WO2012086602A1 - Nonaqueous electrolyte solution for secondary batteries, and secondary battery - Google Patents

Abstract

The purpose of the present invention is to provide: a nonaqueous electrolyte solution for secondary batteries, which is capable of achieving excellent low-temperature characteristics, while assuring other characteristics such as electrical conductivity; and a secondary battery which uses the nonaqueous electrolyte solution for secondary batteries. Specifically provided is a nonaqueous electrolyte solution for secondary batteries, which contains: a lithium salt; a specific fluorine-containing ether solvent; a glyme solvent such as monoglyme that contains two ether oxygen atoms; and another glyme solvent such as diglyme that contains 3-5 ether oxygen atoms. Also specifically provided is a secondary battery which uses the nonaqueous electrolyte solution for secondary batteries.

Description

Nonaqueous electrolyte for secondary battery and secondary battery

The present invention relates to a non-aqueous electrolyte for a secondary battery and a secondary battery.

As a solvent for a non-aqueous electrolyte for a secondary battery, in general, lithium salt is dissolved well to express high lithium ion conductivity, and from the point of having a wide potential window, ethylene carbonate, dimethyl carbonate, etc. These carbonate compounds have been widely used. However, non-aqueous electrolytes containing carbonate compounds tend to have a low flash point.

As a method for increasing the nonflammability (flame retardancy) of a non-aqueous electrolyte, a method of adding a fluorine-based solvent has been proposed. In order to improve the solubility of the electrolyte salt, the combined use of a cyclic non-fluorine carbonate and a chain non-fluorine ether has been proposed.

On the other hand, lithium salts such as CF ₃ SO ₂ N (Li) SO ₂ CF ₃ and FSO ₂ N (Li) SO ₂ F strongly interact with the etheric oxygen atom of the glyme-based solvent and have a stable 1: 1. Form a complex. From the results of thermal analysis and the like, it has been reported that the complex behaves as a single ionic species and does not ignite at all even when heated by a burner (Non-patent Documents 1 and 2). However, when the non-aqueous electrolyte containing the 1: 1 complex is evaluated, it is not suitable for practical use because of its high viscosity and low electrical conductivity.
Examples of including a complex of a lithium salt and a glyme solvent in the electrolyte include the following.
A nonaqueous electrolytic solution comprising a complex salt of LiBF ₄ and 1-ethoxy-2-methoxyethane (Patent Document 1).
A nonaqueous electrolytic solution containing LiPF ₆ , 1,2-dimethoxyethane or 1,2-diethoxyethane, a fluorinated monoether, and ethylene carbonate (Patent Document 2).
A nonaqueous electrolytic solution containing a lithium salt such as (CF ₃ SO ₂ ) ₂ NLi, tetraglyme, and optionally an organic solvent (Patent Document 3).
A non-aqueous electrolyte containing 1,2-dimethoxyethane together with a lithium salt, a fluorinated ether and a non-fluorinated carbonate (Patent Document 4).
A nonaqueous electrolytic solution containing a lithium salt, a hydrofluoroether, and a glyme solvent (Patent Document 5).

Japanese Unexamined Patent Publication No. 2005-126339 Japanese Unexamined Patent Publication No. 2010-238510 Japanese Unexamined Patent Publication No. 2009-245911 Japanese Unexamined Patent Publication No. 2008-218387 International Publication No. 2009/133899

However, when the present inventors evaluated the non-aqueous electrolytes described in Patent Documents 1 to 5, it was found that the conventional non-aqueous electrolytes did not have sufficient performance as electrolytes at low temperatures.

The present invention provides a non-aqueous electrolyte for a secondary battery capable of obtaining excellent low-temperature characteristics while ensuring other characteristics such as conductivity, and a secondary battery using the non-aqueous electrolyte for a secondary battery With the goal.

The present invention employs the following configuration in order to solve the above problems.
[1] A lithium salt, a fluorine-containing ether solvent selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), a compound represented by the following formula (3), and A nonaqueous electrolytic solution for a secondary battery comprising a compound represented by the following formula (4):

(Wherein R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, or 3 to 10 carbon atoms) A fluorinated cycloalkyl group, an alkyl group having 1 to 10 carbon atoms having one or more etheric oxygen atoms between carbon atoms and carbon atoms, or one or more etheric oxygen atoms between carbon atoms and carbon atoms And a fluorinated alkyl group having 1 to 10 carbon atoms, wherein one or both of R ¹ and R ² is a fluorinated alkyl group.
X is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 carbon atoms having one or more etheric oxygen atoms between carbon atoms and carbon atoms, or carbon A fluorinated alkylene group having 1 to 5 carbon atoms having one or more etheric oxygen atoms between atoms and carbon atoms.
Q ¹ represents a linear alkylene group having 1 to 4 carbon atoms, or one or more hydrogen atoms of the linear alkylene group are alkyl groups having 1 to 5 carbon atoms, or one or more carbon atoms between carbon atoms. And an alkyl group having 1 to 5 carbon atoms containing an etheric oxygen atom.
R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ⁴ .
m is an integer of 2-4.
Q ² is a linear alkylene group having 1 to 4 carbon atoms, or one or more of hydrogen atoms of the linear alkylene group is an alkyl group having 1 to 5 carbon atoms, or a carbon atom-carbon atom. And an alkyl group having 1 to 5 carbon atoms containing an etheric oxygen atom. Q ² may be the same group or different groups.
R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ⁵ and R ⁶ . )
[2] Formula (3) compounds represented by (molar amount: M _III) and the formula (4) compounds represented by (molar amount: M _IV) molar ratio (M _III / M _IV) is 10 The nonaqueous electrolytic solution for secondary battery according to [1], which is / 90 to 90/10.
[3] The non-aqueous electrolyte for a secondary battery according to [1] or [2], wherein the compound represented by the formula (3) is essentially a compound represented by the following formula (3A).

(However, in the formula, R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms, or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ^4. )
[4] The nonaqueous electrolysis for secondary battery according to any one of [1] to [3], wherein the compound represented by the formula (4) is essentially a compound represented by the following formula (4A): liquid.

(In the formula, m is an integer of 2 to 4. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms, or R ¹ and C ⁵ formed by linking R ⁵ and R ^6. 10 alkylene groups.)
[5] The compound represented by the formula (3) and the formula (4) with respect to the total number of moles of lithium atoms derived from the lithium salt (N _Li ) contained in the non-aqueous electrolyte for secondary batteries. The secondary according to any one of [1] to [4], wherein the ratio (N _O / N _Li ) of the total number of moles (N _O ) of etheric oxygen atoms derived from the represented compound is 1 to 6 Non-aqueous electrolyte for batteries.
[6] The lithium salt is LiPF ₆ , a compound represented by the following formula (5), FSO ₂ N (Li) SO ₂ F, CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₁ N or more selected from the group consisting of ₂ N (Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ , a compound represented by the following formula (6), a compound represented by the following formula (7), and LiBF ₄ The non-aqueous electrolyte for a secondary battery according to any one of [1] to [5].

(In the formula, k is an integer of 1 to 5.)
[7] The nonaqueous electrolytic solution according to any one of [1] to [6], which contains a surfactant.
[8] The compound represented by the above formula (1) is CF ₃ CH ₂ OCF ₂ CF ₂ H, CHF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H, CF ₃ CF ₂ CH ₂ OCF ₂ CHF ₂ , or CF _3. The secondary battery according to any one of [1] to [7], wherein one or more selected from the group consisting of CH ₂ OCF ₂ CHFCF ₃ and CHF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ is essential. Non-aqueous electrolyte for use.
[9] A compound having a ring structure composed of a carbon atom and an oxygen atom, the ring structure having a bond represented by —O—C (═O) —O—, and a carbon- The nonaqueous electrolytic solution for a secondary battery according to any one of [1] to [8], which contains the compound (8) having no carbon unsaturated bond.
[10] A compound having a ring structure composed of a carbon atom and an oxygen atom, the ring structure containing a bond represented by —O—C (═O) —O—, and carbon-carbon unsaturated in the molecule The non-aqueous electrolyte for secondary batteries according to any one of [1] to [9], which contains a compound (9) containing a bond.
[11] The non-aqueous electrolyte for a secondary battery according to any one of [1] to [10], which is used as an electrolyte for a lithium ion secondary battery.
[12] The material according to any one of [1] to [10], a material capable of inserting and extracting lithium ions, a negative electrode made of metallic lithium or a lithium alloy, a positive electrode made of a material capable of inserting and extracting lithium ions, and A secondary battery comprising a non-aqueous electrolyte for a secondary battery.

The non-aqueous electrolyte for a secondary battery of the present invention can provide excellent low temperature characteristics while ensuring other characteristics such as conductivity.
Moreover, if the secondary battery of this invention is used, the secondary battery which has the outstanding low temperature characteristic and other characteristics, such as an electrical conductivity, is practically sufficient.

