JP2023024398A - Non-aqueous electrolyte, and non-aqueous electrolyte battery using the same - Google Patents

Abstract

To provide a non-aqueous electrolyte capable of inhibiting increase in the internal resistance.SOLUTION: A non-aqueous electrolyte contains a compound (A) represented by formula (I), a cyclic carbonate (B) having a carbon-carbon unsaturated bond or fluorine atom, and a linear carboxylic acid ester (C).SELECTED DRAWING: None

Description

The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte battery using the same.

Energy devices represented by non-aqueous electrolyte batteries such as lithium-ion secondary batteries have been put to practical use in a wide range of applications, from so-called consumer power sources such as mobile phones and laptop computers to vehicle power sources for driving automobiles. It's getting However, in recent years, the demand for higher performance of non-aqueous electrolyte batteries has been increasing. Improvements in various battery characteristics are desired.
So far, as a means to improve the high-temperature storage characteristics and cycle characteristics of non-aqueous electrolyte secondary batteries, we have investigated various battery components such as positive and negative electrode active materials and non-aqueous electrolytes. technology is being considered.

In Patent Document 1, a specific vinylene carbonate compound and a specific vinylethylene sulfite are combined to suppress gas generation during continuous charging and to provide a lithium ion secondary battery having excellent discharge characteristics after continuous charging. A non-aqueous electrolyte for lithium ion secondary batteries containing
Patent document 2 provides a non-aqueous electrolyte secondary battery that suppresses an increase in internal resistance of the battery after high temperature storage and suppresses an increase in internal resistance of the battery when using the battery after high temperature storage at a low temperature. Therefore, a non-aqueous electrolyte secondary battery is disclosed which contains, as a non-aqueous electrolyte, 2 mass % or less of a specific cyclic unsaturated sultone compound and 2 mass % or less of a specific cyclic sulfite.

JP-A-2005-166553 JP 2010-92698 A

The inventors of the present invention have found that the non-aqueous electrolytes described in Patent Documents 1 and 2 have a fragile negative electrode film formed on the negative electrode, and that these non-aqueous electrolytes have a chain carboxylic acid with high reductive reactivity at the negative electrode. When an ester solvent is used, it is not possible to suppress the side reaction of the chain carboxylic acid ester solvent on the negative electrode at the initial stage of charge/discharge, and there is a problem that the effect of suppressing the increase in internal resistance is insufficient. I found

The present invention has been made to solve the above problems. An object of the present invention is to provide a non-aqueous electrolytic solution capable of suppressing an increase in resistance, and a non-aqueous electrolytic solution battery using the non-aqueous electrolytic solution.

In view of the above-mentioned circumstances, the present inventors have made intensive studies and found that a non-aqueous electrolytic solution containing a chain carboxylic acid ester further contains a specific cyclic sulfur-containing compound and a carbon-carbon unsaturated bond or a cyclic having a fluorine atom The inventors have found that the above problems can be solved by using a non-aqueous electrolytic solution containing carbonate, and have completed the present invention.
That is, the gist of the present invention is as follows.

[1] A non-aqueous electrolytic solution characterized by containing a compound (A) represented by formula (I), a cyclic carbonate (B), and a chain carboxylic acid ester (C),
A non-aqueous electrolytic solution in which the cyclic carbonate (B) is one or more selected from cyclic carbonates having a carbon-carbon unsaturated bond and cyclic carbonates having a fluorine atom.

(式（Ｉ）中、Ｘ^１及びＸ^２は、それぞれ独立に酸素原子又はＣＨ_２であり、Ｒ^１及びＲ^２は、それぞれ独立に水素原子、ハロゲン原子、又は炭化水素基であり、ｎは、１又は２である。ただし、Ｒ^１及びＲ^２のいずれか一方は、炭素－炭素不飽和結合を少なくとも一つ含む炭化水素基であり、ｎが２であるときは、Ｘ^１及びＸ^２の少なくとも一つがＣＨ_２である。)

(In formula (I), X ¹ and X ² are each independently an oxygen atom or CH ₂ , R ¹ and R ² are each independently a hydrogen atom, a halogen atom, or a hydrocarbon group, and n is , 1 or 2, provided that either one of R ¹ and R ² is a hydrocarbon group containing at least one carbon-carbon unsaturated bond, and when n is 2, X ¹ and X ² is _CH2 .)

[2] The non-aqueous electrolytic solution according to [1], wherein the compound (A) is a compound represented by the following formula (II).

(式（ＩＩ）中、Ｒ^１及びＲ^２は、前記式（Ｉ）中のＲ^１及びＲ^２と同じである。)
［３］Ｒ^１及びＲ^２が、それぞれ独立に、水素原子、ハロゲン原子、ビニル基、及びアリル基から選択される１つであり、Ｒ^１及びＲ^２のいずれか一方は、ビニル基及びアリル基から選択される、［１］又は［２］に記載の非水系電解液。
［４］前記化合物（Ａ）を０．０１質量％以上１０質量％以下含有する、［１］～［３］のいずれかに記載の非水系電解液。
［５］環状カーボネート（Ｂ）が、ビニレンカーボネート及び／又はフルオロエチレンカーボネートである、［１］～［４］のいずれかに記載の非水系電解液。
［６］環状カーボネート（Ｂ）を０．００１質量％以上１０質量％以下含有する、［１］～［５］のいずれかに記載の非水系電解液。
［７］前記鎖状カルボン酸エステル（Ｃ）が酢酸メチル又はプロピオン酸メチルである、［１］～［６］のいずれかに記載の非水系電解液。
［８］前記非水系溶媒中の前記鎖状カルボン酸エステル（Ｃ）の含有量が１体積％以上７０体積％以下である、［１］～［７］のいずれかに記載の非水系電解液。
［９］金属イオンを吸蔵及び放出しうる正極活物質を有する正極と、金属イオンを吸蔵及び放出しうる負極活物質を有する負極と、［１］～［８］のいずれかに記載の非水系電解液と、を備える非水系電解液電池。

(In formula (II), R ¹ and R ² are the same as R ¹ and R ² in formula (I) above.)
[3] R ¹ and R ² are each independently one selected from a hydrogen atom, a halogen atom, a vinyl group, and an allyl group, and either one of R ¹ and R ² is a vinyl group or allyl The non-aqueous electrolytic solution according to [1] or [2], which is selected from groups.
[4] The non-aqueous electrolytic solution according to any one of [1] to [3], containing 0.01% by mass or more and 10% by mass or less of the compound (A).
[5] The non-aqueous electrolytic solution according to any one of [1] to [4], wherein the cyclic carbonate (B) is vinylene carbonate and/or fluoroethylene carbonate.
[6] The non-aqueous electrolytic solution according to any one of [1] to [5], containing 0.001% by mass or more and 10% by mass or less of the cyclic carbonate (B).
[7] The non-aqueous electrolytic solution according to any one of [1] to [6], wherein the chain carboxylic acid ester (C) is methyl acetate or methyl propionate.
[8] The non-aqueous electrolytic solution according to any one of [1] to [7], wherein the content of the chain carboxylic acid ester (C) in the non-aqueous solvent is 1% by volume or more and 70% by volume or less. .
[9] A positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions, and the non-aqueous system according to any one of [1] to [8]. A non-aqueous electrolyte battery comprising an electrolyte.

According to the present invention, a non-aqueous electrolyte that can suppress an increase in internal resistance by using it in a non-aqueous electrolyte battery despite containing a carboxylic acid ester with high reductive reactivity at the negative electrode as a non-aqueous solvent. can provide. Also, a non-aqueous electrolyte battery including the non-aqueous electrolyte can be provided.

[1. Non-aqueous electrolyte]
The non-aqueous electrolyte of the present invention is a non-aqueous electrolyte for non-aqueous electrolyte batteries,
Compound (A) represented by formula (I) (hereinafter also referred to as "compound (A)"), and one or more selected from cyclic carbonates having a carbon-carbon unsaturated bond and cyclic carbonates having a fluorine atom It contains a cyclic carbonate (B) (hereinafter also referred to as "carbonate compound (B)") and a chain carboxylic acid ester (C).

