041] Particularly preferred are the following compounds:

[0042] [ka]

[0043] The total content of the compounds represented by general formula (A) or (B) relative to the total amount of the nonaqueous electrolyte solution according to one embodiment of the present invention, i.e., the content of the compounds having an Si-O structure according to this embodiment, is usually 1.0 × 10 -3 It is at least 0.01% by mass, preferably at least 0.1% by mass, more preferably at least 0.2% by mass, and is usually at most 10% by mass, preferably at most 8% by mass, more preferably at most 6.0% by mass, even more preferably at most 4.0% by mass, especially preferably at most 3.0% by mass, particularly preferably at most 2.5% by mass, and most preferably at most 2.0% by mass. When the total content of the compound represented by general formula (A) or (B) relative to the total amount of the nonaqueous electrolyte solution is within the above range, concentration of the compound represented by general formula (A) or (B) in the active material proceeds favorably, and it becomes possible to produce a battery in which the amount of gas generated during initial conditioning and high-temperature storage is small and the increase in resistance during initial conditioning is suppressed.

[0044] <1-2. Compound represented by general formula (C)> A non-aqueous electrolyte solution according to one embodiment of the present invention is characterized in that it may contain a compound having a BO structure represented by the following general formula (C).

[0045] [ka] In general formula (C), R 1a ~R 3a each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a hetero atom, or a trialkylsilyl group which may have a substituent. 1a ~R 3a may be bonded to each other to form a ring.

[0046] R according to general formula (C) 1a ~R 3a each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a heteroatom, or a trialkylsilyl group which may have a substituent. Among these, a trialkylsilyl group which may have a substituent is preferred in that it can interact favorably with the compound represented by general formula (α). The hydrocarbon group that may have a heteroatom means that the hydrocarbon group may have a substituent containing a monovalent heteroatom substituting a hydrogen atom, or may have a divalent substituent containing a heteroatom substituting a divalent group containing a carbon atom (e.g., a methylene group) in the hydrocarbon group. Furthermore, when one or more carbon atoms in the hydrocarbon group have an oxo group (=O) as a substituent, the carbon atom containing the oxo group becomes a carbonyl group {—C(=O)—}. Here, when the hydrocarbon group has a substituent, the number of carbon atoms contained in the substituent is not included in this carbon number. The hydrocarbon group having 1 to 10 carbon atoms is preferably a hydrocarbon group having 1 to 6 carbon atoms, and particularly preferably a hydrocarbon group having 1 to 4 carbon atoms.

[0047] Specific examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and an aralkyl group. Specific examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. Among these, methyl, ethyl, n-propyl, n-butyl, tert-butyl, n-pentyl, and hexyl groups are preferred, methyl, ethyl, n-propyl, n-butyl, tert-butyl, and n-pentyl groups are more preferred, and methyl, ethyl, n-butyl, and tert-butyl groups are particularly preferred. The hydrocarbon group is preferably an alkyl group as described above, since the compound represented by formula (C) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material.

[0048] Specific examples of the alkenyl group include a vinyl group, an allyl group, a methallyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, a 3-butenyl group, and a 4-pentenyl group. Among these, a vinyl group, an allyl group, a methallyl group, and a 2-butenyl group are preferred, a vinyl group, an allyl group, and a methallyl group are more preferred, and a vinyl group or an allyl group is particularly preferred. If the hydrocarbon group is the above-mentioned alkenyl group, the compound represented by general formula (C) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material, which is preferable.

[0049] Specific examples of the alkynyl group include an ethynyl group, a 2-propynyl group, a 2-butynyl group, a 3-butynyl group, a 4-pentynyl group, and a 5-hexynyl group. Among these, an ethynyl group, a 2-propynyl group, a 2-butynyl group, and a 3-butynyl group are preferred, a 2-propynyl group and a 3-butynyl group are more preferred, and a 2-propynyl group is particularly preferred. When the hydrocarbon group is an alkynyl group as described above, the compound represented by general formula (A) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material, which is preferable.

[0050] Specific examples of the aryl group include a phenyl group and a tolyl group, etc. Among these, a phenyl group is preferred from the viewpoint that the compound represented by general formula (C) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material. Specific examples of the aralkyl group include a phenylmethyl group (benzyl group), a phenylethyl group (phenethyl group), a phenylpropyl group, a phenylbutyl group, a phenylisopropyl group, etc. Among these, a benzyl group or a phenethyl group is more preferred, and a benzyl group is particularly preferred, from the viewpoint that the compound represented by general formula (C) tends to be localized near the surface of the positive electrode active material and / or the negative electrode active material.

[0051] Here, examples of the heteroatom include an oxygen atom, a sulfur atom, a nitrogen atom, a phosphorus atom, and a halogen atom. Examples of monovalent substituents containing heteroatoms include cyano groups, isocyanato groups, and acyl groups (-(C=O)-R a ), acyloxy group (-O(C=O)-R a ), alkoxycarbonyl group (-(C=O)OR a ), sulfonyl group (-SO2-R a ), sulfonyloxy group (-O(SO2)-R a ), alkoxysulfonyl group (-(SO2)-OR a ), alkoxysulfonyloxy group (-O-(SO2)-OR a ), alkoxycarbonyloxy group (-O-(C=O)-OR a ), ether group (-OR a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group. a represents an alkyl group having 1 to 10 carbon atoms, an alkylene group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms. a When is an alkylene group, it may be bonded to a part of the hydrocarbon group that substitutes it to form a ring. Among these substituents, a cyano group, an isocyanato group, an acyloxy group (—O(C═O)—R a), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, and more preferably an isocyanato group, an acyloxy group (—O(C═O)—R a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, and particularly preferably an acyloxy group (—O(C═O)—R a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, and particularly preferably a fluorine atom. Examples of the heteroatom of the divalent substituent containing a heteroatom substituting a group containing a carbon atom (e.g., a methylene group) in the hydrocarbon group include an oxygen atom, a sulfur atom, a nitrogen atom, and a phosphorus atom. From the viewpoint of strengthening the interaction with the compound represented by general formula (α), a phosphorus atom or a nitrogen atom is preferred, and a nitrogen atom is particularly preferred. Note that R 1a ~R 3a When any one of the above has a heteroatom, the lone electron pair of the heteroatom may be coordinated to the boron atom.

[0052] Specific examples of the trialkylsilyl group include a trimethylsilyl group, a triethylsilyl group, a tripropylsilyl group, a tributylsilyl group, a triisopropylsilyl group, and a tert-butyldimethylsilyl group. From the viewpoint of favorable interaction with the compound represented by general formula (α), a trimethylsilyl group or a triethylsilyl group is preferred. The substituent that the trialkylsilyl group may have may be a hydrocarbon group having an unsaturated bond, such as an alkenyl group, an alkynyl group, an aryl group, or an aralkyl group, or a substituent containing a monovalent heteroatom that substitutes a hydrogen atom of an alkyl group bonded to the Si atom of the trialkylsilyl group. Examples of monovalent substituents containing heteroatoms include cyano groups, isocyanato groups, and acyl groups (-(C=O)-R b ), acyloxy group (-O(C=O)-R b ), alkoxycarbonyl group (-(C=O)OR b ), sulfonyl group (-SO2-R b ), sulfonyloxy group (-O(SO2)-R b), alkoxysulfonyl group (-(SO2)-OR b ), alkoxysulfonyloxy group (-O-(SO2)-OR a ), alkoxycarbonyloxy group (-O-(C=O)-OR b ), ether group (-OR b ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group. a represents an alkyl group having 1 to 10 carbon atoms, an alkylene group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms. a When is an alkylene group, it may be bonded to a part of the hydrocarbon group that substitutes it to form a ring. Among these substituents that the trialkylsilyl group may have, an alkenyl group, an alkynyl group, a cyano group, an isocyanato group, an acyloxy group (—O(C═O)—R a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, and more preferably an isocyanato group, an acyloxy group (—O(C═O)—R a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, and particularly preferably an alkenyl group, an acyloxy group (—O(C═O)—R a ), a halogen atom (preferably a fluorine atom), or a trifluoromethyl group, particularly preferably a fluorine atom.