In the present specification, unless otherwise specified, the compound represented by the formula (1) is referred to as a compound (1), and other formulas are also shown in the same manner.
<Non-aqueous electrolyte for secondary battery>
The non-aqueous electrolyte for secondary batteries of the present invention (hereinafter simply referred to as “non-aqueous electrolyte”) is a fluorine-containing ether selected from the group consisting of a lithium salt to be described later, compound (1) and compound (2). An electrolytic solution containing a solvent, a compound (3), and a compound (4). A non-aqueous electrolyte is an electrolyte that uses a solvent that does not substantially contain water. Even if water is included, the water content of the non-aqueous electrolyte has deteriorated in the performance of a secondary battery that uses the non-aqueous electrolyte. It is an electrolyte solution in an amount that is not possible. The amount of water that can be contained in the non-aqueous electrolyte is preferably 500 ppm by mass or less, more preferably 100 ppm by mass or less, and 50 ppm by mass or less with respect to the total mass of the electrolyte. Is particularly preferred. The lower limit of the moisture content is 0 mass ppm.

[Lithium salt]
Lithium salt is an electrolyte that dissociates in a non-aqueous electrolyte and supplies lithium ions. Examples of the lithium salt include LiPF ₆ , the following compound (5), FSO ₂ N (Li) SO ₂ F, CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N (Li) SO ₂ CF. ₂ CF _3, LiClO _4, the following compound (6), the following compound (7), and one or more is preferably selected from the group consisting of LiBF _4. The lithium _salt, LiPF _6, LiBF ₄ and the compound (5) at least one member selected from the group consisting of is more preferable.
Only one lithium salt may be used, or two or more lithium salts may be used in combination. The combination in the case of using 2 or more types of lithium salt together includes the combination shown in International Publication No. 2009/133899.
As the lithium salt, it is more preferable that LiPF ₆ is essential, and it is particularly preferable to use only LiPF ₆ .

However, k in the compound (5) is an integer of 1 to 5.
Examples of the compound (5) include the following compounds (5-1) to (5-4). The nonaqueous electrolytic solution of the present invention requires a compound (5-2) in which k is 2 when the compound (5) is used because a nonaqueous electrolytic solution having high conductivity is easily obtained. It is more preferable that the compound consists only of the compound (5-2) in which k is 2.

The content of the lithium salt in the non-aqueous electrolyte is not particularly limited, but is preferably 0.1 to 3.0 mol / L, particularly preferably 0.5 to 2.0 mol / L. If the content of the lithium salt is not less than the lower limit of the above range, a non-aqueous electrolyte with high conductivity is easily obtained. If the lithium salt content is not more than the upper limit of the above range, the lithium salt can be easily dissolved in the compounds (1) to (4) described later and the compound (8) used as necessary.

[Fluorine-containing ether solvent]
The fluorine-containing ether solvent selected from the group consisting of the following compound (1) and the following compound (2) is used as a solvent that imparts nonflammability to the nonaqueous electrolytic solution. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

In the formula (1), R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, or a carbon number A fluorinated cycloalkyl group having 3 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms having one or more etheric oxygen atoms between carbon atoms and carbon atoms, or one or more ethers between carbon atoms and carbon atoms A fluorinated alkyl group having 1 to 10 carbon atoms having a reactive oxygen atom, and one or both of R ¹ and R ² is a fluorinated alkyl group.
In the formula (2), X is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, or a carbon atom having 1 or more etheric oxygen atoms between carbon atoms. Or a fluorinated alkylene group having 1 to 5 carbon atoms having one or more etheric oxygen atoms between carbon atoms.

In the present specification, fluorination means that a part or all of hydrogen atoms bonded to a carbon atom is substituted with a fluorine atom. The fluorinated alkyl group is a group in which part or all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms. A hydrogen atom is present in a partially fluorinated group. Partial fluorination means that a part of hydrogen atoms bonded to a carbon atom is replaced with a fluorine atom.
In addition, as the alkyl group and the alkyl group having an etheric oxygen atom between carbon atoms, a group having a linear structure, a branched structure, or a partial cyclic structure (for example, a cycloalkylalkyl group), respectively. Is mentioned.

One or both of R ¹ and R ² in the compound (1) is a fluorinated alkyl group. When one or both of R ¹ and R ² are fluorinated alkyl groups, the solubility of the lithium salt in the non-aqueous electrolyte and the flame retardancy are improved. R ¹ and R ² in the compound (1) may be the same or different.
Compound (1) is a compound (1-A) in which each of R ¹ and R ² is a fluorinated alkyl group having 1 to 10 carbon atoms, or R ¹ is one or more carbon atoms between carbon atoms A compound (1-B) which is a fluorinated alkyl group having 1 to 10 carbon atoms having an etheric oxygen atom and R ² is a fluorinated alkyl group having 1 to 10 carbon atoms is preferred.

The compound (1) is preferably a compound having a total carbon number of 4 to 10 and more preferably a compound of 4 to 8 because the boiling point is too low when the carbon number is too small and the viscosity increases when the carbon number is too large. The molecular weight of the compound (1) is preferably 150 to 800, more preferably 150 to 500, and particularly preferably 200 to 500. Since the number of etheric oxygen atoms in the compound (1) affects flammability, the number of etheric oxygen atoms in the case of the compound (1) having an etheric oxygen atom is preferably 1 to 4, and 1 or 2 Is more preferable. Further, since the nonflammability is improved when the fluorine content in the compound (1) is increased, the ratio of the mass of fluorine atoms to the molecular weight of the compound (1) is preferably 50% or more, and more preferably 60% or more.
Specific examples of the compound other than the compound (1-A), the compound (1-B), the compound (1-A) and the compound (1-B) include, for example, the compounds described in International Publication No. 2009/133899, etc. Is mentioned.

The nonaqueous electrolytic solution of the present invention can easily dissolve a lithium salt and easily obtain a nonaqueous electrolytic solution having excellent nonflammability and high conductivity. Preferably, the compound (1-A) when ¹ and R ² is a fluorinated alkyl group having 1 to 10 carbon atoms is essential, and CF ₃ CH ₂ OCF ₂ CF ₂ H (trade name: AE-3000) , manufactured by Asahi Glass _{Co.), CHF 2 CF 2 CH 2} OCF 2 CF 2 H, CF 3 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CH 2 OCF 2 CHFCF 3, and _{CHF 2 CF 2 CH 2 OCF 2} CFHCF 3 More preferably, at least one selected from the group consisting of: CF ₃ CH ₂ OCF ₂ CF ₂ H and CHF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ is used. It is particularly preferable to make one essential.

In the compound (2), X may have a linear structure or a branched structure. X is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 2 to 4 carbon atoms. The alkylene group preferably has a linear structure or a branched structure. When the alkylene group in X has a branched structure, the side chain is preferably an alkyl group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms having an etheric oxygen atom.

Furthermore, as the compound (2), X is CH ₂ , CH ₂ CH ₂ , CH (CH from the point that a lithium salt is uniformly dissolved and a non-aqueous electrolyte with excellent nonflammability and high conductivity is easily obtained. ₃₎ CH _2, and _CH 2 _CH 2 1 or a is compound selected from the group consisting of CH ₂ (2) is preferred.
Specific examples of the compound (2) include a compound represented by the following formula.
The nonaqueous electrolytic solution of the present invention is easily dissolved in a lithium salt, and a nonconductive electrolytic solution having excellent nonflammability and high conductivity is easily obtained. It is preferable that at least one of the compound in which X is CH ₂ CH ₂ and the compound in which X is CH (CH ₃ ) CH ₂ is essential, the compound in which X is CH ₂ CH ₂ and X is CH (CH ₃ It is more preferable that it consists of at least one of the compounds that are CH _{2, and} it is only one of the compound that X is CH ₂ CH ₂ or the compound that X is CH (CH ₃ ) CH ₂ preferable.

The fluorine-containing ether solvent may be any one of the use of only the compound (1), the use of only the compound (2), or the combined use of the compound (1) and the compound (2), and the use of only the compound (1). Or the use of only compound (2).

The content of the fluorinated ether solvent in the non-aqueous electrolyte is preferably 20 to 95% by volume, more preferably 30 to 90% by volume, and particularly preferably 40 to 80% by volume based on the total amount of the solvent.
When the compound (1) and the compound (2) are used in combination as the fluorine-containing ether solvent, the content of the compound (1) with respect to the total amount of the compound (1) and the compound (2) is 1 to 99% by volume. Preferably, it is 10 to 90% by volume.
In the present invention, the use of a fluorine-containing ether solvent in combination with the compounds (3) and (4) described later improves the low-temperature characteristics as an electrolytic solution.

