WO2020017318A1

WO2020017318A1 - Nonaqueous electrolyte solution and electricity storage device using same

Info

Publication number: WO2020017318A1
Application number: PCT/JP2019/026284
Authority: WO
Inventors: 良規栗原; 大希木戸; 雄一古藤; 宏行瀬戸口; 藤村　整
Original assignee: 宇部興産株式会社
Priority date: 2018-07-17
Filing date: 2019-07-02
Publication date: 2020-01-23
Also published as: JP7344874B2; JPWO2020017318A1; JP2023099207A

Abstract

The present invention provides: (1) a nonaqueous electrolyte solution in which an electrolyte salt is dissolved in a nonaqueous solvent, wherein the nonaqueous electrolyte solution is characterized by containing a specific zwitterion; and (2) an electricity storage device comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte solution in which an electrolyte salt is dissolved in a nonaqueous solvent, wherein the electricity storage device is characterized in that the nonaqueous electrolyte solution contains a specific zwitterion. This electricity storage device is capable of greatly improving high-temperature charge preservation properties.

Description

Non-aqueous electrolyte and power storage device using the same

The present invention relates to a non-aqueous electrolyte capable of suppressing electrochemical characteristics, particularly a decrease in battery capacity during high-temperature charge storage, and a power storage device using the same.

In recent years, power storage devices, especially lithium batteries, have been widely used as power sources for small electronic devices such as mobile phones and notebook computers, as power sources for electric vehicles and for power storage. In this specification, the term lithium battery is used as a concept including a so-called lithium ion secondary battery.

A lithium battery is mainly composed of a positive electrode and a negative electrode containing a material capable of occluding and releasing lithium ions, a lithium salt, and a non-aqueous electrolytic solution composed of a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), Carbonates such as propylene carbonate (PC) are used.
As a negative electrode of a lithium battery, a lithium metal, a metal compound capable of occluding and releasing lithium ions (a simple metal, a metal oxide, an alloy with lithium, and the like), a carbon material, and the like are known. In particular, among carbon materials, lithium batteries using carbon materials capable of occluding and releasing lithium ions such as coke and graphite (artificial graphite and natural graphite) have been widely put into practical use.
Since carbon materials such as coke and graphite store and release lithium ions and electrons at a very low potential equivalent to lithium metal, many solvents in non-aqueous electrolytes have the potential to undergo reductive decomposition. I have. When the solvent in the non-aqueous electrolyte is reductively decomposed on the negative electrode, deposition of decomposed products on the negative electrode surface and gas generation hinder smooth movement of lithium ions, lowering battery characteristics such as high-temperature storage characteristics. There's a problem.
On the other hand, as the positive electrode of the lithium battery, a composite metal oxide with lithium containing one or more selected from the group consisting of cobalt, manganese, and nickel, which can occlude and release lithium ions, is used. . Here, heavy metals in the positive electrode active material may be eluted into the non-aqueous electrolyte during high temperature charge storage. When the eluted metal is reprecipitated on the negative electrode, problems such as a decrease in battery capacity, an increase in the amount of gas generated due to decomposition of the non-aqueous electrolyte, and an increase in electric resistance occur.

Patent Literature 1 proposes a non-aqueous electrolyte containing an organic solvent, a lithium salt, and an internal salt having a cation and an anion in the molecule, and utilizes a dissolution and deposition reaction of lithium for the negative electrode. It is disclosed that in a lithium battery using an active material, charge / discharge cycle characteristics are improved in a 30-cycle test. However, in the lithium battery to which the non-aqueous electrolyte solution of Patent Document 1 is applied, although there is a description about improving charge / discharge cycle characteristics in a low-temperature cycle test, the effect of improving battery storage characteristics at high temperatures is described. Absent. In addition, among the intramolecular salts having a cation and an anion in the molecule described in Patent Document 1, there are those which are insoluble only in a small amount in an organic solvent in which a lithium salt is dissolved and cannot exert an effect. Have been.
Patent Document 2 proposes a non-aqueous electrolyte containing an organic solvent, a lithium salt, and an internal salt containing anionic SO ₃ or SO ₄ and a cationic triazine in the same molecule. It is disclosed that the high-temperature storage characteristics of the secondary battery and the stability during overcharge are improved.
Patent Literature 3 proposes a non-aqueous electrolyte containing an organic solvent such as ethylene carbonate, a lithium salt, and a zwitterionic compound containing a nitrogen atom or a phosphorus atom, and has excellent electrochemical stability. It has been disclosed.

JP-A-2003-346897 US Patent Application Publication No. 2017/0125847 International Publication No. WO 2016/027788

An object of the present invention is to provide a non-aqueous electrolyte capable of significantly improving the high-temperature charge storage characteristics of an electricity storage device, and an electricity storage device using the same.
The present invention further provides a non-aqueous electrolyte capable of improving the high-temperature charge storage characteristics of the power storage device and, in addition, significantly suppressing generated gas during storage, and a power storage device using the same. The purpose is to do.

The present inventors have repeated studies to solve the above-mentioned problems, and a non-aqueous electrolyte containing zwitterions has an effect of suppressing a decrease in battery capacity during high-temperature charge storage and an effect of suppressing generated gas. As a result of further intensive studies, they have found that zwitterions improve solubility in organic solvents and further improve battery characteristics, and have completed the present invention.
Furthermore, it has been found that a zwitterion in which the cationic group contains a phosphorus atom or a nitrogen atom having no heterocycloalkenyl group and the anionic group is —SO ₄ ^— particularly improves battery performance. Was completed.
That is, the present invention provides the following (1) and (2).

(1) A non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, wherein the non-aqueous electrolyte solution contains a zwitterion represented by the following general formula (I).

(In the formula (I), Q ⁺ is a cationic group represented by the following formula (II) or (III).
L ¹ is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or 1 to 4 carbon atoms. Represents an alkyleneoxy group.
A ^- anionic group represented by is a sulfonate or carboxylato group. )

(In the formula (II), R ¹ to R ³ each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, It represents a fluorinated alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 3 to 15 carbon atoms, or a fluorinated alkynyl group having 3 to 15 carbon atoms.
In the formula (III), R ⁴ to R ⁶ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site with ^{L 1.} )

(2) A power storage device including a positive electrode, a negative electrode, and a non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent, wherein the non-aqueous electrolyte is the non-aqueous electrolyte according to (1). An electricity storage device characterized by the above-mentioned.

In the present specification, the term “zwitterion” means an inner salt having a positive charge (cationic group) and a negative charge (anionic group) in one molecule.

Advantageous Effects of Invention According to the present invention, it is possible to provide a non-aqueous electrolyte that can significantly suppress a decrease in battery capacity during high-temperature charge storage of an electricity storage device, and an electricity storage device such as a lithium battery using the same.
Further, according to the present invention, there is provided a non-aqueous electrolyte capable of suppressing a decrease in battery capacity during high-temperature charge storage of a power storage device and a gas generated during high-temperature charge storage, and a power storage device such as a lithium battery using the same. be able to.

<Non-aqueous electrolyte>
The non-aqueous electrolyte of the present invention is a non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent, wherein at least one zwitterion represented by the general formula (I) is contained in the non-aqueous electrolyte. It is characterized by containing.

The reason why the non-aqueous electrolyte of the present invention improves the high-temperature charge storage characteristics of the power storage device is not necessarily clear, but is considered as follows.
One of the causes of a decrease in battery capacity when an electricity storage device is stored at high temperatures is that metals such as cobalt, nickel, and manganese elute from the positive electrode active material, are reduced on the negative electrode, and are unstable on the SEI (Solid Electrolyte). Interphase) forming a coating. The zwitterion of the general formula (I) of the present invention specifically coordinates to the eluted metal. It is considered that a metal to which a zwitterion is coordinated forms a stable SEI film even when reduced on the negative electrode, and improves battery characteristics. In addition, since the cationic group in the general formula (I) is chemically more stable than a heterocycloalkenyl group such as triazine, the effect of a zwitterion is improved, and the cationic group is an anionic group. The —SO ₄ ^— group exhibits an effective electrode resistance reducing action. Therefore, it is considered that the zwitterion in the combination of the anionic group and the cationic group of the formula (I) promotes the improvement of the battery characteristics.

(Zwitterion)
The zwitterion according to the present invention is represented by the following general formula (I).

In the formula (I), Q ⁺ is a cationic group represented by the following formula (II) or (III).
L ¹ is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or 1 to 4 carbon atoms. Represents an alkyleneoxy group. Among them, L ¹ is preferably an alkylene group having 1 to 3 carbon atoms, an alkenylene group having 2 to 3 carbon atoms, or an alkyleneoxy group having 1 to 4 carbon atoms.
A ^- anionic group represented by the sulfonate group is ^- ^- (group -COO) (-SO ₃ group) or a carboxylato group.

