Battery additives, non-aqueous electrolytes containing them, and non-aqueous electrolyte secondary batteries

Abstract

To provide a non-aqueous electrolyte secondary battery having excellent cycle characteristics, and a non-aqueous electrolyte and an additive capable of achieving the same.SOLUTION: A battery additive includes at least one compound represented by the following general formula (1). (In the formula (1), RA1, RA2 and RA3 are each independently an unsubstituted or substituted hydrocarbon group having 1 to 11 carbon atoms, or represents an unsubstituted or substituted heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, and RA1 and RA2 may be linked to each other to form a ring.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an additive for batteries, a non-aqueous electrolyte containing the same, and a non-aqueous electrolyte secondary battery. [Background technology]

[0002] Non-aqueous electrolyte secondary batteries are increasingly being used in portable electronic devices such as smartphones, portable computers, and handheld video cameras, as well as in electric vehicles and hybrid vehicles that use electricity as part of their powertrain. In these applications, non-aqueous electrolyte secondary batteries are widely used as a power source.

[0003] Further improvements in the performance of non-aqueous electrolyte secondary batteries are required from the perspectives of usability time for portable electronic devices, driving range for automobiles, and safety. In particular, it is important that they can be used for long periods even after repeated charging and discharging, so various studies are being conducted to improve their cycle characteristics.

[0004] Examples of non-aqueous electrolytes with improved cycling properties include those described in Patent Document 1, Patent Document 2, and others. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2021-501978 [Patent Document 2] Patent No. 3730855 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, there has been a growing demand for non-aqueous electrolyte secondary batteries with improved cycle characteristics and high energy density. To achieve high energy density in non-aqueous electrolyte secondary batteries, it is necessary to operate them stably. However, there has been a problem in that operating non-aqueous electrolyte secondary batteries causes decomposition of the non-aqueous electrolyte, which reduces the cycle characteristics of the battery.

[0007] This invention has been made in view of the above-mentioned problems, and aims to provide a battery additive that enables the creation of a non-aqueous electrolyte secondary battery with excellent cycle characteristics. [Means for solving the problem]

[0008] In other words, the present invention is represented by the following [1] to [6].

[0009] [1] A battery additive comprising at least one compound represented by the following general formulas (1), (2), and (3).

[0010] [ka]

[0011] (In formula (1), R A1 , R A2 and R A3 Each independently represents an unsubstituted or substituted hydrocarbon group having 1 to 11 carbon atoms, or a heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, R A1 and R A2 These may be connected to each other to form a ring.

[0012] [ka]

[0013] (In formula (2), R B1represents a hydrocarbon group having 1 to 11 carbon atoms with or without substituents, or a heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms with or without substituents, and X B1 and X B2 each independently represent -CH2-, -O-, -NH- or -S-, but at least one of them is not -CH2-.)

[0014] [Chemical formula]

[0015] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0021] (In formula (2), R B1 This represents an unsubstituted or substituted hydrocarbon group having 1 to 11 carbon atoms, or an unsubstituted or substituted heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, and X B1 and X B2 Each of these independently represents -CH2-, -O-, -NH-, or -S-, but at least one of them is not -CH2-.

[0022] [ka]

[0023] (In formula (3), R C1 (This represents a cycloalkyl group with 3 to 9 carbon atoms.)

[0024] [4] The non-aqueous electrolyte according to [3], further containing an organic solvent.

[0025] [5] A non-aqueous electrolyte according to [3] or [4], further containing an electrolyte.

[0026] [6] A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte as described in any of [3] to [5]. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide a battery additive that enables the creation of a non-aqueous electrolyte secondary battery with excellent cycle characteristics. [Brief explanation of the drawing]

[0028] [Figure 1] This is a longitudinal cross-sectional view schematically showing an example of the structure of a coin-type battery of the non-aqueous electrolyte secondary battery of the present invention. [Figure 2] This is a schematic diagram showing the basic configuration of a cylindrical battery for the non-aqueous electrolyte secondary battery of the present invention. [Figure 3]This is a perspective view showing the internal structure of the cylindrical battery of the non-aqueous electrolyte secondary battery of the present invention in cross-section. [Figure 4] This is a schematic exploded perspective view showing the stacked electrode group inside the laminated battery of the non-aqueous electrolyte secondary battery of the present invention. [Figure 5] This is a schematic exploded perspective view showing a laminate-type battery of the non-aqueous electrolyte secondary battery of the present invention. [Figure 6] This is a schematic external view plan of a laminate-type battery of the non-aqueous electrolyte secondary battery of the present invention. [Modes for carrying out the invention]

[0029] The battery additive of the present invention, the non-aqueous electrolyte containing the same, and the non-aqueous electrolyte secondary battery will be described in detail below based on preferred embodiments.

[0030] In this specification, "average particle diameter (D50)" refers to the 50% particle diameter measured by laser diffraction scattering. In laser diffraction scattering, the particle diameter is the volume-based diameter, and the secondary particle diameter of the object being measured is measured. When measuring the average particle diameter by laser diffraction scattering, the object being measured is dispersed in a dispersion medium such as water or alcohol.

[0031] A. Battery additives First, the battery additive of the present invention will be described. The battery additive of the present invention contains at least one compound represented by the following general formulas (1), (2), and (3). Furthermore, the battery additive of the present invention may contain only one compound or two or more compounds.

[0032] [ka]

[0033] (In formula (1), R A1 , R A2 and R A3Each independently represents an unsubstituted or substituted hydrocarbon group having 1 to 11 carbon atoms, or a heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, R A1 and R A2 These may be connected to each other to form a ring.

[0034] [ka]

[0035] (In formula (2), R B1 This represents an unsubstituted or substituted hydrocarbon group having 1 to 11 carbon atoms, or an unsubstituted or substituted heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, and X B1 and X B2 Each of these independently represents -CH2-, -O-, -NH-, or -S-, but at least one of them is not -CH2-.

[0036] [ka]

[0037] (In formula (3), R C1 (This represents a cycloalkyl group with 3 to 9 carbon atoms.)

[0038] A1. Compounds represented by general formulas (1), (2), and (3) The compounds used in the present invention are represented by general formulas (1), (2), or (3).

[0039] In general formula (1), R A1 , R A2 and R A3 The hydrocarbon groups with 1 to 11 carbon atoms represented by ∫ represent groups that do not contain heterocycles. Examples of hydrocarbon groups with 1 to 11 carbon atoms include aliphatic hydrocarbon groups with 1 to 11 carbon atoms and aromatic hydrocarbon groups with 6 to 11 carbon atoms.

[0040] Examples of the above-mentioned aliphatic hydrocarbon groups having 1 to 11 carbon atoms include alkyl groups having 1 to 11 carbon atoms, and groups in which a portion of the methylene group in the alkyl group is substituted with a carbon-carbon unsaturated bond.

[0041] In this specification, the number of carbon atoms in a group with a predetermined number of carbon atoms refers to the number of carbon atoms in the group after a substituent has been substituted for a hydrogen atom in the group. For example, if a hydrogen atom in an aliphatic hydrocarbon group with 1 to 11 carbon atoms is substituted, the number of carbon atoms 1 to 11 refers to the number of carbon atoms in the group after the hydrogen atom has been substituted, and does not refer to the number of carbon atoms in the aliphatic hydrocarbon group before the hydrogen atom was substituted. Also, in this specification, if a methylene group in a group with a predetermined number of carbon atoms is substituted for a divalent group, the number of carbon atoms 1 to 11 refers to the number of carbon atoms in the group after the divalent group has been substituted, and does not refer to the number of carbon atoms in the group before the divalent group was substituted.

[0042] The alkyl groups having 1 to 11 carbon atoms mentioned above are linear alkyl groups or branched alkyl groups. Specific examples include, for example, methyl group, ethyl group, propyl group, iso-propyl group, butyl group, sec-butyl group, tert-butyl group, iso-butyl group, amyl group, iso-pentyl group, tert-pentyl group, hexyl group, 2-hexyl group, 3-hexyl group, heptyl group, 2-heptyl group, 3-heptyl group, iso-heptyl group, tert-heptyl group, 1-octyl group, iso-octyl group, tert-octyl group, undecyl group, dodecyl group, and the like.

[0043] The above alkyl groups have some of their hydrogen atoms replaced by halogen atoms, cyano groups, nitro groups, -SO2H, -OR groups. A4 ,-COOR A4 ,-CO-R A4 or -SR A4 It may be substituted with substituents such as R. A4 This represents a hydrogen atom, or an alkyl group having 1 to 3 carbon atoms, such as a methyl group, ethyl group, propyl group, or iso-propyl group.

[0044] The alkyl group in which part of the methylene group is replaced by a carbon-carbon unsaturated bond may have one unsaturated bond or two or more unsaturated bonds. Furthermore, the unsaturated bond may be a double bond or a triple bond.

[0045] Furthermore, when it is stated that a portion of the methylene group in an alkyl group is substituted with a carbon-carbon unsaturated bond, this includes groups that have an unsaturated bond at their terminus, where the methylene group constituting the terminal methyl group of the alkyl group is substituted with an unsaturated bond. For example, if the alkyl group before substitution with an unsaturated bond is an ethyl group (-CH2-CH3), and the methylene group constituting the terminal methyl group is substituted with an unsaturated bond (double bond), the group will be represented as -CH2-CH=CH2.