The present inventor presumes the reason why the non-aqueous electrolytic solution having the structure of the present invention exhibits excellent effects as follows. As the non-aqueous electrolyte battery is charged and discharged, the compound (A) and the carbonate compound (B) react, and when forming a film on the electrode, the chain carboxylic acid ester (C) reacts with the electrode. It is believed that the reaction of the product produced by the reaction with the coating forms a strong co-coating with high polarity, which can suppress the side reaction between the electrode active material and the solvent or the like.

[1-1. Compound (A)]

In formula (I), X ¹ and X ² are each independently an oxygen atom or CH ₂ , R ¹ and R ² are each independently a hydrogen atom, a halogen atom, or a hydrocarbon group, and n is 1 or 2. provided that either one of R ¹ and R ² is a hydrocarbon group containing at least one carbon-carbon unsaturated bond, and when n is 2, at least one of X ¹ and X ² is CH ₂ ; be.

Among these, X ¹ is an oxygen atom, X ² is an oxygen atom, and n is 1; a sulfite ester structure in which X ¹ is an oxygen atom, X ² is CH ₂ , and n is 2; is preferred, and a sulfite ester structure in which ^X1 is an oxygen atom, ^X2 is an oxygen atom, and n is 1 is more preferred.

Either one of R ¹ and R ² is a hydrocarbon group containing at least one carbon-carbon unsaturated bond. Hydrocarbon groups containing at least one carbon-carbon unsaturated bond include alkenyl groups having 2 to 8 carbon atoms, alkynyl groups having 2 to 8 carbon atoms, aryl groups having 4 to 12 carbon atoms, or 7 to 10 carbon atoms. and an aralkyl group of Aryl groups and aralkyl groups include heteroaryl groups and heteroaralkyl groups in which any carbon atom constituting an aromatic ring is substituted with a heteroatom. When R ¹ and R ² are a hydrocarbon group containing a carbon-carbon unsaturated bond, an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 2 to 8 carbon atoms is preferable, and an alkenyl group having 2 to 8 carbon atoms is preferable. more preferred.
When R ¹ and R ² are saturated hydrocarbon groups, examples of hydrocarbon groups include alkyl groups having 1 to 10 carbon atoms.

Alkenyl groups include vinyl, allyl, methallyl, 2-butenyl, 3-methyl-2-butenyl, 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, and 7 -octenyl group and the like. Among them, an alkenyl group having 2 to 6 carbon atoms is preferred, and a vinyl group and an allyl group are more preferred, from the viewpoint of solubility in the electrolytic solution.

Examples of alkynyl groups include ethynyl, 2-propynyl, 2-butynyl, 3-butynyl, 4-pentynyl, 5-hexynyl, 6-heptynyl, and 7-octynyl groups. Among them, an alkynyl group having 2 to 6 carbon atoms is preferable, and an ethynyl group is more preferable, from the viewpoint of solubility in an electrolytic solution.

Aryl groups include phenyl, 1-naphthyl, 2-naphthyl, 2-thienyl, 3-thienyl, 2-furyl, 3-furyl, 2-pyrrolyl, 3-pyrrolyl, and benzyl and the like. Among them, an aryl group having 6 to 12 carbon atoms is preferred, and a phenyl group is more preferred, from the viewpoint of solubility in the electrolytic solution.

Aralkyl groups include benzyl, phenethyl, phenylpropyl, phenylbutyl, and phenylisopropyl groups. Among them, a benzyl group and a phenethyl group are preferable, and a benzyl group is more preferable, from the viewpoint of solubility in an electrolytic solution.

Alkyl groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, n-pentyl, hexyl, heptyl, octyl, nonyl, and decyl. and the like. Among them, an alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group, an ethyl group, and an iso-propyl group are more preferable from the viewpoint of solubility in an electrolytic solution.

R ¹ and R ² in formula (I) may combine to form a cyclic structure. The cyclic structure includes unsaturated carbocyclic rings other than aromatic rings such as cyclohexene ring and cyclopentene ring. Among them, a cyclohexene ring is preferable from the viewpoint of stability to the electrolytic solution.

Further, when R ¹ or R ² is a hydrocarbon group, carbon atoms in the hydrocarbon group may be substituted with oxygen atoms, and hydrogen atoms may be substituted with halogen atoms. A halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

Since compound (A) tends to react on the electrode and tend to be multimerized, R ¹ and R ² in formula (I) are preferably each independently a hydrogen atom, a halogen atom, a vinyl group, and one selected from an allyl group, and either one of R ¹ and R ² is selected from a vinyl group and an allyl group; Among them, a combination in which one of R ¹ and R ² is a vinyl group and the other is a hydrogen atom is preferable.

Among the compounds (A) represented by the formula (I), compounds represented by the following formula (II) having a sulfite ester structure in which X ¹ is an oxygen atom, X ² is an oxygen atom, and n is 1 are preferred. .

In formula (II), R ¹ and R ² have the same definitions as R ¹ and R ² in formula (I).

Specific examples of the compound represented by formula (II) include compounds represented by the following structural formulas.

Among the above compounds, compounds represented by the following structural formulas are preferable as the compound represented by formula (II).

Among the compounds represented by the above formula (II), compounds represented by the following structural formulas are more preferred.

Among the compounds represented by the above formula (II), compounds represented by the following structural formulas are more preferred.

Among the compounds represented by formula (II) above, compounds represented by the following structural formulas are particularly preferred.

Among the compounds represented by formula (II) above, compounds represented by the following structural formulas are most preferred.

Specific examples of the compound (A) represented by the formula (I) other than the compound represented by the formula (II) are shown below.

Specific examples of compounds having a sulfone structure in which X ¹ is CH ₂ , X ² is CH ₂ , and n is 2 in formula (I) include compounds represented by the following structural formulas.

In formula (I), the compound having a sulfonate ester structure in which X ¹ is an oxygen atom, X ² is CH ₂ , and n is 2 specifically includes compounds represented by the following structural formulas.

In formula (I), the compound having a sulfonate ester structure in which X ¹ is CH ₂ , X ² is an oxygen atom, and n is 2 specifically includes compounds represented by the following structural formulas.

(Content of compound (A))
The content of the compound (A) in the total amount (100% by mass) of the non-aqueous electrolytic solution is usually 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and further It is preferably 0.5% by mass or more, and usually 10% by mass or less, preferably 8% by mass or less, more preferably 6% by mass or less, and even more preferably 4% by mass or less. If the content of the compound (A) is within this range, it is possible to suppress an increase in internal resistance in the non-aqueous electrolyte battery. Compound (A) may be used singly or in combination of two or more in any desired ratio. Identification of compound (A) and measurement of content are performed by nuclear magnetic resonance (NMR) spectroscopy and/or gas chromatography.

(Mass ratio of compound (A) to electrolyte)
In the non-aqueous electrolytic solution, the mass ratio of the content of the compound (A) (the total amount in the case of two or more types) to the content of the electrolyte (compound (A) [g]/electrolyte [g]) is usually 0. 001 or more, preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.025 or more, still more preferably 0.03 or more, and usually 0.5 or less, preferably 0.3 or less , more preferably 0.2 or less, and still more preferably 0.1 or less. If the mass ratio is within this range, it is possible to remarkably suppress an increase in internal resistance, in particular, in a non-aqueous electrolyte battery. Although the principle of this effect is not clear, side reactions of the electrolyte in the battery system can be minimized by setting the mass ratio of the content of the compound (A) to the content of the electrolyte within this range. It is considered to be for

[1-2. Carbonate compound (B)]
The non-aqueous electrolytic solution contains at least one carbonate compound (B) selected from the group consisting of cyclic carbonates having a carbon-carbon unsaturated bond and cyclic carbonates having a fluorine atom. Among these, it preferably contains a cyclic carbonate having a carbon-carbon unsaturated bond, and more preferably contains vinylene carbonate. Moreover, these can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

(Content of carbonate compound (B))
The content of the carbonate compound (B) in the total amount (100% by mass) of the non-aqueous electrolyte (the total amount in the case of two or more types) is usually 0.001% by mass or more, preferably 0.01% by mass or more, and more It is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and is usually 10% by mass or less, preferably 5% by mass or less, more preferably 4% by mass or less, and still more preferably is 3% by mass or less. If the content of the carbonate compound (B) is within this range, it is possible to remarkably suppress increases in battery characteristics, particularly internal resistance. Although the principle of this effect is not clear, by containing the carbonate compound (B) in this ratio, a film is formed on the electrode, and side reactions of the components of the non-aqueous electrolytic solution can be minimized. it is conceivable that. Identification of the carbonate compound (B) and measurement of the content are performed by nuclear magnetic resonance (NMR) spectroscopy and/or gas chromatography.