In the formula (II), R ¹ to R ³ each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, And represents a fluorinated alkenyl group having 3 to 15 carbon atoms, an alkynyl group having 3 to 15 carbon atoms, or a fluorinated alkynyl group having 3 to 15 carbon atoms. Among these, R ¹ to R ³ each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, or Up to 15 alkynyl groups are preferred.
In the formula (III), R ⁴ to R ⁶ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group. Among them, R ⁴ to R ⁶ are each independently preferably an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site with ^{L 1.} That is, L ¹ is bonded to a nitrogen atom or a phosphorus atom of Q ⁺ .

In the present invention, the zwitterion is preferably at least one selected from a compound represented by the following general formula (IV) and a compound represented by the following general formula (VII).

In the formula (IV), Q ⁺ is a cationic group represented by the following formula (V) or (VI).
L ² represents a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or an alkyleneoxy group having 1 to 4 carbon atoms.

In the formula (V), R ⁷ to R ⁹ each independently represent an alkyl group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, A fluorinated alkynyl group having 3 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, or a fluorinated alkynyl group having 3 to 5 carbon atoms.
In the formula (VI), R ¹⁰ to R ¹² each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site of the ^{L 2.} That is, L ² is bonded to a nitrogen atom or a phosphorus atom of Q ⁺ .

In the formula (VII), L ³ represents an alkylene group having 1 to 5 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms, more preferably an alkylene group having 1 to 2 carbon atoms, and still more preferably a methylene group.
R ¹³ to R ¹⁵ each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, or a fluorinated alkenyl having 2 to 15 carbon atoms A alkynyl group having 3 to 15 carbon atoms or a fluorinated alkynyl group having 3 to 15 carbon atoms. Among them, R ¹³ to R ¹⁵ are preferably each independently an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms.
However, at least one of R ¹³ to R ¹⁵ is an alkyl group having 3 to 15 carbon atoms.

<Zwitterion represented by general formula (IV)>
The zwitterion represented by the general formula (IV) is more preferably a compound represented by the following general formula (VIII).

In the formula (VIII), Q ⁺ is a cationic group represented by the following formula (IX) or (X).
L ⁴ represents an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, or a fluorinated alkenylene group having 2 to 5 carbon atoms. Among them, L ⁴ is preferably an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, and an alkylene group having 1 to 3 carbon atoms, Alternatively, an alkenylene group having 2 to 3 carbon atoms is more preferable, and an alkylene group having 2 to 3 carbon atoms is further preferable.

In the formula (IX), R ¹⁶ to R ¹⁸ each independently represent an alkyl group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, A fluorinated alkynyl group having 3 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, or a fluorinated alkynyl group having 3 to 5 carbon atoms. Among them, R ¹⁶ to R ¹⁸ each independently represent an alkyl group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or A fluorinated alkenyl group having 5 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms and an alkenyl group having 2 to 5 carbon atoms are more preferable, and an alkyl group having 1 to 3 carbon atoms and an alkenyl group having 2 to 3 carbon atoms are preferable. More preferred.

In the formula (X), R ¹⁹ to R ²¹ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group. Among them, R ¹⁹ to R ²¹ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, An alkenyl group, dimethylamino group or diethylamino group having 5 carbon atoms is preferable, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, dimethylamino group or diethylamino group is more preferable. An alkyl group, an alkenyl group having 2 to 3 carbon atoms, a dimethylamino group, or a diethylamino group is more preferred, and an alkyl group having 1 to 3 carbon atoms is most preferred.
* Indicates a binding site of the ^{L 4.} That is, L ⁴ is bonded to a nitrogen atom or a phosphorus atom of Q ⁺ .

In the present invention, the zwitterion represented by the general formula (IV) or (VIII) is selected from a compound represented by the following general formula (XI) and a compound represented by the following general formula (XII) More preferably, it is at least one.

L ⁵ in the formula (XI) and L ⁶ in the formula (XII) represent an alkylene group having 2 or 3 carbon atoms.
In the formula (XI), R ¹⁶ to R ¹⁸ each independently represent an alkyl group having 1 to 3 carbon atoms.
In the formula (XII), R ¹⁹ to R ²¹ each independently represent an alkyl group having 1 to 3 carbon atoms or a dimethylamino group. )

双 Specific examples of the zwitterion represented by the general formula (IV), (VIII), (XI) or (XII) include the following compounds.

Among the above compounds, 2- (trimethylammonio) ethyl sulfate (structural formula 1), 2- (triethylammonio) ethyl sulfate (structural formula 4), and 2- (tripropylammonio) ethyl sulfate (structural formula) 5), 3- (trimethylammonio) propyl sulfate (structural formula 7), 3- (triethylammonio) propyl sulfate (structural formula 10), 3- (tripropylammonio) propyl sulfate (structural formula 11), 2 From the group consisting of-(tributylphosphonio) ethyl sulfate (structural formula 15), 2- (trisdimethylaminophosphonio) ethyl sulfate (structural formula 17), and 3- (tributylphosphonio) propyl sulfate (structural formula 20) More than one kind to be chosen.

Among the above compounds, more preferably, 2- (trimethylammonio) ethyl sulfate (structural formula 1), 2- (triethylammonio) ethyl sulfate (structural formula 4), 2- (tripropylammonio) ethyl sulfate (structure At least one selected from the group consisting of formula 5), 2- (tributylphosphonio) ethyl sulfate (structural formula 15), and 2- (trisdimethylaminophosphonio) ethyl sulfate (structural formula 17), and more preferably From the group consisting of 2- (trimethylammonio) ethyl sulfate (structural formula 1), 2- (triethylammonio) ethyl sulfate (structural formula 4), and 2- (tripropylammonio) ethyl sulfate (structural formula 5) More than one kind to be chosen.

<Zwitterion represented by general formula (VII)>
The zwitterion represented by the general formula (VII) is more preferably a compound represented by the following general formula (VII-I).

In the formula (VII-1), L ³ is a methylene group, R ¹³ to R ¹⁵ are each independently an alkyl group having 1 to 15 carbon atoms, and at least one of R ¹³ to R ¹⁵ has 3 carbon atoms. ~ 15 alkyl groups.

双 Specific examples of the zwitterion represented by formula (VII) or (VII-1) include the following compounds.

Among the above compounds, preferably, 2-butyldimethyl (carboxylatomethyl) ammonium (structural formula 1), 2-butyldimethyl (carboxylatoethyl) ammonium (structural formula 2), 2-butyldimethyl (carboxylatopropyl) ammonium ( Structural formula 3) 2-hexyldimethyl (carboxylatomethyl) ammonium (structural formula 7), 2-hexyldimethyl (carboxylatoethyl) ammonium (structural formula 8), 2-hexyldimethyl (carboxylatopropyl) ammonium (structural formula 9) 2-octyldimethyl (carboxylatomethyl) ammonium (structural formula 10), 2-octyldimethyl (carboxylatoethyl) ammonium (structural formula 11), 2-octyldimethyl (carboxylatopropyl) ammonium (structural formula 12) , 2-decyldi Methyl (carboxylatomethyl) ammonium (structural formula 13), 2-decyldimethyl (carboxylatoethyl) ammonium (structural formula 14), 2-decyldimethyl (carboxylatopropyl) ammonium (structural formula 15), 2-dodecyldimethyl ( At least one selected from the group consisting of carboxylatomethyl) ammonium (structure 16), 2-dodecyldimethyl (carboxylatoethyl) ammonium (structure 17) and 2-dodecyldimethyl (carboxylatopropyl) ammonium (structure 18) It is.

Among the above compounds, more preferably, 2-butyldimethyl (carboxylatomethyl) ammonium (structural formula 1), 2-hexyldimethyl (carboxylatomethyl) ammonium (structural formula 7), 2-octyldimethyl (carboxylatomethyl) ammonium (Structural formula 10) It is at least one member selected from the group consisting of 2-decyldimethyl (carboxylatomethyl) ammonium (structural formula 13) and 2-dodecyldimethyl (carboxylatomethyl) ammonium (structural formula 16).

Further, triethyl (sulfopropyl) ammonium and (tributylphosphonio) propylsulfonate can be used as the zwitterion. In this case, a lithium composite metal oxide containing manganese is used as the positive electrode active material, As the active material, it is preferable to use at least one selected from a carbon material capable of inserting and extracting lithium and a titanium composite metal oxide, and a manganese-containing spinel-type lithium composite containing manganese as the positive electrode active material. It is more preferable to use a metal oxide, particularly spinel-type lithium manganate (LiMn ₂ O ₄ ), and to use a titanium composite metal oxide, particularly Li ₄ Ti ₅ O ₁₂ as a negative electrode active material.