[0046] The above aromatic hydrocarbon groups having 6 to 11 carbon atoms represent aromatic groups, such as phenyl groups and groups in which some of the hydrogen atoms in the above-mentioned aliphatic hydrocarbon group are substituted with phenyl groups. One or more methylene groups of the above aliphatic hydrocarbon group may be substituted with divalent groups such as -O-, -S-, -O-CO-, and -CO-O-. In addition, one or more hydrogen atoms in the aromatic hydrocarbon group may be substituted with halogen atoms, cyano groups, nitro groups, -SO2H, and -OR groups. A4 ,-COOR A4 ,-CO-R A4 or -SR A4 It may be substituted with substituents such as R. A4 This represents a hydrogen atom, or an alkyl group having 1 to 3 carbon atoms, such as a methyl group, ethyl group, propyl group, or iso-propyl group. Specific examples of aromatic hydrocarbon groups having 6 to 11 carbon atoms include, for example, phenyl group, methylphenyl group, benzyl group, xylyl group, cumyl group, and mesityl group.

[0047] R in equation (1) above A1 , R A2 and R A3A heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms, represented by , can be a group in which some of the hydrogen atoms in the above-mentioned aliphatic hydrocarbon group having 1 to 11 carbon atoms are substituted with a heteroatom-containing group. Examples of the above heteroatom-containing group include groups containing oxygen, nitrogen, sulfur, phosphorus, or silicon atoms. Specific examples of the above heteroatom-containing group include, for example, a hydroxyl group, a carboxyl group, an oxyalkyl group, an epoxy group, an aldehyde group, a formyl group, a nitro group, a cyano group, and an amino group (-NR). 1 R 2 ), thiol group (-SR 3 Examples include silyl groups, sulfonate groups, and phosphate groups. 1 , R 2 and R 3 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of alkyl groups having 1 to 3 carbon atoms include methyl, ethyl, and propyl groups. Specific examples of such heteroatom-containing hydrocarbon groups include, for example, dimethylaminomethyl, diethylaminoethyl, methylthiomethyl, dimethylphosphinomethyl, trimethylsilylmethyl, and triethylsilylethyl groups.

[0048] A heteroatom-containing hydrocarbon group having 1 to 11 carbon atoms may have one or more methylene groups substituted with -O-, -S-, -O-CO-, or -CO-O-. Furthermore, one or more hydrogen atoms in the aliphatic hydrocarbon group constituting the heteroatom-containing hydrocarbon group may be replaced with halogen atoms, cyano groups, nitro groups, -SO2H, or -OR groups. A4 ,-COOR A4 ,-CO-R A4 or -SR A4 It may be substituted with substituents such as R. A4This represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, such as a methyl group, ethyl group, propyl group, or iso-propyl group. Specific examples of such heteroatom-containing hydrocarbon groups include, for example, methoxymethyl group, methoxyethyl group, methyl acetate group, ethyl acetate group, methyl propionate group, ethyl propionate group, methylthiomethyl group, methylthioethyl group, and 2-propanoatephenyl group.

[0049] The above R A1 and R A2 The ring formed by the connection of these two elements is R A1 and R A2 The ring structure should include a nitrogen atom in general formula (1) that is bonded to both of the above. From the viewpoint of achieving significant effects of the present invention, the above ring is preferably a 3-membered ring to a 10-membered ring, more preferably a 5-membered ring to a 9-membered ring, and most preferably a 5-membered ring or a 6-membered ring.

[0050] R A1 and R A2 The ring formed by the linkage of these elements may be a saturated ring or an unsaturated ring. Furthermore, one or more hydrogen atoms in the ring structure of the above ring may be substituted with halogen atoms such as alkyl groups having 1 to 4 carbon atoms, fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms.

[0051] R A1 and R A2Specific examples of rings formed by the linkage of these rings include, for example, pyrrolidine rings, methylpyrrolidine rings, pyrrole rings, pyrazolidine rings, imidazolidine rings, oxazolidine rings, isoxazolidine rings, thiazolidine rings, isothiazolidine rings, imidazole rings, pyrazole rings, oxazole rings, isoxazole rings, isothiazol rings, triazole rings, oxadiazole rings, thiadiazole rings, dioxazole rings, dithiazole rings, tetrazole rings, oxatetrazole rings, thiatetrazole rings, pentazole rings, piperidine rings, piperazine rings, morpholine rings, thiomorpholine rings, hexahydro-1,3,5-triazine rings, diazine rings, oxazine rings, thiadin rings, triazine rings, tetrazole rings, and pentazole rings.

[0052] From the viewpoint of achieving remarkable effects of the present invention, R in general formula (1) A1 and R A2 It is preferable that the two are connected to form a ring. From the viewpoint of making the effects of the present invention more pronounced, R A1 and R A2 The number of carbon atoms in the ring formed by the two is preferably 3 to 11, more preferably 3 to 8, and most preferably 3 to 7.

[0053] From the viewpoint of making the effects of the present invention more pronounced, R A1 and R A2 The number of heteroatoms in the ring formed by is preferably one or more, more preferably one to five, even more preferably two to four, and most preferably two. A1 and R A2 The number of heteroatoms in the ring formed by and is R in general formula (1) A1 and R A2 It contains one nitrogen atom to which both are bonded.

[0054] R A1 and R A2The ring formed by these two components may be aromatic or non-aromatic, but from the viewpoint of achieving the remarkable effects of the present invention, a non-aromatic ring is preferred.

[0055] From the viewpoint of making the effects of the present invention more pronounced, R A1 and R A2 Among the rings formed by the two, morpholine rings, thiamorpholine rings, and imidazole rings are preferred, with morpholine rings and imidazole rings being more preferred.

[0056] From the viewpoint of making the effects of the present invention more pronounced, R A3 However, it is preferably a hydrocarbon group having 1 to 11 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 11 carbon atoms, even more preferably an aliphatic hydrocarbon group having 1 to 8 carbon atoms, even more preferably an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and most preferably an aliphatic hydrocarbon group having 1 to 3 carbon atoms.

[0057] R A3 However, in the case of an aromatic hydrocarbon group having 6 to 11 carbon atoms, from the viewpoint that the effects of the present invention are particularly pronounced, it is preferable that the aromatic hydrocarbon group has 6 to 10 carbon atoms, more preferably that it has 6 to 9 carbon atoms, even more preferably that it has 6 to 7 carbon atoms, and most preferably that it is a phenyl group or a methylphenyl group.

[0058] Compounds represented by general formula (1) can be produced using well-known methods without being particularly limited by their production method. For example, 4-(methylsulfonyl)morpholine can be efficiently produced by reacting morpholine with methanesulfonyl chloride in the presence of an organic base.

[0059] Specific examples of compounds represented by general formula (1) include the following compounds 1-1 to 1-6, but the present invention is not limited to these compounds.

[0060] [ka]

[0061] From the viewpoint of achieving significant effects of the present invention, it is preferable that the battery additive of the present invention contains at least one of compound 1-1 and compound 1-2.

[0062] In general formula (2), R B1 Examples of hydrocarbon groups having 1 to 11 carbon atoms represented by this formula include those similar to the hydrocarbon groups having 1 to 11 carbon atoms exemplified in general formula (1).

[0063] In general formula (2), R B1 Examples of heteroatom-containing hydrocarbon groups having 1 to 11 carbon atoms, as represented by the formula (1), include those similar to the heteroatom-containing hydrocarbon groups having 1 to 11 carbon atoms exemplified in general formula (1).

[0064] X in general formula (2) B1 and X B2 Each of these is independently selected from the group -CH2-, -O-, -NH-, or -S-.

[0065] From the viewpoint of making the effects of the present invention more pronounced, R B1 It is preferably an aliphatic hydrocarbon group having 1 to 11 carbon atoms, or an aliphatic hydrocarbon group having 1 to 11 carbon atoms in which one or more methylene groups are substituted with ester groups, and more preferably an aliphatic hydrocarbon group having 1 to 11 carbon atoms in which one or more methylene groups are substituted with ester groups.

[0066] From the viewpoint of making the effects of the present invention more pronounced, R B1 The number of carbon atoms in the hydrocarbon group represented is preferably 3 to 11, more preferably 3 to 8, and even more preferably 4 to 8.

[0067] From the viewpoint of achieving remarkable effects of the present invention, X in general formula (2) B1is -O-, -NH- or -S-, and X B2 is preferably -CH2-, and X B1 is -O- or -S-, and X B2 is more preferably -CH2-, and X B1 is -S-, and X B2 is even more preferably -CH2-.

[0068] The compound represented by the general formula (2) is not particularly limited by its production method and can be produced using well-known production methods. For example, ethyl-α-methyl-2,4-dioxo-3-thiazolidine acetate can be efficiently produced by reacting thiazolidinedione with ethyl-2-bromopropionate in the presence of a base such as potassium hydroxide.

[0069] Specific examples of the compound represented by the general formula (2) include the following compounds 2-1 to 2-5, etc., but the present invention is not limited to these compounds.

[0070]

Chemical formula

[0071] From the viewpoint that the effect of the present invention becomes remarkable, the additive for a battery of the present invention preferably contains at least one of Compound 2-1 and Compound 2-2.

[0072] In the general formula (3), R C1 Examples of the cycloalkyl group having 3 to 9 carbon atoms represented by include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 2,4-dimethylcyclohexyl group, etc. A part of the hydrogen atoms in the cycloalkyl group may be substituted with an alkyl group having 1 to 4 carbon atoms. From the viewpoint that the effect of the present invention becomes remarkable, R C1The cycloalkyl group represented is preferably a 3-membered to 6-membered ring cycloalkyl group, and more preferably a 5-membered to 6-membered ring cycloalkyl group. From the viewpoint of achieving remarkable effects of the present invention, R C1 The number of carbon atoms in the cycloalkyl group represented by is preferably 5 to 8, and more preferably 5 to 7.

[0073] Compounds represented by general formula (3) can be produced using well-known methods without being particularly limited by their production method. For example, cyclohexyl cyanoacetate can be efficiently produced by reacting cyanoacetic acid with cyclohexanol in the presence of an acid catalyst.

[0074] Specific examples of compounds represented by general formula (3) include compounds 3-1 to 3-3 listed below, but the present invention is not limited to these compounds.