(Mass ratio of carbonate compound (B) to compound (A))
The mass ratio (carbonate compound (B) [g]/compound (A) [g]) of the content of the carbonate compound (B) (the total amount when two or more are used) to the content of the compound (A) is usually 0.01 or more, preferably 0.05 or more, more preferably 0.3 or more, still more preferably 0.5 or more, and usually 100 or less, preferably 10 or less, more preferably 5 or less , more preferably 4 or less. If the mass ratio is within this range, it is possible to remarkably suppress an increase in battery characteristics, particularly internal resistance. Although the principle of this is not clear, by containing the compound (A) and the carbonate compound (B) in this mass ratio range, a film is formed on the electrode, and a side reaction of the components of the non-aqueous electrolytic solution is prevented. presumably because it can be minimized.

(Mass ratio of carbonate compound (B) to electrolyte)
In the non-aqueous electrolytic solution, the mass ratio of the content of the carbonate compound (B) (the total amount if two or more types) to the content of the electrolyte (carbonate compound (B) [g] / electrolyte [g]) is usually 0.00005 or more, preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.02 or more, particularly preferably 0.025 or more, and usually 0.5 or less, preferably 0.025 or more. It is 45 or less, more preferably 0.4 or less, still more preferably 0.35 or less. If the mass ratio is within this range, it is possible to remarkably suppress an increase in battery characteristics, particularly internal resistance. Although the principle of this effect is not clear, by containing the carbonate compound (B) and the electrolyte in this mass ratio range, a film is formed on the electrode, and side reactions of the electrolyte in the battery system are minimized. It is thought that this is because it can be suppressed to a limit.

[1-2-1. Cyclic carbonate having a carbon-carbon unsaturated bond]
The cyclic carbonate having a carbon-carbon unsaturated bond (hereinafter also referred to as "unsaturated cyclic carbonate") is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond. . A cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.

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

Specific examples of unsaturated cyclic carbonates include vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylene carbonate, phenylvinylene carbonate, 4,5-diphenylvinylene carbonate, vinylvinylene carbonate, 4,5-divinylvinylene carbonate, allyl Vinylene carbonates such as vinylene carbonate and 4,5-diallylvinylene carbonate;
Vinylethylene carbonate, 4,5-divinylethylene carbonate, 4-methyl-5-vinylethylene carbonate, 4-allyl-5-vinylethylene carbonate, ethynylethylene carbonate, 4,5-diethynylethylene carbonate, 4-methyl-5 -ethynylethylene carbonate, 4-vinyl-5-ethynylethylene carbonate, 4-allyl-5-ethynylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl -A substituent having an aromatic ring or a carbon-carbon double bond or a carbon-carbon triple bond such as 5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene carbonate, 4-methyl-5-allylethylene carbonate, etc. substituted ethylene carbonates; and the like.
Among these, vinylene carbonate, vinylethylene carbonate, and ethynylethylene carbonate are preferred because they form a more stable coating on the electrode, and more preferably one or more selected from vinylene carbonate and vinylethylene carbonate, and vinylene carbonate is even more preferred.
An unsaturated cyclic carbonate can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

[1-2-2. Cyclic carbonate having a fluorine atom]
The cyclic carbonate having a fluorine atom is not particularly limited as long as it has a cyclic carbonate structure and contains a fluorine atom.
Examples of the cyclic carbonate having a fluorine atom include fluorinated cyclic carbonates having an alkylene group having 2 to 6 carbon atoms, and derivatives thereof, such as fluorinated ethylene carbonate (fluoroethylene carbonate) and derivatives thereof, and Ethylene carbonate having a fluorine group can be mentioned. Derivatives of fluorinated ethylene carbonate include fluorinated ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms). Among these, fluoroethylene carbonate and derivatives thereof are preferred.

Fluoroethylene carbonate having 1 to 8 fluorine atoms and derivatives thereof, and ethylene carbonate having a fluorine-containing group include monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro- 4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylene carbonate, 4-(trifluoromethyl)-ethylene carbonate, 4-(fluoromethyl)-4-fluoroethylene carbonate, 4-(fluoromethyl)-5-fluoroethylene carbonate, 4-fluoro -4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate and the like. Among these, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, and 4,5-difluoroethylene carbonate are used from the viewpoint of imparting high ionic conductivity to the electrolytic solution and facilitating the formation of a stable interfacial protective film. One or more selected are preferred.
Cyclic carbonates having a fluorine atom can be used singly or in combination of two or more at any ratio.

[1-3. Chain carboxylic acid ester (C)]
Examples of chain carboxylic acid esters (C) include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, methyl valerate, methyl isobutyrate, iso Ethyl butyrate, and methyl pivalate. Among these, from the viewpoint of ease of reaction with the electrode, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, and ethyl propionate are preferable, and methyl acetate or methyl propionate is more preferable. is more preferred. Chain carboxylic acid esters (eg, methyl trifluoroacetate, ethyl trifluoroacetate, etc.) obtained by substituting a portion of the hydrogen atoms of the above compounds with fluorine atoms can also be suitably used.

The content of the chain carboxylic acid ester (C) in the non-aqueous electrolytic solution is usually 1% by volume or more, preferably 5% by volume or more, more preferably 15% by volume or more, from the viewpoint of suppressing an increase in internal resistance. Yes, usually 70% by volume or less, preferably 50% by volume or less, more preferably 40% by volume or less. In addition, volume % in this specification means volume % at 25 degreeC and 1 atmospheric pressure.
When the content of the chain carboxylic acid ester with respect to the total amount of the non-aqueous solvent is converted on a mass basis, it is usually 0.8% by mass or more, preferably 4% by mass or more, more preferably 13% by mass or more, and usually 63% by mass. % or less, preferably 44 mass % or less, more preferably 35 mass % or less.

[1-4. Electrolytes]
Examples of the electrolyte in the non-aqueous electrolytic solution include lithium salts. The lithium salt is not particularly limited, and any one can be used. Examples include lithium fluoroborate, lithium fluorophosphate, lithium tungstate, lithium carboxylate, lithium sulfonate, and lithium imide. , lithium methide salts, lithium oxalate salts, and fluorine-containing organic lithium salts.

Among these, from the viewpoint of improving low-temperature output characteristics, high-rate charge/discharge characteristics, impedance characteristics, high-temperature storage characteristics, cycle characteristics, etc., LiBF ₄ as a lithium fluoroborate; LiPF ₆ and Li ₂ PO ₃ as lithium fluorophosphates. F, LiPO ₂ F ₂ ; LiSO ₃ F, LiCH ₃ SO ₃ as lithium sulfonate salts; LiN(FSO ₂ ) ₂ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) as lithium imide salts ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide; as the lithium methide salt, LiC(FSO ₂ ) ₃ , LiC(CF ₃ SO ₂ ) ₃ , LiC(C ₂ F ₅ SO ₂ ) ₃ ; lithium oxalate salts such as lithium difluorooxalate borate, lithium bis(oxalate) borate, lithium tetrafluorooxalate phosphate, lithium difluorobis (oxalate) phosphate, lithium tris(oxalate) phosphate, etc. are preferred, one or more selected from LiPF ₆ , LiN(FSO ₂ ) ₂ , lithium bis(oxalate) borate and LiSO ₃ F are more preferred, and LiPF ₆ is particularly preferred. .

The above electrolytes can be used singly or in combination of two or more at any ratio.
The combination of two or more electrolytes is not particularly limited, and may be a combination of _LiPF6 and LiN( _FSO2 ) ₂ , a combination of _LiPF6 and _LiBF4 , a combination _{of LiPF6} and LiN( _CF3SO2 ) ₂ , _LiBF4 and A combination of LiN(FSO ₂ ) ₂ , a combination of LiBF ₄ , LiPF ₆ and LiN(FSO ₂ ) ₂ and the like are included. Among these, a combination of LiPF ₆ and LiN(FSO ₂ ) ₂ , a combination of LiPF ₆ and LiBF ₄ , and a combination of LiBF ₄ , LiPF ₆ and LiN(FSO ₂ ) ₂ are preferred.

