Non-aqueous electrolyte solution, non-aqueous electrolyte secondary battery, and compound

Abstract

To provide a non-aqueous electrolyte solution capable of reducing the rate of increase in internal resistance during high-temperature storage when used in a non-aqueous electrolyte battery.SOLUTION: A non-aqueous electrolyte solution comprises an electrolyte, a non-aqueous solvent, and a compound represented by general formula (I). The electrolyte contains at least one specific anion-containing compound selected from the group consisting of: anion-containing compounds having a P=O bond and a P-F bond; anion-containing compounds having an S=O bond and an S-X bond (X: heteroatom); and oxalate anion-containing compounds.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a non-aqueous electrolyte, a non-aqueous electrolyte secondary battery containing the non-aqueous electrolyte, and a compound. [Background technology]

[0002] 2. Description of the Related Art Non-aqueous electrolyte secondary batteries, such as lithium ion 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 notebook computers, and on-board power sources for driving electric vehicles and the like. As a means for improving the battery characteristics of non-aqueous electrolyte secondary batteries, many studies have been conducted in the fields of positive and negative electrode active materials and additives for non-aqueous electrolytes.

[0003] In recent years, lithium ion batteries have been used as non-aqueous electrolyte secondary batteries in applications such as on-board power sources for electric vehicles and power sources for mobile phones such as smartphones. Lithium ion batteries have been rapidly increasing in capacity for the above applications, and the proportion of voids in the battery has become smaller than before. Therefore, an increase in internal resistance during charging and discharging of lithium ion batteries is a fatal drawback. In general, battery deterioration accelerates in high-temperature environments, and internal resistance tends to increase, so it is very important to suppress the rate of increase.

[0004] In view of this, Patent Document 1 discloses a study on improving various characteristics such as post-storage characteristics and cycle capacity retention rate by adding a specific compound to a non-aqueous electrolyte solution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2003 / 077350 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the nonaqueous electrolyte secondary battery using the nonaqueous electrolyte described in Patent Document 1 has room for improvement in terms of suppressing the rate of increase in internal resistance during high-temperature storage.

[0007] An object of the present invention is to provide a nonaqueous electrolyte solution capable of suppressing the rate of increase in internal resistance during high-temperature storage when used in a nonaqueous electrolyte battery, a nonaqueous electrolyte secondary battery using the nonaqueous electrolyte solution, and a novel compound that can be contained in the nonaqueous electrolyte solution. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors conducted intensive research to solve the above problems and discovered that by adding a specific silicon-containing sulfonate ester compound and a specific anion-containing compound to a non-aqueous electrolyte solution, the rate of increase in internal resistance during high-temperature storage can be suppressed when the non-aqueous electrolyte solution is used in a non-aqueous electrolyte battery, and thus completed the present invention.

[0009] That is, the gist of the present invention relates to the following [1] to

[12] . [1] An electrolyte, a non-aqueous solvent, and a compound represented by general formula (I), The electrolyte is a non-aqueous electrolyte solution characterized in that it contains at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a PF bond, an anion-containing compound having an S=O bond and an SX bond (X: heteroatom), and an oxalate anion-containing compound.

[0010] [ka]

[0011] (In general formula (I), R 1 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 2 and R 3 each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R4 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, and n represents an integer of 1 to 4.

[0012] [2] In the general formula (I), R 2 and R 3 and are both hydrogen atoms. [3] The nonaqueous electrolyte solution according to [1] or [2] above, wherein in the general formula (I), n is 1 or 2. [4] In the general formula (I), R 4 The nonaqueous electrolyte solution according to any one of the above [1] to [3], wherein is a methyl group. [5] The nonaqueous electrolyte solution according to any one of the above [1] to [4], wherein the specific anion-containing compound is an anion-containing compound having the P=O bond and the PF bond. [6] The non-aqueous electrolyte solution according to any one of [1] to [5] above, wherein the content of the compound represented by general formula (I) in the non-aqueous electrolyte solution is 0.001 to 10 mass %. [7] The nonaqueous electrolyte solution according to any one of [1] to [6], wherein a mass ratio of the content of the compound represented by general formula (I) to the content of the specific anion-containing compound is 0.01 or more and 100 or less. [8] The nonaqueous electrolyte solution according to any one of [1] to [7], wherein the content of the specific anion-containing compound in the nonaqueous electrolyte solution is 0.001 to 5 mass %.

[0013] [9] A non-aqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of absorbing and releasing metal ions, and a non-aqueous electrolyte, A non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of [1] to [8] above.

[10] The nonaqueous electrolyte secondary battery according to [9], wherein the positive electrode contains a positive electrode active material, and the positive electrode active material is a lithium transition metal compound.

[0014]

[11] A compound represented by the following general formula (II):

[0015] [ka]

[0016] (In general formula (II), R 21 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 22 and R 23 each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 24 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, n 2 represents an integer from 2 to 4.)

[0017]

[12] A compound represented by the following formula (A2-1):

[0018] [ka] Effect of the Invention

[0019] According to the non-aqueous electrolyte of the present invention, the internal resistance increase rate during high-temperature storage can be suppressed. Therefore, a non-aqueous electrolyte secondary battery in which the internal resistance increase rate during high-temperature storage is suitably suppressed can be provided. In addition, by using the compound of the present invention, the above-mentioned excellent non-aqueous electrolyte can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following describes in detail the embodiment of the present invention. However, the following description is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to these contents. Furthermore, the present invention can be modified as desired without departing from the gist of the present invention. In this specification, "α to β" means a numerical range of α or more and β or less.

[0021] <1.Non-aqueous electrolyte> The non-aqueous electrolyte according to the present embodiment contains an electrolyte, a non-aqueous solvent, and a compound represented by general formula (I). The electrolyte contains at least one specific anion-containing compound selected from an anion-containing compound having a P=O bond and a PF bond, an anion-containing compound having a S=O bond and a SX bond (X: heteroatom), and an oxalate anion-containing compound. Each component will be described below.

[0022] [1-1. Compound represented by general formula (I)]

[0023] [ka]

[0024] (In general formula (I), R 1 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 2 and R 3 each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 4 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, and n represents an integer of 1 to 4.

[0025] [R 1 〕 R 1 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom. When n in general formula (I) is 2 to 4, a plurality of R 1 may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same.

[0026] Above R 1 Specific examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, of which a fluorine atom and a chlorine atom are preferred, and a fluorine atom is particularly preferred. The halogen atom is preferred because it tends to suppress side reactions of the compound represented by general formula (I) on the surface of the electrode active material.

[0027] Above R 1 Specific examples of the hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and a halogenated hydrocarbon group in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with halogen atoms. Specific examples and preferred examples of the halogen atom are as shown in the above R 1 is the same as the specific examples when is a halogen atom.

[0028] Above R 1 Specific examples of the alkyl group having 1 to 10 carbon atoms include linear alkyl groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups; branched alkyl groups such as i-propyl, methylpropyl, t-butyl, methylbutyl, methylpentyl, methylhexyl, methylheptyl, methyloctyl, and methylnonyl groups; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclohexylmethyl, cyclohexylethyl, methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, and methylcyclohexylmethyl groups. Among the above alkyl groups, a linear alkyl group or a branched alkyl group is preferred, and a linear alkyl group is more preferred. Among them, an alkyl group having 1 to 10 carbon atoms is preferred from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material, and among them, an alkyl group having 1 to 6 carbon atoms is more preferred, an alkyl group having 1 to 4 carbon atoms is even more preferred, a methyl group or an ethyl group is even more preferred, and a methyl group is most preferred.

[0029] Above R 1The alkenyl group having 1 to 10 carbon atoms is substantially an alkenyl group having 2 to 10 carbon atoms, but is preferred from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material. Specific examples thereof include alkenyl groups having 2 to 10 carbon atoms such as vinyl group, allyl group, isopropenyl group, methallyl group, 2-butenyl group, 3-methyl-2-butenyl group, 3-butenyl group, or 4-pentenyl group, and linear alkenyl groups are preferred. Among them, more preferred are alkenyl groups having 2 to 6 carbon atoms such as vinyl group, allyl group, methallyl group, or 2-butenyl group, further more preferred are alkenyl groups having 2 to 4 carbon atoms such as vinyl group, allyl group, or methallyl group, and particularly preferred are vinyl group or allyl group.

[0030] Above R 1 The alkynyl group having 1 to 10 carbon atoms is substantially an alkynyl group having 2 to 10 carbon atoms, but is preferred from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material. Specific examples thereof include alkynyl groups having 2 to 10 carbon atoms such as ethynyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group, 4-pentynyl group, and 5-hexynyl group, and linear alkynyl groups are preferred. Among them, more preferred are alkynyl groups having 2 to 6 carbon atoms such as ethynyl group, 2-propynyl group, 2-butynyl group, and 3-butynyl group, further more preferred are alkynyl groups having 2 to 4 carbon atoms such as 2-propynyl group and 3-butynyl group, and particularly preferred is 2-propynyl group.

[0031] Above R 1 The aryl group having 1 to 10 carbon atoms, which is substantially an aryl group having 6 to 10 carbon atoms, is preferred from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material. Specific examples thereof include aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a tolyl group, or a mesityl group. Among them, aryl groups having 6 to 7 carbon atoms, such as a phenyl group or a tolyl group, are preferred, and a phenyl group is particularly preferred.

[0032] Above R 1The halogenated hydrocarbon group means that the hydrocarbon group is substituted with a halogen atom. The halogenated hydrocarbon group is preferable from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material. Specific examples thereof include those in which a part or all of the hydrogen atoms of each of the hydrocarbon groups exemplified as the alkyl group, alkenyl group, alkynyl group, and aryl group having 1 to 10 carbon atoms are substituted with a halogen atom. More specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, a 4-fluorobutyl group, a 5-fluoropentyl group, a 6-fluorohexyl group, a 2-fluorophenyl group, a pentafluorophenyl group, and the like. Among them, a halogenated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, and a 4-fluorobutyl group is preferable, and a fluorinated alkyl group having 1 to 4 carbon atoms is more preferable. Furthermore, halogenated alkyl groups having 1 or 2 carbon atoms, such as a trifluoromethyl group or a 2,2,2-trifluoroethyl group, are more preferred, and fluorinated alkyl groups having 1 or 2 carbon atoms are even more preferred. Of these, a trifluoromethyl group is even more preferred.

[0033] The above mentioned R 1 Among these, from the viewpoint that the compound represented by general formula (I) is suitably concentrated on the surface of the electrode active material and the reactivity of the compound represented by general formula (I) with the specific anion-containing compound tends to be suitably controlled, it is preferably a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom, more preferably a hydrocarbon group having 1 to 10 carbon atoms which is not substituted with a halogen atom, even more preferably an alkyl group having 1 to 10 carbon atoms, even more preferably an alkyl group having 1 to 4 carbon atoms, particularly preferably a methyl group or an ethyl group, and most preferably a methyl group.

[0034] [R 2 and R 3 〕 R in general formula (I) 2 and R 3each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom. When n in general formula (I) is 2 to 4, 2 and R 3 may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same.

[0035] R 2 and R 3 Specific and preferred examples of the halogen atom and the hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom are the same as those of the above R 1 and a hydrocarbon group having 1 to 10 carbon atoms which may be substituted by a halogen atom, respectively, and this is because there is a tendency that the reactivity between the compound represented by general formula (I) and the specific anion-containing compound is suitably controlled.

[0036] Among them, R 2 and R 3 are each preferably independently a hydrogen atom or a halogen atom, and R 2 and R 3 Most preferably, both are hydrogen atoms.

[0037] [R 4 〕 R in general formula (I) 4 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom. When n in the general formula (I) is 1 or 2, a plurality of R 4 may be the same or different, but from the viewpoint of ease of production, they are preferably the same. 4 does not exist.

[0038] Above R 4 Specific examples of the alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom include an alkyl group and a halogenated alkyl group in which some or all of the hydrogen atoms of the alkyl group are substituted with halogen atoms. Specific examples and preferred examples of the halogen atom are the above-mentioned R 1The specific and preferred examples of the halogen atom are the same as those given above.

[0039] R 4 Specific and preferred examples of R 1 are the same as the specific and preferred examples given above when is an alkyl group having 1 to 10 carbon atoms.

[0040] R 4 Specific examples of the halogenated alkyl group having 1 to 10 carbon atoms include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, a 4-fluorobutyl group, a 5-fluoropentyl group, and a 6-fluorohexyl group. Among the above, from the viewpoint that the compound represented by the general formula (I) tends to be suitably concentrated on the surface of the electrode active material, a halogenated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3-fluoropropyl group, and a 4-fluorobutyl group is preferred, and a fluorinated alkyl group having 1 to 4 carbon atoms is more preferred. Furthermore, a halogenated alkyl group having 1 or 2 carbon atoms such as a trifluoromethyl group and a 2,2,2-trifluoroethyl group is more preferred, and a fluorinated alkyl group having 1 or 2 carbon atoms is even more preferred. Among them, a trifluoromethyl group is even more preferred.

[0041] The above mentioned R 4 Among these, from the viewpoint that the reactivity of the compound represented by general formula (I) with the specific anion-containing compound tends to be suitably controlled, it is more preferably a halogen-atom-unsubstituted alkyl group having 1 to 10 carbon atoms, even more preferably an alkyl group having 1 to 4 carbon atoms, still more preferably a methyl group or an ethyl group, and most preferably a methyl group.

[0042] [n] In general formula (I), n represents an integer of 1 to 4. From the viewpoint of suitably controlling the density of the composite coating film composed of the compound represented by general formula (I) and the specific anion-containing compound, n is preferably 1 or 2.

[0043] [Specific examples] R in general formula (I) 1 ~R 4 The combination of and n is arbitrary, but for example, R 1 is a methyl group, R 2 and R 3 are both hydrogen atoms, R 4 is a methyl group, and n is preferably 1 or 2, more preferably 2 or more, even more preferably 3 or more, and particularly preferably all of the above. 2 and R 3 are both hydrogen atoms, R 4 It is particularly preferable that all of the following conditions are satisfied: is a methyl group; and n is 1 or 2.