[0075] [ka]

[0076] From the viewpoint of achieving significant effects of the present invention, it is preferable that the battery additive of the present invention contains at least one of compound 3-1 and compound 3-2.

[0077] From the viewpoint of achieving remarkable effects of the present invention, the battery additive of the present invention preferably contains at least one compound represented by general formula (1) and one compound represented by general formula (2), and more preferably contains the compound represented by general formula (1).

[0078] The content of the compounds represented by general formulas (1), (2), and (3) may be 100 parts by mass per 100 parts by mass of the battery additive (i.e., the battery additive of the present invention may contain only the compounds represented by general formulas (1), (2), and (3)). The battery additive of the present invention may also contain components other than the compounds represented by general formulas (1), (2), and (3).

[0079] A2. Other The battery additive of the present invention contains compounds represented by general formulas (1), (2), and (3), but may also contain other components as needed.

[0080] The battery additive of the present invention can be used as an additive to the non-aqueous electrolyte in known non-aqueous electrolyte secondary batteries such as lithium-ion non-aqueous electrolyte secondary batteries, sodium-ion non-aqueous electrolyte secondary batteries, potassium-ion non-aqueous electrolyte secondary batteries, calcium non-aqueous electrolyte secondary batteries, and magnesium-ion non-aqueous electrolyte secondary batteries. In addition to being used as an additive to the non-aqueous electrolyte, the battery additive of the present invention can also be used as an electrode material.

[0081] B. Non-aqueous electrolyte Next, the non-aqueous electrolyte of the present invention will be described. The non-aqueous electrolyte of the present invention comprises at least one compound represented by general formulas (1), (2), and (3).

[0082] The components constituting the non-aqueous electrolyte of the present invention will be described below.

[0083] B1. Compounds represented by general formulas (1), (2), and (3) The non-aqueous electrolyte of the present invention contains compounds represented by the general formulas (1), (2), and (3) described above.

[0084] From the viewpoint of achieving remarkable effects of the present invention, the total content of the compounds represented by general formulas (1), (2), and (3) in the non-aqueous electrolyte of the present invention is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the non-aqueous electrolyte. Furthermore, from the viewpoint of achieving remarkable effects of the present invention, the total content of the compounds represented by general formulas (1), (2), and (3) in the non-aqueous electrolyte of the present invention is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the non-aqueous electrolyte.

[0085] B2. Organic Solvents From the viewpoint of enhancing the effects of the present invention, the non-aqueous electrolyte of the present invention preferably further contains an organic solvent in addition to at least one compound represented by general formulas (1), (2), and (3). The organic solvent that can be used in the non-aqueous electrolyte of the present invention is not particularly limited as long as it is a known organic solvent used in non-aqueous electrolytes of non-aqueous electrolyte secondary batteries. Specific examples of organic solvents include saturated linear carbonate compounds, saturated cyclic carbonate compounds, saturated linear ester compounds, saturated cyclic ester compounds, linear ether compounds, cyclic ether compounds, sulfoxide compounds, sulfone compounds, amide compounds, and the like. Ionic liquids can also be used as the organic solvent. The organic solvent may be used alone or in combination of two or more types.

[0086] Examples of the saturated chain carbonate compounds mentioned above include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl butyl carbonate, methyl-tert-butyl carbonate, diisopropyl carbonate, and tert-butylpropyl carbonate. Among these, dimethyl carbonate and ethyl methyl carbonate are preferred from the viewpoint of exhibiting the effects of the present invention.

[0087] Examples of the saturated cyclic carbonate compounds mentioned above include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, and 1,1-dimethylethylene carbonate. Among these, ethylene carbonate, 1,2-propylene carbonate, and 1,3-propylene carbonate are preferred from the viewpoint of exhibiting the effects of the present invention.

[0088] Examples of the saturated chain ester compounds mentioned above include monoester compounds and diester compounds having a total of 2 to 8 carbon atoms in the molecule. Specific examples of saturated chain ester compounds include methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, methyl malonate, ethyl malonate, methyl succinate, ethyl succinate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, propylene glycol diacetyl, and the like. Among these, monoester compounds are preferred from the viewpoint of demonstrating the effects of the present invention, and methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, and ethyl propionate are more preferred.

[0089] Examples of the saturated cyclic ester compounds mentioned above include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, and δ-octanolactone. Among these, γ-butyrolactone is preferred from the viewpoint of exhibiting the effects of the present invention.

[0090] Examples of the above-mentioned chain-like ether compounds and cyclic ether compounds include dimethoxyethane, ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis(methoxycarbonyloxy)ethane, 1,2-bis(ethoxycarbonyloxy)ethane, 1,2-bis(ethoxycarbonyloxy)propane, ethylene glycol bis(trifluoroethyl) ether, propylene glycol bis(trifluoroethyl) ether, ethylene glycol bis(trifluoromethyl) ether, and diethylene glycol bis(trifluoroethyl) ether. Among these, dioxolane is preferred from the viewpoint of exhibiting the effects of the present invention.

[0091] Examples of the above-mentioned sulfoxide compounds include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, diphenyl sulfoxide, and thiophene. Among these, dimethyl sulfoxide is preferred from the viewpoint of demonstrating the effects of the present invention.

[0092] Examples of the above-mentioned sulfone compounds include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, diphenyl sulfone, sulfolane (also called tetramethylene sulfone), 3-methylsulfolane, 3,4-dimethylsulfolane, 3,4-diphenylmethylsulfolane, sulfolene, 3-methylsulfolene, 3-ethylsulfolene, and 3-bromomethylsulfolene. Among these, sulfolane and tetramethylsulfolane are preferred from the viewpoint of exhibiting the remarkable effects of the present invention.

[0093] Examples of the above-mentioned amide compounds include N-methylpyrrolidone, dimethylformamide, and dimethylacetamide. Among these, N-methylpyrrolidone and dimethylformamide are preferred from the viewpoint of exhibiting the remarkable effects of the present invention.

[0094] The non-aqueous electrolyte of the present invention can use other organic solvents such as acetonitrile, propionitrile, nitromethane or their derivatives, or various ionic liquids.

[0095] The non-aqueous electrolyte of the present invention preferably contains at least one organic solvent selected from the group consisting of saturated linear carbonate compounds, linear ether compounds, cyclic ether compounds, and saturated linear ester compounds, and more preferably contains at least one organic solvent selected from the group consisting of saturated linear carbonate compounds and saturated cyclic carbonate compounds. By containing these organic solvents, the viscosity of the non-aqueous electrolyte of the present invention can be lowered, the mobility of electrolyte ions can be increased, and other battery characteristics such as power density can be improved. Furthermore, by lowering the viscosity of the non-aqueous electrolyte of the present invention, the battery characteristics of the non-aqueous electrolyte secondary battery at low temperatures can be improved.

[0096] The organic solvent content in the non-aqueous electrolyte of the present invention is preferably 90 parts by mass or more, more preferably 92 parts by mass or more, and even more preferably 95 parts by mass or more, per 100 parts by mass of the non-aqueous electrolyte. Furthermore, the organic solvent content in the non-aqueous electrolyte of the present invention is preferably 99.99 parts by mass or less, more preferably 99.95 parts by mass or less, and even more preferably 99.9 parts by mass or less, per 100 parts by mass of the non-aqueous electrolyte. By setting the organic solvent content within the above range, the effects of the present invention become more pronounced.

[0097] B3. Polymer compounds The non-aqueous electrolyte of the present invention may further contain a polymer compound. Examples of polymer compounds include those used in a gelled state (polymer gel) in the organic solvent mentioned above, and those used as a dispersion medium for dispersing electrolytes, as described later.

[0098] Examples of polymer compounds that can be used as the polymer gel mentioned above include those that do not contain the aforementioned organic solvents, such as polyethylene oxide, polypropylene oxide, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polyethylene, polyvinylidene fluoride, and polyhexafluoropropylene.

[0099] Examples of polymer compounds used as dispersion media include polyethylene oxide, polypropylene oxide, and polystyrene sulfonic acid.

[0100] There are no particular restrictions on the blending ratio and blending method of the polymer compound used as a polymer gel and the polymer compound used as a dispersion medium; known blending ratios and known compounding methods in this art can be adopted.

[0101] In the non-aqueous electrolyte of the present invention, the content of the polymer compound used as a polymer gel is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, relative to the total amount of the organic solvent and the polymer compound. Furthermore, the content of the polymer compound used as a polymer gel is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, relative to the total amount of the organic solvent and the polymer compound. By setting the content of the polymer compound used as a polymer gel within the above range, the effects of the present invention are more easily obtained.

[0102] In the non-aqueous electrolyte of the present invention, the content of the polymer compound used as a dispersion medium is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the non-aqueous electrolyte. The content of the polymer compound used as a dispersion medium is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the non-aqueous electrolyte. By setting the content of the polymer compound used as a dispersion medium within the above range, the effects of the present invention are more easily obtained.

[0103] B4. Electrolytes The non-aqueous electrolyte of the present invention may further contain an electrolyte. The electrolyte used in the non-aqueous electrolyte of the present invention is not particularly limited as long as it is a known electrolyte used in non-aqueous electrolytes for non-aqueous secondary batteries. Examples of electrolytes include lithium salts, sodium salts, potassium salts, calcium salts, magnesium salts, and the like.

[0104] Specific examples of the above lithium salts include, for example, LiPF6, LiBF4, LiAsF6, LiCF3SO3, LiCF3CO2, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(SO2F)2, LiC(CF3SO2)3, LiB(CF3SO3)4, LiB(C2O4)2, LiBF2(C2O4), LiSbF6, LiSiF5, LiSCN, LiClO4, LiCl, LiF, LiBr, LiI, LiAlF4, LiAlCl4, LiPO2F2, and their derivatives.