The total concentration of the electrolyte is not particularly limited, but from the viewpoint of proper electrical conductivity and sufficient output characteristics, it is usually 8% by mass or more, preferably 8% by mass or more, based on the total amount of the non-aqueous electrolyte. It is 8.5% by mass or more, more preferably 9% by mass or more, and is usually 18% by mass or less, preferably 17% by mass or less, more preferably 16% by mass or less. Electrolyte identification and content determination are performed using magnetic resonance (NMR) spectroscopy and/or ion chromatography.

[1-5. Non-aqueous solvent]
The non-aqueous electrolytic solution contains a non-aqueous solvent, like common non-aqueous electrolytic solutions. The non-aqueous solvent to be used is not particularly limited as long as it dissolves the electrolyte when used in combination with the chain carboxylic acid ester (C), and a known organic solvent can be used.
Examples of the organic solvent include saturated cyclic carbonates (“excluding the carbonate compound (B)”, hereinafter the same), chain carbonates, cyclic carboxylic acid esters, cyclic ether compounds, and sulfone compounds. Not limited.

An organic solvent can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.
The combination of two or more organic solvents and the chain carboxylic acid ester (C) is not particularly limited, but a combination of a saturated cyclic carbonate and a chain carboxylic acid ester (C), a cyclic carboxylic acid ester, a chain carbonate and Combinations of chain carboxylic acid esters (C), combinations of saturated cyclic carbonates, chain carbonates and chain carboxylic acid esters (C), and the like are included. Among these, a combination of a saturated cyclic carbonate and a chain carbonate (C) and a combination of a saturated cyclic carbonate, a chain carbonate and a chain carboxylic acid ester (C) are preferred, and a saturated cyclic carbonate, a chain carbonate and a chain carbonate are preferred. A combination of methyl acetate as the carboxylic acid ester (C) is more preferred.

[1-5-1. saturated cyclic carbonate]
Examples of saturated cyclic carbonates include those having an alkylene group having 2 to 4 carbon atoms. Cyclic carbonates are preferred.
Specific examples of saturated cyclic carbonates include ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate or propylene carbonate is preferred, and ethylene carbonate, which is difficult to be oxidized/reduced, is more preferred. A saturated cyclic carbonate can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

The content of the saturated cyclic carbonate is not particularly limited, and is arbitrary as long as it does not impair the effects of the invention according to this embodiment. The content of the saturated cyclic carbonate is usually 3% by volume or more, preferably 5% by volume or more, more preferably 10% by volume or more, and usually 90% by volume or less, preferably is 85% by volume or less, more preferably 80% by volume or less. By setting this range, it is possible to avoid a decrease in electrical conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte, and the large current discharge characteristics of the non-aqueous electrolyte battery, the stability to the negative electrode, and the cycle characteristics are in a good range. and the oxidation/reduction resistance of the non-aqueous electrolytic solution is improved, and the stability during high-temperature storage tends to be improved.

[1-5-2. chain carbonate]
Examples of chain carbonates include chain carbonates having 3 to 7 carbon atoms, and chain carbonates having 3 to 5 carbon atoms are preferred in order to adjust the viscosity of the non-aqueous electrolytic solution to an appropriate range.
Specific examples of chain carbonates include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, n-propyl isopropyl carbonate, ethylmethyl carbonate, methyl-n-propyl carbonate and the like. Among these, one or more selected from dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate are preferable, and dimethyl carbonate is more preferable.
Chain carbonates having a fluorine atom (hereinafter also referred to as "fluorinated chain carbonate") can also be used. The number of fluorine atoms in the fluorinated linear carbonate is not particularly limited as long as it is 1 or more, but is preferably 6 or less, more preferably 4 or less. When the fluorinated linear carbonate has a plurality of fluorine atoms, the plurality of fluorine atoms may be bonded to the same carbon or different carbons.
Fluorinated linear carbonates include fluorinated dimethyl carbonate derivatives such as fluoromethylmethyl carbonate; fluorinated ethylmethyl carbonate derivatives such as 2-fluoroethylmethyl carbonate; and fluorinated diethyl carbonates such as ethyl-(2-fluoroethyl) carbonate. derivatives; and the like.
A chain carbonate can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

The content of the chain carbonate is not particularly limited, but the viscosity of the non-aqueous electrolyte is set in an appropriate range, the decrease in ionic conductivity is suppressed, and the output characteristics of the non-aqueous electrolyte battery are improved. It is usually 15% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more, and usually 90% by volume or less, preferably 85% by volume or less, based on the total amount of the non-aqueous solvent in the electrolytic solution. Preferably, it is 80% by volume or less.

Furthermore, by combining a specific linear carbonate and ethylene carbonate in a specific content, the battery performance can be significantly improved.
For example, when dimethyl carbonate is selected as the specific chain carbonate, the content of ethylene carbonate is adjusted to improve high-temperature stability and suppress gas generation. It is usually 15% by volume or more, preferably 20% by volume or more, more preferably 25% by volume or more, and usually 45% by volume or less, preferably 40% by volume or less, more preferably 35% by volume, based on the total amount of the solvent in the liquid. The content of dimethyl carbonate is usually 20% by volume or more, preferably 25% by volume or more, more preferably 30% by volume or more, and usually 55% by volume or less, preferably 50% by volume or less. , more preferably 45% by volume or less.

[1-5-3. Cyclic carboxylic acid ester]
Cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone. Among these, γ-butyrolactone is more preferred. A cyclic carboxylic acid ester obtained by substituting a portion of the hydrogen atoms of the above compounds with fluorine atoms can also be preferably used.
When the non-aqueous electrolyte contains a cyclic carboxylic acid ester, the content of the non-aqueous solvent is the total amount of the non-aqueous solvent from the viewpoint of improving the electrical conductivity of the non-aqueous electrolyte and improving the large current discharge characteristics of the non-aqueous electrolyte battery. is usually 1% by volume or more, preferably 5% by volume or more, and more preferably 15% by volume or more. In addition, the upper limit of the content is to keep the viscosity of the non-aqueous electrolyte in an appropriate range, avoid a decrease in electrical conductivity, suppress an increase in negative electrode resistance, and improve the large current discharge characteristics of non-aqueous electrolyte batteries. from the viewpoint of making it a wide range, it is usually 70% by volume or less, preferably 50% by volume or less, more preferably 40% by volume or less.

[1-5-4. Cyclic ether compound]
Cyclic ether compounds include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1,4-dioxane cyclic ethers having 3 to 6 carbon atoms such as Some hydrogen atoms in the cyclic ether compound may be substituted with fluorine atoms.
Among these, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane and the like are preferable from the viewpoint of providing high ionic conductivity.

When the non-aqueous electrolytic solution contains a cyclic ether compound, its content is arbitrary as long as it does not impair the effects of the present invention, but usually 1% by volume or more with respect to the total amount of the non-aqueous solvent in the non-aqueous electrolytic solution, It is preferably 2% by volume or more, more preferably 3% by volume or more, and usually 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less. If the content of the cyclic ether-based compound is within the above range, the effect of improving the degree of dissociation of metal ions, especially lithium ions, by the cyclic ether-based compound and the ionic conductivity improvement derived from the viscosity reduction of the non-aqueous electrolyte is ensured. It's easy to do. In addition, when the negative electrode active material is a carbon-based material, it is possible to suppress the phenomenon in which the chain ether is co-inserted with metal ions, especially lithium ions, so that input/output characteristics and charge/discharge rate characteristics can be set within appropriate ranges. .

[1-5-5. Sulfone compound]
The sulfone-based compound is not particularly limited, and may be a cyclic sulfone or a chain sulfone. Cyclic sulfones generally have 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms, and chain sulfones generally have 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms. Although the number of sulfonyl groups in one molecule of the sulfone compound is not particularly limited, it is usually one or two.
Cyclic sulfones include trimethylenesulfones, tetramethylenesulfones, hexamethylenesulfones, etc., which are monosulfone compounds; and trimethylenedisulfones, tetramethylenedisulfones, hexamethylenedisulfones, etc., which are disulfone compounds. Among these, tetramethylenesulfones, tetramethylenedisulfones, hexamethylenesulfones, and hexamethylenedisulfones are more preferable, and tetramethylenesulfones (sulfolanes) are even more preferable, from the viewpoint of dielectric constant and viscosity.
As sulfolanes, sulfolane and sulfolane derivatives are preferred. As the sulfolane derivative, one in which one or more hydrogen atoms bonded to carbon atoms constituting a sulfolane ring are substituted with a fluorine atom, an alkyl group, or a fluorine-substituted alkyl group is preferable.
Among these, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,3-difluorosulfolane, 2-trifluoromethylsulfolane, 3-trifluoromethylsulfolane and the like have an ionic conductivity is preferable in terms of high input/output.