[Compound (3)]
The compound (3) is a solvent that plays a role of uniformly dissolving the lithium salt in the fluorinated ether solvent by efficiently solvating with the lithium salt. Part or all of the compound (3) is considered to form a complex with the lithium salt in the electrolytic solution.

In the formula (3), Q ¹ is a linear alkylene group having 1 to 4 carbon atoms, or one or more hydrogen atoms of the linear alkylene group is an alkyl group having 1 to 5 carbon atoms, or a carbon atom. A group substituted with an alkyl group having 1 to 5 carbon atoms and containing one or more etheric oxygen atoms between carbon atoms. R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms, or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ⁴ .

Q ¹ is preferably a linear alkylene group having 1 to 4 carbon atoms, particularly preferably —CH ₂ CH ₂ —.
R ³ and R ⁴ are each preferably a methyl group or an ethyl group, particularly preferably a methyl group.
In the nonaqueous electrolytic solution of the present invention, the compound (3) preferably comprises the following compound (3A), and more preferably comprises only the compound (3A).

However, in the formula (3A), R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ⁴ .
As the compound (3A), monoglyme (1,2-dimethoxyethane) or 1,2-diethoxyethane is preferable, and monoglyme is particularly preferable.
A compound (3) may be used individually by 1 type, and may use 2 or more types together.

[Compound (4)]
Similar to the compound (3), the compound (4) is a solvent that plays a role in uniformly dissolving the lithium salt in a fluorinated ether solvent by efficiently solvating with the lithium salt. It is thought that a part or all of the compound (4) forms a complex with a lithium salt in the electrolytic solution.

However, in the formula (4), m is an integer of 2 to 4.
Q ² represents a linear alkylene group having 1 to 4 carbon atoms, or one or more of hydrogen atoms of the linear alkylene group is an alkyl group having 1 to 5 carbon atoms, or a carbon atom-carbon atom. A group substituted with an alkyl group having 1 to 5 carbon atoms containing one or more etheric oxygen atoms. Q ² may be the same group or different groups.
R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms, or an alkylene group having 1 to 10 carbon atoms formed by connecting R ⁵ and R ⁶ together.

In the compound (4), m is preferably 2 to 3, and m is particularly preferably 2.
Q ² is preferably a linear alkylene group having 1 to 4 carbon atoms, particularly preferably —CH ₂ CH ₂ —. Further, when Q ² is only one kind, it is preferably composed of only —CH ₂ CH ₂ —. When Q ² is 2 or more, it is preferably composed of a combination of —CH ₂ CH ₂ — and Q ² other than —CH ₂ CH ₂ —.
R ⁵ and R ⁶ are each preferably a methyl group or an ethyl group, and more preferably a methyl group.
In the nonaqueous electrolytic solution of the present invention, the compound (4) preferably comprises the following compound (4A), and more preferably comprises only the compound (4A).

However, in the formula (4A), m is an integer of 2 to 4. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ⁵ and R ⁶ .

In the compound (4A), m is particularly preferably 2.
In the compound (4A), R ⁵ and R ⁶ are each preferably a methyl group or an ethyl group, and more preferably a methyl group.

In the compound (4A), compounds in which R ⁵ and R ⁶ are methyl groups and m is 2 to 4 are diethylene glycol dimethyl ether (diglyme, m = 2), triethylene glycol diethyl ether (triglyme, m = 3), tetra Ethylene glycol diethyl ether (tetraglyme, m = 4).
Examples of other compounds contained in the compound (4A) include diethylene glycol-diethyl ether, diethylene glycol-di-n-propyl ether, diethylene glycol-di-iso-propyl ether, diethylene glycol-di-n-butyl ether, triethylene glycol- Diethyl ether, triethylene glycol-di-n-propyl ether, triethylene glycol di-iso-propyl ether, triethylene glycol-di-n-butyl ether, tetraethylene glycol-diethyl ether, tetraethylene glycol di-n-propyl ether , Tetraethylene glycol di-iso-propyl ether, and tetraethylene glycol di-n-butyl ether.

In the compound (4), R ⁵ and R ⁶ are a methyl group or an ethyl group, and examples of the compound other than the compound (4A) include compounds described in International Publication No. 2009/133899.
In the compound (4), examples of the compound in which R ⁵ and R ⁶ are linked to form an alkylene group having 1 to 10 carbon atoms include 12-crown-4, 14-crown-4, 15- Crown-5, 18-crown-6 and the like.
A compound (4) may be used individually by 1 type, and may use 2 or more types together.

As the compound (4), diglyme, triglyme, tetraglyme, diethylene glycol diethyl ether, triethylene glycol diethyl ether, or tetra is preferable because it is easy to improve low temperature characteristics while maintaining other performances such as conductivity and high rate characteristics. Ethylene glycol diethyl ether is preferred, diglyme or diethylene glycol diethyl ether is more preferred, and diglyme is particularly preferred.
In addition, diglyme, triglyme, tetraglyme, and diethylene glycol diethyl are preferable in that the viscosity (20 ° C.) is 5 cP or less and the practical solvent viscosity of the non-aqueous electrolyte is excellent, and the obtained non-aqueous electrolyte exhibits good conductivity. Ether, triethylene glycol diethyl ether, or tetraethylene glycol diethyl ether is preferable, and diglyme, triglyme, or tetraglyme is more preferable in terms of excellent balance between viscosity and flash point characteristics.

The total content of the compound (3) and the compound (4) in the non-aqueous electrolyte is preferably 0.2 to 4.0 times mol with respect to the total amount of the lithium salt in the non-aqueous electrolyte. It is more preferably 0.5 to 3.0 times, and particularly preferably 0.5 to 2.0 times mole. If the molar ratio of the total amount of the compound (3) and the compound (4) with respect to the lithium salt is not less than the lower limit of the above range, the lithium salt can be easily dissolved uniformly in the fluorinated ether solvent. Moreover, if the molar ratio of the total amount of the compound (3) and the compound (4) with respect to the lithium salt is less than or equal to the upper limit of the above range, a nonaqueous electrolytic solution excellent in oxidation resistance and nonflammability can be easily obtained.

The total content of the compound (3) and the compound (4) in the nonaqueous electrolytic solution is preferably 5 to 30% by volume, more preferably 10 to 30% by volume, with respect to the total amount of the solvent. % Is more preferable, and 10 to 22% by volume is particularly preferable.

The present invention is characterized in that the compound (3) and the compound (4) coexist in the nonaqueous electrolytic solution. By allowing two ether compounds to coexist, crystal precipitation from the electrolytic solution at a low temperature can be suppressed. The molar ratio (M _III / M _IV ) of the compound (3) (molar amount: M _III ) to the compound (4) (molar amount: M _IV ) in the non-aqueous electrolyte is preferably 10/90 to 90/10. 15/85 to 85/15 are more preferable. By setting the molar ratio (M _III / M _IV ), there is an advantage that the crystal precipitation from the electrolytic solution at a low temperature can be suppressed and the electrolytic solution can have high conductivity. When the nonaqueous electrolytic solution of the present invention does not contain the compound (8) described later, the molar ratio (M _III / M _IV ) is particularly preferably 40/60 to 80/20 from the viewpoint of conductivity. When the nonaqueous electrolytic solution of the present invention contains the compound (8) described later, the molar ratio (M _III / M _IV ) is particularly preferably 20/80 to 40/60 from the viewpoint of conductivity.

Total number of etheric oxygen atoms derived from compound (3) and compound (4) (N _Li ) relative to the total number of lithium atoms derived from lithium salt (N _Li ) contained in the non-aqueous electrolyte of the present invention (N The ratio ( _{O 2} ) (N 2 _{O 3} / N _Li ) is preferably 1 or more, more preferably 2 or more, from the viewpoint that the lithium salt can be easily dissolved in the fluorine-containing ether solvent. Further, the ratio (N 2 _{O 3} / N _Li ) is preferably 6 or less, more preferably 5 or less from the viewpoint of suppressing the battery capacity in charge / discharge under high rate conditions and further improving the cycle characteristics at high voltage. 4 or less is particularly preferable.

[Compound (8)]
The nonaqueous electrolytic solution of the present invention is a compound having a ring structure composed of carbon atoms and oxygen atoms, the ring structure having a bond represented by —O—C (═O) —O—, and a molecule. It is preferable to contain the compound (8) which does not contain a carbon-carbon unsaturated bond. The compound (8) has a high polarity and plays a role of suppressing a decrease in battery capacity during charge / discharge at a high rate. Moreover, the electrical conductivity of this non-aqueous electrolyte is improved by improving the dissociation degree of lithium salt. In addition, by efficiently solvating with a lithium salt, it helps to dissolve the lithium salt uniformly in a fluorinated ether solvent.
Note that in this specification, a carbonate compound refers to a compound including a bond represented by —O—C (═O) —O— (hereinafter also referred to as “carbonate bond”). A cyclic carbonate compound is a compound having a ring structure containing a carbonate bond. The carbon-carbon unsaturated bond is a carbon-carbon double bond or a carbon-carbon triple bond.