[0105] Specific examples of the sodium salts mentioned above include, for example, NaPF6, NaBF4, NaAsF6, NaCF3SO3, NaCF3CO2, NaN(CF3SO2)2, NaN(C2F5SO2)2, NaN(SO2F)2, NaC(CF3SO2)3, NaB(CF3SO3)4, NaB(C2O4)2, NaBF2(C2O4), NaSbF6, NaSiF5, NaSCN, NaClO4, NaCl, NaF, NaBr, NaI, NaAlF4, NaAlCl4, NaPO2F2, and their derivatives.

[0106] Specific examples of the potassium salts mentioned above include, for example, KPF6, KBF4, KAsF6, KCF3SO3, KCF3CO2, KN(CF3SO2)2, KN(C2F5SO2)2, KN(SO2F)2, KC(CF3SO2)3, KB(CF3SO3)4, KB(C2O4)2, KBF2(C2O4), KSbF6, KSiF5, KSCN, KClO4, KCl, KF, KBr, KI, KAlF4, KAlCl4, KPO2F2, and their derivatives.

[0107] Specific examples of the calcium salts mentioned above include, for example, Ca(PF6)2, Ca(BF4)2, Ca[FSI]2, Ca[TFSI]2, Ca[f3C]2, Ca[BOB]2, Ca(ClO4)2, Ca[BF3(CF3)]2, Ca[BF3(C2F5)]2, Ca[BF3(C3F7)]2, Ca[BF3(C4F9)]2, Ca[C(SO2CF3)3]2, Ca(CF3SO2O)2, Ca(CF3COO)2, and Ca(RCOO)2 (where R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group), and their derivatives.

[0108] Specific examples of the above magnesium salts include, for example, Mg(PF6)2, Mg(BF4)2, Mg[FSI]2, Mg[TFSI]2, Mg[f3C]2, Mg[BOB]2, Na(ClO4)2, Mg[BF3(CF3)]2, Mg[BF3(C2F5)]2, Mg[BF3(C3F7)]2, Mg[BF3(C4F9)]2, Mg[C(SO2CF3)3]2, Mg(CF3SO3)2, Mg(CF3COO)2, and Mg(RCOO)2 (where R is an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group), and their derivatives.

[0109] From the viewpoint of achieving the effects of the present invention, the non-aqueous electrolyte of the present invention preferably contains a thium salt or a sodium salt as the electrolyte, and more preferably contains a lithium salt.

[0110] From the viewpoint of achieving remarkable effects of the present invention, it is preferable to use at least one lithium salt selected from the group consisting of LiPF6, LiBF4, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(SO2F)2, LiPO2F2, LiC(CF3SO2)3, derivatives of LiCF3SO3, and derivatives of LiC(CF3SO2)3 as the lithium salt used in the liquid non-aqueous electrolyte or polymer gel-like non-aqueous electrolyte.

[0111] From the viewpoint of achieving significant effects of the present invention, it is preferable to use at least one lithium salt selected from the group consisting of LiPF6, LiBF4, LiClO4, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(SO2F)2, LiC(CF3SO2)3, LiB(CF3SO3)4, and LiB(C2O4)2 as the lithium salt used in the polymer electrolyte (or a polymer electrolyte obtained by dispersing a lithium salt without using a solvent).

[0112] The electrolyte content in the non-aqueous electrolyte of the present invention is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.05 parts by mass or more, per 100 parts by mass of the non-aqueous electrolyte. Furthermore, the electrolyte content in the non-aqueous electrolyte is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the non-aqueous electrolyte. By setting the electrolyte content within the above range, a sufficient current density can be obtained and the stability of the non-aqueous electrolyte can be improved.

[0113] B5. Electrolyte Additives The non-aqueous electrolyte of the present invention may contain, in addition to at least one compound represented by general formulas (1), (2), and (3), the organic solvent, polymer compound, and electrolyte described above, known electrolyte additives to the extent that they do not impair the effects of the present invention. Examples of electrolyte additives include electrode film-forming agents, antioxidants, flame retardants, and overcharge inhibitors.

[0114] The electrode film-forming agents described above include those that form a solid electrolyte interface (SEI) film on the electrode surface and improve ion conductivity in the electrolyte. The non-aqueous electrolyte of the present invention may contain known electrode film-forming agents. Specific examples of electrode film-forming agents include, for example, fluorine-containing carbonate, vinylene carbonate, propanesultone, a compound having a nitrile group as described in Japanese Patent No. 4918740, and an aminosulfonyliimide salt as described in Japanese Patent Application Publication No. 2017-122058.

[0115] The above-mentioned antioxidants include those that improve the storage stability of the binder and non-aqueous electrolyte contained in the electrode. The non-aqueous electrolyte of the present invention may contain known antioxidants. Specific examples of antioxidants include, for example, the water-soluble antioxidant described in Japanese Patent No. 6828685, the phenolic antioxidant, phosphorus-based antioxidant and sulfur-based antioxidant described in Japanese Patent No. 6762465, and the antioxidant described in Japanese Patent No. 4411735.

[0116] The above-mentioned flame retardants include those that impart flame retardancy to non-aqueous electrolytes and those that suppress lithium dendrite formation. The non-aqueous electrolyte of the present invention may include known flame retardants. Specific examples of flame retardants include, for example, those described in Japanese Patent Publication No. 10-172615 and Japanese Patent Publication No. 2016-045987.

[0117] The above-mentioned overcharge inhibitors are used to prevent heat generation and leakage of the non-aqueous electrolyte during overcharging of non-aqueous electrolyte secondary batteries. The non-aqueous electrolyte of the present invention may include known overcharge inhibitors. Specific examples of overcharge inhibitors include those described in Japanese Patent Application Publication No. 2020-047426 and Japanese Patent Application Publication No. 2017-91687, among others.

[0118] The total content of electrolyte additives in the non-aqueous electrolyte of the present invention is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the non-aqueous electrolyte. Furthermore, the total content of electrolyte additives in the non-aqueous electrolyte of the present invention is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the non-aqueous electrolyte. By setting the total content of electrolyte additives within the above range, it becomes easier to obtain an effect commensurate with the amount added.

[0119] C. Non-aqueous electrolyte secondary battery Next, the non-aqueous electrolyte secondary battery of the present invention (hereinafter sometimes referred to as "the battery of the present invention") will be described. The battery of the present invention includes a positive electrode, a negative electrode, and the non-aqueous electrolyte described above. The configuration of the battery of the present invention will be described in detail below.

[0120] C1. Positive electrode The positive electrode that can be used in the battery of the present invention is not particularly limited as long as it is a known positive electrode used in non-aqueous electrolyte secondary batteries. Specific examples of positive electrodes include electrodes using an electrode mixture layer containing a positive electrode active material, and electrodes made of metal foil. The electrode mixture layer may contain a binder and a conductive additive in addition to the positive electrode active material. An electrode using an electrode mixture layer may consist only of the electrode mixture layer, or it may be a multilayer structure including a current collector, a conductive layer, a coating layer, etc. Methods for forming the electrode mixture layer include, for example, a method of applying a positive electrode mixture slurry obtained by slurrying a positive electrode active material, a binder, and a conductive additive with an organic solvent or water, and then drying it. In the battery of the present invention, from the viewpoint of easily obtaining a battery with a large electromotive force, it is preferable that the positive electrode is an electrode using an electrode mixture layer.

[0121] C1-1. Positive electrode active material The positive electrode active material can be any known positive electrode active material used in non-aqueous electrolyte secondary batteries. Specific examples of positive electrode active materials include lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, lithium-containing silicate compounds, lithium-containing transition metal sulfate compounds, and the like.

[0122] From the perspective of achieving good battery characteristics in the battery of the present invention, the transition metal in the above lithium-containing transition metal composite oxide is preferably vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, or the like. Specific examples of the lithium-containing transition metal composite oxide include, for example, lithium cobalt composite oxides such as LiCoO2, lithium nickel composite oxides such as LiNiO2, lithium manganese composite oxides such as LiMnO2, LiMn2O4, and Li2MnO3, and compounds in which a part of the transition metal atoms constituting the main body of these lithium transition metal composite oxides is substituted with other metals (for example, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, etc.).

[0123] Examples of the lithium transition metal composite oxide in which a part of the main transition metal atoms is substituted with other metals include, for example, Li 1.1 Mn 1.8 Mg 0.1 O4, Li 1.1 Mn 1.85 Al 0.05 O4, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Mn 0.5 O2, LiNi 0.80 Co 0.17 Al 0.03 O2, LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiMn 1.8 Al 0.2 O4, LiNi 0.5 Mn 1.5 O4, Li2MnO3-LiMO2 (M = Co, Ni, Mn), etc.

[0124] From the viewpoint of obtaining good battery characteristics for the battery of the present invention, the transition metal of the lithium-containing transition metal phosphate compound described above is preferably vanadium, titanium, manganese, iron, cobalt, nickel, etc. Specific examples of lithium-containing transition metal phosphate compounds include, for example, LiFePO4, LiM x Fe 1-x Examples include lithium-containing iron phosphate compounds such as PO4 (M=Co, Ni, Mn; 0≦x<1), lithium-containing cobalt phosphate compounds such as LiCoPO4, and those in which some of the transition metal atoms that make up these lithium-containing transition metal phosphate compounds are replaced with other metals such as aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, and niobium, as well as lithium-containing vanadium phosphate compounds such as Li3V2(PO4)3.

[0125] Examples of the lithium-containing silicate compounds mentioned above include Li2FeSiO4.

[0126] Examples of the lithium-containing transition metal sulfate compounds mentioned above include LiFeSO4 and LiFeSO4F.

