WO2023119987A1

WO2023119987A1 - Nonaqueous electrolyte solution, electrochemical device precursor, electrochemical device, and method for producing electrochemical device

Info

Publication number: WO2023119987A1
Application number: PCT/JP2022/042931
Authority: WO
Inventors: 雄介清水
Original assignee: 三井化学株式会社
Priority date: 2021-12-20
Filing date: 2022-11-18
Publication date: 2023-06-29

Abstract

A nonaqueous electrolyte solution according to the present disclosure contains a compound (I) which is represented by formula (I), a specific compound (A), a nonaqueous solvent and an electrolyte. The content of the compound (I) is 0.01% by mass to 5% by mass relative to the total amount of the nonaqueous electrolyte solution.　(I): R¹¹-X-R¹²-C≡N In formula (I), X represents -S(=O)₂- (a sulfone structure), -O-S(=O)-O- (a sulfite structure) or -O-C(=O)-C(=O)-O- (an oxalate structure); R¹¹ represents a cyanoalkyl group or the like having 2 to 5 carbon atoms, a 2-alkynyl group having 3 to 5 carbon atoms, or an alkyl group having 1 to 6 carbon atoms; and R¹² represents an alkylene group having 1 to 4 carbon atoms.

Description

Non-aqueous electrolyte, electrochemical device precursor, electrochemical device, and electrochemical device manufacturing method

The present disclosure relates to a non-aqueous electrolyte, an electrochemical device precursor, an electrochemical device, and a method for manufacturing an electrochemical device.

Lithium-ion secondary batteries are attracting attention as batteries with high energy density.

Patent Document 1 discloses a non-aqueous electrolyte. The non-aqueous electrolytic solution disclosed in Patent Document 1 contains 0.01 to 5% by mass of a specific nitrile compound in the non-aqueous electrolytic solution in which an electrolyte salt is dissolved in a non-aqueous solvent. Patent Document 1 describes specific nitrile compounds such as bis(2-cyanoethyl)sulfite, bis(2-cyanoethyl)oxalate, bis(2-cyanoethyl)sulfone, 2-cyanoethyl-2-propynylsulfite, 2-cyanoethyl- Specifically disclosed are 2-propynyl oxalate or 2-cyanoethyl methyl sulfite.

Patent Document 1: International Publication No. 2010/018814

The battery characteristics of electrochemical devices deteriorate with repeated charging and discharging. Therefore, there is a demand for a non-aqueous electrolytic solution capable of suppressing deterioration in battery characteristics of an electrochemical device due to repeated charging and discharging. In other words, even if the electrochemical device is stored for a long period of time in a high-temperature environment (that is, even if the electrochemical device is exposed to an environment that accelerates deterioration of electrical properties), it suppresses a decrease in capacity and an increase in DC resistance. There is a demand for a non-aqueous electrolyte that can

In view of the above circumstances, the present disclosure provides a non-aqueous electrolytic solution, an electrochemical device precursor, an electrochemical device precursor, and an electrochemical device that can suppress a decrease in capacity and an increase in DC resistance even when the electrochemical device is stored for a long time in a high-temperature environment. An object of the present invention is to provide a method for manufacturing a chemical device and an electrochemical device.

The means for solving the above problems include the following embodiments.

<1> A non-aqueous electrolyte,
including a compound (I) represented by the following formula (I), a non-aqueous solvent, an electrolyte, and a compound (A),
The compound (A) is a group consisting of a compound (II) represented by the following formula (II), a compound (III) represented by the following formula (III), and lithium monofluorophosphate and lithium difluorophosphate. At least one selected from the group consisting of a compound (VI) that is at least one selected from and a compound (V) represented by the following formula (V),
A non-aqueous electrolytic solution in which the content of the compound (I) is 0.01% by mass to 5% by mass relative to the total amount of the non-aqueous electrolytic solution.
R ¹¹ -X-R ¹² -C≡N (I)
(In formula (I), X is -S (=O) ₂ - (sulfone structure), -OS (=O) -O- (sulfite structure), or -OC (=O) - C (= O) -O- (oxalate structure),
R ¹¹ represents a cyanoalkyl group having 2 to 5 carbon atoms, a 2-alkynyl group having 3 to 5 carbon atoms, or an alkyl group having 1 to 6 carbon atoms,
R ¹² represents an alkylene group having 1 to 4 carbon atoms. )

[In formula (II), R ²¹ represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group, and R ²² represents an alkylene group having 1 to 6 carbon atoms. , represents a group represented by the above formula (ii-1) or a group represented by the above formula (ii-2). * indicates the binding position. In formula (ii-2) above, R ²³ represents a group represented by an alkyl group having 1 to 6 carbon atoms.
In formula (III), ^R31 and ^R32 are each independently a hydrogen atom, a methyl group, an ethyl group, or a propyl group.
In formula (V), M represents an alkali metal, b is an integer of 1-3, m is an integer of 1-4, n is an integer of 0-8, and q represents 0 or 1. R ⁵¹ is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a heteroatom, and when q is 1 and m is 2 to 4, each of m R ⁵¹ may be bonded.), and R ⁵² is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups are , the structure may contain a substituent or a heteroatom, and when n is 2 to 8, each of the n R ⁵² may combine to form a ring.), and Q ¹ and ^Q2 each independently represent an oxygen atom or a carbon atom. ]
<2> The non-aqueous electrolytic solution according to <1>, wherein X is -S(=O) ₂ - (sulfone structure).
<3> The non-aqueous electrolytic solution according to <1> or <2> above, wherein the compound (I) is a compound (I-1) represented by the following formula (I-1).

<4> a case;
a positive electrode, a negative electrode, a separator, and an electrolytic solution housed in the case;
with
the positive electrode is a positive electrode capable of intercalating and deintercalating lithium ions;
the negative electrode is a negative electrode capable of intercalating and deintercalating lithium ions;
An electrochemical device precursor, wherein the electrolytic solution is the non-aqueous electrolytic solution according to any one of <1> to <3>.
<5> The electrochemical device precursor according to <4>, wherein the positive electrode contains a lithium-containing composite oxide represented by the following formula (X) as a positive electrode active material.
_{LiNiaCobMncO2} _... _Formula ₍ X)
[In formula (X), a, b and c are each independently greater than 0 and less than 1, and the sum of a, b and c is 0.99 or more and 1.00 or less. ]
<6> A step of preparing the electrochemical device precursor according to <4> or <5>;
and a step of charging and discharging the electrochemical device precursor.
<7> An electrochemical device obtained by charging and discharging the electrochemical device precursor according to <4> or <5>.

According to the present disclosure, a non-aqueous electrolyte, an electrochemical device precursor, an electrochemical device, which can suppress a decrease in capacity and an increase in direct current resistance even when the electrochemical device is stored for a long time in a high-temperature environment, and methods of manufacturing electrochemical devices are provided.

1 is a cross-sectional view of an electrochemical device precursor according to an embodiment of the present disclosure; FIG.

In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.
As used herein, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. means
In this specification, the term "process" is not only an independent process, but also includes the term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. be

[Non-aqueous electrolyte]
The non-aqueous electrolytic solution according to this embodiment will be described.

The non-aqueous electrolyte is suitably used as an electrolyte for electrochemical devices. Electrochemical devices include lithium ion secondary batteries. Details of the electrochemical device will be described later with reference to FIG.

The non-aqueous electrolytic solution according to the present embodiment is a non-aqueous electrolytic solution, a compound (I) represented by the following formula (I) (hereinafter referred to as "nitrile compound (I)"), and a non-aqueous solvent , an electrolyte, and a compound (A). The compound (A) includes a compound (II) represented by the following formula (II) (hereinafter referred to as "cyclic sulfone compound (II)") and a compound (III) represented by the following formula (III) ( hereinafter referred to as "cyclic carbonate compound (III)") and compound (VI) which is at least one selected from the group consisting of lithium monofluorophosphate and lithium difluorophosphate (hereinafter referred to as "lithium fluorophosphate at least one selected from the group consisting of a compound (VI)") and a compound (V) represented by the following formula (V) (hereinafter referred to as a "cyclic dicarbonyl compound (V)") is. The content of the compound (I) is 0.01% by mass to 5% by mass with respect to the total amount of the non-aqueous electrolyte. Details of compound (I) will be described later. The details of the cyclic sulfone compound (II), the cyclic carbonate compound (III), the lithium fluorophosphate compound (VI), and the cyclic dicarbonyl compound (V) will be described later.
R ¹¹ -X-R ¹² -C≡N (I)

Since the non-aqueous electrolyte has the above structure, even if the electrochemical device is stored for a long period of time in a high-temperature environment, a decrease in capacity and an increase in DC resistance are suppressed.
This effect is presumed to be due to the following reasons, but is not limited thereto.
When the electrochemical device of the present disclosure is charged and/or discharged (hereinafter referred to as “charge and discharge”), a solid electrolyte interphase (SEI) film (hereinafter referred to as “SEI”) is formed on the surface of the negative electrode and the surface of the positive electrode. ) is formed.
Hereinafter, when the SEI film of the negative electrode and the SEI film of the positive electrode are not distinguished, the SEI film of the negative electrode and the SEI film of the positive electrode may be simply referred to as “SEI film”.
The SEI film is considered to be mainly formed by lithium ions in the non-aqueous electrolyte and decomposition products of the non-aqueous electrolyte that are decomposed by charging and discharging of the electrochemical device.
It is thought that when the SEI film is formed, even if the electrochemical device is stored in a high-temperature environment for a long period of time, side reactions other than the original battery reaction are less likely to proceed during the charge-discharge cycle of the electrochemical device. A battery reaction indicates a reaction in which lithium ions move in and out (intercalate) between a positive electrode and a negative electrode. The side reaction includes a reductive decomposition reaction of the non-aqueous electrolyte by the negative electrode, an oxidative decomposition reaction of the non-aqueous electrolyte by the positive electrode, elution of the metal element in the positive electrode active material, and the like.
In the electrochemical device using the non-aqueous electrolyte according to the present embodiment, the SEI film is difficult to thicken even in charge-discharge cycles after being stored in a high-temperature environment. Therefore, lithium ions in the non-aqueous electrolyte are less likely to be consumed.
For the reasons described above, the non-aqueous electrolytic solution according to the present embodiment can suppress a decrease in capacity and an increase in DC resistance even when an electrochemical device is stored for a long period of time in a high-temperature environment.

