Non-aqueous electrolyte and non-aqueous electrolyte battery

Abstract

Provided are a non-aqueous electrolyte solution and a non-aqueous electrolyte solution battery which are capable of improving low-temperature (-30 DEG C) output characteristics (post-high-temperature storage resistance) after a high-temperature (70 DEG C) storage test and a post-overdischarge capacity retention rate after the high-temperature (70 DEG C) storage test in a well-balanced manner. A non-aqueous electrolyte solution containing: (I-1) a compound represented by general formula [1a] described in the description; and (I-2) at least one compound selected from the group consisting of a compound represented by general formula [1b] and a compound represented by general formula [1b '], and the content of (I-2) in the non-aqueous electrolyte solution is 10-25000 ppm by mass.

Description

Technical Field

[0001] The present disclosure relates to nonaqueous electrolytes and nonaqueous electrolyte batteries. Background Art

[0002] In recent years, the demand for high-capacity, high-power, and high-energy-density batteries, in addition to small, high-energy-density power storage systems for information-related devices and communications equipment, such as personal computers, video cameras, digital cameras, mobile phones, and smartphones, has also rapidly increased. Furthermore, demand is growing for batteries capable of long-term use in large, high-power power storage systems for applications such as power storage. As candidates for these various power storage systems, non-aqueous electrolyte batteries such as lithium-ion batteries, lithium batteries, and lithium-ion capacitors are being actively developed.

[0003] Lithium secondary batteries are mainly composed of a positive electrode, a non-aqueous electrolyte, and a negative electrode. Examples of the negative electrode of a lithium secondary battery include metallic lithium, metal compounds capable of absorbing and releasing lithium (e.g., metal elements, oxides, alloys with lithium, etc.), and carbon materials. In particular, lithium secondary batteries using carbon materials such as coke, artificial graphite, and natural graphite that can absorb and release lithium are 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 have a negative effect on the negative electrode surface due to the non-aqueous organic solvent in the non-aqueous electrolyte being reduced and decomposed during charging. Consequently, the decomposition products and gases produced by the non-aqueous solvent interfere with the original electrochemical reaction of the battery, thereby reducing the cycle characteristics.

[0004] In addition, although lithium secondary batteries using lithium metal, its alloys, metal elements such as silicon and tin, oxides, etc. as negative electrode materials have a high initial capacity, the negative electrode material undergoes micronization during the cycle. Therefore, compared with the negative electrode of carbon material, it is easy to cause reductive decomposition of non-aqueous organic solvents. Therefore, as a result, it is known that the battery's initial irreversible capacity increases, and the battery performance such as the battery capacity and cycle characteristics decreases significantly.

[0005] During the first cycle charge, when lithium cations are embedded in the negative electrode, the negative electrode and the lithium cations, or the negative electrode and the electrolyte solvent, react to form a film composed mainly of lithium oxide, lithium carbonate, or alkyl lithium carbonate on the negative electrode surface. This film on the electrode surface is called the Solid Electrolyte Interface (SEI), which inhibits the reductive decomposition of the solvent and the deterioration of battery performance, and its properties have a significant impact on battery performance.

[0006] As described above, due to the accumulation of decomposition products of the non-aqueous organic solvent, gas generation, adverse effects caused by the pulverization of the negative electrode material, etc., lithium absorption and release into the negative electrode cannot proceed smoothly, resulting in a significant deterioration in battery characteristics such as cycle characteristics.

[0007] In addition, as positive electrodes, for example, LiCoO2, LiMn2O4, LiNiO2, and LiFePO4 are known. When a lithium secondary battery using these materials reaches a high temperature while in a charged state, a portion of the non-aqueous organic solvent in the non-aqueous electrolyte undergoes oxidative decomposition locally at the interface between the positive electrode material and the non-aqueous electrolyte. The resulting decomposition products and gases interfere with the battery's original electrochemical reaction, resulting in reported reductions in battery performance such as cycle characteristics. It is known that a film based on oxidative decomposition products is formed on the surface of the positive electrode, similar to the negative electrode, and this film also plays an important role in suppressing the oxidative decomposition of the solvent and the amount of gas generated.

[0008] As described above, conventional lithium secondary batteries have the following reasons for degrading battery performance: decomposition products and gases generated when the non-aqueous electrolyte decomposes on the positive and negative electrodes hinder the movement of lithium ions, or the battery swells, thereby degrading battery performance.

[0009] In order to overcome these problems and also to improve battery performance represented by long-term durability and output characteristics, it is important to form a SEI with high ion conductivity, low electron conductivity, and long-term stability. The following attempts have been widely made: by adding a small amount (usually more than 0.01 mass% and less than 10 mass%) of a compound called an additive to the non-aqueous electrolyte, a good SEI is actively formed.

[0010] As an attempt to do so, Patent Document 1 discloses a non-aqueous electrolyte for lithium batteries that uses a nitrile compound having a specific structure, thereby suppressing the dissolution of copper components during overdischarge and suppressing an increase in initial resistance.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2021-163684 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] The present inventors have confirmed that the use of the non-aqueous electrolyte solution containing a nitrile compound as described in Patent Document 1 provides high initial input / output characteristics. The present inventors have discovered that this non-aqueous electrolyte solution containing a nitrile compound has room for improvement in low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test, as well as in the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test.

[0016] The present disclosure has been made in view of the above circumstances, and its object is to provide a non-aqueous electrolyte solution and a non-aqueous electrolyte battery that can improve the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test in a well-balanced manner.

[0017] It should be noted that the statement that the non-aqueous electrolyte “can improve in a well-balanced manner the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) and the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test” after a high-temperature (70°C) storage test means that, when the content of (I-2) in the non-aqueous electrolyte is less than 10 ppm by mass, “the high-temperature storage resistance is equal to or greater than that of the non-aqueous electrolyte” and “the discharge capacity retention rate after overdischarge after a high-temperature storage test is superior”.

[0018] Solutions for solving problems

[0019] The above-mentioned problems can be solved by the following configuration. [1]

[0021] A non-aqueous electrolyte comprising:

[0022] (I-1) a compound represented by the following general formula [1a]; and

[0023] (I-2) at least one member selected from the group consisting of a compound represented by the following general formula [1b] and a compound represented by the following general formula [1b′],

[0024] The content of the above-mentioned (I-2) in the non-aqueous electrolyte is 10 to 25,000 ppm by mass.

[0025] M+[XS(=O)2-NC(=0)-R 1 ]-[1a]

[0026] (In the general formula [1a], X represents a halogen atom, R 1 Represents a -CN group or an -OCN group. + represents an alkali metal ion.)

[0027]

[0028] (In general formula [1b], Y represents a boron atom, R 2 represents a fluorine atom. n is 0 to 4, and m is 0 to 2. Q + represents an alkali metal ion, a tetraalkylammonium cation, or a tetraalkylphosphonium cation.)

[0029] Q+[Z]- [1b']

[0030] (In the general formula [1b'], [Z] - The anion portion shown is the structure of the following [1b-1] or a chloride anion. + represents an alkali metal ion, a tetraalkylammonium cation, or a tetraalkylphosphonium cation.)