[0053] Also, R 1a ~R 3a may be bonded to each other to form a ring. 1a ~R 3a are bonded to each other to form a ring, R 1a ~R 3a Two of the groups may be bonded to each other to form a ring, or R 1a ~R 3a All combinations of may be linked together.

[0054] R according to general formula (C) 1a ~R 3amay be the same or different, but it is preferable that at least two or more are the same in terms of ease of compound synthesis, and it is more preferable that all three are the same from the above-mentioned viewpoint. In addition, from the viewpoint that the compound represented by general formula (C) easily interacts sterically with the compound represented by general formula (α), R 1a ~R 3a It is also preferred that at least two of R 1a ~R 3a More preferably, R are bonded to each other to form a ring, 1a ~R 3a More preferably, are bonded to each other via a heteroatom to form a ring.

[0055] In the compound represented by general formula (C), R 1a ~R 3a The boron-containing cyclic compound in which the groups bond to each other via a hetero atom to form a ring is specifically a compound represented by the general formula (C').

[0056] [ka]

[0057] R according to general formula (C') 12a ~R 14a are each independently an alkylene group having 1 to 10 carbon atoms which may have a substituent, preferably an alkylene group having 1 to 6 carbon atoms, and particularly preferably an alkylene group having 2 to 4 carbon atoms. 1a ~R 3a Examples of the substituent include alkylene groups obtained by removing one hydrogen atom from the alkyl groups exemplified above. Examples include methylene, methylmethylene, ethylmethylene, dimethylmethylene, diethylmethylene, methylethylene, dimethylene (ethylene), trimethylene (propylene), and tetramethylene (butylene). Specific examples of the substituent include the groups exemplified as monovalent substituents containing heteroatoms.

[0058] X ais at least a trivalent or pentavalent heteroatom, such as a phosphorus atom (P), P=O, or a nitrogen atom (N). A nitrogen atom is particularly preferred. The lone electron pair of the heteroatom X may be coordinated to boron. R according to general formula (C') 12a ~R 14a may be the same or different, but it is preferable that at least two of them are the same in terms of ease of compound synthesis, and it is more preferable that all three of them are the same in terms of the above.

[0059] Among the compounds represented by general formula (C), preferred compounds are those represented by the above general formula (C') or the following general formula (C'').

[0060] [ka]

[0061] In the general formula (C''), R 1a '~R 3a ' each independently represent a hydrocarbon group having 1 to 10 carbon atoms which may have a heteroatom, or a trialkylsilyl group which may have a substituent, and at least one of them is a hydrocarbon group having 1 to 10 carbon atoms which has a heteroatom, or a trialkylsilyl group which may have a substituent. R 1a '~R 3a ' is the R 1a ~R 3a and the preferred conditions can be applied in the same manner.

[0062] The compound represented by the formula (C') above is preferably triethanolamine borate, which will be described later, and the compound represented by the formula (C'') above is preferably tristrimethylsilylborate, which will be described later.

[0063] In one embodiment of the present invention, a compound represented by general formula (C) can be used, and specific examples include compounds having the following structures:

[0064] [ka]

[0065] Preferred examples of the compounds include the following:

[0066] [ka]

[0067] More preferred compounds include the following:

[0068] [ka]

[0069] Particularly preferred are the following compounds:

[0070] [ka]

[0071] Among these, particularly preferred are triethanolamine borate, which is a boron-containing cyclic compound, and tristrimethylsilylborate, which is a borate ester compound having a trialkylsilyl group.

[0072] The compound represented by formula (C) may be used alone or in combination of two or more kinds. The total content of the compounds represented by general formula (C) relative to the total amount of the nonaqueous electrolyte solution according to one embodiment of the present invention is usually 1.0 × 10 -3 It is % by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and is usually 10% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. When the total content of the compounds represented by general formula (C) relative to the total amount of the nonaqueous electrolyte solution is within the above range, the concentration of the compounds in the active material proceeds favorably, and it becomes possible to produce a battery that generates little gas during initial conditioning.

[0073] The total content of at least one compound selected from the group consisting of the compound represented by general formula (A), the compound represented by general formula (B), and the compound represented by general formula (C) relative to the total amount of the nonaqueous electrolyte solution according to one embodiment of the present invention is usually 1.0 × 10 -3 It is % by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and is usually 10% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. When the total content of the above compounds relative to the total amount of the nonaqueous electrolyte solution is within the above range, the concentration of the compounds in the active material proceeds favorably, making it possible to produce a battery that generates less gas during initial conditioning.

[0074] <1-3. Compound represented by general formula (α)> A non-aqueous electrolyte solution according to one embodiment of the present invention is characterized by containing an unsaturated silane compound represented by general formula (α).

[0075] [ka]

[0076] In general formula (α), R 9 ~R 11 each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, an optionally substituted aryl group having 6 to 18 carbon atoms, or an optionally substituted aralkyl group having 7 to 18 carbon atoms; and Y represents an optionally substituted alkenyl group or alkynyl group having 2 to 10 carbon atoms.

[0077] Here, the substituents include a cyano group, an isocyanato group, an acyl group (—(C═O)—R a), acyloxy group (-O(C=O)-R a ), alkoxycarbonyl group (-(C=O)OR a ), sulfonyl group (-SO2-R a ), sulfonyloxy group (-O(SO 2 )-R a ), alkoxysulfonyl group (-(SO2)-OR a ), alkoxycarbonyloxy group (-O-(C=O)-OR a ), ether group (-OR a ), an acrylic group, a methacrylic group, a halogen (preferably fluorine), or a trifluoromethyl group. a represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms. The carbon atoms in these substituents are 9 ~R 11 and is not counted as the number of carbon atoms in the hydrocarbon group of Y having 1 to 12 carbon atoms.

[0078] Among these substituents, a cyano group, an isocyanato group, an acyl group (—(C═O)—R a ), acyloxy group (-O(C=O)-R a ), alkoxycarbonyl group (-(C=O)OR a ), and more preferably a cyano group, an isocyanato group, an acyl group (—(C═O)—R a ), or an alkoxycarbonyl group (-(C=O)OR a ), and particularly preferably a cyano group, an isocyanato group, or an alkoxycarbonyl group (—(C═O)OR a ), and most preferably a cyano group.

[0079] Specific examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an n-pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group. Among these, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a tert-butyl group, an n-pentyl group, or a hexyl group is preferred, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, a tert-butyl group, or an n-pentyl group is more preferred, and a methyl group or an ethyl group is particularly preferred.

[0080] Specific examples of the aryl group having 6 to 18 carbon atoms include a phenyl group, a tolyl group, etc. Among these, a phenyl group is preferred because it facilitates concentration in the active material. Specific examples of the aralkyl group having 7 to 18 carbon atoms include a phenylmethyl group (benzyl group), a phenylethyl group (phenethyl group), a phenylpropyl group, a phenylbutyl group, and a phenylisopropyl group. Among these, from the viewpoint of the tendency of the compound represented by general formula (α) to be localized near the surface of the positive electrode active material and / or the negative electrode active material, benzyl group and phenethyl group are preferred, and benzyl group is particularly preferred.

[0081] Specific examples of alkenyl groups having 2 to 10 carbon atoms include vinyl, allyl, methallyl, 2-butenyl, 3-methyl-2-butenyl, 3-butenyl, and 4-pentenyl groups. Among these, vinyl, allyl, methallyl, and 2-butenyl groups are preferred, vinyl, allyl, and methallyl groups are more preferred, and allyl and methallyl groups are particularly preferred. The above-mentioned alkenyl groups are preferred because they allow for the formation of an insulating coating film.