[0044] Specific examples of the compound represented by general formula (I) include compounds represented by the following formulas (A1-1) to (A1-20) (hereinafter referred to as compounds (A1-1) to (A1-20)), compounds represented by the following formulas (A2-1) to (A2-20) (hereinafter referred to as compounds (A2-1) to (A2-20)), and compounds represented by the following formulas (A3-1) and (A4-1) (hereinafter referred to as compounds (A3-1) and (A4-1)). The compounds represented by general formula (I) are not particularly limited to the following examples.

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] Among the above compounds, the compound represented by the general formula (I) is suitably concentrated on the surface of the electrode active material, the compound represented by the general formula (I) and the specific anion-containing compound suitably react to form a composite coating, and the density of the composite coating is suitably controlled. From this viewpoint, R 2 and R 3 are preferably both hydrogen atoms, and the compounds (A1-1) to (A1-16), (A2-1) to (A2-16), (A3-1), and (A4-1) are preferred. R 2 and R 3 is a hydrogen atom, and n is 1 or 2. Compounds (A1-1) to (A1-16) and compounds (A2-1) to (A2-16) are more preferred. 2 and R 3 is a hydrogen atom, n is 1 or 2, and R 4 More preferred are compounds (A1-1) to (A1-13) and compounds (A2-1) to (A2-13) in which R 2 and R 3 is a hydrogen atom, n is 1 or 2, and R 4 is a methyl group, and R 1 is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom, and 2 and R 3 is a hydrogen atom, n is 1 or 2, and R 4 is a methyl group, and R 1 The most preferred are the compounds (A1-1) to (A1-4) and the compounds (A2-1) to (A2-4), in which is an alkyl group having 1 to 10 carbon atoms.

[0051] The mechanism by which the nonaqueous electrolyte according to this embodiment can suppress the rate of increase in internal resistance during high-temperature storage in a charged state is not clear, but is thought to be as follows. The compound represented by the general formula (I) is Si-C-OSO2R 1 The compound represented by general formula (I) has a skeleton. In this skeleton, the reaction activity of the compound represented by general formula (I) is increased by the interaction between the σ bond of the Si-C bond and the unshared electron pair of the O atom linked to the C atom. This allows the compound represented by general formula (I) to react favorably with a specific anion-containing compound, and form a favorable composite coating on the surface of the electrode active material. It is believed that the composite coating suppresses the decomposition of the solvent on the surface of the electrode active material, thereby contributing to a reduction in the rate of increase in internal resistance.

[0052] The content of the compound represented by the general formula (I) in the non-aqueous electrolyte 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, from the viewpoint that the concentration of the compound represented by the general formula (I) on the active material on the surface of the electrode active material proceeds suitably and a battery with a smaller internal resistance increase rate during high-temperature storage can be produced. Also, it is usually 10% by mass or less, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. In addition, the content of the compound represented by the general formula (I) is usually 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 0.1% by mass or more and 3.0% by mass or less, more preferably 0.2% by mass or more and 2.0% by mass or less, and even more preferably 0.2% by mass or more and 1.0% by mass or less.

[0053] There is no particular limitation on the method for incorporating the compound represented by general formula (I) in the non-aqueous electrolyte solution. However, a method in which the compound represented by general formula (I) is added to a non-aqueous solvent or the like, or a method in which a raw material for the compound represented by general formula (I) is added to a non-aqueous solvent or the like to generate the compound represented by general formula (I) are also preferred. The compound represented by general formula (I) can be identified and its content can be measured by nuclear magnetic resonance (NMR) spectroscopy, gas chromatography mass spectrometry (GC / MS), or the like.

[0054] The compound represented by the above general formula (I) can be produced by the following method. The production method of the compound represented by the general formula (I) is not particularly limited to the following examples. For example, there is a method in which an alcohol having a hydroxyl group at the α-position of a silicon atom, such as trimerylsilylmethanol, is reacted with an alkylsulfonyl chloride, such as methanesulfonyl chloride; and a method in which an alkyl halide having a halogen at the α-position of a silicon atom, such as (chloromethyl)trimethylsilane, is reacted with an alkylsulfonate, such as silver methanesulfonate.

[0055] [Compound represented by general formula (II)] Among the compounds represented by general formula (I), the compound represented by the following general formula (II) is a novel compound and is another embodiment of the present invention.

[0056] [ka]

[0057] (In general formula (II), R 21 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 22 and R 23 each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R 24 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, n 2 represents an integer from 2 to 4.)

[0058] [R 21 〕 R in general formula (II) 21 represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom. 21 may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same. 21 Specific and preferred examples of R 1These are the same as the specific examples and preferred examples shown in

[0059] [R 22 and R 23 〕 R in general formula (II) 22 and R 23 represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom. 22 and R 23 may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same. 22 and R 23 Specific and preferred examples of R 2 and R 3 These are the same as the specific examples and preferred examples shown in

[0060] [R 24 〕 R in general formula (II) 24 represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom. 2 If is 2 or 3, there are multiple R 24 may be the same or different, but from the viewpoint of ease of production, it is preferable that they are the same. 24 Specific and preferred examples of R 4 These are the same as the specific examples and preferred examples shown in

[0061] [n 2 〕 In general formula (II), n 2 represents an integer from 2 to 4. 2 is preferably 2.

[0062] [Specific examples] R in general formula (II) 21 ~R 24 and n 2 The combination of is arbitrary. For example, R 21 is a methyl group, R 22 and R 23are both hydrogen atoms, R 24 is a methyl group, and n 2 It is preferable that one or more of the following two conditions are satisfied, more preferable that two or more conditions are satisfied, further preferable that three or more conditions are satisfied, and particularly preferable that all of the following conditions are satisfied. 22 and R 23 are both hydrogen atoms, R 24 is a methyl group, and n 2 It is particularly preferable that all of the above conditions are satisfied.

[0063] Specific examples of the compound represented by general formula (II) include compounds represented by the following formulas (A2-1) to (A2-20) (hereinafter referred to as compounds (A2-1) to (A2-20)) and compounds represented by the following formulas (A3-1) and (A4-1) (hereinafter referred to as compounds (A3-1) and (A4-1)). The compound represented by general formula (II) is not particularly limited to the following examples.

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] Among the above compounds, R 22 and R 23 are both hydrogen atoms, and the compounds (A2-1) to (A2-16), (A3-1) and (A4-1) are preferred. 22 and R 23 are both hydrogen atoms, and n 2 More preferred are compounds (A2-1) to (A2-16) in which R 22 and R 23 are both hydrogen atoms, and n 2 is 2 and R24 is a methyl group, and the compounds (A2-1) to (A2-13) are more preferred. 22 and R 23 are both hydrogen atoms, and n 2 is 2 and R 24 is a methyl group, and R 21 is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom, and 22 and R 23 are both hydrogen atoms, and n 2 is 2 and R 24 is a methyl group, and R 21 Particularly preferred are compounds (A2-1) to (A2-4) in which is an alkyl group having 1 to 10 carbon atoms. Of these, compound (A2-1) is the most preferred.

[0068] Examples of uses of the compound represented by general formula (II) are given below, but the uses of the compound represented by general formula (II) are not particularly limited to the following examples. The compound represented by the general formula (II) can be used as an additive to non-aqueous electrolyte in the battery field to suppress the internal resistance increase rate of non-aqueous electrolyte batteries. It can also be used as a coating agent or surface modifier in the fields of electronic materials, biocompatible materials, and functional materials. It can also be used as an alkylating agent to introduce a silicon skeleton in the organic synthetic chemistry field to be used as a raw material or intermediate for pharmaceuticals, pesticides, dyes, and surfactants.

[0069] [1-2. Electrolytes] The electrolyte of the non-aqueous electrolyte is preferably an alkali metal salt such as lithium, sodium, or potassium. When the non-aqueous electrolyte according to the present embodiment is used in a lithium ion battery, the counter cation in the electrolyte is preferably a lithium cation. When the non-aqueous electrolyte according to the present embodiment is used in a sodium ion battery, the counter cation in the electrolyte is preferably a sodium ion. When the non-aqueous electrolyte according to the present embodiment is used in a potassium ion battery, the counter cation in the electrolyte is preferably a potassium ion.

[0070] The electrolyte content in the nonaqueous electrolyte according to this embodiment is usually more than 5% by mass, and is classified into a "main salt" that is mainly responsible for ion conduction, and an "auxiliary agent" whose content is 5% by mass or less. The electrolyte in the nonaqueous electrolyte according to this embodiment preferably contains a specific anion-containing compound as an auxiliary agent in addition to the main salt. Therefore, the content of the specific anion-containing compound in the nonaqueous electrolyte is preferably 5% by mass or less.

[0071] [1-2-1. Main salt] The electrolyte in the non-aqueous electrolyte according to the present embodiment preferably contains a compound other than the compound shown in [1-2-2. Specific anion-containing compound] as a main salt. The other compound that serves as the electrolyte varies depending on the type of secondary battery to which the non-aqueous electrolyte is applied, but preferably includes, for example, a lithium salt, and also preferably includes a sodium salt or a potassium salt.

[0072] The lithium salt is not particularly limited, and examples thereof include lithium fluoroborates, lithium fluorophosphates, lithium tungstates, lithium carboxylates, lithium sulfonates, lithium imide salts, lithium methide salts, lithium oxalate salts, and fluorine-containing organic lithium salts.

[0073] Among these, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc., the following are used: LiBF4 as lithium fluoroborate salt; LiPF6, Li2PO3F, LiPO2F2 as lithium fluorophosphate salt; LiFSO3, CH3SO3Li as lithium sulfonate salt; LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium cyclic 1,2-perfluoroethane disulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, etc. Sulfonylimides; lithium methide salts such as LiC(FSO2)3, LiC(CF3SO2)3, and LiC(C2F5SO2)3; and lithium oxalate salts such as lithium difluorooxalatoborate, lithium bis(oxalato)borate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate are preferred, with one or more selected from LiPF6, LiN(FSO2)2, lithium bis(oxalato)borate, and LiFSO3 being more preferred, and LiPF6 being particularly preferred.

[0074] The other compounds which become the electrolyte can be used either individually or in combination of two or more kinds in any ratio. The combination of two or more types of other compounds that can be used as the electrolyte is not particularly limited, and examples thereof include a combination of LiPF6 and LiN(FSO2)2, a combination of LiPF6 and LiBF4, a combination of LiPF6 and LiN(CF3SO2)2, a combination of LiBF4 and LiN(FSO2)2, and a combination of LiBF4, LiPF6 and LiN(FSO2)2. Among these, the combination of LiPF6 and LiN(FSO2)2, the combination of LiPF6 and LiBF4, and the combination of LiBF4, LiPF6 and LiN(FSO2)2 are preferred.

[0075] The sodium salt is not particularly limited, and examples thereof include sodium fluoroborates, sodium fluorophosphates, sodium tungstates, sodium carboxylates, sodium sulfonates, sodium imide salts, sodium methide salts, sodium oxalate salts, and fluorine-containing organic sodium salts.

[0076] Among these, from the viewpoint of improving low-temperature output characteristics, high-rate charge / discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc., the following are used: sodium fluoroborate salt: NaBF4; sodium fluorophosphate salt: NaPF6, Na2PO3F, NaPO2F2; sodium sulfonate salt: NaFSO3, CH3SO3Na; sodium imide salt: NaN(FSO2)2, NaN(FSO2)(CF3SO2), NaN(CF3SO2)2, NaN(C2F5SO2)2, sodium cyclic 1,2-perfluoroethane disulfonylimide, sodium cyclic 1,3-perfluoropropane disulfonylimide, Sulfonylimides; as sodium methide salts, NaC(FSO2)3, NaC(CF3SO2)3, NaC(C2F5SO2)3; as sodium oxalate salts, sodium difluorooxalatoborate, sodium bis(oxalato)borate, sodium tetrafluorooxalate phosphate, sodium difluorobis(oxalato)phosphate, sodium tris(oxalato)phosphate, etc. are preferred, with one or more selected from NaPF6, NaN(FSO2)2, sodium bis(oxalato)borate and NaFSO3 being more preferred, with NaPF6 being particularly preferred.

[0077] The other compounds which become the electrolyte can be used either individually or in combination of two or more kinds in any ratio. Combinations of other compounds that form two or more types of electrolytes are not particularly limited, and examples include a combination of NaPF6 and NaN(FSO2)2, a combination of NaPF6 and NaBF4, a combination of NaPF6 and NaN(CF3SO2)2, a combination of NaBF4 and NaN(FSO2)2, and a combination of NaBF4, NaPF6 and NaN(FSO2)2. Among these, a combination of NaPF6 and NaN(FSO2)2, a combination of NaPF6 and NaBF4, and a combination of NaBF4, NaPF6 and NaN(FSO2)2 are preferred.

[0078] Examples of potassium salts include those in which Li and Na in the above lithium salts and sodium salts are substituted with potassium (K).

[0079] The total content of the electrolyte in this embodiment is not particularly limited, but from the viewpoint of making the electric conductivity appropriate for the battery operation and exhibiting sufficient output characteristics, it is usually 8 mass% or more, preferably 8.5 mass% or more, more preferably 9 mass% or more, and usually 18 mass% or less, preferably 17 mass% or less, more preferably 16 mass% or less, based on the total amount of the nonaqueous electrolyte. The content of the electrolyte is usually 8 mass% or more and 18 mass% or less, preferably 8.5 mass% or more and 17 mass% or less, more preferably 9 mass% or more and 16 mass% or less, based on the total amount of the nonaqueous electrolyte. However, the content of the compound shown in [1-2-2. Specific anion-containing compound] below is also included in the content of the electrolyte. In addition, when a compound corresponding to [1-4. Auxiliary agent] described below is contained in the non-aqueous electrolyte, an electrolyte other than the lithium salt corresponding to the auxiliary agent is necessarily contained. The electrolytes are identified and their content is measured by nuclear magnetic resonance (NMR) spectroscopy.

[0080] [1-2-2. Compounds containing specific anions] The electrolyte in the nonaqueous electrolyte according to the present embodiment contains a specific anion-containing compound, which is at least one compound selected from the group consisting of an anion-containing compound having a P=O bond and a PF bond, an anion-containing compound having a S=O bond and an SX bond (X: heteroatom), and an oxalate anion-containing compound.

