Non-aqueous electrolyte and non-aqueous electrolyte battery

Abstract

The present disclosure provides a non-aqueous electrolyte comprising: (I) a solute; (II) a non-aqueous organic solvent; (III) a compound represented by general formula (1) disclosed in the specification; (IV) a compound represented by general formula (4) disclosed in the specification; and (V) at least one compound selected from the group consisting of nitrates, compounds represented by general formula (2) disclosed in the specification, and compounds represented by general formula (3) disclosed in the specification, wherein the mass ratio (V) / {(III)+(IV)} of the amount of (V) to the total amount of (III) and (IV) is at least 0.0040.

Description

Non-aqueous electrolyte and non-aqueous electrolyte battery

[0001] The present disclosure relates to a non-aqueous electrolyte and a non-aqueous electrolyte battery.

[0002] In recent years, there has been a rapid increase in demand for high-capacity, high-output, and high-energy-density batteries that can be installed as auxiliary power sources in electric vehicles, hybrid vehicles, and fuel cell vehicles, as well as in small-sized, high-energy-density energy storage systems for information-related devices and communication devices, such as personal computers, video cameras, digital cameras, mobile phones, and smartphones. There is also a growing demand for batteries that can be used for long periods of time in large-scale energy storage systems for power applications, such as power storage. Non-aqueous electrolyte batteries, such as lithium-ion batteries, lithium batteries, and lithium-ion capacitors, are being actively developed as candidates for these various energy storage systems.

[0003] Lithium secondary batteries are primarily composed of a positive electrode, a non-aqueous electrolyte, and a negative electrode. Known negative electrodes for lithium secondary batteries include metallic lithium, metal compounds capable of absorbing and releasing lithium (e.g., elemental metals, oxides, and lithium alloys), and carbon materials. In particular, lithium secondary batteries using carbon materials such as coke, artificial graphite, and natural graphite have been widely used. For example, it has been reported that lithium secondary batteries using highly crystalline carbon materials such as natural graphite and artificial graphite as negative electrode materials undergo reductive decomposition of the non-aqueous organic solvent in the non-aqueous electrolyte on the negative electrode surface during charging, resulting in decomposition products and gases that inhibit the inherent electrochemical reactions of the battery, resulting in reduced cycle performance.

[0004] Furthermore, lithium secondary batteries using metals or oxides such as lithium metal, its alloys, silicon, and tin as negative electrode materials have high initial capacities, but the negative electrode material becomes increasingly pulverized during cycling, making the nonaqueous organic solvent more susceptible to reductive decomposition than carbon-based negative electrodes. This results in a decrease in the first-cycle charge / discharge efficiency due to an increase in the initial irreversible capacity of the battery, and a significant decrease in battery performance, such as battery capacity and cycle characteristics. When lithium cations are inserted into the negative electrode during first-cycle charging, the negative electrode reacts with the lithium cations or the negative electrode with the electrolyte solvent, forming a coating on the negative electrode surface primarily composed of lithium oxide, lithium carbonate, or lithium alkyl carbonate. This coating on the electrode surface is called the solid electrolyte interface (SEI), and its properties have a significant impact on battery performance, such as suppressing reductive decomposition of the solvent and reducing battery performance degradation. As described above, due to the accumulation of decomposition products of the nonaqueous organic solvent, the generation of gas, the adverse effects of pulverization of the negative electrode material, and the like, it becomes difficult to smoothly store and release lithium into and from the negative electrode, resulting in a problem of significant deterioration in battery characteristics such as cycle characteristics.

[0005] The positive electrode may be, for example, LiCoO ２ , LiMn ２ O ４ , LiNiO ２ , LiFePO ４ It is known that lithium secondary batteries using these materials experience localized oxidative decomposition of the nonaqueous organic solvent in the nonaqueous electrolyte at the interface between the positive electrode material and the nonaqueous electrolyte when heated to high temperatures in a charged state, and the resulting decomposition products and gases have been reported to inhibit the inherent electrochemical reactions of the battery, resulting in a decrease in battery performance such as cycle characteristics. As with the negative electrode, a coating of oxidative decomposition products is formed on the surface of the positive electrode, and this is known to play an important role in suppressing the oxidative decomposition of the solvent and reducing the amount of gas generated.

[0006] As described above, in conventional lithium secondary batteries, decomposition products and gases generated when the non-aqueous electrolyte decomposes on the positive electrode and the negative electrode inhibit the movement of lithium ions and cause the battery to swell, thereby causing a decrease in battery performance. In order to overcome these issues and to improve battery performance, including long-term durability and output characteristics, it is important to form an SEI that has high ionic conductivity and low electronic conductivity and is stable over a long period of time. Widespread attempts have been made to actively form a good SEI by adding a small amount (usually 0.01% by mass or more and 10% by mass or less) of a compound called an additive to the non-aqueous electrolyte.

[0007] For example, Patent Document 1 describes that combining a specific sulfonylimide salt or phosphorylimide salt with an oxalate complex improves high-temperature cycle characteristics and suppresses deterioration of high-temperature storage characteristics. Patent Document 2 describes that adding a specific fluorine-containing imide salt to an electrolyte solution achieves a balanced effect of suppressing an increase in internal resistance at low temperatures and suppressing gas generation at high temperatures. Patent Document 3 describes that combining a fluorine-containing cyclic carbonate with lithium nitrate forms an SEI that is durable for Si-based negative electrodes, improving cycle characteristics. Patent Document 4 discloses that adding a phosphite ester compound to a nonaqueous electrolyte solution at 0.0005 to 2% by weight of the nonaqueous electrolyte solution reduces the HF content in the nonaqueous electrolyte solution and stabilizes the color when stored at 50°C. Patent Document 5 describes that adding a carbodiimide compound to a nonaqueous electrolyte solution traps moisture carried over from the nonaqueous electrolyte solution and battery components, thereby suppressing the generation of hydrogen fluoride, which causes battery degradation.

[0008] Japanese Patent Publication No. 2013-051122 Publication International Publication No. 2017 / 111143 Publication Japanese Special Publication No. 2016-523429 Publication China Publication No. 1601799 Publication Japanese Patent Publication No. 10-294129

[0009] However, the inventors' investigations have revealed that, although the use of nonaqueous electrolytes containing phosphoryl imide salts and oxalate complexes as described in Patent Documents 1 and 2 does indeed improve battery performance (suppression of internal resistance increase, high-temperature cycle characteristics, and gas suppression), there may be a problem of coloration of the electrolyte when the nonaqueous electrolyte is stored in a room temperature (25°C) environment. Furthermore, there has been no report on the effect of lithium nitrate described in Patent Document 3 in improving the stability of the electrolyte. Furthermore, it has been found that simply adding the phosphite ester-based compound described in Patent Document 4 in the concentration range described in Patent Document 4 does not solve the above-mentioned coloration problem. Furthermore, while carbodiimide compounds such as those described in Patent Document 5 improve the stability of the electrolyte, there has been no report on their use in combination with nonaqueous electrolytes containing phosphoryl imide salts and oxalate complexes.

[0010] An object of the present invention is to provide a nonaqueous electrolyte that can exhibit excellent battery performance when used in a nonaqueous electrolyte battery and can suppress coloration during long-term storage at room temperature (25°C), and a nonaqueous electrolyte battery using the nonaqueous electrolyte.

[0011] As a result of intensive research into solving these problems, the present inventors have found that the above problems can be solved by blending at least one compound selected from a specific phosphorus-containing compound such as a nitrate salt, a phosphite ester compound, and a carbodiimide compound in a specific ratio in a non-aqueous electrolyte solution containing a solute, a non-aqueous organic solvent, a specific phosphoryl imide salt, and a specific boron-, phosphorus-, or silicon-based complex such as an oxalate complex. Specifically, the above problems can be solved by the following configuration.

[0012] [1] A non-aqueous electrolyte solution comprising: (I) a solute; (II) a non-aqueous organic solvent; (III) a compound represented by the following general formula (1); (IV) a compound represented by the following general formula (4); and (V) at least one compound selected from the group consisting of a nitrate, a compound represented by the following general formula (2), and a compound represented by the following general formula (3), wherein the mass ratio (V) / {(III)+(IV)} of the amount of (V) to the total amount of (III) and (IV) is 0.0040 or more.

[0013]

[0014] [In general formula (1), M ａ１＋ is an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a1 represents an integer equal to the valence of the corresponding cation. a1 to d1 represent integers of 1 to 2, and a1×b1=c1×d1 is satisfied. X is a sulfur atom or a phosphorus atom, and when X is a sulfur atom, m is 2, and R ４ is absent, and when X is a phosphorus atom, m is 1. １ ~R ４ are each independently an organic group selected from a fluorine atom, an oxygen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond.]

[0015]

[0016] In the general formula (4), W represents a boron atom, a phosphorus atom, or a silicon atom, n1 represents 1 or 2, n2 represents 2 or 4, and e represents 0 or 1. When e is 0, R ４１ does not exist, and R ４１ The Y written on both sides of ３ and the carbonyl group are directly bonded. ４１ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a halogenated alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a heteroatom in the structure. When n1 is 2 or more, n1 R ４１ may be bonded to each other), and R ４２represents a halogen atom, Y １ , Y ２ each independently represents an oxygen atom or a sulfur atom; Y ３ represents a carbon atom or a sulfur atom. ３ is 1 when it is a carbon atom, and 1 or 2 when it is a sulfur atom. ａ＋ represents an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a represents the valence of the corresponding cation. a to d are 1 or 2, and a×b=c×d is satisfied.

