JP2003234127A - Nonaqueous electrolytic solution and lithium secondary battery using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution with a flame-resistance (self-extinguishing characteristic) and a high electric conductivity, and provide a lithium secondary battery with a superior charge-discharge characteristic, a high battery safety and reliability by using the same. <P>SOLUTION: This is the nonaqueous electrolytic solution for the lithium secondary battery used in combination with a positive electrode and a negative electrode wherein storage/release of lithium is possible, and the nonaqueous electrolytic solution including (1) nonaqueous solvent containing phosphate ester or phosphate ester and cyclic carboxylic acid ester, (2) lithium salt dissolved in the nonaqueous solvent, (3) vinylene carbonate compound and/or vinyl ethylene carbonate compound, and (4) cyclic amide compound, and/or cyclic carbamate compound(s), and/or cyclic hetero compound. Further, the lithium secondary battery using these nonaqueous solutions is provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte solution for a lithium secondary battery, and a lithium secondary battery using the same. Specifically, a phosphate ester, or a non-aqueous solvent containing a phosphate ester and a cyclic carboxylic acid ester,
The present invention relates to a non-aqueous electrolytic solution containing a lithium salt, a vinylene carbonate compound and / or a vinylethylene carbonate compound dissolved in the non-aqueous solvent, and a nitrogen-containing compound having a specific structure, and a lithium secondary battery using the same.

The non-aqueous electrolytic solution of the present invention has flame retardancy (self-extinguishing property), has a high electrical conductivity and electrochemical stability, and has a secondary property using the non-aqueous electrolytic solution of the present invention. In batteries, excellent battery charge / discharge characteristics and extremely high battery safety can be obtained.

[0003]

2. Description of the Related Art As a negative electrode active material, a carbonaceous material such as graphite,
LiCoO ₂ , LiNiO ₂ , LiMn as the positive electrode active material
A lithium secondary battery using a lithium-transition metal composite oxide such as ₂ O ₄ is rapidly growing as a new small secondary battery having a high voltage of 4 V class and a high energy density.
As an electrolytic solution used for such a lithium secondary battery, generally, a lithium salt is added to an organic solvent obtained by mixing a high-dielectric constant solvent such as ethylene carbonate or propylene carbonate with a low-viscosity solvent such as dimethyl carbonate or diethyl carbonate. What is dissolved is used.

A lithium secondary battery using these organic non-aqueous electrolytes has a risk of flammable combustion when the battery is damaged or the pressure inside the battery rises and the electrolyte leaks due to some reason. There is a nature.

Therefore, researches for adding a flame retardant to an organic non-aqueous electrolyte to impart flame retardancy have been vigorously pursued. It is known to use phosphoric acid ester as a flame-retardant electrolyte for lithium batteries. O-P (OR) ₃ type phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, and tris (2-chloroethyl) phosphate are used in conventional flame retardant electrolytes for lithium batteries. (See, for example, Patent Documents 1 to 5). Further, at least one R above is a halogen-substituted alkyl,
There is also an electrolytic solution having self-extinguishing property (for example, Patent Document 6).
reference).

However, among the phosphoric acid esters used for these, the electrolytic solution containing trimethyl phosphate has excellent flame retardancy, but depending on the material of the negative electrode (for example, natural graphite or artificial graphite), reductive decomposition is performed. There is a drawback that it is easy to be affected. Therefore, when the compounding amount of trimethyl phosphate is increased, the charge / discharge characteristics of the battery, such as charge / discharge efficiency and discharge capacity, do not satisfy the recently required characteristics.

Further, among phosphoric acid esters, an electrolytic solution containing a phosphoric acid ester having a halogen atom such as chlorine or bromine in the molecule thereof is inferior in redox resistance and generates a high voltage. When applied to a battery or the like, a battery having sufficient charge / discharge characteristics cannot be obtained. Furthermore, a small amount of free halogen ions present as impurities in the electrolytic solution corrodes aluminum used as a positive electrode current collector, which causes deterioration of battery characteristics.

Cyclic phosphoric acid esters are also used in the electrolytic solution (for example, refer to the above-mentioned Patent Document 5). Further, there is also an electrolytic solution for a lithium battery in which 20 to 55% by volume of cyclic phosphoric acid ester is used in combination with a cyclic carbonic acid ester (for example, see Patent Document 7). However, in order to make the electrolyte solution of this system flame-retardant, it is necessary to blend 20% by volume or more of cyclic phosphate ester, and the conductivity decreases as the blending amount of cyclic phosphate ester increases. There is.