[0081] The specific anion-containing compound is usually an acid or a salt, and is preferably a salt. The counter cation in the specific anion-containing compound is preferably an alkali metal cation such as lithium, sodium, or potassium, and more preferably a lithium cation. In addition, when the nonaqueous electrolyte according to the present embodiment is used in a lithium ion battery, the counter cation is preferably a lithium cation; when the nonaqueous electrolyte according to the present embodiment is used in a sodium ion battery, the counter cation is preferably a sodium ion; and when the nonaqueous electrolyte according to the present embodiment is used in a potassium ion battery, the counter cation is preferably a potassium ion.

[0082] The method of adding the specific anion-containing compound to the non-aqueous electrolyte is not particularly limited, but includes a method of adding a salt of the specific anion-containing compound, preferably a method of adding one or more selected from the group consisting of lithium salt, sodium salt, and potassium salt of the specific anion-containing compound, more preferably a method of adding a lithium salt of the specific anion-containing compound. Also, a method of adding a raw material of the specific anion-containing compound to the electrolyte to generate the specific anion-containing compound in the electrolyte is also preferred.

[0083] At least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P=O bond and a PF bond, an anion-containing compound having an S=O bond and an SX bond (X: heteroatom), and an oxalate anion-containing compound can be used alone or in combination of two or more in any ratio.

[0084] Among these, from the viewpoint of suppressing the rate of increase in internal resistance after high-temperature storage, anion-containing compounds having a PF bond and a P=O bond, and anion-containing compounds having an S=O bond and an SX bond are preferred, and anion-containing compounds having a PF bond and a P=O bond are particularly preferred.

[0085] [1-2-3. Anion-containing compounds with PF bonds and P=O bonds] An example of the specific anion-containing compound having a PF bond and a P=O bond in this embodiment is PO3F 2- Monofluorophosphate anion, such as PO2F2 - and the like. Among these, compounds containing difluorophosphate anions are preferred from the viewpoint of the balance between the output characteristics of the battery and the protection of the electrode interface.

[0086] The method of adding an anion-containing compound having a PF bond and a P=O bond to an electrolyte is not particularly limited, but includes a method of adding a salt of an anion-containing compound having a PF bond and a P=O bond, and a method of adding one or more selected from lithium monofluorophosphate, lithium difluorophosphate, sodium monofluorophosphate, sodium difluorophosphate, potassium monofluorophosphate, and potassium difluorophosphate is preferred, and a method of adding at least one of lithium monofluorophosphate and lithium difluorophosphate is more preferred. Also preferred is a method of adding a raw material of an anion-containing compound having a PF bond and a P=O bond to an electrolyte to generate an anion-containing compound having a PF bond and a P=O bond in the electrolyte.

[0087] [1-2-4. Anion-containing compounds with S=O and SX bonds] In the anion-containing compound having an S=O bond and an SX bond, which is one aspect of the specific anion-containing compound in this embodiment, X represents a heteroatom. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, and a fluorine atom. Specific examples of the anion-containing compound having an S=O bond and an SX bond include, for example, FSO3 - Fluorosulfonate anion such as (FSO2)2N - , (FSO2)(CF3SO2)N - Fluorosulfonylimide anions such as (FSO2)3C - Compounds containing fluorosulfonylmethide anion such as CH3SO4 - , C2H5SO4 - Examples of the compound include compounds containing alkyl sulfate anions such as those mentioned above. Among these, from the viewpoint of the balance between the output characteristics of the battery and the protection of the electrode interface, compounds containing a fluorosulfonate anion, a fluorosulfonylimide anion, and an alkyl sulfate anion are preferred, compounds containing a fluorosulfonate anion or a fluorosulfonylimide anion are more preferred, and compounds containing a fluorosulfonate anion are even more preferred.

[0088] There is no particular limitation on the method of adding an anion-containing compound having an S=O bond and an SX bond to the electrolyte, but examples include a method of adding a salt of an anion-containing compound having an S=O bond and an SX bond, and a method of adding one or more selected from lithium fluorosulfonate, lithium fluorosulfonylimide, sodium fluorosulfonate, sodium fluorosulfonylimide, potassium fluorosulfonate, potassium fluorosulfonylimide, lithium methylsulfate, lithium ethylsulfate, sodium methylsulfate, sodium ethylsulfate, potassium methylsulfate, and potassium ethylsulfate is preferred, and a method of adding one or more selected from lithium fluorosulfonate, lithium fluorosulfonylimide, lithium methylsulfate, and lithium ethylsulfate is more preferred. Also preferred is a method of adding a raw material of an anion-containing compound having an S=O bond and an SX bond to the electrolyte and generating an anion-containing compound having an S=O bond and an SX bond in the electrolyte.

[0089] [1-2-5. Compounds containing oxalate complex anions] The oxalate complex anion-containing compound, which is one aspect of the specific anion-containing compound in the present embodiment, is not particularly limited as long as it is a compound that contains an anion having an oxalate complex in the molecule.The oxalate complex anion-containing compound is a compound that contains an anion of an acid that forms a complex by coordinating or bonding with oxalic acid to a central atom, and can be exemplified by a compound that contains a boron oxalate complex anion in which oxalic acid is coordinated or bonded to a boron atom, and a phosphorus oxalate complex anion in which oxalic acid is coordinated or bonded to a phosphorus atom.

[0090] Examples of the boron oxalato complex anion include a bis(oxalato)borate anion and a difluorooxalatoborate anion. Examples of the phosphorus oxalate complex anion include a tetrafluorooxalate phosphate anion, a difluorobis(oxalate)phosphate anion, and a tris(oxalate)phosphate anion. Among these, from the viewpoint of forming a stable composite coating on the surface of the electrode, a compound containing a boron oxalate complex anion is preferred, and a compound containing a bis(oxalate)borate anion is more preferred.

[0091] The method of adding the oxalate complex anion-containing compound to the electrolyte is not particularly limited, and examples thereof include a method of adding a salt of the oxalate complex anion-containing compound, such as lithium bis(oxalate)borate, lithium difluorooxalate borate, lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate)phosphate, lithium tris(oxalate)phosphate, sodium bis(oxalate)borate, sodium difluorooxalate borate, sodium tetrafluorooxalate phosphate, sodium difluorobis(oxalate)phosphate, sodium tris ... A method of adding one or more selected from potassium bis(oxalate)borate, potassium difluorooxalateborate, potassium tetrafluorooxalatephosphate, potassium difluorobis(oxalate)phosphate, and potassium tris(oxalate)phosphate is preferred, and a method of adding one or more selected from lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium tetrafluorooxalatephosphate, lithium difluorobis(oxalate)phosphate, and lithium tris(oxalate)phosphate is more preferred. Also preferred is a method of adding a raw material of an oxalate complex anion-containing compound to an electrolyte to generate an oxalate complex anion-containing compound in the electrolyte.

[0092] [Content of specific anion-containing compound] The content of the specific anion-containing compound in the non-aqueous electrolyte according to this embodiment is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and also preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of significantly improving the battery characteristics, particularly the direct current resistance (DCR) retention rate after high-temperature storage, and significantly suppressing the internal resistance increase rate after high-temperature storage. The content of the specific anion-containing compound is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 4% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less. In addition, when two or more specific anion-containing compounds are contained, the content means the total content of them.

[0093] The non-aqueous electrolyte according to the present embodiment contains a specific anion-containing compound, which improves the battery characteristics, particularly the DCR retention rate after high-temperature storage, and suppresses the internal resistance increase rate after high-temperature storage. Although the reason for this is unclear, the specific anion-containing compound can minimize the side reaction of the components of the non-aqueous electrolyte on the electrode surface, and it is believed that this effect is more favorably achieved within the range of the content of the specific anion-containing compound. The identification and content of specific anion-containing compounds are carried out by nuclear magnetic resonance (NMR) spectroscopy, ion chromatography (IC), or the like.

[0094] [Mass ratio of the compound represented by formula (I) to the specific anion-containing compound] The mass ratio of the content of the compound represented by general formula (I) to the content of the specific anion-containing compound, i.e., the mass ratio represented by the compound represented by general formula (I) [g] / specific anion-containing compound [g], is usually 0.01 or more, preferably 0.02 or more, more preferably 0.03 or more, even more preferably 0.04 or more, even more preferably 0.05 or more, particularly preferably 0.1 or more, even more preferably 0.3 or more, even more preferably 0.6 or more, and particularly preferably 0.7 or more, from the viewpoint of suppressing the internal resistance increase rate during high-temperature charged storage, and is usually 100 or less, preferably 30 or less, more preferably 25 or less, even more preferably 15 or less, especially preferably 11 or less, even more preferably 10 or less, even more preferably 8 or less, even more preferably 5 or less, even more preferably 4 or less, even more preferably 3 or less, and particularly preferably 2.5 or less. The mass ratio is usually 0.01 to 100, preferably 0.02 to 30, more preferably 0.03 to 25, even more preferably 0.04 to 15, even more preferably 0.05 to 11, especially preferably 0.1 to 10, still more preferably 0.3 to 8, even more preferably 0.6 to 5, even more preferably 0.7 to 4, even more preferably 0.7 to 3, and particularly preferably 0.7 to 2.5. The content of the compound represented by the general formula (I) and the specific anion-containing compound means the total content when two or more of them are contained.

[0095] If the mass ratio is within the above range, the battery characteristics, particularly the DCR retention rate after high-temperature storage, can be significantly improved, and the internal resistance increase rate after high-temperature storage can be significantly suppressed. Although the reason for this is unclear, it is believed that by containing the compound represented by general formula (I) and the specific anion-containing compound within the above mass ratio range, the side reaction of the components of the nonaqueous electrolyte on the electrode surface can be minimized.

[0096] [Mass ratio of specific anion-containing compound to main salt] The electrolyte in the non-aqueous electrolyte according to the present embodiment contains the specific anion-containing compound, but the mass ratio of the content of the specific anion-containing compound to the content of the main salt constituting the electrolyte, i.e., the mass ratio expressed as the specific anion-containing compound [g] / main salt [g], is usually 0.00005 or more, preferably 0.0005 or more, more preferably 0.001 or more, even more preferably 0.005 or more, even more preferably 0.01 or more, particularly preferably 0.015 or more, and is usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, even more preferably 0.35 or less. The mass ratio is usually 0.00005 or more and 0.5 or less, preferably 0.0005 or more and 0.5 or less, more preferably 0.001 or more and 0.45 or less, even more preferably 0.005 or more and 0.4 or less, even more preferably 0.01 or more and 0.35 or less, particularly preferably 0.015 or more and 0.35 or less. When two or more specific anion-containing compounds are contained, the content of the specific anion-containing compound refers to the total content thereof.

[0097] When the mass ratio is within the above range, the battery characteristics, particularly the DCR retention rate after high-temperature storage, can be significantly improved, and the internal resistance increase rate after high-temperature storage can be significantly suppressed. Although the reason for this is unclear, it is believed that by containing a specific anion-containing compound and a main salt within the above mass ratio range, side reactions of the electrolyte in the battery system can be minimized.

[0098] [1-3. Non-aqueous solvents] The non-aqueous electrolyte solution according to this embodiment contains a non-aqueous solvent. The non-aqueous solvent is a component that dissolves the above-mentioned electrolyte.

[0099] There are no particular limitations on the non-aqueous solvent, and any known organic solvent can be used. Examples of the organic solvent include saturated cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; chain carboxylic acid esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone; ether compounds such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane; and sulfone compounds such as 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, dimethylsulfone, ethylmethylsulfone, and monofluoromethylmethylsulfone. Among these, saturated cyclic carbonates, chain carbonates, and chain or cyclic carboxylic acid esters are preferred, and saturated cyclic carbonates and chain carbonates are more preferred. These non-aqueous solvents can be used alone or in combination of two or more.

[0100] The combination of two or more non-aqueous solvents is not particularly limited, and examples thereof include saturated cyclic carbonates and chain carboxylates, cyclic carboxylates and chain carbonates, and saturated cyclic carbonates, chain carbonates and chain carboxylates. Among these, the combinations of saturated cyclic carbonates and chain carbonates, and saturated cyclic carbonates, chain carbonates and chain carboxylates are preferred.

[0101] [1-3-1. Saturated cyclic carbonates] The saturated cyclic carbonate, which is one embodiment of the non-aqueous solvent in this embodiment, typically has an alkylene group having 2 to 4 carbon atoms, and from the viewpoint of improving the battery characteristics resulting from the improvement of the degree of dissociation of lithium ions, saturated cyclic carbonates having 2 to 3 carbon atoms are preferably used.

[0102] Examples of the saturated cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, etc. Among them, ethylene carbonate and propylene carbonate are preferred, and ethylene carbonate, which is less susceptible to oxidation and reduction, is more preferred. The saturated cyclic carbonate may be used alone or in any combination and ratio of two or more kinds.

[0103] The content of the saturated cyclic carbonate is not particularly limited and may be any content as long as it does not significantly impair the effects of the present invention, but is usually 3 to 90% by volume, preferably 3 to 85% by volume, and more preferably 5 to 80% by volume, based on the total amount of the nonaqueous solvent in the nonaqueous electrolyte. Here, the content is usually 3% by volume or more, preferably 5% by volume or more, while it is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting it in this range, the decrease in electrical conductivity due to the decrease in the dielectric constant of the nonaqueous electrolyte is avoided, and the large current discharge characteristics, stability to the negative electrode, and cycle characteristics of the nonaqueous electrolyte secondary battery are easily in a good range, and the oxidation / reduction resistance of the nonaqueous electrolyte is improved, and the stability during high-temperature storage tends to be improved. In the present embodiment, the volume % refers to the volume at 25° C. and 1 atmospheric pressure.

[0104] [1-3-2. Chain carbonate] As the chain carbonate, which is one aspect of the non-aqueous solvent in this embodiment, one having 3 to 7 carbon atoms is usually used, and in order to adjust the viscosity of the electrolyte solution within an appropriate range, a chain carbonate having 3 to 5 carbon atoms is preferably used.