[0127] The battery of the present invention can use a sulfur-modified organic compound as the positive electrode active material. Examples of the sulfur-modified organic compound include those in which sulfur atoms are physically adsorbed onto the organic compound, or in which sulfur atoms form covalent bonds with atoms constituting the organic compound. Among these, those in which some of the sulfur atoms form covalent bonds with the organic compound are preferred. Specific examples of the above organic compounds include, for example, polyacrylonitrile compounds, elastomer compounds, polyether compounds, pitch compounds, polynuclear aromatic ring compounds, aliphatic hydrocarbon oxides, polyacene compounds, polyamide compounds, hexachlorobutadiene, and the like.

[0128] The method for producing sulfur-modified organic compounds is not particularly limited as long as it is a known production method. For example, sulfur-modified organic compounds can be produced by mixing sulfur and an organic compound and heating them at 250°C to 600°C under a non-oxidizing atmosphere. The organic compound used as a raw material may be a single type or a combination of two or more types. A non-oxidizing atmosphere refers to an atmosphere with an oxygen concentration of less than 5% by volume, preferably an atmosphere with an oxygen concentration of less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0129] Specific examples of the above-mentioned sulfur-modified organic compounds include, for example, sulfur-modified polyacrylonitrile compounds, sulfur-modified elastomer compounds, sulfur-modified polyether compounds, sulfur-modified pitch compounds, sulfur-modified polynuclear aromatic ring compounds, sulfur-modified aliphatic hydrocarbon oxides, polythienoacene compounds, sulfur-modified polyamide compounds, and polysulfide carbons. In the present invention, sulfur-modified polyacrylonitrile compounds are preferred from the viewpoint of easily obtaining electrodes with large charge-discharge capacity. From the viewpoint of obtaining even greater charge-discharge capacity, the sulfur content in the sulfur-modified organic compound is preferably 25% to 70% by mass. The sulfur content in the sulfur-modified organic compound can be measured, for example, by elemental analysis using a CHN analyzer capable of analyzing sulfur and oxygen (e.g., Elementor's Virio Microcube).

[0130] The polyacrylonitrile compound, as the organic compound constituting the sulfur-modified polyacrylonitrile compound, may be a homopolymer of acrylonitrile or a copolymer of acrylonitrile and other monomers. If the acrylonitrile content in the polyacrylonitrile compound is too low, the battery performance will be low. If the acrylonitrile content is sufficient, carbonization is relatively easy, and the carbide of the polyacrylonitrile compound exhibits relatively high conductivity. In the copolymer of acrylonitrile and other monomers, the acrylonitrile content is preferably at least 90% by mass, more preferably 95% by mass or more, and even more preferably a homopolymer of polyacrylonitrile. By setting the acrylonitrile content within the above range, it is possible to increase the capacity of non-aqueous electrolyte secondary batteries.

[0131] Examples of other monomers in the copolymer of acrylonitrile and other monomers mentioned above include acrylic acid, vinyl acetate, N-vinylformamide, and N,N'-methylenebis(acrylamide). The sulfur content in the sulfur-modified polyacrylonitrile compound is preferably 25% to 80% by mass, and more preferably 25% to 70% by mass, from the viewpoint of obtaining a large charge-discharge capacity. As a method for producing the sulfur-modified polyacrylonitrile compound, a method of heat-treating sulfur and polyacrylonitrile can be used. Such heat treatment is preferably carried out in a temperature range of 250°C to 600°C.

[0132] Examples of rubbers used as organic compounds constituting the above-mentioned sulfur-modified elastomer compound include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, and acrylonitrile-butadiene rubber. These rubbers can be used individually or in combination of two or more. The rubber may be vulcanized rubber or unvulcanized rubber. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the sulfur-modified elastomer compound is preferably 35% to 75% by mass, and more preferably 40% to 70% by mass. As a method for producing the sulfur-modified elastomer compound, a method of heat-treating sulfur and rubber can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 250°C to 550°C. The above-mentioned non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0133] Examples of polyether compounds that constitute the above-mentioned sulfur-modified polyether compounds include polyethylene glycol, polypropylene glycol, ethylene oxide / propylene oxide copolymer, and polytetramethylene glycol. The polyether compounds may have alkyl ether groups, alkylphenyl ether groups, or acyl groups at their termini, and may also be ethylene oxide adducts of polyols such as glycerin and sorbitol. The weight-average molecular weight of the polyether compound is usually 100 to 20,000, preferably 150 to 10,000, and more preferably 200 to 8,000. Setting the weight-average molecular weight of the polyether compound within the above range makes it easier to handle. In this specification, the weight-average molecular weight is the value on a polystyrene basis obtained by gel permeation chromatography (GPC).

[0134] Unreacted elemental sulfur can degrade the cycle characteristics of secondary batteries, so it is preferable to remove it from the sulfur-modified polyether compound by means of heating or solvent washing, for example. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content of the sulfur-modified polyether compound is preferably 30% to 75% by mass, and more preferably 40% to 70% by mass.

[0135] Examples of pitches as organic compounds constituting the above-mentioned sulfur-modified pitch compounds include petroleum pitch, coal pitch, mesophase pitch, asphalt, coal tar, coal tar pitch, organically synthesized pitch obtained by polycondensation of condensed polycyclic aromatic hydrocarbon compounds, and organically synthesized pitch obtained by polycondensation of heteroatom-containing condensed polycyclic aromatic hydrocarbon compounds. Pitches are mixtures of various compounds and include condensed polycyclic aromatics. The condensed polycyclic aromatics contained in pitches may be a single type or multiple types. These condensed polycyclic aromatics may contain nitrogen atoms or sulfur atoms in addition to carbon and hydrogen atoms in the ring. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the sulfur-modified pitch compound is preferably 20% to 75% by mass, and more preferably 25% to 70% by mass. As a method for producing the sulfur-modified pitch compound, a method of heat-treating sulfur and pitches can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 300°C to 500°C. The above-mentioned non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0136] Examples of polycyclic aromatic ring compounds that constitute the above-mentioned sulfur-modified polynuclear aromatic ring compounds include benzene-based aromatic ring compounds such as naphthalene, anthracene, tetracene, pentacene, phenanthrene, chrysene, picene, pyrene, benzopyrene, perylene, and coronene; aromatic ring compounds in which a portion of the benzene-based aromatic ring compound is a five-membered ring; or heteroatom-containing heteroaromatic ring compounds in which some of these carbon atoms are replaced by sulfur, oxygen, nitrogen, etc. Furthermore, these polynuclear aromatic ring compounds may have substituents such as chain-like or branched alkyl groups, alkoxyl groups, hydroxyl groups, carboxyl groups, amino groups, aminocarbonyl groups, aminothio groups, mercaptothiocarbonylamino groups, and carboxyalkylcarbonyl groups having 1 to 12 carbon atoms. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the sulfur-modified polynuclear aromatic ring compound is preferably 35% to 75% by mass, and more preferably 40% to 70% by mass. As a method for producing sulfur-modified polynuclear aromatic ring compounds, a method of heat treatment of sulfur and pitch can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 250°C to 550°C. The above non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0137] Examples of aliphatic hydrocarbon oxides as organic compounds constituting the above-mentioned sulfur-modified aliphatic hydrocarbon oxides include aliphatic alcohols, aliphatic aldehydes, aliphatic ketones, aliphatic epoxides, fatty acids, and other aliphatic hydrocarbon oxides. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the sulfur-modified aliphatic hydrocarbon oxide is preferably 40% to 80% by mass, and more preferably 45% to 75% by mass. As a method for producing the sulfur-modified aliphatic hydrocarbon oxide, a method of heat-treating sulfur and aliphatic hydrocarbon oxide can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 300°C to 500°C. The above-mentioned non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0138] The above-mentioned polythienoacene compound is a compound having a sulfur-containing polythienoacene structure, represented by the following general formula (4).

[0139] [ka]

[0140] Examples of organic compounds constituting the above-mentioned polythienoacene compound include aliphatic polymer compounds having a linear structure such as polyethylene, and polymer compounds having a thiophene structure such as polythiophene. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the polythienoacene compound is preferably 25% to 85% by mass, and more preferably 30% to 80% by mass. As a method for producing the polythienoacene compound, a method of heat-treating sulfur with an aliphatic polymer compound or a polymer compound having a thiophene structure can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 300°C to 600°C. The above-mentioned non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0141] The organic compounds constituting the above-mentioned sulfur-modified polyamide compounds are organic compounds having a carbon skeleton derived from a polymer having an amide bond, and specifically, examples include aminocarboxylic acid compounds, and compounds obtained by reacting a polyamine compound with a polycarboxylic acid compound. The sulfur content in the sulfur-modified polyamide compound is preferably 35% to 75% by mass, and more preferably 40% to 70% by mass, from the viewpoint of obtaining a large charge-discharge capacity. As a method for producing the sulfur-modified polyamide compound, a method of heat-treating sulfur and an organic compound having a carbon skeleton derived from a polymer having an amide bond can be used. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 250°C to 600°C. The above-mentioned non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0142] The above polysulfide carbon has the general formula (CS x ) nThe compound is represented by (x is between 0.5 and 2, and n is a number greater than or equal to 4). Examples of organic compounds constituting polysulfide carbon include those obtained by reacting a complex of an alkali metal sulfide such as sodium sulfide with elemental sulfur with a halogenated unsaturated hydrocarbon such as hexachlorobutadiene. From the viewpoint of obtaining a large charge-discharge capacity, the sulfur content in the polysulfide carbon compound is preferably 60% to 80% by mass, and more preferably 65% ​​to 75% by mass. As a method for producing polysulfide carbon, a method can be used in which a complex of an alkali metal sulfide such as sodium sulfide with elemental sulfur is reacted with a halogenated unsaturated hydrocarbon such as hexachlorobutadiene and then heat-treated. Such heat treatment is preferably carried out in a non-oxidizing atmosphere at a temperature range of 300°C to 450°C. The above non-oxidizing atmosphere refers to an atmosphere in which the oxygen concentration is less than 5% by volume, preferably an atmosphere in which the oxygen concentration is less than 2% by volume, and more preferably an atmosphere that is substantially free of oxygen, i.e., an inert gas atmosphere such as nitrogen, helium, or argon, or a sulfur gas atmosphere.