On the other hand, when the compound represented by the general formula (IV), (VIII), (XI) or (XII) is used, as described later, the lithium composite metal oxide containing manganese is used as the positive electrode active material. Is preferable, a manganese lithium composite metal oxide having a spinel structure is more preferable, and a spinel lithium manganate is further preferable. Further, as the negative electrode active material, it is preferable to use at least one selected from a carbon material capable of inserting and extracting lithium and a titanium composite metal oxide.
In addition, when the compound represented by the general formula (VII) or (VII-1) is used, as described later, a lithium composite metal oxide containing manganese is preferable as the positive electrode active material, and a spinel type structure is used. Is more preferable, and spinel-type lithium manganate is more preferable. As the negative electrode active material, it is preferable to use a carbon material capable of inserting and extracting lithium.

In the non-aqueous electrolyte of the present invention, each of the compounds represented by the general formulas (I), (IV), (VII), (VII-1), (VIII), (XI) or (XII) is contained. The amount is preferably 0.01% by mass or more and a saturated amount or less in the non-aqueous electrolyte in order to sufficiently exert the effect. In consideration of industrial production, the lower limit is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. Further, the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 5% by mass or less, and most preferably 2% by mass or less.
Further, the total content of the compounds represented by the above general formulas is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.03% by mass or more and 8% by mass or less, and further preferably 0.05% by mass or less. It is from 5% by mass to 5% by mass, most preferably from 0.1% by mass to 2% by mass.

In the non-aqueous electrolyte solution of the present invention, the compound represented by the general formula (I) is combined with a non-aqueous solvent, an electrolyte salt and other additives described below to reduce the battery capacity during high-temperature charge storage. And a unique effect that the effect of suppressing gas generation during high-temperature charge storage is synergistically improved.

(Non-aqueous solvent)
First, in this specification, the term "solvent" means a substance for dissolving a solute.
As the non-aqueous solvent used in the non-aqueous electrolyte of the present invention, one or more selected from cyclic carbonates, chain esters, lactones, ethers, and amides are preferred. Since the electrochemical properties at high temperatures are synergistically improved, a chain ester is preferably contained, a chain carbonate is more preferably contained, and both a cyclic carbonate and a chain ester are more preferably contained. .

In addition, the term "chain ester" is used as a concept including a chain carbonate and a chain carboxylic acid ester.
Further, "chain carbonate" is defined as a linear alkyl carbonate compound.

(Cyclic carbonate)
As the cyclic carbonate, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolan-2-one (FEC), trans or Cis-4,5-difluoro-1,3-dioxolan-2-one (both are collectively referred to as “DFEC”), vinylene carbonate (VC), vinylethylene carbonate (VEC), and 4-ethynyl-1 , 3-dioxolan-2-one (EEC), preferably one or more selected from the group consisting of ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolan-2-one, vinylene Carbonate and 4-ethynyl-1,3-dioxolan-2-one (EE ) One or more members selected from the group consisting of is more preferable.

The content of the cyclic carbonate is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more with respect to the total amount of the nonaqueous electrolyte, and the upper limit thereof is preferably 90 mass% or less, more preferably 70 mass% or less, still more preferably 50 mass% or less, and still more preferably 40 mass% or less. When it is in the range, the high-temperature charge storage characteristics can be further improved without impairing the Li ion permeability. Is improved, and gas generation can be suppressed.

When at least one of a carbon-carbon double bond or a carbon-carbon triple bond unsaturated bond or a cyclic carbonate having a fluorine atom is used, high-temperature charge storage characteristics can be further improved, and gas generation can be further suppressed. It is more preferable to include both a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond and a cyclic carbonate having a fluorine atom. As a cyclic carbonate having an unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond, VC, VEC or EEC is more preferable, and as a cyclic carbonate having a fluorine atom, FEC or DFEC is more preferable.

The content of the cyclic carbonate having a carbon-carbon double bond or a carbon-carbon triple bond is preferably 0.05% by mass or more, more preferably 0.1% by mass, based on the total amount of the nonaqueous electrolyte. % Or more, more preferably 0.5% by mass or more, and the upper limit thereof is preferably 8% by mass or less, more preferably 5% by mass or less, and still more preferably 3% by mass or less. This is preferable because the high-temperature charge storage characteristics can be further improved without impairing the Li ion permeability, and gas generation can be suppressed.

The content of the cyclic carbonate having a fluorine atom is preferably 0.05% by mass or more, more preferably 1% by mass or more, and still more preferably 3% by mass or more based on the total amount of the nonaqueous electrolyte. Is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and still more preferably 15% by mass or less. Within this range, the Li ion permeability is further reduced without impairing it. This is preferable because the high-temperature charge storage characteristics can be improved and gas generation can be suppressed.

One of these solvents may be used, and when two or more of them are used in combination, the high-temperature charge storage characteristics can be improved, and gas generation can be suppressed. It is more preferred to use. Preferred combinations of these cyclic carbonates include combinations of EC and PC, combinations of EC and VC, combinations of PC and VC, combinations of VC and FEC, combinations of EC and FEC, combinations of PC and FEC, and combinations of FEC and DFEC. Combination, EC and DFEC combination, PC and DFEC combination, VC and DFEC combination, VEC and DFEC combination, VC and EEC combination, EC and EEC combination, EC and PC and VC combination, EC and PC And FEC combination, EC and VC and FEC combination, EC and VC and VEC combination, EC and VC and EEC combination, EC and EEC and FEC combination, PC and VC and FEC combination, EC and VC and DFEC Combination, combination of PC, VC, and DFEC, combination of EC, PC, VC, and FEC, and combination of EC, PC, VC, and DFEC So it is preferable. Among the above combinations, a combination of EC and VC, a combination of EC and FEC, a combination of PC and FEC, a combination of EC and PC and VC, a combination of EC and PC and FEC, a combination of EC and VC and FEC, and a combination of EC and FEC One or more selected from the group consisting of a combination of VC and EEC, a combination of EC and EEC and FEC, a combination of PC and VC and FEC, and a combination of EC, PC, VC and FEC are more preferable.

(Chain ester)
As the chain ester, one or two or more asymmetric chain carbonates selected from methyl ethyl carbonate (MEC), methyl propyl carbonate, methyl butyl carbonate, and ethyl propyl carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC) ), Dipropyl carbonate, and one or more symmetrical linear carbonates selected from the group consisting of dibutyl carbonate, pivalic acid esters such as methyl pivalate, ethyl pivalate and propyl pivalate, methyl propionate, and propionic acid One or more linear carboxylic esters selected from the group consisting of ethyl, propyl propionate, methyl acetate and ethyl acetate are preferred.

Among the above-mentioned chain esters, high conductivity and low risk of deterioration of high-temperature charge storage characteristics due to decomposition of the solvent are low, so that methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), A chain ester having a methyl group selected from the group consisting of methyl propyl carbonate, methyl butyl carbonate, methyl propionate, methyl acetate, and ethyl acetate is preferable, and a chain carbonate having a methyl group is particularly preferable.

鎖 The content of the chain ester in the non-aqueous solvent used in the non-aqueous electrolyte of the present invention is not particularly limited, but is preferably used in the range of 5 to 90% by mass based on the total amount of the non-aqueous electrolyte. When the content is 5% by mass or more, the viscosity of the non-aqueous electrolyte does not become too high, more preferably 10% by mass or more, further preferably 30% by mass or more, and further preferably 50% by mass or more. It is. When the content is 90% by mass or less, the electric conductivity of the non-aqueous electrolyte is reduced and the high-temperature charge storage characteristics are less likely to be reduced.

The ratio of the cyclic carbonate to the chain ester is preferably from 10:90 to 50:50, and more preferably from 30:70 to 40:60, from the viewpoint of improving the electrochemical properties at a high temperature. Is more preferred.

(Other non-aqueous solvents)
In the non-aqueous electrolyte of the present invention, other non-aqueous solvents other than those described above can be used.
Other non-aqueous solvents include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran and 1,4-dioxane, and chains such as 1,2-dimethoxyethane, 1,2-diethoxyethane and 1,2-dibutoxyethane. One or more selected from the group consisting of ethers, amides such as dimethylformamide, sulfones such as sulfolane, and lactones such as γ-butyrolactone (GBL), γ-valerolactone, and α-angelicalactone are preferably exemplified. Can be

The above-mentioned other non-aqueous solvents are usually mixed and used to achieve appropriate physical properties. The combination is preferably, for example, a combination of a cyclic carbonate, a chain ester, and a lactone, or a combination of a cyclic carbonate, a chain ester, and an ether, and more preferably a combination of a cyclic carbonate, a chain ester, and a lactone. And lactone, it is more preferable to use γ-butyrolactone (GBL).

The content of the other non-aqueous solvent is usually preferably 1% by mass or more, more preferably 2% by mass or more, and usually 40% by mass or less, more preferably 30% by mass, based on the total amount of the non-aqueous electrolyte. % By mass or less, more preferably 20% by mass or less. When the concentration is within the above range, the electric conductivity is less likely to be reduced, and the high-temperature charge storage characteristics are less likely to be deteriorated due to the decomposition of the solvent.