[0105] Specific examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethyl methyl carbonate, and methyl-n-propyl carbonate. Dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are particularly preferred.

[0106] In addition, chain carbonates having fluorine atoms (hereinafter, sometimes abbreviated as "fluorinated chain carbonate") can also be suitably used. The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, and preferably 4 or less. When the fluorinated chain carbonate has multiple fluorine atoms, they may be bonded to the same carbon or different carbons.

[0107] Examples of the fluorinated chain carbonate include fluorinated dimethyl carbonate derivatives such as fluoromethyl methyl carbonate, fluorinated ethyl methyl carbonate derivatives such as 2-fluoroethyl methyl carbonate, and fluorinated diethyl carbonate derivatives such as ethyl-(2-fluoroethyl) carbonate.

[0108] The chain carbonate may be used alone or as a mixture of two or more kinds in any combination and in any ratio.

[0109] The content of the chain carbonate is not particularly limited, but is usually 15 to 90 volume %, preferably 20 to 85 volume %, and more preferably 25 to 80 volume % relative to the total amount of the nonaqueous solvent in the nonaqueous electrolyte. Here, the content is usually 15 volume % or more, preferably 20 volume % or more, more preferably 25 volume % or more, and is usually 90 volume % or less, preferably 85 volume % or less, and more preferably 80 volume % or less. By setting the content of the chain carbonate in the above range, the viscosity of the nonaqueous electrolyte can be set in an appropriate range, the decrease in ion conductivity can be suppressed, and the output characteristics of the nonaqueous electrolyte secondary battery can be easily set in a good range.

[0110] Furthermore, by combining a specific chain carbonate with ethylene carbonate in a specific content, the battery performance can be significantly improved.

[0111] For example, when dimethyl carbonate and ethyl methyl carbonate are selected as the specific chain carbonate, the content of ethylene carbonate is not particularly limited and is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 15 to 45 volume %, preferably 20 to 40 volume %, based on the total amount of non-aqueous solvent in the non-aqueous electrolyte. Here, the content is usually 15 volume % or more, preferably 20 volume % or more, and usually 45 volume % or less, preferably 40 volume % or less. Furthermore, the content of dimethyl carbonate is usually 20 to 50 volume %, preferably 30 to 45 volume %, based on the total amount of non-aqueous solvent in the non-aqueous electrolyte. Here, the content is usually 20 volume % or more, preferably 30 volume % or more, and usually 50 volume % or less, preferably 45 volume % or less. Furthermore, the content of ethyl methyl carbonate is usually 20 to 50 volume %, preferably 30 to 45 volume %, based on the total amount of non-aqueous solvent in the non-aqueous electrolyte. Here, the content is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. By setting each content within the above range, high temperature stability is excellent and gas generation tends to be suppressed.

[0112] [1-3-3. Chain carboxylate esters] Examples of the chain carboxylate ester, which is one aspect of the non-aqueous solvent in this embodiment, include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, ethyl isobutyrate, and methyl pivalate. Among them, methyl acetate, ethyl acetate, propyl acetate, and butyl acetate are preferred from the viewpoint of improving battery characteristics. In addition, chain carboxylate esters in which a part of the hydrogen of each of the above-mentioned chain carboxylate esters is substituted with fluorine can also be suitably used. Examples of such chain carboxylate esters substituted with fluorine include methyl trifluoroacetate and ethyl trifluoroacetate.

[0113] [1-3-4. Cyclic carboxylate esters] Examples of the cyclic carboxylate ester, which is one aspect of the non-aqueous solvent in this embodiment, include γ-butyrolactone and γ-valerolactone. Among these, γ-butyrolactone is more preferable. Cyclic carboxylate esters in which a part of the hydrogen of each of the above-mentioned cyclic carboxylate esters is replaced with fluorine can also be used suitably.

[0114] [1-3-5. Ether compounds] Preferred examples of the ether compound, which is one aspect of the non-aqueous solvent in this embodiment, include chain ethers having 3 to 10 carbon atoms, such as dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether, and cyclic ethers having 3 to 6 carbon atoms, such as tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, and 1,4-dioxane.

[0115] Among these, as the chain ethers having 3 to 10 carbon atoms, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferred because they have a high solvation ability for lithium ions, improve ion dissociation, have low viscosity, and provide high ionic conductivity, and as the cyclic ethers having 3 to 6 carbon atoms, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, and the like are preferred because they provide high ionic conductivity.

[0116] The content of the ether-based compound is not particularly limited, and may be any content as long as it does not significantly impair the effects of the present invention according to this embodiment. However, it is usually 1 to 30% by volume, preferably 2 to 25% by volume, and more preferably 3 to 20% by volume, based on the total amount of the non-aqueous solvent. Here, the content is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, and more preferably 20% by volume or less. If the content of the ether-based compound is within the above range, it is easy to ensure the effect of improving the lithium ion dissociation degree of the ether and improving the ion conductivity due to the viscosity reduction. In addition, when the negative electrode active material is a carbon-based material, the phenomenon in which the chain ether is co-inserted with the lithium ion can be suppressed, so that the input / output characteristics and the charge / discharge rate characteristics can be set to appropriate ranges.

[0117] [1-3-6. Sulfone compounds] The sulfone compound, which is one aspect of the non-aqueous solvent in this embodiment, is not particularly limited and may be either a cyclic sulfone or a chain sulfone, but in the case of a cyclic sulfone, the carbon number is usually 3 to 6, preferably 3 to 5. In addition, in the case of a chain sulfone, the carbon number is usually 2 to 6, preferably 2 to 5. In addition, the number of sulfonyl groups in one molecule of the sulfone compound is not particularly limited, but is usually 1 or 2.

[0118] Examples of cyclic sulfones include monosulfone compounds such as trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones; and disulfone compounds such as trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferred, and tetramethylene sulfones (sulfolanes) are particularly preferred.

[0119] The sulfolane is preferably sulfolane and / or a sulfolane derivative (hereinafter, sulfolane may be abbreviated as "sulfolane") The sulfolane derivative is preferably one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group.

[0120] Among these, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane, and the like are preferred because they have high ionic conductivity and high input / output.

[0121] Examples of the chain sulfone include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, monofluoromethyl methyl sulfone, difluoromethyl methyl sulfone, trifluoromethyl methyl sulfone, pentafluoroethyl methyl sulfone, etc. Among these, dimethyl sulfone, ethyl methyl sulfone, and monofluoromethyl methyl sulfone are preferred in terms of improving the high-temperature storage stability of the electrolyte.

[0122] The content of the sulfone-based compound is not particularly limited and may be any as long as it does not significantly impair the effects of the present invention according to this embodiment, but is usually 0.3 to 40 volume %, preferably 0.5 to 35 volume %, and more preferably 1 to 30 volume % based on the total amount of the non-aqueous solvent in the non-aqueous electrolyte. Here, the content is usually 0.3 volume % or more, preferably 0.5 volume % or more, more preferably 1 volume % or more, and is usually 40 volume % or less, preferably 35 volume % or less, and more preferably 30 volume % or less. If the content of the sulfone-based compound is within the above range, an electrolyte with excellent high-temperature storage stability tends to be obtained.

[0123] [1-4. Auxiliaries] The non-aqueous electrolyte according to the present embodiment may contain various auxiliary agents within the range that does not impair the effects of the present invention. As the auxiliary agent, any conventionally known one may be used. The auxiliary agent may be used alone or in combination of two or more kinds at any ratio.

[0124] Examples of the auxiliary include cyclic carbonates having a carbon-carbon unsaturated bond, fluorine-containing cyclic carbonates, compounds having an isocyanate group, compounds having an isocyanuric acid skeleton, sulfur-containing organic compounds, phosphorus-containing organic compounds, silicon-containing compounds, aromatic compounds, organic compounds having a cyano group, fluorine-free carboxylic acid esters, cyclic ether compounds, acid anhydrides, triple bond-containing compounds, phosphazene compounds, etc. For example, compounds described in International Publication No. 2015 / 111676 can be mentioned.

[0125] Among these, at least one carbonate compound selected from the group consisting of cyclic carbonates having a carbon-carbon unsaturated bond and fluorine-containing cyclic carbonates (hereinafter also referred to as "specific carbonate compound") is preferable.

[0126] The content of the auxiliary is not particularly limited, and is arbitrary 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 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably less than 1% by mass. The content of the auxiliary is usually 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, even more preferably 0.1% by mass or more and 1% by mass or less, and particularly preferably 0.1% by mass or more and 1% by mass or less, based on the total amount of the nonaqueous electrolyte.

[0127] Here, the cyclic ether compound can be used as an auxiliary in the non-aqueous electrolyte solution, and also includes those that can be used as a non-aqueous solvent as described in the section [1-3. Non-aqueous solvent]. When a cyclic ether compound is used as an auxiliary agent, it is used in an amount of 5 mass % or less, and preferably less than 4 mass %, based on the total amount of the nonaqueous electrolyte.

[0128] In addition, borate anion-containing compounds, oxalate complex anion-containing compounds, monofluorophosphate anion-containing compounds, and difluorophosphate anion-containing compounds can be used as auxiliary agents in nonaqueous electrolyte solutions, and also include those that can be used as electrolytes as described in the section [1-2. Electrolyte]. When these compounds are used as auxiliary agents, they are preferably used in an amount of less than 3 mass% based on the total amount of the nonaqueous electrolyte solution.

[0129] [1-4-1. Specific carbonate compounds] As described above, the non-aqueous electrolyte according to the present embodiment preferably contains at least one carbonate compound selected from the group consisting of cyclic carbonates having carbon-carbon unsaturated bonds and cyclic carbonates having fluorine atoms as an auxiliary. Among these, it is preferable to contain a cyclic carbonate having carbon-carbon unsaturated bonds, and it is more preferable to contain vinylene carbonate. These can be used alone or in combination of two or more in any ratio.

[0130] When two or more specific carbonate compounds are used in combination, it is preferable to combine an unsaturated cyclic carbonate with a fluorinated cyclic carbonate, it is more preferable to combine vinylene carbonate with a fluorinated cyclic carbonate, and it is even more preferable to combine an unsaturated cyclic carbonate with monofluoroethylene carbonate, and it is even more preferable to combine vinylene carbonate with monofluoroethylene carbonate.

[0131] [Content of specific carbonate compounds] The content of the specific carbonate compound in the total amount of the non-aqueous electrolyte according to this embodiment 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 0.5% by mass or more, and is usually 10% by mass or less, preferably 6% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less. The content of the specific carbonate compound in the total amount of the non-aqueous electrolyte is usually 0.001% by mass or more and 10% by mass or less, preferably 0.01% by mass or more and 6% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 4% by mass or less. In addition, when two or more specific carbonate compounds are contained, the above content means the total content thereof. If the content of the specific carbonate compound is within the above range, the battery characteristics, particularly the durability, can be improved. Although the reason for this is unclear, it is believed that the inclusion of the specific carbonate compound at this ratio forms a coating on the electrode, minimizing the side reaction of the components of the non-aqueous electrolyte. The identification and content of specific carbonate compounds is determined by nuclear magnetic resonance (NMR) spectroscopy.

[0132] [Mass ratio of specific carbonate compound to compound represented by general formula (I)] In this embodiment, the mass ratio of the content of the specific carbonate compound to the content of the compound represented by general formula (I), i.e., the mass ratio represented by the specific carbonate compound [g] / compound represented by general formula (I) [g], is usually 0.01 or more, preferably 0.05 or more, more preferably 0.3 or more, and even more preferably 0.5 or more, and is usually 100 or less, preferably 10 or less, more preferably 5 or less, and even more preferably 4 or less. The mass ratio is usually 0.01 or more and 100 or less, preferably 0.05 or more and 10 or less, more preferably 0.3 or more and 5 or less, and even more preferably 0.5 or more and 4 or less. In addition, when the compound represented by general formula (I) and the specific carbonate compound each contain two or more kinds, the above content means the total content thereof. If the mass ratio is within the above range, the battery characteristics, especially the durability, can be improved. Although the reason for this is unclear, it is believed that by containing the specific carbonate compound and the compound represented by general formula (I) within the above range of mass ratio, a coating is formed on the electrode, and the side reaction of the components of the non-aqueous electrolyte can be minimized.

[0133] [Mass ratio of specific carbonate compound to main salt] In the non-aqueous electrolyte according to the present embodiment, the mass ratio of the content of the specific carbonate compound to the total content of the main salt constituting the electrolyte, that is, the mass ratio represented by the specific carbonate compound [g] / main salt [g], is usually 0.00005 or more, preferably 0.0005 or more, more preferably 0.001 or more, even more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.025 or more, and is usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, and even more preferably 0.35 or less. The mass ratio is usually 0.00005 or more and 0.5 or less, preferably 0.0005 or more and 0.5 or more, more preferably 0.001 or more and 0.45 or less, even more preferably 0.01 or more and 0.4 or less, even more preferably 0.02 or more and 0.35 or less, and especially preferably 0.025 or more and 0.35 or less. In addition, when two or more types of main salts and specific carbonate compounds are contained, the above content means the total content of each of them. If the mass ratio is within the above range, the battery characteristics, particularly the durability, can be improved. Although the reason for this is unclear, it is believed that by containing a specific carbonate compound and a main salt within the above range of mass ratio, a coating is formed on the electrode, and side reactions of the electrolyte in the battery system are minimized.

[0134] [1-4-1-1. Cyclic carbonates having carbon-carbon unsaturated bonds] The cyclic carbonate having carbon-carbon unsaturated bond (hereinafter also referred to as "unsaturated cyclic carbonate"), which is one aspect of the specific carbonate compound in this embodiment, is not particularly limited as long as it is a cyclic carbonate having carbon-carbon double bond or carbon-carbon triple bond. Cyclic carbonate having aromatic ring is also included in the unsaturated cyclic carbonate.

[0135] Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates, etc. Among these, vinylene carbonates and ethylene carbonates substituted with a substituent having an aromatic ring, a carbon-carbon double bond or a carbon-carbon triple bond are preferred.