[0143] Among these sulfur-modified organic compounds, at least one selected from the group consisting of sulfur-modified polyacrylonitrile compounds, sulfur-modified elastomer compounds, and sulfur-modified polyether compounds is preferred from the viewpoint of obtaining a large charge / discharge capacity and stable cycle characteristics, and sulfur-modified polyacrylonitrile compounds are most preferred from the viewpoint of making the effects of the present invention more pronounced.

[0144] Furthermore, a sulfur-carbon composite can be used as the positive electrode active material. A sulfur-carbon composite is a material containing elemental sulfur within the pores of porous carbon, capable of intercalating and releasing lithium ions, and usable as an electrode active material for secondary batteries. If the sulfur content of the sulfur-carbon composite, in which elemental sulfur is supported within the pores of porous carbon, is too low, the charge / discharge capacity will not be large, and if it is too high, the electronic conductivity will decrease. Therefore, the sulfur content of the sulfur-carbon composite is preferably 25% to 80% by mass, and more preferably 30% to 70% by mass. Known methods can be used to support elemental sulfur within the pores of porous carbon.

[0145] In the battery of the present invention, the shape of the positive electrode active material is not particularly limited, but can be spherical, polyhedral, fibrous, rod-shaped, plate-shaped, flake-shaped, or amorphous, and these may be hollow. Among these, a spherical or polyhedral shape is preferred because it is easy to form a uniform coating film with the positive electrode mixture slurry.

[0146] If the average particle size (D50) of the positive electrode active material is too small, handling the powder becomes difficult; if it is too large, the uniformity and smoothness of the electrode decrease. Therefore, the average particle size (D50) of the positive electrode active material is preferably 1 nm or larger, more preferably 10 nm or larger, and even more preferably 50 nm or larger. Furthermore, the average particle size (D50) of the positive electrode active material is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. By setting the average particle size (D50) of the positive electrode active material within the above range, a stable and responsive positive electrode can be manufactured.

[0147] The amount of positive electrode active material in the positive electrode electrode mixture layer (hereinafter sometimes referred to as the "positive electrode mixture layer") is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Furthermore, the amount of positive electrode active material in the positive electrode mixture layer is preferably 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less. By setting the amount of positive electrode active material within the above range, the effects of the present invention become more pronounced.

[0148] C1-2. Binder Binders used in the positive electrode mixture layer include those that have the function of holding the positive electrode active material to the current collector or bonding the positive electrode active materials together. The battery of the present invention can use known binders used in non-aqueous electrolyte secondary batteries. Specific examples of binders include, for example, styrene-butadiene rubber (SBR), butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber (EPDM), styrene-isoprene rubber, fluororubber, polyethylene, polypropylene, polyacrylamide, polyamide, polyamide-imide, polyimide, polyacrylonitrile, polyurethane, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-acrylic acid copolymer, ethylene-vinyl alcohol copolymer, polymethyl methacrylate, polyacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, polyvinyl ether, polyvinyl chloride, acrylic acid, polyacrylic acid, methylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose nanofiber, starch, and the like. The binder may be used alone or in combination of two or more types. Among these, water-based binders are preferred from the viewpoint of having a low environmental impact and easily suppressing the leakage of positive electrode active material from the positive electrode to the electrolyte, and styrene-butadiene rubber, sodium carboxymethylcellulose, and polyacrylic acid are more preferred.

[0149] The amount of binder in the positive electrode mixture layer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of positive electrode active material. Furthermore, the amount of binder in the positive electrode mixture layer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of positive electrode active material. By setting the amount of binder within the above range, the stability of the electrode during repeated charge and discharge cycles is improved.

[0150] C1-3. Conductive additives The conductive additive used in the positive electrode mixture layer can be any additive that improves the conductivity of the positive electrode, and known conductive additives used in non-aqueous electrolyte secondary batteries can be used. Specific examples of conductive additives include, for example, carbon materials such as natural graphite, artificial graphite, coal tar pitch, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, roller black, disc black, carbon nanotubes, vapor-grown carbon fiber (VGCF), flake graphite, graphene, fullerene, and needle coke; metal powders such as aluminum powder, nickel powder, and titanium powder; conductive metal oxides such as zinc oxide and titanium oxide; and sulfides such as La2S3, Sm2S3, Ce2S3, and TiS2. Only one conductive additive may be used, or two or more may be used in combination.

[0151] The average particle size (D50) of the conductive additive is preferably 0.0001 μm or more, more preferably 0.0005 μm or more, and even more preferably 0.001 μm or more. Furthermore, the average particle size (D50) of the conductive additive is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. By setting the average particle size (D50) of the conductive additive within the above range, it becomes easier to obtain a positive electrode mixture layer with good conductivity and a smooth surface.

[0152] The amount of conductive additive in the positive electrode mixture layer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of positive electrode active material. Furthermore, the amount of conductive additive in the positive electrode mixture layer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of positive electrode active material. By setting the amount of conductive additive within the above range, it becomes easier to obtain a positive electrode mixture layer with good conductivity and a smooth surface.

[0153] C1-4. Organic Solvents When forming a positive electrode mixture layer by applying a positive electrode mixture slurry containing positive electrode active material, the positive electrode mixture slurry may contain an organic solvent. As the organic solvent, a known organic solvent used in non-aqueous electrolyte secondary batteries can be used, but it is preferable that the organic solvent adjusts the viscosity of the positive electrode mixture slurry containing the positive electrode active material and improves its applicability. Specific examples of organic solvents include, for example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, acetonitrile, propionitrile, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,3-dioxolane, nitromethane, N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N,N-dimethylaminopropylamine, polyethylene oxide, tetrahydrofuran, dimethyl sulfoxide, sulfolane, and γ-butyrolactone. In addition, water may be used instead of an organic solvent in a positive electrode mixture slurry containing a positive electrode active material.

[0154] The amount of organic solvent in the positive electrode mixture slurry containing the positive electrode active material can be adjusted according to the application method selected when applying the positive electrode mixture slurry. For example, in the case of application by the doctor blade method, the amount of organic solvent is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, per 100 parts by mass of positive electrode mixture slurry. Similarly, the amount of organic solvent is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 100 parts by mass or less, per 100 parts by mass of positive electrode mixture slurry. By setting the amount of organic solvent within the above range, good coatability is achieved and the electrode mixture layer is easily formed.

[0155] C1-5. Other ingredients When forming a positive electrode mixture layer by applying a positive electrode mixture slurry containing a positive electrode active material, the positive electrode mixture slurry may contain other components as long as it does not impair the effects of the present invention. Examples of other components include viscosity modifiers, reinforcing agents, leveling agents, antioxidants, pH adjusters, dispersants, etc. The positive electrode mixture slurry may contain not only the above-mentioned other components but also known components used in non-aqueous electrolyte secondary batteries. In the positive electrode mixture slurry, the above-mentioned other components and known components may be used in known blending ratios.

[0156] The viscosity modifiers mentioned above are those that adjust the viscosity of the positive electrode mixture slurry, and known viscosity modifiers used in non-aqueous electrolyte secondary batteries can be used. Specific examples of viscosity modifiers include, for example, those described in International Publication No. 2012 / 115096.

[0157] The reinforcing materials mentioned above include those that improve the strength of the electrodes or make them less prone to breakage, and known reinforcing materials used in non-aqueous electrolyte secondary batteries can be used. Specific examples of reinforcing materials include, for example, various inorganic and organic spherical, plate-shaped, rod-shaped, or fibrous fillers such as fumed silica and fumed alumina.

[0158] The leveling agent mentioned above is one that improves the coatability of the composition containing the positive electrode active material, and known leveling agents used in non-aqueous electrolyte secondary batteries can be used. Specific examples of leveling agents include, for example, the leveling agent described in International Publication No. 2012 / 115096.

[0159] The above-mentioned antioxidants include those that suppress oxidation of electrode materials or improve electrode life, and known antioxidants used in non-aqueous electrolyte secondary batteries can be used. Specific examples of antioxidants include, for example, the hindered phenol antioxidants and phosphite antioxidants described in International Publication No. 2019 / 172281.

[0160] The above-mentioned pH adjusting agent is one that adjusts the pH of a composition containing a positive electrode active material, and known pH adjusting agents used in non-aqueous electrolyte secondary batteries can be used. Specific examples of pH adjusting agents include, for example, the pH adjusting agent described in Japanese Patent Application Publication No. 2020-140957.

[0161] C1-6. Current collector The current collector is used as the material to be coated with the positive electrode mixture slurry, and can be used without particular limitations as long as it is a known material for current collectors of electrodes. Specific examples of current collectors include conductive materials such as titanium, titanium alloys, aluminum, aluminum alloys, copper, nickel, stainless steel, nickel-plated steel, carbon, and conductive resins. The shape of the current collector can be foil-like, plate-like, mesh-like, three-dimensional mesh-like, foam-like, or non-woven fabric-like, and the current collector may be porous or non-porous. Furthermore, these conductive materials may be surface-treated to improve adhesion and electrical properties. Among these conductive materials, aluminum is preferred from the viewpoint of stability at positive electrode potential, conductivity, and cost, and aluminum foil is more preferred. The thickness of the current collector is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. The thickness of the current collector is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. By setting the thickness of the current collector within the above-mentioned range, the charge and discharge capacity of the non-aqueous electrolyte secondary battery of the present invention is increased. From the viewpoint of increasing the discharge capacity of the non-aqueous electrolyte secondary battery of the present invention, it is preferable to use a porous conductive material as the current collector.