[0082] Specific examples of alkynyl groups having 2 to 10 carbon atoms include ethynyl, 2-propynyl, 2-butynyl, 3-butynyl, 4-pentynyl, and 5-hexynyl groups. Among these, ethynyl, 2-propynyl, 2-butynyl, and 3-butynyl groups are preferred, ethynyl, 2-propynyl, and 3-butynyl groups are more preferred, and ethynyl and 2-propynyl groups are particularly preferred. The above-mentioned alkynyl groups are preferred because they allow for the formation of an insulating coating film.

[0083] Since the compound represented by general formula (α) and the compound represented by general formula (A), (B), or (C) tend to interact favorably, R 9 ~R 11 At least one of R is an alkyl group having 1 to 10 carbon atoms which may have a substituent, preferably at least two are alkyl groups having 1 to 10 carbon atoms which may have a substituent, more preferably all are alkyl groups having 1 to 10 carbon atoms which may have a substituent, and most preferably a methyl group or an ethyl group. 9 ~R 11 If any one of the groups is a methyl group, then R 9 ~R 11 It is not necessary that all of R are methyl groups. For example, the following combinations are preferable: 9 , R 10 , R 11 ): (methyl, methyl, ethyl), (methyl, methyl, n-butyl), (methyl, methyl, tert-butyl), (methyl, methyl, phenyl), (methyl, ethyl, ethyl), (methyl, phenyl, phenyl).

[0084] In general formula (α), Y is preferably an alkenyl group having 2 to 10 carbon atoms which may have a substituent, more preferably an alkenyl group having 2 to 10 carbon atoms, still more preferably a vinyl group, an allyl group, or a methallyl group, and particularly preferably an allyl group or a methallyl group, because this allows for the suitable formation of an insulating coating.

[0085] Specific examples of the compound represented by general formula (α) include compounds having the following structures.

[0086] [ka]

[0087] More preferred are compounds having the following structures: The compounds having the following structures are more likely to interact favorably with the compounds represented by general formula (A), (B) or (C).

[0088] [ka]

[0089] Particularly preferred are compounds having the following structures: The compounds having the following structures are more likely to interact favorably with the compounds represented by general formula (A), (B) or (C).

[0090] [ka]

[0091] Most preferably, compounds having the following structure are mentioned: Compounds having the following structure are highly reactive and suitably form insulating layers.

[0092] [ka]

[0093] The total content of the compounds represented by general formula (α) relative to the total amount of the nonaqueous electrolyte solution according to one embodiment of the present invention is usually 0.01 mass ppm or more, preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, and is usually 5 mass% or less, preferably 2 mass% or less, more preferably 1 mass% or less, even more preferably 0.5 mass% or less, particularly preferably less than 0.5 mass%, particularly preferably 0.2 mass% or less, and most preferably 0.1 mass% or less. When the total content of the compound represented by general formula (α) relative to the total amount of the nonaqueous electrolyte solution is within the above range, the concentration of the compound represented by general formula (α) in the active material proceeds favorably, and it becomes possible to produce a battery that generates less gas during initial conditioning. Furthermore, the ratio of the total content of at least one compound selected from the compound represented by general formula (A), the compound represented by general formula (B), and the compound represented by general formula (C) in the non-aqueous electrolyte solution (the total content of the compounds represented by general formulas (A), (B), or (C)) to the content of the compound represented by general formula (α) is preferably 1.0 or more, more preferably 1.5 or more, even more preferably 2.0 or more, particularly preferably 3.0 or more, and most preferably 5.0 or more, and is preferably 1.0 × 10 4 Less than or equal to 0.5 × 10 4 or less, more preferably 1.0 × 10 3 The following is the result.

[0094] <1-4. Electrolytes> The nonaqueous electrolyte solution of this embodiment, like a general nonaqueous electrolyte solution, typically contains an electrolyte as a component. The electrolyte used in the nonaqueous electrolyte solution of this embodiment is not particularly limited as long as it is an alkali metal salt, and lithium salts such as LiBF, LiPF, LiN(FSO), LiN(CFSO), or lithium difluorooxalatoborate can be suitably used. These lithium salts can also be used alone or in combination of two or more.

[0095] The total concentration of the alkali metal salts in the non-aqueous electrolyte is not particularly limited, but is usually 8% by mass or more, preferably 8.5% by mass or more, more preferably 9% by mass or more, based on the total amount of the non-aqueous electrolyte. The upper limit is usually 18% by mass or less, preferably 17% by mass or less, more preferably 16% by mass or less. When the total concentration of the alkali metal salts as the electrolyte is within the above range, the electrical conductivity is appropriate for battery operation, and sufficient output characteristics tend to be obtained.

[0096] <1-4. Non-aqueous solvents> The non-aqueous electrolyte solution of this embodiment, like a general non-aqueous electrolyte solution, usually contains a non-aqueous solvent that dissolves the above-mentioned electrolyte as its main component. There are no particular limitations on the non-aqueous solvent, and known organic solvents can be used. Examples of organic solvents include saturated cyclic carbonates such as ethylene carbonate, propylene carbonate, or butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate; carboxylic acid esters such as methyl acetate, ethyl acetate, propyl acetate, or butyl acetate; ether compounds such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, tetrahydrofuran, 1,3-dioxane, or 1,4-dioxane; sulfone compounds such as 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, dimethyl sulfone, ethyl methyl sulfone, or monofluoromethyl methyl sulfone; and the like. Preferred are saturated cyclic carbonates, chain carbonates, and carboxylic acid esters, and more preferred are saturated cyclic carbonates and chain carbonates. These non-aqueous solvents can be used alone or in combination of two or more.

[0097] <1-5. Auxiliaries> The nonaqueous electrolyte solution of this embodiment may contain an auxiliary agent within a range that allows the effects of the present invention to be achieved. As an auxiliary agent, fluorinated salts such as difluorophosphates, fluorosulfonates, fluoroboronates or fluoroimide salts; unsaturated cyclic carbonates such as vinylene carbonate, vinylethylene carbonate, or ethynylethylene carbonate; fluorinated cyclic carbonates such as monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4,5-difluoro-4,5-dimethylethylene carbonate; oxalate salts such as lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, or lithium tris(oxalato)phosphate; Carbonate compounds such as methoxyethyl-methyl carbonate; Spiro compounds such as methyl-2-propynyl oxalate; Sulfur-containing compounds such as ethylene sulfite; Diisocyanates having a cycloalkylene group, such as 1,3-bis(isocyanatomethyl)cyclohexane; isocyanate compounds such as trimer compounds derived from compounds having at least two isocyanate groups in the molecule, such as triallyl isocyanurate, or aliphatic polyisocyanates obtained by adding a polyhydric alcohol thereto; Nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone; hydrocarbon compounds such as cycloheptane; Fluorinated aromatic compounds such as fluorobenzene; fluorosilane compounds such as fluorotrimethylsilane, fluorodimethylvinylsilane, difluorodimethylsilane, or difluorovinylmethylsilane; Ester compounds such as 2-propynyl 2-(methanesulfonyloxy)propionate; Lithium salts such as lithium ethylmethyloxycarbonylphosphonate; These may be used alone or in combination of two or more. The addition of these auxiliary agents can suppress gas generation during initial conditioning and improve capacity retention and cycle characteristics after high-temperature storage.