Chain sulfones include dimethylsulfone, ethylmethylsulfone, diethylsulfone, monofluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, pentafluoroethylmethylsulfone and the like. Among these, dimethylsulfone, ethylmethylsulfone, and monofluoromethylmethylsulfone are preferable because they improve the high-temperature storage stability of the non-aqueous electrolytic solution.
When the non-aqueous electrolyte contains a sulfone-based compound, its content is arbitrary as long as it does not impair the effects of the present invention, but from the viewpoint of improving high-temperature storage stability, On the other hand, it is usually 0.3% by volume or more, preferably 0.5% by volume or more, more preferably 1% by volume or more, and is usually 40% by volume or less, preferably 35% by volume or less, more preferably 30% by volume. % or less.

[1-6. Auxiliary agent]
Auxiliaries that may be contained in the non-aqueous electrolytic solution include compounds having an isocyanate group, organic compounds having an isocyanuric acid skeleton, sulfur-containing organic compounds, phosphorus-containing organic compounds, organic compounds having a cyano group, and silicon-containing compounds. , aromatic compounds, carboxylic acid anhydrides, borate anion-containing compounds, phosphate anion-containing compounds having PF bonds and P=O bonds, anion-containing compounds having S=O bonds, oxalate complex anion-containing compounds, etc. I can give an example. Examples thereof include compounds described in International Publication No. 2015/111676.
The content of the auxiliary agent is not particularly limited, and is arbitrary as long as it does not significantly impair the effects of the present invention. , More preferably 0.1% by mass or more, usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, particularly preferably less than 1% by mass be.

[2. Non-aqueous electrolyte battery]
The non-aqueous electrolyte battery of the present invention is a non-aqueous electrolyte battery comprising a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, and a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions. It is characterized by comprising the non-aqueous electrolytic solution of the present invention.
It should be noted that other non-aqueous electrolytic solutions can be mixed with the non-aqueous electrolytic solution of the present invention without departing from the gist of the present invention.
Examples of the non-aqueous electrolyte battery of the present invention include polyvalent cation batteries, metal-air secondary batteries, and secondary batteries using s-block metals other than the above. Non-aqueous electrolyte secondary batteries are preferred, and lithium An ion secondary battery is more preferred.

[2-1. Non-aqueous electrolyte]
As the non-aqueous electrolytic solution, the above non-aqueous electrolytic solution is used. It should be noted that other non-aqueous electrolytic solutions can be mixed with the non-aqueous electrolytic solution of the present invention without departing from the gist of the present invention.

[2-2. positive electrode]
The positive electrode has a positive electrode active material capable of intercalating and deintercalating metal ions on at least part of the current collector surface. The positive electrode active material is preferably a positive electrode active material capable of intercalating and deintercalating lithium ions, and preferably contains a lithium transition metal compound.

[2-2-1. Positive electrode active material]
The positive electrode active material (lithium transition metal compound) used for the positive electrode is described below.

[2-2-1-1. Lithium transition metal compound]
A lithium transition metal compound is a compound having a structure capable of desorbing and inserting lithium ions. things, etc. Among these, a phosphate compound or a lithium transition metal composite oxide is preferred, and a lithium transition metal composite oxide is more preferred.
Lithium-transition metal composite oxides include those belonging to a spinel structure that enables three-dimensional diffusion and those that belong to a layered structure that enables two-dimensional diffusion of lithium ions.

A lithium-transition metal composite oxide having a spinel structure is generally represented by the following formula (1).
_{LixM2O4 ( 1} )
(In formula (1), x is 1≤x≤1.5, and M represents one or more transition metal elements.)
Specific examples of the oxide represented by formula (1) include LiMn ₂ O ₄ , LiCoMnO ₄ , LiNi _0.5 Mn _1.5 O ₄ and LiCoVO ₄ .

A lithium-transition metal composite oxide having a layered structure is generally represented by the following formula (2).
Li1 _+yMO2 ( ₂ )
(In formula (2), y is -0.1 ≤ y ≤ 0.5, and M represents one or more transition metal elements.)
Specific examples of the oxide represented by formula (2) include LiCoO ₂ , LiNiO ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.80 Co _0.15 Al _0.05 O _{2 , LiNi0.33Co0.33Mn0.33O2 , Li1.05Ni0.33Co0.33Mn0.33O2 , LiNi0.5Co0.2Mn0.3O2 _ _ _ _ _ _ _ , Li1.05Ni0.5Co0.2Mn0.3O2 , LiNi0.6Co0.2Mn0.2O2 , LiNi0.8Co0.1Mn0.1O2 , _ _ _ _ _ _ LiNi0.91Co0.06Mn0.03O2 , LiNi0.91Co0.06Al0.03O2 , LiNi0.90Co0.03Al0.07O2 , Li1.05Ni _ _ _ _ _ _ 0.34Co0.33Mn0.33O2} and _{the like .}

Among these, from the viewpoint of improving battery capacity, a lithium-transition metal composite oxide having a layered structure is preferable, and a lithium-transition metal composite oxide represented by the following formula (3) is more preferable.
_{Lia1Nib1Mc1O2 ( 3 )}
(In formula (3), a1, b1 and c1 are respectively 0.90 ≤ a1 ≤ 1.10, 0.30 ≤ b1 ≤ 0.98, 0.02 ≤ c1 ≤ 0.70, and b1 + c1 = 1 M represents at least one element selected from the group consisting of Co, Mn, Al, Mg, Zr, Fe, Ti and Er.)
In formula (3), b1 is preferably 0.40 or more, more preferably 0.50 or more, and particularly preferably 0.60 or more.

In particular, from the viewpoint of structural stability of the lithium-transition metal composite oxide, a lithium-transition metal composite oxide represented by the following formula (4) is preferable.
_{Lia2Nib2Coc2Md2O2 ( 4 ) _}
(In formula (4), a2, b2, c2 and d2 are 0.90≤a2≤1.10, 0.30≤b2≤0.98, 0.01≤c2≤0.70 and 0.90≤a2≤0.98, respectively. 01 ≤ d2 ≤ 0.50, and b2 + c2 + d2 = 1. M represents at least one element selected from the group consisting of Mn, Al, Mg, Zr, Fe, Ti and Er.)
In the above formula (4), b2 is preferably 0.40 or more, more preferably 0.50 or more, and particularly preferably 0.60 or more. Moreover, d2 is preferably 0.01 or more, more preferably 0.10 or more.
Suitable examples _{of the} lithium- _transition metal composite oxide represented _by the _above formula (4) include _{LiNi0.85Co0.10Al0.05O2} and _{LiNi0.80Co0.15Al0.05O2 . , LiNi0.8Co0.1Mn0.1O2 , LiNi0.91Co0.06Mn0.03O2 , LiNi0.91Co0.06Al0.03O2 , LiNi0.90 _ _ _ _ _ Co0.03Al0.07O22 , Li1.05Ni0.34Co0.33Mn0.33O2 and the like . _}

In the above formulas (1) to (3), from the viewpoint of increasing the structural stability of the lithium-transition metal composite oxide and suppressing structural deterioration during repeated charging and discharging, M may contain Co, Mn, or Al. Preferably, it contains Co and Mn.
In the above formula (4), from the viewpoint of increasing the structural stability of the lithium-transition metal composite oxide and suppressing structural deterioration during repeated charging and discharging, M preferably contains Mn or Al, and contains Mn. is preferred.

[2-2-1-2. Foreign element introduction]
Moreover, the lithium-transition metal composite oxide may contain an element (heterogeneous element) other than the element contained in any one of the above formulas (1) to (4).

The positive electrode active material other than the lithium transition metal-based compound is not particularly limited as long as it can occlude and release metal ions, and known positive electrode active materials can be used.