<Nitrile compound (I)>
The non-aqueous electrolyte contains a nitrile compound (I) represented by the following formula (I).

R ¹¹ -X-R ¹² -C≡N (I)
In formula (I), X is -S (=O) ₂ - (sulfone structure), -OS (=O) -O- (sulfite structure), or -OC (=O) -C (=O)-O- (oxalate structure). R ¹¹ represents a cyanoalkyl group having 2 to 5 carbon atoms, a 2-alkynyl group having 3 to 5 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. R ¹² represents an alkylene group having 1 to 4 carbon atoms.

In formula (I), each of a cyanoalkyl group having 2 to 5 carbon atoms, a 2-alkynyl group having 3 to 5 carbon atoms, and an alkyl group having 1 to 6 carbon atoms represented by R ¹¹ is a linear carbonized It may be a hydrogen group or a branched hydrocarbon group.
Examples of cyanoalkyl groups having 2 to 5 carbon atoms include cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, 1-cyanoethyl group, 2-cyano-1-methylethyl group, 2- cyano-2-methylethyl group, 1,1-dimethylcyanomethyl group and the like.
Examples of the 2-alkynyl group having 3 to 5 carbon atoms include 2-propynyl group, 1-methyl-2-propynyl group, 1,1-dimethyl-2-propynyl group and the like.
Examples of alkyl groups having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group and the like.
R ¹¹ is preferably a 2-alkynyl group having 3 to 5 carbon atoms or an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and 1 to 6 carbon atoms. 3 alkyl groups are more preferred.

In formula (I), the C 1-4 alkylene group represented by R ¹² may be either a linear hydrocarbon group or a branched hydrocarbon group. Examples of linear alkylene groups include methylene group, ethylene group, trimethylene group, tetramethylene group, ethylidene group, propylidene group, 1-methylethylene group, 2-methylethylene group, 1-methylethylidene group and the like. be done.
R ¹² is preferably a methylene group.

These nitrile compounds (I) may be used alone or in combination.

X is preferably -S(=O) ₂ - (sulfone structure). Thereby, the Li ion conductivity inside the SEI film can be effectively increased. As a result, the battery resistance of the electrochemical device can be reduced.

Specific examples of the compound (I) where X is -S(=O) ₂ - (sulfone structure) include bis(cyanoalkyl)sulfones, cyanoalkyl-2-propynylsulfones, cyanoalkylsulfones and the like. is mentioned.

Bis(cyanoalkyl)sulfones include bis(cyanomethyl)sulfone, bis(2-cyanoethyl)sulfone, bis(3-cyanopropyl)sulfone and the like.
Cyanoalkyl-2-propynylsulfones include cyanomethyl-2-propynylsulfone, 2-cyanoethyl-2-propynylsulfone, 3-cyanopropyl-2-propynylsulfone and the like.

Cyanoalkylsulfones include cyanomethylmethylsulfone, 2-cyanoethylmethylsulfone, 3-cyanopropylmethylsulfone, 4-cyanobutylmethylsulfone, 1-cyanoethylmethylsulfone, (2-cyano-1-methylethyl)methylsulfone , 2-cyano-2-methylethylmethylsulfone, cyanomethylethylsulfone, 2-cyanoethylethylsulfone, 3-cyanopropylethylsulfone, 4-cyanobutylethylsulfone, 1-cyanoethylethylsulfone, 2-cyano-1-methyl ethylethylsulfone, 2-cyano-2-methylethylethylsulfone, 2-cyanoethyl-n-propylsulfone, 2-cyanoethyl-n-butylsulfone and the like.
Cyanoalkylsulfones are preferred as compound (I) when X is -S(=O) ₂ - (sulfone structure).

Among them, compound (I) is preferably compound (I-1) represented by the following formula (I-1) (ie, cyanomethylmethylsulfone). This improves the reactivity of the molecules in the vicinity of the electrode. As a result, the formation reaction of the SEI film can be caused efficiently.
Hereinafter, the compound represented by formula (I-1) is referred to as "nitrile compound (I-1)".

The non-aqueous electrolyte may contain only one type of nitrile compound (I), or may contain two or more types.

The content of the nitrile compound (I) is 0.01% by mass to 5% by mass with respect to the total amount of the non-aqueous electrolyte. When the content of the nitrile compound (I) is within the above range, an appropriate SEI film is likely to be formed on the surface of the negative electrode and the surface of the positive electrode, and even if the electrochemical device is stored for a long time in a high-temperature environment, the capacity is maintained. It is possible to suppress a decrease in the current and an increase in the DC resistance.
The upper limit of the content of the nitrile compound (I) is preferably 3% by mass, more preferably 2% by mass, still more preferably 1.5% by mass, relative to the total amount of the non-aqueous electrolyte.
The lower limit of the content of the nitrile compound (I) is preferably 0.05% by mass, more preferably 0.1% by mass, still more preferably 0.2% by mass, particularly preferably 0.3% by weight, most preferably 0.5% by weight.

<Non-aqueous solvent>
The non-aqueous electrolyte contains a non-aqueous solvent. As the non-aqueous solvent, various known solvents can be appropriately selected. Only one type of non-aqueous solvent may be used, or two or more types may be used.

Non-aqueous solvents include, for example, cyclic carbonates, fluorine-containing cyclic carbonates, chain carbonates, fluorine-containing chain carbonates, aliphatic carboxylic acid esters, fluorine-containing aliphatic carboxylic acid esters, and γ-lactones. , fluorine-containing γ-lactones, cyclic ethers, fluorine-containing cyclic ethers, chain ethers, fluorine-containing chain ethers, nitriles, amides, lactams, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide , dimethyl sulfoxide phosphoric acid, and the like.

Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).
Examples of fluorine-containing cyclic carbonates include fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate and the like.
Examples of chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), dipropyl carbonate (DPC) and the like. mentioned.
Examples of fluorine-containing linear carbonates include methyl 2,2,2-trifluoroethyl carbonate and the like.
Examples of aliphatic carboxylic acid esters include methyl formate, methyl acetate, methyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylbutyrate, ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, ethyl isobutyrate, trimethyl and ethyl butyrate.
Examples of fluorine-containing aliphatic carboxylic acid esters include methyl difluoroacetate, methyl 3,3,3-trifluoropropionate, ethyl difluoroacetate, and 2,2,2-trifluoroethyl acetate.
Examples of γ-lactones include γ-butyrolactone and γ-valerolactone.
Cyclic ethers include, for example, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane and the like.
Examples of chain ethers include 1,2-ethoxyethane (DEE), ethoxymethoxyethane (EME), diethyl ether, 1,2-dimethoxyethane, 1,2-dibutoxyethane and the like.
_Examples _of _fluorine _- _containing _chain _ethers _include _{HCF2CF2CH2OCF2CF2H} _, _{CF3CF2CH2OCF2CF2H} _, _{HCF2CF2CH2OCF2CFHCF3} _, _CF3CF2 _{_} _{_} _{CH2OCF2CFHCF3} _, _C6F13OCH3 _, _C6F13OC2H5 _, _C8F17OCH3 _, _C8F17OC2H5 _, _CF3CFHCF2CH ₍ _CH3 ₎ _OCF2 _{_} _{_} _{_} _{_} _{_} _{_} _CFHCF3 _, _HCF2CF2OCH ₍ _C2H5 ₎ ₂ _, _HCF2CF2OC4H9 _, _{HCF2CF2OCH2CH} ₍ _C2H5 ₎ ₂ _, _{HCF2CF2OCH2CH} ₍ _CH3 _{_} ) ₂ and the like.
Examples of nitriles include acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile and the like.
Examples of amides include N,N-dimethylformamide and the like.
Examples of lactams include N-methylpyrrolidinone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone and the like.