Further, it has been shown that the use of a phosphoric acid ester in combination with a vinylene carbonate derivative or a specific cyclic carbonic acid ester is flame-retardant and has improved charge / discharge characteristics (for example, Patent Documents 8 to 9). reference).

However, misuse of the lithium secondary battery
During abuse, the battery may be placed in a high temperature atmosphere, or the battery itself may reach a high temperature state due to an internal short circuit or an external short circuit, which suggests that a thermal decomposition reaction of the battery occurs. In the electrolytic solution using ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, etc. as the main solvent as proposed so far, the battery is 100
It has been suggested that extremely high heat generation and decomposition gas may occur when placed in high temperature above ℃,
From the viewpoint of improving the safety of the battery, a flame-retardant electrolytic solution in which the thermal decomposition rate of the battery is suppressed has been earnestly desired.

[0011]

[Patent Document 1] Japanese Patent Laid-Open No. 58-206078

[Patent Document 2] Japanese Patent Laid-Open No. 60-23973

[Patent Document 3] JP-A-61-227377

[Patent Document 4] JP-A-61-284070

[Patent Document 5] Japanese Unexamined Patent Publication No. 4-184870

[Patent Document 6] JP-A-8-88023

[Patent Document 7] Japanese Patent Laid-Open No. 11-67267

[Patent Document 8] Japanese Patent Laid-Open No. 11-260401

[Patent Document 9] Japanese Patent Application Laid-Open No. 2000-12080

[0012]

The present invention has been made to solve the above problems, and is flame-retardant (self-extinguishing), has high conductivity, and is electrochemically stable. The present invention aims to provide a non-aqueous electrolyte solution for a lithium secondary battery. Another object of the present invention is to provide a lithium secondary battery using this non-aqueous electrolyte solution, which has excellent charge / discharge characteristics and has both safety and reliability.

[0013]

Means for Solving the Problems As a result of intensive studies in view of such circumstances, the present inventors have found that a lithium salt is dissolved in a non-aqueous solvent containing a phosphoric acid ester or a phosphoric acid ester and a cyclic carboxylic acid ester to obtain vinylene. By adding a carbonate compound and / or a vinylethylene carbonate compound, and further adding a cyclic amide compound and / or a cyclic carbamate compound and / or a cyclic hetero compound, it has flame retardancy (self-extinguishing property) and conductivity. , And an electrolytic solution with excellent electrochemical stability are obtained, and in the secondary battery using this non-aqueous electrolytic solution, a secondary battery with extremely high safety is realized with excellent battery charge / discharge characteristics. They have found that they can do so and have completed the present invention.

The present invention is a non-aqueous electrolyte for a lithium secondary battery, which is used in combination with a positive electrode and a negative electrode capable of inserting and extracting lithium, wherein (1) a non-aqueous solvent containing a phosphoric acid ester, 2) a lithium salt dissolved in the non-aqueous solvent, (3) a vinylene carbonate compound and / or a vinylethylene carbonate compound, and (4) a formula (I):

[0015]

[Chemical 14]

(In the formula, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group. And R ² is a divalent hydrocarbon group having 2 to 8 carbon atoms), and / or formula (II):

[0017]

[Chemical 15]

(In the formula, R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group. And R ⁴ is a divalent hydrocarbon group having 2 to 8 carbon atoms) and / or the formula (III):

[0019]

[Chemical 16] (In the formula, R ⁵ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group, R ⁶ is a divalent hydrocarbon group having 2 to 8 carbon atoms), and provides a non-aqueous electrolyte solution characterized by containing a cyclic hetero compound.

Further, the present invention is the above-mentioned non-aqueous electrolytic solution, wherein the non-aqueous solvent further contains a cyclic carboxylic acid ester. Furthermore, the present invention provides a lithium secondary battery using these non-aqueous electrolytes. The present invention also provides a cyclic amide compound represented by the above formula (I), and / or a cyclic carbamate compound represented by the above formula (II),
And / or the cyclic hetero compound represented by the formula (III) is 0.1 to 15% by weight based on the total weight of the non-aqueous electrolyte solution.
Is a non-aqueous electrolyte solution.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. [Non-Aqueous Electrolyte Solution] The non-aqueous electrolyte solution of the present invention comprises a non-aqueous solvent containing a phosphoric acid ester (a), a lithium salt dissolved therein, and a vinylene carbonate compound and / or a vinyl ethylene carbonate compound (c) added thereto. Further, a cyclic amide compound of the formula (I), and / or a cyclic carbamate compound of the general formula (II), and / or a cyclic hetero compound (d) of the general formula (III) are added.