[0136] Examples of vinylene carbonates include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinylvinylene carbonate, 4,5-vinylvinylene carbonate, allylvinylene carbonate, and 4,5-diallylvinylene carbonate.

[0137] Examples of ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4-allyl-5-vinyl ethylene carbonate, ethynyl ethylene carbonate, 4,5-diethynyl ethylene carbonate, 4-methyl-5-ethynyl ethylene carbonate, 4-vinyl-5-ethynyl ethylene carbonate, 4-allyl-5-ethynyl ethylene carbonate, phenyl ethylene carbonate, 4,5-diphenyl ethylene carbonate, 4-phenyl-5-vinyl ethylene carbonate, 4-allyl-5-phenyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, and 4-methyl-5-allyl ethylene carbonate. Among these, vinylene carbonate, vinyl ethylene carbonate, and ethynyl ethylene carbonate are preferred since they form a more stable composite coating on the electrode, and one or more selected from vinylene carbonate and vinyl ethylene carbonate are more preferred, with vinylene carbonate being even more preferred.

[0138] The unsaturated cyclic carbonates can be used alone or in combination of two or more kinds in any ratio.

[0139] [1-4-1-2. Cyclic carbonates containing fluorine atoms] The fluorine atom-containing cyclic carbonate, which is one embodiment of the specific carbonate compound in this embodiment, is not particularly limited as long as it has a cyclic carbonate structure and contains a fluorine atom.

[0140] Examples of cyclic carbonates having fluorine atoms include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof. More specifically, examples of such cyclic carbonates include fluorinated ethylene carbonate (fluoroethylene carbonate) and derivatives thereof, and ethylene carbonate having a fluorine-containing group.

[0141] Examples of the derivatives of fluorinated ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among these, fluoroethylene carbonate having 1 to 8 fluorine atoms and its derivatives are preferred.

[0142] Examples of fluoroethylene carbonate and derivatives thereof having 1 to 8 fluorine atoms, as well as ethylene carbonate having a fluorine-containing group, include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 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, from the viewpoints of imparting high ionic conductivity to the electrolyte and facilitating the formation of a stable interface protective film, one or more selected from monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are preferred.

[0143] The fluorine atom-containing cyclic carbonates can be used alone or in combination of two or more kinds in any ratio.

[0144] [1-4-2. Organic compounds containing isocyanate groups] The organic compound having an isocyanate group, which is one aspect of the auxiliary in the present embodiment, is not particularly limited as long as it is an organic compound having at least one isocyanate group in the molecule. The number of isocyanate groups in one molecule is preferably 1 to 4, more preferably 2 or 3, and even more preferably 2.

[0145] Examples of organic compounds having an isocyanate group include monoisocyanate compounds such as methyl isocyanate, ethyl isocyanate, butyl isocyanate, vinyl isocyanate, propargyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate; and diisocyanate compounds such as monomethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-diisocyanatopropane, 1,3-bis(isocyanatomethyl)cyclohexane, carbonyl diisocyanate, and 1,4-diisocyanato-2-fluorobutane. In particular, from the viewpoint of forming a stable interface protective coating, an organic compound having at least two isocyanate groups is preferred, hexamethylene diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane are more preferred, and 1,3-bis(isocyanatomethyl)cyclohexane is even more preferred.

[0146] [1-4-3. Organic compounds with an isocyanuric acid skeleton] The organic compound having an isocyanuric acid skeleton (hereinafter also referred to as "isocyanurate compound"), which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is an organic compound having at least one isocyanuric acid skeleton in the molecule. Examples of the organic compound having an isocyanuric acid skeleton include the following compounds.

[0147] [ka]

[0148] As the isocyanurate compound, particularly from the viewpoint of forming a stable interface protective coating, an isocyanurate compound having a saturated or unsaturated aliphatic hydrocarbon group which may have a halogen atom is preferred, an isocyanurate compound having an unsaturated aliphatic hydrocarbon group containing a carbon-carbon unsaturated bond at the terminal is more preferred, and triallyl isocyanurate is even more preferred.

[0149] [1-4-4. Sulfur-containing organic compounds] The sulfur-containing organic compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is an organic compound having at least one sulfur atom (S) in the molecule. Preferably, it is an organic compound having at least one S=O bond, and more preferably, an ester compound having an S=O bond such as a chain sulfonate ester, a cyclic sulfonate ester, a chain sulfate ester, a cyclic sulfate ester, a chain sulfite ester, and a cyclic sulfite ester. However, an anion-containing compound having an S=O bond and an SX bond is not a "sulfur-containing organic compound" but is included in the above "anion-containing compound having an S=O bond and an SX bond".

[0150] Examples of sulfur-containing organic compounds include methyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, busulfan, methyl methanesulfonyloxyacetate, methyl vinylsulfonate, allyl vinylsulfonate, propargyl allylsulfonate, methoxycarbonylmethyl methanedisulfonate, ethoxycarbonylmethyl methanedisulfonate, methoxycarbonylmethyl 1,3-butanedisulfonate, ethoxycarbonylmethyl 1,3-butanedisulfonate, 1-methoxycarbonylethyl 1,3-butanedisulfonate, and 1-ethoxycarbonyl 1,3-butanedisulfonate. Chain sulfonate esters such as alkyl disulfonate esters such as ethyl; 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 1-methyl-1,3-propane sultone, 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,5-pentane sultone, methylenemethane disulfonate, ethylenemethane disulfonate, 2,2-dioxide-1,2-oxathiolan-4-yl Cyclic sulfonate esters such as acetate; linear sulfate esters such as dimethyl sulfate, ethyl methyl sulfate, diethyl sulfate; cyclic sulfate esters such as 1,2-ethylene sulfate, 1,2-propylene sulfate, 1,3-propylene sulfate, 1,2-butylene sulfate; linear sulfite esters such as dimethyl sulfite, ethyl methyl sulfite, diethyl sulfite; cyclic sulfite esters such as 1,2-ethylene sulfite, 1,2-propylene sulfite, 1,3-propylene sulfite, 1,2-butylene sulfite; cyclic sulfones such as 1,1-dioxidetetrahydrothiophen-3-yl methanesulfonate and 1,1-dioxide-2,3-dihydrothiophen-3-yl methanesulfonate;Sulfonic acid esters such as butane-2,3-diyl dimethanesulfonate, butane-1,4-diyl dimethanesulfonate, or methylene methane disulfonate, and vinyl sulfone compounds such as divinyl sulfone, 1,2-bis(vinylsulfonyl)ethane, or bis(2-vinylsulfonylethyl)ether;

[0151] In particular, from the viewpoint of forming a stable interface protective coating, linear or cyclic sulfonate esters, cyclic sulfate esters, or cyclic sulfite esters are more preferred, cyclic sulfonate esters or cyclic sulfate esters are particularly preferred, and 1,3-propane sultone, methylenemethane disulfonate, and 1,2-ethylene sulfate are most preferred.

[0152] [1-4-5. Phosphorus-containing organic compounds] The phosphorus-containing organic compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is a compound having at least one phosphorus atom in the molecule. However, an anion-containing compound having a P=O bond and a PF bond is not a "phosphorus-containing organic compound" but is included in the above-mentioned "anion-containing compound having a P=O bond and a PF bond."

[0153] Examples of phosphorus-containing organic compounds include trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, ethyl 2-(diethoxyphosphoryl)acetate, and 2-propynyl 2-(diethoxyphosphoryl)acetate.

[0154] In particular, ethyl 2-(diethoxyphosphoryl)acetate or 2-propynyl 2-(diethoxyphosphoryl)acetate is preferred, with 2-propynyl 2-(diethoxyphosphoryl)acetate being more preferred.

[0155] [1-4-6. Silicon-containing compounds] The silicon-containing compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is a compound having at least one silicon atom in the molecule. Examples of silicon-containing compounds include boric acid compounds such as tris(trimethylsilyl) borate, tris(trimethoxysilyl) borate, tris(triethylsilyl) borate, and tris(dimethylvinylsilyl) borate; phosphate compounds such as tris(trimethylsilyl) phosphate, tris(triethylsilyl) phosphate, tris(triphenylsilyl) phosphate, tris(trimethoxysilyl) phosphate, and tris(dimethylvinylsilyl) phosphate; tris(trimethylsilyl) phosphite, tris(triethylsilyl) phosphite, tris(triphenylsilyl) phosphite, tris(trimethoxysilyl) phosphite, and tris(dimethylvinylsilyl) phosphite. sulfonic acid compounds such as trimethylsilyl methanesulfonate and trimethylsilyl tetrafluoromethanesulfonate; silane compounds such as tetramethylsilane, trimethylvinylsilane, dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane; disilane compounds such as hexamethyldisilane, hexaethyldisilane, 1,1,2,2-tetramethyldisilane, and 1,2-diphenyltetramethyldisilane; and disiloxane compounds such as hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, and 1,1,3,3-tetramethyl-1,3-diphenyldisiloxane.

[0156] In particular, from the viewpoint of forming a stable interface protective coating, disilane compounds and disiloxane compounds are preferred, disiloxane compounds are more preferred, hexamethyldisiloxane and 1,3-divinyltetramethyldisiloxane are even more preferred, and 1,3-divinyltetramethyldisiloxane is particularly preferred.

[0157] [1-4-7. Aromatic compounds] The aromatic compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is a compound having aromaticity in the molecule. Examples of the aromatic compound include aromatic compounds having branched alkyl groups such as cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, or 1-fluoro-4-tert-butylbenzene; aromatic compounds such as biphenyl, terphenyl (o-, m-, p-), fluorobenzene, methylphenyl carbonate, ethylphenyl carbonate, or diphenyl carbonate; and the like.

[0158] In particular, biphenyl, terphenyl (o-, m-, p-isomer), fluorobenzene, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene are more preferred, and biphenyl, o-terphenyl, fluorobenzene, cyclohexylbenzene, and tert-amylbenzene are more preferred.

[0159] [1-4-8. Organic compounds containing a cyano group] The organic compound having a cyano group, which is one embodiment of the auxiliary in this embodiment, is not particularly limited as long as it is an organic compound having at least one cyano group in the molecule. Examples of organic compounds having a cyano group include organic compounds having one cyano group in the molecule, such as acetonitrile, propionitrile, butyronitrile, pentanenitrile, hexanenitrile, decanenitrile, undecanenitrile, dodecanenitrile, cyclohexanecarbonitrile, acrylonitrile, methacrylonitrile, and crotononitrile; organic compounds having two cyano groups in the molecule, such as succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, sebaconitrile, methylmalononitrile, ethylmalononitrile, bicyclohexyl-1,1-dicarbonitrile, 1,4-dicyanopentane, and 1,2-dicyanobenzene; and organic compounds having three cyano groups in the molecule, such as 1,2,3-propanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,3,5-cyclohexanetricarbonitrile, and 1,3,5-benzenetricarbonitrile.

[0160] In particular, from the viewpoint of forming a stable interface protective film, an organic compound having two cyano groups is preferred, succinonitrile and adiponitrile are more preferred, and adiponitrile is even more preferred.

[0161] [1-4-9. Fluorine-free carboxylic acid esters] The fluorine-free carboxylate, which is one embodiment of the auxiliary in the present embodiment, is not particularly limited as long as it is a carboxylate that does not have a fluorine atom in the molecule. A fluorine-free chain carboxylic acid ester is preferable, and a fluorine-free saturated chain carboxylic acid ester is more preferable. The total number of carbon atoms of the fluorine-free chain carboxylate ester is preferably 3 to 7, more preferably 3 to 6, and even more preferably 4 to 5. Here, the total number of carbon atoms is preferably 3 or more, more preferably 4 or more, and preferably 7 or less, more preferably 6 or less, and even more preferably 5 or less.

[0162] Examples of the chain carboxylate ester include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, methyl pivalate, ethyl pivalate, n-propyl pivalate, isopropyl pivalate, n-butyl pivalate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, methyl crotonate, ethyl crotonate, and methyl 2-propionate. In particular, from the viewpoint of improving the output characteristics of the battery, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, and n-propyl propionate are preferred, with methyl propionate being more preferred.

[0163] [1-4-10. Cyclic ether compounds] The cyclic ether compound, which is one aspect of the auxiliary in the present embodiment, is not particularly limited as long as it is a compound having one or more ether bonds in the molecule. Examples of the cyclic ether compound include cyclic acetal compounds such as 1,3-dioxolane, 1,3-dioxane, and 1,3,5-trioxane.

[0164] As the cyclic ether compound, in particular, a cyclic acetal compound is preferable, 1,3-dioxolane or 1,3-dioxane is preferable, and 1,3-dioxane is more preferable.

[0165] [1-4-11. Acid anhydride] The acid anhydride, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is an acid anhydride having a “C(═O)—O—C(═O) group,” a “C(═O)—OS(═O) group,” or an “S(═O)—OS(═O) group” in the molecule. Examples of acid anhydrides include chain carboxylic acid anhydrides such as acetic anhydride, acrylic anhydride, methacrylic anhydride, cyclohexanecarboxylic anhydride, propynoic anhydride, benzoic anhydride, fluoroacetic anhydride, 4-fluorobenzoic anhydride, and acetic propionic anhydride, succinic anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, itaconic anhydride, fluorosuccinic anhydride, allylsuccinic anhydride, 1,2-oxathiolan-5-one 2,2-dioxide, and 1,2,6-oxadithiane 2,2,6,6-tetraoxide.

[0166] In particular, from the viewpoint of forming a stable interface protective film, methacrylic anhydride, succinic anhydride, maleic anhydride, and allylsuccinic anhydride are preferred, with succinic anhydride and allylsuccinic anhydride being more preferred.

[0167] [1-4-12. Triple bond-containing compounds] The triple bond-containing compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is a compound having at least one triple bond in the molecule.Examples of the triple bond-containing compound include 2-propynyl methyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, 2-propynyl 2-(methanesulfonyloxy)propionate, di(2-propynyl)oxalate, 2-butyne-1,4-diyl dimethanesulfonate, and 2-butyne-1,4-diyl diformate.

[0168] In particular, 2-propynyl methyl carbonate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, di(2-propynyl)oxalate, and 2-butyne-1,4-diyl dimethanesulfonate are preferred, and 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, di(2-propynyl)oxalate, and 2-butyne-1,4-diyl dimethanesulfonate are more preferred.