The ring structure in compound (8) is preferably a 4- to 10-membered ring, more preferably a 4- to 7-membered ring, more preferably a 5- to 6-membered ring, and particularly preferably a 5-membered ring from the viewpoint of availability.
The ring structure of compound (8) is preferably a ring structure having one carbonate bond, and more preferably a ring structure formed by linking a carbonate bond to a linear alkylene group. The linear alkylene group preferably has 1 to 7 carbon atoms, more preferably 1 to 4, more preferably 2 or 3, and particularly preferably 2. Moreover, the said linear alkylene group may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, and a halogenated alkyl group. As a halogen in a halogen atom or a halogenated alkyl group, a chlorine atom or a fluorine atom is preferable.
As the compound (8), the following compound (8-1) is preferred.

However, in the formula (8-1), R ⁷ to R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group, or a halogenated alkyl group. In addition, since compound (8-1) is less likely to be oxidized and is more suitable for use under high voltage conditions, at least one of R ⁷ to R ¹⁰ is preferably a halogen atom.
Specific examples of the compound (8-1) include, for example, propylene carbonate, ethylene carbonate, butylene carbonate, 4-chloro-1,3-dioxolan-2-one, 4-fluoro-1,3-dioxolan-2-one 4-trifluoromethyl-1,3-dioxolan-2-one.

As the compound (8), one or more hydrogen atoms bonded to a carbon atom forming a cyclic carbonate compound selected from the group consisting of propylene carbonate, ethylene carbonate, and butylene carbonate, or a ring structure of the cyclic carbonate compound are included. , A halogen atom, an alkyl group, or a compound substituted with a halogenated alkyl group is preferable. From the viewpoint of easy availability and properties of the electrolytic solution, ethylene carbonate, propylene carbonate or 4-fluoro-1,3-dioxolane-2 -ON is preferred.
As the compound (8), one type of compound may be used alone, or two or more types of compounds may be used in combination.

The content of the compound (8) in the nonaqueous electrolytic solution is preferably 5 to 60% by volume, more preferably 5 to 50% by volume, and still more preferably 10 to 40% by volume with respect to the total amount of the solvent. If content of a compound (8) is more than the lower limit of the said range, it will be easy to suppress the fall of the battery capacity in charging / discharging at a high rate. In addition, the dissociation degree of the lithium salt is improved, and the electrical conductivity becomes better. If content of the compound (8) in a non-aqueous electrolyte is below the upper limit of the said range, it will be easy to obtain the non-aqueous electrolyte excellent in flame retardance.

The ratio (N _VIII / N _Li ) of the total number of moles (N _VIII ) of compound (8) to the total number of moles (N _Li ) of lithium atoms derived from the lithium salt contained in the non-aqueous electrolyte of the present invention is 0.01 to 6 is preferable, 0.1 to 5 is more preferable, and 1 to 4 is particularly preferable. When the ratio (N _VIII / N _Li ) is equal to or greater than the lower limit of the above range, it is easy to suppress a decrease in battery capacity during charge / discharge at a high rate. If the ratio (N _VIII / N _Li ) is less than or equal to the upper limit of the above range, the flame retardancy of the electrolyte solution can be easily maintained.

The factor that suppresses the decrease in battery capacity during charging and discharging at a high rate by the compound (8) is not necessarily clear, but is considered as follows.
In the charge / discharge of the secondary battery, lithium ions need to decoordinate and react with the electrode active material of the electrode. When the highly polar compound (8) is used as an auxiliary solvent in the electrolyte, the depolarization energy is lowered by improving the polarity of the whole solvent, and the compounds (3) and (4) are easily decoordinated. Since lithium ions can react efficiently with the electrode active material, it is considered that a decrease in battery capacity during charge / discharge at a high rate is suppressed.

[Compound (9)]
The non-aqueous electrolyte of the present invention may contain a non-fluorinated cyclic carbonate compound. The carbonate compound is preferably included from the viewpoint of charge / discharge characteristics at a high rate, and is preferably not included from the viewpoint of flame retardancy. The carbonate compound is preferably a compound having a ring structure composed of a carbon atom and an oxygen atom, the ring structure having a carbonate bond and a carbon-carbon unsaturated bond in the molecule (9).
The ring structure in the compound (9) is preferably a 4- to 10-membered ring, more preferably a 4- to 7-membered ring, more preferably a 5- to 6-membered ring, and particularly preferably a 5-membered ring from the viewpoint of availability.
The ring structure of compound (9) is preferably a ring structure having one carbonate bond.
The carbon-carbon unsaturated bond of compound (9) may be inside the ring structure or outside the ring structure. The carbon-carbon unsaturated bond is preferably 1 to 5 in the molecule, more preferably 1 to 3, and more preferably 1 to 2 from the viewpoint of availability and durability of the nonaqueous electrolyte. One is particularly preferred.
As the compound (9), the following compound (9-1) or compound (9-2) is preferred.

In the formula, R ¹¹ and R ¹² are each independently a hydrogen atom, a halogen atom, an alkyl group, or a halogenated alkyl group.
R ¹³ to R ¹⁶ are each independently a hydrogen atom, an alkyl group, a vinyl group or an allyl group, and at least one of R ¹³ to R ¹⁶ is a vinyl group or an allyl group.

As the compound (9), only the compound (9-1) may be used, or only the compound (9-2) may be used, and the compound (9-1) and the compound (9-2) are used in combination. May be.
As the compound (9), 4-vinyl-1,3-dioxolan-2-one, dimethyl vinylene carbonate or vinylene carbonate is preferable, and vinylene carbonate is particularly preferable.

When charging with a secondary battery using a non-aqueous electrolyte containing compound (9), compound (9) decomposes on the surface of the negative electrode (for example, carbon electrode) to form a stable coating. Since the film formed of the compound (9) can reduce the resistance at the electrode interface, the effect of promoting the intercalation of lithium ions into the negative electrode can be obtained. That is, the impedance formed at the negative electrode interface is reduced by the coating formed of the compound (9) in the nonaqueous electrolytic solution, thereby promoting the intercalation of lithium ions into the negative electrode. Further, since the compound (9) has a high polarity like the compound (8), the intercalation of lithium ions into the negative electrode is promoted and the cycle characteristics are improved without impeding the effect of the compound (8).

The content of the compound (9) in the non-aqueous electrolyte is long-term flame retardancy, suppression of phase separation and generation of carbon dioxide in the non-aqueous electrolyte, suppression of deterioration of low temperature characteristics, and lithium salt From the viewpoint of easily having the effect of improving solubility, it is preferably 0.01 to 10.0% by volume, more preferably 0.05 to 5.0% by volume, and more preferably 0.1 to 3. 0% by volume is particularly preferred.

[Preferred composition of non-aqueous electrolyte]
As the nonaqueous electrolytic solution of the present invention, the following composition 1 or composition 2 is preferable because the intended effect of the present invention is large.
(Composition 1)
LiPF ₆ ; Compound (5), FSO ₂ N (Li) SO ₂ F, CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N (Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ One or more lithium salts selected from the group consisting of Compound (6), Compound (7), and LiBF ₄ ; one or more fluorine-containing ether solvents selected from the group consisting of Compound (1) and Compound (2) Compound (3A); Compound (4A); A non-aqueous electrolyte for a secondary battery.
(Composition 2)
LiPF ₆ ; Compound (5), FSO ₂ N (Li) SO ₂ F, CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N (Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ One or more lithium salts selected from the group consisting of Compound (6), Compound (7), and LiBF ₄ ; one or more fluorine-containing ether solvents selected from the group consisting of Compound (1) and Compound (2) Compound (3A); Compound (4A); and Compound (8-1); Non-aqueous electrolyte for secondary battery.

As the nonaqueous electrolytic solution of the present invention, composition 3 or 4 is more preferable.
(Composition 3)
One or more lithium selected from the group consisting of LiPF ₆ ; CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N (Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ , and LiBF _{4 salt; CF 3 CH 2 OCF 2 CF} 2 H, CHF 2 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CH 2 OCF 2 CHFCF 3, CHF 2 CF 2 CH ₂ OCF ₂ CFHCF ₃ , a compound represented by the formula (2) and X is CH ₂ CH ₂ , and a group represented by the formula (2) and X is CH (CH ₃ ) CH ₂ Non-aqueous secondary battery containing one or more fluorine-containing ether solvents selected from: monoglyme; and diglyme, triglyme or tetraglyme Solution solution.
(Composition 4)
LiPF ₆ ; one or more lithium salts selected from the group consisting of CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N (Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ , LiBF _{4 ; CF 3 CH 2 OCF 2 CF} 2 H, CHF 2 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CF 2 CH 2 OCF 2 CF 2 H, CF 3 CH 2 OCF 2 CHFCF 3, CHF 2 CF 2 CH 2 OCF ₂ CFHCF ₃ , a compound represented by the formula (2) and X is CH ₂ CH ₂ and a group represented by the formula (2) and X is CH (CH ₃ ) CH ₂ At least one fluorine-containing ether solvent selected; monoglyme; diglyme, triglyme or tetraglyme; and ethylene carbonate or The non-aqueous electrolyte secondary battery containing, pyrene carbonate.