(Other additives)
For the purpose of further improving high-temperature charge storage characteristics and suppressing gas generation, it is preferable to further add other additives to the non-aqueous electrolyte.
Specific examples of other additives include the following compounds (A) to (J).

(A) One or more nitriles selected from acetonitrile, propionitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronitrile, suberonitrile, and sebaconitrile.

(B) an aromatic compound having a branched alkyl group such as cyclohexylbenzene, tert-butylbenzene, tert-amylbenzene, or 1-fluoro-4-tert-butylbenzene, biphenyl, terphenyl (o-, m- , P-form), an aromatic compound such as fluorobenzene, methylphenyl carbonate, ethylphenyl carbonate, or diphenyl carbonate.

(C) selected from methyl isocyanate, ethyl isocyanate, butyl isocyanate, phenyl isocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 1,4-phenylene diisocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate One or more isocyanate compounds.

(D) 2-propynyl methyl carbonate, 2-propynyl acetate, 2-propynyl formate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, 2- (methanesulfonyloxy) propionic acid 2- One or more triple bond-containing compounds selected from propynyl, di (2-propynyl) oxalate, 2-butyne-1,4-diyldimethanesulfonate, and 2-butyne-1,4-diyldiformate.

(E) 1,3-propane sultone, 1,3-butane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-propene sultone, 2,2-dioxide-1,2-oxathiolan-4-yl Sulfones such as acetate, cyclic sulfites such as ethylene sulfate, cyclic sulfates such as ethylene sulfate, butanes such as butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate, and methylenemethanedisulfonate Acid ester and one or more S 種 O group-containing compounds selected from vinylsulfone compounds such as divinylsulfone, 1,2-bis (vinylsulfonyl) ethane and bis (2-vinylsulfonylethyl) ether.

種類 (F) The type of the cyclic acetal compound is not particularly limited as long as it has a “acetal group” in the molecule. Specific examples thereof include cyclic acetal compounds such as 1,3-dioxolan, 1,3-dioxane, and 1,3,5-trioxane.

(G) trimethyl phosphate, tributyl phosphate, trioctyl phosphate, tris (2,2,2-trifluoroethyl) phosphate, ethyl {2- (diethoxyphosphoryl) acetate, and 2-propynyl} 2- (diethoxyphosphoryl) ) One or more phosphorus-containing compounds selected from acetate.

The type of (H) carboxylic anhydride is not particularly limited as long as it is a compound having a “C (＝ O) —OC (＝ O) group” in the molecule. Specific examples thereof include chain carboxylic anhydrides such as acetic anhydride and propionic anhydride, succinic anhydride, maleic anhydride, 3-allyl succinic anhydride, glutaric anhydride, itaconic anhydride, and 3-sulfo-anhydride. Cyclic acid anhydrides such as propionic anhydride;

種類 The type of the (J) phosphazene compound is not particularly limited as long as it has a “N = PN group” in the molecule. Specific examples thereof include cyclic phosphazene compounds such as methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, and ethoxyheptafluorocyclotetraphosphazene.

中でも Among the above, it is preferable to include at least one selected from the group consisting of (A) nitrile, (B) aromatic compound, and (C) isocyanate compound, because the electrochemical properties at higher temperatures are further improved.

(A) Among the nitriles, one or more selected from the group consisting of succinonitrile, glutaronitrile, adiponitrile, and pimeronitrile are more preferable.

(B) Among the aromatic compounds, one selected from the group consisting of biphenyl, terphenyl (o-, m-, p-form), fluorobenzene, cyclohexylbenzene, tert-butylbenzene, and tert-amylbenzene Alternatively, two or more are more preferable, and one or two or more selected from the group consisting of biphenyl, o-terphenyl, fluorobenzene, cyclohexylbenzene, and tert-amylbenzene is further preferable.

Among the (C) isocyanate compounds, one or more selected from the group consisting of hexamethylene diisocyanate, octamethylene diisocyanate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate are more preferable.

含有 The content of the compounds (A) to (C) is preferably 0.01 to 7% by mass based on the total amount of the nonaqueous electrolyte. In this range, the film is sufficiently formed without being too thick, the high-temperature charge storage characteristics can be improved, and gas generation can be suppressed. The content is more preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and the upper limit is more preferably 5% by mass or less based on the total amount of the nonaqueous electrolyte. And more preferably 3% by mass or less.

(D) a compound having a triple bond, (E) a compound having a cyclic or chain S ＝ O group selected from the group consisting of sultone, cyclic sulfite, sulfonic acid ester and vinyl sulfone, (F) a cyclic acetal compound, It is preferable to include (G) a phosphorus-containing compound, (H) a cyclic acid anhydride, and (J) a cyclic phosphazene compound since the high-temperature charge storage characteristics can be improved and gas generation can be suppressed.

(D) Examples of the triple bond-containing compound include 2-propynyl methyl carbonate, 2-propynyl methacrylate, 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, di (2-propynyl) oxalate, and 2-butyne-1 One or more members selected from the group consisting of 2,4-diyl} dimethanesulfonate are preferred, and 2-propynyl methanesulfonate, 2-propynyl vinylsulfonate, di (2-propynyl) oxalate, and 2-butyne-1 One or more selected from the group consisting of 2,4-diyldimethanesulfonate is more preferred.

(E) a cyclic or chain-like S ＝ O group-containing compound selected from the group consisting of sultone, cyclic sulfite, cyclic sulfate, sulfonic acid ester, and vinyl sulfone (provided that a triple bond-containing compound and any of the above general formulas) Is not included).

Examples of the cyclic S ＝ O group-containing compound include 1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone, 2,4-butane sultone, 1,3-propene sultone and 2,2-dioxide- One or more selected from the group consisting of 1,2-oxathiolan-4-yl} acetate, methylene} methanedisulfonate, ethylene sulfite, and ethylene sulfate are preferred.

Examples of the chain-like S 基 O group-containing compound include butane-2,3-diyldimethanesulfonate, butane-1,4-diyldimethanesulfonate, dimethylmethanedisulfonate, pentafluorophenylmethanemethanesulfonate, divinylsulfone, And at least one member selected from the group consisting of and bis (2-vinylsulfonylethyl) ether.

Among the cyclic or chain S 又は O group-containing compounds, 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone, 2,2-dioxide-1,2-oxathiolan-4-yl} acetate , Ethylene sulfate, pentafluorophenyl methanesulfonate, and divinyl sulfone.

(F) The cyclic acetal compound is preferably at least one selected from 1,3-dioxolane and 1,3-dioxane, and more preferably 1,3-dioxane.

(G) As the phosphorus-containing compound, one or more selected from ethyl {2- (diethoxyphosphoryl) acetate and 2-propynyl} 2- (diethoxyphosphoryl) acetate is preferable, and 2-propynyl} 2- (diethoxyphosphoryl) Acetate is more preferred.

(H) The cyclic acid anhydride is preferably at least one selected from succinic anhydride, maleic anhydride, and 3-allyl succinic anhydride, and at least one selected from succinic anhydride and 3-allyl succinic anhydride. Is more preferred.

(J) As the cyclic phosphazene compound, one or more cyclic phosphazene compounds selected from methoxypentafluorocyclotriphosphazene, ethoxypentafluorocyclotriphosphazene, and phenoxypentafluorocyclotriphosphazene are preferable, and methoxypentafluorocyclotriphosphazene and One or more selected from ethoxypentafluorocyclotriphosphazene is more preferred.

含有 The content of each of the compounds (D) to (J) is preferably 0.001 to 5% by mass based on the total amount of the nonaqueous electrolyte. In this range, the film is sufficiently formed without being too thick, and the high-temperature charge storage characteristics can be further improved, and gas generation can be suppressed. The content is more preferably 0.01% by mass or more, more preferably 0.1% by mass or more based on the total amount of the nonaqueous electrolyte, and the upper limit is 3% by mass based on the total amount of the nonaqueous electrolyte. %, More preferably 2% by mass or less.