The non-aqueous solvent preferably contains at least one selected from the group consisting of cyclic carbonates, fluorine-containing cyclic carbonates, chain carbonates, and fluorine-containing chain carbonates. In this case, the total ratio of cyclic carbonates, fluorine-containing cyclic carbonates, chain carbonates, and fluorine-containing chain carbonates is preferably 50% by mass or more and 100% by mass or less with respect to the total amount of the non-aqueous solvent. , more preferably 60% by mass or more and 100% by mass or less, still more preferably 80% by mass or more and 100% by mass or less.

The non-aqueous solvent preferably contains at least one selected from the group consisting of cyclic carbonates and chain carbonates. In this case, the total ratio of cyclic carbonates and chain carbonates in the non-aqueous solvent is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass, relative to the total amount of the non-aqueous solvent. 100 mass % or less, more preferably 80 mass % or more and 100 mass % or less.

The upper limit of the content of the nonaqueous solvent is preferably 99% by mass, preferably 97% by mass, more preferably 90% by mass, relative to the total amount of the nonaqueous electrolyte.
The lower limit of the content of the nonaqueous solvent is preferably 60% by mass, more preferably 70% by mass, relative to the total amount of the nonaqueous electrolyte.

The intrinsic viscosity of the non-aqueous solvent is preferably 10.0 mPa·s or less at 25°C from the viewpoint of further improving the dissociation of the electrolyte and the mobility of ions.

<Electrolyte>
The non-aqueous electrolyte contains an electrolyte.

The non-aqueous electrolyte preferably contains at least one of a fluorine-containing lithium salt (hereinafter sometimes referred to as a "fluorine-containing lithium salt") and a fluorine-free lithium salt as an electrolyte.

Examples of fluorine-containing lithium salts include inorganic acid anion salts and organic acid anion salts.
Examples of inorganic acid anion salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium hexafluorotantalate ( LiTaF ₆ ) and the like.
Examples of organic acid anion salts include lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ). Among them, LiPF ₆ is particularly preferable as the fluorine-containing lithium salt.
Lithium salts containing no fluorine include lithium perchlorate (LiClO ₄ ), lithium tetrachloride aluminumate (LiAlCl ₄ ), lithium decachlorodecaborate (Li ₂ B ₁₀ Cl ₁₀ ), and the like.

When the fluorine-containing lithium salt contains lithium hexafluorophosphate (LiPF ₆ ), the content of lithium hexafluorophosphate (LiPF ₆ ) is preferably 50% by mass or more and 100% by mass with respect to the total amount of the electrolyte. Below, more preferably 60% by mass or more and 100% by mass or less, still more preferably 80% by mass or more and 100% by mass or less.

The concentration of the electrolyte in the non-aqueous electrolyte is preferably 0.1 mol/L or more and 3 mol/L or less, more preferably 0.5 mol/L or more and 2 mol/L or less.

<Compound (A)>
The non-aqueous electrolyte contains compound (A).
The compound (A) is selected from the group consisting of a cyclic sulfone compound (II), a cyclic carbonate compound (III), a lithium fluorophosphate compound (VI), and a cyclic dicarbonyl compound (V). At least one.

The content of the compound (A) is preferably within the following range from the viewpoint of improving the properties of the electrochemical device after high temperature storage.
The content of compound (A) is preferably 0.10% by mass to 10.0% by mass with respect to the total amount of the non-aqueous electrolyte.
The upper limit of the content of compound (A) is preferably 10.0% by mass, more preferably 5.0% by mass, still more preferably 3.0% by mass, relative to the total amount of the non-aqueous electrolyte.
The lower limit of the content of compound (A) is preferably 0.10% by mass, more preferably 0.20% by mass, still more preferably 0.30% by mass, relative to the total amount of the non-aqueous electrolyte.

Each of the cyclic sulfone compound (II), the cyclic carbonate compound (III), the lithium fluorophosphate compound (VI), and the cyclic dicarbonyl compound (V) will be described below.

(Cyclic sulfone compound (II))
Cyclic sulfone compound (II) is represented by the following formula (II).

In formula (II), R ²¹ represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group; R ²² represents an alkylene group having 1 to 6 carbon atoms; It represents a group represented by the formula (ii-1) or a group represented by the formula (ii-2). * indicates the binding position. In formula (ii-2) above, R ²³ represents a group represented by an alkyl group having 1 to 6 carbon atoms.

Since the non-aqueous electrolyte further contains the cyclic sulfone compound (II) in addition to the nitrile compound (I), even if the electrochemical device is stored for a long period of time in a high-temperature environment, the capacity is reduced and the DC resistance is reduced. Increase can be suppressed more.
This effect is presumed to be due to the following reasons.
When an electrochemical device is produced using a non-aqueous electrolytic solution, in the production process (for example, the aging step described later), the reaction products are a cyclic sulfone compound (II) and a compound produced from the electrolyte (for example, LiF ). This further enhances the stability of the electrochemical device in a high temperature environment. As a result, an increase in DC resistance and a decrease in capacity of the electrochemical device are further suppressed even in charge-discharge cycles after the electrochemical device has been stored in a high-temperature environment for a long period of time.

In formula (II), R ²¹ is preferably an alkylene group having 1 to 3 carbon atoms, a vinylene group, or an oxygen atom, more preferably a trimethylene group, a vinylene group, or an oxygen atom.

In formula (II), R ²² is preferably a group represented by formula (ii-1) above.

Specific examples of the cyclic sulfone compound (II) include compounds represented by the following formulas (II-1) to (II-8). Hereinafter, the compound represented by formula (II-1) is referred to as "cyclic sulfone compound (II-1)".

The non-aqueous electrolyte may contain only one type of cyclic sulfone compound (II), or may contain two or more types.

When the non-aqueous electrolyte contains the cyclic sulfone compound (II), the content of the cyclic sulfone compound (II) is preferably within the following range.
The content of the cyclic sulfone compound (II) is preferably 0.10% by mass to 10.0% by mass with respect to the total amount of the non-aqueous electrolyte.
The upper limit of the content of the cyclic sulfone compound (II) is preferably 10.0% by mass, more preferably 5.0% by mass, even more preferably 3.0% by mass, particularly preferably 3.0% by mass, based on the total amount of the non-aqueous electrolyte. is 2.0% by mass. If the upper limit of the content of the cyclic sulfone compound (II) is within the above range, it is possible to suppress an increase in the thickness of the SEI film while suppressing the decomposition of the non-aqueous solvent on the positive electrode or the negative electrode. As a result, the properties of the electrochemical device after high temperature storage are improved.
The lower limit of the content of the cyclic sulfone compound (II) is preferably 0.10% by mass, more preferably 0.20% by mass, still more preferably 0.30% by mass, relative to the total amount of the non-aqueous electrolyte. If the lower limit of the content of the cyclic sulfone compound (II) is within the above range, an SEI film having a thickness capable of suppressing decomposition of the non-aqueous solvent in the non-aqueous electrolyte is formed. As a result, the properties of the electrochemical device after high temperature storage are improved.

(Cyclic carbonate compound (III))
The cyclic carbonate compound (III) is represented by the following formula (III).

In formula (III), ^R31 and ^R32 each independently represent a hydrogen atom, a methyl group, an ethyl group, or a propyl group.

In addition to the nitrile compound (I), the non-aqueous electrolyte further contains the cyclic carbonate compound (III), so that even if the electrochemical device is stored for a long time in a high temperature environment, the capacity will not decrease and the DC resistance will not decrease. increase can be further suppressed.
This effect is presumed to be due to the following reasons.
The cyclic carbonate compound (III) is reductively decomposed by the negative electrode before the non-aqueous electrolyte is reductively decomposed on the negative electrode even in charge-discharge cycles after being stored in a high-temperature environment, and easily forms an SEI film. . This suppresses decomposition of the non-aqueous electrolyte at the negative electrode. As a result, the increase in DC resistance of the electrochemical device is further suppressed.

Specific examples of the cyclic carbonate compounds (III) include compounds represented by the following formulas (III-1) to (III-7). A compound represented by the formula (III-1) is referred to as a "cyclic carbonate compound (III-1)".

The non-aqueous electrolyte may contain only one type of cyclic carbonate compound (III), or may contain two or more types.

When the non-aqueous electrolyte contains the cyclic carbonate compound (III), the content of the cyclic carbonate compound (III) is preferably within the following range.
The content of the cyclic carbonate compound (III) is preferably 0.10% by mass to 10.0% by mass with respect to the total amount of the non-aqueous electrolyte.
The upper limit of the content of the cyclic carbonate compound (III) is preferably 10.0% by mass, more preferably 5.0% by mass, and still more preferably 3.0% by mass, relative to the total amount of the non-aqueous electrolyte. . When the upper limit of the content of the cyclic carbonate compound (III) is within the above range, it is possible to suppress an increase in the thickness of the SEI film while suppressing the decomposition of the non-aqueous solvent on the positive electrode or the negative electrode. . As a result, the properties of the electrochemical device after high temperature storage are improved.
The lower limit of the content of the cyclic carbonate compound (III) is preferably 0.10% by mass, more preferably 0.20% by mass, and still more preferably 0.30% by mass, relative to the total amount of the non-aqueous electrolyte. . When the lower limit of the content of the cyclic carbonate compound (III) is within the above range, an SEI film having a thickness capable of suppressing decomposition of the non-aqueous solvent in the non-aqueous electrolyte is formed. As a result, the properties of the electrochemical device after high temperature storage are improved.