[0169] [1-4-13.Phosphazene compounds] The phosphazene compound, which is one aspect of the auxiliary in this embodiment, is not particularly limited as long as it is a compound having an "N=PN group" in the molecule. Examples of the phosphazene compound include cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

[0170] In particular, cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and phenoxypentafluorocyclotriphosphazene are preferred, with methoxypentafluorocyclotriphosphazene and ethoxypentafluorocyclotriphosphazene being more preferred.

[0171] [Mass ratio of main salt to auxiliary] When the non-aqueous electrolyte according to the present embodiment contains an auxiliary other than a specific carbonate compound as an auxiliary, the mass ratio of the content of the auxiliary to the content of the main salt contained in the electrolyte in the non-aqueous electrolyte, that is, the mass ratio represented by auxiliary [g] / main salt [g], is usually 0.00005 to 0.5, preferably 0.0001 to 0.5, more preferably 0.001 to 0.45, more preferably 0.01 to 0.4, even more preferably 0.02 to 0.4, and particularly preferably 0.025 to 0.35. Here, the mass ratio is usually 0.00005 or more, preferably 0.0001 or more, more preferably 0.001 or more, even more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.025 or more, and usually 0.5 or less, preferably 0.45 or less, more preferably 0.4 or less, and even more preferably 0.35 or less. In addition, the content of the main salt and auxiliary agent means the total content of the main salt and auxiliary agent when two or more main salts and auxiliary agents are contained. Depending on the content of the specific anion-containing compound, the content of the specific anion-containing compound is also included in the main salt or auxiliary agent. When the mass ratio is within the above range, the battery characteristics, particularly the rate of increase in internal resistance, can be suppressed. Although the reason for this is unclear, it is believed that by containing the auxiliary and main salt within the above mass ratio range, a coating is formed on the electrode, minimizing side reactions of the electrolyte in the battery system.

[0172] <2.Nonaqueous electrolyte battery> The nonaqueous electrolyte battery according to the present embodiment is a nonaqueous electrolyte battery including a positive electrode and a negative electrode capable of absorbing and releasing metal ions, and a nonaqueous electrolyte solution, the nonaqueous electrolyte solution being the nonaqueous electrolyte solution described in <1. Nonaqueous electrolyte solution>. The nonaqueous electrolyte battery is preferably a nonaqueous electrolyte secondary battery. Among the components of the nonaqueous electrolyte secondary battery, those other than the nonaqueous electrolyte will be described below using a lithium ion secondary battery as an example.

[0173] [2-1. Positive electrode] The positive electrode has a positive electrode active material capable of absorbing and releasing lithium ions on at least a portion of the surface of a current collector.

[0174] [2-1-1. Positive electrode active material] The positive electrode active material used in the positive electrode is not particularly limited as long as it is capable of electrochemically absorbing and releasing metal ions, and examples thereof include lithium transition metal compounds. The positive electrode active material (lithium transition metal compound) used in the positive electrode will be described below.

[0175] [2-1-1-1. Lithium transition metal compounds] The lithium transition metal compound is a compound having a structure capable of desorbing and inserting lithium ions, and examples thereof include sulfides, phosphate compounds, silicate compounds, borate compounds, lithium transition metal composite oxides, etc. Among these, phosphate compounds and lithium transition metal composite oxides are preferred, and lithium transition metal composite oxides are more preferred.

[0176] Examples of the lithium transition metal composite oxide include those having a spinel structure or olivine structure that enable three-dimensional diffusion of lithium ions, and those having a layered structure that enables two-dimensional diffusion of lithium ions. Among these, lithium transition metal composite oxides having a layered structure are preferred from the viewpoint of improving the battery capacity.

[0177] A lithium transition metal composite oxide having a spinel structure is generally represented by the following composition formula (1). Li x’ M' y’ O4···(1) (In formula (1), 0.8≦x'≦1.5, 1.9≦y'≦2.1, and M' contains at least one transition metal element.)

[0178] Lithium transition metal composite oxides with spinel structure include LiMn2O4, LiCoMnO4, and LiNi 0.5 Mn 1.5 O4, LiCoVO4, etc.

[0179] A lithium transition metal composite oxide having an olivine structure is generally represented by the following composition formula (2). Li x” M” y” PO4···(2) (In formula (2), 0.8≦x″≦1.5, 0.9≦y″≦1.1, and M″ contains at least one transition metal element.)

[0180] Examples of M″ include Fe, Ni, Co, and Mn. As a lithium transition metal composite oxide having an olivine structure, specifically, LiFePO 4、 etc.

[0181] A lithium transition metal composite oxide having a layered structure is generally represented by the following composition formula (3). Li 1+x M y O2···(3) (In formula (3), -0.2≦x≦0.5, 0.5≦y≦1.1, and M contains at least one transition metal element.)

[0182] Examples of lithium transition metal composite oxides having a layered structure include LiCoO2, LiNiO2, and LiNi 0.90 Co 0.05 Mn 0.05 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2, Li 1.05 Ni 0.33 Co 0.33 Mn 0.33 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, Li [Li 1 / 3 Mn 2 / 3 ]O2, and solid solutions thereof.

[0183] Among the lithium transition metal composite oxides having a layered structure, from the viewpoint of increasing capacity, a lithium transition metal composite oxide represented by the following composition formula (4) is preferred. Li 1+y M 1 O2(4) (In formula (4), -0.2≦y≦0.5, and M 1 indicates a plurality of elements including at least Ni element, and M 1 The molar ratio of the Ni content to the total content of elements in (Ni / M 1 ) is 0.30 to 1.0.

[0184] In the above composition formula (4), the molar ratio (Ni / M 1 ) is 0.30 or more, preferably 0.40 or more, more preferably 0.50 or more, and is preferably 1.0 or less, more preferably 0.90 or less. 1 ) is 0.30 or more and 1.0 or less, preferably 0.40 or more and 0.90 or less, and more preferably 0.50 or more and 0.90 or less. Molar ratio (Ni / M 1 ) in this range, the compound represented by general formula (I) can easily form a coating on the positive electrode, and a side reaction between the positive electrode and the nonaqueous electrolyte can be suppressed, thereby suppressing the rate of increase in internal resistance of the nonaqueous electrolyte battery after high-temperature storage.

[0185] Specific examples of lithium transition metal oxides having a layered structure represented by the composition formula (4) include LiNiO2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.3 Co0.3 Mn 0.3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.91 Co 0.06 Mn 0.03 O2, LiNi 0.91 Co 0.06 Al 0.03 O2, LiNi 0.90 Co 0.03 Al 0.07 O2, Li 1.00 Ni 0.61 Co 0.20 Mn 0.19 O2, etc.

[0186] Among the lithium transition metal compounds, from the viewpoint of improving battery capacity, lithium transition metal composite oxides having a layered structure are preferred, and lithium transition metal composite oxides represented by the following composition formula (5) are more preferred. Li a1 Ni b1 M 2 c1 O2(5) (In formula (5), M 2 represents at least one element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti, and Er, and is 50.80≦a1≦1.10, 0.30≦b1≦0.98, 0.00≦c1≦0.70, and 0.90≦b1+c1≦1.10.

[0187] In the composition formula (5), b1 is preferably 0.40 or more and 0.98 or less, more preferably 0.45 or more and 0.98 or less, and even more preferably 0.50 or more and 0.98 or less. Here, b1 is 0.30 or more, preferably 0.40 or more, more preferably 0.45 or more, even more preferably 0.50 or more, and 0.98 or less.

[0188] Specific examples of lithium transition metal oxides having a layered structure represented by the composition formula (5) include LiNi 0.90 Co 0.05 Mn 0.05 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.3 Co 0.3 Mn 0.3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.91 Co 0.06 Mn 0.03 O2, LiNi 0.91 Co 0.06 Al 0.03 O2, LiNi 0.90 Co 0.03 Al 0.07 O2, Li 1.00 Ni 0.61 Co 0.20 Mn 0.19 O2, etc.

[0189] In particular, from the viewpoint of the structural stability of the lithium transition metal composite oxide, a lithium transition metal composite oxide represented by the following composition formula (6) is preferable. Li a2 Ni b2 Co c2 M 3 d2 O2(6) (In formula (6), M 3represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti, and Er, and satisfies 0.80≦a2≦1.10, 0.30≦b2≦0.98, 0.01≦c2≦0.70, and 0.01≦d2≦0.60, and satisfies 0.90≦b2+c2+d2≦1.10.

[0190] In the above composition formula (6), b2 is 0.30 or more and 0.98 or less, preferably 0.40 or more and 0.98 or less, more preferably 0.45 or more and 0.98 or less, and even more preferably 0.50 or more and 0.98 or less. Here, b2 is preferably 0.40 or more, more preferably 0.45 or more, and even more preferably 0.50 or more. In the composition formula (6), d2 is preferably 0.01 or more and 0.60 or less, and more preferably 0.10 or more and 0.60 or less. Here, d2 is preferably 0.01 or more, more preferably 0.10 or more, and is preferably 0.60 or less.

[0191] A suitable example of the lithium transition metal composite oxide represented by the above composition formula (6) is LiNi 0.90 Co 0.05 Mn 0.05 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.3 Co 0.3 Mn 0.3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, Li 1.05 Ni 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.91 Co 0.06 Mn 0.03 O2, LiNi 0.91 Co 0.06 Al 0.03O2, LiNi 0.90 Co 0.03 Al 0.07 O2, LiNi 0.61 Co 0.20 Mn 0.19 O2, etc.

[0192] In the above composition formula (4) or (5), in order to enhance the structural stability of the lithium transition metal oxide and suppress structural deterioration during repeated charging and discharging, M 1 Or M 2 It is preferable that the alloy contains Mn or Al, and more preferable that the alloy contains Mn. In the above composition formula (6), in order to enhance the structural stability of the lithium transition metal composite oxide and suppress structural deterioration during repeated charging and discharging, M 3 It is preferable that the alloy contains Mn or Al, and more preferable that the alloy contains Mn. The positive electrode active material is identified and its content is measured by wet decomposition of the sample and then ICP emission spectroscopy.

[0193] [2-1-1-2. Introduction of different elements] The lithium transition metal oxide may further contain an element (foreign element) other than the elements contained in any of the above composition formulas (1) to (5).

[0194] [2-1-1-3. Surface coating] The positive electrode may be one in which a substance (surface-attaching substance) having a different composition from the positive electrode active material is attached to the surface of the positive electrode active material. Examples of the surface-attaching substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, carbonates such as lithium carbonate, etc. These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, dissolving or suspending them in a solvent, adding them to the positive electrode active material by impregnation, and drying them.

[0195] The amount of the surface-attached substance is preferably 1 μmol / g to 1 mmol / g, more preferably 10 μmol / g to 1 mmol / g, relative to the positive electrode active material. Here, the amount of the surface-attached substance is preferably 1 μmol / g or more, more preferably 10 μmol / g or more, and usually 1 mmol / g or less. In this specification, a positive electrode active material having the above-mentioned surface-adhering substance attached to the surface thereof is also referred to as a "positive electrode active material".

[0196] [2-1-1-4. Blend] The positive electrode active material may be used alone or in combination of two or more kinds in any ratio.

[0197] [2-1-2. Positive electrode composition and manufacturing method] The positive electrode having the positive electrode active material can be manufactured by a conventional method. That is, the positive electrode active material and the binder, and if necessary, the conductive material and the thickener, etc. are mixed in a dry state to form a sheet, which is then pressed onto the positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium such as an aqueous solvent or an organic solvent to form a slurry, which is then applied to the positive electrode current collector and dried to form a positive electrode active material layer on the current collector, thereby obtaining a positive electrode. In addition, for example, the positive electrode active material may be roll-formed into a sheet electrode, or may be compression-formed into a pellet electrode. Hereinafter, a case where the slurry is successively applied to the positive electrode current collector and then dried will be described.

[0198] [2-1-2-1. Content of positive electrode active material] The positive electrode is composed of a current collector and a positive electrode active material layer formed on the current collector and containing a positive electrode active material. The content of the positive electrode active material in the positive electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[0199] [2-1-2-2. Electrode density] The positive electrode active material layer obtained by applying and drying the positive electrode active material together with a binder, a conductive material, etc. is preferably compressed by a hand press, a roller press, etc. to increase the packing density of the positive electrode active material. The electrode structure when the positive electrode active material is made into an electrode is not particularly limited, but the density of the positive electrode active material layer present on the current collector is usually 1.5 g / cm 3 More than 4.5g / cm 3 The following is the result.

[0200] [2-1-2-3. Binder] When the positive electrode active material layer is formed by a coating method, the type of binder is not particularly limited as long as it is a material that can be dissolved or dispersed in the liquid medium for the slurry. As the binder, for example, in view of weather resistance, chemical resistance, heat resistance, flame retardancy, etc., fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, etc.; CN group-containing polymers such as polyacrylonitrile, polyvinylidene cyanide, etc. are preferable. In addition, mixtures, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, etc. of the above polymers can also be used. The binder can be used alone or in combination of two or more kinds in any ratio.

[0201] When a resin is used as a binder, the weight-average molecular weight of the resin is arbitrary as long as it does not impair the effects of the present invention, and is usually from 10,000 to 3,000,000. When the molecular weight is in this range, the strength of the electrode is improved, and the electrode can be preferably formed.

[0202] The content of the binder in the positive electrode active material layer is usually from 0.1% by mass to 20% by mass.

[0203] [2-1-2-4.Conductive materials] As the conductive material, any known conductive material can be used. Specific examples thereof include metal materials such as copper and nickel, graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and carbon-based materials such as amorphous carbon such as needle coke. The conductive material may be used alone or in combination of two or more kinds in any ratio.

[0204] The conductive material is usually contained in the positive electrode active material layer in an amount of 0.01% by mass to 20% by mass.

[0205] [2-1-2-5. Current collector] The material of the current collector that holds the positive electrode active material is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and aluminum is preferred.