[0031] [2]

[0033] The non-aqueous electrolyte solution according to [1], wherein the content of the (I-2) in the non-aqueous electrolyte solution is 10 to 8000 ppm by mass. [3]

[0035] The non-aqueous electrolyte solution according to [1] or [2], wherein the content of the (I-1) in the non-aqueous electrolyte solution is 0.01 to 5.00% by mass. [4]

[0037] The non-aqueous electrolyte solution according to any one of [1] to [3], wherein X in the general formula [1a] is a fluorine atom. [5]

[0039] The non-aqueous electrolyte according to any one of [1] to [4], wherein the aforementioned (I-2) is a salt compound comprising at least one counter anion selected from the group consisting of bis(oxalato)borate anions, tetrafluoroborate anions, chloride anions and perchlorate anions, and at least one counter cation selected from the group consisting of lithium cations, sodium cations, potassium cations, tetraalkylammonium cations and tetraalkylphosphonium cations. [6]

[0041] The non-aqueous electrolyte according to any one of [1] to [5], further comprising (II) a solute, wherein the solute is at least one selected from the group consisting of LiPF6, LiSbF6, LiAsF6, LiCF3SO3, LiC4F9SO3, LiAlO2, LiAlCl4 and LiI, or at least one selected from the group consisting of NaPF6, NaSbF6, NaAsF6, NaCF3SO3, NaC4F9SO3, NaAlO2, NaAlCl4 and NaI. [7]

[0043] The non-aqueous electrolyte solution according to any one of [1] to [6], further comprising (III) a non-aqueous organic solvent. [8]

[0045] The non-aqueous electrolyte according to [7], wherein the (III) contains at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids. [9]

[0047] The non-aqueous electrolyte solution according to [7] or [8], wherein the (III) contains a cyclic ester, and the cyclic ester is a cyclic carbonate.

[10]

[0049] The non-aqueous electrolyte solution according to [7] or [8], wherein the (III) contains a chain ester, and the chain ester is a chain carbonate.

[11]

[0051] The non-aqueous electrolyte according to any one of [1] to

[10] , further comprising at least one additive selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, dimethyl dicarbonate, ethynyl ethylene carbonate, trans-difluoroethylene carbonate, difluorobis(oxalato)phosphate, tetrafluorooxalatophosphate, (difluorophosphoryl)(fluorosulfonyl)imide salt, difluorophosphate, fluorosulfonate, nitrate, 1,3-propylene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide, Pentane-2,2-dioxide, methylene methanedisulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, tripropargyl phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(malonic acid)phosphate, tetrafluoro(picolinic acid)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylaminosulfonyl fluoride), tetravinylsilane, trivinylmethylsilane, tert-butylbenzene, tert-amylbenzene, fluorobenzene, and cyclohexylbenzene.

[12]

[0053] A non-aqueous electrolyte battery comprising at least a positive electrode, a negative electrode, a separator, and the non-aqueous electrolyte described in any one of [1] to

[11] .

[0054] Effects of the Invention

[0055] According to the present disclosure, a non-aqueous electrolyte solution and a non-aqueous electrolyte battery can be provided that can improve the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test with good balance. DETAILED DESCRIPTION

[0056] In this specification, “to” is used to mean that the numerical values ​​described before and after it are included as the lower limit and the upper limit.

[0057] Hereinafter, the present disclosure will be described in detail. However, the description of the technical features described below is an example of the embodiment of the present disclosure, and the present disclosure is not limited to these specific contents.

[0058] 1. About non-aqueous electrolyte

[0059] The non-aqueous electrolyte disclosed herein is a non-aqueous electrolyte containing:

[0060] (I-1) a compound represented by the following general formula [1a]; and

[0061] (I-2) at least one member selected from the group consisting of a compound represented by the following general formula [1b] and a compound represented by the following general formula [1b′],

[0062] The content of the above-mentioned (I-2) in the non-aqueous electrolyte is 10 to 25,000 ppm by mass.

[0063] M+[XS(=O)2-NC(=O)-R 1 ]- [1a]

[0064] (In the general formula [1a], X represents a halogen atom, R 1 Represents a -CN group or an -OCN group. + represents an alkali metal ion.)

[0065]

[0066] (In general formula [1b], Y represents a boron atom, R 2 represents a fluorine atom. n is 0 to 4, and m is 0 to 2. Q + represents an alkali metal ion, a tetraalkylammonium cation, or a tetraalkylphosphonium cation.)

[0067] Q+[Z]- [1b']

[0068] (In the general formula [1b'], [Z] - The anion portion shown is the structure of the following [1b-1] or a chloride anion. + represents an alkali metal ion, a tetraalkylammonium cation, or a tetraalkylphosphonium cation.)

[0069]

[0070] Regarding the compound represented by the general formula [1a] (I-1)

[0071] In the above general formula [1a], X represents a halogen atom.

[0072] Examples of the halogen atom represented by X include a fluorine atom, a bromine atom, and an iodine atom. However, from the viewpoint of further lowering the battery resistance, X may be a fluorine atom.

[0073] In the above general formula [1a], R 1 represents a -CN group or a -OCN group.

[0074] In the above general formula [1a], M + Represents an alkali metal ion.

[0075] As M + Examples of the alkali metal ions include lithium ions, sodium ions, and potassium ions, preferably lithium ions or sodium ions. In the case of lithium ion batteries, lithium ions are more preferred, and in the case of sodium ion batteries, sodium ions are more preferred.

[0076] Specific examples of the compound represented by the general formula [1a] include the following compounds, but are not limited to these compounds.

[0077] LiN(SO2F)(COCN)

[0078] LiN(SO2F)(CO(OCN))

[0079] ·NaN(SO2F)(COCN)

[0080] ·NaN(SO2F)(CO(OCN))

[0081] ·LiN(SO2Cl)(COCN)

[0082] LiN(SO2Cl)(CO(OCN))

[0083] ·NaN(SO2Cl)(COCN)

[0084] ·NaN(SO2Cl)(CO(OCN))

[0085] The compound represented by the general formula [1a] may be used alone or in combination of two or more.

[0086] The content of (I-1) (the compound represented by the general formula [1a]) in the non-aqueous electrolyte can be 0.01 to 5.00 mass %, 0.07 to 3.5 mass %, or 0.1 to 2.5 mass % relative to the total amount of the electrolyte. By making the content of the compound represented by the general formula [1a] 0.01 mass % or more, it is easy to obtain the effect of suppressing the initial resistance increase in the non-aqueous electrolyte battery. In addition, by being set to 5.00 mass % or less, the film formed on the electrode does not become excessively thick, which is not easy to cause an increase in resistance.

[0087] The compound represented by the general formula [1a] can be produced by various methods. The production method is not particularly limited. For example, the following method can be used: reacting the corresponding halogenated sulfonyl isocyanate with the corresponding cyanide salt or cyanate salt in the absence of a solvent or in a solvent that does not react with these compounds.

[0088] Regarding (I-2) the compound represented by the general formula [1b] and the compound represented by the general formula [1b']

[0089] (I-2) may be a salt compound comprising at least one counter anion selected from the group consisting of bis(oxalato)borate anions, tetrafluoroborate anions, chloride anions, and perchlorate anions, and at least one counter cation selected from the group consisting of lithium cations, sodium cations, potassium cations, tetraalkylammonium cations, and tetraalkylphosphonium cations.

[0090] Specific examples of the compound represented by the general formula [1b] and the compound represented by the general formula [1b′] include the following compounds, but are not limited to these compounds.