(Lithium fluorophosphate compound (IV))
The lithium fluorophosphate compound (IV) is at least one selected from the group consisting of lithium monofluorophosphate and lithium difluorophosphate.
Lithium difluorophosphate is represented by the following formula (IV-1), and lithium monofluorophosphate is represented by the following formula (IV-2).

In addition to the nitrile compound (I), the non-aqueous electrolyte further contains the lithium fluorophosphate compound (IV). decrease and increase in DC resistance are further suppressed.

The non-aqueous electrolyte may contain only one of lithium monofluorophosphate and lithium difluorophosphate, or may contain lithium monofluorophosphate and lithium difluorophosphate.

When the non-aqueous electrolyte contains the lithium fluorophosphate compound (IV), the content of the lithium fluorophosphate compound (IV) is preferably within the following range.
The content of the lithium fluorophosphate compound (IV) is preferably 0.001% by mass to 5% by mass with respect to the total amount of the non-aqueous electrolyte.
The upper limit of the content of the lithium fluorophosphate compound (IV) is preferably 5% by mass, more preferably 3% by mass, and still more preferably 2% by mass relative to the total amount of the non-aqueous electrolyte. When the upper limit of the content of the lithium fluorophosphate compound (IV) is within the above range, the solubility of the lithium fluorophosphate compound (IV) in non-aqueous solvents can be ensured.
The lower limit of the content of the lithium fluorophosphate compound (IV) is preferably 0.001% by mass, more preferably 0.01% by mass, and still more preferably 0.1% by mass, relative to the total amount of the non-aqueous electrolyte. is. If the lower limit of the content of the lithium fluorophosphate compound (IV) is within the above range, the DC resistance of the electrochemical device can be further lowered.

(Cyclic dicarbonyl compound (V))
A cyclic dicarbonyl compound (V) is represented by the following formula (V).

In formula (V), M represents an alkali metal, b is an integer of 1-3, m is an integer of 1-4, n is an integer of 0-8, and q represents 0 or 1. R ⁵¹ is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a heteroatom, and when q is 1 and m is 2 to 4, each of m R ⁵¹ may be bonded.), and R ⁵² is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups are , the structure may contain a substituent or a heteroatom, and when n is 2 to 8, each of the n R ⁵² may combine to form a ring.), and Q ¹ and ^Q2 each independently represent an oxygen atom or a carbon atom.

The non-aqueous electrolyte further contains the cyclic dicarbonyl compound (V) in addition to the nitrile compound (I), so that the capacity of the electrochemical device decreases and the DC resistance decreases even in charge-discharge cycles after high-temperature storage. Increases are more restrained.
This effect is presumed to be due to the following reasons.
Since the non-aqueous electrolyte contains the cyclic dicarbonyl compound (V) in addition to the nitrile compound (I), the SEI membrane contains therein the above-described reaction products and the like, as well as the cyclic dicarbonyl compound ( V). This facilitates formation of a thermally and chemically stable polymer structure. Therefore, elution of components of the SEI film, deterioration of the SEI film, and the like, which impair the durability of the SEI film, are less likely to occur at high temperatures. As a result, the decrease in capacity and the increase in direct current resistance of the electrochemical device are further suppressed even in charge-discharge cycles after long-term storage in a high-temperature environment.

M is an alkali metal. Alkali metals include lithium, sodium, potassium and the like. Among them, M is preferably lithium.
b represents the valence of the anion and the number of cations. b is an integer of 1 to 3, preferably 1; When b is 3 or less, the salt of the anion compound is easily dissolved in the mixed organic solvent.
Each of m and n is a value related to the number of ligands. Each of m and n depends on the type of M. m is an integer of 1-4. n is an integer from 0 to 8;
q represents 0 or 1; When q is 0, the chelate ring is a five-membered ring, and when q is 1, the chelate ring is a six-membered ring.
R ⁵¹ represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms. These alkylene groups, halogenated alkylene groups, arylene groups or halogenated arylene groups may contain substituents and heteroatoms in their structures. Specifically, these groups may contain substituents instead of hydrogen atoms. Examples of substituents include halogen atoms, chain or cyclic alkyl groups, aryl groups, alkenyl groups, alkoxy groups, aryloxy groups, sulfonyl groups, amino groups, cyano groups, carbonyl groups, acyl groups, amide groups, or hydroxyl groups. be done. A structure in which a nitrogen atom, a sulfur atom, or an oxygen atom is introduced instead of the carbon atom of these groups may also be used. When q is 1 and m is 2 to 4, each of m R ⁵¹ may be bonded. Examples of such ligands include ethylenediaminetetraacetic acid.
R ⁵² represents a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms. Similar to R ⁵¹ , these alkyl groups, halogenated alkyl groups, aryl groups or halogenated aryl groups may contain substituents and heteroatoms in their structures, and when n is 2 to 8, n R ⁵² of may be combined to form a ring. R ⁵² is preferably an electron-withdrawing group, particularly preferably a fluorine atom.
Q ¹ and Q ² each independently represent an oxygen atom (O) or a carbon atom (C). That is, the ligand will be attached to Y through these heteroatoms.

Specific examples of the cyclic dicarbonyl compound (V) include compounds represented by the following formula (V-1) or (V-2). A compound represented by the formula (V-1) is referred to as a "cyclic dicarbonyl compound (V-1)".

The non-aqueous electrolyte may contain only one type of cyclic dicarbonyl compound (V), or may contain two or more types.

When the non-aqueous electrolyte contains the cyclic dicarbonyl compound (V), the content of the cyclic dicarbonyl compound (V) is preferably within the following range.
The content of the cyclic dicarbonyl compound (V) is preferably 0.01% by mass to 5.0% by mass with respect to the total amount of the non-aqueous electrolyte.
The upper limit of the content of the cyclic dicarbonyl compound (V) is preferably 10% by mass, more preferably 5.0% by mass, still more preferably 3.0% by mass, and particularly preferably 2.0% by mass. If the upper limit of the content of the cyclic dicarbonyl compound (V) is within the above range, the electrochemical device can operate without the SEI film impairing the conductivity of lithium cations. Furthermore, the cell characteristics of the electrochemical device are improved as the SEI film contains the cyclic dicarbonyl structure.
The lower limit of the content of the cyclic dicarbonyl compound (V) is preferably 0.01% by mass, more preferably 0.05% by mass, and still more preferably 0.10% by mass, relative to the total amount of the non-aqueous electrolyte. . When the lower limit of the content of the cyclic dicarbonyl compound (V) is within the above range, the SEI film contains a sufficient amount of structures mainly composed of cyclic dicarbonyl. This facilitates the formation of thermally and chemically stable inorganic salts or polymeric structures. Therefore, at high temperatures, elution of components of the SEI film and deterioration of the SEI film, which impair the durability of the SEI film, are less likely to occur. As a result, the durability of the SEI film and the high temperature post-storage properties of the electrochemical device are improved.

<Other ingredients>
The non-aqueous electrolyte may contain other components as needed.
Other components include acid anhydrides and the like.

[Electrochemical device precursor]
Next, electrochemical device precursors according to embodiments of the present disclosure will be described.

The electrochemical device precursor according to this embodiment includes a case, a positive electrode, a negative electrode, a separator, and an electrolytic solution. The case accommodates a positive electrode, a negative electrode, a separator, and an electrolytic solution. The positive electrode is capable of intercalating and deintercalating lithium ions. The negative electrode is capable of intercalating and deintercalating lithium ions. The separator separates the positive electrode and the negative electrode. The electrolytic solution is the non-aqueous electrolytic solution according to this embodiment.

An electrochemical device precursor indicates an electrochemical device before being subjected to charging and discharging. That is, in the electrochemical device precursor, the negative electrode does not contain an SEI film and the positive electrode does not contain an SEI film.

<Case>
The shape and the like of the case are not particularly limited, and are appropriately selected according to the use of the electrochemical device precursor according to the present embodiment. Examples of the case include a case including a laminate film, a case including a battery can and a battery can lid, and the like.

<Positive electrode>
The positive electrode preferably contains at least one positive electrode active material. The positive electrode active material is capable of intercalating and deintercalating lithium ions.

The positive electrode according to this embodiment includes a positive electrode current collector and a positive electrode mixture layer. The positive electrode mixture layer is provided on at least part of the surface of the positive electrode current collector.

Examples of materials for the positive electrode current collector include metals and alloys. Specifically, examples of materials for the positive electrode current collector include aluminum, nickel, stainless steel (SUS), and copper. Among them, the material of the positive electrode current collector is preferably aluminum from the viewpoint of the balance between high conductivity and cost. Here, "aluminum" means pure aluminum or an aluminum alloy. Aluminum foil is preferable as the positive electrode current collector. The material of the aluminum foil is not particularly limited, and examples thereof include A1085 material and A3003 material.

The positive electrode mixture layer contains a positive electrode active material and a binder.

The positive electrode active material is not particularly limited as long as it is capable of intercalating and deintercalating lithium ions, and can be appropriately adjusted according to the application of the electrochemical device precursor.