[0098] In particular, in the nonaqueous electrolyte solution according to one embodiment of the present invention, the use of one or more selected from fluorinated salts, unsaturated cyclic carbonates, cyclic carbonates having fluorine atoms, and oxalate salts is preferred in that gas generation during initial conditioning is further suppressed and a battery that is less likely to swell can be obtained. More preferably, the composition contains at least an unsaturated cyclic carbonate or a cyclic carbonate having a fluorine atom, and even more preferably, the composition contains an unsaturated cyclic carbonate and a cyclic carbonate having a fluorine atom. Furthermore, it is also preferable to contain at least an unsaturated cyclic carbonate or a fluorine-containing cyclic carbonate and one or more selected from a fluorinated salt, a fluorosilane compound, and an oxalate salt, since this further suppresses gas generation during initial conditioning, thereby obtaining a battery that is less prone to swelling and also reduces the initial resistance of the battery. Furthermore, it is more preferable to contain an unsaturated cyclic carbonate and a fluorine-containing cyclic carbonate and one or more selected from a fluorinated salt, a fluorosilane compound, and an oxalate salt. The content of the auxiliary agent 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 0.2% by mass or more, relative to 100% by mass of the nonaqueous electrolyte solution, and is usually 10% by mass or less, preferably 8% by mass or less, and more preferably 5% by mass or less. When two or more auxiliary agents are used in combination, it is preferable that the total content satisfies the above range. The "fluorinated salts," "fluorosilane compounds," "unsaturated cyclic carbonates," "fluorinated cyclic carbonates," and "oxalate salts" will be described in detail below.

[0099] (fluorinated salts) The nonaqueous electrolyte solution according to this embodiment may contain a fluorinated salt. While there are no particular limitations on the fluorinated salt, difluorophosphates, fluorosulfonates, fluoroboron salts, or fluoroimide salts are preferred because they contain fluorine atoms with high releasability in their structure, allowing them to react favorably with the decomposition products of the compounds represented by general formula (A), (B), or (α) to form a composite coating, thereby reducing the initial battery resistance. Fluoroboron salts, fluorosulfonates, or difluorophosphates are more preferred because they have particularly high releasability of fluorine atoms and favorably react with nucleophiles, with fluorosulfonates or difluorophosphates being particularly preferred. Fluorosulfonates are most preferred because of their high releasability of fluorine. Furthermore, fluorinated lithium salts are preferred as the fluorinated salt. The fluorinated salt may be used alone or in any combination and ratio of two or more. The content of the fluorinated salt relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and is usually less than 8% by mass, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and most preferably 1% by mass or less. These various salts will be explained below.

[0100] <Difluorophosphate> The counter cation of the difluorophosphate is not particularly limited, but may be lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, or NR 27 R 28 R 29 R 30 (In the formula, R 27 ~R 30 and each independently represent a hydrogen atom or an organic group having 1 to 12 carbon atoms. Examples include ammonium represented by the following formula: Among these, lithium is preferred.

[0101] The above ammonium R 27~R 30 The organic group having 1 to 12 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom or an alkyl group, an aryl group which may be substituted with a halogen atom or an alkyl group, or a nitrogen atom-containing heterocyclic group which may have a substituent. 27 ~R 30 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group.

[0102] Specific examples of difluorophosphates include lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate, with lithium difluorophosphate being preferred. The difluorophosphate may be used alone or in any combination and ratio of two or more. The content of the difluorophosphate relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and is usually less than 8% by mass, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and most preferably 1% by mass or less. When the content of the difluorophosphate is within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and it is also likely to avoid situations such as a deterioration in high-temperature storage characteristics, an increase in the amount of gas generated, and a decrease in the discharge capacity retention rate.

[0103] <Fluorosulfonate> The counter cation of the fluorosulfonate is not particularly limited, but may be lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, or NR 17 R 18 R 19 R 20 (In the formula, R 17 ~R 20and each independently represent a hydrogen atom or an organic group having 1 to 12 carbon atoms. Examples include ammonium represented by the following formula: Among these, lithium is preferred.

[0104] The above ammonium R 17 ~R 20 The organic group having 1 to 12 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom or an alkyl group, an aryl group which may be substituted with a halogen atom or an alkyl group, or a nitrogen atom-containing heterocyclic group which may have a substituent. 17 ~R 20 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group. Specific examples of fluorosulfonates include: Examples of the fluorosulfonate include lithium fluorosulfonate, sodium fluorosulfonate, potassium fluorosulfonate, rubidium fluorosulfonate, and cesium fluorosulfonate, and lithium fluorosulfonate is preferred.

[0105] The fluorosulfonate may be used alone or in any combination and ratio of two or more. The content of the fluorosulfonate relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and is usually less than 8% by mass, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and most preferably 1% by mass or less. When the content of the fluorosulfonate is within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and it is also likely to avoid situations such as a deterioration in high-temperature storage characteristics, an increase in the amount of gas generated, and a decrease in the discharge capacity retention rate.

[0106] <Fluoroboron salt> The counter cation of the fluoroboron salt is not particularly limited, but may be lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, or NR 21 R 22 R 23 R 24 (In the formula, R 21 ~R 24 and each independently represent a hydrogen atom or an organic group having 1 to 12 carbon atoms. Examples include ammonium represented by the following formula: Among these, lithium is preferred.

[0107] The above ammonium R 21 ~R 24 The organic group having 1 to 12 carbon atoms represented by the formula (I) is not particularly limited, but examples thereof include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom or an alkyl group, an aryl group which may be substituted with a halogen atom or an alkyl group, or a nitrogen atom-containing heterocyclic group which may have a substituent. 21 ~R 24 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group.

[0108] Specific examples of fluoroboron salts include: LiBF4, LiB(C i F 2i+1 ) j (F) 4-j In addition, i represents an integer of 1 to 10, and j represents an integer of 1 to 4. The fluoroboron salt may be used alone or in any combination and ratio of two or more. The content of the fluoroboron salt relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and usually 3% by mass or less, preferably 1% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.5% by mass or less, and most preferably 0.3% by mass or less. If the content of the fluoroboron salt is within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and it is also likely to avoid situations such as a deterioration in high-temperature storage characteristics, an increase in the amount of gas generated, and a decrease in the discharge capacity retention rate.

[0109] <Fluoroimide salt> The counter cation of the fluoroimide salt is not particularly limited, but may be lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, or NR 31 R 32 R 33 R 34 (In the formula, R 31 ~R 34 are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms. Examples include ammonium represented by the following formula: Among these, lithium is preferred.

[0110] The above ammonium R 31 ~R 34 The organic group having 1 to 12 carbon atoms represented by is not particularly limited, but examples thereof include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom or an alkyl group, an aryl group which may be substituted with a halogen atom or an alkyl group, or a nitrogen atom-containing heterocyclic group which may have a substituent. 31 ~R 34 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group.

[0111] Specific examples of fluoroimide salts include LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, or LiN(CF3SO2)(C4F9SO2), with LiN(FSO2)2, LiN(CF3SO2)2, and LiN(C2F5SO2)2 being preferred.

[0112] The fluoroimide salt may be used alone or in any combination and ratio of two or more. The content of the fluoroimide salt relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and is usually less than 8% by mass, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and most preferably 1% by mass or less. When the content of the fluoroimide salt is within this range, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and it is also likely to avoid situations such as a deterioration in high-temperature storage characteristics, an increase in the amount of gas generated, and a decrease in the discharge capacity retention rate.

[0113] (oxalate salt) Oxalate salts are preferred in that they can react favorably with the decomposition products of the compounds represented by general formula (A), (B), or (α) to form a composite coating, thereby reducing the initial battery resistance. The counter cation of the oxalate salt is not particularly limited, but may be lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, or NR 35 R 36 R 37 R 38 (In the formula, R 35 ~R 38 are each independently a hydrogen atom or an organic group having 1 to 12 carbon atoms. Examples include ammonium represented by the following formula: Among these, lithium is preferred.