[0017]

[0018] [In the general formula (2), p, q, and r each independently represent 0 or 1; R ５ ~R ７ are each independently a fluorine atom or a hydrocarbon group having 1 to 20 carbon atoms which may be partially or completely fluorinated, and R ５ and R ６ , R ５ and R ７ , or R ６ and R ７ may be bonded to each other to form a ring structure.

[0019]

[0020] [In general formula (3), R ８ , and R ９ are each independently a hydrocarbon group having 1 to 20 carbon atoms.] [2] The nonaqueous electrolyte solution according to [1], wherein the (V) / {(III)+(IV)} is 0.0100 to 1.5000. [3] The R in the general formula (1) １ ~R ４[4] The nonaqueous electrolyte according to any one of [1] to [3], wherein the compound represented by the general formula (1) is a bis(difluorophosphoryl)imide salt or a (fluorosulfonyl)(difluorophosphoryl)imide salt. [5] The nonaqueous electrolyte according to any one of [1] to [4], wherein the compound represented by the general formula (4) is an oxalate salt compound. [6] The nonaqueous electrolyte according to any one of [1] to [4], wherein q, r, and s in the general formula (2) are all 1, and R ５ ~R ７ [7] The nonaqueous electrolyte solution according to any one of [1] to [5], wherein R in the general formula (3) is the same as or represents a hydrocarbon group having 1 to 20 carbon atoms, which may be partially or completely fluorinated. ８ , R ９ The nonaqueous electrolyte according to any one of [1] to [6], wherein the atom bonded to the nitrogen atom as the compound represented by formula (3) is a secondary carbon atom. [8] The nonaqueous electrolyte according to any one of [1] to [7], wherein the compound represented by formula (3) is at least one selected from the group consisting of N,N'-diisopropylcarbodiimide and N,N'-dicyclohexylcarbodiimide. [9] The nonaqueous electrolyte according to any one of [1] to [8], wherein (V) contains a nitrate, and the content of the nitrate relative to the total amount of the nonaqueous electrolyte is 1 mass % or less.

[10] The nonaqueous electrolyte according to any one of [1] to [9], wherein the nonaqueous electrolyte contains fluoroethylene carbonate.

[11] The nonaqueous electrolyte according to any one of [1] to [9], wherein (I) is LiPF ６ , LiBF ４ , LiSbF ６ , LiAsF ６ , LiClO ４ , LiN(FSO ２ ) ２ , LiAlO ２ , LiAlCl ４

[12] The nonaqueous electrolyte solution according to any one of [1] to

[10] , wherein (I) is at least one selected from the group consisting of NaPF 6, LiCl 6, and LiI 6. ６ , NaBF ４ , NaSbF ６ , NaAsF ６ , NaClO４ 、NαN(FSO ２ ) ２ 、NaAlO ２ 、NaAlCl ４The nonaqueous electrolyte solution according to any one of [1] to

[10] , wherein (II) is at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids.

[13] The nonaqueous electrolyte solution according to any one of [1] to

[12] , wherein (II) comprises at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids.

[14] The nonaqueous electrolyte solution according to

[13] , wherein the cyclic ester comprises a cyclic carbonate.

[15] The nonaqueous electrolyte solution according to

[14] , wherein the cyclic carbonate comprises at least one selected from the group consisting of ethylene carbonate and propylene carbonate.

[16] The nonaqueous electrolyte solution according to

[13] , wherein the chain ester comprises a chain carbonate.

[17] The nonaqueous electrolyte solution according to

[16] , wherein the chain carbonate comprises at least one selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, and methyl propyl carbonate.

[18] The nonaqueous electrolyte solution according to

[16] , further comprising vinylene carbonate, difluorophosphate salts, fluorosulfonate salts, 1,3-propene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, ethynylethylene carbonate, trans-difluoroethylene carbonate, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, methylenemethane disulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, triporpigyl phosphate,

[18] The non-aqueous electrolyte solution according to any one of [1] to

[17] , which contains at least one selected from tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(picolinato)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-di(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylsulfamoyl fluoride), tetravinylsilane, trivinylmethylsilane, t-butylbenzene, t-amylbenzene, fluorobenzene, and cyclohexylbenzene.

[19] A nonaqueous electrolyte battery comprising at least a positive electrode, a negative electrode, a separator, and the nonaqueous electrolyte according to any one of [1] to

[18] .

[0021] According to the present disclosure, it is possible to provide a nonaqueous electrolyte that can exhibit excellent battery performance when used in a nonaqueous electrolyte battery and can suppress coloration during long-term storage at room temperature (25°C), and a nonaqueous electrolyte battery using the nonaqueous electrolyte.

[0022] In this specification, the word "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0023] The present disclosure will be described in detail below, but the following description of the constituent elements is an example of an embodiment of the present disclosure, and the present disclosure is not limited to these specific contents.

[0024] 1. Regarding the Non-Aqueous Electrolyte The non-aqueous electrolyte of the present disclosure contains (I) a solute, (II) a non-aqueous organic solvent, (III) a compound represented by the following general formula (1), (IV) a compound represented by the following general formula (4), and (V) at least one compound selected from the group consisting of a nitrate, a compound represented by the following general formula (2), and a compound represented by the following general formula (3), wherein the mass ratio (V) / {(III)+(IV)} of the amount of (V) to the total amount of (III) and (IV) is 0.0040 or more.

[0025]

[0026] In general formula (1), M ａ１＋ is an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a1 represents an integer equal to the valence of the corresponding cation. a1 to d1 represent integers of 1 to 2, and a1×b1=c1×d1 is satisfied. X is a sulfur atom or a phosphorus atom, and when X is a sulfur atom, m is 2, and R ４ is absent, and when X is a phosphorus atom, m is 1. １ ~R ４are each independently an organic group selected from a fluorine atom, an oxygen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond.

[0027]

[0028] In general formula (4), W represents a boron atom, a phosphorus atom, or a silicon atom, n1 is 1 or 2, n2 is 2 or 4, and e is 0 or 1. When e is 0, R ４１ does not exist, and R ４１ The Y written on both sides of ３ and the carbonyl group are directly bonded. ４１ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a halogenated alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a heteroatom in the structure. When n1 is 2 or more, n1 R ４１ may be bonded to each other), and R ４２ represents a halogen atom, Y １ , Y ２ each independently represents an oxygen atom or a sulfur atom; Y ３ represents a carbon atom or a sulfur atom. ３ is 1 when it is a carbon atom, and 1 or 2 when it is a sulfur atom. ａ＋ represents an alkali metal cation, an alkaline earth metal cation, or an onium cation, a represents the valence of the corresponding cation, and a to d are 1 or 2, and a×b=c×d is satisfied.

[0029]

[0030] In general formula (2), p, q, and r each independently represent 0 or 1; ５ ~R ７ are each independently a fluorine atom or a hydrocarbon group having 1 to 20 carbon atoms which may be partially or completely fluorinated, and R ５ and R ６ , R ５ and R ７ , or R ６ and R ７ may be bonded to each other to form a ring structure.

[0031]

[0032] In general formula (3), R ８ , and R ９ are each independently a hydrocarbon group having 1 to 20 carbon atoms.

[0033] The nonaqueous electrolyte solution of the present disclosure contains (III) and (IV), which allows it to exhibit excellent battery performance when used in a nonaqueous electrolyte battery. Furthermore, by further adding (V) such that the mass ratio of the amount of (V) to the total amount of (III) and (IV) is 0.0040 or more, it is possible to suppress coloration during long-term storage at room temperature (25°C) while maintaining excellent battery performance. Each component will be described in detail below.

[0034] <(I) Solute> The solute (I) (also referred to as "(I)") contained in the nonaqueous electrolyte solution of the present disclosure will be described. The solute (I) is not particularly limited, and may be, for example, LiPF ６ , LiBF ４ , LiSbF ６ , LiAsF ６ , LiClO ４ , LiN(FSO ２ ) ２ , LiAlO ２ , LiAlCl ４ , LiCl and LiI, or NaPF ６ , NaBF ４ , NaSbF ６ , NaAsF ６ , NaClO ４ , NaN(FSO ２ )２ , NaAlO ２ , NaAlCl ４ , NaCl, and NaI.

[0035] In the nonaqueous electrolyte solution of the present disclosure, as (I), one type of compound may be used alone, or two or more types of compounds may be mixed in any combination and ratio depending on the application.

[0036] The concentration of (I) relative to the total amount of the nonaqueous electrolyte is not particularly limited. For example, the lower limit of the concentration of (I) may be 0.5 mol / L or more, 0.7 mol / L or more, or 0.9 mol / L or more. The upper limit of the concentration of (I) may be 5 mol / L or less, 4 mol / L or less, or 2 mol / L or less. When two or more types of (I) are used, it is preferable that the total concentration of these solutes is in the above-mentioned range.

[0037] The temperature of the solution when (I) is dissolved in (II) the nonaqueous organic solvent is not particularly limited, but may be −20 to 80° C. or 0 to 60° C. Furthermore, the cation of the solute is more preferably a lithium ion when used in a lithium ion battery, and more preferably a sodium ion when used in a sodium ion battery.