Examples of positive electrode active materials include first oxides and second oxides.
The first oxide contains lithium (Li) and nickel (Ni) as constituent metal elements.
The second oxide contains Li, Ni, and at least one of metal elements other than Li and Ni as constituent metal elements. Examples of metal elements other than Li and Ni include transition metal elements and typical metal elements. The second oxide preferably contains a metal element other than Li and Ni in a proportion equal to or lower than that of Ni in terms of the number of atoms. Metal elements other than Li and Ni are, for example, Co, Mn, Al, Cr, Fe, V, Mg, Ca, Na, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La and Ce. These positive electrode active materials may be used singly or in combination.

The positive electrode active material preferably contains a lithium-containing composite oxide (hereinafter sometimes referred to as "NCM") represented by the following formula (X). The lithium-containing composite oxide (X) has advantages of high energy density per unit volume and excellent thermal stability.

_{LiNiaCobMncO2} _... _Formula ₍ X)

In formula (X), a, b, and c are each independently greater than 0 and less than 1, and the sum of a, b, and c is 0.99 or more and 1.00 or less.

_Specific _examples _of _NCM _include _{LiNi0.33Co0.33Mn0.33O2} _, _{LiNi0.5Co0.3Mn0.2O2} _, _{LiNi0.5Co0.2Mn0.3O} _{_} ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ and the like.

The positive electrode active material may contain a lithium-containing composite oxide (hereinafter sometimes referred to as "NCA") represented by the following formula (Y).

_LitNi1 _-xyCoxAlyO2 _... _formula ( _Y )

In formula (Y), t is 0.95 or more and 1.15 or less, x is 0 or more and 0.3 or less, y is 0.1 or more and 0.2 or less, and x and y The sum is less than 0.5.

Specific examples of NCA include LiNi _0.8 Co _0.15 Al _0.05 O ₂ and the like.

When the positive electrode in the electrochemical device precursor according to the present embodiment includes a positive electrode current collector and a positive electrode mixture layer containing a positive electrode active material and a binder, the content of the positive electrode active material in the positive electrode mixture layer is preferably 10% by mass, more preferably 30% by mass, even more preferably 50% by mass, particularly preferably 70% by mass, relative to the total amount of the positive electrode mixture layer.
The upper limit of the content of the positive electrode active material in the positive electrode mixture layer is preferably 99.9% by mass, more preferably 99% by mass, relative to the total amount of the positive electrode mixture layer.

Binders include, for example, polyvinyl acetate, polymethyl methacrylate, nitrocellulose, fluororesin, and rubber particles.
Examples of fluororesins include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), vinylidene fluoride-hexafluoropropylene copolymer, and the like.
Examples of rubber particles include styrene-butadiene rubber particles and acrylonitrile rubber particles.
Among these, from the viewpoint of improving the oxidation resistance of the positive electrode mixture layer, the binder is preferably a fluororesin. A binder can be used individually by 1 type, and can be used in combination of 2 or more types as needed.

The content of the binder in the positive electrode mixture layer is preferably based on the total amount of the positive electrode mixture layer from the viewpoint of compatibility between the physical properties of the positive electrode mixture layer (e.g., electrolyte permeability, peel strength, etc.) and battery performance. is 0.1% by mass or more and 4% by mass or less. When the content of the binder is 0.1% by mass or more, the adhesiveness of the positive electrode mixture layer to the positive electrode current collector and the binding property between the positive electrode active materials are further improved. When the content of the binder is 4% by mass or less, the amount of the positive electrode active material in the positive electrode mixture layer can be increased, thereby further improving the capacity.

The positive electrode mixture layer according to this embodiment preferably contains a conductive aid.

A known conductive aid can be used as the conductive aid. A conductive carbon material is preferable as the known conductive aid. Carbon materials having conductivity include graphite, carbon black, conductive carbon fiber, fullerene, and the like. These can be used alone or in combination of two or more. Examples of conductive carbon fibers include carbon nanotubes, carbon nanofibers, and carbon fibers. Examples of graphite include artificial graphite and natural graphite. Examples of natural graphite include flaky graphite, massive graphite, earthy graphite, and the like.

The material of the conductive aid may be a commercially available product. Examples of commercial products of carbon black include Toka Black #4300, #4400, #4500, #5500 (manufactured by Tokai Carbon Co., Ltd., Furnace Black), Printex L, etc. (manufactured by Degussa Co., Ltd., Furnace Black), Raven7000, 5750. , 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA, Conductex 975 ULTRA, etc., PUREBLACK 100, 115, 205, etc. (manufactured by Columbian, furnace black), # 2350, # 2400B, # 2600B, # 30050B, # 3030 B, #3230B, # 3350B, # 3400B, # 5400B (manufactured by Mitsubishi Chemical, Fahnes Black), MONARCH1400, 1300, 900, VULCANXC -72R, BlackPealLS2000, LITX -50, LITX -200, etc. Nes Black), ENSACO250G, ENSACO260G , Ensaco 350G, Super-P (manufactured by TIMCAL), Ketjenblack EC-300J, EC-600JD (manufactured by Akzo), Denka black, Denka black HS-100, FX-35 (manufactured by Denka, acetylene black), etc. mentioned.

The positive electrode mixture layer according to this embodiment may contain other components. Other components include thickeners, surfactants, dispersants, wetting agents, antifoaming agents and the like.

<Negative Electrode>
The negative electrode contains at least one negative electrode active material. The negative electrode active material is capable of intercalating and deintercalating lithium ions.

The negative electrode according to this embodiment more preferably includes a negative electrode current collector and a negative electrode mixture layer. The negative electrode mixture layer is provided on at least part of the surface of the negative electrode current collector.

The material of the negative electrode current collector is not particularly limited and can be arbitrarily known, and examples thereof include metals and alloys. Specifically, examples of materials for the negative electrode current collector include aluminum, nickel, stainless steel (SUS), nickel-plated steel, and copper. Among them, copper is preferable as the material for the negative electrode current collector from the viewpoint of workability. A copper foil is preferable as the negative electrode current collector.

The negative electrode mixture layer according to this embodiment contains a negative electrode active material and a binder.

The negative electrode active material is not particularly limited as long as it can absorb and release lithium ions. The negative electrode active material is, for example, a lithium metal, a lithium-containing alloy, a metal or alloy that can be alloyed with lithium, an oxide that can be doped and dedoped with lithium ions, a transition material that can be doped and dedoped with lithium ions. It is preferably at least one selected from the group consisting of metal nitrides and carbon materials capable of doping and dedoping lithium ions. Among these, the negative electrode active material is preferably a carbon material capable of doping and dedoping lithium ions (hereinafter referred to as “carbon material”).

Examples of carbon materials include carbon black, activated carbon, graphite materials, and amorphous carbon materials. These carbon materials may be used singly or in combination of two or more. The form of the carbon material is not particularly limited, and examples thereof include fibrous, spherical, and flaky forms. The particle size of the carbon material is not particularly limited, and is preferably 5 μm or more and 50 μm or less, more preferably 20 μm or more and 30 μm or less.
Examples of amorphous carbon materials include hard carbon, coke, mesocarbon microbeads (MCMB) fired at 1500° C. or lower, and mesophase pitch carbon fibers (MCF).
Graphite materials include natural graphite and artificial graphite. Artificial graphite includes graphitized MCMB, graphitized MCF, and the like. The graphite material may contain boron. The graphite material may be coated with metal or amorphous carbon. Gold, platinum, silver, copper, tin and the like can be used as the material of the metal that coats the graphite material. The graphite material may be a mixture of amorphous carbon and graphite.

The negative electrode mixture layer according to this embodiment preferably contains a conductive aid. Examples of the conductive aid include conductive aids similar to the conductive aids exemplified as the conductive aid that can be contained in the positive electrode mixture layer.

The negative electrode mixture layer according to the present embodiment may contain other components in addition to the components described above. Other components include thickeners, surfactants, dispersants, wetting agents, antifoaming agents and the like.

<Separator>
Examples of separators include porous resin flat plates. Examples of the material of the porous resin flat plate include resin, non-woven fabric containing this resin, and the like. Examples of resins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyester, cellulose, and polyamide.

Among them, the separator is preferably a porous resin sheet having a single-layer or multi-layer structure. The material of the porous resin sheet is mainly composed of one or more polyolefin resins. The thickness of the separator is preferably 5 μm or more and 30 μm or less. A separator is preferably placed between the positive and negative electrodes.

[An example of an electrochemical device precursor]
An example of an electrochemical device precursor 1 according to an embodiment of the present disclosure will be specifically described with reference to FIG. FIG. 1 is a cross-sectional view of an electrochemical device precursor 1 according to an embodiment of the present disclosure.

The electrochemical device precursor 1 is of laminated type. As shown in FIG. 1 , the electrochemical device precursor 1 includes a battery element 10 , a positive electrode lead 21 , a negative electrode lead 22 and an outer package 30 . The battery element 10 is enclosed inside the exterior body 30 . The exterior body 30 is made of a laminate film. A positive electrode lead 21 and a negative electrode lead 22 are attached to the battery element 10 . Each of the positive electrode lead 21 and the negative electrode lead 22 is led out in opposite directions from the inside of the exterior body 30 toward the outside.