In the present invention, the phosphoric acid ester (a) contained in the non-aqueous solvent may be a chain phosphoric acid ester, a cyclic phosphoric acid ester, or a combination thereof. The chain phosphoric acid ester is preferably trialkyl phosphate having an alkyl group having 1 to 4 carbon atoms, and particularly preferably the compound represented by the formula (IV):

[0023]

[Chemical 17]

(In the formula, R ^{7 to} R ⁹ are each independently
It is an unsubstituted or fluorine-substituted linear or branched alkyl group having 1 to 4 carbon atoms).

The cyclic phosphoric acid ester has the formula (V):

[0026]

[Chemical 18]

(In the formula, R ¹⁰ is an unsubstituted or fluorine-substituted straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ¹¹ is straight-chain alkyl group having 2 to 8 carbon atoms. Or a branched alkylene group).

In the chain phosphoric ester of formula (IV),
R⁷~ R⁹Is an alkyl group, for example, a methyl group,
Cyl group, propyl group and butyl group can be mentioned.
In the case of a substituted alkyl group, for example, trifluoroethyl
Group, pentafluoropropyl group, hexafluoroisop
Examples include a ropyl group and a heptafluorobutyl group. R
⁷, R⁸And R⁹The total number of carbon atoms contained in is preferably 3 to 7.
Good

As the chain phosphoric acid ester of the formula (IV),
For example, trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, dimethylpropyl phosphate, dimethylbutyl phosphate, diethylmethyl phosphate, dipropylmethyl phosphate, dibutylmethyl phosphate, methylethylpropyl phosphate, methylethyl phosphate. Butyl, methyl propyl butyl phosphate, etc. are mentioned.

Among the chain phosphoric acid esters of the formula (IV), those having a fluorine-substituted alkyl group include, for example, trifluoroethyldimethyl phosphate, bis (trifluoroethyl) methyl phosphate and trisphosphate. (Trifluoroethyl), pentafluoropropyldimethyl phosphate, heptafluorobutyldimethyl phosphate, trifluoroethylmethylethyl phosphate, pentafluoropropylmethylethyl phosphate, heptafluorobutylmethylethyl phosphate, trifluoroethylmethyl phosphate Propyl,
Pentafluoropropylmethylpropyl phosphate, heptafluorobutylmethylpropyl phosphate, trifluoroethylmethylbutyl phosphate, pentafluoropropylmethylbutyl phosphate, heptafluorobutylmethylbutyl phosphate, trifluoroethyldiethylphosphate, pentaphosphate Fluoropropyl diethyl, heptafluorobutyldiethyl phosphate, trifluoroethylethylpropyl phosphate, pentafluoropropylethylpropyl phosphate, heptafluorobutylethylpropyl phosphate, trifluoroethylethylbutyl phosphate, pentafluoropropylethylbutyl phosphate , Heptafluorobutylethyl butyl phosphate, trifluoroethyl dipropyl phosphate, pentafluoropropyl dipropyl phosphate, heptafluorobutyl diphosphate Pills, trifluoroethyl propyl butyl phosphate, pentafluoropropyl propyl butyl phosphate, heptafluorobutyl propyl butyl phosphate,
Examples thereof include trifluoroethyl dibutyl phosphate, pentafluoropropyl dibutyl phosphate, and heptafluorobutyl dibutyl phosphate.

Among these, trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, dimethylpropyl phosphate, methyldiethyl phosphate, trifluoroethyldimethyl phosphate, pentafluoropropyldimethyl phosphate, trifluoroethylmethyl phosphate. Ethyl, pentafluoropropylmethylethyl phosphate, trifluoroethylmethylpropyl phosphate, pentafluoropropylmethylpropyl phosphate are preferable, and trimethyl phosphate is particularly preferable.
Trifluoroethyldimethyl phosphate, bis (trifluoroethyl) methyl phosphate, and tris (trifluoroethyl) phosphate are preferred.