[0038] <Regarding (II) Non-aqueous Organic Solvent> The non-aqueous organic solvent (II) (also referred to as "(II)") contained in the non-aqueous electrolyte solution of the present disclosure will be described. The type of non-aqueous organic solvent (II) is not particularly limited, and any non-aqueous organic solvent can be used. Specific examples of the non-aqueous organic solvent (II) include the following non-aqueous organic solvents. Examples of cyclic esters include cyclic carbonates such as propylene carbonate (hereinafter sometimes referred to as "PC"), ethylene carbonate (hereinafter sometimes referred to as "EC"), fluoroethylene carbonate (hereinafter sometimes referred to as "FEC"), and butylene carbonate, as well as γ-butyrolactone and γ-valerolactone. Note that when the content of the FEC relative to the total amount of the non-aqueous electrolyte solution is 10% by mass or less, it is defined as an "other additive" as described below. Examples of chain esters include chain carbonates such as diethyl carbonate (hereinafter sometimes referred to as "DEC"), dimethyl carbonate (hereinafter sometimes referred to as "DMC"), ethyl methyl carbonate (hereinafter sometimes referred to as "EMC"), and methyl propyl carbonate, as well as methyl acetate, methyl propionate, and ethyl propionate (hereinafter sometimes referred to as "EP"). Examples of cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran, and dioxane. Examples of chain ethers include dimethoxyethane and diethyl ether. Other examples include sulfone compounds and sulfoxide compounds such as dimethyl sulfoxide and sulfolane. Ionic liquids and the like can also be used.

[0039] (II) The nonaqueous organic solvent may contain at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids.

[0040] The cyclic ester contains a cyclic carbonate, and the cyclic carbonate may contain at least one selected from the group consisting of ethylene carbonate, propylene carbonate, and fluoroethylene carbonate, or may contain at least one selected from the group consisting of ethylene carbonate and propylene carbonate.

[0041] The chain ester contains a chain carbonate, and the chain carbonate may contain at least one selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, and methyl propyl carbonate.

[0042] In the nonaqueous electrolyte solution of the present disclosure, as (II), one type of compound may be used alone, or two or more types of compounds may be mixed in any combination and ratio depending on the application.

[0043] The content of the cyclic carbonate is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure. However, when one type is used alone, the content is 3 vol% or more, more preferably 5 vol% or more, based on 100 vol% of the nonaqueous organic solvent. By setting the content within this range, a decrease in electrical conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte can be avoided, and the large-current discharge characteristics, stability with respect to the negative electrode, and cycle characteristics of the nonaqueous electrolyte battery can be easily maintained within good ranges. Furthermore, the content is usually 90 vol% or less, preferably 85 vol% or less, and more preferably 80 vol% or less. Setting the content within this range allows the viscosity of the nonaqueous electrolyte to be within an appropriate range, suppresses a decrease in ionic conductivity, and ultimately facilitates maintaining good load characteristics of the nonaqueous electrolyte battery.

[0044] Additionally, any combination of two or more cyclic carbonates can be used. One preferred combination is a combination of ethylene carbonate and propylene carbonate. In this case, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99:1 to 40:60, and particularly preferably 95:5 to 50:50. Furthermore, the amount of propylene carbonate relative to the total nonaqueous organic solvent is not particularly limited and may be any amount as long as it does not significantly impair the effects of the present disclosure. However, it is usually 1% by volume or more, preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, and more preferably 20% by volume or less. A propylene carbonate content within this range is preferred because it maintains the properties of the combination of ethylene carbonate and dialkyl carbonates while providing even more excellent low-temperature properties.

[0045] The chain ester may be used alone or in any combination and ratio of two or more. The content of the chain ester is not particularly limited, but is typically 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more, based on 100% by volume of the nonaqueous organic solvent. Furthermore, it is typically 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. By setting the content of the chain ester within the above range, the viscosity of the nonaqueous electrolyte can be adjusted to an appropriate range, a decrease in ionic conductivity can be suppressed, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte battery can be easily adjusted to a good range. Furthermore, a decrease in electrical conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte can be avoided, and the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte battery can be easily adjusted to a good range. Furthermore, by combining a specific chain ester with ethylene carbonate at a specific content, battery performance can be significantly improved.

[0046] For example, when dimethyl carbonate and ethyl methyl carbonate are selected as the specific chain esters, the content of ethylene carbonate is not particularly limited and can be any amount as long as it does not significantly impair the effects of the present disclosure, but is usually 5% by volume or more, preferably 10% by volume or more, and usually 45% by volume or less, preferably 40% by volume or less, the content of dimethyl carbonate is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less, and the content of ethyl methyl carbonate is usually 20% by volume or more, preferably 30% by volume or more, and usually 50% by volume or less, preferably 45% by volume or less. By setting the content within the above ranges, the low-temperature deposition temperature of the electrolyte is lowered, while the viscosity of the nonaqueous electrolyte is also lowered, improving ionic conductivity and allowing high input / output even at low temperatures.

[0047] The content of the chain ether is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but is typically 1 vol% or more, preferably 2 vol% or more, more preferably 3 vol% or more, and typically 30 vol% or less, preferably 25 vol% or less, more preferably 20 vol% or less, based on 100 vol% of the nonaqueous organic solvent. When the content of the chain ether is within the above range, it is easy to ensure the effect of improving the degree of lithium ion dissociation of the chain ether and improving ionic conductivity due to reduced viscosity. Furthermore, when the negative electrode active material is a carbonaceous material, the phenomenon of co-insertion of the chain ether with lithium ions can be suppressed, thereby allowing the input / output characteristics and charge / discharge rate characteristics to be within appropriate ranges.

[0048] The content of the sulfone compound is not particularly limited and may be any content as long as it does not significantly impair the effects of the present disclosure, but is usually 0.3 vol% or more, preferably 0.5 vol% or more, more preferably 1 vol% or more, and usually 40 vol% or less, preferably 35 vol% or less, more preferably 30 vol% or less, based on 100 vol% of the nonaqueous organic solvent. If the content of the sulfone compound is within the above range, it is easy to obtain an effect of improving durability such as cycle characteristics and storage characteristics, and it is also possible to keep the viscosity of the nonaqueous electrolyte within an appropriate range, avoid a decrease in electrical conductivity, and keep the input / output characteristics and charge / discharge rate characteristics of the nonaqueous electrolyte battery within appropriate ranges.

[0049] <(III) Compound Represented by General Formula (1)> The compound (III) represented by the following general formula (1) (also referred to as "(III)") contained in the nonaqueous electrolyte solution of the present disclosure will be described.

[0050]

[0051] In general formula (1), M ａ１＋ is an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a1 represents an integer equal to the valence of the corresponding cation. a1 to d1 represent integers of 1 to 2, and a1×b1=c1×d1 is satisfied. X is a sulfur atom or a phosphorus atom, and when X is a sulfur atom, m is 2, and R ４ is absent, and when X is a phosphorus atom, m is 1. １ ~R ４are each independently an organic group selected from a fluorine atom, an oxygen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond.

[0052] In general formula (1), R １ ~R ４ are each independently an organic group selected from a fluorine atom, an oxygen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond. The organic group may contain a substituent within its structure.

[0053] R １ ~R ４ The alkyl group represented by the formula (I) may be linear or branched, and examples thereof include alkyl groups having 1 to 10 carbon atoms and fluorine-containing alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a trifluoromethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3-tetrafluoropropyl group, and a 1,1,1,3,3,3-hexafluoroisopropyl group. １ ~R ４The alkoxy group represented by the formula (I) may be linear or branched, and examples thereof include alkoxy groups having 1 to 10 carbon atoms and fluorine-containing alkoxy groups, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a trifluoromethoxy group, a 2,2-difluoroethoxy group, a 2,2,2-trifluoroethoxy group, a 2,2,3,3-tetrafluoropropoxy group, a 1,1,1-trifluoroisopropoxy group, and a 1,1,1,3,3,3-hexafluoroisopropoxy group.

[0054] R １ ~R ４ The alkenyl group represented by R may be linear or branched, and examples thereof include alkenyl groups having 2 to 10 carbon atoms, such as vinyl, 1-propenyl, 2-propenyl, isopropenyl, 2-butenyl, 3-butenyl, and 1,3-butadienyl, as well as fluorine-containing alkenyl groups. １ ~R ４ The alkenyloxy group represented by the formula (I) may be linear or branched, and examples thereof include alkenyloxy groups having 2 to 10 carbon atoms, such as a vinyloxy group, a 1-propenyloxy group, a 2-propenyloxy group, an isopropenyloxy group, a 2-butenyloxy group, a 3-butenyloxy group, and a 1,3-butadienyloxy group, and fluorine-containing alkenyloxy groups.

[0055] R １ ~R ４ The alkynyl group represented by the formula (R) may be linear or branched, and examples thereof include alkynyl groups having 2 to 10 carbon atoms, such as ethynyl, 2-propynyl, and 1,1-dimethyl-2-propynyl, and fluorine-containing alkynyl groups. １ ~R ４ The alkynyloxy group represented by the formula (I) may be linear or branched, and examples thereof include alkynyloxy groups having 2 to 10 carbon atoms, such as an ethynyloxy group, a 2-propynyloxy group, and a 1,1-dimethyl-2-propynyloxy group, and fluorine-containing alkynyloxy groups.

[0056] R １~R ４ Examples of the cycloalkyl group represented by the formula (R) include cycloalkyl groups having 3 to 10 carbon atoms, such as a cyclopentyl group and a cyclohexyl group, and fluorine-containing cycloalkyl groups. １ ~R ４ Examples of the cycloalkoxy group represented by the formula (I) include cycloalkoxy groups having 3 to 10 carbon atoms, such as a cyclopentyloxy group and a cyclohexyloxy group, and fluorine-containing cycloalkoxy groups.