Further, for the purpose of further improving the electrochemical properties at a higher temperature, a lithium salt (I) having an oxalic acid structure, a lithium salt (II) having a phosphoric acid structure, and an SＯO group are further added to the nonaqueous electrolyte. It preferably contains at least one kind of lithium salt selected from lithium salts (III).
Specific examples of the lithium salt include lithium bis (oxalato) borate [LiBOB], lithium difluoro (oxalato) borate [LiDFOB], lithium tetrafluoro (oxalato) phosphate [LiTFOP], and lithium difluorobis (oxalato) phosphate [LiDFOP]. A lithium salt (I) having at least one oxalic acid structure selected from the group consisting of: a lithium salt (II) having a phosphoric acid structure such as LiPO ₂ F ₂ and Li ₂ PO ₃ F; and lithium trifluoro (( (Methanesulfonyl) oxy) borate [LiTFMSB], lithium pentafluoro ((methanesulfonyl) oxy) phosphate [LiPFMSP], lithium methyl sulfate [LMS], lithium ethyl sulfate [LES], Lithium salt (III) having at least one S ＝ O group selected from the group consisting of lithium 2,2,2-trifluoroethyl sulfate [LFES] and FSO ₃ Li is preferable, and LiBOB, LiDFOB, It is more preferable to include a lithium salt selected from the group consisting of LiTFOP, LiDFOP, LiPO ₂ F ₂ , LiTFMSB, LMS, LES, LFES, and FSO ₃ Li.

割合 The proportion of each of the lithium salts in the nonaqueous electrolyte is preferably 0.01% by mass or more and 8% by mass or less based on the total amount of the nonaqueous electrolyte. Within this range, the high-temperature charge storage characteristics can be further improved, and gas generation can be suppressed. It is preferably at least 0.1% by mass, more preferably at least 0.3% by mass, even more preferably at least 0.4% by mass, based on the total amount of the nonaqueous electrolyte. The upper limit is preferably 6% by mass or less, more preferably 3% by mass or less, based on the total amount of the non-aqueous electrolyte.

(Electrolyte salt)
As the electrolyte salt used in the present invention, at least one lithium salt selected from inorganic lithium salts, lithium salts containing an alkyl fluoride group, lithium imide salts having a fluorine atom, and lithium salts having an oxalic acid structure Are preferred.
Examples of the inorganic lithium salt include LiPF ₆ , LiBF ₄ , and LiClO ₄ .
Examples of the lithium salt containing a fluorinated alkyl group include LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₃ (C ₂ F ₅ ) ₃ , and LiPF ₃ (CF ₃ ). _And lithium salts containing a linear alkyl fluoride group, such as ₃ , LiPF ₃ (iso-C ₃ F ₇ ) ₃ and LiPF ₅ (iso-C ₃ F ₇ ).
Examples of the lithium imide salt having a fluorine atom include chains having a fluorine atom such as LiN (SO ₂ F) ₂ [LiFSI], LiN (SO ₂ CF ₃ ) ₂ [LiTFSI], and LiN (SO ₂ C ₂ F ₅ ) _2. Lithium imide salt, and a lithium imide salt having a cyclic fluorinated alkylene chain such as (CF ₂ ) ₂ (SO ₂ ) ₂ NLi and (CF ₂ ) ₃ (SO ₂ ) ₂ NLi.
As the lithium salt having an oxalic acid structure, at least one selected from the group consisting of LiBOB, LiDFOB, LiTFOP, and LiDFOP is preferable, and lithium bis (oxalato) borate [LiBOB] is more preferable.
The above lithium salts can be used alone or in combination of two or more.

Among these, one or more inorganic lithium salts selected from LiPF ₆ , LiBF _{4 and the} like, LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , and LiN (SO ₂ F ₂ ) Lithium imide salt having one or more fluorine atoms selected from [LiFSI] is preferable, and at least LiPF ₆ is preferably used.
Further, a preferable combination of these electrolyte salts includes LiPF ₆ , and further includes at least one lithium selected from LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ F) ₂ [LiFSI]. Preferably, the salt is contained in the non-aqueous electrolyte, and more preferably, both LiPF ₆ and LiFSI are used in combination.

The concentration and total concentration of each of the electrolyte salts are usually preferably 4% by mass or more, more preferably 9% by mass or more, and still more preferably 13% by mass or more, based on the total amount of the nonaqueous electrolyte. The upper limit is preferably 28% by mass or less, more preferably 23% by mass or less, even more preferably 20% by mass or less based on the total amount of the nonaqueous electrolyte.
When the respective concentrations and the total concentration of lithium salts other than LiPF _{6 in the} total amount of the nonaqueous electrolyte are 0.01% by mass or more, the high-temperature charge storage characteristics are improved, and the effect of suppressing gas generation is also increased. It is preferable that the content is 15% by mass or less, preferably 10% by mass or less based on the total amount of the non-aqueous electrolyte, because there is little fear that the high-temperature charge storage characteristics are reduced. Lithium salts other than LiPF ₆ are preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.46% by mass or more, and most preferably 0.1% by mass or more, based on the total amount of the nonaqueous electrolyte. It is at least 6% by mass, and the upper limit is preferably at most 13% by mass, more preferably at most 11% by mass, still more preferably at most 9% by mass, most preferably at most 6% by mass.

(Production of non-aqueous electrolyte)
The non-aqueous electrolyte solution of the present invention is obtained by, for example, mixing the above-mentioned non-aqueous solvent, and adding the compound represented by the general formula (I) to the electrolyte salt and the non-aqueous electrolyte solution. Obtainable.
At this time, it is preferable that the compound added to the non-aqueous solvent and the non-aqueous electrolyte used is one which has been purified in advance and has as few impurities as possible, as long as the productivity is not significantly reduced.

非 The non-aqueous electrolyte of the present invention can be used for the following first to fourth power storage devices. As the non-aqueous electrolyte, not only a liquid electrolyte but also a gelled electrolyte can be used. Further, the non-aqueous electrolyte of the present invention can be used for solid polymer electrolytes. Above all, it is preferable to use it for a first power storage device using a lithium salt as an electrolyte salt (that is, for a lithium battery) or for a fourth power storage device (that is, for a lithium ion capacitor), and to use it for a lithium battery. More preferably, it is most suitable to use for a lithium secondary battery.

<Power storage device>
The power storage device of the present invention is a power storage device including a positive electrode, a negative electrode, and a non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent, wherein the non-aqueous electrolyte is represented by the general formula (I). Characterized by containing a zwitterion.

[First power storage device (lithium battery)]
In this specification, a lithium battery is a general term for a lithium primary battery and a lithium secondary battery. Further, in this specification, the term lithium secondary battery is used as a concept including a so-called lithium ion secondary battery.
A lithium battery as a first power storage device according to the present invention includes a positive electrode, a negative electrode, and the nonaqueous electrolyte in which an electrolyte salt is dissolved in a nonaqueous solvent. Components other than the non-aqueous electrolyte, such as a positive electrode and a negative electrode, can be used without particular limitation.

(Positive electrode active material)
For example, as a positive electrode active material for a lithium secondary battery, a composite metal oxide with lithium containing one or more selected from the group consisting of cobalt, manganese, and nickel is used. These positive electrode active materials can be used alone or in combination of two or more.
As such a lithium composite metal oxide, for example, LiCoO ₂ , LiCo _1-x M _x O ₂ (where M is Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn, and One or more elements selected from the group consisting of Cu, 0.001 ≦ x ≦ 0.05), LiMn ₂ O ₄ , LiMn _1.5 Ni _0.5 O _4, LiNiO ₂ , LiCo _1-x Ni _x O ₂ (0.01 <x <1), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.8 Mn _{0 .1} Co _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , solid solution of Li ₂ MnO ₃ and LiMO ₂ (M is a transition metal such as Co, Ni, Mn, Fe, etc.) , and _LiNi 1/2 _{Mn 3/2} O One or more selected from the group consisting of is suitably mentioned, two or more is more preferable. Also, LiCoO ₂ and LiMn ₂ O ₄ , LiCoO ₂ and LiNiO ₂ , and LiMn ₂ O ₄ and LiNiO ₂ may be used in combination.

When a lithium composite metal oxide containing manganese is used as a positive electrode active material, generally, the amount of metal eluted during charging is increased, and the high-temperature charge storage characteristics are more likely to be reduced, but the lithium secondary battery according to the present invention In this case, it is possible to particularly suppress the deterioration of these electrochemical characteristics. The lithium composite metal oxide containing manganese is not particularly limited, but preferably a manganese lithium composite metal oxide having a spinel-type structure, and more preferably a spinel-type lithium manganate suppresses a decrease in electrochemical characteristics. I do. Specific examples of the positive electrode active material of the manganese lithium composite metal oxide include LiMn ₂ O ₄ , LiMn _1.5 Ni _0.5 O _4, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , and LiNi _0.5 One or more members selected from the group consisting of Mn _0.3 Co _0.2 O ₂ , LiNi _0.8 Mn _0.1 Co _0.1 O _{2, and the} like are preferably mentioned, and in particular, LiMn having a spinel structure _{. 5} Ni _0.5 O _4, it is preferable to use a LiMn ₂ O _4.
Further, a part of the manganese site of the positive electrode active material may be replaced with a multi-element, and examples of the other element that replaces the manganese site include Sn, Ni, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn, Co, Li and the like.