[0206] The shape of the current collector may be metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, foamed metal, etc. Among these, metal foil or metal thin film is preferable. The metal thin film may be appropriately formed into a mesh shape.

[0207] When the positive electrode current collector has a plate or film shape, the current collector may have any thickness, but it is usually from 1 μm to 1 mm.

[0208] [2-1-2-6. Thickness of positive electrode plate] The thickness of the positive electrode (positive electrode plate) is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the positive electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the positive electrode plate is usually 10 μm or more and 500 μm or less on one side of the current collector. The positive electrode active material layer may be formed on one surface or both surfaces of the current collector.

[0209] [2-1-2-7. Surface coating of positive electrode plate] The positive electrode plate may have a substance having a different composition from the positive electrode active material attached to its surface, and the substance used may be the same as the surface-attached substance that may be attached to the surface of the positive electrode active material.

[0210] [2-2. Negative electrode] The negative electrode has a negative electrode active material capable of absorbing and releasing lithium ions on at least a portion of the surface of a current collector.

[0211] [2-2-1. Negative electrode active material] There are no particular limitations on the negative electrode active material used in the negative electrode, so long as it is capable of electrochemically absorbing and releasing metal ions.

[0212] Specific examples include (i) carbon-based materials, (ii) materials containing metal elements and / or metalloid elements that can be alloyed with Li, (iii) lithium-containing metal composite oxide materials, and (iv) mixtures of the above (i) to (iii). Among these, (i) carbon-based materials, (ii) materials containing metal elements and / or metalloid elements capable of forming an alloy with Li, and (iv) mixtures of the above (i) to (iii) are preferred, in that they have good cycle characteristics and safety as well as excellent continuous charging characteristics, and as (iv), a mixture of a material containing metal elements and / or metalloid elements capable of forming an alloy with Li and graphite is more preferred. These can be used alone or in combination of two or more in any ratio.

[0213] [2-2-1-1. Carbon-based materials] (i) Examples of carbon-based materials include natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite. Of these, natural graphite is preferred. The carbon-based materials can be used alone or in combination of two or more in any ratio.

[0214] Examples of natural graphite include scaly graphite, scaly graphite, and / or graphite particles obtained by subjecting such graphite to treatment such as spheroidization or densification. Among these, from the viewpoint of particle packing ability or charge / discharge rate characteristics, spherical or ellipsoidal graphite particles that have been subjected to spheroidization treatment are preferred. The average particle size (d50) of the graphite particles is usually 1 μm or more and 100 μm or less. Here, the average particle size (d50) is the volume-based average particle size (median size) determined by a laser diffraction / scattering method.

[0215] [2-2-1-2. Properties of carbon-based materials] The carbonaceous material as the negative electrode active material preferably satisfies at least one of the characteristics such as the physical properties and shape shown in the following (1) to (4), and more preferably satisfies a plurality of items at the same time. (1) X-ray diffraction parameters The d value (interlayer distance) of the lattice plane (002 plane) of carbon-based materials determined by X-ray diffraction using the Gakushin method is usually 0.335 nm to 0.360 nm. Also, the crystallite size (Lc) of carbon-based materials determined by X-ray diffraction using the Gakushin method is 1.0 nm or more. (2) Volume-based average particle size The volume-based average particle size of a carbon-based material is the volume-based average particle size (median diameter) determined by a laser diffraction / scattering method, and is usually 1 μm or more and 100 μm or less. (3) Raman R value, Raman half-width The Raman R value of a carbon-based material is a value measured using an argon ion laser Raman spectroscopy method, and is usually 0.01 or more and 1.5 or less. In addition, the 1580 cm -1 The Raman half-width in the vicinity is not particularly limited, but is usually 10 cm -1 More than 100cm -1 The following is the result. (4) BET specific surface area The BET specific surface area of ​​a carbon-based material is the value of the specific surface area measured using the BET method, and is usually 0.1 m 2 ·g -1 More than 100m 2 ·g -1 The following is the result.

[0216] The negative electrode active material may contain two or more carbonaceous materials with different properties, where the properties refer to one or more characteristics selected from the group consisting of X-ray diffraction parameters, volume-based average particle size, Raman R value, Raman half-width, and BET specific surface area, as shown in (1) to (4) above.

[0217] Examples of the carbon-based material containing two or more different types of materials with different properties include a material in which the volume-based particle size distribution is not symmetrical about the median diameter, a material in which two or more carbon-based materials have different Raman R values, and a material in which X-ray diffraction parameters are different.

[0218] [2-2-1-3. Materials containing metallic elements and / or semi-metallic elements that can be alloyed with Li] (ii) As the material containing a metallic element and / or a semi-metallic element capable of being alloyed with Li, any conventionally known material can be used. From the viewpoint of capacity and cycle life, it is preferable that the material is, for example, a metal or semimetal selected from the group consisting of Sb, Si, Sn, Al, As, and Zn. In addition, when the material containing a metal element and / or a semimetal element capable of being alloyed with Li contains two or more kinds of metals, the material may be an alloy material consisting of an alloy of these metals.

[0219] In addition, examples of materials containing metal elements and / or metalloid elements that can be alloyed with Li include oxides, nitrides, carbides, etc. of metals and / or metalloids. The materials may contain two or more metals that can be alloyed with Li. Among these, materials containing Si element are preferred, and metal Si (hereinafter also referred to as "Si") or Si-containing inorganic compounds are more preferred in terms of increasing capacity. In this specification, Si or Si-containing inorganic compounds are collectively referred to as "Si compounds."

[0220] The content of the material containing a metal element and / or a metalloid element capable of forming an alloy with Li is preferably 0.1 to 25 mass % relative to the total mass of the negative electrode active material. 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 below, and as such a material, a Si compound is preferable in terms of increasing capacity.

[0221] Si compounds are inorganic compounds containing Si, such as SiO x (0≦x≦2), etc. Metal compounds alloyed with Li include Li ySi (0 < y ≤ 4.4), Li 2z SiO 2+z (0 < z ≤ 2), etc. can be mentioned.

[0222] As the Si compound, silicon oxide (SiO x1 , 0 < x1 ≤ 2) is preferable in that it has a larger theoretical capacity compared to graphite. Also, amorphous Si or nano-sized Si crystals are preferable in that alkali ions such as lithium ions can easily enter and exit, and it is possible to obtain a high capacity.

[0223] When the material containing a metal element and / or a metalloid element capable of alloying with Li is in the form of particles, the average particle diameter (d 50 ) is usually 0.01 μm or more and 10 μm or less from the viewpoint of cycle life.

[0224] [2-2-1-4. Lithium-containing metal composite oxide material] (iii) As the lithium-containing metal composite oxide material, there is no particular limitation as long as it can occlude and release lithium ions. Specifically, from the viewpoint of high current density charge and discharge characteristics, a lithium-containing metal composite oxide material containing titanium is preferable, a composite oxide of lithium and titanium (hereinafter also referred to as "lithium titanium composite oxide") is more preferable, and a lithium titanium composite oxide having a spinel structure is even more preferable because it greatly reduces the output resistance.

[0225] Also, lithium and / or titanium of the lithium titanium composite oxide may be substituted with at least one element selected from the group consisting of other metal elements, for example, Al, Ga, Cu, and Zn.

[0226] As the lithium titanium composite oxide, Li 4 / 3 Ti 5 / 3 O4, Li1Ti2O4, and Li 4 / 5 Ti 11 / 5 O4 are preferable. Also, as the lithium titanium composite oxide in which a part of lithium and / or titanium is substituted with other elements, for example, Li 4 / 3 Ti 4 / 3 Al1 / 3 O4 is also preferred.

[0227] [2-2-1-5. Mixture of graphite and material containing metallic and / or semi-metallic elements capable of being alloyed with Li] (iv) is a mixture of the above (i) carbonaceous material, (ii) material containing a metal element and / or a metalloid element capable of forming an alloy with Li, and (iii) lithium-containing metal composite oxide material. Among these, a mixture of a material containing a metal element and / or a metalloid element capable of forming an alloy with Li and graphite is preferred.

[0228] The mixture of graphite and a material containing a metal element and / or a metalloid element capable of being alloyed with Li may be the above (ii) mixture in which the material containing a metal element and / or a metalloid element capable of being alloyed with Li and graphite are mixed in the state of independent particles, or it may be a composite in which the material containing a metal element and / or a metalloid element capable of being alloyed with Li is present on the surface or inside of graphite particles.

[0229] The content ratio of the material containing a metallic element and / or a metallic element capable of being alloyed with Li to the total of the material containing a metallic element and / or a metallic element capable of being alloyed with Li and graphite is typically 1 mass% or more and 99 mass% or less.

[0230] The negative electrode active material is identified and its content is measured by alkali fusion of the sample and then ICP emission spectroscopy.

[0231] [2-2-2. Negative electrode composition and manufacturing method] The negative electrode may be produced by any known method as long as the effect of the present invention is not impaired. For example, the negative electrode active material can be prepared by adding a binder, a liquid medium such as an aqueous solvent or an organic solvent, and, if necessary, a thickener, a conductive material, a filler, and the like to the negative electrode active material to form a slurry, which is then applied to a current collector, dried, and pressed to form a negative electrode active material layer.

[0232] [2-2-2-1. Content of negative electrode active material] The negative electrode is composed of a current collector and a negative electrode active material layer containing a negative electrode active material formed on the current collector. The content of the negative electrode active material in the negative electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[0233] [2-2-2-2. Electrode density] The negative electrode active material layer obtained by applying the negative electrode active material together with a binder, a thickener, etc., and drying it is preferably compressed by a hand press, a roller press, etc., in order to increase the packing density of the negative electrode active material. The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material layer present on the current collector is usually 1 g / cm 3 More than 2.2g / cm 3 The following is the result.

[0234] [2-2-2-3. Binder] There are no particular limitations on the binder, so long as it is a material that is stable in the non-aqueous electrolyte solution and the liquid medium used in the production of the electrode. Specific examples thereof include rubber-like polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluororubber, acrylonitrile-butadiene rubber (NBR), and ethylene-propylene rubber, and fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and tetrafluoroethylene-ethylene copolymers. These may be used alone or in combination of two or more in any ratio.

[0235] The content of the binder relative to the negative electrode active material is usually 0.1% by mass or more and 20% by mass or less. In particular, when the binder contains a rubber-like polymer such as SBR as a main component, the content of the binder relative to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less. When the binder contains a fluorine-based polymer such as polyvinylidene fluoride as a main component, the content of the binder relative to the negative electrode active material is usually 1% by mass or more and 15% by mass or less.

[0236] [2-2-2-4. Thickener] A thickener is typically used to adjust the viscosity of the slurry. The thickener is not particularly limited, but specific examples include carboxymethylcellulose and its salts, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, etc. These may be used alone or in combination of two or more kinds in any ratio.

[0237] When a thickener is used, the content of the thickener relative to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less.

[0238] [2-2-2-5. Current collector] Any known current collector can be used to hold the negative electrode active material. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel, with copper being particularly preferred in terms of ease of processing and cost.

[0239] The shape of the negative electrode current collector may be metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, foamed metal, etc. Among these, metal foil or metal thin film is preferable. The metal thin film may be appropriately formed into a mesh shape.

[0240] When the negative electrode current collector has a plate or film shape, the current collector may have any thickness, but it is usually from 1 μm to 1 mm.

[0241] [2-2-2-6. Thickness of negative electrode plate] The thickness of the negative electrode (negative electrode plate) is designed to match the positive electrode (positive electrode plate) to be used and is not particularly limited, but the thickness of the negative electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the negative electrode material is usually 15 μm or more and 300 μm or less.

[0242] [2-2-2-7. Surface coating of negative electrode plate] The negative electrode plate may have a surface to which a substance having a different composition from the negative electrode active material (surface-attached substance) is attached. Examples of the surface-attached substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate.

[0243] [2-3. Separator] A separator is usually interposed between the positive electrode and the negative electrode to prevent short circuiting. In this case, the non-aqueous electrolyte is usually impregnated into the separator before use. There are no particular limitations on the material and shape of the separator, and any known material can be used as long as it does not impair the effects of the present invention.

[0244] [2-4.Battery design] [2-4-1. Electrode group] The electrode group may have either a laminated structure in which the positive electrode plate and the negative electrode plate are sandwiched between the separator, or a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator between them. The ratio of the volume of the electrode group to the internal volume of the battery (electrode group occupancy rate) is usually 40% or more and 90% or less.

[0245] [2-4-2. Current collection structure] In the case where the electrode group has the above-mentioned laminated structure, a structure in which the metal core parts of the electrode layers are bundled and welded to a terminal is preferably used. A structure in which multiple terminals are provided in the electrode to reduce resistance is also preferably used. In the case where the electrode group has the above-mentioned wound structure, the internal resistance can be reduced by providing multiple lead structures on each of the positive electrode and the negative electrode and bundling them to a terminal.

[0246] [2-4-3.Protection elements] As protective elements, a PTC (Positive Temperature Coefficient) element whose resistance increases as heat is generated due to excessive current, a temperature fuse, a thermistor, a valve (current cut-off valve) that cuts off the current flowing in the circuit due to a sudden increase in the internal pressure or temperature of the battery during abnormal heat generation, etc. can be used. It is preferable to select the protective element such that it will not operate under normal use at high currents, and it is even more preferable to design the device so that abnormal heat generation or thermal runaway does not occur even without the protective element.

[0247] [2-4-4. Exterior body] A non-aqueous electrolyte battery is usually configured by housing the non-aqueous electrolyte according to the present embodiment, a negative electrode, a positive electrode, a separator, etc., in an exterior body (exterior case). There are no limitations on this exterior body, and any known exterior body can be used as long as it does not impair the effects of the present invention.

[0248] The material of the exterior case is not particularly limited as long as it is a substance stable against the nonaqueous electrolyte used, but from the viewpoints of weight reduction and cost, metals or laminate films of iron, aluminum, and aluminum alloys are preferably used. In particular, iron is preferred from the viewpoint of pressure resistance for operating the current cutoff valve.

[0249] Examples of exterior cases using the above metals include those in which metals are welded to each other by laser welding, resistance welding, or ultrasonic welding to form a sealed, airtight structure, and those in which the above metals are used with a resin gasket interposed between them to form a crimped structure.