[0057] R １ ~R ４ Examples of the cycloalkenyl group represented by the formula (R) include cycloalkenyl groups having 3 to 10 carbon atoms, such as a cyclopentenyl group and a cyclohexenyl group, and fluorine-containing cycloalkenyl groups. １ ~R ４ Examples of the cycloalkenyloxy group represented by the formula (I) include cycloalkenyloxy groups having 3 to 10 carbon atoms, such as a cyclopentenyloxy group and a cyclohexenyloxy group, and fluorine-containing cycloalkenyloxy groups.

[0058] R １ ~R ４ Examples of the aryl group represented by R include aryl groups having 6 to 10 carbon atoms, such as a phenyl group, a tolyl group, and a xylyl group, and fluorine-containing aryl groups. １ ~R ４ Examples of the aryloxy group represented by the formula (I) include aryloxy groups having 6 to 10 carbon atoms, such as phenyloxy group, tolyloxy group, and xylyloxy group, and fluorine-containing aryloxy groups.

[0059] R １ ~R ４ are each independently a fluorine atom or an alkoxy group having a fluorine atom, which is preferable because the degree of ionic dissociation is improved due to its strong electron-withdrawing property, thereby increasing the ionic conductivity in the non-aqueous electrolyte. Furthermore, a fluorine atom is even more preferable because the anion size is reduced, thereby improving mobility, thereby significantly increasing the ionic conductivity in the non-aqueous electrolyte. １ ~R ４At least one of these is preferably a fluorine atom.

[0060] Also, R １ ~R ４ The number of carbon atoms is preferably 6 or less. When the number of carbon atoms is 6 or less, the ionic conductivity tends to be relatively high, which is preferable.

[0061] In general formula (1), M ａ１＋ represents an alkali metal cation, an alkaline earth metal cation, or an onium cation. The type of cation is not particularly limited as long as it does not impair the performance of the nonaqueous electrolyte and the nonaqueous electrolyte battery of the present disclosure, and various cations can be selected from the above.

[0062] M ａ１＋ Examples of the alkali metal cation represented by M include a lithium ion, a sodium ion, a potassium ion, a rubidium ion, and a cesium ion. ａ１＋ Examples of the alkaline earth metal cation represented by M include magnesium ion, calcium ion, and barium ion. ａ１＋ Examples of the onium cation represented by the formula (I) include tetraalkylammonium, tetraalkylphosphonium, and imidazolium derivatives. a1 represents the valence of the corresponding cation and may be 1 or 2.

[0063] M ａ１＋ In particular, from the viewpoint of helping ion conduction in a non-aqueous electrolyte battery, lithium ions, sodium ions, potassium ions, tetramethylammonium ions, tetraethylammonium ions, tetrabutylphosphonium ions, etc. are preferred. ａ１＋ When used in a lithium ion battery, the charge carrier is more preferably a lithium ion, and when used in a sodium ion battery, the charge carrier is more preferably a sodium ion.

[0064] The compound represented by the above general formula (1) is preferably any of the compounds represented by the following general formulas (1-1) to (1-5).

[0065]

[0066] In general formulas (1-1) to (1-5), M ａ１＋ is an alkali metal cation, alkaline earth metal cation, or onium cation, and a1 represents an integer equal to the valence of the corresponding cation. a1 to d1 represent integers of 1 or 2, and in general formulas (1-1) to (1-2), a1 = d1 is satisfied, and in general formulas (1-3) to (1-5), a1 × b1 = 2 × d1 is satisfied. R １１ ~R １６ , and R １８ ~R ２３ are each independently an organic group selected from a fluorine atom, an alkoxy group having 1 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond. １７ and R ２４ represents an organic group selected from a fluorine atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond.

[0067] M in general formulas (1-1) to (1-5) ａ１＋ represents M in general formula (1). ａ１＋ The same applies to preferred examples.

[0068] R in general formulas (1-1) to (1-5) １１ ~R １６ , and R １８ ~R ２３As the above, an alkoxy group having 1 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms can be represented by R １ ~R ４ The same groups as those mentioned above can be mentioned as R １１ ~R １６ , and R １８ ~R ２３ are each independently preferably a fluorine atom or an alkoxy group having a fluorine atom, more preferably a fluorine atom. １１ ~R １６ , and R １８ ~R ２３ Preferably, the number of carbon atoms is 6 or less.

[0069] R in general formulas (1-2) and (1-5) １７ and R ２４ As the above, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms are represented by R in general formula (1). １ ~R ４ The same groups as those mentioned above can be mentioned as R １７ and R ２４ is preferably a fluorine atom. １７ and R ２４ Preferably, the number of carbon atoms is 6 or less.

[0070] The compound represented by general formula (1) is preferably a compound represented by the above general formula (1-1) or (1-2), and more preferably a bis(difluorophosphoryl)imide salt or a (fluorosulfonyl)(difluorophosphoryl)imide salt.

[0071] Specific examples of the anion structure of the compound represented by formula (1) are shown below, but the invention is not limited to these.

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] In the nonaqueous electrolyte solution of the present disclosure, as (III), one type of compound may be used alone, or two or more types of compounds may be mixed in any combination and ratio depending on the application.

[0078] In the nonaqueous electrolyte solution of the present disclosure, the content of (III) (also referred to as the "concentration of (III)") relative to the total amount of the nonaqueous electrolyte solution may be 0.01% by mass or more and 10% by mass or less. The lower limit of the concentration of (III) may be 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. The upper limit of the concentration of (III) may be 5% by mass or less, 3.5% by mass or less, or 2.5% by mass or less.

[0079] <(IV) Compound Represented by General Formula (4)> The compound (IV) represented by the following general formula (4) (also referred to as "(IV)") contained in the nonaqueous electrolyte solution of the present disclosure will be described.

[0080]

[0081] In general formula (4), W represents a boron atom, a phosphorus atom, or a silicon atom, n1 is 1 or 2, n2 is 2 or 4, and e is 0 or 1. When e is 0, R ４１ does not exist, and R ４１ The Y written on both sides of ３ and the carbonyl group are directly bonded. ４１represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a halogenated alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a heteroatom in the structure. When n1 is 2 or more, n1 R ４１ may be bonded to each other), and R ４２ represents a halogen atom, Y １ , Y ２ each independently represents an oxygen atom or a sulfur atom; Y ３ represents a carbon atom or a sulfur atom. ３ is 1 when it is a carbon atom, and 1 or 2 when it is a sulfur atom. ａ＋ represents an alkali metal cation, an alkaline earth metal cation, or an onium cation, a represents the valence of the corresponding cation, and a to d are 1 or 2, and a×b=c×d is satisfied.

[0082] In the general formula (4), W represents a boron atom, a phosphorus atom, or a silicon atom, and is preferably a boron atom or a phosphorus atom.

[0083] R ４１ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a halogenated alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These groups may contain a substituent or a heteroatom in their structure. When n1 is 2 or more, the n1 R ４１ may be bonded to each other.

[0084] R ４１ Examples of the alkylene group represented by R include alkylene groups having 1 to 10 carbon atoms, such as methylene, ethylene, propylene, isopropylene, butylene, isobutylene, and pentylene. ４１Examples of halogenated alkylene groups represented by the formula (R) include halogenated alkylene groups having 1 to 10 carbon atoms, such as difluoromethylene, 2,2-difluoroethylene, and 2,2,3,3-tetrafluoropropylene. ４１ Examples of the alkenylene group represented by the formula (R) include alkenylene groups having 2 to 10 carbon atoms, such as a vinylene group, a 1-propenylene group, a 2-propenylene group, an isopropenylene group, a 2-butenylene group, a 3-butenylene group, and a 1,3-butadienylene group. ４１ Examples of the halogenated alkenylene group represented by the formula (I) include halogenated alkenylene groups having 2 to 10 carbon atoms, such as a difluorovinylene group. ４１ Examples of the arylene group represented by the formula (R) include arylene groups having 6 to 20 carbon atoms, such as a phenylene group, a tolylene group, and a xylylene group. ４１ Examples of the halogenated arylene group represented by the formula (I) include halogenated arylene groups having 6 to 20 carbon atoms, such as a fluorinated phenylene group.

[0085] R ４１ As the alkylene group, an alkylene group having 1 to 10 carbon atoms or an alkenylene group having 2 to 10 carbon atoms is preferred, and a methylene group or a vinylene group is more preferred.

[0086] R ４２ Examples of the halogen atom represented by R include a fluorine atom, a chlorine atom, and a bromine atom. ４２ is preferably a fluorine atom.

[0087] Y １ , Y ２ each independently represents an oxygen atom or a sulfur atom, and it is preferable that all of them are oxygen atoms.

[0088] Y ３ represents a carbon atom or a sulfur atom, and is preferably a carbon atom.

[0089] M ａ＋ Examples of the alkali metal cation, alkaline earth metal cation, and onium cation represented by the formula (1) include M ａ１＋The alkali metal cations, alkaline earth metal cations, and onium cations listed above are also included, and the preferred examples are also the same. ａ＋ When used in a lithium ion battery, the charge carrier is more preferably a lithium ion, and when used in a sodium ion battery, the charge carrier is more preferably a sodium ion.

[0090] The compound represented by the general formula (4) is preferably an oxalate salt compound, that is, a compound represented by the following general formula (4-1):

[0091]

[0092] In general formula (4-1), W, n1, n2, R ４２ , M ａ＋ , and a to d represent W, n1, n2, and R in the general formula (4). ４２ , M ａ＋ , and a to d, and preferred examples thereof are also the same.