[0114] The above ammonium R 35 ~R 38The organic group having 1 to 12 carbon atoms represented by is not particularly limited, but examples thereof include an alkyl group which may be substituted with a halogen atom, a cycloalkyl group which may be substituted with a halogen atom or an alkyl group, an aryl group which may be substituted with a halogen atom or an alkyl group, or a nitrogen atom-containing heterocyclic group which may have a substituent. 35 ~R 38 are each preferably independently a hydrogen atom, an alkyl group, a cycloalkyl group, or a nitrogen atom-containing heterocyclic group.

[0115] Specific examples of oxalate salts include lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate, with lithium bis(oxalato)borate and lithium difluorobis(oxalato)phosphate being preferred, and lithium bis(oxalato)borate being particularly preferred.

[0116] The oxalate salt may be used alone or in any combination and ratio of two or more. The content of the oxalate salt relative to the total amount of the non-aqueous electrolyte 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, more preferably 0.1% by mass or more, and is usually less than 8% by mass, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and most preferably 1% by mass or less. When the content of the oxalate salt is within this range, the effect of reducing the initial battery resistance is enhanced, and further, the nonaqueous electrolyte secondary battery is likely to exhibit a sufficient effect of improving the cycle characteristics, and it is also likely to avoid situations such as a deterioration in high-temperature storage characteristics, an increase in the amount of gas generated, and a decrease in the discharge capacity retention rate.

[0117] (fluorosilane compounds) The fluorosilane compound is preferable in that it can react favorably with the decomposition product of the compound represented by general formula (A), (B), or (α) to form a composite coating film, thereby reducing the initial battery resistance. The nonaqueous electrolyte solution according to this embodiment may contain a fluorosilane compound. The fluorosilane compound is not particularly limited as long as it has at least one silicon-fluorine bond (Si-F bond) in the molecule. Examples of fluorosilane compounds include fluorotrimethylsilane, dimethyl(fluoro)(vinyl)silane, (allyl)dimethyl(fluoro)silane, dimethyl(fluoro)(propargyl)silane, divinylfluoro(methyl)silane, fluorotrivinylsilane, ethynyldimethylfluorosilane, difluorodimethylsilane, difluorodivinylsilane, methyltrifluorosilane, trifluorovinylsilane, fluorotriethylsilane, diethyl(fluoro)(methyl)silane, diethyl(fluoro)(vinyl)silane, ethyldivinylfluorosilane, diethyl(fluoro)(ethynyl)silane, (allyl)diethyl(fluoro)silane, diethyl(fluoro)(propargyl)silane, difluorodiethylsilane, ethyldifluorovinylsilane, and trifluoroethylsilane. Examples of compounds include thylsilane, fluorotripropylsilane, trifluoropropylsilane, fluorotributylsilane, trifluorobutylsilane, fluorotripentylsilane, trifluoropentylsilane, fluorotrihexylsilane, trifluorohexylsilane, fluorotricyclohexylsilane, trifluorocyclohexylsilane, fluorotriphenylsilane, fluorotritriylsilane, fluorotribenzylsilane, difluorodinaphthylsilane, naphthyltrifluorosilane, dibiphenyldifluorosilane, biphenyltrifluorosilane, (cyclohexylphenyl)trifluorosilane, di(cyclohexylphenyl)difluorosilane, fluorotri(biphenyl)silane, and fluorotri(cyclohexylphenyl)silane.

[0118] Of these, preferred is fluorotrimethylsilane, dimethyl(fluoro)(vinyl)silane, dimethyldifluorosilane, or methyl(difluoro)(vinyl)silane.

[0119] The fluorosilane compound may be used alone or in any combination and ratio of two or more. The content of the fluorosilane compound (total amount when two or more types are used) is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, based on the total amount of the nonaqueous electrolyte solution, and is usually 3% by mass or less, preferably 1% by mass or less, more preferably 0.5% by mass or less. Within this range, the effect of reducing the initial battery resistance is enhanced, and further, it is easy to control the output characteristics, load characteristics, low-temperature characteristics, cycle characteristics, high-temperature storage characteristics, etc.

[0120] (Unsaturated cyclic carbonate) In this specification, the term "unsaturated cyclic carbonate" refers to a cyclic carbonate having a carbon-carbon unsaturated bond, and is not particularly limited as long as it is a carbonate having a carbon-carbon unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond, and any unsaturated cyclic carbonate can be used. Examples of unsaturated cyclic carbonates include vinylene carbonates and ethylene carbonates substituted with a substituent having a carbon-carbon unsaturated bond. Specific examples of vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, and 4,5-dimethyl vinylene carbonate. Specific examples of ethylene carbonates substituted with a substituent having a carbon-carbon unsaturated bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, ethynyl ethylene carbonate, and propargyl ethylene carbonate. Among these, vinylene carbonate, vinylethylene carbonate, or ethynylethylene carbonate is preferred, and vinylene carbonate is particularly preferred because it can contribute to the formation of a stable film-like structure. The molecular weight of the unsaturated cyclic carbonate is not particularly limited and may be any value as long as it does not significantly impair the effects of the present invention, but is usually at least 50, preferably at least 80, and usually at most 250, preferably at most 150. Within these ranges, the solubility of the unsaturated cyclic carbonate in the nonaqueous electrolyte solution is easily ensured, and the effects of the present invention are 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 as long as it does not significantly impair the effects of the present invention. The content of the unsaturated cyclic carbonate is usually 0.001 mass% or more, preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.2 mass% or more, based on the total amount of the non-aqueous electrolyte solution. The content of the unsaturated cyclic carbonate within the above range enhances the effect of reducing the initial resistance of the non-aqueous electrolyte secondary battery, and is also likely to exhibit sufficient effects of improving high-temperature storage characteristics and cycle characteristics.

[0121] (Fluorinated cyclic carbonate) As used herein, the term "fluorinated cyclic carbonate" refers to a cyclic carbonate containing 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. 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. The fluorinated cyclic carbonate may be used alone or as a mixture of two or more kinds in any combination and ratio. 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 80% by mass or less, more preferably 75% by mass or less, based on the total amount of the non-aqueous electrolyte solution. Within this range, the effect of reducing the initial resistance of the non-aqueous electrolyte secondary battery is enhanced, and further, sufficient cycle characteristics are easily improved, and a decrease in the discharge capacity retention rate is easily avoided. In the nonaqueous electrolyte solution according to one embodiment of the present invention, the unsaturated cyclic carbonate or fluorinated cyclic carbonate is preferably at least one selected from the group consisting of vinylene carbonate, vinylethylene carbonate, ethynylethylene carbonate, and fluoroethylene carbonate.

[0122] 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. 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. The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and may be any value as long as it does not significantly impair the effects of the present invention, but is usually at least 50, preferably at least 80, and usually at most 250, preferably at most 150. Within these ranges, the solubility of the fluorinated cyclic carbonate in the nonaqueous electrolyte solution is easily ensured, and the effects of the present invention are easily exhibited. 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, but 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 4% by mass or less, more preferably 3% by mass or less, based on the total amount of the non-aqueous electrolyte. Within this range, the effect of reducing the initial resistance of the non-aqueous electrolyte secondary battery is enhanced, and further, the effect of sufficiently improving the cycle characteristics is easily exhibited.

[0123] The amount of auxiliary agents other than fluorinated salts, fluorosilane compounds, unsaturated cyclic carbonates, fluorinated cyclic carbonates, and oxalate salts (content of other auxiliary agents) is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present invention. However, based on the total amount of the non-aqueous electrolyte solution, it 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. Within this range, the effects of the other auxiliary agents are easily exerted, and high-temperature storage stability tends to be improved. When two or more other auxiliary agents are used in combination, the total amount of the other auxiliary agents should be within the above range.