In the cyclic ester of formula (V), R
Examples of ¹⁰ include a methyl group, an ethyl group, a propyl group, a butyl group, a trifluoroethyl group, a pentafluoropropyl group, a hexafluoroisopropyl group and a heptafluorobutyl group. Of these, a methyl group and an ethyl group are preferable.

R ¹¹ is, for example, ethylene group, propylene group, trimethylene group, butylene group, tetramethylene group, 1,1-dimethylethylene group, pentamethylene group,
Examples include 1,1,2-trimethylethylene group, hexamethylene group, tetramethylethylene group, heptamethylene group, octamethylene group and the like. Among these, ethylene group is preferable.

As the cyclic phosphate of the formula (V),
For example, ethylene methyl phosphate, ethylene ethyl phosphate,
Ethylene-n-propyl phosphate, ethylene isopropyl phosphate, ethylene-n-butyl phosphate, ethylene-sec-butyl phosphate, ethylene-t-butyl phosphate, propylene methyl phosphate, propylene ethyl phosphate, propylene phosphate -N-propyl, propylene isopropyl phosphate, propylene-n-butyl phosphate, propylene-sec-butyl phosphate, propylene-t-butyl phosphate, trimethylene methyl phosphate, trimethylene ethyl phosphate, trimethylene phosphate- n-Propyl, trimethylene isopropyl phosphate, trimethylene-n-butyl phosphate, trimethylene-sec-butyl phosphate, trimethylene-phosphate
t-butyl, butylene methyl phosphate, butylene ethyl phosphate, butylene-n-propyl phosphate, butylene isopropyl phosphate, butylene-n-butyl phosphate, butylene-sec-butyl phosphate, butylene-t-butyl phosphate. ,
Isobutylene methyl phosphate, isobutylene ethyl phosphate, isobutylene-n-butyl phosphate, isobutylene-sec-butyl phosphate, isobutylene-t-butyl phosphate, tetramethylene methyl phosphate, tetramethylene ethyl phosphate, tetramethylene phosphate -N-propyl, tetramethylene isopropyl phosphate, tetramethylene-n-butyl phosphate, tetramethylene-sec-butyl phosphate,
Tetramethylene-t-butyl phosphate, pentamethylene methyl phosphate, pentamethylene ethyl phosphate, pentamethylene-n-propyl phosphate, pentamethylene isopropyl phosphate, pentamethylene-n-butyl phosphate, pentamethylene phosphate sec-Butyl, pentamethylene-t-butyl phosphate, trimethylethylenemethyl phosphate, trimethylethyleneethyl phosphate, trimethylethylene-n-propyl phosphate, trimethylethyleneisopropyl phosphate, trimethylethylene-n-butyl phosphate, phosphorus Acid trimethylethylene-sec-butyl phosphate, trimethylethylene-t-butyl phosphate, hexamethylenemethyl phosphate,
Hexamethylene ethyl phosphate, hexamethylene phosphate-
n-propyl, hexamethylene isopropyl phosphate, hexamethylene-n-butyl phosphate, hexamethylene-sec-butyl phosphate, hexamethylene-t-butyl phosphate, tetramethylethylenemethyl phosphate, tetramethylethyleneethyl phosphate , Tetramethylethylene phosphate
n-Propyl, tetramethylethylene isopropyl phosphate, tetramethylethylene-n-butyl phosphate, tetramethylethylene-sec-butyl phosphate, tetramethylethylene-t-butyl phosphate, heptamethylenemethyl phosphate, heptaphosphate Methylene ethyl, heptamethylene-n-propyl phosphate, heptamethylene isopropyl phosphate, heptamethylene-n-butyl phosphate, heptamethylene-sec-butyl phosphate, heptamethylene phosphate-t-
Butyl, octamethylene methyl phosphate, octamethylene ethyl phosphate, octamethylene-n-propyl phosphate,
Examples include octamethylene isopropyl phosphate, octamethylene-n-butyl phosphate, octamethylene-sec-butyl phosphate, octamethylene-t-butyl phosphate and the like. Among these, ethylene methyl phosphate and ethylene ethyl phosphate are preferable.