[0162] The diameter of the pores in the porous current collector is preferably 3 mm or less, more preferably 1 mm or less, and even more preferably 0.5 mm or less. The diameter of the pores in the porous current collector is preferably 0.01 mm or more, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more. By setting the diameter of the pores within the above range, the battery performance of the non-aqueous electrolyte secondary battery of the present invention is improved.

[0163] The number of holes in a porous current collector is 10 cm 2 Preferably, there is one or more holes, more preferably 10 or more, and even more preferably 20 or more. By setting the number of holes within the above range, the battery performance of the non-aqueous electrolyte secondary battery of the present invention becomes excellent.

[0164] C1-7. Others There are no particular limitations on the method for manufacturing a cathode using a cathode mixture slurry containing a cathode active material, but examples include the manufacturing method described in International Publication No. 2019 / 064538.

[0165] If the positive electrode mixture layer contains at least one of a sulfur-modified organic compound and a sulfur-carbon composite as the positive electrode active material, the positive electrode having the positive electrode mixture layer containing at least one of the sulfur-modified organic compound and the sulfur-carbon composite can be fabricated and then pre-doped with lithium before use. The pre-doping method can be any known method. For example, there are methods such as assembling a half-cell using metallic lithium as the counter electrode and inserting lithium by electrochemical doping using an electrolytic doping method, inserting lithium by attaching metallic lithium foil to the electrode and then leaving it in an electrolyte to utilize the diffusion of lithium into the electrode, and mechanical methods in which the active material and lithium metal are mechanically collided to insert lithium, but the method is not limited to these.

[0166] C2.Negative electrode The negative electrode that can be used in the battery of the present invention is not particularly limited as long as it is a known negative electrode used in non-aqueous electrolyte secondary batteries. Specific examples of negative electrodes include electrodes using an electrode mixture layer containing a negative electrode active material, and electrodes made of metal foil. The electrode mixture layer can include an electrode mixture layer containing a binder and a conductive additive in addition to the negative electrode active material. An electrode using an electrode mixture layer may consist only of the electrode mixture layer, or it may be a multilayer structure including a current collector, a conductive layer, a coating layer, etc. Methods for forming the electrode mixture layer include, for example, applying a negative electrode mixture slurry obtained by slurring a positive electrode active material, a binder, and a conductive additive with an organic solvent or water, and then drying it. In the battery of the present invention, from the viewpoint of easily obtaining a battery with a large electromotive force, it is preferable that the negative electrode is an electrode using an electrode mixture layer.

[0167] C2-1.Negative electrode active material The negative electrode active material can be any known negative electrode active material used in non-aqueous electrolyte secondary batteries. Specific examples of negative electrode active materials include, for example, natural graphite, artificial graphite, non-graphitizable carbon, easily graphitizable carbon, lithium, lithium alloys, silicon, silicon alloys, silicon oxide, tin, tin alloys, tin oxide, phosphorus, germanium, indium, copper oxide, antimony sulfide, titanium oxide, iron oxide, manganese oxide, cobalt oxide, nickel oxide, lead oxide, ruthenium oxide, tungsten oxide, zinc oxide, as well as LiVO2, Li2VO4, Li4Ti5O 12 Examples include composite oxides such as titanium niobium oxides. The negative electrode active material may be used alone or in combination of two or more types.

[0168] As the negative electrode active material, sulfur-modified organic compounds and sulfur-carbon composites described in "C1-1. Positive Electrode Active Material" above can also be used.

[0169] If the average particle size (D50) of the negative electrode active material is too large, a uniform and smooth electrode mixture layer may not be obtained, and if it is too small, handling in the slurrying process will be reduced. Therefore, the average particle size (D50) of the negative electrode active material is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 1 μm or more. The average particle size (D50) of the negative electrode active material is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. By setting the average particle size (D50) of the negative electrode active material within the above range, a stable and responsive negative electrode can be manufactured.

[0170] The negative electrode active material can be processed to a desired particle size by methods such as grinding. Grinding may be performed by dry grinding in a gas or wet grinding in a liquid such as water. Examples of industrial grinding methods include ball mills, roller mills, turbo mills, jet mills, cyclone mills, hammer mills, pin mills, rotary mills, vibratory mills, planetary mills, attritors, and bead mills.

[0171] The amount of negative electrode active material in the negative electrode electrode mixture layer (hereinafter sometimes referred to as the "negative electrode mixture layer") is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Furthermore, the amount of negative electrode active material in the negative electrode mixture layer is preferably 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less. By setting the amount of negative electrode active material within the above range, the charge and discharge capacity of the non-aqueous electrolyte secondary battery of the present invention is increased.

[0172] C2-2. Binder The binder used in the negative electrode mixture layer is not particularly limited, as long as it is a known binder used in non-aqueous electrolyte secondary batteries. Specific examples of binders include those similar to those used in the positive electrode. The binder may be used alone or in combination of two or more types.

[0173] The amount of binder in the negative electrode mixture layer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of negative electrode active material. Furthermore, the amount of binder in the negative electrode mixture layer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of negative electrode active material. By setting the amount of binder within the above range, the stability of the electrode during repeated charge and discharge cycles is improved.

[0174] C2-3. Conductive additives The conductive additive used in the negative electrode mixture layer can be any additive that improves the conductivity of the negative electrode, and known conductive additives used in non-aqueous electrolyte secondary batteries can be used. Specific examples of conductive additives include those similar to those used in the positive electrode mixture layer. Only one type of conductive additive may be used, or two or more types may be used in combination.

[0175] The amount of conductive additive in the negative electrode mixture layer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the negative electrode active material. Furthermore, the amount of conductive additive in the negative electrode mixture layer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the negative electrode active material. By setting the amount of conductive additive within the above range, it becomes easier to obtain a negative electrode mixture layer with good conductivity and a smooth surface.

[0176] C2-4. Organic Solvents When forming a negative electrode mixture layer by coating a negative electrode mixture slurry containing a negative electrode active material, the negative electrode mixture slurry may contain an organic solvent. The organic solvent is not particularly limited as long as it is a known organic solvent used in non-aqueous electrolyte secondary batteries. Specific examples of organic solvents include those similar to those used in the positive electrode mixture slurry containing the positive electrode active material described above. Furthermore, water may be used instead of the organic solvent in the negative electrode mixture slurry containing the negative electrode active material. The amount of organic solvent can be the same as that used in the positive electrode mixture slurry containing the positive electrode active material.

[0177] C2-5. Other ingredients When a negative electrode mixture slurry containing a negative electrode active material is applied to form a negative electrode mixture layer, the negative electrode mixture slurry may contain other components as long as the effects of the present invention are not impaired. Examples of other components include those similar to those described for the positive electrode mixture slurry containing a positive electrode active material.

[0178] C2-6. Current collector The negative electrode current collector can be the same type used for the positive electrode.

[0179] C2-7. Others The method for manufacturing a negative electrode using a negative electrode mixture slurry containing a negative electrode active material is not particularly limited, but it can be the same as the method for manufacturing a positive electrode using a positive electrode mixture slurry containing a positive electrode active material.

[0180] When the negative electrode active material is a metal or metal alloy such as lithium, lithium alloy, tin, or tin alloy, the metal or alloy can also be used as the negative electrode in the form of a plate, sheet, or film. In this case, a binder, conductive additive, or solvent is not required. Furthermore, when using the above-mentioned metal or metal alloy as the negative electrode active material, a current collector may not be necessary because the electronic conductivity of the negative electrode active material itself is high. However, depending on the battery configuration, a metal material that does not form an alloy with the negative electrode active material can also be used as the current collector.

[0181] C3. Separator In the battery of the present invention, it is preferable that a separator is interposed between the positive electrode and the negative electrode. The separator is not particularly limited as long as it is a known separator used in non-aqueous electrolyte secondary batteries. Specific examples of separators include, for example, polymer compounds and derivatives mainly composed of polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyethers such as polyethylene oxide and polypropylene oxide, various celluloses such as carboxymethylcellulose and hydroxypropylcellulose, poly(meth)acrylic acid and its various esters, and films made of copolymers and mixtures thereof. These films may be coated with ceramic materials such as alumina and silica, magnesium oxide, aramid resin, or polyvinylidene fluoride.

[0182] The film used as a separator may be used as a single layer or as a multi-layered film by overlapping multiple films. In the battery of the present invention, from the viewpoint of being a relatively inexpensive material, the film used as a separator is preferably made of polyethylene, polypropylene, polyvinylidene fluoride, or polysulfone.

[0183] The film used as a separator is preferably microporous so that electrolytes can easily permeate and ions can easily pass through. Methods for creating this microporous film include the "phase separation method," in which a film is formed while microphase-separating a solution of polymer compound and solvent, and the solvent is extracted and removed to create porosity; and the "stretching method," in which a film is formed by extruding a molten polymer compound under a high fume hood, followed by heat treatment to align the crystals in one direction, and then stretching to create gaps between the crystals and create porosity. These microporous film creation methods are appropriately selected depending on the type of film, etc.

[0184] C4. External packaging The shape of the battery of the present invention is not particularly limited, and can be a variety of shapes such as coin-type batteries, cylindrical batteries, prismatic batteries, laminated batteries, etc., and a metal container or laminated film can be used as the external packaging material. The thickness of the external packaging material is usually 0.5 mm or less, preferably 0.3 mm or less. Examples of external packaging material shapes include flat (thin), prismatic, cylindrical, coin-type, button-type, etc.

[0185] Examples of metal containers include those made from stainless steel, aluminum, or aluminum alloys. For aluminum alloys, alloys containing elements such as magnesium, zinc, and silicon are preferred. By reducing the content of transition metals such as iron, copper, nickel, and chromium in aluminum or aluminum alloys to 1% by mass or less, long-term reliability and heat dissipation in high-temperature environments can be dramatically improved.