[0124] <2.Nonaqueous electrolyte battery> A nonaqueous electrolyte battery according to one embodiment of the present invention is a nonaqueous electrolyte battery comprising a positive electrode and a negative electrode capable of absorbing and releasing metal ions, and a nonaqueous electrolyte solution, and the battery comprises the nonaqueous electrolyte solution according to the embodiment of the present invention described above. More specifically, the battery comprises a current collector and a positive electrode having a positive electrode active material layer on at least a portion of the current collector surface and capable of absorbing and releasing metal ions, a current collector and a negative electrode having a negative electrode active material layer on at least a portion of the current collector surface and capable of absorbing and releasing metal ions, and the nonaqueous electrolyte solution contains a compound represented by the general formula (1) described above together with an alkali metal salt and a nonaqueous solvent.

[0125] <2-1. Battery configuration> The nonaqueous electrolyte battery of this embodiment is similar to conventional nonaqueous electrolyte batteries in terms of configuration other than the nonaqueous electrolyte. Typically, a positive electrode and a negative electrode are stacked via a porous membrane (separator) impregnated with the nonaqueous electrolyte, and these are housed in a case (exterior body). The shape of the nonaqueous electrolyte battery of this embodiment is not particularly limited, and may be any of cylindrical, rectangular, laminated, coin, large, and the like.

[0126] <2-2. Non-aqueous electrolyte> As the nonaqueous electrolyte solution, the nonaqueous electrolyte solution according to one embodiment of the present invention is used. Note that, within the scope of the present invention, other nonaqueous electrolyte solutions may be blended with the nonaqueous electrolyte solution.

[0127] <2-3. Positive electrode> The positive electrode refers to a current collector having a positive electrode active material on at least a portion of the surface of the current collector. The other components may be conventionally known.

[0128] The positive electrode active material is not particularly limited as long as it is a lithium cobalt oxide or a transition metal oxide containing at least Ni and Co, with 50 mol % or more of the transition metals being Ni and Co, and capable of electrochemically absorbing and desorbing metal ions, but for example, a material capable of electrochemically absorbing and desorbing lithium ions is preferred, and a transition metal oxide containing lithium and at least Ni and Co, with 60 mol % or more of the transition metals being Ni and Co, is preferred. This is because Ni and Co have oxidation-reduction potentials suitable for use as positive electrode materials in secondary batteries and are suitable for high-capacity applications.

[0129] Among these, a preferred embodiment is a transition metal oxide represented by the following composition formula (11). Li a1 Ni b1 Co c1 M d1 O2···(11) In the above formula (11), a1, b1, c1, and d1 represent numerical values ​​within the range of 0.90≦a1≦1.10, 0.50≦b1≦0.98, 0.01≦c1<0.50, and 0.01≦d1<0.50, and satisfy b1+c1+d1=1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er. In the composition formula (11), it is preferable that the value d1 satisfies 0.1≦d1<0.5. By setting the composition ratios of Ni and Co and other metal species within the above ranges, there are advantages in that transition metals are less likely to leach out of the positive electrode, and even if they do leach out, Ni and Co have little adverse effect on the non-aqueous secondary battery. A suitable example is LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, Li 1.05 Ni 0.50 Co 0.20 Mn 0.30 O2, LiNi 0.6 Co 0.2 Mn0.2 O2 or LiNi 0.8 Co 0.1 Mn 0.1 Examples include O2.

[0130] <2-4. Negative electrode> The negative electrode refers to a current collector having a negative electrode active material on at least a portion of the surface of the current collector. The other components may be those conventionally known.

[0131] The negative electrode active material is not particularly limited as long as it can electrochemically absorb and release metal ions. Specific examples include carbon-based materials, materials containing metal elements and / or metalloid elements that can be alloyed with Li, lithium-containing metal composite oxide materials, and mixtures thereof. These materials may be used alone or in any combination of two or more. From the viewpoints of good cycle characteristics, safety, and excellent continuous charge characteristics, it is preferable to use a carbon-based material, metal particles that can be alloyed with Li, and a mixture of a material containing a metal element and / or metalloid element that can be alloyed with Li and graphite particles.

[0132] Examples of carbonaceous materials include natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite. Of these, natural graphite is preferred.

[0133] Examples of natural graphite include scaly graphite, scaly graphite, and / or graphite particles obtained by treating such graphite as a raw material with treatments such as spheroidization and densification. Among these, spherical or ellipsoidal graphite particles that have been subjected to a spheroidization treatment are particularly preferred from the viewpoints of particle packing properties and charge / discharge rate characteristics. The average particle size (d50) of the graphite particles is usually 1 μm or more and usually 100 μm or less.

[0134] As a material containing a metal element and / or a metalloid element that can be alloyed with Li, any conventionally known material can be used. However, from the viewpoints of capacity and cycle life, the metal particles are preferably a material containing a metal element and / or a metalloid element selected from the group consisting of, for example, Sb, Si, Sn, Al, As, and Zn. Further, when the material containing a metal element and / or a metalloid element that can be alloyed with Li contains two or more metal elements and / or metalloid elements, the material may be a material composed of an alloy of these metal elements and / or metalloid elements. In addition, examples of the material containing a metal element and / or a metalloid element that can be alloyed with Li include metal oxides, metal nitrides, metal carbides, or Si-containing inorganic compounds. The compound may contain two or more materials containing a metal element and / or a metalloid element that can be alloyed with Li. Among them, metallic Si (hereinafter sometimes referred to as Si) or a Si-containing inorganic compound is preferable in terms of achieving a high capacity. In addition, the material containing a metal element and / or a metalloid element that can be alloyed with Li may already be alloyed with Li during the production of the negative electrode described later. Si or a Si-containing inorganic compound is preferable in terms of achieving a high capacity.

[0135] In this specification, Si or a Si-containing inorganic compound is collectively referred to as a Si compound. Specific examples of the Si compound include SiO x (0 ≦ x ≦ 2), etc. Specific examples of the material containing a metal element and / or a metalloid element that can be alloyed with Li include Li y Si (0 < y ≦ 4.4), Li 2z SiO 2+z (0 < z ≦ 2), etc. As the Si compound, a Si oxide (SiO x、 0 < x ≦ 2) is preferable in terms of having a larger theoretical capacity compared to graphite, or amorphous Si or nano-sized Si crystals are preferable in terms of allowing easy entry and exit of alkali ions such as lithium ions and enabling a high capacity to be obtained. The mixture of graphite particles and a material containing a metal element and / or a metalloid element that can be alloyed with Li, which is used as the negative electrode active material, may be a mixture in which the material containing a metal element and / or a metalloid element that can be alloyed with Li and the graphite particles are mixed in the form of particles that are independent of each other, or may be a composite in which the material containing a metal element and / or a metalloid element that can be alloyed with Li is present on the surface or inside of graphite particles. The content of the material containing a metal element and / or a metalloid element capable of being alloyed with Li relative to the total of the material containing a metal element and / or a metalloid element capable of being alloyed with Li and the graphite particles is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more, and is usually 99% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, still more preferably 25% by mass or less, even more preferably 20% by mass or less, particularly preferably 15% by mass or less, and most preferably 10% by mass or less.

[0136] <2-5. Separator> A separator is usually interposed between the positive electrode and the negative electrode to prevent short circuiting. In this case, the nonaqueous electrolyte solution according to one embodiment of the present invention is usually impregnated into the separator before use. Any conventional separator can be used. [Example]

[0137] 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.

[0138] The compounds used in the present examples and comparative examples are shown below.