[0091] Lithium bis(oxalato)borate

[0092] Lithium difluorooxalatoborate

[0093] Lithium tetrafluoroborate

[0094] Lithium perchlorate

[0095] Lithium chloride

[0096] Sodium bis(oxalato)borate

[0097] Sodium difluorooxalatoborate

[0098] Sodium tetrafluoroborate

[0099] Sodium perchlorate

[0100] Sodium chloride

[0101] Among them, from the viewpoint of resistance after high-temperature storage, the group consisting of lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, sodium bis(oxalato)borate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium perchlorate, potassium bis(oxalato)borate, potassium difluorooxalatoborate, potassium tetrafluoroborate and potassium perchlorate can be used.

[0102] Lithium and sodium are often used as cations in secondary batteries. Therefore, a cation selected from the group consisting of lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium perchlorate, sodium bis(oxalato)borate, sodium difluorooxalatoborate, sodium tetrafluoroborate, and sodium perchlorate can be used.

[0103] The content of (I-2) in the non-aqueous electrolyte has a lower limit of 10 parts per million (ppm) by mass, can be 30 ppm by mass, or can be 70 ppm by mass, relative to the total amount of the electrolyte. Furthermore, the upper limit of the content of (I-2) relative to the total amount of the electrolyte is 25,000 ppm by mass, can be 15,000 ppm by mass, can be 8,000 ppm by mass, or can be 7,000 ppm by mass. By setting the content of (I-2) to 10 ppm by mass or greater, the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test can be improved without impairing the low-temperature (-30°C) output characteristics (resistance after high-temperature storage). Furthermore, by setting the content to 8,000 ppm by mass or less, both the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) and the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test can be improved.

[0104] The compound represented by the general formula [1b] and the compound represented by the general formula [1b'] can be produced by various methods. There are no particular limitations on the production method. For example, lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium perchlorate, and lithium chloride can use commercial products such as Kishida Chemical Co., Ltd. Lithium difluorooxalatoborate can use commercial products such as Merck Ltd. Sodium salts can also be commercially available products, or those obtained by cation exchange of the above lithium salts can be used.

[0105] Furthermore, when the non-aqueous electrolyte battery is a lithium-ion battery, even if the content of cations other than lithium in the non-aqueous electrolyte is approximately 2000 ppm by mass, the non-aqueous electrolyte of the present disclosure containing the aforementioned (I-1) and a specified amount of the aforementioned (I-2) can achieve the effects of the present disclosure of well-balanced improvement in low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test and discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test. This is advantageous in managing the content of cations other than lithium contained in the raw materials during the preparation of the non-aqueous electrolyte of the present disclosure. From this viewpoint, when the non-aqueous electrolyte battery is a lithium-ion battery, the content of cations other than lithium in the non-aqueous electrolyte can be 2000 ppm by mass or less. It should be noted that, from the viewpoint of the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after the high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after the high-temperature (70°C) storage test, the content of cations other than lithium in the above-mentioned non-aqueous electrolyte is preferably as low as possible, for example, preferably 1000 mass ppm or less, more preferably 500 mass ppm or less, and particularly preferably 300 mass ppm or less.

[0106] It should be noted that, as a non-aqueous electrolyte battery, a lithium ion battery, and a non-aqueous electrolyte containing cations other than lithium in the non-aqueous electrolyte, for example, a non-aqueous electrolyte composition in which the cation species of the solute is lithium, the cation species of (I-1) is lithium, and the cation species of (I-2) is a substance other than lithium can be cited. The content of cations other than lithium in the non-aqueous electrolyte of the lithium ion battery can be obtained by ICP emission spectroscopy.

[0107] Furthermore, when the non-aqueous electrolyte battery is a sodium ion battery, even when the content of cations other than sodium in the non-aqueous electrolyte is approximately 700 ppm by mass, the non-aqueous electrolyte of the present disclosure containing the aforementioned (I-1) and a specified amount of the aforementioned (I-2) can achieve the effects of the present disclosure of well-balanced improvement in low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test and discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test. This is advantageous in managing the content of cations other than sodium contained in the raw materials during the preparation of the non-aqueous electrolyte of the present disclosure. From this viewpoint, when the non-aqueous electrolyte battery is a sodium ion battery, the content of cations other than sodium in the non-aqueous electrolyte can be 700 ppm by mass or less. It should be noted that, if the two viewpoints of the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after the high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after the high-temperature (70°C) storage test are comprehensively considered, the content of cations other than sodium in the above-mentioned non-aqueous electrolyte is preferably as low as possible, for example, preferably 500 mass ppm or less, more preferably 400 mass ppm or less, and particularly preferably 200 mass ppm or less.

[0108] It should be noted that, as a non-aqueous electrolyte battery that is a sodium ion battery and contains cations other than sodium in the non-aqueous electrolyte, for example, a non-aqueous electrolyte composition in which the solute cation species is sodium, the cation species of (I-1) is sodium, and the cation species of (I-2) is a substance other than sodium can be mentioned. The content of cations other than sodium in the non-aqueous electrolyte of the sodium ion battery can be determined by ICP emission spectroscopy.

[0109] About (II) Solute

[0110] The non-aqueous electrolyte of the present disclosure may further include (II) a solute. The (II) solute may be at least one selected from the group consisting of LiPF6, LiSbF6, LiAsF6, LiCF3SO3, LiC4F9SO3, LiAlO2, LiAlCl4, LiC(CF3SO2)3, LiPF3(C3F7)3, LiB(CF3)4, LiBF3(C2F5), and LiI, or at least one selected from the group consisting of NaPF6, NaSbF6, NaAsF6, NaCF3SO3, NaC4F9SO3, NaAlO2, NaAlCl4, NaC(CF3SO2)3, NaPF3(C3F7)3, NaB(CF3)4, NaBF3(C2F5), and NaI.

[0111] There is no particular restriction on the concentration of (II) solute. For example, the lower limit of the solute concentration can be set to more than 0.5 mol / L, can be set to more than 0.7 mol / L, can be set to more than 0.9 mol / L. In addition, the upper limit of the solute concentration can be set to less than 2.5 mol / L, can be set to less than 2.0 mol / L, can be set to less than 1.5 mol / L.

[0112] The liquid temperature when dissolving the solute in the non-aqueous organic solvent is not particularly limited, and may be -20 to 80°C, or 0 to 60°C.

[0113] Regarding (III) non-aqueous organic solvents

[0114] The non-aqueous electrolyte solution of the present disclosure may further include (III) a non-aqueous organic solvent. The type of the non-aqueous organic solvent (III) is not particularly limited, and any non-aqueous organic solvent may be used. Specific examples include the following non-aqueous organic solvents.

[0115] 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.

[0116] Examples of chain esters include diethyl carbonate (hereinafter sometimes referred to as "DEC"), dimethyl carbonate (hereinafter sometimes referred to as "DMC"), and ethyl methyl carbonate (hereinafter sometimes referred to as "EMC"), as well as methyl acetate, methyl propionate, and ethyl propionate (hereinafter sometimes referred to as "EP").

[0117] Examples of the cyclic ether include tetrahydrofuran, 2-methyltetrahydrofuran, and dioxane.

[0118] Examples of the chain ether include dimethoxyethane and diethyl ether.

[0119] Other examples include sulfone compounds such as dimethylsulfoxide and sulfolane, and sulfoxide compounds. Furthermore, ionic liquids and the like are also included.

[0120] The compound (III) may be at least one selected from the group consisting of cyclic esters, chain esters, cyclic ethers, chain ethers, sulfone compounds, sulfoxide compounds, and ionic liquids.