[0250] [2-4-5. Shape] The shape of the exterior case of the nonaqueous electrolyte battery is also arbitrary, and may be, for example, cylindrical, rectangular, laminated, coin-shaped, large, or the like. EXAMPLES

[0251] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

[0252] <Compound> The compounds used in the examples and comparative examples are shown below. Compound 1: Trimethylsilylmethyl methanesulfonate [Compound (A1-1)]

[0253] [ka]

[0254] Compound 2: Bis(methylsulfonyloxymethyl)dimethylsilane [Compound (A2-1)]

[0255] [ka]

[0256] Compound 3: Lithium difluorophosphate (a compound containing a specific anion) Compound 4: Lithium fluorosulfonate (a compound containing a specific anion) Compound 5: Lithium bis(fluorosulfonyl)imide (a compound containing a specific anion) Compound 6: Lithium bis(oxalato)borate (a compound containing a specific anion) Compounds 1 and 2 used were those obtained by the following Synthesis Examples 1 and 2, respectively, and commercially available products were used for compounds 3 to 6. Compound 1 corresponds to the compound represented by general formula (I), and compound 2 corresponds to both the compound represented by general formula (I) and the compound represented by general formula (II).

[0257] <Synthesis Example> The various analytical methods for the compounds obtained in the following synthesis examples are as follows.

[0258] [Nuclear magnetic resonance (NMR) analysis] 1 H, 13 C-NMR was measured at 400 and 101 MHz using a Bruker 400 Ultrashield (trade name). The sample was dissolved in deuterated chloroform (CDCl3) and measured.

[0259] [Gas Chromatography (GC) Analysis] 100 μL of the sample was dissolved in 1 mL of diethyl ether, and the resulting solution was analyzed using a GC analyzer (manufactured by Shimadzu Corporation, product name: GC-2010) under the following conditions. Column: DB-1 (length 30 m, inner diameter 0.32 mm, film thickness 0.25 μm, Agilent Technologies) Detector: FID Temperature: 40℃ to 280℃, increased at 10℃ / min. Purity was calculated from the peak area %.

[0260] [Synthesis Example 1 [Synthesis of Compound 1: Trimethylsilylmethyl methanesulfonate]] Under a nitrogen atmosphere, trimethylsilylmethanol (2.00 g, 19.2 mmol), diethyl ether (10 mL), and triethylamine (2.94 mL, 21.1 mmol) were charged into a reactor, and methanesulfonyl chloride (2.20 g, 19.2 mmol) was added dropwise under ice cooling, and the mixture was stirred at room temperature for 1 hour. Under ice cooling, 1 mol / L hydrochloric acid solution was added to quench the mixture, and the organic layer was washed with a saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, and then dried over anhydrous sodium sulfate. After filtering off the sodium sulfate, the filtrate was concentrated to obtain trimethylsilylmethyl methanesulfonate (2.75 g, 15.1 mmol). The purity was estimated to be >99% by GC analysis. 1 H-NMR, 13 The results of C-NMR analysis were as follows: 1 H-NMR (400MHz, CDCl3): δ=3.87(s,2H),2.98(s,3H),0.14(s,9H) 13 C-NMR(101MHz,CDCl3):δ=62.9,36.0,-3.5

[0261] [Synthesis Example 2 [Synthesis of Compound 2: bis(methylsulfonyloxymethyl)dimethylsilane]] Bis(chloromethyl)dimethylsilane (5.00 g, 31.8 mmol) was dissolved in acetone (50 mL), sodium iodide (14.3 g, 95.5 mmol) was added, and the mixture was heated under reflux for 2.5 hours. After concentrating the solvent, dichloromethane was added and the precipitated inorganic salt was filtered off. The filtrate was concentrated to obtain bis(iodomethyl)dimethylsilane (10.6 g, 31.1 mmol). 1 The H-NMR analysis results were as follows: 1 H-NMR (400MHz, CDCl3): δ=2.13(s,4H),0.31(s,6H)

[0262] Next, silver methanesulfonate (3.94 g, 19.4 mmol) was dissolved in acetonitrile (50 mL), and bis(iodomethyl)dimethylsilane (3.00 g, 8.82 mmol) was added. After heating under reflux for 2.5 hours, the precipitated solid was filtered off, and the filtrate was concentrated. The mixture was purified by silica gel column chromatography to obtain bis(methylsulfonyloxymethyl)dimethylsilane (1.86 g, 6.73 mmol). The purity was estimated to be >99% by GC analysis. 1 H-NMR, 13 The results of C-NMR analysis were as follows: 1 H-NMR (400MHz, CDCl3): δ=4.02(s,4H),3.01(s,6H),0.29(s,6H) 13 C-NMR(101MHz,CDCl3):δ=59.4,36.2,-6.7

[0263] <Examples 1 to 8 and Comparative Examples 1 to 7> [Preparation of positive electrode] The positive electrode active material was lithium nickel cobalt manganese composite oxide (Li 1.0 Ni 0.6 Co 0.2 Mn 0.290 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 with a disperser to form a slurry. This was evenly applied to both sides of a 15 μm thick aluminum foil current collector, dried, and pressed to form a positive electrode.

[0264] [Preparation of negative electrode] 49 parts by mass of graphite powder was mixed with 50 parts 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) as a thickener and binder, and mixed in a disperser to form a slurry. The obtained slurry was applied to one side of a 10 μm-thick copper foil as a current collector, dried, and pressed to form a negative electrode.

[0265] [Preparation of non-aqueous electrolyte] In a dry argon atmosphere, thoroughly dried LiPF6 was dissolved as an electrolyte at 1.2 mol / L (14.5%, as the concentration in the non-aqueous electrolyte) in a mixture of ethylene carbonate (EC), dimethyl carbonate (EMC), and ethyl methyl carbonate (DMC) (volume ratio of EC:EMC:DMC=3:4:3), and 1 mass % of vinylene carbonate was dissolved therein to prepare reference electrolyte 1. Non-aqueous electrolyte solutions were prepared by adding compounds 1 to 6 to the reference electrolyte solution 1 in the amounts shown in Table 1 below. However, Comparative Example 1 is the reference electrolyte solution 1 itself to which no other compounds are added, and is a non-aqueous electrolyte solution that serves as a reference for evaluation. The contents of compounds 1 to 6 are the contents (parts by mass) when the reference electrolyte solution 1 is taken as 100 parts by mass. In Table 1, "-" means that no compound is added.

[0266] [Manufacturing non-aqueous electrolyte batteries] The above positive electrode, negative electrode, and polyolefin separator were laminated in the order of negative electrode, separator, and positive electrode to prepare a battery element. This battery element was inserted into a bag made of a laminate film in which both sides of aluminum (40 μm thick) were coated with a resin layer so that the positive and negative terminals were protruding, and then each of the nonaqueous electrolyte solutions prepared as above was injected into the bag and vacuum sealed to prepare a laminate type nonaqueous electrolyte battery. The nonaqueous electrolyte battery was immersed in a water bath to measure the volume. This nonaqueous electrolyte battery is a secondary battery.

[0267] <Evaluation of non-aqueous electrolyte batteries> [Initial conditioning] In a thermostatic bath at 25°C, the nonaqueous electrolyte battery prepared by the above method was charged at a constant current of 0.05C (the current value at which the rated capacity based on the discharge capacity at a 1-hour rate is discharged in 1 hour is defined as 1C; the same applies below) to 3.7V, then charged at a constant current / constant voltage of 0.2C to a voltage of 4.25V, and then discharged at a constant current of 0.2C to 2.8V. Furthermore, the non-aqueous electrolyte secondary battery was stabilized by constant current-constant voltage charging at 0.2C to 4.1V, and then storing at high temperature at 60°C for 24 hours. Thereafter, the battery was discharged at a constant current to 2.8V at 25°C, and then charged at a constant current-constant voltage at 0.2C to a voltage of 4.25V. Thereafter, the battery was discharged at a constant current of 0.2C to 2.8V. Thereafter, constant current-constant voltage charging was performed at 0.2 C at 25° C. up to a voltage of 3.72 V. These were then discharged at 0.05 C, 0.1 C, 0.15 C, and 0.2 C at 25° C., and the voltage was measured after 10 seconds. The internal resistance was calculated from this current-voltage line and used as the "initial discharge internal resistance."

[0268] [Charged storage test] The non-aqueous electrolyte battery after the initial conditioning was charged at a constant current and constant voltage at 0.2C to 4.25V, and then stored at high temperature at 60°C for 2 weeks. The non-aqueous electrolyte battery was then cooled to 25°C, discharged at a constant current of 0.2C to 2.8V, and charged at a constant current and constant voltage of 0.2C to 4.25V. The battery was further discharged at a constant current of 0.2C to 2.8V, and then charged at a constant current and constant voltage of 0.2C to a voltage of 3.72V. The battery was discharged at a constant current of 0.05C, 0.1C, 0.15C, and 0.2C for 10 seconds in a thermostatic chamber at 25°C, and the voltage after discharge was measured. The internal resistance was calculated from this current-voltage line and was taken as the "discharge internal resistance after storage".

[0269] Using the value of "initial discharge internal resistance" obtained by the above [initial conditioning] and the value of "post-storage discharge internal resistance" obtained by the above [charged storage test], the "internal resistance increase rate" was calculated according to the following formula. "Internal resistance increase rate" = "internal resistance after discharge after storage" ÷ "initial discharge internal resistance"

[0270] The "internal resistance increase rate" of each example is shown in Table 1 below, and these are shown as relative values ​​when the "internal resistance increase rate" of Comparative Example 1 is set to 100.0. Moreover, the "ratio" shown in Table 1 indicates the ratio of the content of the compound represented by general formula (I) to the content of the specific anion-containing compound in the nonaqueous electrolyte solution.

[0271] [Table 1]

[0272] From Table 1, it can be seen that the nonaqueous electrolyte batteries with nonaqueous electrolyte solutions (Examples 1 to 8) containing a compound represented by general formula (I) and at least one specific anion-containing compound selected from an anion-containing compound having a P=O bond and a PF bond, an anion-containing compound having an S=O bond and an SX bond, and an oxalate anion-containing compound can suppress the internal resistance increase rate after high-temperature storage. This can be confirmed by comparison with nonaqueous electrolyte batteries with nonaqueous electrolyte solutions not containing any of the above compounds (Comparative Example 1) and nonaqueous electrolyte solutions containing only one of the above compounds (Comparative Examples 2 to 7).

[0273] It is believed that the above results are due to the effect of the present invention being achieved by the compound represented by general formula (I) reacting favorably with the specific anion-containing compound to form a favorable composite coating on the surface of the electrode active material. [Industrial Applicability]

[0274] The nonaqueous electrolyte according to the present embodiment can be used in a nonaqueous electrolyte battery to suppress the internal resistance increase rate during high-temperature storage in a charged state. Therefore, the nonaqueous electrolyte battery of the present invention can be suitably used in all fields, such as electronic devices, in which nonaqueous electrolyte batteries have been used in the past. In addition, the nonaqueous electrolyte battery according to the present embodiment can be used in various known applications. Specific examples of applications include notebook computers, pen-input personal computers, mobile personal computers, electronic book players, mobile phones, mobile fax machines, mobile copiers, mobile printers, mobile audio players, small video cameras, headphone stereos, video movie machines, liquid crystal televisions, handheld cleaners, portable CDs, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power sources, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting equipment, toys, game equipment, watches, power tools, strobes, cameras, home backup power sources, business backup power sources, load leveling power sources, and natural energy storage power sources. The compound according to the present embodiment can be used as an electrolyte for a non-aqueous electrolyte in the battery field, more specifically, as an additive contained in the electrolyte, thereby suppressing the internal resistance increase rate of a non-aqueous electrolyte battery. In addition, the compound can be used for various known applications in the fields of electronic materials, biocompatible materials, functional materials, and organic synthetic chemistry. Specific examples of applications include coating agents, surface modifiers, and raw materials and intermediates for pharmaceuticals, pesticides, dyes, and surfactants.

Claims

1. The electrolyte comprises an electrolyte, a non-aqueous solvent, and a compound represented by general formula (I), The electrolyte is a non-aqueous electrolyte solution containing at least one specific anion-containing compound selected from the group consisting of an anion-containing compound having a P═O bond and a P-F bond, an anion-containing compound having an S═O bond and an S-X bond (X: heteroatom), and an oxalate anion-containing compound. 【Chemistry 1】 (In general formula (I), R １ represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R ２ and R ３ each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R ４ represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, and n represents an integer of 1 to 4.

2. In the general formula (I), R ２ and R ３ The nonaqueous electrolyte solution according to claim 1 , wherein both are hydrogen atoms.

3. The nonaqueous electrolyte solution according to claim 1 , wherein in the general formula (I), n is 1 or 2.

4. In the general formula (I), R ４ The nonaqueous electrolyte solution according to claim 1 , wherein is a methyl group.

5. 2. The nonaqueous electrolyte solution according to claim 1, wherein the specific anion-containing compound is an anion-containing compound having the P═O bond and the P—F bond.

6. The non-aqueous electrolyte according to claim 1, wherein the content of the compound represented by the general formula (I) in the non-aqueous electrolyte is 0.001 to 10 mass %.

7. The nonaqueous electrolyte solution according to claim 1 , wherein a mass ratio of the content of the compound represented by the general formula (I) to the content of the specific anion-containing compound is 0.01 or more and 100 or less.

8. The non-aqueous electrolyte according to claim 1, wherein the content of the specific anion-containing compound in the non-aqueous electrolyte is 0.001 to 5 mass %.

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

10. 10. The nonaqueous electrolyte secondary battery according to claim 9, wherein the positive electrode comprises a positive electrode active material, the positive electrode active material being a lithium transition metal compound.

11. A compound represented by the following general formula (II): 【Chemistry 2】 (In general formula (II), R ２１ represents a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R ２２ and R ２３ each independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms which may be substituted with a halogen atom; R ２４ represents an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom; ２ represents an integer from 2 to 4.)

12. A compound represented by the following formula (A2-1): 【Chemistry 3】

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