[2-2-1-3. surface coating]
As the positive electrode, the above-mentioned positive electrode active material may be used in which a substance having a composition different from that of the positive electrode active material (surface adhering substance) adheres to the surface of the positive electrode active material.
Examples of the surface adhering substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate. These surface-attaching substances can be attached to the surface of the positive electrode active material by, for example, a method of dissolving or suspending them in a solvent, impregnating and adding them to the positive electrode active material, and drying the material.
The amount of the surface-attached substance is preferably 1 μmol/g or more, more preferably 10 μmol/g or more, and usually 1 mmol/g or less, relative to the positive electrode active material.
In the present specification, a positive electrode active material having the above-described surface-attached substance attached to its surface is also referred to as a "positive electrode active material."

[2-2-1-4. blend]
A positive electrode active material can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

[2-2-2. Configuration and Manufacturing Method of Positive Electrode]
A positive electrode using the positive electrode active material can be manufactured by a conventional method. That is, a positive electrode active material, a binder, and, if necessary, a conductive material, a thickening agent, and the like are dry-mixed to form a sheet, which is crimped to a positive electrode current collector, or these materials are mixed with a water-based The positive electrode is formed by a coating method of forming a positive electrode active material layer on the current collector by dissolving or dispersing the slurry in a liquid medium such as a solvent or an organic solvent to form a slurry, applying the slurry to the current collector, and drying the slurry. Obtainable. Further, for example, the positive electrode active material may be roll-molded into a sheet electrode, or may be compression-molded into a pellet electrode.
A case where the slurry is sequentially applied to the positive electrode current collector and dried will be described below.

[2-2-2-1. Content of positive electrode active material]
The content of the positive electrode active material in the positive electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[2-2-2-2. Electrode density]
The positive electrode active material layer obtained by coating and drying is preferably densified by hand pressing, roller pressing, or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer present on the current collector is usually 1.5 g/cm ³ or more and 4.5 g/cm ³ or less.

[2-2-2-3. Conductive material]
Any known conductive material can be used as the conductive material. Specific examples thereof include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon-based materials such as amorphous carbon such as needle coke; . The conductive material can be used singly or in combination of two or more at any ratio. The conductive material is used so as to be contained in the positive electrode active material layer generally in an amount of 0.01% by mass or more and 50% by mass or less.

[2-2-2-4. Binder]
As the binder used for manufacturing the positive electrode active material layer, when the positive electrode active material layer is formed by a coating method, the type is particularly limited as long as it is a material that dissolves or disperses in the liquid medium for slurry. not. For example, fluorine-based resins such as polyvinyl fluoride, polyvinylidene fluoride, and polytetrafluoroethylene; CN group-containing polymers such as polyacrylonitrile and polyvinylidene cyanide, etc., are selected from the viewpoints of weather resistance, chemical resistance, heat resistance, flame resistance, etc. preferable.
Mixtures, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, etc. of the above polymers can also be used. In addition, a binder can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.
When a resin is used as the binder, the weight average molecular weight of the resin is arbitrary as long as it does not impair the effects of the present invention, and is usually 10,000 or more and 3,000,000 or less. When the molecular weight is within this range, the strength of the electrode is improved, and the electrode can be suitably formed.
The content of the binder in the positive electrode active material layer is usually 0.1% by mass or more and 80% by mass or less.

[2-2-2-5. current collector]
The material of the positive electrode current collector is not particularly limited, and any known material can be used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, with aluminum being preferred.
Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. Among these, a metal foil or a metal thin film is preferred. Incidentally, the metal thin film may be appropriately formed in a mesh shape.
When the shape of the current collector of the positive electrode is plate-like, film-like, or the like, the thickness of the current collector is arbitrary, but is usually 1 μm or more and 1 mm or less.

[2-2-2-6. Thickness of positive electrode plate]
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the positive electrode active material layer obtained by subtracting the thickness of the current collector from the thickness of the positive electrode plate is On the other hand, it is usually 10 μm or more and 500 μm or less.

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

[2-3. negative electrode]
The negative electrode has a negative electrode active material on at least part of the current collector surface.
[2-3-1. Negative electrode active material]
The negative electrode active material used for the negative electrode is not particularly limited as long as it can electrochemically occlude and release metal ions. Specific examples include (i) a carbonaceous material, (ii) particles containing a metal element and/or metalloid element that can be alloyed with Li, (iii) a lithium-containing metal composite oxide material, and (iv) these and the like. Among these, (i) a carbon-based material, (ii) a metal element capable of being alloyed with Li and/or a metalloid element are included in that the cycle characteristics and safety are good and the continuous charge characteristics are also excellent. Preference is given to using a mixture of graphite particles and particles and (v) particles containing metallic and/or semi-metallic elements that can be alloyed with Li.
These can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.

[2-3-1-1. carbon-based materials]
(i) Carbon-based materials include natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite. Among these, natural graphite is preferred. Carbon-based materials can be used singly or in combination of two or more at any ratio.
Examples of natural graphite include scale-like graphite, scale-like graphite, and/or graphite particles obtained by subjecting these graphites to a treatment such as spheroidization and densification. Among these, spherical or ellipsoidal graphite particles subjected to a spheroidizing treatment are preferable from the viewpoint of the packing property or charge/discharge rate characteristics of the particles.
The volume average particle diameter (d50) of the graphite particles is usually 1 μm or more and 100 μm or less.

[2-3-1-2. Physical properties of carbonaceous materials]
The carbon-based material as the negative electrode active material preferably satisfies at least one of the characteristics such as physical properties and shape shown in the following (1) to (4), and may satisfy a plurality of items at the same time. more preferred.
(1) X-Ray Diffraction Parameter The d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction of the carbon-based material according to the Gakushin method is usually 0.335 nm or more and 0.360 nm or less. In addition, the crystallite size (Lc) of the carbon-based material determined by X-ray diffraction according to the Gakushin method is 1.0 nm or more.
(2) Volume-Based Average Particle Size The volume-based average particle size of the carbon-based material is the volume-based average particle size (median diameter) determined by a laser diffraction/scattering method, and is usually 1 μm or more and 100 μm or less.
(3) Raman R value and Raman half-value width The Raman R value of a carbon-based material is a value measured using an argon ion laser Raman spectroscopy, and is usually 0.01 or more and 1.5 or less.
The Raman half-value width of the carbon-based material near 1580 cm ⁻¹ is not particularly limited, but is usually 10 cm ⁻¹ or more and 100 cm ⁻¹ or less.
(4) BET Specific Surface Area The BET specific surface area of a carbon-based material is the value of the specific surface area measured using the BET method, and is usually 0.1 m ² ·g ⁻¹ or more and 100 m ² ·g ⁻¹ or less.
Two or more carbon-based materials having different properties may be contained in the negative electrode active material. The property referred to here indicates one or more properties selected from the group of X-ray diffraction parameter, volume-based average particle diameter, Raman R value, Raman half width and BET specific surface area.
Examples of containing two or more types of carbonaceous materials having different properties include that the volume-based particle size distribution is not symmetrical about the median diameter, and that two or more types of carbonaceous materials having different Raman R values are contained. and different x-ray parameters.

[2-3-1-3. Materials containing metallic elements and/or metalloid elements that can be alloyed with Li]
(ii) Materials containing metallic elements and/or semi-metallic elements that can be alloyed with Li can be any of the conventionally known ones. A metal or semimetal selected from the group consisting of Sn, Al, As, and Zn is preferred. In addition, when the material containing a metal element and/or metalloid element that can be alloyed with Li contains two or more metals, the material may be an alloy material made of an alloy of these metals.
The compound containing a metal element and/or metalloid element that can be alloyed with Li includes oxides, nitrides, carbides, and the like of metals and/or metalloids. The compound may contain two or more metal elements and/or metalloid elements that can be alloyed with Li. Among these, metal Si (hereinafter also referred to as "Si") or Si-containing inorganic compounds are preferable in terms of increasing the capacity. In this specification, Si or Si-containing inorganic compounds are collectively referred to as Si compounds.
In addition, the compound containing a metal element and/or metalloid element that can be alloyed with Li may already be alloyed with Li at the time of manufacturing the negative electrode described later, and the compound is a Si compound with a high capacity. preferred in terms of conversion.
Examples of Si compounds include SiO _x1 (0≦x1≦2).
Examples of metal compounds alloyed with Li include Li _z1 Si (0<z1≦4.4), Li _2z2 SiO _{2 +z2} (0<z2≦2), and the like. As the Si compound, Si oxide (SiO _x2 , 0<x2≦2) is preferable in that it has a larger theoretical capacity than graphite. Alkali ions can easily move in and out, making it possible to obtain a high capacity.
When the material containing the metal element and/or metalloid element that can be alloyed with Li is particulate, the volume average particle diameter (d ₅₀ ) of the particles is usually 0.01 μm or more and 10 μm from the viewpoint of cycle life. It is below.