[0093] Examples of the compound represented by the general formula (4) include difluoro(oxalato)borate, bis(oxalato)borate, tetrafluoro(oxalato)phosphate, difluorobis(oxalato)phosphate, tris(oxalato)phosphate, difluorobis(oxalato)silicate, tetrafluoro(malonato)phosphate, difluoro(sulfoacetato)borate, difluoro(maleato)borate, and difluoro(fumarato)borate. Among these, from the viewpoint of solubility in the electrolyte and thermal stability at high temperatures, at least one salt selected from the group consisting of difluoro(oxalato)borate, bis(oxalato)borate, tetrafluoro(oxalato)phosphate, difluorobis(oxalato)phosphate, and tris(oxalato)phosphate is preferred.

[0094] In the nonaqueous electrolyte solution of the present disclosure, one type of compound may be used alone as (IV), or two or more types of compounds may be mixed in any combination and ratio depending on the application.

[0095] In the nonaqueous electrolyte solution of the present disclosure, the content of (IV) (also referred to as the "concentration of (IV)") relative to the total amount of the nonaqueous electrolyte solution may be 0.01% by mass or more and 10% by mass or less. The lower limit of the concentration of (IV) may be 0.05% by mass or more, 0.1% by mass or more, or 0.5% by mass or more. The upper limit of the concentration of (IV) may be 5% by mass or less, 3.5% by mass or less, or 2.5% by mass or less.

[0096] <(V) At least one compound selected from the group consisting of nitrate, a compound represented by general formula (2), and a compound represented by general formula (3)> The at least one compound (also referred to as "(V)") contained in the nonaqueous electrolyte solution of the present disclosure and selected from the group consisting of nitrate, a compound represented by the following general formula (2), and a compound represented by the following general formula (3) will be described.

[0097] (Nitrate) Examples of the nitrate include nitrates of alkali metals such as lithium ions, sodium ions, potassium ions, rubidium ions, and cesium ions, and nitrates of alkaline earth metals such as magnesium ions, calcium ions, and barium ions. When used in lithium-ion batteries, the nitrate is more preferably lithium nitrate, and when used in sodium-ion batteries, the nitrate is more preferably sodium nitrate.

[0098] (Compound represented by general formula (2))

[0099]

[0100] In general formula (2), p, q, and r each independently represent 0 or 1; ５ ~R ７ are each independently a fluorine atom or a hydrocarbon group having 1 to 20 carbon atoms which may be partially or completely fluorinated, and R ５ and R ６ , R ５ and R ７ , or R ６ and R ７ may be bonded to each other to form a ring structure.

[0101] In formula (2), p, q, and r each independently represent 0 or 1, and preferably all represent 1.

[0102] R ５ ~R ７ R each independently represents a fluorine atom or a hydrocarbon group having 1 to 20 carbon atoms which may be partially or completely fluorinated. ５ ~R ７ Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. The hydrocarbon group having 1 to 20 carbon atoms may contain a substituent in its structure.

[0103] R ５ ~R ７ The alkyl group represented by the formula (I) may be linear or branched, and examples thereof include alkyl groups and fluorine-containing alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a trifluoromethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 2,2,3,3-tetrafluoropropyl group, and a 1,1,1,3,3,3-hexafluoroisopropyl group.

[0104] R ５ ~R ７ The alkenyl group represented by the formula (I) may be linear or branched, and examples thereof include alkenyl groups having 2 to 20 carbon atoms, such as vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 2-butenyl group, 3-butenyl group, and 1,3-butadienyl group, and fluorine-containing alkenyl groups.

[0105] R ５ ~R ７ The alkynyl group represented by the formula (I) may be linear or branched, and examples thereof include alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a 2-propynyl group, and a 1,1-dimethyl-2-propynyl group, and fluorine-containing alkynyl groups.

[0106] R ５ ~R ７ Examples of the cycloalkyl group represented by the formula (I) include cycloalkyl groups having 3 to 20 carbon atoms, such as a cyclopentyl group and a cyclohexyl group, and fluorine-containing cycloalkyl groups.

[0107] R ５ ~R ７ Examples of the cycloalkenyl group represented by the formula (I) include cycloalkenyl groups having 3 to 20 carbon atoms, such as a cyclopentenyl group and a cyclohexenyl group, and fluorine-containing cycloalkenyl groups.

[0108] R ５ ~R ７ Examples of the aryl group represented by the formula (I) include aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a tolyl group, and a xylyl group, and fluorine-containing aryl groups.

[0109] R ５ , R ６ , and R ７ are each independently, from the viewpoint of the coloration suppression effect, preferably an alkyl group having 1 to 20 carbon atoms, a fluorine-containing alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, more preferably a methyl group, an ethyl group, an isopropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, or a phenyl group, still more preferably an ethyl group, an isopropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, or a phenyl group, particularly preferably an isopropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, or a phenyl group, and most preferably a phenyl group.

[0110] The compound represented by the general formula (2) is a compound in which q, r, and s are all 1, and R ５ ~R ７ are preferably all the same hydrocarbon groups having 1 to 20 carbon atoms which may be partially or completely fluorinated. That is, the compound represented by general formula (2) is preferably a compound represented by the following general formula (2-1):

[0111]

[0112] R in general formula (2-1)５ａ ~R ７ａ represent the same hydrocarbon groups having 1 to 20 carbon atoms, some or all of which may be fluorinated.

[0113] R ５ａ ~R ７ａ The hydrocarbon group having 1 to 20 carbon atoms, which may be partially or completely fluorinated, represented by R ５ ~R ７ and preferred examples thereof are hydrocarbon groups having 1 to 20 carbon atoms, which may be partially or completely fluorinated, represented by the formula:

[0114] Examples of compounds represented by general formula (2) are shown below, but the compounds are not limited to these.

[0115]

[0116] (Compound represented by general formula (3))

[0117]

[0118] In general formula (3), R ８ and R ９ are each independently a hydrocarbon group having 1 to 20 carbon atoms. ８ and R ９ Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. The hydrocarbon group having 1 to 20 carbon atoms may contain a substituent in its structure.

[0119] R ８ and R ９ The alkyl group having 1 to 20 carbon atoms, the alkenyl group having 2 to 20 carbon atoms, the alkynyl group having 2 to 20 carbon atoms, the cycloalkyl group having 3 to 20 carbon atoms, the cycloalkenyl group having 3 to 20 carbon atoms, and the aryl group having 6 to 20 carbon atoms represented by R ５ ~R ７ Examples of the groups are as follows: ８ and R ９are each independently preferably an alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 5 to 6 carbon atoms, and even more preferably a methyl group, an ethyl group, an isopropyl group, or a cyclohexyl group. ８ and R ９ may represent the same hydrocarbon group having 1 to 20 carbon atoms.

[0120] R ８ and R ９ From the viewpoint of the coloration suppression effect, it is more preferable that the atom bonded to the nitrogen atom in general formula (3) is a secondary carbon atom, and R ８ and R ９ are particularly preferably all isopropyl groups or all cyclohexyl groups. That is, it is particularly preferred that the compound represented by general formula (3) is at least one selected from the group consisting of N,N'-diisopropylcarbodiimide and N,N'-dicyclohexylcarbodiimide.

[0121] Examples of compounds represented by general formula (3) are shown below, but the compounds are not limited to these.

[0122]

[0123] Among these, from the viewpoint of the coloration suppression effect, (V) is preferably at least one compound selected from the group consisting of nitrates and compounds represented by the above general formula (2), and more preferably a compound represented by the above general formula (2).

[0124] In the nonaqueous electrolyte solution of the present disclosure, one type of compound may be used alone as (V), or two or more types of compounds may be mixed in any combination and ratio depending on the application.

[0125] In the nonaqueous electrolyte solution of the present disclosure, the content of (V) (also referred to as the "concentration of (V)") relative to the total amount of the nonaqueous electrolyte solution may be 0.005% by mass or more and 10% by mass or less. The lower limit of the concentration of (V) may be 0.008% by mass or more, 0.03% by mass or more, or 0.04% by mass or more. The upper limit of the concentration of (V) may be 5% by mass or less, 3% by mass or less, or 2% by mass or less. Note that when (V) contains a nitrate, from the viewpoint of solubility in the nonaqueous electrolyte solution, the content of the nitrate relative to the total amount of the nonaqueous electrolyte solution is preferably 1% by mass or less.

[0126] In the nonaqueous electrolyte solution of the present disclosure, the mass ratio of (V) to the total amount of (III) and (IV), (V) / {(III) + (IV)}, is 0.0040 or more. By setting this ratio to 0.0040 or more, it is possible to obtain a nonaqueous electrolyte solution that can suppress coloration during long-term storage at room temperature (25 ° C.) while maintaining excellent battery performance when used in a nonaqueous electrolyte battery. If the ratio is less than 0.0040, the coloration suppression effect is not fully exerted. From the viewpoint of improving the coloration suppression effect, the ratio is preferably 0.0100 or more, more preferably 0.0500 or more, even more preferably 0.1000 or more, and particularly preferably 0.2500 or more. Furthermore, the upper limit of the ratio is not particularly limited, but from the viewpoint of the efficiency of coloration suppression by adding (V), it is preferably 1.5000 or less. That is, (V) / {(III) + (IV)} is preferably 0.0100 to 1.5000.

[0127] <Regarding Other Additives> The nonaqueous electrolyte solution of the present disclosure is composed of the above-mentioned components as basic constituents, but other additives commonly used in this technical field may be added to the nonaqueous electrolyte solution of the present disclosure in any ratio, as long as the gist of the present disclosure is not impaired. When the nonaqueous electrolyte solution of the present disclosure contains other additives, the content thereof may be 0.01% by mass or more and 10% by mass or less with respect to the total amount of the nonaqueous electrolyte solution.