As the nonaqueous electrolytic solution of the present invention, composition 5 or 6 is more preferable.
(Composition 5)
A non-aqueous electrolyte for a secondary battery containing a lithium salt essentially comprising LiPF ₆ , CHF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ , monoglyme, and diglyme.
(Composition 6)
A secondary battery non-aqueous electrolyte containing a lithium salt essentially comprising LiPF ₆ , CHF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ , monoglyme, diglyme, and ethylene carbonate or propylene carbonate.
The compositions 1 to 6 may contain the compound (9). As the compound (9), vinylene carbonate is preferable.

[Other compounds]
The non-aqueous electrolyte in the present invention does not undergo phase separation and does not interfere with the effects of the present invention, and the lithium salt, the fluorinated ether solvent, the compound (3), the compound (4), and the compound (8). And a compound other than the compound (9) (hereinafter referred to as “other compounds”).
Other compounds include fluorine-containing alkanes; carboxylic acid esters such as propionic acid alkyl esters, malonic acid dialkyl esters and acetic acid alkyl esters; cyclic carboxylic acid esters such as γ-butyrolactone; cyclic sulfonic acid esters such as propane sultone; sulfone Examples include acid alkyl esters; phosphoric acid alkyl esters; carbonitriles such as acetonitrile, isobutyronitrile, and pivalonitrile.
The content in the case of using other compounds other than the fluorinated alkane in the non-aqueous electrolyte is preferably more than 0 to 20% by volume and more than 0 to 15% by volume with respect to the total volume of the non-aqueous electrolyte. More preferably, more than 0.01 to 10% by volume is particularly preferable.

When the non-aqueous electrolyte of the present invention contains a fluorinated alkane as another compound, the vapor pressure of the non-aqueous electrolyte can be suppressed and the non-flammability of the non-aqueous electrolyte can be further improved. The fluorine-containing alkane refers to a compound in which one or more hydrogen atoms in the alkane are substituted with fluorine atoms and hydrogen atoms remain. In the present invention, a fluorine-containing alkane having 4 to 12 carbon atoms is preferred. Among these, when a fluorine-containing alkane having 6 or more carbon atoms is used, an effect of reducing the vapor pressure of the non-aqueous electrolyte can be expected, and when the carbon number is 12 or less, the solubility of the lithium salt is easily maintained. Further, the fluorine content in the fluorinated alkane (the fluorine content means the proportion of the mass of fluorine atoms in the molecular weight) is preferably 50 to 80%. If the fluorine content in the fluorine-containing alkane is 50% or more, the nonflammability is further increased. When the fluorine content in the fluorine-containing alkane is 80% or less, the solubility of the lithium salt is easily maintained.

As the fluorine-containing alkane, a compound having a linear structure is preferable. For example, n-C ₄ F ₉ CH ₂ CH ₃ , n-C ₆ F ₁₃ CH ₂ CH ₃ , n-C ₆ F ₁₃ H, n-C ₈ F ₁₇ H, and the like. These fluorine-containing alkanes may be used alone or in combination of two or more.
The content when the fluorine-containing alkane is contained in the non-aqueous electrolyte is preferably 5 to 60% by volume with respect to the total volume of the non-aqueous electrolyte. If content of the said fluorine-containing alkane is 5 volume% or more, it will be easy to reduce a vapor pressure and it will be easy to express nonflammability. If content of the said fluorine-containing alkane is 60 volume% or less, it will be easy to maintain the solubility of lithium salt.

Moreover, it is particularly preferable that the nonaqueous electrolytic solution of the present invention does not contain the following compound (10). The compound (10) is a chain carbonate compound and has a low polarity unlike the cyclic carbonate compound such as the compound (9). Therefore, when compound (10) is contained in the nonaqueous electrolytic solution of the present invention, flame retardancy is reduced without improving the charge / discharge characteristics under high rate conditions.

However, in the formula (10), R ¹⁷ to R ²² are each independently a hydrogen atom, a halogen atom, an alkyl group, or a halogenated alkyl group.

The non-aqueous electrolyte of the present invention may contain other components as required in order to improve the function of the non-aqueous electrolyte. Other components include, for example, conventionally known overcharge inhibitors, dehydrating agents, deoxidizing agents, capacity maintenance characteristics after high-temperature storage and characteristics improvement aids for improving cycle characteristics, electrolyte solutions and electrode active materials. Surfactant for improving wettability is mentioned.

Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorinated anisole such as 2,4-difluoroanisole, 2,5-difluoroanisole and 2,6-difluoroaniol Compounds. An overcharge inhibitor may be used individually by 1 type, and may use 2 or more types together.
When the non-aqueous electrolyte contains an overcharge inhibitor, the content of the overcharge inhibitor in the non-aqueous electrolyte is preferably 0.01 to 5% by mass. By containing an overcharge inhibitor in an amount of 0.01% by mass or more in the non-aqueous electrolyte, it becomes easier to suppress the secondary battery from bursting or igniting due to overcharge, and the secondary battery can be used more stably. .

Examples of the dehydrating agent include molecular sieves, sodium sulfate, magnesium sulfate, calcium hydride, sodium hydride, potassium hydride, lithium aluminum hydride and the like. As the solvent used in the nonaqueous electrolytic solution of the present invention, it is preferable to use a solvent obtained by performing rectification after dehydrating with the dehydrating agent. Moreover, you may use the solvent which performed only the dehydration by the said dehydrating agent, without performing rectification.

Examples of characteristic improvement aids for improving capacity retention characteristics and cycle characteristics after high-temperature storage include carbonate compounds such as phenylethylene carbonate, erythritan carbonate, spiro-bis-dimethylene carbonate; succinic anhydride, anhydrous glutar Carboxylic acid anhydrides such as acid, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, phenylsuccinic anhydride; Ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, diphenyl sulfone, methyl phenyl sulfone, dibutyl disulfide, dicyclohex Sulfur-containing compounds such as rudisulfide, tetramethylthiuram monosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3- Nitrogen-containing compounds such as methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane and cycloheptane; fluorobenzene, difluorobenzene and hexafluoro Examples thereof include fluorine-containing aromatic compounds such as benzene and benzotrifluoride. These characteristic improvement aids may be used alone or in combination of two or more.
When the non-aqueous electrolyte contains a property improving aid, the content of the property improving aid in the non-aqueous electrolyte is preferably 0.01 to 5% by mass.

As a surfactant for improving the wettability between the electrolyte and the electrode active material, any of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant may be obtained. An anionic surfactant is preferred because it is easy and has a high surfactant effect. As the surfactant, a fluorine-containing surfactant is preferable from the viewpoint of high oxidation resistance and good cycle characteristics and rate characteristics.
As the fluorine-containing surfactant, the following compound (11-1) or compound (11-2) is preferable.

In the formula, R ²³ and R ²⁴ are each independently a perfluoroalkyl group having 4 to 20 carbon atoms, or a perfluoroalkyl group having 1 or more etheric oxygen atoms between carbon atoms and carbon atoms. A fluoroalkyl group;
M ¹ and M ² are each independently an alkali metal or NH (R ²⁵ ) ₃ (R ²⁵ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and may be the same group or different groups. Good.)

R ²³ and R ²⁴ are each a perfluoroalkyl group having 4 to 20 carbon atoms, or one or more etheric groups between carbon atoms and carbon atoms from the viewpoint that the degree of reducing the surface tension of the nonaqueous electrolytic solution is good. A perfluoroalkyl group having 4 to 20 carbon atoms having an oxygen atom is preferable. From the viewpoint of excellent solubility and environmental accumulation, a perfluoroalkyl group having 4 to 8 carbon atoms, or one per carbon atom to carbon atom A perfluoroalkyl group having 4 to 8 carbon atoms having the above etheric oxygen atom is more preferred.
As the alkali metal of M ¹ and M ² , Li, Na, or K is preferable. As M ¹ and M ² , NH ⁴⁺ is particularly preferable.