[0121] The above (III) may also include a cyclic ester, wherein the cyclic ester is a cyclic carbonate. Alternatively, the above (III) may include a chain ester, wherein the chain ester is a chain carbonate.

[0122] The non-aqueous organic solvents used in the present disclosure may be used alone or in any combination and ratio depending on the intended use. Among these, from the perspective of electrochemical stability to redox and chemical stability with respect to heat and reaction with the above-mentioned solutes, the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propionate, and ethyl propionate may be particularly useful.

[0123] For example, as nonaqueous organic solvent, if contain more than one in the high cyclic carbonate of dielectric constant and contain more than one in the chain ester beyond the low chain carbonate of liquid viscosity or the chain carbonate, then the ionic conductivity of electrolyte improves.Specifically, can adopt and comprise following combination person.

[0124] (1) Combination of EC and EMC

[0125] (2) Combination of EC and DEC

[0126] (3) Combination of EC, DMC and EMC

[0127] (4) Combination of EC, DEC and EMC

[0128] (5) Combination of EC, EMC and EP

[0129] (6) Combination of PC and DEC

[0130] (7) Combination of PC and EMC

[0131] (8) Combination of PC and EP

[0132] (9) Combination of PC, DMC and EMC

[0133] (10) Combination of PC, DEC and EMC

[0134] (11) Combination of PC, DEC and EP

[0135] (12) Combination of PC, EC and EMC

[0136] (13) Combination of PC, EC, DMC and EMC

[0137] (14) Combination of PC, EC, DEC and EMC

[0138] (15) Combination of PC, EC, EMC and EP

[0139] (16) Combination of EC, FEC, DMC and EMC

[0140] (17) Combination of EC, PC, FEC and EMC

[0141] (18) Combination of EC, PC, FEC, DMC and EMC

[0142] (19) Combination of EC, PC, FEC, DEC and EMC

[0143] About other additives

[0144] The above is a description of the basic structure of the non-aqueous electrolyte solution of the present disclosure. However, additives commonly used in the non-aqueous electrolyte solution of the present disclosure may be added at any ratio as long as the gist of the present disclosure is not impaired.

[0145] The non-aqueous electrolyte solution of the present invention may further contain, as other additives, vinylene carbonate (hereinafter sometimes referred to as "VC"), vinylene carbonate oligomers (polystyrene-equivalent number average molecular weight of 170 to 5000), vinyl ethylene carbonate, fluoroethylene carbonate (hereinafter sometimes referred to as "FEC"), dimethyl dicarbonate, ethynyl ethylene carbonate, trans-difluoroethylene carbonate, dimethyl vinylene carbonate, difluorobis(oxalato)phosphate, tetrafluorooxalatophosphate, (difluorophosphoryl)(fluorosulfonyl)imide salt, difluorophosphate, fluorosulfonate, nitrate, 1,3-propylene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3, Compounds having overcharge prevention effects, negative electrode coating formation effects, and positive electrode protection effects, such as 2-dioxathiolane-2,2-dioxide, methylene methanedisulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, tripropargyl phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(malonic acid)phosphate, tetrafluoro(picolinic acid)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylaminosulfonyl fluoride), tetravinylsilane, trivinylmethylsilane, tert-butylbenzene, tert-amylbenzene, fluorobenzene, cyclohexylbenzene, biphenyl, and difluoroanisole.

[0146] It should be noted that FEC can also be used as the non-aqueous organic solvent. If the content in the electrolyte is 2% by mass or less, it can function as an additive and can therefore also be used as another additive.

[0147] Furthermore, carboxylates such as lithium acrylate, sodium acrylate, lithium methacrylate, and sodium methacrylate, and sulfate esters such as lithium methyl sulfate, sodium methyl sulfate, lithium ethyl sulfate, and sodium methyl sulfate may also be contained.

[0148] Furthermore, as in the case of using the non-aqueous electrolyte battery called a lithium polymer battery, the non-aqueous electrolyte can be pseudo-solidified using a gelling agent or a cross-linked polymer.

[0149] The above-mentioned other additives may contain at least one additive selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, dimethyl dicarbonate, ethynyl ethylene carbonate, trans-difluoroethylene carbonate, difluorobis(oxalato)phosphate, tetrafluorooxalatophosphate, (difluorophosphoryl)(fluorosulfonyl)imide salt, difluorophosphate, fluorosulfonate, nitrate, 1,3-propylene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane-2,2-dioxide. dioxide, methylene methanedisulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, tripropargyl phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(malonic acid)phosphate, tetrafluoro(picolinic acid)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylaminosulfonyl fluoride), tetravinylsilane, trivinylmethylsilane, tert-butylbenzene, tert-amylbenzene, fluorobenzene, and cyclohexylbenzene.

[0150] When the non-aqueous electrolyte solution of the present embodiment contains the above-mentioned other additives, the content thereof can be 0.01% by mass or more and 5.00% by mass or less relative to the total amount of the non-aqueous electrolyte solution.

[0151] The non-aqueous electrolyte disclosed herein is suitable for use in non-aqueous electrolyte batteries (preferably non-aqueous electrolyte secondary batteries).

[0152] 2. About non-aqueous electrolyte batteries

[0153] The non-aqueous electrolyte battery of the present disclosure comprises at least the non-aqueous electrolyte of the present disclosure, a negative electrode, and a positive electrode, and may further comprise a separator, an outer shell, and the like.

[0154] The nonaqueous electrolyte battery of the present disclosure preferably includes at least a positive electrode, a negative electrode, a separator, and the nonaqueous electrolyte of the present disclosure.

[0155] The non-aqueous electrolyte battery disclosed herein is preferably a non-aqueous electrolyte secondary battery.

[0156] The negative electrode is not particularly limited, and a material that can reversibly intercalate and deintercalate alkali metal ions represented by lithium ions and sodium ions, or alkaline earth metal ions can be used.

[0157] 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 a material capable of being doped / dedoped with lithium ions. For example, a material containing at least one selected from the following substances can be mentioned: a carbon material having a d value of 0.340 nm or less in the (002) plane of the lattice in X-ray diffraction, a carbon material having a d value of more than 0.340 nm in the (002) plane of the lattice in X-ray diffraction, an oxide of one or more metals selected from Si, Sn, and Al, an alloy containing one or more metals selected from Si, Sn, and Al, or an alloy 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. In addition, lithium metal, metal nitrides, tin compounds, conductive polymers, etc. can also be used.

[0158] In addition, as the negative electrode active material, a material containing Si and / or Si metal oxide and a carbon material can be suitably mentioned. The above-mentioned Si is silicon metal. In addition, the Si metal oxide can be a compound shown as SiOx (x is a value of 0.5 to 1.5). With respect to the total content of Si and / or Si metal oxide contained in the negative electrode active material at this time, when the total amount of the above-mentioned Si and / or Si metal oxide and carbon material contained in the negative electrode active material is set to 100 mass%, it can be set to 0.1 to 50 mass%, preferably 0.1 to 30 mass%. As the above-mentioned carbon material, graphite is preferred, and various artificial graphites, natural graphites, and hard carbon (non-graphitizable carbon) can be used. Since graphite has very little change in crystal structure accompanying the storage and release of lithium, high energy density and excellent cycle characteristics can be obtained. The shape of graphite can be any of fibrous, spherical, granular or scaly. In addition, amorphous carbon and graphite covered with amorphous carbon on the surface are more preferred because the reactivity of the material surface with the electrolyte is reduced.

[0159] These negative electrode active materials may be used alone or in combination of two or more.