[0128] Other additives include, for example, cyclohexylbenzene, cyclohexylfluorobenzene, biphenyl, 2-fluorobiphenyl, t-butylbenzene, t-amylbenzene, 2-fluorotoluene, fluorobenzene, vinylene carbonate (hereinafter sometimes referred to as "VC"), vinylene carbonate oligomer (having a number average molecular weight of 170 to 5000 in terms of polystyrene), vinylethylene carbonate, difluoroanisole, fluoroethylene carbonate (hereinafter sometimes referred to as "FEC"), 1,6-diisocyanatohexane, ethynylethylene carbonate, trans-difluoroethylene carbonate, methylpropargyl carbonate, ethylpropargyl carbonate, dipropargyl carbonate, maleic anhydride, succinic anhydride, 1,3-propane sultone ... Lopensultone, butanesultone, dimethylvinylene carbonate, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, methylenemethane disulfonate, dimethylmethane disulfonate, trimethylenemethane disulfonate, methyl methanesulfonate, methanesulfonyl fluoride, ethenesulfonyl fluoride, phenyl difluorophosphate, 1,2-ethanedisulfonic anhydride, trivinylmethylsilane, trivinylfluorosilane, tetravinylsilane, tris(trimethylsilyl)borate, succinonitrile, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(picolinato)phosphate, difluoro(picolinato)borate, 1,3-dimethyl-1,3-divinyl-1,3-di(1,1,1,3,3,3-Hexafluoroisopropyl)disiloxane, lithium fluorosulfate, sodium fluorosulfate, lithium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, lithium nonafluorobutanesulfonate, sodium nonafluorobutanesulfonate, lithium monofluorophosphate, sodium monofluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, sodium bis(pentafluoroethanesulfonyl)imide, (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide lithium, (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide, (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl) Examples of suitable imide include sodium (trifluoromethanesulfonyl)(fluorosulfonyl)imide lithium, (trifluoromethanesulfonyl)(fluorosulfonyl)imide sodium, (pentafluoroethanesulfonyl)(fluorosulfonyl)imide lithium, (pentafluoroethanesulfonyl)(fluorosulfonyl)imide sodium, tris(trifluoromethanesulfonyl)methide lithium, tris(trifluoromethanesulfonyl)methide sodium, carboxylates such as lithium acrylate, sodium acrylate, lithium methacrylate, and sodium methacrylate, and sulfates such as lithium methyl sulfate, sodium methyl sulfate, lithium ethyl sulfate, and sodium ethyl sulfate. While it has been difficult to suppress coloration with compositions containing fluoroethylene carbonate but not (V), it is easier to suppress coloration with compositions containing fluoroethylene carbonate and (V).

[0129] Other additives include, for example, vinylene carbonate, difluorophosphates, fluorosulfonates, 1,3-propene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, ethynylethylene carbonate, trans-difluoroethylene carbonate, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, methylenemethane disulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-di It is also preferable that the compound contains at least one selected from the group consisting of methyl methyl ether, tripropargyl phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(picolinato)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-di(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylsulfamoyl fluoride), tetravinylsilane, trivinylmethylsilane, t-butylbenzene, t-amylbenzene, fluorobenzene, and cyclohexylbenzene.

[0130] In addition, LiN(CF ３ SO ２ ) ２ , LiCF ３ SO ３ , LiC ４ F ９ SO ３ , NaN(CF ３ SO ２ ) ２ , NaCF ３ SO ３ , NaC ４ F ９ SO ３ The content of the nonaqueous electrolyte may be 0.01% by mass or more and 20% by mass or less relative to the total amount of the nonaqueous electrolyte. In addition, the electrolyte for a nonaqueous electrolyte battery may be quasi-solidified with a gelling agent or a crosslinked polymer and used, as in the case of use in a nonaqueous electrolyte battery called a lithium polymer battery.

[0131] Furthermore, when the other additives are ionic salts, the cations thereof are more preferably lithium ions when used in lithium ion batteries, and more preferably sodium ions when used in sodium ion batteries.

[0132] The nonaqueous electrolyte of the present disclosure is suitable for use in nonaqueous electrolyte batteries (preferably nonaqueous electrolyte secondary batteries).

[0133] 2. Regarding the Non-Aqueous Electrolyte Battery The non-aqueous electrolyte battery of the present disclosure includes at least the non-aqueous electrolyte of the present disclosure, a negative electrode, and a positive electrode. It may also include a separator, an exterior body, and the like. The non-aqueous electrolyte battery of the present disclosure preferably includes at least a positive electrode, a negative electrode, a separator, and the non-aqueous electrolyte of the present disclosure. The non-aqueous electrolyte battery of the present disclosure is preferably a non-aqueous electrolyte secondary battery.

[0134] The negative electrode is not particularly limited, but may be made of a material that allows reversible insertion and desorption of alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions.

[0135] For example, in the case of a lithium-ion secondary battery in which the cation is mainly lithium, the negative electrode active material constituting the negative electrode is capable of doping and dedoping lithium ions. For example, carbon materials having a d value of the (002) lattice plane in X-ray diffraction of 0.340 nm or less, carbon materials having a d value of the (002) lattice plane in X-ray diffraction of more than 0.340 nm, oxides of one or more metals selected from Si, Sn, and Al, alloys containing one or more metals selected from Si, Sn, and Al, or alloys of these metals or alloys with lithium, and lithium titanium oxide. These negative electrode active materials can be used alone or in combination of two or more. Lithium metal, metal nitrides, tin compounds, conductive polymers, etc. may also be used.

[0136] For example, in the case of a sodium-ion secondary battery in which the cation is primarily sodium, the negative electrode active material constituting the negative electrode may be sodium metal, an alloy of sodium metal with other metals such as tin, an intermetallic compound of sodium metal with other metals, various carbon materials such as hard carbon, metal oxides such as titanium oxide, metal nitrides, tin (simple substance), tin compounds, activated carbon, conductive polymers, etc. In addition to these, phosphorus (simple substance) such as red phosphorus and black phosphorus, phosphorus compounds such as Co—P, Cu—P, Sn—P, Ge—P, and Mo—P, antimony (simple substance), antimony compounds such as Sb / C and Bi—Sb, etc., may also be used. These negative electrode active materials may be used alone or in combination of two or more types.

[0137] The positive electrode is not particularly limited, but may be made of a material that allows reversible insertion and desorption of alkali metal ions such as lithium ions and sodium ions, or alkaline earth metal ions.

[0138] For example, when the cation is lithium, the positive electrode material is LiCoO ２ , LiNiO ２ , LiMnO ２ , LiMn ２ O ４ Lithium-containing transition metal composite oxides such as those described above, in which a plurality of transition metals such as Co, Mn, and Ni are mixed, those in which a part of the transition metal in the lithium-containing transition metal composite oxide is replaced with a metal other than the transition metal, and LiFePO , which is called olivine. ４ , LiCoPO ４ , LiMnPO ４ transition metal phosphate compounds such as TiO ２ , V ２ O ５ , MoO ３ oxides such as TiS ２ , sulfides such as FeS, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, carbon materials, etc. may also be used. １／３ Mn １／３ Co １／３ ]O ２, Li[Ni ０．４５ Mn ０．３５ Co ０．２ ]O ２ , Li[Ni ０．５ Mn ０．３ Co ０．２ ]O ２ , Li[Ni ０．６ Mn ０．２ Co ０．２ ]O ２ , Li[Ni ０．８ Mn ０．１ Co ０．１ ]O ２ (hereinafter, sometimes referred to as "NCM811"), Li[Ni ０．４９ Mn ０．３ Co ０．２ Zr ０．０１ ]O ２ , Li[Ni ０．４９ Mn ０．３ Co ０．２ Mg ０．０１ ]O ２ , LiNi ０．８ Co ０．２ O ２ , LiNi ０．８５ Co ０．１０ Al ０．０５ O ２ , LiNi ０．８７ Co ０．１０ Al ０．０３ O ２ , LiNi ０．９０ Co ０．０７ Al ０．０３ O ２ , LiNi ０．６ Co ０．３ Al ０．１ O ２、 LiMn １．５ Ni ０．５ O ４ etc.

[0139] For example, when the cation is sodium, the positive electrode material (positive electrode active material) is NaCrO ２ , NaFe ０．５ Co ０．５ O ２ , NaFe ０．４ Mn ０．３ Ni ０．３ O ２ , NaNi ０．５ Ti０．３ Mn ０．２ O ２ , NaNi １／３ Ti １／３ Mn １／３ O ２ , NaNi ０．３３ Ti ０．３３ Mn ０．１６ Mg ０．１７ O ２ , Na ２／３ Ni １／３ Ti １／６ Mn １／２ O ２ , Na ２／３ Ni １／３ Mn ２／３ O ２ sodium-containing transition metal composite oxides such as those described above, in which a plurality of transition metals such as Co, Mn, and Ni are mixed, sodium-containing transition metal composite oxides in which a part of the transition metal is replaced with a metal other than the transition metal, NaFePO ４ , NaVPO ４ F, Na ３ V ２ (P.O. ４ ) ３ , Na ２ Fe ２ (SO ４ ) ３ Polyanion type compounds such as those of the formula Na ａ M ｂ [Fe(CN) ６ ] ｃ (M=Cr, Mn, Fe, Co, Ni, Cu, or Zn, and 0≦a≦2, 0.5≦b≦1.5, 0.5≦c≦1.5), TiO ２ , V ２ O ５ , MoO ３ oxides such as TiS ２ Alternatively, sulfides such as FeS, conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, radical-generating polymers, carbon materials, and the like may be used.