Among the cyclic phosphates of formula (VI), those having a fluorine-substituted alkyl group include
For example, ethylene trifluoroethyl phosphate, ethylene pentafluoropropyl phosphate, ethylene hexafluoroisopropyl phosphate, ethylene heptafluorobutyl phosphate, propylene trifluoroethyl phosphate, propylene pentafluoropropyl phosphate, propylene hexafluoroisopropyl phosphate, Propylene heptafluorobutyl phosphate, trimethylene trifluoroethyl phosphate, trimethylene pentafluoropropyl phosphate, trimethylene hexafluoroisopropyl phosphate, trimethylene heptafluorobutyl phosphate, butylene trifluoroethyl phosphate, butylene pentaphosphate Fluoropropyl, butylene hexafluoroisopropyl phosphate, butylene heptafluorobutyl phosphate, tetramethylene trifluoroethyl phosphate , Tetramethylene pentafluoropropyl phosphate, tetramethylene hexafluoroisopropyl phosphate, tetramethylene heptafluorobutyl phosphate, dimethylethylene trifluoroethyl phosphate, dimethylethylene pentafluoropropyl phosphate, dimethylethylene hexafluoroisopropyl phosphate, phosphorus Dimethyl ethylene heptafluorobutyl phosphate, pentamethylene trifluoroethyl phosphate, pentamethylene pentafluoropropyl phosphate, pentamethylene hexafluoroisopropyl phosphate, pentamethylene heptafluorobutyl phosphate, trimethylethylene trifluoroethyl phosphate, trimethyl phosphate Ethylene pentafluoropropyl, trimethylethylene hexafluoroisopropyl phosphate, trimethylethylene heptaphosphate Fluorobutyl, hexamethylene trifluoroethyl phosphate, hexamethylene pentafluoropropyl phosphate, hexamethylene hexafluoroisopropyl phosphate, hexamethylene heptafluorobutyl phosphate, tetramethylethylene trifluoroethyl phosphate, tetramethylethylene pentaphosphate Fluoropropyl, tetramethylethylene hexafluoroisopropyl phosphate, tetramethylethylene heptafluorobutyl phosphate, heptamethylene trifluoroethyl phosphate, heptamethylene pentafluoropropyl phosphate, heptamethylene hexafluoroisopropyl phosphate, heptamethylene heptaphosphate Fluorobutyl,
Examples include octamethylene trifluoroethyl phosphate, octamethylene pentafluoropropyl phosphate, octamethylene hexafluoroisopropyl phosphate, octamethylene heptafluorobutyl phosphate and the like. Among these, ethylene trifluoroethyl phosphate is preferable.

The phosphoric acid ester may be used alone or in admixture of two or more kinds.

The non-aqueous electrolytic solution of the present invention is prepared by dissolving a lithium salt in a non-aqueous solvent containing a phosphoric acid ester (a) and a cyclic carboxylic acid ester (b) to obtain a vinylene carbonate compound and / or vinylethylene carbonate. Compound (c) is added, and a cyclic amide compound of formula (I) is added,
And / or the cyclic carbamate compound of the general formula (II) and / or the cyclic hetero compound (d) of the general formula (III) are added.

In this case, (a) phosphoric acid ester and (b)
It is preferable that the component (a) is 10% by volume or more and less than 100% by volume, and the component (b) is 0% by volume or more and 90% by volume or less based on 100% by volume of the total amount of the cyclic carboxylic acid ester. More preferably, the component (a) is 15 to 95.
The content of the component (b) is 85 to 5% by volume, more preferably the content of the component (a) is 20 to 90% by volume, and the content of the component (b) is 80 to 10% by volume.

The cyclic carboxylic acid ester of the component (b) is
For example, γ-butyrolactone, γ-valerolactone, γ-
Examples thereof include caprolactone, γ-octanolactone, β-butyrolactone, δ-valerolactone, and ε-caprolactone. These may be used alone or in combination of two or more. In particular, γ-butyrolactone, δ
-Valerolactone and ε-caprolactone are preferred.

The non-aqueous solvent of the present invention is preferably a non-aqueous solvent composed of a phosphoric acid ester (a) or a non-aqueous solvent composed of a phosphoric acid ester (a) and a cyclic carboxylic acid ester (b). The non-aqueous solvent may further contain other organic solvent that has been conventionally used in the electrolytic solution for lithium secondary batteries within a range that does not impair the flame retardancy of the non-aqueous electrolytic solution. The term "flame retardancy" as used herein means that a glass fiber filter paper having a width of 15 mm, a length of 300 mm, and a thickness of 0.19 mm is impregnated into a beaker containing an electrolytic solution for 10 minutes or more. After sufficiently impregnating the electrolytic solution, one end of the glass fiber filter paper is sandwiched by clips and hung vertically, and heated from this lower end with a small gas flame of a lighter for about 3 seconds, and the self-extinguishing property is maintained with the fire source removed. It will be expressed.