[0160] For example, in the case of a sodium ion secondary battery in which the cation is mainly sodium, as the negative electrode active material constituting the negative electrode, sodium metal, alloys of sodium metal and other metals such as tin, intermetallic compounds of sodium metal and other metals, various carbon materials represented by hard carbon, metal oxides such as titanium oxide, metal nitrides, tin (elemental substance), tin compounds, activated carbon, conductive polymers, etc. can also be used. In addition to these, phosphorus (elemental substance) such as red phosphorus and black phosphorus, phosphorus compounds such as Co-P, Cu-P, Sn-P, Ge-P, Mo-P, antimony (elemental substance), antimony compounds such as Sb / C and Bi-Sb, etc. can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0161] The positive electrode is not particularly limited, and a material capable of reversibly intercalating and deintercalating alkali metal ions or alkaline earth metal ions, typified by lithium ions and sodium ions, can be used.

[0162] For example, when the cation is lithium, as the positive electrode material, lithium-containing transition metal composite oxides such as LiCoO2, LiNiO2, LiMnO2, and LiMn2O4 can be used; these lithium-containing transition metal composite oxides are formed by mixing multiple transition metals such as Co, Mn, and Ni; and these lithium-containing transition metal composite oxides are formed by replacing part of the transition metal with a metal other than a transition metal. Specifically, the following can be mentioned: Li[Ni 1 / 3 Mn 1 / 3 Co 1 / 3 ]O2、Li[Ni 0.45 Mn 0.35 Co 0.2 ]O2、Li[Ni 0.5 Mn 0.3 Co 0.2 ]O2、Li[Ni 0.6 Mn 0.2 Co 0.2 ]O2、Li[Ni 0.8 Mn 0.1 Co 0.1 ]O2 (hereinafter sometimes referred to as "NCM811"), Li[Ni 0.49 Mn 0.3 Co 0.2 Zr 0.01 ]O2、Li[Ni 0.49 Mn 0.3 Co 0.2 Mg 0.01 ]O2、LiNi 0.8 Co 0.2 O2、LiNi 0.85 Co 0.10 Al 0.05 O2、LiNi 0.87 Co 0.10 Al 0.03 O2、LiNi 0.90 Co 0.07 Al 0.03 O2、LiNi 0.6 Co 0.3 Al 0.1 O2、LiNi 0.5 Mn 1.5 O4、LiNi 0.5 Mn 0.5 O2、LiNi 0.1 Mn 1.9 O4、LiCo 0.5Mn 0.5 O2, 0.5[LiNi 0.5 Mn 0.5 O2]·0.5[Li2MnO3]、0.5[LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2]·0.5[Li2MnO3]、0.5[LiNi 0.375 Co 0.25 Mn 0.375 O2]·0.5[Li2MnO3]、0.5[LiNi 0.375 Co 0.125 Fe 0.125 Mn 0.375 O2]·0.5[Li2MnO3]、0.45[LiNi 0.375 Co 0.25 Mn 0.375 O2]·0.10[Li2TiO3]·0.45[Li2MnO3], etc.

[0163] In addition, phosphate compounds of transition metals such as LiFePO4, LiCoPO4, LiMnPO4, etc., which are called olivine, oxides such as TiO2, V2O5, MoO3, sulfides such as TiS2, FeS, or conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, free radical-generating polymers, carbon materials, etc. can also be used.

[0164] For example, when the cation is sodium, NaCrO2, NaFe 0.5 Co 0.5 O2、NaFe 0.4 Mn 0.3 Ni 0.3 O2、NaNi 0.5 Ti 0.3 Mn 0.2 O2、NaNi 1 / 3 Ti 1 / 3 Mn 1 / 3 O2、NaNi 0.33 Ti 0.33 Mn 0.16 Mg 0.17 O2、Na 2 / 3 Ni 1 / 3 Ti 1 / 6 Mn 1 / 2 O2、Na 2 / 3 Ni 1 / 3 Mn 2 / 3O2 and other sodium-containing transition metal composite oxides; these sodium-containing transition metal composite oxides are mixed with a variety of transition metals such as Co, Mn, Ni; these sodium-containing transition metal composite oxides are partially replaced by metals other than other transition metals; NaFePO4, NaVPO4F, Na3V2(PO4)3, Na2Fe2(SO4)3 and other polyanionic compounds; composition formula Na a M b [Fe(CN)6] c Sodium salts of the Prussian blue analogues shown (M represents Cr, Mn, Fe, Co, Ni, Cu or Zn, 0≤a≤2, 0.5≤b≤1.5, 0.5≤c≤1.5); oxides such as TiO2, V2O5, MoO3; sulfides such as TiS2, FeS; or conductive polymers such as polyacetylene, polyparaphenylene, polyaniline, and polypyrrole, activated carbon, free radical-generating polymers, carbon materials, etc.

[0165] Acetylene black, Ketjen black, carbon fiber, or graphite can be added to the positive and negative electrode materials as conductive materials, and polytetrafluoroethylene, polyvinylidene fluoride, or SBR resin can be added as a binder. In addition, electrode sheets formed into sheets can also be used.

[0166] As a separator for preventing contact between the positive electrode and the negative electrode, a nonwoven fabric or a porous sheet made of polypropylene, polyethylene, paper, glass fiber, or the like can be used.

[0167] The above elements are assembled into electrochemical devices in the shape of coins, cylinders, squares, or aluminum laminates.

[0168] Example

[0169] Hereinafter, the present disclosure will be specifically described based on Examples, but the present disclosure is not limited to these Examples.

[0170] <Synthesis Example 1> LiN(SO2F)(COCN)

[0171] Synthesis of compound (LiN(SO2F)(COCN))

[0172] In a 100 ml eggplant-shaped flask, 40 g of acetonitrile (MeCN), 5 g (50 mmol) of aminosulfonyl fluoride, and 2.5 g (50 mmol) of sodium cyanide were placed, followed by the slow addition of 5.5 g (56 mmol) of phosgene. Stirring was performed at or below 40°C for 1 hour, followed by concentration. Subsequently, 0.4 g (50 mmol) of lithium hydride was added, followed by further stirring for 1 hour. Insoluble matter was removed by filtration, and the filtrate was concentrated to yield 7.6 g of the compound (LiN(SO2F)(COCN)) (95% recovery).

[0173] <Synthesis Example 2>LiN(SO2F)(CO(OCN))

[0174] Synthesis of the compound (LiN(SO2F)(CO(OCN)))

[0175] In a 100 ml eggplant-shaped flask, 40 g of MeCN, 5 g (50 mmol) of aminosulfonyl fluoride, and 3.3 g (50 mmol) of sodium cyanate were placed, followed by the slow addition of 5.5 g (56 mmol) of phosgene. Stirring was performed at or below 40°C for 1 hour, followed by concentration. Subsequently, 0.4 g (50 mmol) of lithium hydride was added, followed by further stirring for 1 hour. Insoluble matter was removed by filtration, and the filtrate was concentrated to yield 7.9 g of the compound (LiN(SO2F)(CO(OCN))) (90% recovery).

[0176] The Li salt of bis(oxalato)borate anion (also referred to as "BOB"), and the Li, Na, and K salts of BF4 and ClO4 were purchased from Kishida Chemical Co., Ltd. The Na and K salts of BOB were obtained by cation exchange of the Li salt of BOB.