[0140] The positive electrode and negative electrode materials may contain, as a conductive material, acetylene black, ketjen black, carbon fiber, or graphite, and as a binder, polytetrafluoroethylene, polyvinylidene fluoride, SBR resin, or the like, and may further contain an electrode sheet formed into a sheet.

[0141] As a separator for preventing contact between the positive electrode and the negative electrode, a nonwoven fabric or porous sheet made of polypropylene, polyethylene, paper, glass fiber, or the like may be used.

[0142] The above elements are assembled into an electrochemical device having a coin-like, cylindrical, rectangular, aluminum laminate sheet, or other shape.

[0143] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to such examples.

[0144] The compounds of component (III), component (IV), and component (V) used in each of the examples and comparative examples are shown below.

[0145] Component (III)

[0146]

[0147] Component (IV) LiDFOB: lithium difluoro(oxalato)borate LiBOB: lithium bis(oxalato)borate LiTFOP: lithium tetrafluoro(oxalato)phosphate LiDFBOP: lithium difluorobis(oxalato)phosphate LiTOP: lithium tris(oxalato)phosphate

[0148] Component (V) LiNO ３ : Lithium nitrate

[0149]

[0150]

[0151] Comparative Examples 0-1 to 0-8, Reference Examples 0-1 to 0-4 Preparation of Electrolyte Solutions Nos. 0-1 to 0-12 A mixed solvent of ethylene carbonate (hereinafter referred to as "EC"), dimethyl carbonate (hereinafter referred to as "DMC"), and ethyl methyl carbonate (hereinafter referred to as "EMC") in a volume ratio of 3:3:4 was used as (II), and lithium hexafluorophosphate (hereinafter referred to as "LiPF") was added to the solvent as (I). ６ ") was added as (III) to a content of 1.0 mol / L. ２ F) (POF ２ ) or LiN(POF ２ ) ２ The electrolyte solutions Nos. 0-1 to 0-12 were prepared by dissolving (IV) LiBOB, LiDFOB, LiTFOP, LiDFBOP, or LiTOP in the amounts shown in Table 1, and fluoroethylene carbonate (hereinafter referred to as "FEC") in the amounts shown in Table 1. The above preparations were carried out while maintaining the liquid temperature at 25°C.

[0152] [Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-19] <Preparation of Electrolyte Solutions No. 1-1 to 1-36> The above-mentioned components were changed as shown in Table 2, and LiNO was used as (V). ３ Electrolyte solutions No. 1-1 to 1-36 were prepared in the same manner as in the nonaqueous electrolyte solutions shown in Table 1, except that the amounts of

[0153] [Examples 2-1 to 2-22, Comparative Examples 2-1 to 2-27] <Preparation of Electrolyte Solutions No. 2-1 to 2-49> The above-mentioned components were used as shown in Table 3, and P(OPh) was used as (V). ３ , P(OMe) ３ , P(OEt) ３ , P(O-isoPr) ３ , or P(O-HFIP) ３ Electrolyte solutions No. 2-1 to 2-49 were prepared in the same manner as in the nonaqueous electrolyte solutions shown in Table 1, except that the amounts of

[0154] Examples 3-1 to 3-21, Comparative Examples 3-1 to 3-25 Preparation of Electrolyte Solutions Nos. 3-1 to 3-46 Electrolyte solutions Nos. 3-1 to 3-46 were prepared in the same manner as for the nonaqueous electrolyte solutions according to Table 1, except that the above-described components were used as shown in Table 4 and that DIPCDI, DCHCDI, DMCDI, or DECDI was dissolved as (V) in an amount shown in Table 4.

[0155] [25°C Storage Test of Nonaqueous Electrolyte Solutions] The prepared nonaqueous electrolyte solutions were placed in sealed containers and stored in an environment of 25°C to obtain nonaqueous electrolyte solutions according to Examples, Comparative Examples, and Reference Examples.

[0156] [Evaluation of Coloration of Non-aqueous Electrolyte After Storage at 25°C] The degree of coloration of the non-aqueous electrolyte was measured as the Hazen color number (APHA) using a color tester. The APHA values ​​at the initial stage (i.e., after preparation, before storage), after 1 month of storage, after 2 months of storage, and after 4 months of storage are shown in Tables 1 to 4.

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164] Reference Examples 0-1 to 0-3 It was confirmed that electrolyte solution 0-9, which did not contain (III) and (IV), did not discolor even after 4 months of storage at 25° C. Furthermore, it was confirmed that electrolyte solution 0-7, which contained (III) but not (IV), did not discolor even after 4 months of storage at 25° C. Furthermore, it was confirmed that electrolyte solution 0-8, which did not contain (III) but contained (IV), did not discolor even after 4 months of storage at 25° C.

[0165] <Comparative Examples 0-1 to 0-6> On the other hand, it was confirmed that the coloration of the electrolyte solutions 0-1 to 0-6 containing (III) and (IV) progressed upon storage at 25° C., regardless of the type of (IV) or the presence or absence of FEC. This result indicates that the stability of the nonaqueous electrolyte solution containing both (III) and (IV) is inferior to that of a general electrolyte solution that does not contain them (e.g., equivalent to the electrolyte solution composition of the comparative example in Patent Document 4).

[0166] <Reference Example 0-4, Comparative Examples 0-7 to 0-8> The above-mentioned tendency was the same when the type of (III) was changed.

[0167] Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-19 Examples 2-1 to 2-22, Comparative Examples 2-1 to 2-27 Examples 3-1 to 3-21, Comparative Examples 3-1 to 3-25 It was confirmed that when (III) to (V) were contained and the value of (V) / {(III)+(IV)} was 0.0040 or more, discoloration could be suppressed even after 4 months of storage at 25° C. On the other hand, when (III) to (V) were contained but the value of (V) / {(III)+(IV)} was less than 0.0040, discoloration could not be suppressed and actually progressed during storage at 25° C.

[0168] [Battery characteristic evaluation] [Fabrication of non-aqueous electrolyte battery]

[0169] (Preparation of NCM811 positive electrode) LiNi ０．８ Mn ０．１ Co ０．１ O ２ 92.0% by mass of the powder was mixed with 3.5% by mass of polyvinylidene fluoride (hereinafter also referred to as "PVDF") as a binder and 4.5% by mass of acetylene black as a conductive material, and further N-methylpyrrolidone (hereinafter sometimes referred to as "NMP") was added to the LiNi ０．８ Mn ０．１ Co ０．１ O ２ The paste was applied to both sides of an aluminum foil (A1085), dried, pressed, and punched into a 4 cm × 5 cm piece to obtain a test NCM811 positive electrode.

[0170] (Preparation of silicon-containing graphite negative electrode) 85% by mass of artificial graphite powder, 7% by mass of nanosilicon, 3% by mass of conductive material (HS-100 manufactured by Denka), 2% by mass of carbon nanofiber (VGCF manufactured by Showa Denko), 2% by mass of styrene butadiene rubber (hereinafter sometimes referred to as "SBR"), 1% by mass of carboxymethyl cellulose (hereinafter sometimes referred to as "CMC"), and water were mixed to prepare a negative electrode composite paste. This paste was applied to copper foil, dried, pressed, and then punched out to 4.5 cm x 5.5 cm to obtain a test silicon-containing graphite negative electrode.

[0171] (Preparation of Nonaqueous Electrolyte Batteries) In an argon atmosphere with a dew point of −50° C. or lower, a terminal was welded to the above-mentioned NCM811 positive electrode, and then the electrode was sandwiched between two polyethylene separators (5 cm × 6 cm). The outer surface of the separator was then sandwiched between two natural graphite negative electrodes with terminals previously welded, with the negative electrode active material surface facing the positive electrode active material surface. These were then placed in an aluminum laminate bag with an opening on one side, and after vacuum injection of nonaqueous electrolyte, the opening was heat-sealed to prepare aluminum laminate-type nonaqueous electrolyte batteries according to the Examples, Comparative Examples, and Reference Examples shown in Table 5.

[0172] [Evaluation] <Initial Charge / Discharge Test> First, conditioning was performed using the prepared cell at an ambient temperature of 25° C. under the following conditions. That is, in the initial charge / discharge test, the cell was charged at a constant current and constant voltage of 5 mA at an upper charge voltage of 4.2 V, discharged at a constant current of 10 mA to a discharge cut-off voltage of 2.5 V, and then charged at a constant current and constant voltage of 10 mA at an upper charge voltage of 4.2 V, and discharged at a constant current of 10 mA to a discharge cut-off voltage of 2.5 V. This charge / discharge cycle was repeated three times. The discharge capacity in the third cycle was taken as the initial discharge capacity.

[0173] <Cycle Test (60°C)> The nonaqueous electrolyte battery after the initial charge / discharge test was discharged at a constant current of 10 mA to a discharge cutoff voltage of 2.5 V at an ambient temperature of 25°C, and then allowed to stand for 3 hours at an ambient temperature of 60°C. Subsequently, the battery was charged at a constant current and constant voltage of 75 mA to a charge upper limit voltage of 4.2 V, and then discharged at a constant current of 75 mA to a discharge cutoff voltage of 2.5 V. This charge / discharge cycle at 75 mA in a 60°C environment was repeated 500 cycles. Subsequently, the battery was allowed to stand for 3 hours at an ambient temperature of 25°C, and then charged at a constant current and constant voltage of 10 mA to a charge upper limit voltage of 4.2 V, and then discharged at a constant current of 10 mA to a discharge cutoff voltage of 2.5 V. The discharge capacity was recorded as the discharge capacity after the cycle test.