As these solvents, cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate;
Chain carboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, ethyl propionate; 1,2-
Chain ethers such as dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-dipropoxyethane; tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 2,5- Cyclic ethers such as dimethyltetrahydrofuran and tetrahydropyran; dimethylformamide,
Amides such as dimethylacetamide; dimethyl sulfite,
Examples include sulfites such as diethyl sulfite, ethylene sulfite, and propylene sulfite; sulfates such as dimethyl sulfate, diethyl sulfate, ethylene sulfate, and propylene sulfate; sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide; acetonitrile, propionitrile, and the like. . These may be used alone or in combination of two or more. Of these, ethylene carbonate and propylene carbonate are preferred. These are 40% of the total volume of non-aqueous solvent.
It is preferably less than 3% by volume, more preferably 3
Less than 0% by volume, more preferably less than 20% by volume,
It is particularly preferably less than 10% by volume. It should be noted that non-flammable or flame-retardant solvents such as halogen-based carbonic acid esters, carboxylic acid esters, ethers and other halogen-based solvents, room temperature molten salts such as imidazolium salts and pyridinium salts, and phosphazene-based solvents are non-aqueous solvents. Can be included in.

In the above volume ratio, the value measured at 25 ° C. is used as the volume ratio of each component. For a solid substance at room temperature, a value measured in a molten state by heating to the melting point is used.

In the non-aqueous electrolyte solution of the present invention, the solute solution
As lithium, LiPF₆, LiBF_FourNothing selected from
Organic acid lithium salt or LiCF₃SO₃, LiN (CF₃
SO ₂)₂, LiN (C₂F_FiveSO₂)₂, LiN (CF₃S
O₂) (C_FourF₉SO₂), LiPF₃(C₂F_Five)₃, LiB
(CF₃COO)_FourOrganic acid lithium selected from the group consisting of
Mumu salt and the like can be used. Using these salts
To obtain an electrolyte with high conductivity and electrochemically excellent
And has excellent charge / discharge capacity and charge / discharge cycle characteristics.
Battery can be obtained.

The lithium salt is dissolved in the non-aqueous electrolyte solution.
Quality concentration is usually 0.5-2mol / dm ³, Preferably 0.
5 to 1.5 mol / dm³Use within the range. Lithium salt
If the solute concentration of is within this range, it has favorable conductivity.
A non-aqueous electrolyte solution is obtained.

The non-aqueous electrolytic solution of the present invention comprises a vinylene carbonate compound and / or a vinylethylene carbonate compound (c) in a non-aqueous solvent in which the above lithium salt is dissolved.
And further add a cyclic amide compound represented by the formula (I), and / or a cyclic carbamate compound represented by the formula (II), and / or a cyclic hetero compound (d) represented by the general formula (III). It was done. By adding these, it is possible to improve the charge and discharge characteristics (charge and discharge efficiency, charge and discharge capacity) of the battery using the non-aqueous electrolyte solution.

Among the component (c), the vinylene carbonate compounds include, for example, vinylene carbonate, 4-methylvinylene carbonate, 4-ethylvinylene carbonate, 4,5-dimethylvinylene carbonate and 4,5-dimethylvinylene carbonate.
Diethyl vinylene carbonate, and 4-methyl-5-
Examples thereof include ethyl vinylene carbonate, and these can be used alone or in combination of two or more. Of these, vinylene carbonate is preferred.

In the component (c), the vinyl ethylene carbonate compound is, for example, 4-vinyl ethylene carbonate, 4-vinyl-4-methyl ethylene carbonate, 4-vinyl-4-ethyl ethylene carbonate, 4
-Vinyl-4-n-propyl ethylene carbonate, 4
-Vinyl-5-methylethylene carbonate, 4-vinyl-5-ethylethylene carbonate, 4-vinyl-5
Examples thereof include -n-propylethylene carbonate, and these may be used alone or in combination of two or more. Among these, 4-vinylethylene carbonate and 4-vinyl-4-methylethylene carbonate are preferable, and 4-vinylethylene carbonate is particularly preferable.