[2-3-1-4. A mixture of a material containing a metal element and/or a metalloid element that can be alloyed with Li and natural graphite]
(v) A mixture of a material containing a metal element and/or metalloid element that can be alloyed with Li and graphite particles contains the above (ii) metal element and/or metalloid element that can be alloyed with Li It may be a mixture in which the material and the graphite particles are mixed in a state of independent particles, or particles containing a metal element and / or metalloid element that can be alloyed with Li are on the surface or inside of the graphite particles. It may be a complex that exists in
The content ratio of particles containing a metal element and/or metalloid element that can be alloyed with Li to the total of particles containing a metal element and/or metalloid element that can be alloyed with Li and graphite particles is usually 1 mass. % or more and 99% by mass or less.

[2-3-1-5. Lithium-containing metal composite oxide material]
(iii) The lithium-containing metal composite oxide material is not particularly limited as long as it can occlude and release lithium ions. Specifically, from the viewpoint of high-current-density charge-discharge characteristics, a lithium-containing metal composite oxide material containing titanium is preferable, and a composite oxide of lithium and titanium (hereinafter also referred to as "lithium-titanium composite oxide") is preferred. More preferred is a lithium-titanium composite oxide having a spinel structure, which greatly reduces the output resistance.
Also, lithium and/or titanium in the lithium-titanium composite oxide may be substituted with other metal elements such as at least one element selected from the group consisting of Al, Ga, Cu and Zn.
Li _4/3 Ti _5/3 O ₄ , Li ₁ Ti ₂ O ₄ and Li _4/5 Ti _11/5 O ₄ are preferable as the lithium titanium composite oxide. Li4/ _3Ti4 / _3Al1 / _{3O4 ,} for example, is also preferable as a lithium-titanium composite oxide in which part of lithium and/or titanium is replaced with another element.

[2-3-2. Structure and Manufacturing Method of Negative Electrode]
Any known method may be used to manufacture the negative electrode as long as it does not impair the effects of the present invention. For example, to the negative electrode active material, a binder, a liquid medium such as an aqueous solvent and an organic solvent, and, if necessary, a thickener, a conductive material, a filler, etc. are added to form a slurry, which is applied to the current collector. can be produced by drying and then pressing to form a negative electrode active material layer.

[2-3-2-1. Content of negative electrode active material]
The content of the negative electrode active material in the negative electrode active material layer is usually 80% by mass or more and 99.5% by mass or less.

[2-3-2-2. Electrode density]
The negative electrode active material layer obtained by coating and drying is preferably densified by hand pressing, roller pressing, or the like in order to increase the filling density of the negative electrode active material.
The electrode structure when the negative electrode active material is formed into an electrode is not particularly limited, but the density of the negative electrode active material layer present on the current collector is usually 1 g/cm ³ or more and 2.2 g/cm ³ or less.

[2-3-2-3. Thickener]
Thickeners are commonly used to adjust the viscosity of the slurry. The thickener is not particularly limited, but specific examples include carboxymethylcellulose and salts thereof, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, and the like. These can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.
When a thickener is used, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less.

[2-3-2-4. Binder]
The binder that binds the negative electrode active material is not particularly limited as long as it is stable with respect to the non-aqueous electrolytic solution and the liquid medium used in electrode production.
Specific examples thereof include rubber-like polymers such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber, fluororubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene rubber, polyvinylidene fluoride, polytetrafluoroethylene, Fluorinated polymers such as fluorinated polyvinylidene fluoride and tetrafluoroethylene-ethylene copolymers are included. These can be used individually by 1 type or in combination of 2 or more types by arbitrary ratios.
The content of the binder with respect to the negative electrode active material is usually 0.1% by mass or more and 20% by mass or less.
In particular, when the binder contains a rubber-like polymer represented by SBR as a main component, the content of the binder with respect to the negative electrode active material is usually 0.1% by mass or more and 5% by mass or less. . Moreover, when the binder contains a fluorine-based polymer represented by polyvinylidene fluoride as a main component, the content of the binder with respect to the negative electrode active material is usually 1% by mass or more and 15% by mass or less.

[2-3-2-5. current collector]
As the current collector for holding the negative electrode active material, any known current collector can be used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable in terms of ease of processing and cost.
Examples of the shape of the current collector of the negative electrode include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punched metal, and foamed metal. Among these, a metal foil or a metal thin film is preferred. Incidentally, the metal thin film may be appropriately formed in a mesh shape.
When the shape of the current collector of the negative electrode is plate-like, film-like, or the like, the thickness of the current collector is arbitrary, but is usually 1 μm or more and 1 mm or less.

[2-3-2-6. Thickness of negative electrode plate]
The thickness of the negative electrode (negative plate) is designed according to the positive electrode (positive plate) to be used, and is not particularly limited. , usually 15 μm or more and 300 μm or less.

[2-3-2-7. Surface coating of negative electrode plate]
In addition, the negative electrode plate may have a surface adhered with a substance having a composition different from that of the negative electrode active material (surface adhering substance). Examples of the surface adhering substance include oxides such as aluminum oxide, sulfates such as lithium sulfate, and carbonates such as lithium carbonate.

[2-4. Separator]
A separator is usually interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the separator is usually impregnated with the non-aqueous electrolytic solution.
The material and shape of the separator are not particularly limited, and any known material can be employed as long as the effects of the present invention are not impaired.

[2-5. battery design]
[2-5-1. Electrode group]
The electrode group has a laminate structure in which the positive electrode plate and the negative electrode plate are interposed between the separators, and a structure in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween. Either is fine. The ratio of the volume of the electrode group to the internal volume of the battery (electrode group occupancy) is usually 40% or more and 90% or less.

[2-5-2. Current collection structure]
When the electrode group has the above-described laminated structure, a structure in which the metal core portions of the electrode layers are bundled and welded to a terminal is preferably used. A structure in which a plurality of terminals are provided in an electrode to reduce resistance is also preferably used. When the electrode group has the wound structure described above, the internal resistance can be reduced by providing a plurality of lead structures for each of the positive electrode and the negative electrode and bundling them around the terminal.

[2-5-3. Protective element]
Protective elements include PTC (Positive Temperature Coefficient) elements that increase resistance as heat is generated due to excessive current, thermal fuses, thermistors, and valves that cut off the current flowing through the circuit due to a sudden increase in battery internal pressure or internal temperature during abnormal heat generation. (current cut-off valve) or the like can be used. It is preferable to select the protective element under the condition that it does not operate under normal high-current use, and it is more preferable to design such that abnormal heat generation and thermal runaway do not occur even without the protective element.

[2-5-4. exterior body]
A non-aqueous electrolyte battery is generally configured by housing the non-aqueous electrolyte of the present invention, a negative electrode, a positive electrode, a separator, and the like in an exterior body (exterior case). There is no limitation on the exterior body, and any known exterior body can be adopted as long as the effect of the present invention is not impaired.
The material of the outer case is not particularly limited as long as it is stable with respect to the non-aqueous electrolytic solution used, but from the viewpoint of weight reduction and cost, metals such as iron, aluminum, and aluminum alloys or laminated films are preferably used. be done. In particular, iron is preferable because of its pressure resistance for operating the current cut-off valve.
The exterior case using the above metals has a sealed structure by welding the metals together by laser welding, resistance welding, or ultrasonic welding, or a crimped structure using the above metals via a resin gasket. There are things to do.