[0177] Preparation of non-aqueous electrolyte (NCM811 cathode / silicon-containing graphite anode)

[0178] A non-aqueous electrolyte R1-1 of Comparative Example 1-1 was prepared by using a mixed solvent of ethylene carbonate (hereinafter also referred to as "EC"), fluoroethylene carbonate (hereinafter also referred to as "FEC"), dimethyl carbonate (hereinafter also referred to as "DMC"), and ethyl methyl carbonate (hereinafter also referred to as "EMC") at a volume ratio of EC:FEC:DMC:EMC=3:0.2:3:3.8 as a non-aqueous organic solvent. In this solvent, lithium hexafluorophosphate (hereinafter also referred to as "LiPF6") as a solute was dissolved so that its content in the non-aqueous electrolyte solution became 1.00 mol / L. Furthermore, LiN(SO2F)(COCN) as (I-1) was dissolved so that its content (concentration) in the non-aqueous electrolyte solution became 0.05 mass %. It should be noted that the above preparation was carried out while maintaining the liquid temperature at 25°C. In addition, except changing the type and content (concentration) of (I-1) and the type and content (concentration) of (I-2), the components were dissolved in the same manner as above to prepare non-aqueous electrolyte solutions of Examples and Comparative Examples described in Tables 1 to 16 below.

[0179] Preparation of non-aqueous electrolyte (LFP cathode / natural graphite anode)

[0180] A mixed solvent consisting of EC, FEC, DMC, and EMC at a volume ratio of EC:FEC:DMC:EMC = 3:0.2:3:3.8 was used as a non-aqueous organic solvent. LiPF6 as a solute was dissolved in this solvent to a content of 1.00 mol / L in the non-aqueous electrolyte solution. Furthermore, vinylene carbonate (hereinafter also referred to as "VC") was dissolved to a content of 0.5% by mass, and LiN(SO2F)(COCN) as (I-1) was dissolved to a content (concentration) of 0.05% by mass in the non-aqueous electrolyte solution to prepare the non-aqueous electrolyte solution Ra1-1 of Comparative Example a1-1. The above preparation was performed while maintaining the solution temperature at 25°C. The components were dissolved in the same manner as above, except that the type and content (concentration) of (I-1) and the type and content (concentration) of (I-2) were changed, to prepare the non-aqueous electrolyte solutions of the Examples and Comparative Examples described in Tables 23 to 38 below.

[0181] (Production of NCM811 positive electrode)

[0182] At 92.0 mass% LiNi 0.8 Mn 0.1 Co 0.1 O2 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 then added with respect to LiNi 0.8 Mn 0.1 Co 0.1 A positive electrode composite material paste was prepared using 45% N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") containing the combined weight of O2 powder, binder, and conductive material. This paste was applied to both sides of aluminum foil (A1085), dried, pressed, and then punched into 4 cm x 5 cm pieces to produce the NCM811 positive electrode for testing.

[0183] (Production of LFP positive electrode)

[0184] A positive electrode composite paste was prepared by mixing 92.0% LiFePO4 powder with 3.5% PVDF as a binder and 4.5% acetylene black as a conductive material. Furthermore, 48% NMP was added to the total weight of the LiFePO4 powder, binder, and conductive material. This paste was applied to both sides of aluminum foil (A1085), dried, pressed, and then punched into 4 cm × 5 cm pieces to produce the LFP positive electrode for testing.

[0185] (Production of natural graphite negative electrode)

[0186] A negative electrode composite material paste was prepared by mixing 92% by mass of natural graphite powder, 3% by mass of a conductive material (HS-100 manufactured by Denka Company Limited), 2% by mass of carbon nanofibers (VGCF manufactured by Showa Denko), 2% by mass of styrene-butadiene rubber (hereinafter referred to as "SBR"), and 1% by mass of sodium carboxymethylcellulose (hereinafter referred to as "CMC") with water. This paste was applied to copper foil, dried, pressed, and then punched into 4.5 cm x 5.5 cm pieces to produce a natural graphite negative electrode for testing.

[0187] (Fabrication of Silicon-Containing Graphite Anode)

[0188] A negative electrode composite material paste was prepared by mixing 85% artificial graphite powder with 7% nanosilicon, 3% conductive material (HS-100 manufactured by Denka Company Limited), 2% carbon nanofiber (VGCF manufactured by Showa Denko), 2% SBR, 1% CMC, and water. This paste was applied to copper foil, dried, pressed, and then punched into 4.5 cm x 5.5 cm pieces to produce the silicon-containing graphite negative electrode used in the experiment.

[0189] (Manufacturing of non-aqueous electrolyte batteries)

[0190] In an argon atmosphere with a dew point below -50°C, terminals were welded to the NCM811 positive electrode. The electrodes were then sandwiched on either side with two polyethylene separators (5 cm x 6 cm). Furthermore, two silicon-containing graphite negative electrodes, pre-welded with terminals, were sandwiched on the outside, with the negative electrode active material surface facing the positive electrode active material surface. These electrodes were then placed in an aluminum laminate bag with one opening, and the non-aqueous electrolyte solution prepared above was vacuum-injected. The opening was then sealed with heat. This produced the aluminum laminate non-aqueous electrolyte batteries (NCM811 positive electrode / silicon-containing graphite negative electrode) described in Tables 1 to 16, which are described below.

[0191] In the Examples and Comparative Examples in Tables 23 to 38, nonaqueous electrolyte batteries (LFP positive electrode / natural graphite negative electrode) were prepared in the same manner as above, using an LFP positive electrode as the positive electrode and a natural graphite negative electrode as the negative electrode.

[0192] Evaluation of Low-Temperature (-30°C) Output Characteristics (Resistance after High-Temperature Storage) after a High-Temperature (70°C) Storage Test (NCM811 Cathode / Silicon-Containing Graphite Anode)

[0193] Each non-aqueous electrolyte battery (battery cell) produced as described above was allowed to stand at an ambient temperature of 25°C for 12 hours (immersion time: 12 hours), and then conditioned under the following conditions at an ambient temperature of 25°C. Specifically, as the initial charge and discharge cycle, constant current and constant voltage charging was performed at a charge upper limit voltage of 4.3V and a 0.1C rate (9 mA), followed by constant current discharge at a 0.2C rate until the discharge end voltage reached 2.7V. Subsequently, constant current and constant voltage charging was performed at a charge upper limit voltage of 4.3V and a 0.2C rate, followed by constant current discharge at a 0.2C rate until the discharge end voltage reached 2.7V. This charge and discharge cycle was repeated three times.

[0194] Furthermore, a storage test was conducted under the following conditions: the battery cells subjected to the above conditioning were charged at a constant current and constant voltage at a charge upper limit voltage of 4.3 V and a rate of 0.2 C, and stored at 70° C. for one week.

[0195] After implementing the above-mentioned storage test, the battery was discharged at a constant current rate of 0.2C at an ambient temperature of 25°C until the discharge end voltage was 2.7V, and then charged at a constant current constant voltage rate of 0.2C using the constant current constant voltage method until the charge upper limit voltage was 4.3V. The battery was discharged at a constant current rate of 5C at an ambient temperature of -30°C until the discharge end voltage was 2.7V, and the discharge capacity at this time (-30°C discharge capacity) was measured.

[0196] Note that each table shows the relative capacity of each Example / Comparative Example, with the capacity of Comparative Example 0-1, which used the non-aqueous electrolyte R0-1 not containing (I-1) and (I-2), being set to 100. A larger value indicates a greater discharge capacity at low temperature after high-temperature storage, that is, a lower resistance after high-temperature storage.