As shown in FIG. 1, the battery element 10 according to this embodiment is formed by laminating a positive electrode 11, a separator 13, and a negative electrode 12. The positive electrode 11 is formed by forming positive electrode mixture layers 11B on both main surfaces of a positive electrode current collector 11A. The negative electrode 12 is formed by forming negative electrode mixture layers 12B on both main surfaces of a negative electrode current collector 12A. A positive electrode mixture layer 11B formed on one main surface of the positive electrode current collector 11A of the positive electrode 11 and a negative electrode mixture layer 11B formed on one main surface of the negative electrode current collector 12A of the negative electrode 12 adjacent to the positive electrode 11. It faces the material layer 12B with the separator 13 interposed therebetween.

A non-aqueous electrolytic solution according to the present embodiment is injected into the interior of the exterior body 30 of the electrochemical device precursor 1 . The non-aqueous electrolyte according to this embodiment permeates the positive electrode mixture layer 11B, the separator 13, and the negative electrode mixture layer 12B. In the electrochemical device precursor 1, one unit cell layer 14 is formed by the adjacent positive electrode mixture layer 11B, separator 13, and negative electrode mixture layer 12B. The positive electrode 11 has a positive electrode mixture layer 11B formed on one main surface of a positive electrode current collector 11A, and the negative electrode 12 has a negative electrode mixture layer 12B formed on one main surface of a negative electrode current collector 12A. may be formed.

Although the electrochemical device precursor 1 is of a laminated type in the present embodiment, the present disclosure is not limited to this, and the electrochemical device precursor 1 may be of a wound type, for example. The wound type is formed by stacking a positive electrode, a separator, a negative electrode, and a separator in this order and winding them in layers. A wound type includes a cylindrical shape or a square shape.

In the present embodiment, as shown in FIG. 1, the direction in which each of the positive electrode lead 21 and the negative electrode lead 22 protrudes from the interior of the exterior body 30 toward the outside is the opposite direction to the exterior body 30. The disclosure is not so limited. For example, the direction in which each of the positive electrode lead and the negative electrode lead protrudes from the interior of the exterior body 30 toward the exterior may be the same direction with respect to the exterior body 30 .

As an example of an electrochemical device according to an embodiment of the present disclosure described below, on each surface of the positive electrode mixture layer 11B and the negative electrode mixture layer 12B in the electrochemical device precursor 1, Examples include an electrochemical device in which an SEI film is formed by charging and discharging.

[Electrochemical device]
Next, electrochemical devices according to embodiments of the present disclosure will be described.

An electrochemical device according to this embodiment is obtained by charging and discharging an electrochemical device precursor.
Specifically, the electrochemical device according to this embodiment includes a case, a positive electrode, a negative electrode, a separator, and an electrolytic solution. A positive electrode, a negative electrode, a separator, and an electrolytic solution are housed in a case. The positive electrode is capable of intercalating and deintercalating lithium ions. The negative electrode is capable of intercalating and deintercalating lithium ions. The electrolytic solution is the non-aqueous electrolytic solution according to this embodiment. The negative electrode includes an SEI film. The positive electrode includes an SEI film.

The electrochemical device according to this embodiment differs from the electrochemical device precursor according to this embodiment mainly in the first point that the negative electrode includes the SEI film and the second point that the positive electrode includes the SEI film. That is, the electrochemical device according to this embodiment is the same as the electrochemical device precursor according to this embodiment except for the first and second points. Therefore, the description of the constituent members of the electrochemical device of this embodiment other than the first and second points will be omitted below.

Regarding the first point, "the negative electrode includes an SEI film" includes a first negative electrode type and a second negative electrode type when the negative electrode includes a negative electrode current collector and a negative electrode mixture layer. The first negative electrode form indicates a form in which an SEI film is formed on at least a portion of the surface of the negative electrode mixture layer. The second negative electrode form indicates a form in which an SEI film is formed on the surface of the negative electrode active material, which is a constituent material of the negative electrode mixture layer.

Regarding the second point, "the positive electrode includes an SEI film" includes the first positive electrode configuration and the second positive electrode configuration when the positive electrode includes a positive current collector and a positive electrode mixture layer. The first positive electrode form indicates a form in which an SEI film is formed on at least a portion of the surface of the positive electrode mixture layer. The second positive electrode form indicates a form in which an SEI film is formed on the surface of the positive electrode active material, which is the constituent material of the positive electrode mixture layer.

The SEI membrane contains, for example, at least one selected from the group consisting of a decomposition product of nitrile compound (I), a reaction product of nitrile compound (I) and electrolyte, and a decomposition product of the reaction product.

The component of the SEI film of the positive electrode and the component of the SEI film of the negative electrode may be the same or different. The thickness of the SEI film of the positive electrode and the thickness of the SEI film of the negative electrode may be the same or different.

[Method for producing electrochemical device precursor]
Next, a method for manufacturing an electrochemical device precursor according to an embodiment of the present disclosure will be described.

The method for manufacturing an electrochemical device precursor according to this embodiment includes a first preparation process, a second preparation process, a third preparation process, a housing process, and an injection process. The accommodation process and the injection process are performed in this order. Each of the first preparation process, the second preparation process, and the third preparation process is performed before the accommodation process.

In the first preparation step, a positive electrode is prepared.
Examples of the method for preparing the positive electrode include a method of applying a positive electrode mixture slurry to the surface of the positive electrode current collector and drying the slurry. The positive electrode mixture slurry contains a positive electrode active material and a binder.
An organic solvent is preferable as the solvent contained in the positive electrode mixture slurry. Organic solvents include N-methyl-2-pyrrolidone (NMP) and the like.
The method of applying the positive electrode mixture slurry is not particularly limited, and examples thereof include slot die coating, slide coating, curtain coating, gravure coating and the like. The method for drying the positive electrode mixture slurry is not particularly limited, and includes drying with warm air, hot air, or low humidity air; vacuum drying; drying with infrared (for example, far-infrared) irradiation; and the like. The drying time is not particularly limited, and is preferably from 1 minute to 30 minutes. The drying temperature is not particularly limited, and is preferably 40°C or higher and 80°C or lower.
It is preferable that the positive electrode current collector is coated with the positive electrode mixture slurry and the dried product is subjected to a pressure treatment. This reduces the porosity of the positive electrode active material layer. Examples of the method of pressure treatment include die pressing and roll pressing.

A negative electrode is prepared in a 2nd preparation process.
As a method of preparing the negative electrode, for example, a method of applying a negative electrode mixture slurry to the surface of the negative electrode current collector and drying the slurry can be used. The negative electrode mixture slurry contains a negative electrode active material and a binder.
Examples of the solvent contained in the negative electrode mixture slurry include water and a liquid medium compatible with water. When the solvent contained in the negative electrode mixture slurry contains a liquid medium that is compatible with water, it is possible to improve the coatability onto the negative electrode current collector. Liquid media compatible with water include alcohols, glycols, cellosolves, aminoalcohols, amines, ketones, carboxylic acid amides, phosphoric acid amides, sulfoxides, carboxylic acid esters, and phosphate esters. , ethers, nitriles and the like.
The application method, drying method, and pressure treatment of the negative electrode mixture slurry include the same methods as those exemplified as the application method, drying method, and pressure treatment of the positive electrode mixture slurry.

In the third preparation step, a non-aqueous electrolyte is prepared.
As a method for preparing the non-aqueous electrolyte, for example, a step of dissolving the electrolyte in a non-aqueous solvent to obtain a solution, and adding and mixing the nitrile compound (I) to the obtained solution to obtain a non-aqueous and obtaining an electrolytic solution.

In the housing step, the positive electrode, the negative electrode, and the separator are housed in the case.
For example, in the housing step, a battery element is produced with a positive electrode, a negative electrode, and a separator. Next, the positive current collector of the positive electrode and the positive electrode lead are electrically connected, and the negative electrode current collector of the negative electrode and the negative electrode lead are electrically connected. Next, the battery element is housed in the case and fixed.
A method for electrically connecting the positive electrode current collector and the positive electrode lead is not particularly limited, and examples thereof include ultrasonic welding and resistance welding. A method for electrically connecting the negative electrode current collector and the negative electrode lead is not particularly limited, and examples thereof include ultrasonic welding and resistance welding.

Hereinafter, the state in which the positive electrode, the negative electrode, and the separator are accommodated in the case will be referred to as the "assembly".

In the injection step, the non-aqueous electrolyte according to this embodiment is injected into the assembly. This allows the non-aqueous electrolyte to permeate the positive electrode mixture layer, the separator, and the negative electrode mixture layer. As a result, an electrochemical device precursor is obtained.

[Method for producing electrochemical device]
Next, a method for manufacturing an electrochemical device according to an embodiment of the present disclosure will be described.

The method for manufacturing an electrochemical device according to this embodiment includes a fourth preparation step and an aging step. A 4th preparation process and an aging process are performed in this order.

In the fourth preparation step, an electrochemical device precursor is prepared. The method of preparing the electrochemical device precursor is the same as the method described in the method of manufacturing the electrochemical device precursor.