As the component (c), a vinylene carbonate compound and a vinylethylene carbonate compound may be used alone, or two or more of them may be used in combination. The addition amount of the vinylene carbonate compound and / or the vinyl ethylene carbonate compound used in the present invention is preferably 0.1 to 15% by weight, more preferably 0.1% by weight, based on the total weight of the non-aqueous electrolyte solution. 5 to 12% by weight, especially 1.0 to 1
0% by weight is preferred.

Formula (I) of component (d):

[0050]

[Chemical 19]

(In the formula, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group. And R ² is a divalent hydrocarbon group having 2 to 8 carbon atoms), R ¹ is, for example, a straight chain or branched chain having 1 to 4 carbon atoms. Alkyl group, vinyl group or allyl group,
Or an aryl group or an aralkyl group having 6 to 8 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, a tert-butyl group. And among these, the methyl group,
The ethyl group is preferred. When R ¹ is a cycloalkyl group having 6 to 8 carbon atoms, a cyclohexyl group can be mentioned. R ²
Is a linear or branched alkylene group having 2 to 8 carbon atoms, for example, ethylene group, propylene group, trimethylene group, butylene group, tetramethylene group, 1,1-dimethylethylene group, pentamethylene group, It is a 1,1,2-trimethylethylene group, a hexamethylene group, a tetramethylethylene group, a heptamethylene group, an octamethylene group and the like, and among these, an ethylene group, a trimethylene group, a tetramethylene group and a pentamethylene group are preferable.

Specific examples of the cyclic amide compound of the formula (I) include 1-methyl-2-pyrrolidone and 1-ethyl-2-
Pyrrolidone, 1-n-propyl-2-pyrrolidone, 1-
Isopropyl-2-pyrrolidone, 1-n-butyl-2-
Pyrrolidone, 1-vinyl-2-pyrrolidone, 1-allyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, 1-phenyl-2-pyrrolidone, 1-benzyl-2
-Compounds having a pyrrolidone skeleton such as pyrrolidone; 1-
Methyl-2-piperidone, 1-ethyl-2-piperidone, 1-n-propyl-2-piperidone, 1-isopropyl-2-piperidone, 1-n-butyl-2-piperidone, 1-vinyl-2-piperidone, 1-allyl-2-piperidone, 1-cyclohexyl-2-piperidone, 1-
Compounds having a piperidone skeleton such as phenyl-2-piperidone and 1-benzyl-2-piperidone; 1-methyl-
2-caprolactam, 1-ethyl-2-caprolactam, 1-n-propyl-2-caprolactam, 1-isopropyl-2-caprolactam, 1-n-butyl-2-
Caprolactam, 1-vinyl-2-caprolactam, 1
-Allyl-2-caprolactam, 1-cyclohexyl-
Examples thereof include compounds having a caprolactam skeleton such as 2-caprolactam, 1-phenyl-2-caprolactam and 1-benzyl-2-caprolactam. These may be used alone or in combination of two or more.

Specific examples of preferred cyclic amide compounds include 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone and 1-allyl-.
2-pyrrolidone, 1-methyl-2-piperidone, 1-ethyl-2-piperidone, 1-methyl-2-caprolactam and 1-ethyl-2-caprolactam. Particularly preferred cyclic amide compounds are 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone and 1-vinyl-
They are 2-pyrrolidone, 1-allyl-2-pyrrolidone, 1-methyl-2-caprolactam and 1-ethyl-2-caprolactam.

Formula (II) of component (d):

[0055]

[Chemical 20]

(In the formula, R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group. And R ⁴ is a divalent hydrocarbon group having 2 to 8 carbon atoms), R ³ is, for example, a linear or branched C 1 to 4 carbon atom. Examples thereof include an alkyl group, a vinyl group or an allyl group, or an aryl group or an aralkyl group having 6 to 8 carbon atoms, and specifically, a methyl group, an ethyl group, n-
A propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group, and among these, a methyl group and an ethyl group are preferable. When R ³ is a cycloalkyl group having 6 to 8 carbon atoms, a cyclohexyl group can be mentioned. Further, R ⁴ includes a linear or branched alkylene group having 2 to 8 carbon atoms, for example, an ethylene group, a propylene group, a trimethylene group, a butylene group, a tetramethylene group, a 1,1-dimethylethylene group, Pentamethylene group,
Examples include 1,1,2-trimethylethylene group, hexamethylene group, tetramethylethylene group, heptamethylene group, octamethylene group and the like. Among these, ethylene group is preferable.