Specific examples of the compound (11-1) include, for example, C ₄ F ₉ COO ^— NH ₄ ⁺ , C ₅ F ₁₁ COO ^— NH ₄ ⁺ , C ₆ F ₁₃ COO ^— NH ₄ ⁺ , C ₅ F ₁₁ COO ^−. NH (CH ₃ ) ₃ ⁺ , C ₆ F ₁₃ COO ⁻ NH (CH ₃ ) ₃ ⁺ , C ₄ F ₉ COO ⁻ Li ⁺ , C ₅ F ₁₁ COO ⁻ Li ⁺ , C ₆ F ₁₃ COO ⁻ Li ⁺ , C ^{_{3 F 7 OCF (CF 3)}} COO - NH 4 +, C 3 F 7 OCF (CF 3) CF 2 OCF (CF 3) COO - NH 4 +, C 3 F 7 OCF (CF 3) COO - NH (CH ^{_{3) 3 +, C 3 F}} 7 OCF (CF 3) CF 2 OCF (CF 3) COO - NH (CH 3) 3 +, C 3 F 7 OCF (CF 3) COO - Li +, C 2 F 5 OC ₂ F _{4 ^{CF 2 COO - Li +, C}} 2 F 5 OC 2 F 4 OCF 2 COO - NH 4 +, C 3 F 7 OCF (CF 3) CF 2 OCF (CF 3) COO - Li + fluorinated carboxylates such as Is mentioned.
Among these, C ₅ F ₁₁ COO ⁻ NH ₄ ⁺ , C ₅ F ₁₁ COO ⁻ Li ⁺ , and C ₆ F ₁₃ COO ⁻ Li are preferred because of their good solubility in non-aqueous electrolytes and the effect of reducing surface tension. ^{_{+, C 3 F 7 OC (}} CF 3) FCOO - NH 4 +, C 3 F 7 OCF (CF 3) CF 2 OCF (CF 3) COO - NH 4 +, C 3 F 7 OCF (CF 3) COO - ^{_{Li +, C 3 F 7 OCF}} (CF 3) CF 2 OCF (CF 3) COO - Li +, C 2 F 5 OC 2 F 4 OCF 2 COO - Li +, or _{C 2 F 5 OC 2 F 4} OCF 2 COO ⁻ NH ₄ ⁺ is preferred.

Specific examples of the compound (11-2) is, for ^{_{example, C 4 F 9 SO 3 -}} NH 4 +, C 5 F 11 SO 3 - NH 4 +, C 6 F 13 SO 3 - NH 4 +, C 4 F ^{_{9 SO 3 - NH (CH 3}} ) 3 +, C 5 F 11 SO 3 - NH (CH 3) 3 +, C 6 F 13 SO 3 - NH (CH 3) 3 +, C 4 F 9 SO 3 - Li ^{_{+, C 5 F 11 SO 3}} - Li +, C 6 F 13 SO 3 - Li +, C 3 F 7 OC (CF 3) FCF 2 OC (CF 3) FSO 3 - NH 4 +, C 3 F 7 OC _{(CF 3) FCF 2 OC (} CF 3) FCF 2 OC (CF 3) FSO 3 - NH 4 +, HCF 2 CF 2 OCF 2 CF 2 SO 3 - NH 4 +, CF 3 CFHCF 2 OCF 2 CF 2 SO 3 ^- NH ₄ ^+, C ^{_{3 F 7 OC (CF 3)}} FSO 3 - NH 4 +, C 3 F 7 OC (CF 3) FCF 2 OC (CF 3) FSO 3 - NH (CH 3) 3 +, C 3 F 7 OC (CF 3 _{) FCF 2 OC (CF 3)} FCF 2 OC (CF 3) FSO 3 - NH (CH 3) 3 +, HCF 2 CF 2 OCF 2 CF 2 SO - NH (CH 3) 3 +, CF 3 CFHCF 2 OCF 2 ^{_{CF 2 SO 3 - NH (CH}} 3) 3 +, C 3 F 7 OC (CF 3) FSO 3 - NH (CH 3) 3 +, C 3 F 7 OC (CF 3) FCF 2 OC (CF 3) FSO ^{_{3 - Li +, C 3 F}} 7 OC (CF 3) FCF 2 OC (CF 3) FCF 2 OC (CF 3) FSO 3 - Li +, HCF 2 CF 2 OCF 2 CF 2 SO 3 - Li +, CF _{3 CFHCF 2 OCF 2 CF 2 SO} 3 - Li +, C 3 F 7 OC (CF 3) FSO 3 - fluorinated sulfonic acid salts of Li ⁺ and the like.
Among them, solubility in the nonaqueous electrolytic solution, from the viewpoint of satisfactory effect of reducing the surface ^{_{tension, C 4 F 9 SO 3 -}} NH 4 +, C 6 F 13 SO 3 - NH 4 +, C 4 F 9 ^{_{SO 3 - Li +, C 6}} F 13 SO 3 - Li +, C 8 F 17 SO 3 - Li +, C 3 F 7 OC (CF 3) FCF 2 OC (CF 3) FSO 3 - NH 4 +, C _{3 F 7 OC (CF 3)} FCF 2 OC (CF 3) FSO 3 - Li +, C 3 F 7 OC (CF 3) FSO 3 - NH 4 +, or _{C 3 F 7 OC (CF 3} ) FSO 3 - Li ⁺ is preferred.
Surfactant may be used individually by 1 type and may use 2 or more types together.

When the non-aqueous electrolyte contains a surfactant, the content of the surfactant in the non-aqueous electrolyte is preferably 5% by mass or less, more preferably 3% by mass or less, and 0.05 to 2% by mass. Further preferred.

The non-aqueous electrolyte of the present invention is used for a secondary battery. In particular, when used as an electrolyte solution for a lithium ion secondary battery, lithium salts can be dissolved well, performances such as conductivity and nonflammability are practically sufficient, and particularly low temperature characteristics are excellent. Moreover, you may use for secondary batteries other than a lithium ion secondary battery. Other secondary batteries include electric double layer capacitors, lithium ion capacitors, and the like.

The non-aqueous electrolyte of the present invention described above has excellent low-temperature characteristics because precipitation of crystals at low temperatures is suppressed while securing other characteristics such as conductivity. This effect is due to the combined use of compound (3) and compound (4), which breaks the symmetry of the glyme complex that is complexed with the lithium salt, changes the association state of the glyme complex in the solution, and dissociates. This is thought to be due to the change in degree and viscosity. Moreover, if the non-aqueous electrolyte of this invention uses a compound (8), the effect which suppresses the fall of the battery capacity in charging / discharging on high-rate conditions will increase.

<Secondary battery>
The nonaqueous electrolytic solution of the present invention is an electrolytic solution for a secondary battery, and is preferably used as an electrolytic solution for a lithium ion secondary battery. The secondary battery is a secondary battery having a negative electrode and a positive electrode and the non-aqueous electrolyte of the present invention.
Examples of the negative electrode include a negative electrode active material capable of inserting and extracting lithium ions, a metal such as lithium metal and lithium alloy, or an electrode containing a metal compound as a negative electrode active material. As the negative electrode active material, known negative electrode active materials for lithium ion secondary batteries can be used, and artificial or natural graphite (graphite) capable of occluding and releasing lithium ions, carbonaceous materials such as amorphous carbon, or metal Examples thereof include metals such as lithium and lithium alloys, and metal compounds. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.

Especially, as a negative electrode active material, a carbonaceous material is preferable. As the carbonaceous material, graphite or a carbonaceous material in which the surface of graphite is coated with amorphous carbon as compared with the graphite is particularly preferable.
Graphite is the d-value (interlayer distance, hereinafter referred to as the lattice plane (002 plane)) determined by X-ray diffraction by the method established by the Japan Society for the Promotion of Science Carbon Material 117th Committee (hereinafter referred to as “Gakushin Law”). The “d value” is simply 0.335 to 0.338 nm, more preferably 0.335 to 0.337 nm. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is preferably 30 nm or more, more preferably 50 nm or more, and particularly preferably 100 nm or more. The graphite ash content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

Further, as a carbonaceous material in which the surface of graphite is coated with amorphous carbon, graphite having a d value of 0.335 to 0.338 nm is used as a core material, and the d value is larger on the surface of the graphite than the graphite. The ratio of graphite (mass W _A ), which is coated with amorphous carbon, and amorphous carbon (mass W _B ) covering the graphite is 80 / weight ratio (W _A / W _B ). It is preferably 20 to 99/1. By using this carbonaceous material, it becomes easy to produce a negative electrode having a high capacity and hardly reacting with the non-aqueous electrolyte.

The particle size of the carbonaceous material is 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 7 μm or more, as a median diameter by a laser diffraction / scattering method. The upper limit of the particle size of the carbonaceous material is preferably 100 μm, more preferably 50 μm, further preferably 40 μm, and particularly preferably 30 μm.

BET specific surface area of the carbonaceous material is preferably at least 0.3 m ² / g, more preferably at least 0.5 m ² / g, more preferably not less than ^{0.7m 2 / g, 0.8m 2 /} g or more Is particularly preferred. The upper limit of the specific surface area of the carbonaceous material is preferably 25.0 m ² / g, more preferably 20.0 m ² / g, more preferably 15.0 m ² / g, particularly preferably 10.0 m ² / g.