[0197] <Evaluation of discharge capacity retention after overdischarge (NCM811 positive electrode / silicon-containing graphite negative electrode)>

[0198] Each battery cell subjected to the high-temperature (70°C) storage test described above was subjected to a charge cycle of three times at an ambient temperature of 25°C, using a constant-current, constant-voltage charge cycle with a charge upper limit voltage of 4.3V and a 0.2C rate. The battery cells were then discharged at a 0.2C rate and a constant current until the discharge cutoff voltage reached 2.7V. The third discharge capacity was used as the capacity before the overdischarge test.

[0199] After the above-described operation, the discharged battery cell was further discharged at a constant resistance of 75Ω to 0V, thereby creating an overdischarge state, and then left at an ambient temperature of 25°C for 3 days. After this period, the battery cell was again charged at a constant current and constant voltage at a charge upper limit voltage of 4.3V and a 0.2C rate at an ambient temperature of 25°C. It was then discharged at a constant current rate of 0.2C to a discharge end voltage of 2.7V. The discharge capacity at this point (capacity after overdischarge test) was measured, and the capacity retention rate relative to the capacity before the overdischarge test (discharge capacity retention rate after overdischarge) was calculated using the following formula. It should be noted that the "discharge capacity retention rate after overdischarge" is the relative value of the capacity retention rate of each Example / Comparative Example, when the capacity retention rate of Comparative Example 0-1 is set to 100, as shown in each table.

[0200] Discharge capacity retention rate after over-discharge (%) = (capacity after over-discharge test / capacity before over-discharge test) × 100

[0201] In each table, "E1" indicates the discharge capacity at low temperature (-30°C discharge capacity) after high-temperature storage (relative value), and "E2" indicates the discharge capacity retention rate after overdischarge (relative value).

[0202] [Table 1]

[0203]

[0204] [Table 2]

[0205]

[0206] [Table 3]

[0207]

[0208] [Table 4]

[0209]

[0210] [Table 5]

[0211]

[0212] [Table 6]

[0213]

[0214] [Table 7]

[0215]

[0216] [Table 8]

[0217]

[0218] [Table 9]

[0219]

[0220] [Table 10]

[0221]

[0222] [Table 11]

[0223]

[0224] [Table 12]

[0225]

[0226] [Table 13]

[0227]

[0228] [Table 14]

[0229]

[0230] [Table 15]

[0231]

[0232] [Table 16]

[0233]

[0234] Tables 1 to 16 show that, when compared under the same conditions of type and concentration of (I-1), the nonaqueous electrolytes of Examples can improve E1 and E2 in a well-balanced manner compared to the nonaqueous electrolytes of Comparative Examples.

[0235] Furthermore, examples with a non-aqueous electrolyte solution containing (I-2) of 10 to 15,000 ppm by mass showed further balanced improvements in E1 and E2. "Further balanced improvements in E1 and E2" refer to the fact that, for a non-aqueous electrolyte solution containing (I-2) of less than 10 ppm by mass, both "equivalent or better resistance after high-temperature storage" and "better discharge capacity retention after overdischarge after a high-temperature storage test" were achieved.

[0236] Next, in order to examine the influence of the content of cations other than lithium in the non-aqueous electrolyte when the non-aqueous electrolyte battery is a lithium ion battery, the contents shown in Tables 17 to 22 below were extracted from the above-mentioned Examples and Comparative Examples, and the contents (mass ppm) of cations other than lithium in the non-aqueous electrolyte were determined by ICP emission spectroscopy.

[0237] [Table 17]

[0238]

[0239] [Table 18]

[0240]

[0241] [Table 19]

[0242]

[0243] [Table 20]

[0244]

[0245] [Table 21]

[0246]

[0247] [Table 22]

[0248]

[0249] According to Tables 17 to 22, when compared under the conditions where the type and concentration of (I-1) are the same and the type of anion of (I-2) is the same, it can be seen that the lower the content of cations other than lithium in the non-aqueous electrolyte, the more balanced the improvement in the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after the high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after the high-temperature (70°C) storage test.

[0250] <Evaluation of Low-Temperature (-30°C) Output Characteristics (Resistance after High-Temperature Storage) after a High-Temperature (70°C) Storage Test (LFP Positive Electrode / Natural Graphite Negative Electrode)>

[0251] Each non-aqueous electrolyte battery (battery cell) produced as described above was allowed to stand at an ambient temperature of 25°C for 12 hours (immersion time: 12 hours), and then conditioned under the following conditions at an ambient temperature of 25°C. That is, as the initial charge and discharge, constant current and constant voltage charging was performed at a charge upper limit voltage of 3.5V and a 0.1C rate (9mA), and then discharged at a constant current rate of 0.2C until the discharge end voltage reached 2.0V. Thereafter, constant current and constant voltage charging was performed at a charge upper limit voltage of 3.5V and a 0.2C rate, and then discharged at a constant current rate of 0.2C until the discharge end voltage reached 2.0V. This charge and discharge cycle was repeated three times.

[0252] Furthermore, a storage test was conducted under the following conditions: the battery cells subjected to the above conditioning were charged at a constant current and constant voltage at a charge upper limit voltage of 3.5 V and a rate of 0.2 C, and stored at 70° C. for one week.

[0253] After implementing the above-mentioned storage test, the battery was discharged at a constant current rate of 0.2C at an ambient temperature of 25°C until the discharge end voltage was 2.0V, and then charged at a constant current constant voltage rate of 0.2C using the constant current constant voltage method until the charge upper limit voltage was 3.5V. The battery was discharged at a constant current rate of 5C at an ambient temperature of -30°C until the discharge end voltage was 2.0V, and the discharge capacity at this time (-30°C discharge capacity) was measured.

[0254] Note that each table shows the relative value of the capacity of each Example / Comparative Example, with the capacity of Comparative Example a0-1, which used the non-aqueous electrolyte Ra0-1 not containing (I-1) and (I-2), being set to 100. A larger value indicates a greater discharge capacity at low temperature after high-temperature storage, that is, a lower resistance after high-temperature storage.

[0255] <Evaluation of discharge capacity retention after overdischarge (LFP positive electrode / natural graphite negative electrode)>

[0256] Each battery cell subjected to the high-temperature (70°C) storage test as described above was subjected to a charge cycle of three times at an ambient temperature of 25°C, using a constant-current and constant-voltage charge cycle with a charge upper limit voltage of 3.5V and a 0.2C rate. The battery cell was then discharged at a 0.2C rate and a constant current until the discharge cutoff voltage reached 2.0V. The third discharge capacity was used as the capacity before the overdischarge test.

[0257] After the above-described operation, the discharged battery cell was further discharged at a constant resistance of 75Ω to 0V, thereby creating an overdischarge state, and then left at an ambient temperature of 25°C for 3 days. After this period, the battery cell was again charged at a constant current and constant voltage at a charge upper limit voltage of 3.5V and a 0.2C rate at an ambient temperature of 25°C. It was then discharged at a constant current rate of 0.2C to a discharge end voltage of 2.0V. The discharge capacity at this point (capacity after overdischarge test) was measured, and the capacity retention rate relative to the capacity before the overdischarge test (discharge capacity retention rate after overdischarge) was calculated using the following formula. It should be noted that the "discharge capacity retention rate after overdischarge" is the relative value of the capacity retention rate of each Example / Comparative Example, with the capacity retention rate of Comparative Example a0-1 being set to 100, as shown in each table.