[0186] The laminate film can be a multilayer film having a metal layer between resin films. For weight reduction, aluminum foil or aluminum alloy foil is preferred for the metal layer. The resin film can be, for example, a polymer material such as polypropylene, polyethylene, nylon, or polyethylene terephthalate. The laminate film can be sealed by heat fusion to form an exterior component.

[0187] C5. Others Other components include, for example, terminals, insulating plates, lead plates, and overcurrent protection elements, and these can be components of known non-aqueous electrolyte secondary batteries as appropriate.

[0188] C6. Uses of batteries Applications of the battery of the present invention include, for example, power sources for portable electronic devices such as smartphones, portable personal computers, and handheld video cameras; power sources for hybrid or electric vehicles; and renewable energy storage batteries.

[0189] Figure 1 shows an example of a coin-type non-aqueous electrolyte secondary battery of the present invention, Figures 2 and 3 show an example of a cylindrical non-aqueous electrolyte secondary battery, and Figures 4 to 6 show an example of a laminate-type non-aqueous electrolyte secondary battery.

[0190] In the coin-type non-aqueous electrolyte secondary battery 10 shown in Figure 1, 1 is a positive electrode mixture layer capable of releasing lithium ions, 1a is a positive electrode current collector, 2 is a negative electrode mixture layer capable of intercepting and releasing lithium ions released from the positive electrode, 2a is a negative electrode current collector, 3 is a non-aqueous electrolyte, 4 is a positive electrode case with stainless steel external packaging, 5 is a negative electrode case with stainless steel external packaging, 6 is a polypropylene gasket, and 7 is a polyethylene separator. In this example, the positive electrode includes a positive electrode composite layer 1 and a positive electrode current collector 1a, and the negative electrode includes a negative electrode composite layer 2 and a negative electrode current collector 2a.

[0191] In the cylindrical non-aqueous electrolyte secondary battery 10' shown in Figures 2 and 3, 11 is the negative electrode mixture layer, 12 is the negative electrode current collector, 13 is the positive electrode mixture layer, 14 is the positive electrode current collector, 15 is the non-aqueous electrolyte, 16 is the separator, 17 is the positive electrode terminal, 18 is the negative electrode terminal, 19 is the negative electrode plate, 20 is the negative electrode lead, 21 is the positive electrode plate, 22 is the positive electrode lead, 23 is the external packaging case, 24 is the insulating plate, 25 is the gasket, 26 is the safety valve, and 27 is the PTC element. In this example, the positive electrode includes a positive electrode composite layer 13 and a positive electrode current collector 14, and the negative electrode includes a negative electrode composite layer 11 and a negative electrode current collector 12.

[0192] Figure 4 is a schematic exploded perspective view showing the electrode group 29 of a laminate-type non-aqueous electrolyte secondary battery 28. In the embodiments described later, a laminate-type non-aqueous electrolyte secondary battery will be used for explanation, but the present invention is not limited thereto. The electrode group 29 has a structure in which, for example, a sheet-like negative electrode mixture layer 11, a sheet-like positive electrode mixture layer 13, and a sheet-like separator 16 that separates the negative electrode mixture layer 11 and the positive electrode mixture layer 13 are alternately stacked. 17 is the positive electrode terminal, and 18 is the negative electrode terminal. In this example, the positive electrode includes a positive electrode composite layer 13, and the negative electrode includes a negative electrode composite layer 11.

[0193] Figure 5 is a schematic exploded perspective view of a laminate-type non-aqueous electrolyte secondary battery 28, and Figure 6 is a schematic plan view of the laminate-type non-aqueous electrolyte secondary battery 28. 17 is the positive electrode terminal, 18 is the negative electrode terminal, 29 is the electrode group, 30 is the case-side laminate film of the external packaging, and 31 is the lid-side laminate film of the external packaging.

[0194] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. The present invention can be implemented in various forms with modifications, improvements, etc., that can be made by those skilled in the art, without departing from the spirit of the invention. [Examples]

[0195] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. Examples 3, 4, 7, and 8 are for reference only.

[0196] [Compounds to be added to non-aqueous electrolytes] Compound 1-1: 4-(methylsulfonyl)morpholine Compound 1-2: 2,6-dimethyl-4-(methylsulfonyl)morpholine Compound 2-1: Ethyl-α-methyl-2,4-dioxo-3-thiazolidinedacetate Compound 3-1: Cyclohexyl cyanoacetate Comparative compound 1: 1,3-propanesultone

[0197] [Preparation of non-aqueous electrolytes] Under conditions of 25°C, non-aqueous electrolytes for Examples 1-8 and Comparative Examples 2-3 were prepared by adding one of the above compounds 1-1, 1-2, 2-1, 3-1, and Comparative Compound 1 to a mixed solvent containing 36% by mass of ethylene carbonate, 64% by mass of ethyl methyl carbonate, and LiPF6 at a concentration of 1.0 mol / L, to the concentrations shown in Table 1 below. Comparative Example 1 was a non-aqueous electrolyte to which none of the above compounds were added. In the table, the mass % in parentheses indicates the amount of compound added relative to the non-aqueous electrolyte.

[0198] [Fabrication of the positive electrode] As a material for forming the positive electrode mixture layer, LiNi is used as the positive electrode active material. 8 / 10 CO 1 / 10 Mn 1 / 10 A positive electrode slurry was prepared by mixing 290 parts by mass of O, 5 parts by mass of acetylene black as a conductive additive, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder, and then dispersing the mixture in 140 parts by mass of N-methyl-2-pyrrolidone (NMP). This positive electrode slurry was applied to an aluminum current collector, dried, and then press-molded. Subsequently, this was cut to a predetermined size to produce a disc-shaped positive electrode.

[0199] [Fabrication of the negative electrode] As a material for forming the negative electrode mixture layer, 97.0 parts by mass of artificial graphite as the negative electrode active material, 1.5 parts by mass of styrene-butadiene rubber as a binder, and 1.5 parts by mass of carboxymethylcellulose as a viscosity modifier were mixed and dispersed in 120 parts by mass of water to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was applied onto a copper current collector, dried, and then press-molded. Subsequently, this was cut to a predetermined size to produce a disc-shaped negative electrode.

[0200] [Battery assembly] A 25 μm thick polyethylene microporous film was sandwiched between the positive and negative electrodes and held inside a case. As the non-aqueous electrolyte, one of the non-aqueous electrolytes from Examples 1-8 and Comparative Examples 1-3 listed in Table 1 was injected into the case, and the case was sealed to produce a non-aqueous electrolyte secondary battery (coin-type, φ20 mm, 3.2 mm thick).

[0201] [Cycle characteristics test] A non-aqueous electrolyte secondary battery is placed in a constant temperature bath at 25°C, and a charging current of 0.3 mA / cm² is applied. 2 Constant current charging up to 4.2V at a current equivalent to 0.2C (1C is the current value that discharges the battery capacity in 1 hour), with a discharge current of 1.5mA / cm. 2 The battery was stabilized by repeating a constant current discharge cycle down to 2.75V five times. The stabilized non-aqueous electrolyte secondary battery is placed in a constant temperature bath at 45°C, and a charging current of 1.5 mA / cm² is applied. 2 The battery is charged with a constant current up to 4.2V at a current equivalent to 1C (1C is the current value that discharges the battery capacity in 1 hour), and the discharge current is 1.5mA / cm. 2 The process involved repeatedly performing a constant current discharge until the voltage reached 2.75V 200 times. The discharge capacity ratio was calculated as the ratio (%) of the discharge capacity at the 200th charge-discharge cycle to the discharge capacity at the first charge-discharge cycle. The results are shown in Table 1. A larger discharge capacity ratio (%) indicates less decrease in charge capacity even after repeated charge-discharge cycles, and thus superior cycle characteristics.

[0202] [Table 1]

[0203] From Table 1, it was confirmed that the non-aqueous electrolyte secondary batteries using the non-aqueous electrolytes of Examples 1 to 8 to which the compounds represented by General Formulas (1) to (3) were added had a higher discharge capacity ratio and showed excellent cycle characteristics compared to the non-aqueous electrolyte secondary batteries using the non-aqueous electrolytes of Comparative Examples 1 to 3.

Explanation of Reference Signs

[0204] 1 Positive electrode mixture layer 1a Positive electrode current collector 2 Negative electrode mixture layer 2a Negative electrode current collector [[ID=N19]]3 Non-aqueous electrolyte 4 External package positive electrode case 5 External package negative electrode case 6 Gasket 7 Separator 10 Coin-type non-aqueous electrolyte secondary battery 10’ Cylindrical non-aqueous electrolyte secondary battery 11 Negative electrode mixture layer 12 Negative electrode current collector 13 Positive electrode mixture layer 14 Positive electrode current collector 15 Non-aqueous electrolyte 16 Separator 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode plate 22 Positive electrode lead 23 External package case 24 Insulating plate 25 Gasket 26 Safety valve 27 PTC element 28 Laminate-type non-aqueous electrolyte secondary battery 29 Electrode group 30 External package case-side laminate film 31 External package lid-side laminate film

Claims

1. A battery additive comprising at least one compound represented by the following general formula (1). 【Chemistry 1】 (In formula (1), R Ａ１ and R Ａ２ These are linked together to form a morpholine ring, R Ａ３ (This refers to an aliphatic hydrocarbon group with 1 to 3 carbon atoms.)

2. A non-aqueous electrolyte comprising at least one compound represented by the following general formula (1). 【Chemistry 2】 (In formula (1), R Ａ１ and R Ａ２ These are linked together to form a morpholine ring, R Ａ３ (This refers to an aliphatic hydrocarbon group with 1 to 3 carbon atoms.)

3. A non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and the non-aqueous electrolyte described in claim 2.

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