[0139] Example 1

[0140] [ka]

[0141]

change

[0142]

change

[0143]

change

[0144]

change

[0145]

change

[0146]

change

[0147]

change

[0148]

change

[0149]

change

[0150]

change

[0151]

change

[0152] [ka]

[0153] [ka]

[0154] <Examples 1-1 to 1-17 and Comparative Examples 1-1 to 1-15> [Preparation of positive electrode] The positive electrode active material was lithium-nickel-cobalt-manganese composite oxide (Li 1.0 Ni 0.5 Co 0.2 Mn 0.3 90 parts by mass of O2), 7 parts by mass of acetylene black as a conductive material, and 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in N-methylpyrrolidone solvent using a disperser to form a slurry. This slurry was evenly applied to both sides of a 15 μm thick aluminum foil, dried, and then pressed to form a positive electrode.

[0155] [Preparation of negative electrode] To 98 parts by mass of natural graphite, 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 one side of a 10 μm-thick copper foil, dried, and then pressed to form a negative electrode.

[0156] [Preparation of non-aqueous electrolyte] Under a dry argon atmosphere, 1.2 mol / L (14.8 mass%, as the concentration in the non-aqueous electrolyte) of LiPF6 was dissolved as an electrolyte in a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) (volume ratio EC:DEC:EMC = 3:3:4). Furthermore, 2.0 mass% (as the concentration in the non-aqueous electrolyte) of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) were added (hereinafter referred to as reference electrolyte 1). Compounds 1-1 to 1-14 were added to reference electrolyte 1 in the amounts listed in Table 1 below to prepare the non-aqueous electrolytes of Examples 1-1 to 1-17 and Comparative Examples 1-2 to 1-15. The "content (mass%)" in the table is the content when the entire non-aqueous electrolyte is taken as 100 mass%. Furthermore, compound 8 is a compound having an Si—O bond, but does not fall under the category of compounds represented by formula (A).

[0157] [Manufacturing non-aqueous electrolyte 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 protruded. The prepared nonaqueous electrolyte solution was then poured into the bag, which was then vacuum-sealed to prepare a laminated nonaqueous electrolyte battery.

[0158] <Evaluation of non-aqueous electrolyte batteries> [Initial conditioning] The battery was charged at a constant current of 0.05 C for 6 hours in a 25°C thermostatic chamber, then discharged at 0.2 C to 3.0 V. CC-CV charging was performed at 0.2 C to 4.1 V. Aging was then performed at 45°C for 72 hours. The battery was then discharged at 0.2 C to 3.0 V to stabilize the laminated battery. CC-CV charging was then performed at 0.2 C to 4.2 V, followed by discharging at 0.2 C to 3.0 V for initial conditioning. [Measurement of gas volume generated during initial conditioning] After the initial conditioning, the battery was immersed in an ethanol bath and the volume was measured. The amount of gas generated was calculated from the change in volume before and after the initial conditioning, and this was taken as the "initial gas amount."

[0159] [Charged storage test] After initial conditioning, the non-aqueous electrolyte battery was again CC-CV charged at 0.2 C to 4.2 V, and then stored at high temperature at 60°C for two weeks. After that, the non-aqueous electrolyte battery was allowed to cool sufficiently, and then immersed in an ethanol bath to measure the volume. The amount of gas generated was calculated from the change in volume before and after the storage test, and this was taken as the "storage gas amount."

[0160] [Initial resistance] After initial conditioning, the batteries were CC-CV charged at 0.2 C to half the initial discharge capacity. They were then discharged at 1.0 C, 2.0 C, and 3.0 C at 25°C, and the voltage was measured after 5 seconds. The average slope of the current-voltage curves at 1.0 C, 2.0 C, and 3.0 C was taken as the initial resistance. Table 1 below shows the initial gas amount and stored gas amount when the initial gas amount and stored gas amount of Comparative Example 1-1 are set to 100, and the initial resistance when the initial resistance of Comparative Example 1-1 is set to 100.

[0161] [Table 1]

[0162] Comparison of Comparative Examples 1-2 to 1-9 and 1-13 to 1-15 with Comparative Example 1-1 reveals that when a nonaqueous electrolyte solution containing only either a compound having an Si-O structure represented by general formula (A) or general formula (B) or a specific unsaturated silane compound is used, there is a tendency for the amount of initial gas and storage gas generated in the nonaqueous electrolyte battery to increase, as well as for the initial resistance to increase. Examples 1-1 to 1-17 show that the amount of initial gas generation, the amount of gas generation during storage, and the increase in initial resistance can be significantly suppressed by combining the compounds represented by general formula (A), general formula (B), and general formula (α). When these compounds are used alone, the characteristics deteriorate, so it is clear that the combination provides a unique effect. Furthermore, from Comparative Example 1-10, it can be seen that when a compound having an Si-O structure but not corresponding to the compound having an Si-O structure represented by general formula (A) or general formula (B) was used, the amount of initial gas and storage gas generated increased. Furthermore, when comparing Comparative Examples 1-11 and 1-12 with Examples 1-1, 1-3 and 1-5, it can be seen that when a compound that does not fall under the category of unsaturated silane compounds represented by general formula (α) is used, storage gas is suppressed more than in Comparative Example 1-1, but is suppressed more in the Examples, and the amount of initial gas generated and the initial resistance value are higher in the Comparative Examples than in the Examples. As is clear from Table 1, the nonaqueous electrolyte solution containing the compound having an Si-O structure represented by general formula (A) or general formula (B) according to one embodiment of the present invention and the specific unsaturated silane compound can suitably suppress the generation of initial gas and storage gas in a nonaqueous electrolyte battery, and can also suppress an increase in the initial resistance of the battery.

[0163] <Example 2> 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.

[0164] The compounds used in the present examples and comparative examples are shown below.

[0165] [ka]

[0166] [ka]

[0167] [ka]

[0168] [ka]

[0169] [ka]

[0170] [ka]

[0171] [ka]

[0172] <Examples 2-1 to 2-6, Comparative Examples 2-1 to 2-8> [Preparation of positive electrode] The positive electrode active material was lithium-nickel-cobalt-manganese composite oxide (Li 1.0 Ni 0.5 Co 0.2 Mn 0.3 90 parts by mass of O2), 7 parts by mass of acetylene black as a conductive material, and 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder were mixed in N-methylpyrrolidone solvent using a disperser to form a slurry. This slurry was evenly applied to both sides of a 15 μm thick aluminum foil, dried, and then pressed to form a positive electrode.

[0173] [Preparation of negative electrode] To 98 parts by mass of natural graphite, 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 one side of a 10 μm-thick copper foil, dried, and then pressed to form a negative electrode.

[0174] [Preparation of non-aqueous electrolyte] Under a dry argon atmosphere, 1.2 mol / L (14.8 mass%, as the concentration in the non-aqueous electrolyte) of thoroughly dried LiPF6 was dissolved as an electrolyte in a mixture of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) (volume ratio EC:DEC:EMC = 3:3:4). Furthermore, 2.0 mass% each of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) (as the concentration in the non-aqueous electrolyte) was added (hereinafter referred to as reference electrolyte 1). Compounds 2-1 to 2-7 were added to reference electrolyte 1 in the amounts listed in Table 1 below to prepare the non-aqueous electrolytes of Examples 2-1 to 2-6 and Comparative Examples 2-2 to 2-8. Reference electrolyte 1 itself was used as the non-aqueous electrolyte in Comparative Example 1. The "content (mass%)" in the table refers to the content when the entire non-aqueous electrolyte is taken as 100 mass%.

[0175] [Manufacturing non-aqueous electrolyte 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, with the positive and negative electrode terminals protruding, and the prepared nonaqueous electrolyte solution was then poured into the bag, which was then vacuum-sealed to prepare a laminated nonaqueous electrolyte battery.