[0258] Discharge capacity retention rate after over-discharge (%) = (capacity after over-discharge test / capacity before over-discharge test) × 100

[0259] In each table, "E1" indicates the discharge capacity at low temperature (-30°C discharge capacity) after high-temperature storage (relative value), and "E2" indicates the discharge capacity retention rate after overdischarge (relative value).

[0260] [Table 23]

[0261]

[0262] [Table 24]

[0263]

[0264] [Table 25]

[0265]

[0266] [Table 26]

[0267]

[0268] [Table 27]

[0269]

[0270] [Table 28]

[0271]

[0272] [Table 29]

[0273]

[0274] [Table 30]

[0275]

[0276] [Table 31]

[0277]

[0278] [Table 32]

[0279]

[0280] [Table 33]

[0281]

[0282] [Table 34]

[0283]

[0284] [Table 35]

[0285]

[0286] [Table 36]

[0287]

[0288] [Table 37]

[0289]

[0290] [Table 38]

[0291]

[0292] According to Tables 23 to 38, when compared under the same conditions of type and concentration of (I-1), it can be seen that the non-aqueous electrolytes of Examples can improve E1 and E2 in a well-balanced manner compared to the non-aqueous electrolytes of Comparative Examples.

[0293] Furthermore, examples with a non-aqueous electrolyte solution containing (I-2) of 10 to 15,000 ppm by mass showed further balanced improvements in E1 and E2. "Further balanced improvements in E1 and E2" refer to the fact that, for a non-aqueous electrolyte solution containing (I-2) of less than 10 ppm by mass, both "equivalent or better resistance after high-temperature storage" and "better discharge capacity retention after overdischarge after a high-temperature storage test" were achieved.

[0294] Next, in order to examine the influence of the content of cations other than lithium in the non-aqueous electrolyte when the non-aqueous electrolyte battery is a lithium ion battery, the contents shown in Tables 39 to 44 below were extracted from the above-mentioned Examples and Comparative Examples, and the content (mass ppm) of cations other than lithium in the non-aqueous electrolyte was determined by ICP emission spectroscopy.

[0295] [Table 39]

[0296]

[0297] [Table 40]

[0298]

[0299] [Table 41]

[0300]

[0301] [Table 42]

[0302]

[0303] [Table 43]

[0304]

[0305] [Table 44]

[0306]

[0307] It can be seen from Tables 39 to 44 that, when compared under the conditions of the same type and concentration of (I-1) and the same type of anion (I-2), the lower the content of cations other than lithium in the non-aqueous electrolyte, the more balanced the effect of improving the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after the high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after the high-temperature (70°C) storage test.

[0308] Industrial applicability

[0309] According to the present disclosure, a non-aqueous electrolyte solution and a non-aqueous electrolyte battery can be provided that can improve the low-temperature (-30°C) output characteristics (resistance after high-temperature storage) after a high-temperature (70°C) storage test and the discharge capacity retention rate after overdischarge after a high-temperature (70°C) storage test with good balance.

[0310] While the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the present disclosure.

[0311] This application is based on the Japanese patent application (Japanese Patent Application No. 2023-016466) filed on February 6, 2023, the contents of which are incorporated herein by reference.

Claims

1. A non-aqueous electrolyte comprising: (I-1) a compound represented by the following general formula [1a]; and (I-2) at least one member selected from the group consisting of a compound represented by the following general formula [1b] and a compound represented by the following general formula [1b′], The content of (I-2) in the non-aqueous electrolyte is 10 to 25000 ppm by mass, M + [X-S(=O)2-N-C(O)-R 1 ]-[1a] In the general formula [1a], X represents a halogen atom, R 1 represents a -CN group or an -OCN group, M + represents an alkali metal ion, In the general formula [1b], Y represents a boron atom, R 2 represents a fluorine atom, n is 0 to 4, m is 0 to 2, Q + represents an alkali metal ion, a tetraalkylammonium cation or a tetraalkylphosphonium cation, Q + [Z] - [1b’] In the general formula [1b'], [Z] - The anion portion shown is the structure of the following [1b-1] or a chloride anion, Q + represents an alkali metal ion, a tetraalkylammonium cation or a tetraalkylphosphonium cation, 2. The non-aqueous electrolyte according to claim 1, wherein The content of (I-2) in the non-aqueous electrolyte is 10 to 8000 ppm by mass.

3. The non-aqueous electrolyte according to claim 1 or 2, wherein The content of (I-1) in the non-aqueous electrolyte is 0.01 to 5.00% by mass.

4. The non-aqueous electrolyte according to claim 1 or 2, wherein X in the general formula [1a] is a fluorine atom.

5. The non-aqueous electrolyte according to claim 1 or 2, wherein The (I-2) is a salt compound comprising at least one counter anion selected from the group consisting of bis(oxalato)borate anions, tetrafluoroborate anions, chloride anions and perchlorate anions, and at least one counter cation selected from the group consisting of lithium cations, sodium cations, potassium cations, tetraalkylammonium cations and tetraalkylphosphonium cations.

6. The non-aqueous electrolyte according to claim 1 or 2, further comprising (II) a solute, wherein the solute is at least one member selected from the group consisting of LiPF6, LiSbF6, LiAsF6, LiCF3SO3, LiC4F9SO3, LiAlO2, LiAlCl4, and LiI, or at least one member selected from the group consisting of NaPF6, NaSbF6, NaAsF6, NaCF3SO3, NaC4F9SO3, NaAlO2, NaAlCl4, and NaI. 7 . The non-aqueous electrolyte according to claim 1 , further comprising (III) a non-aqueous organic solvent.

8. The non-aqueous electrolyte according to claim 7, wherein The (III) 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.

9. The non-aqueous electrolyte according to claim 8, wherein The (III) comprises a cyclic ester, and the cyclic ester is a cyclic carbonate.

10. The non-aqueous electrolyte according to claim 8, wherein The (III) comprises a chain ester, and the chain ester is a chain carbonate.

11. The non-aqueous electrolyte according to claim 1 or 2, further comprising at least one additive selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, dimethyl dicarbonate, ethynylethylene carbonate, trans-difluoroethylene carbonate, difluorobis(oxalato)phosphate, tetrafluorooxalatophosphate, (difluorophosphoryl)(fluorosulfonyl)imide salt, difluorophosphate, fluorosulfonate, nitrate, 1,3-propylene sultone, 1,3-propane sultone, 1,6-diisocyanatohexane, 1,3,2-dioxathiolane-2,2-dioxide, 4-propyl-1,3,2-dioxathiolane Alkane-2,2-dioxide, methylene methanedisulfonate, 1,2-ethanedisulfonic anhydride, methanesulfonic anhydride, methanesulfonyl fluoride, 1,4-dioxane-2,6-dione, tripropargyl phosphate, tris(trimethylsilyl)borate, (ethoxy)pentafluorocyclotriphosphazene, tetrafluoro(malonic acid)phosphate, tetrafluoro(picolinic acid)phosphate, 1,3-dimethyl-1,3-divinyl-1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)disiloxane, N,N'-carbonylbis(N-methylaminosulfonyl fluoride), tetravinylsilane, trivinylmethylsilane, tert-butylbenzene, tert-amylbenzene, fluorobenzene, and cyclohexylbenzene. 12 . A non-aqueous electrolyte battery comprising at least a positive electrode, a negative electrode, a separator, and the non-aqueous electrolyte according to claim 1 .

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