The carbonaceous material has a peak intensity I _A of peak P _{A in} the range of 1,570 to 1,620 cm ⁻¹ and 1,300 to 1,400 cm when analyzed by a Raman spectrum using an argon ion laser beam. ^The R value (= I _B / I _A ) represented by the ratio of the peak P _{B in} the range of ⁻¹ to the peak intensity I _B is preferably 0.01 to 0.7. Further, the half width of the peak _{P A} is, it is particularly preferable is preferably 26cm ^-1 or less, and 25 cm ^-1 or less.

Examples of metals that can be used as the negative electrode active material other than metallic lithium include Ag, Zn, Al, Ga, In, Si, Ti, Ge, Sn, Pb, P, Sb, Bi, Cu, Ni, Sr, and Ba. It is done. Moreover, as a lithium alloy, the alloy of lithium and the said metal is mentioned. Moreover, as a metal compound, the said metal oxide etc. are mentioned.
Among these, at least one metal selected from the group consisting of Si, Sn, Ge, Ti and Al, a metal compound containing the metal, a metal oxide, or a lithium alloy is preferable. From the group consisting of Si, Sn and Al One or more selected metals, a metal compound containing the metal, a lithium alloy, or lithium titanate is more preferable.
A metal capable of inserting and extracting lithium ions, a metal compound containing the metal, and a lithium alloy generally have a larger capacity per unit mass than a carbonaceous material typified by graphite, and therefore a higher energy density is required. It is suitable for a secondary battery.

Examples of the positive electrode include an electrode including a positive electrode active material that can occlude and release lithium ions.
As the positive electrode active material, a known positive electrode active material for a lithium ion secondary battery can be used. For example, a lithium-containing transition metal oxide, a lithium-containing transition metal composite oxide using one or more transition metals, a transition Examples thereof include metal oxides, transition metal sulfides, metal oxides, and olivine type metal lithium salts.

Examples of the lithium-containing transition metal oxide include lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide.
The metal contained in the lithium-containing transition metal composite oxide is preferably Al, V, Ti, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Yb, etc. Lithium cobalt composite oxide such as LiCoO ₂ , lithium nickel composite oxide such as LiNiO ₂ , lithium manganese composite oxide such as LiMnO ₂ , LiMn ₂ O ₄ and Li ₂ MnO ₃ , Li (Ni _a Co _b Mn _c ) O ₂ (where a, b, c> 0, and a + b + c = 1), etc., some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are Al, Examples include those substituted with other metals such as Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, and Yb. For example, specifically, LiMn _0.5 Ni _0.5 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiMn _1.5 Ni _{0. 5} O ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMn _1.8 Al _0.2 O _{4 and the} like.
Examples of transition metal oxides include TiO ₂ , MnO ₂ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ , transition metal sulfides TiS ₂ , FeS, MoS ₂ , metal oxides SnO ₂ , Examples thereof include SiO ₂ .
The olivine-type metallic lithium salt is Li _L X _x Y _y O _z F _g (where X is Fe (II), Co (II), Mn (II), Ni (II), V (II), or Cu ( II), Y represents P or Si, and represents a number satisfying 0 ≦ L ≦ 3, 1 ≦ x ≦ 2, 1 ≦ y ≦ 3, 4 ≦ z ≦ 12, and 0 ≦ g ≦ 1, respectively) The indicated substance or a complex thereof. For example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , LiFeP ₂ O ₇ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₂ FePO ₄ F, Li ₂ MnPO ₄ F, Li ₂ NiPO ₄ F, Li ₂ CoPO Examples thereof include ₄ F, Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , Li ₂ NiSiO ₄ , and Li ₂ CoSiO ₄ .
These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

In addition, a material in which a substance having a composition different from that of the main constituent of the positive electrode active material is attached to the surface of the positive electrode active material can be used. Surface adhesion substances include oxides such as aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide; lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.
As the amount of the surface adhesion substance, the lower limit of the mass with respect to the positive electrode active material is preferably 0.1 ppm, more preferably 1 ppm, and particularly preferably 10 ppm. The upper limit is preferably 20%, more preferably 10%, and particularly preferably 5%. The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte on the surface of the positive electrode active material, and can improve the battery life.

As a positive electrode active material, a lithium-containing composite oxide based on an α-NaCrO ₂ structure such as LiCoO ₂ , LiNiO ₂ , LiMnO _2, or the like, LiMn ₂ O, because of its high discharge voltage and high electrochemical stability A lithium-containing composite oxide based on a spinel structure such as ₄ is preferred.

The secondary battery of the present invention has a negative electrode and a positive electrode, one of which is a non-polarizable electrode and the other is a polarizable electrode, or both are non-polarizable electrodes, and the non-aqueous electrolyte of the present invention. The polarizable electrode is preferably mainly composed of an electrochemically inactive material having a high specific surface area, and particularly preferably composed of activated carbon, carbon black, metal fine particles, and conductive oxide fine particles. In particular, it is preferable that an electrode layer made of a carbon material powder having a high specific surface area such as activated carbon is formed on the surface of the metal current collector.

In the production of the electrode, a binder that binds the negative electrode active material or the positive electrode active material is used.
As the binder for binding the negative electrode active material and the positive electrode active material, any binder can be used as long as it is a material that is stable with respect to the solvent and the electrolytic solution used during electrode production. The binder is, for example, a fluororesin such as polyvinylidene fluoride or polytetrafluoroethylene, a polyolefin such as polyethylene or polypropylene, a polymer having an unsaturated bond such as styrene / butadiene rubber, isoprene rubber or butadiene rubber, and a copolymer thereof. Examples thereof include acrylic polymers such as polymers, acrylic acid copolymers, and methacrylic acid copolymers, and copolymers thereof. These binders may be used individually by 1 type, and may use 2 or more types together.

The electrode may contain a thickener, a conductive material, a filler and the like in order to increase mechanical strength and electrical conductivity.
Examples of the thickener include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and polyvinylpyrrolidone. These thickeners may be used individually by 1 type, and may use 2 or more types together.

Examples of the conductive material include carbonaceous materials such as acetylene black, graphite, and carbon black. These electrically conductive materials may be used individually by 1 type, and may use 2 or more types together.

As an electrode manufacturing method, a binder, a thickener, a conductive material, a solvent, etc. are added to a negative electrode active material or a positive electrode active material to form a slurry, which is then applied to a current collector and dried. it can. In this case, the electrode is preferably consolidated by pressing after drying.
If the density of the positive electrode active material layer is too low, the capacity of the secondary battery may be insufficient.

As the current collector, various current collectors can be used, but usually a metal or an alloy is used. Examples of the negative electrode current collector include copper, nickel, and stainless steel, with copper being preferred. Further, examples of the current collector of the positive electrode include metals such as aluminum, titanium, and tantalum or alloys thereof, and aluminum or alloys thereof are preferable, and aluminum is more preferable.

The shape of the secondary battery may be selected according to the application, and may be a coin type, a cylindrical type, a square type or a laminate type. Further, the shapes of the positive electrode and the negative electrode can be appropriately selected according to the shape of the secondary battery.
The charging voltage of the secondary battery of the present invention is preferably 3.4 V or higher, more preferably 4.0 V or higher, and particularly preferably 4.2 V or higher. When the positive electrode active material of the secondary battery is a lithium-containing transition metal oxide, a lithium-containing transition metal composite oxide, a transition metal oxide, a transition metal sulfide, or a metal oxide, the charging voltage is preferably 4.0 V or more, 4.2V or more is more preferable. In addition, when the positive electrode active material is an olivine type lithium metal salt, the charging voltage is preferably 3.2 V or higher, and more preferably 3.4 V or higher.

In order to prevent a short circuit, a porous film is usually interposed as a separator between the positive electrode and the negative electrode of the secondary battery. In this case, the nonaqueous electrolytic solution is used by impregnating the porous membrane. The material and shape of the porous membrane are not particularly limited as long as it is stable with respect to the non-aqueous electrolyte and has excellent liquid retention properties, such as polyvinylidene fluoride, polytetrafluoroethylene, a copolymer of ethylene and tetrafluoroethylene, etc. A porous sheet or non-woven fabric made of a polyolefin resin such as polyethylene or polypropylene is preferred, and a material such as polyethylene or polypropylene is preferred. Moreover, you may use what made these porous membranes impregnate an electrolyte solution and gelatinize it as a gel electrolyte.
The battery case used in the non-aqueous electrolyte of the present invention may be made of any material that is usually used for secondary batteries. Nickel-plated iron, stainless steel, aluminum or alloys thereof, nickel, titanium, and resin materials And film materials.