[2-5-5. shape]
Moreover, the shape of the exterior case is also arbitrary, and may be cylindrical, rectangular, laminated, coin-shaped, large-sized, or the like.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The compounds used in this example are shown below.
Compound (A): vinyl ethylene sulfite

MA: methyl acetate VC: vinylene carbonate PRES: 1-propene-1,3-sultone

<Example 1, Comparative Examples 1 to 3>
(Preparation of non-aqueous electrolytic solution)
In a dry argon atmosphere, a mixture of ethylene carbonate, dimethyl carbonate, and methyl acetate (MA) as the linear carboxylic acid ester (C) shown in Table 1 (volume ratio 3:4:3) was added with sufficiently dried LiPF. ₆ was dissolved in the non-aqueous electrolytic solution so that the concentration was 1.0 mol / L, and vinyl ethylene sulfite as compound (A) and carbonate compound (B) were added so that the content was as shown in Table 1. A non-aqueous electrolytic solution was prepared by dissolving VC as. Using this non-aqueous electrolyte, a non-aqueous electrolyte secondary battery was produced by the following method. Comparative Example 1 does not contain VC, and Comparative Example 2 does not contain MA. In Comparative Example 3, instead of VC, PRES was dissolved in the non-aqueous electrolytic solution so that its concentration was 1% by mass.

(Preparation of positive electrode)
85 parts by mass of lithium cobalt nickel manganese oxide (Li _1.05 Ni _0.34 Co _0.33 Mn _0.33 O ₂ ) as a positive electrode active material, 10 parts by mass of acetylene black as a conductive material, and polyvinylidene fluoride as a binder 5 parts by mass of (PVdF) were mixed and slurried in N-methyl-2-pyrrolidone. This was uniformly applied to an aluminum foil having a thickness of 15 μm, dried, and roll-pressed to obtain a positive electrode. The density of the positive electrode active material layer in the positive electrode was 2.6 g/cm ³ .

(Preparation of negative electrode)
49 parts by mass of graphite powder as a negative electrode active material, 50 parts by mass of an aqueous dispersion of sodium carboxymethylcellulose (concentration of 1% by mass of sodium carboxymethylcellulose) as a thickener, and an aqueous dispersion of styrene-butadiene rubber as a binder. (Concentration of styrene-butadiene rubber: 49% by mass) was added and mixed with a disperser to form a slurry. The resulting slurry was uniformly applied to a copper foil having a thickness of 10 μm, dried, and roll-pressed to form a negative electrode. The density of the negative electrode active material layer in the negative electrode was 1.35 g/cm ³ .
(Manufacture of non-aqueous electrolyte secondary battery)
The positive electrode, the negative electrode, and the polyolefin separator prepared above were laminated in the order of the negative electrode, the separator, and the positive electrode. The thus-obtained battery element was wrapped with an aluminum laminate film, filled with the non-aqueous electrolyte, and then vacuum-sealed to produce a sheet-like non-aqueous electrolyte secondary battery.

[Evaluation of non-aqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery produced above was evaluated as follows.
(initial charge/discharge)
In a constant temperature bath at 25 ° C., a sheet-shaped non-aqueous electrolyte secondary battery is constant current charged to 3.6 V at a current equivalent to 0.025 C, and then constant current-constant to a voltage of 4.2 V at 0.167 C. Voltage charging (hereinafter also referred to as "CC-CV charging") was performed, and then constant current discharge was performed at 0.167C to 2.5V.
Further, after CC-CV charging at 0.167 C to 4.1 V, the non-aqueous electrolyte secondary battery was stabilized by storing at 60° C. for 12 hours. After that, at 25° C., the battery was discharged at a constant current of 0.167 C to 2.5 V, and then CC-CV charged at 0.167 C to a voltage of 4.2 V to complete the initial charge and discharge.
Here, 1C represents the current value for discharging the standard capacity of the battery in one hour, and 0.025C represents 1/40 of that current value, for example. The same applies hereinafter.

(Initial DCR evaluation test)
The non-aqueous electrolyte secondary battery after the initial charge/discharge was subjected to constant current discharge at 0.167C to 2.5V, and then CC-CV charge to 3.7V at 0.167C. Then, constant current discharge was performed at 0.5C, 1.0C and 1.5C for 10 seconds each, and the voltage at 10 seconds was measured. The internal resistance was obtained from this current-voltage straight line and used as the initial DCR (direct current resistance).

Table 1 shows the evaluation results of the initial DCR, and the non-aqueous electrolyte secondary battery (Comparative Example 1) containing methyl acetate as the chain carboxylic acid ester (C) and containing the compound (A) was set to 100. It is indicated by a relative value (initial DCR change rate). It should be noted that the smaller the value of the initial DCR change rate, the better.

As is clear from Table 1, a non-aqueous electrolyte secondary battery containing a chain carboxylic acid ester as a solvent in the non-aqueous electrolyte and further containing the compound (A) and the carbonate compound (B) in the non-aqueous electrolyte (Example 1) is a non-aqueous electrolyte secondary battery (Comparative Example 1) that does not contain a carbonate compound (B) in a non-aqueous electrolyte and a non-aqueous electrolyte that does not contain a chain carboxylic acid ester (C) in a non-aqueous electrolyte. Compared to the aqueous electrolyte secondary battery (Comparative Example 2) and the non-aqueous electrolyte secondary battery (Comparative Example 3) containing PRES used in the conventional technology instead of the carbonate compound (B) in the non-aqueous electrolyte, The increase in initial DCR is suppressed.

Although the non-aqueous electrolyte solution of the present invention contains a carboxylic acid ester with high reductive reactivity at the negative electrode as a non-aqueous solvent, the internal resistance of the non-aqueous electrolyte battery can be reduced by using it as the electrolyte solution for the non-aqueous electrolyte battery. increase can be suppressed. Therefore, the non-aqueous electrolytic solution of the present invention can be suitably used in all fields such as electronic devices in which non-aqueous electrolytic solution batteries are used.
Moreover, the non-aqueous electrolytic solution of the present invention and the non-aqueous electrolytic solution battery using the same can be used for various known applications. Specific examples of applications include notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, mobile faxes, mobile copiers, mobile printers, mobile audio players, small video cameras, headphone stereos, video movies, and liquid crystals. TVs, handy cleaners, portable CDs, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power sources, motors, automobiles, motorcycles, motorized bicycles, bicycles, lighting equipment, toys, game equipment, Clocks, power tools, strobes, cameras, home backup power sources, office backup power sources, load leveling power sources, natural energy storage power sources, and the like.

Claims (9)

A non-aqueous electrolytic solution characterized by containing a compound (A) represented by formula (I), a cyclic carbonate (B), and a chain carboxylic acid ester (C),
A non-aqueous electrolytic solution in which the cyclic carbonate (B) is one or more selected from cyclic carbonates having a carbon-carbon unsaturated bond and cyclic carbonates having a fluorine atom.

(In formula (I), X ¹ and X ² are each independently an oxygen atom or CH ₂ , R ¹ and R ² are each independently a hydrogen atom, a halogen atom, or a hydrocarbon group, and n is , 1 or 2, provided that either one of R ¹ and R ² is a hydrocarbon group containing at least one carbon-carbon unsaturated bond, and when n is 2, X ¹ and X ² is _CH2 .) The non-aqueous electrolytic solution according to claim 1, wherein the compound (A) is a compound represented by the following formula (II).

(In formula (II), R ¹ and R ² are the same as R ¹ and R ² in formula (I) above.) R ¹ and R ² are each independently one selected from a hydrogen atom, a halogen atom, a vinyl group, and an allyl group, and one of R ¹ and R ² is selected from a vinyl group and an allyl group The non-aqueous electrolyte solution according to claim 1 or 2. The non-aqueous electrolytic solution according to claim 1 or 2, containing 0.01% by mass or more and 10% by mass or less of the compound (A). The non-aqueous electrolytic solution according to claim 1 or 2, wherein the cyclic carbonate (B) is vinylene carbonate and/or fluoroethylene carbonate. The non-aqueous electrolytic solution according to claim 1 or 2, containing 0.001% by mass or more and 10% by mass or less of the cyclic carbonate (B). The non-aqueous electrolytic solution according to claim 1 or 2, wherein the chain carboxylic acid ester (C) is methyl acetate or methyl propionate. The non-aqueous electrolytic solution according to claim 1 or 2, wherein the content of said chain carboxylic acid ester (C) in said non-aqueous solvent is 1% by volume or more and 70% by volume or less. A non-aqueous system comprising a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions, a negative electrode having a negative electrode active material capable of absorbing and releasing metal ions, and the non-aqueous electrolytic solution according to claim 1 or 2. electrolyte battery.