[0174] <Evaluation of Cycle Retention Rate> The capacity retention rate after the cycle test was calculated using the following formula. A larger value indicates better high-temperature cycle characteristics. Capacity retention rate after cycle test (%) = (discharge capacity after cycle test / initial discharge capacity) x 100

[0175] <Internal Resistance Measurement> The nonaqueous electrolyte batteries before and after the 60°C cycle test were charged at a constant current of 10 mA for 150 minutes at an ambient temperature of 25°C, and then discharged at predetermined current values ​​(5 mA, 10 mA, 25 mA, 50 mA, and 100 mA) for 10 seconds. The voltage at the 10th second was measured and plotted against the current value. The least squares method was applied to each plot to obtain an approximate line. The slope of the approximate line was taken as the initial internal resistance and the internal resistance after the cycle test.

[0176] <Evaluation of Increase in Internal Resistance> The increase in internal resistance after the cycle test was calculated using the following formula: Increase in low-temperature internal resistance after cycle test (%) = (internal resistance after cycle test / initial internal resistance) × 100. The smaller this value, the higher the effect of suppressing the increase in internal resistance.

[0177] <Measurement of Gas Generation Amount> The amount of gas generation was evaluated by estimating the increase in cell volume of the nonaqueous electrolyte battery before and after the 60° C. cycle test at an ambient temperature of 25° C. using a buoyancy method with silicone oil. A smaller value indicates a higher gas suppression effect.

[0178]

[0179] In Table 5, the capacity retention rate after the cycle test, the rate of increase in low-temperature internal resistance after the cycle test, and the amount of gas generated are each shown as relative values ​​when the value of Comparative Example 0-1e is taken as 100.

[0180] Compared to Comparative Example 0-1e, which used electrolyte No. 0-1 containing (III) and (IV), Reference Examples 0-1e to 0-3e, which used electrolyte Nos. 0-7 to 0-9, in which either (III) salt or (IV), or neither, was added to the non-aqueous electrolyte, were inferior to Comparative Example 0-1e in all battery characteristics. This result indicates that non-aqueous electrolytes containing (III) and (IV) have excellent battery performance. The same is true for Comparative Example 0-7e, which used electrolyte No. 0-10, in which the type of (III) was changed (comparison between Comparative Example 0-7e and Reference Examples 0-2e to 0-4e). On the other hand, in each example in Table 5, which used a non-aqueous electrolyte containing (V) in electrolyte No. 0-1 or 0-2, no adverse effects on battery performance were observed. This result indicates that (V) has almost no adverse effect on battery performance and can improve the stability of the non-aqueous electrolyte itself.

[0181] According to the present disclosure, it is possible to provide a nonaqueous electrolyte that can exhibit excellent battery performance when used in a nonaqueous electrolyte battery and can suppress coloration during long-term storage at room temperature (25°C), and a nonaqueous electrolyte battery using the nonaqueous electrolyte.

[0182] Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. This application is based on Japanese patent applications filed on August 30, 2023 (Patent Application No. 2023-140511) and February 28, 2024 (Patent Application No. 2024-028755), the contents of which are incorporated herein by reference.

Claims

1. A non-aqueous electrolyte solution comprising: (I) a solute; (II) a non-aqueous organic solvent; (III) a compound represented by the following general formula (1); (IV) a compound represented by the following general formula (4); and (V) at least one compound selected from the group consisting of nitrates, compounds represented by the following general formula (2), and compounds represented by the following general formula (3), wherein the mass ratio of the amount of (V) to the total amount of (III) and (IV), (V) / {(III)+(IV)}, is 0.0040 or more. [In general formula (1), M ａ１＋ is an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a1 is an integer equal to the valence of the corresponding cation. a1 to d1 are integers from 1 to 2, and a1×b1=c1×d1 is satisfied. X is a sulfur atom or a phosphorus atom, and when X is a sulfur atom, m is 2, and R ４ is absent, and when X is a phosphorus atom, m is 1. １ ~R ４ are each independently an organic group selected from a fluorine atom, an oxygen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkynyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkoxy group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, a cycloalkenyloxy group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aryloxy group having 6 to 10 carbon atoms, and the organic group may also contain a fluorine atom, an oxygen atom, or an unsaturated bond.] In the general formula (4), W represents a boron atom, a phosphorus atom, or a silicon atom, n1 represents 1 or 2, n2 represents 2 or 4, and e represents 0 or 1. When e is 0, R ４１ does not exist, and R ４１ The Y written on both sides of ３ and the carbonyl group are directly bonded. ４１ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an alkenylene group having 2 to 10 carbon atoms, a halogenated alkenylene group having 2 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups may contain a heteroatom in the structure. When n1 is 2 or more, n1 R ４１ may be bonded to each other), R ４２ represents a halogen atom; Y １ , Y ２ each independently represents an oxygen atom or a sulfur atom; Y ３ represents a carbon atom or a sulfur atom. f represents Y ３ is 1 when it is a carbon atom, and is 1 or 2 when it is a sulfur atom. ａ＋ represents an alkali metal cation, an alkaline earth metal cation, or an onium cation, and a represents the valence of the corresponding cation. a to d are 1 or 2, and a×b=c×d is satisfied. [In the general formula (2), p, q, and r each independently represent 0 or 1; R ５ ~R ７ each independently represents a fluorine atom or a hydrocarbon group having 1 to 20 carbon atoms which may be partially or completely fluorinated; R ５ and R ６ , R ５ and R ７ , or R ６ and R ７ may be bonded to each other to form a ring structure. [In general formula (3), R ８ , and R ９ are each independently a hydrocarbon group having 1 to 20 carbon atoms.

2. The nonaqueous electrolyte according to claim 1, wherein the ratio (V) / {(III)+(IV)} is 0.0100 to 1.5000.

3. R ​​in the general formula (1) １ ~R ４ The nonaqueous electrolyte according to claim 1 , wherein at least one of the atoms is a fluorine atom.

4. The non-aqueous electrolyte according to claim 1, wherein the compound represented by the general formula (1) is a bis(difluorophosphoryl)imide salt or a (fluorosulfonyl)(difluorophosphoryl)imide salt.

5. The nonaqueous electrolyte according to claim 1, wherein the compound represented by the general formula (4) is an oxalate salt compound.

6. In the general formula (2), q, r, and s are all 1, and R ５ ~R ７ The nonaqueous electrolyte according to claim 1, wherein all of the groups are the same and may be partially or completely fluorinated hydrocarbon groups having 1 to 20 carbon atoms.

7. R in the above general formula (3) ８ , R ９ 2. The nonaqueous electrolyte according to claim 1, wherein the atom bonded to the nitrogen atom as a carbon atom is a secondary carbon atom.

8. The nonaqueous electrolyte according to claim 1, wherein the compound represented by the general formula (3) is at least one selected from the group consisting of N,N'-diisopropylcarbodiimide and N,N'-dicyclohexylcarbodiimide.

9. The non-aqueous electrolyte according to claim 1, wherein the (V) contains a nitrate, and the content of the nitrate relative to the total amount of the non-aqueous electrolyte is 1 mass % or less.

10. The nonaqueous electrolyte according to claim 1, wherein the nonaqueous electrolyte contains fluoroethylene carbonate.

11. The (I) is LiPF ６ , LiBF ４ , LiSbF ６ , LiAsF ６ , LiClO ４ , LiN(FSO ２ ) ２ , LiAlO ２ , LiAlCl ４ 2. The nonaqueous electrolyte according to claim 1, wherein the nonaqueous electrolyte is at least one selected from the group consisting of LiCl and LiI.

12. The above (I) is NaPF ６ , NaBF ４ , NaSbF ６ , NaAsF ６ , NaClO ４ , NaN(FSO ２ ) ２ , NaAlO ２ , NaAlCl ４ 2. The nonaqueous electrolyte according to claim 1, wherein the nonaqueous electrolyte is at least one selected from the group consisting of NaCl and NaI.

13. The nonaqueous electrolyte according to claim 1, wherein (II) includes at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids.

14. The nonaqueous electrolyte according to claim 13, wherein the cyclic ester comprises a cyclic carbonate.

15. The nonaqueous electrolyte according to claim 14, wherein the cyclic carbonate comprises at least one selected from the group consisting of ethylene carbonate and propylene carbonate.

16. The nonaqueous electrolyte according to claim 13, wherein the chain ester comprises a chain carbonate.

17. The nonaqueous electrolyte according to claim 16, wherein the chain carbonate comprises at least one selected from the group consisting of ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, and methyl propyl carbonate.

18. In addition, vinylene carbonate, difluorophosphates, fluorosulfonates, 1,3-propene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, ethynylethylene carbonate, trans-difluoroethylene carbonate, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, methylenemethane disulfonate, 1,2-ethane disulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, tripropargyl fluoride ... The non-aqueous electrolyte solution according to claim 1, which contains at least one selected from the group consisting of phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(picolinato)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-di(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylsulfamoyl fluoride), tetravinylsilane, trivinylmethylsilane, t-butylbenzene, t-amylbenzene, fluorobenzene, and cyclohexylbenzene.

19. A nonaqueous electrolyte battery comprising at least a positive electrode, a negative electrode, a separator, and the nonaqueous electrolyte according to any one of claims 1 to 18.

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