Since the secondary battery of the present invention described above uses the non-aqueous electrolyte of the present invention, other characteristics such as conductivity are practically sufficient and have excellent low-temperature characteristics.
Therefore, the secondary battery of the present invention includes a mobile phone, a portable game machine, a digital camera, a digital video camera, an electric tool, a notebook computer, a portable information terminal, a portable music player, an electric vehicle, a hybrid vehicle, a train, an aircraft, an artificial It can be used for various applications such as satellites, submarines, ships, uninterruptible power supplies, robots, and power storage systems. The secondary battery of the present invention has particularly preferable characteristics for large-sized secondary batteries such as electric vehicles, hybrid vehicles, trains, airplanes, artificial satellites, submarines, ships, uninterruptible power supply devices, robots, and power storage systems. .

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description. Examples 1 to 8 are examples, and examples 9 to 12 are comparative examples.
[Example 1]
After 1.52 g of LiPF ₆ which is a lithium salt is dispersed in 8.08 mL of trade name “AE3000” (CF ₃ CH ₂ OCF ₂ CF ₂ H, manufactured by Asahi Glass Co., Ltd.) which is a fluorine-containing ether solvent, a solvent is further added. As a non-aqueous electrolyte, 0.26 g of monoglyme which is compound (3) and 1.53 g of diglyme which is compound (4) were added and mixed.

[Examples 2 to 12]
A nonaqueous electrolytic solution was obtained in the same manner as in Example 1 except that the composition of the lithium salt and the solvent was changed as shown in Table 1.

<Evaluation of low temperature characteristics and conductivity>
[Evaluation methods]
With respect to the non-aqueous electrolytes obtained in Examples 1 to 12, the crystal precipitation temperature and the conductivity were measured. (Crystal precipitation temperature)
In each example, 5 mL of non-aqueous electrolyte was put into a 20 mL capacity glass vial and placed in a thermostatic bath. Thereafter, the temperature of the thermostatic chamber was lowered from 25 ° C. to −35 ° C. by 10 ° C. After the internal temperature of the thermostatic bath reached each set temperature, the temperature was maintained for 1 hour, and then each non-aqueous electrolyte in the bath was observed to confirm the presence or absence of crystal precipitation. When crystals were precipitated, the temperature was taken as the crystal precipitation temperature.

(conductivity)
The conductivity was measured at 25 ° C. using the known method described in “Molten salt and high temperature chemistry, 2002, 45, 43” for the obtained nonaqueous electrolytic solution.

Table 1 shows the measurement results of the crystal precipitation temperature and conductivity.

However, the abbreviations in Table 1 have the following meanings.
AE3000: CF ₃ CH ₂ OCF ₂ CF ₂ H
In the case of the electrolytic solution described with “−” in the column of the crystal precipitation temperature, no crystal precipitation was observed at −35 ° C.

As shown in Table 1, the non-aqueous electrolyte using a combination of monoglyme and diglyme is excellent in low temperature characteristics because of its low crystal precipitation temperature, and has improved conductivity.

The non-aqueous electrolyte for secondary battery and the secondary battery of the present invention achieve excellent low-temperature characteristics while ensuring performance such as conductivity. Therefore, it can be suitably used for a secondary battery for various uses such as a mobile phone, a notebook computer, and an electric vehicle. In addition, the non-aqueous electrolyte for secondary battery of the present invention dissolves lithium salt well and has excellent nonflammability, so it can be used for other electricity storage devices such as electric double layer capacitors and lithium ion capacitors. it can.
The entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2010-283154 filed on December 20, 2010 are incorporated herein as the disclosure of the specification of the present invention. Is.

Claims (12)

1. A lithium salt, a fluorine-containing ether solvent selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), a compound represented by the following formula (3), and the following formula ( 4) A nonaqueous electrolytic solution for a secondary battery, comprising the compound represented by
   

   

   (Wherein R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a fluorinated alkyl group having 1 to 10 carbon atoms, or 3 to 10 carbon atoms) A fluorinated cycloalkyl group, an alkyl group having 1 to 10 carbon atoms having one or more etheric oxygen atoms between carbon atoms and carbon atoms, or one or more etheric oxygen atoms between carbon atoms and carbon atoms And a fluorinated alkyl group having 1 to 10 carbon atoms, wherein one or both of R ¹ and R ² is a fluorinated alkyl group.
   X is an alkylene group having 1 to 5 carbon atoms, a fluorinated alkylene group having 1 to 5 carbon atoms, an alkylene group having 1 to 5 carbon atoms having one or more etheric oxygen atoms between carbon atoms and carbon atoms, or carbon A fluorinated alkylene group having 1 to 5 carbon atoms having one or more etheric oxygen atoms between atoms and carbon atoms.
   Q ¹ represents a linear alkylene group having 1 to 4 carbon atoms, or one or more hydrogen atoms of the linear alkylene group are alkyl groups having 1 to 5 carbon atoms, or one or more carbon atoms between carbon atoms. And an alkyl group having 1 to 5 carbon atoms containing an etheric oxygen atom.
   R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ⁴ .
   m is an integer of 2-4.
   Q ² represents a linear alkylene group having 1 to 4 carbon atoms, or one or more hydrogen atoms of the linear alkylene group are alkyl groups having 1 to 5 carbon atoms, or one or more carbon atoms between carbon atoms. And an alkyl group having 1 to 5 carbon atoms containing an etheric oxygen atom. Q ² may be the same group or different groups.
   R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkylene group having 1 to 10 carbon atoms formed by linking R ⁵ and R ⁶ . )
2. Formula (3) compounds represented by (molar amount: M _III) and the formula (4) compounds represented by (molar amount: M _IV) molar ratio (M _III / M _IV) is 10/90 ~ The nonaqueous electrolytic solution for a secondary battery according to claim 1, which is 90/10.
3. The non-aqueous electrolyte for secondary batteries according to claim 1 or 2, wherein the compound represented by the formula (3) is essentially a compound represented by the following formula (3A).
   

   

   (However, in the formula, R ³ and R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms, or an alkylene group having 1 to 10 carbon atoms formed by linking R ³ and R ^4. )
4. The non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 3, wherein the compound represented by the formula (4) is essentially a compound represented by the following formula (4A).
   

   

   (In the formula, m is an integer of 2 to 4. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms, or R ¹ and C ⁵ formed by linking R ⁵ and R ^6. 10 alkylene groups.)
5. The compound represented by the above formula (3) and the above formula (4) with respect to the total number of moles (N _Li ) of lithium atoms derived from the lithium salt contained in the nonaqueous electrolyte for secondary batteries. The nonaqueous electrolysis for a secondary battery according to any one of claims 1 to 4, wherein the ratio (N 2 _{O 3} / N _Li ) of the total number of moles (N 2 _{O 3} ) of etheric oxygen atoms derived from the compound is 1 to 6. liquid.
6. The lithium salt is LiPF ₆ , a compound represented by the following formula (5), FSO ₂ N (Li) SO ₂ F, CF ₃ SO ₂ N (Li) SO ₂ CF ₃ , CF ₃ CF ₂ SO ₂ N ( Li) SO ₂ CF ₂ CF ₃ , LiClO ₄ , a compound represented by the following formula (6), a compound represented by the following formula (7), and one or more selected from the group consisting of LiBF ₄ Item 6. The nonaqueous electrolytic solution for secondary battery according to any one of Items 1 to 5.
   

   

   (In the formula, k is an integer of 1 to 5.)
7. The non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 6, comprising a surfactant.
8. The compound represented by the formula (1) is CF ₃ CH ₂ OCF ₂ CF ₂ H, CHF ₂ CF ₂ CH ₂ OCF ₂ CF ₂ H, CF ₃ CF ₂ CH ₂ OCF ₂ CHF ₂ , or CF ₃ CH ₂ OCF. _The nonaqueous electrolytic solution for a secondary battery according to any one of claims 1 to 7, wherein one or more selected from the group consisting of ₂ CHFCF ₃ and CHF ₂ CF ₂ CH ₂ OCF ₂ CFHCF ₃ are essential. .
9. And a compound having a ring structure composed of a carbon atom and an oxygen atom, the ring structure having a bond represented by —O—C (═O) —O—, and carbon-carbon unsaturated in the molecule. The nonaqueous electrolytic solution for a secondary battery according to any one of claims 1 to 8, comprising a compound (8) having no bond.
10. A compound having a ring structure composed of a carbon atom and an oxygen atom, the ring structure including a bond represented by —O—C (═O) —O—, and a carbon-carbon unsaturated bond in the molecule The nonaqueous electrolytic solution for a secondary battery according to any one of claims 1 to 9, comprising the compound (9).
11. The non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 10, which is used as an electrolyte for a lithium ion secondary battery.
12. The material for storing and releasing lithium ions, a negative electrode made of metallic lithium or a lithium alloy, a positive electrode made of a material capable of inserting and extracting lithium ions, and a non-secondary battery non-rechargeable battery according to claim 1 A secondary battery comprising a water electrolyte.