In the aging process, the electrochemical device precursor is charged and discharged. An SEI film is thus formed. That is, an electrochemical device is obtained.

Hereinafter, the process of charging and discharging the electrochemical device precursor is referred to as "aging process".

The aging treatment may be performed in an environment of 25°C or higher and 70°C or lower.
The aging process may include a first charge phase, a first hold phase, a second charge phase, a second hold phase, and a charge/discharge phase.

In the first charging phase, the electrochemical device precursor is charged in an environment of 25°C or higher and 70°C or lower. In the first holding phase, the electrochemical device precursor after the first charging phase is held in an environment of 25°C or higher and 70°C or lower. In the second charging phase, the electrochemical device precursor after the first holding phase is charged in an environment of 25°C or higher and 70°C or lower. In the second holding phase, the electrochemical device precursor after the second charging phase is held in an environment of 25°C or higher and 70°C or lower. In the charging/discharging phase, the electrochemical device precursor after the second holding phase is subjected to a combination of charging and discharging one or more times under an environment of 25° C. or higher and 70° C. or lower.

Even if the electrochemical device obtained by the method for manufacturing an electrochemical device according to the present embodiment is stored for a long time in a high-temperature environment, the effect of suppressing the decrease in capacity of the electrochemical device and the increase in direct current resistance is more effective. demonstrated.

Hereinafter, embodiments according to the present disclosure will be described in detail with reference to Examples. Note that the present disclosure is not limited to the description of these examples.

[Example 1]
A non-aqueous electrolyte was obtained as follows.

(Preparation of non-aqueous electrolyte)
Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) were mixed at EC:DMC:EMC=30:35:35 (volume ratio). As a result, a mixed solvent (non-aqueous solvent) was obtained as the non-aqueous solvent.
LiPF ₆ (electrolyte) was dissolved in the obtained mixed solvent so that the concentration in the finally obtained non-aqueous electrolyte solution was 1 mol/liter to obtain an electrolyte solution.

Hereafter, the obtained electrolytic solution is referred to as the "basic electrolytic solution".

The content of the nitrile compound (I-1) and the cyclic sulfone compound (II-1) as additives with respect to the total amount of the finally obtained non-aqueous electrolyte is the content (% by mass) shown in Table 1. was added to the basic electrolytic solution so that A non-aqueous electrolyte was thus obtained.
Nitrile compound (I-1) is represented by the following formula (I-1). The cyclic sulfone compound (II-1) is represented by the following formula (II-1)

<Preparation of electrochemical device precursor>
An aluminum laminate type battery as an electrochemical device precursor was produced in the following manner.

(First preparation step)
A positive electrode was prepared as follows.
Li (Ni _0.5 Co _0.2 Mn _0.3 O ₂ ) (94% by mass) as a positive electrode active material, carbon black (3% by mass) as a conductive aid, and polyvinylidene fluoride (PVDF) as a binder (3% by weight) was added to obtain a mixture. The resulting mixture was dispersed in an N-methylpyrrolidone solvent to obtain a positive electrode mixture slurry.
A 20 μm thick aluminum foil was prepared as a positive electrode current collector.
The resulting positive electrode mixture slurry was applied onto an aluminum foil (positive electrode current collector), dried, and then rolled with a press to obtain a positive electrode raw sheet. This positive electrode material has a region where a positive electrode active material layer (hereinafter referred to as a “positive electrode material layer”) is formed and a region where a positive electrode material layer is not formed (hereinafter referred to as a “non-tab adhesive layer”). (referred to as "coating part"). The uncoated portion for tab bonding is an uncoated portion that serves as a margin.
The obtained positive electrode raw fabric was slit to obtain a positive electrode. The positive electrode has a positive electrode mixture layer and an uncoated portion for tab adhesion. The size of the positive electrode mixture layer was 29 mm wide and 40 mm long. The size of the uncoated portion for tab bonding was 5 mm wide and 11 mm long.

(Second preparation step)
A negative electrode was prepared as follows.
Graphite (96% by mass) as a negative electrode active material, carbon black (1% by mass) as a conductive agent, 1% by mass of solid content of carboxymethylcellulose sodium dispersed in pure water as a thickener, and pure Styrene-butadiene rubber (SBR) dispersed in water was mixed at a solid content of 2% by mass to obtain a negative electrode mixture slurry.
A copper foil having a thickness of 10 μm was prepared as a negative electrode current collector.
The resulting negative electrode mixture slurry was applied onto a copper foil (negative electrode current collector), dried, and then rolled with a pressing machine to obtain a negative electrode raw sheet. This negative electrode raw fabric includes a region where a negative electrode active material mixture layer (hereinafter referred to as a “negative electrode mixture layer”) is formed and a region where a negative electrode mixture layer is not formed (hereinafter referred to as a “tab adhesion blank”). (referred to as "coating part"). The uncoated portion for tab bonding is an uncoated portion that serves as a margin.
The obtained negative electrode raw fabric was slit to obtain a negative electrode. The negative electrode has a negative electrode mixture layer and an uncoated portion for tab adhesion. The size of the negative electrode mixture layer was 30 mm wide and 41 mm long. The size of the uncoated portion for tab bonding was 5 mm wide and 11 mm long.

(Third preparation step)
A non-aqueous electrolyte solution obtained in the production of the non-aqueous electrolyte solution described above was prepared.

(Accommodation process)
A porous polypropylene film was prepared as a separator.
A positive electrode, a negative electrode, and a separator were laminated in such a manner that the coated surface of the negative electrode was in contact with the separator and the coated surface of the positive electrode was in contact with the separator to obtain a laminate. Next, an aluminum positive electrode tab (positive electrode lead) was bonded to the uncoated portion for tab bonding of the positive electrode of the obtained laminate by an ultrasonic bonding machine. A negative electrode tab (negative electrode lead) made of nickel was bonded to the uncoated portion for tab bonding of the negative electrode of the obtained laminate by an ultrasonic bonding machine. The laminated body in which the positive electrode tab and the negative electrode tab were joined was sandwiched between a pair of laminated films (cases) in which both sides of aluminum were coated with a resin layer, and then heat-sealed on three sides to obtain a laminate (assembly). At this time, the positive electrode tab and the negative electrode tab protruded from one of the three sealed sides of the laminate that was in contact with the unsealed opening.

(Injection process)
0.25 mL of the non-aqueous electrolytic solution obtained above was injected from the opening of the laminate to seal the opening of the laminate. As a result, an aluminum laminate type battery (electrochemical device precursor) was obtained.

[Examples 2 to 10, Comparative Examples 1 to 2]
Nitrile compound (I-1), cyclic sulfone compound (II-1), cyclic carbonate compound (III-1), lithium difluorophosphate, and cyclic dicarbonyl compound (V-1) as additives was added to the basic electrolytic solution so that the content relative to the total amount of the finally obtained non-aqueous electrolytic solution was the content (% by mass) shown in Table 1. In the same manner as in Example 1. , an aluminum laminate type battery (electrochemical device precursor) was obtained.
Incidentally, the nitrile compound (I-1) is represented by the following formula (I-1). The cyclic sulfone compound (II-1) is represented by the following formula (II-1). The cyclic carbonate compound (III-1) is represented by the following formula (III-1). Lithium difluorophosphate is represented by the following formula (IV-1). The cyclic dicarbonyl compound (V-1) is represented by the following formula (V-1).

〔Evaluation test〕
The obtained aluminum laminate type battery was subjected to the following aging treatment to obtain a first battery. The obtained first battery was subjected to the following initial charge/discharge treatment to obtain a second battery. The obtained second battery was subjected to the following DC resistance evaluation treatment to obtain a third battery. The obtained third battery was subjected to high-temperature storage treatment to obtain a fourth battery. The obtained fourth battery was subjected to the following late charge/discharge treatment to obtain a fifth battery.
Using the obtained first to fifth batteries, the resistance after high temperature storage and the capacity retention rate were each measured by the following measurement method. These measurement results are shown in Table 1.

<Aging treatment>
An aluminum laminate type battery (electrochemical device battery precursor) was subjected to the following aging treatment to obtain a first battery.
An aluminum laminate type battery (electrochemical device battery precursor) is charged at a temperature range of 25° C. to 70° C. with a final voltage of 1.5 V to 3.5 V, and then rested for 5 hours to 50 hours. rice field. Next, the battery precursor was charged in a temperature range of 25° C. to 70° C. with a final voltage range of 3.5 V to 4.2 V and held for 5 hours to 50 hours. Next, the battery precursor was charged to 4.2V and then discharged to 2.5V under a temperature range of 25°C to 70°C. Thus, a first battery was obtained.

<Initial charge/discharge treatment>
The first battery was subjected to the following initial charge/discharge treatment to obtain a second battery.
The first battery was held in a temperature environment of 25° C. for 12 hours. Next, the first battery was charged at a charge rate of 0.2C to 4.2V (SOC (State Of Charge) 100%) by constant current and constant voltage charge (0.2C-CCCV), then rested for 30 minutes, and then the discharge rate Constant current discharge (0.2C-CC) was performed at 0.2C to 2.5V. This was repeated for 3 cycles to stabilize the first battery. Then, constant current and constant voltage charge (0.5C-CCCV) to 4.2V at a charge rate of 0.2C, followed by resting for 30 minutes, and then constant current discharge (1C-CCV) to 2.5V at a discharge rate of 1C. ). Thus, a second battery was obtained.