[0176] <Evaluation of non-aqueous electrolyte batteries> [Initial conditioning] The battery was charged at a constant current of 0.05 C for 6 hours in a 25°C thermostatic chamber, then discharged at 0.2 C to 3.0 V. CC-CV charging was performed at 0.2 C to 4.1 V. Aging was then performed at 45°C for 72 hours. The battery was then discharged at 0.2 C to 3.0 V to stabilize the laminated battery. CC-CV charging was then performed at 0.2 C to 4.2 V, followed by discharging at 0.2 C to 3.0 V for initial conditioning. [Measurement of gas volume generated during initial conditioning] After the initial conditioning, the battery was immersed in an ethanol bath and the volume was measured. The amount of gas generated was calculated from the change in volume before and after the initial conditioning, and this was taken as the "initial gas amount." [Initial resistance] After initial conditioning, the batteries were CC-CV charged at 0.2 C to half the initial discharge capacity. They were then discharged at 1.0 C, 2.0 C, and 3.0 C at 25°C, and the voltage was measured after 5 seconds. The average slope of the current-voltage curves at 1.0 C, 2.0 C, and 3.0 C was taken as the initial resistance. Table 2 below shows the initial gas amount when the initial gas amount of Comparative Example 2-1 is set to 100, and the initial resistance when the initial resistance is set to 100.

[0177] [Table 2]

[0178] It can be seen from Table 2 that the batteries produced in Examples 2-1 to 2-6 had smaller initial gas amounts and lower initial resistances than the batteries produced in Comparative Examples 2-1 to 2-8. Comparison of Comparative Example 2-1 with Comparative Examples 2-2, 2-5, and 2-6 reveals that when a nonaqueous electrolyte solution containing only a compound having a B-O structure represented by formula (C) without containing a silicon compound represented by formula (α) is used, the initial gas amount tends to be larger than that of Comparative Example 2-1. Furthermore, comparison of Comparative Example 2-1 with Comparative Examples 2-3 to 2-4 reveals that when a nonaqueous electrolyte solution containing only a silicon compound represented by formula (α) without containing a compound having a B-O structure represented by formula (C) is used, the initial gas amount tends to be larger than that of Comparative Example 2-1. From these results, it is expected that the use of a nonaqueous electrolyte solution containing a compound having a BO structure represented by formula (C) and a silicon compound represented by formula (α) would increase the amount of initial gas in the battery. However, the amount of initial gas in Examples 2-1 to 2-6 was reduced, which can be said to be an unexpectedly significant effect. In Comparative Examples 2-7 and 2-8, in which a compound having a BO structure represented by formula (C) was used in combination with a compound not corresponding to the compound represented by formula (α), the initial gas amount in Comparative Example 2-7 increased by 69% compared to Comparative Example 2-1, and the initial resistance also increased by 21% compared to Comparative Example 2-1. In Comparative Example 2-8, although the initial gas amount was improved compared to Comparative Example 2-1, the gas suppression effect was inferior to that of the Examples, and the initial resistance increased by 9% compared to Comparative Example 2-1. Furthermore, when Examples 2-1 and 2-2 are compared with Examples 2-3, 2-4, 2-5, and 2-6, it is found that, among the compounds having the BO structure represented by formula (C), Compound 2-3, which is a boron-containing cyclic compound, has a superior initial gas suppression effect to Compounds 2-4 and 2-5, which are boron-containing chain compounds. Comparing Examples 2-3 and 2-4 with Examples 2-5 and 2-6, it is clear that among boron-containing chain compounds, Compound 2-5, which has three alkylsilyl groups, has a better initial gas suppression effect than Compound 2-4, which is a compound having three halogen-substituted alkyl groups. In the batteries of the examples, after the electrolyte injection, the silicon compound represented by general formula (α) and the compound having a BO structure represented by general formula (C) are adsorbed in large amounts to the positive electrode active material and / or the negative electrode active material. This is presumably because the compounds localized on the electrodes are electrochemically decomposed during the first charge to form a composite insulating coating on the surface of the positive electrode active material and / or the negative electrode active material. Thus, by combining a compound having a structure represented by general formula (α) with a compound having a BO structure represented by general formula (C), it is possible to control the adsorption of the compound onto the electrode and to suitably suppress the generation of initial gas.

Claims

1. A nonaqueous electrolyte solution for a nonaqueous electrolyte battery having a positive electrode and a negative electrode capable of absorbing and releasing metal ions, the nonaqueous electrolyte solution containing, together with an alkali metal salt and a nonaqueous solvent, at least one compound selected from a compound represented by general formula (A), a compound represented by general formula (B), a compound represented by general formula (C″), and triethanolamine borate, and also containing a compound represented by general formula (α). 【Chemical 1】 (In formula (A), R １ ~R ６ each independently represents a hydrocarbon group having 1 to 4 carbon atoms which may have a substituent, and n represents an integer of 1 or 2. 【Chemistry 2】 (In formula (B), R ７ ~R ８ each independently represents a hydrocarbon group having 1 to 4 carbon atoms which may have a substituent, and k represents an integer of 3 or 4. 【Chemistry 3】 (In general formula (C"), R 1a' to R 3a' each independently represent a hydrocarbon group having 1 to 10 carbon atoms which may have a heteroatom, or a trialkylsilyl group which may have a substituent, and at least one of them is a hydrocarbon group having 1 to 10 carbon atoms which may have a heteroatom, or a trialkylsilyl group which may have a substituent.) 【Chemistry 4】 (In formula (α), R ９ ~R １１ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aralkyl group having 7 to 18 carbon atoms, which may have a substituent; and Y represents an alkenyl group or alkynyl group having 2 to 10 carbon atoms, which may have a substituent.

2. The total content of at least one compound selected from the group consisting of the compound represented by the general formula (A), the compound represented by the general formula (B), the compound represented by the general formula (C″), and triethanolamine borate is 1.0 × 10 relative to the total amount of the nonaqueous electrolyte solution. －３ The nonaqueous electrolyte solution according to claim 1 , wherein the content of the nonaqueous electrolyte is from 1% by mass to 10% by mass.

3. The nonaqueous electrolyte solution according to claim 1 or 2, wherein the content of the compound represented by general formula (α) is 0.01 mass ppm or more and 0.5 mass % or less with respect to the total amount of the nonaqueous electrolyte solution.

4. a ratio of the total content of at least one compound selected from the compound represented by general formula (A), the compound represented by general formula (B), the compound represented by general formula (C″), and triethanolamine borate to the content of the compound represented by general formula (α) in the nonaqueous electrolyte solution is 1.0 or more and 1.0 × 10 ４ The non-aqueous electrolyte solution according to any one of claims 1 to 3, wherein:

5. The R １ ~R ６ and R ７ ~R ８ 5. The nonaqueous electrolyte solution according to claim 1, wherein at least one of the groups is a hydrocarbon group having 2 to 4 carbon atoms and a carbon-carbon unsaturated bond.

6. 6. The nonaqueous electrolyte solution according to claim 1, wherein Y is an alkenyl group having 2 to 10 carbon atoms which may have a substituent.

7. In the formula (A), R 1 to R 6 each independently represent a hydrocarbon group having 1 to 4 carbon atoms, and n represents an integer of 1 or 2. In the formula (B), R 7 to R 8 each independently represent a hydrocarbon group having 1 to 4 carbon atoms, and k represents an integer of 3 or 4. In the formula (C″), R 1a′ to R 3a′ each independently represent a hydrocarbon group having 1 to 4 carbon atoms which may have a heteroatom, or a trialkylsilyl group, and at least one of them is a hydrocarbon group having 1 to 4 carbon atoms which may have a heteroatom, or a trialkylsilyl group. The non-aqueous electrolyte solution according to any one of claims 1 to 6.

8. The nonaqueous electrolyte solution according to any one of claims 1 to 7, wherein the compound represented by general formula (C'') is tristrimethylsilyl borate.

9. A non-aqueous electrolyte battery comprising a positive electrode and a negative electrode capable of absorbing and releasing metal ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is the non-aqueous electrolyte solution according to any one of claims 1 to 8.

Images