Further, a lithium-containing olivine-type phosphate may be used as the positive electrode active material. Particularly, a lithium-containing olivine-type phosphate containing at least one selected from iron, cobalt, nickel and manganese is preferable. Specific examples thereof include LiFePO ₄ , LiCoPO ₄ , LiNiPO ₄ , LiMnPO _{4 and the} like.
Some of these lithium-containing olivine-type phosphates may be replaced with other elements, and some of iron, cobalt, nickel, and manganese may be replaced with Co, Mn, Ni, Mg, Al, B, Ti, V, and Nb. , Cu, Zn, Mo, Ca, Sr, W, Zr, etc., which can be replaced by one or more elements selected from the group consisting of, or coated with a compound or carbon material containing these other elements. Can also. Among these, LiFePO ₄ or LiMnPO ₄ is preferred, and LiMnPO ₄ is more preferred.
Further, the lithium-containing olivine-type phosphate can be used, for example, in a mixture with the above-mentioned positive electrode active material.

Further, as the positive electrode active material for the lithium primary battery, CuO, Cu ₂ O, Ag ₂ O, Ag ₂ CrO ₄ , CuS, CuSO ₄ , TiO ₂ , TiS ₂ , SiO ₂ , SnO, V ₂ O ₅ , V ₆ _{_{_{_{O 12, VO x, Nb 2}}}} O 5, Bi 2 O 3, Bi 2 Pb 2 O 5, Sb 2 O 3, CrO 3, Cr 2 O 3, MoO 3, WO 3, SeO 2, MnO 2, Mn 2 Oxides or chalcogen compounds of one or more metal elements selected from the group consisting of O ₃ , Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , NiO, CoO ₃ , CoO, etc. _2, sulfur compounds such as SOCl _2, the general formula _(CF _x) fluorocarbon (graphite fluoride) represented by _n, and the like. Among them, MnO ₂ , V ₂ O ₅ , graphite fluoride and the like are preferable.

導電 The conductive agent for the positive electrode is not particularly limited as long as it is an electron conductive material that does not cause a chemical change. Examples include graphite such as natural graphite (flaky graphite and the like) and artificial graphite, and carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black. Further, graphite and carbon black may be appropriately mixed and used. The amount of the conductive agent added to the positive electrode mixture is preferably 1 to 10% by mass, more preferably 2 to 5% by mass.

For the positive electrode, the positive electrode active material is a conductive agent such as acetylene black or carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), a copolymer of styrene and butadiene (SBR), or a mixture of acrylonitrile and butadiene. A positive electrode mixture is prepared by mixing with a binder such as copolymer (NBR), carboxymethyl cellulose (CMC), ethylene propylene diene terpolymer and the like, adding a high boiling solvent such as 1-methyl-2-pyrrolidone and kneading the mixture. Then, the positive electrode mixture is applied to an aluminum foil or a stainless steel lath plate of a current collector, dried and pressed, and then subjected to vacuum at about 50 ° C. to 250 ° C. for about 2 hours. Can be produced by heat treatment.
The density of the part except the collector of the positive electrode is usually at 1.5 g / cm ³ or more, to further enhance the battery capacity, preferably 2 g / cm ³ or more, more preferably 3 g / cm ³ or more, more preferably Is 3.6 g / cm ³ or more. Note that the upper limit is preferably 4 g / cm ³ or less.

(Negative electrode active material)
Examples of the negative electrode active material for a lithium secondary battery include lithium metal, a lithium alloy, and a carbon material capable of occluding and releasing lithium ions (e.g., graphitizable carbon and a (002) plane having a spacing of 0.37 nm ( Nanometer) or more, non-graphitizable carbon or graphite having a (002) plane spacing of 0.34 nm or less], tin (simple), tin compound, silicon (simple), silicon compound (SiOx: x <2), Use of a silicon alloy (Si-M alloy: M is at least one selected from the group consisting of Al, Ni, Cu, Fe, Ti and Mn), a metal compound, etc., alone or in combination of two or more Can be.
Among these, it is preferable to use a highly crystalline carbon material or metal compound such as artificial graphite or natural graphite in terms of the ability to insert and extract lithium ions.

As the highly crystalline carbon material, a carbon material having a graphite-type crystal structure in which the plane spacing (d ₀₀₂ ) of the lattice plane (002) is 0.340 nm or less, particularly 0.335 to 0.337 nm is preferable.
A plurality of flat graphitic fine particles are aggregated non-parallel to each other or artificial graphite particles having a massive structure combined with each other, for example, compressive force on flake-like natural graphite particles, mechanical force such as frictional force, shear force, etc. By using the graphite particles subjected to the spheroidizing treatment, the density of the part excluding the current collector of the negative electrode can be obtained from the X-ray diffraction measurement of the negative electrode sheet when the density is 1.5 g / cm ³ or more. When the ratio I (110) / I (004) of the peak intensity I (110) of the (110) plane and the peak intensity I (004) of the (004) plane of the graphite crystal becomes 0.01 or more, the more the positive electrode active material becomes, It is preferable because it improves the metal elution amount and the charge storage characteristics, and is more preferably 0.05 or more, and even more preferably 0.1 or more. Further, since excessive treatment may reduce the crystallinity and decrease the discharge capacity of the battery, the upper limit of I (110) / I (004) is preferably 0.5 or less, more preferably 0.3 or less. preferable.
Further, it is preferable that the highly crystalline carbon material (core material) is coated with a carbon material having lower crystallinity than the core material, because the high-temperature charge storage characteristics are further improved. The crystallinity of the carbon material of the coating can be confirmed by a transmission electron microscope (TEM).
When a highly crystalline carbon material is used, it generally reacts with a non-aqueous electrolyte during charging, and tends to decrease high-temperature charge storage characteristics due to an increase in interface resistance. In this case, the high-temperature charge storage characteristics are improved.

Examples of the metal compound capable of inserting and extracting lithium ions as the negative electrode active material include Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Examples include compounds containing at least one metal element such as Cu, Zn, Ag, Mg, Sr, and Ba. These metal compounds may be used in any form such as a simple substance, an alloy, an oxide, a nitride, a sulfide, a boride, and an alloy with lithium. Is preferable because the capacity can be further increased. Among these, those containing at least one element selected from Si, Ge, and Sn are preferable, and those containing at least one element selected from Si and Sn are particularly preferable because the capacity of the battery can be further increased.

Further, a titanium composite metal oxide containing a titanium atom capable of occluding and releasing lithium ions as a negative electrode active material may be used. Since these titanium composite metal oxides have small expansion and contraction during charge and discharge and are flame-retardant, they are preferable from the viewpoint of enhancing battery safety.
Examples of the titanium composite metal oxide include at least one selected from a lithium titanium composite oxide and a niobium titanium composite oxide.
As the lithium-titanium composite oxide, a lithium-titanium composite oxide having a spinel-type crystal structure represented by a general formula Li ₄ Ti _5-xM _x O ₁₂ is preferable. Here, M is an element substituted for a Ti site, and is at least one element selected from Mn, Fe, V, and Nb.
Examples of the niobium titanium composite oxide include TiNb ₂ O ₇ , Ti ₂ Nb ₁₀ O ₂₉ , TiNb ₁₄ O ₃₇ , and TiNb ₂₄ O ₆₂ , with TiNb ₂ O ₇ being preferred.
Among the titanium composite metal oxides, lithium titanate (Li ₄ Ti ₅ O ₁₂ ) is preferable from the viewpoint of improving battery characteristics.

The negative electrode was kneaded using the same conductive agent, binder, and high boiling point solvent as in the preparation of the above positive electrode to form a negative electrode mixture, and then applied this negative electrode mixture to a copper foil or the like of a current collector. After drying, pressing and molding, it can be produced by performing a heat treatment under vacuum at a temperature of about 50 ° C. to 250 ° C. for about 2 hours.
The density of the portion of the negative electrode excluding the current collector is usually 1.1 g / cm ³ or more, and preferably 1.5 g / cm ³ or more, more preferably 1.7 g / cm ³ to further increase the battery capacity. cm ³ or more. Note that the upper limit is preferably 2 g / cm ³ or less.

In summary, when triethyl (sulfopropyl) ammonium or (tributylphosphonio) propylsulfonate is used as the zwitterion, spinel-type lithium manganate (LiMn ₂ O ₄ ) is used as the positive electrode active material and the negative electrode active material is used. It is preferable to use a titanium composite metal oxide, particularly Li ₄ Ti ₅ O ₁₂ as the substance.
When a compound represented by the above general formula (IV), (VIII), (XI) or (XII) is used as the zwitterion, a lithium composite metal oxide containing manganese is preferable as the positive electrode active material. And a manganese lithium composite metal oxide having a spinel type structure is more preferable, and spinel type lithium manganate (LiMn ₂ O ₄ ) is further preferable. As a negative electrode active material, a carbon material capable of inserting and extracting lithium, And at least one selected from titanium composite metal oxides.
When a compound represented by the above general formula (VII) or (VII-1) is used as the zwitterion, a manganese lithium composite metal oxide having a spinel structure is preferable as the positive electrode active material. Lithium oxide is more preferable, and as the negative electrode active material, a carbon material capable of inserting and extracting lithium is preferably used.