<Treatment for DC resistance evaluation>
The second battery was subjected to the following DC resistance evaluation treatment to obtain a third battery.
The second battery was CCCV charged to 3.7 V at a charge rate of 0.2 C in a temperature environment of 25°C. “CCCV charging” means charging with a constant current constant voltage (Constant Current Constant Voltage).
Next, in a temperature environment of 25° C., CC10s discharge was performed at a discharge rate of 1C, and CC10s charge was performed at a charge rate of 1C. "CC10s discharge" means discharging for 10 seconds at a constant current (Constant Current). "CC10s charging" means charging for 10 seconds at a constant current (Constant Current).
Next, the second battery was subjected to CC10s discharge at a discharge rate of 2C and CC20s charge at a charge rate of 1C.
Next, the second battery was subjected to CC10s discharge at a discharge rate of 3C and CC30s charge at a charge rate of 1C.
Next, the second battery was discharged at a discharge rate of 4C for CC10s and charged at a charge rate of 1C for CC40s.
Next, the second battery was discharged at a discharge rate of 5C for CC10s and charged at a charge rate of 1C for CC50s. A third battery was thus obtained.

<High temperature storage treatment>
The third battery was subjected to the following high-temperature storage treatment to obtain a fourth battery.
The third battery was constant current charged to 4.2 V at a charge rate of 0.2 C in a temperature environment of 25°C. Next, the third battery in the charged state was allowed to stand in an atmosphere of 60° C. for 28 days. Thus, a fourth battery was obtained.

<Late charge/discharge treatment>
The fourth battery was subjected to the following late charge/discharge treatment to obtain a fifth battery.
The fourth battery was subjected to heat dissipation in a temperature environment of 25° C., first discharge, first charge, and second discharge. The first discharge indicates constant current discharge (1C-CC) to 2.5V at a discharge rate of 1C. The first charge indicates constant current constant voltage charge (0.2C-CCCV) up to 4.2V at a charge rate of 0.2C. The second discharge indicates constant current discharge (1C-CC) to 2.5V at a discharge rate of 1C. Thus, a fifth battery was obtained.

<Measurement method of resistance after high temperature storage>
As shown in the following formula (X1), the direct current internal resistance (DCIR) of the fifth battery of Comparative Example 1 is relative to the direct current resistance of the fifth battery of Examples 1 to 10 and Comparative Example 2. The value was taken as "resistance after high temperature storage [%]" (see Table 1).

Resistance after high-temperature storage [relative value; %] = (DC resistance of the fifth battery [Ω]/DC resistance of the fifth battery of Comparative Example 1 [Ω]) x 100 ... (X1)

DC resistance was measured by the following method. The fifth battery was subjected to the same DC resistance evaluation process as the DC resistance evaluation process described above.
Each voltage drop amount due to "CC10s discharge" at each discharge rate 1C to 5C (= voltage before discharge start - voltage at 10 seconds after discharge start) and each current value (that is, discharge rate 1C to 5C) The DC resistance (Ω) of the fifth battery was obtained based on each current value).

<Method for measuring capacity retention rate>
As shown in the following formula (X2), the relative value of the capacity retention rate of the fourth battery of Examples 1 to 10 and Comparative Example 2 with respect to the capacity retention rate of the fourth battery of Comparative Example 1 is expressed as "capacity maintenance rate [%]” (see Table 1).

Capacity retention rate [relative value; %] = (Capacity retention rate/Capacity retention rate of Comparative Example 1) x 100... (X2)

In the formula (X2), the capacity retention rate is the discharge capacity (mAh/g) of the fourth battery obtained when performing the second discharge in the above-described late charge-discharge treatment, and the first discharge capacity in the above-described initial charge-discharge treatment. It is divided by the discharge capacity (mAh/g) obtained at the last discharge of the battery.

The relative value of the discharge capacity of the fourth battery after the high-temperature storage test corresponds to the discharge capacity reduction rate (%) due to storage (hereinafter also simply referred to as "capacity reduction rate"). The reduction rate here is expressed as 100% when there is no increase or decrease, when it decreases as less than 100%, and when it increases as more than 100%.

The reason for focusing on the capacity retention rate is that while a large capacity value itself is an important performance factor in terms of battery performance, it is also extremely important to reduce capacity loss due to deterioration during storage. Because.

In Table 1, the item "Additive" indicates the content [% by mass] of each additive with respect to the total amount of the non-aqueous electrolyte. In Table 1, "-" means that the corresponding component is not contained. In Table 1, "EC+DMC+EMC" in [non-aqueous solvent] indicates a mixed solvent in which ethylene carbonate (EC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) are mixed.

The non-aqueous electrolytic solutions of Examples 1 to 10 contain nitrile compound (I), non-aqueous solvent, electrolyte, and compound (A). The content of the nitrile compound (I) was 0.5% by mass to 2.5% by mass and within the range of 0.01% by mass to 5% by mass with respect to the total amount of the non-aqueous electrolyte. Therefore, the electrochemical devices of Examples 1 to 10 had lower resistance after high-temperature storage and higher capacity retention than the electrochemical devices of Comparative Examples 1 and 2. That is, it was found that the non-aqueous electrolyte solutions of Examples 1 to 10 can suppress a decrease in capacity and an increase in DC resistance even when an electrochemical device is stored for a long period of time in a high-temperature environment.

The disclosure of Japanese Patent Application No. 2021-206277 filed on December 20, 2021 is incorporated herein by reference in its entirety.
All publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. incorporated herein by reference.

Claims

A non-aqueous electrolyte,
including a compound (I) represented by the following formula (I), a non-aqueous solvent, an electrolyte, and a compound (A),
The compound (A) is a group consisting of a compound (II) represented by the following formula (II), a compound (III) represented by the following formula (III), and lithium monofluorophosphate and lithium difluorophosphate. At least one selected from the group consisting of a compound (VI) that is at least one selected from and a compound (V) represented by the following formula (V),
A non-aqueous electrolytic solution in which the content of the compound (I) is 0.01% by mass to 5% by mass relative to the total amount of the non-aqueous electrolytic solution.
R 11 -X-R 12 -C≡N (I)
(In formula (I), X is -S (=O) 2 - (sulfone structure), -OS (=O) -O- (sulfite structure), or -OC (=O) - C (= O) -O- (oxalate structure),
R 11 represents a cyanoalkyl group having 2 to 5 carbon atoms, a 2-alkynyl group having 3 to 5 carbon atoms, or an alkyl group having 1 to 6 carbon atoms,
R 12 represents an alkylene group having 1 to 4 carbon atoms. )

[In formula (II), R 21 represents an oxygen atom, an alkylene group having 1 to 6 carbon atoms, an alkenylene group having 1 to 6 carbon atoms, or a vinylene group, and R 22 represents an alkylene group having 1 to 6 carbon atoms. , represents a group represented by the above formula (ii-1) or a group represented by the above formula (ii-2). * indicates the binding position. In formula (ii-2) above, R 23 represents a group represented by an alkyl group having 1 to 6 carbon atoms.
In formula (III), R31 and R32 are each independently a hydrogen atom, a methyl group, an ethyl group, or a propyl group.
In formula (V), M represents an alkali metal, b is an integer of 1-3, m is an integer of 1-4, n is an integer of 0-8, and q represents 0 or 1. R 51 is an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a halogenated arylene group having 6 to 20 carbon atoms (these groups are The structure may contain a substituent or a heteroatom, and when q is 1 and m is 2 to 4, each of m R 51 may be bonded.), and R 52 is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these groups are , the structure may contain a substituent or a heteroatom, and when n is 2 to 8, each of the n R 52 may combine to form a ring.), and Q 1 and Q2 each independently represent an oxygen atom or a carbon atom. ]
2. The nonaqueous electrolytic solution according to claim 1, wherein said X is -S(=O) 2 - (sulfone structure).
3. The nonaqueous electrolytic solution according to claim 1, wherein the compound (I) is a compound (I-1) represented by the following formula (I-1).
a case;
a positive electrode, a negative electrode, a separator, and an electrolytic solution housed in the case;
with
the positive electrode is a positive electrode capable of intercalating and deintercalating lithium ions;
the negative electrode is a negative electrode capable of intercalating and deintercalating lithium ions;
An electrochemical device precursor, wherein the electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 3.
5. The electrochemical device precursor according to claim 4, wherein the positive electrode contains a lithium-containing composite oxide represented by the following formula (X) as a positive electrode active material.
LiNiaCobMncO2 ... Formula ( X)
[In formula (X), a, b and c are each independently greater than 0 and less than 1, and the sum of a, b and c is 0.99 or more and 1.00 or less. ]
preparing an electrochemical device precursor according to claim 4 or claim 5;
and a step of charging and discharging the electrochemical device precursor.
An electrochemical device obtained by charging and discharging the electrochemical device precursor according to claim 4 or claim 5.