Further, as the negative electrode active material for the lithium primary battery, lithium metal or lithium alloy is given.

The structure of the lithium battery is not particularly limited, and a coin battery, a cylindrical battery, a square battery, a laminated battery, or the like having a single-layer or multiple-layer separator can be applied.
The battery separator is not particularly limited, and a single-layer or laminated microporous film, woven fabric, non-woven fabric, or the like of polyolefin such as polypropylene and polyethylene can be used.

(4) The lithium secondary battery of the present invention has excellent high-temperature charge storage characteristics even when the end-of-charge voltage is 4.2 V or higher, particularly 4.3 V or higher, and has good characteristics even at 4.4 V or higher. The discharge end voltage can be usually 2.8 V or more, and more preferably 2.5 V or more, but the lithium secondary battery of the present invention can be 2.0 V or more. The current value is not particularly limited, but is usually used in the range of 0.1 to 30C. Further, the lithium battery of the present invention can be charged and discharged at -40 to 100 ° C, preferably at -10 to 80 ° C.

In the present invention, as a countermeasure against an increase in the internal pressure of the lithium battery, a method of providing a safety valve in the battery lid or making a cut in a member such as a battery can or a gasket can be adopted. Further, as a safety measure for preventing overcharge, a current cutoff mechanism that detects the internal pressure of the battery and cuts off the current can be provided in the battery lid.

[Second power storage device (electric double layer capacitor)]
A second power storage device according to the present invention is a power storage device that includes the nonaqueous electrolytic solution of the present invention and stores energy by utilizing the electric double layer capacity of the electrolytic solution and the electrode interface. One example of the present invention is an electric double layer capacitor. The most typical electrode active material used for this electricity storage device is activated carbon. The electric double layer capacity generally increases in proportion to the surface area.

[Third power storage device]
A third power storage device according to the present invention is a power storage device that includes the non-aqueous electrolyte solution of the present invention and stores energy using a doping / dedoping reaction of an electrode. Examples of the electrode active material used in the power storage device include metal oxides such as ruthenium oxide, iridium oxide, tungsten oxide, molybdenum oxide, and copper oxide, and π-conjugated polymers such as polyacene and polythiophene derivatives. Capacitors using these electrode active materials can store energy due to the doping / dedoping reactions of the electrodes.

[Fourth power storage device (lithium ion capacitor)]
A fourth power storage device according to the present invention is a power storage device that includes the nonaqueous electrolyte solution of the present invention and stores energy by utilizing the intercalation of lithium ions into a carbon material such as graphite as a negative electrode. It is called a lithium ion capacitor (LIC). Examples of the positive electrode include one using an electric double layer between an activated carbon electrode and an electrolyte, and one using a doping / dedoping reaction of a π-conjugated polymer electrode. The electrolyte includes lithium salts such as at least LiPF _6.

[Production of lithium ion secondary battery 1]
(1) Preparation of Nonaqueous Electrolyte Solution 1 Each solvent and electrolyte salt were mixed in a predetermined amount to prepare reference electrolyte solutions shown in Tables 1 and 2. The unit M of the concentration of the electrolyte salt shown in Tables 1 and 2 indicates mol / L.
The composition of the reference electrolyte was 29.8% by mass of ethylene carbonate (EC), 53.4% by mass of methyl ethyl carbonate (MEC) [EC / MEC = 3/7 by volume ratio], and 1 of vinylene carbonate (VC). 0.0% by mass, LiPF ₆ is 8.4% by mass (0.7M), and LiN (SO ₂ F) ₂ (LiFSI) is 7.4% by mass (0.5M).
In Example 1, 0.5% by mass of 2- (triethylammonio) ethyl sulfate (compound of the structural formula 4) was added as a zwitterion to a reference electrolyte solution, and the mixture was stirred for 12 hours or more. Filtration was performed using a 45 μm membrane filter to prepare a non-aqueous electrolyte.
In Example 2, 0.43% by mass of 2-dodecyldimethyl (carboxylatomethyl) ammonium was added as a zwitterion to the reference electrolyte, and the mixture was stirred for 12 hours or more, and then a 0.45 μm membrane filter was used. And filtered to prepare a non-aqueous electrolyte 1.
The contents described in Tables 1 and 2 are values obtained by analyzing the prepared electrolyte solution using high performance liquid chromatography.

(2) Preparation of Battery 1 90% by mass of LiMn ₂ O ₄ (positive electrode active material) and 6% by mass of acetylene black were mixed, and 4% by mass of polyvinylidene fluoride (binder) was previously converted to 1-methyl-2-pyrrolidone. The mixture was added to the dissolved solution and mixed to prepare a positive electrode mixture paste. This positive electrode mixture paste was applied to one surface of an aluminum foil (current collector), dried, pressurized, and cut into a predetermined size to produce a rectangular positive electrode sheet.
Further, 98% by mass of natural graphite (negative electrode active material), 1% by mass of carboxymethyl cellulose (thickener), and 1% by mass of styrene butadiene rubber (binder) were added to a solution dissolved in water and mixed. , To prepare a negative electrode mixture paste. This negative electrode mixture paste was applied to one surface of a copper foil (current collector), dried, pressurized, and cut into a predetermined size to prepare a negative electrode sheet. Then, a positive electrode sheet, a microporous polyethylene film separator, and a negative electrode sheet were laminated in this order, and the nonaqueous electrolyte prepared in the above (1) was added to produce a laminated battery 1 shown in Tables 1 and 2.

[Production of lithium ion secondary battery 2]
(1) Preparation of Nonaqueous Electrolyte Solution 2 Each solvent and an electrolyte salt were mixed in a fixed amount to prepare a reference electrolyte solution shown in Table 3.
The composition indicated by the mass ratio of the reference electrolyte was 32.2 mass% of propylene carbonate (PC), 52.0 mass% of diethyl carbonate (DEC) [PC / DEC = 1/2 by volume ratio], and LiPF ₆ It becomes 15.8 mass% (1.3M).
0.5 mass% of triethyl (sulfopropyl) ammonium was added as a zwitterion to the reference electrolyte, and the mixture was stirred for 12 hours or more, and then filtered using a 0.45 μm membrane filter to obtain a nonaqueous electrolyte. 2 was prepared.

(2) Preparation of Battery 2 90% by mass of LiMn ₂ O ₄ (positive electrode active material) and 6% by mass of acetylene black were mixed, and 4% by mass of polyvinylidene fluoride (binder) was previously converted to 1-methyl-2-pyrrolidone. The mixture was added to the dissolved solution and mixed to prepare a positive electrode mixture paste. This positive electrode mixture paste was applied to one surface of an aluminum foil (current collector), dried, pressurized, and cut into a predetermined size to produce a rectangular positive electrode sheet.
Also, 95% by mass of lithium titanate (Li ₄ Ti ₅ O ₁₂ : negative electrode active material) and 2% by mass of a carbon-based conductive agent are mixed, and 3% by mass of polyvinylidene fluoride (binder) is added to 1-methyl- The mixture was added to and mixed with the solution dissolved in 2-pyrrolidone to prepare a negative electrode mixture paste. This negative electrode mixture paste was applied to one surface of an aluminum foil (current collector), dried, pressurized, and cut into a predetermined size to prepare a negative electrode sheet. Then, a positive electrode sheet, a microporous polyethylene film separator, and a negative electrode sheet were laminated in this order, and the non-aqueous electrolyte prepared in the above (1) was added to produce a laminated battery 2 shown in Table 3.

(Evaluation of discharge capacity recovery rate, gas generation amount, AC resistance after storage at high temperature charge)
Using the battery prepared by the above method, charge / discharge was performed in a 45 ° C. constant temperature bath at a constant current and a constant voltage of 0.2 C at a charge end voltage of 4.2 V and at a discharge end voltage of 2.7 V for three cycles. In this specification, up to the three cycles of charging and discharging are defined as pretreatment. After charging for 1 hour at a constant current value of 0.2C in a constant temperature bath of 45 ° C, leaving it to stand in a constant temperature bath of 60 ° C for 20 days, terminating in a constant temperature bath of 45 ° C under a constant current of 0.2C. The battery was discharged to a voltage of 2.7V. In this specification, a high-temperature preservation test is defined as a process from charging at a constant current of 0.2 C at 45 ° C. for one hour to standing at 60 ° C. and discharging at 45 ° C. Tables 1 and 2 show the discharge capacity recovery rate, gas generation amount, and AC resistance value after high-temperature charge storage.
The discharge capacity recovery rate (%) was calculated by the following equation.
Discharge capacity recovery rate (%) = (discharge capacity after high-temperature storage test / discharge capacity before high-temperature storage test) × 100
The discharge capacity in the above formula means that charge and discharge were performed at a constant current of 0.2 C and a constant voltage of 4.2 V and a discharge end voltage of 2.7 V in a constant temperature bath at 45 ° C. before and after a high-temperature storage test. It is the discharge capacity at the time. The discharge capacity recovery rate (%) is an index indicating the degree of battery capacity reduction during high-temperature storage.
The gas generation amount is a relative value when the gas amount after the high-temperature storage test is measured by the Archimedes method and the gas amount generated in Comparative Example 1 is 100%.
The AC resistance value was obtained by measuring the resistance value of the real part of the AC impedance at 100 mHz in a constant temperature bath of 50% and 0 ° C. before and after the high-temperature storage test, and setting the value measured in Comparative Example 1 to 100%. It is a relative value.

As is clear from Table 1, in Example 1 using the non-aqueous electrolyte of the present invention, the decrease in battery capacity during high-temperature storage was smaller than that in Comparative Example 1, and as a result, the discharge capacity after high-temperature storage. It can be seen that the recovery rate is improved, and the amount of generated gas and AC resistance can be suppressed.

As is clear from Table 2, in Example 2 using the non-aqueous electrolyte of the present invention, the decrease in battery capacity during high-temperature storage was smaller than in Comparative Examples 1 and 2, and as a result, high-temperature storage was achieved. It is understood that the discharge capacity recovery rate can be improved later.

As is clear from Table 3, in Example 3 using the non-aqueous electrolyte of the present invention, the decrease in battery capacity during high-temperature storage was smaller than that in Comparative Example 3, and as a result, the discharge capacity after high-temperature storage. It can be seen that the recovery rate can be improved.

The power storage device using the non-aqueous electrolyte of the present invention can greatly improve high-temperature charge storage characteristics, and is useful as a power storage device such as a lithium secondary battery having excellent electrochemical characteristics.

Claims

A non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a non-aqueous solvent, comprising a zwitterion represented by the following general formula (I).

(In the formula (I), Q + is a cationic group represented by the following formula (II) or (III).
L 1 is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or 1 to 4 carbon atoms. Represents an alkyleneoxy group.
A - anionic group represented by is a sulfonate or carboxylato group. )

(In the formula (II), R 1 to R 3 each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, It represents a fluorinated alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 3 to 15 carbon atoms, or a fluorinated alkynyl group having 3 to 15 carbon atoms.
In the formula (III), R 4 to R 6 each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site with L 1. )
The non-aqueous electrolyte according to claim 1, wherein the zwitterion is at least one selected from a compound represented by the following general formula (IV) and a compound represented by the following general formula (VII).

(In the formula (IV), Q + is a cationic group represented by the following formula (V) or (VI).
L 2 represents a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or an alkyleneoxy group having 1 to 4 carbon atoms. )

(In the formula (V), R 7 to R 9 are each independently an alkyl group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, It represents a fluorinated alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, or a fluorinated alkynyl group having 3 to 5 carbon atoms.
In the formula (VI), R 10 to R 12 each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site of the L 2. )

(In the formula (VII), L 3 represents an alkylene group having 1 to 5 carbon atoms.
R 13 to R 15 each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, or a fluorinated alkenyl having 2 to 15 carbon atoms A alkynyl group having 3 to 15 carbon atoms or a fluorinated alkynyl group having 3 to 15 carbon atoms. However, at least one of R 13 to R 15 is an alkyl group having 3 to 15 carbon atoms. )
3. The non-aqueous electrolyte according to claim 1, wherein the zwitterion is a compound represented by the following general formula (VIII).

(In the formula (VIII), Q + is a cationic group represented by the following formula (IX) or (X).
L 4 represents an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, or a fluorinated alkenylene group having 2 to 5 carbon atoms. )

(In the formula (IX), R 16 to R 18 each independently represent an alkyl group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, It represents a fluorinated alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, or a fluorinated alkynyl group having 3 to 5 carbon atoms.
In the formula (X), R 19 to R 21 each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site of the L 4. )
The non-aqueous electrolyte according to claim 3, wherein the zwitterion is at least one selected from a compound represented by the following general formula (XI) and a compound represented by the following general formula (XII).

(L 5 in the formula (XI) and L 6 in the formula (XII) represent an alkylene group having 2 or 3 carbon atoms.
In the formula (XI), R 16 to R 18 each independently represent an alkyl group having 1 to 3 carbon atoms.
In the formula (XII), R 19 to R 21 each independently represent an alkyl group having 1 to 3 carbon atoms or a dimethylamino group. )
The zwitterions are 2- (trimethylammonio) ethyl sulfate, 2- (triethylammonio) ethyl sulfate, 2- (tripropylammonio) ethyl sulfate, 3- (trimethylammonio) propyl sulfate, 3- (triethyl) From (ammonio) propyl sulfate, 3- (tripropylammonio) propyl sulfate, 2- (tributylphosphonio) ethyl sulfate, 2- (trisdimethylaminophosphonio) ethyl sulfate, and 3- (tributylphosphonio) propyl sulfate The non-aqueous electrolyte according to claim 3, wherein the non-aqueous electrolyte is at least one selected from the group consisting of:
3. The non-aqueous electrolyte according to claim 1, wherein the zwitterion is a compound represented by the following general formula (VII-1).

(In the formula (VII-1), L 3 is a methylene group, R 13 to R 15 are each independently an alkyl group having 1 to 15 carbon atoms, and at least one of R 13 to R 15 is a carbon atom group. 3 to 15 alkyl groups.)
A zwitterion represented by the general formula (VII-1), 2-butyldimethyl (carboxylatomethyl) ammonium, 2-hexyldimethyl (carboxylatomethyl) ammonium, 2-octyldimethyl (carboxylatomethyl) ammonium, 7. The non-aqueous electrolyte according to claim 6, wherein the non-aqueous electrolyte is at least one selected from the group consisting of 2-decyldimethyl (carboxylatomethyl) ammonium and 2-dodecyldimethyl (carboxylatomethyl) ammonium.
8. The non-aqueous electrolyte according to claim 1, wherein the non-aqueous solvent contains a cyclic carbonate and a chain ester.
The non-aqueous electrolyte contains at least one lithium salt selected from an inorganic lithium salt, a lithium salt having a fluorinated alkyl group, a lithium imide salt having a fluorine atom, and a lithium salt having an oxalic acid structure. 9. The non-aqueous electrolyte according to any one of 1 to 8.
10. The non-aqueous electrolyte according to any one of claims 1 to 9, wherein the non-aqueous electrolyte contains an inorganic lithium salt and a lithium imide salt having a fluorine atom.
A power storage device including a positive electrode, a negative electrode, and a non-aqueous electrolyte in which an electrolyte salt is dissolved in a non-aqueous solvent, wherein the non-aqueous electrolyte contains a zwitterion represented by the following general formula (I). An electricity storage device characterized by the above-mentioned.

(In the formula (I), Q + is a cationic group represented by the following formula (II) or (III).
L 1 is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkenylene group having 2 to 5 carbon atoms, a fluorinated alkenylene group having 2 to 5 carbon atoms, or 1 to 4 carbon atoms. Represents an alkyleneoxy group.
A - anionic group represented by is a sulfonate or carboxylato group. )

(In the formula (II), R 1 to R 3 each independently represent an alkyl group having 1 to 15 carbon atoms, a fluorinated alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, It represents a fluorinated alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 3 to 15 carbon atoms, or a fluorinated alkynyl group having 3 to 15 carbon atoms.
In the formula (III), R 4 to R 6 each independently represent an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a fluorinated alkyl group having 1 to 5 carbon atoms, A fluorinated alkoxy group having 2 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkenyloxy group having 2 to 5 carbon atoms, a fluorinated alkenyloxy group having 2 to 5 carbon atoms, an alkynyl group having 3 to 5 carbon atoms, It represents an alkynyloxy group having 3 to 5, a fluorinated alkynyl group having 3 to 5 carbon atoms, a fluorinated alkynyloxy group having 3 to 5 carbon atoms, a dimethylamino group, or a diethylamino group.
* Indicates a binding site with L 1. )
The power storage device according to claim 11, wherein the active material of the positive electrode includes a lithium composite metal oxide.
The active material of the positive electrode is a lithium composite metal oxide containing manganese,
The power storage device according to claim 11 or 12, wherein the negative electrode active material is at least one selected from a carbon material capable of inserting and extracting lithium and a titanium composite metal oxide.
14. The power storage device according to claim 13, wherein the active material of the positive electrode is a manganese lithium composite metal oxide having a spinel structure, and the active material of the negative electrode is a titanium composite metal oxide.