Specific examples of the cyclic carbamate compound of the formula (II) include 3-methyl-2-oxazolidone, 3-ethyl-2-oxazolidone, 3-n-propyl-2-oxazolidone and 3-isopropyl-2-oxazolidone. , 3-n-butyl-2-oxazolidone, 3-vinyl-2-oxazolidone, 3-allyl-2-oxazolidone, 3-cyclohexyl-2-oxazolidone, 3-phenyl-2-oxazolidone, 3-benzyl-2-oxazolidone And other compounds having an oxazolidone skeleton. These may be used alone or in combination of two or more.

Specific examples of preferred cyclic carbamate compounds include 3-methyl-2-oxazolidone, 3-ethyl-2-oxazolidone, 3-vinyl-2-oxazolidone and 3-allyl-2-oxazolidone.
-Methyl-2-oxazolidone and 3-ethyl-2-oxazolidone are particularly preferred.

Formula (III) of component (d):

[0060]

[Chemical 21]

(In the formula, R ⁵ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group. And R ⁶ is a divalent hydrocarbon group having 2 to 8 carbon atoms), and R ⁵ is, for example, a straight chain or branched chain having 1 to 4 carbon atoms. Examples thereof include an alkyl group, a vinyl group or an allyl group, or an aryl group or an aralkyl group having 6 to 8 carbon atoms, and specifically, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, sec-butyl group, t
It is an ert-butyl group, and among these, a methyl group and an ethyl group are preferable. When R ⁵ is a cycloalkyl group having 6 to 8 carbon atoms, a cyclohexyl group can be mentioned. Also, R
⁶ includes a linear or branched alkylene group having 2 to 8 carbon atoms, for example, ethylene group, propylene group, trimethylene group, butylene group, tetramethylene group, 1,1-
Dimethylethylene group, pentamethylene group, 1,1,2-
Trimethylethylene group, hexamethylene group, tetramethylethylene group, heptamethylene group, octamethylene group,
It is a phenylene group or the like, and among these, an ethylene group is preferable. Further, R ⁶ is a linear or branched alkenylene group having 2 to 8 carbon atoms, and among these, a vinylene group is preferable. Further, R ⁶ includes a substituted or unsubstituted phenylene group.

The cyclic hetero compound of the formula (III) is, for example, N-methyl-succinimide, N-ethyl-succinimide, Nn-propyl-succinimide, N-isopropyl-succinimide or N-isopropyl-succinimide. -N-butyl-succinimide, N-vinyl-succinimide, N-allyl-succinimide, N-cyclohexyl-succinimide, N
Compounds having a succinimide skeleton such as -phenyl-succinimide, N-benzyl-succinimide; N-methyl-phthalimide, N-ethyl-phthalimide, N-
n-propyl-phthalimide, N-isopropyl-phthalimide, N-n-butyl-phthalimide, N-vinyl-phthalimide, N-allyl-phthalimide, N-cyclohexyl-phthalimide, N-phenyl-phthalimide, N-benzyl-phthalimide, etc. A compound having a phthalimide skeleton; N-methyl-maleimide, N-ethyl-maleimide, Nn-propyl-maleimide, N-isopropyl-maleimide, Nn-butyl-maleimide, N-vinyl-maleimide, N-allyl. -Maleimide, N-cyclohexyl-maleimide, N-phenyl-
Examples thereof include compounds having a maleimide skeleton such as maleimide and N-benzyl-maleimide. These may be used alone or in combination of two or more.

Specific examples of preferred cyclic hetero compounds include N-methyl-succinimide, N-ethyl-succinimide, N-vinyl-succinimide and N-allyl-.
Examples include succinimide, N-methyl-phthalimide, N-ethyl-phthalimide, N-vinyl-phthalimide, N-allyl-phthalimide, N-methyl-maleimide and N-ethyl-maleimide, and N-methyl-succinimide. , N-ethyl-succinimide, N-methyl-phthalimide and N-ethyl-phthalimide are particularly preferred.

As the component (d), the cyclic amide compound of the formula (I), the cyclic carbamate compound of the formula (II) and the cyclic hetero compound of the formula (III) can be used alone, respectively, but two or more kinds of them can be used. Can also be used in combination. The cyclic amide compound represented by the formula (I), and / or the cyclic carbamate compound represented by the formula (II), and / or the cyclic hetero compound represented by the formula (III) are relative to the total weight of the non-aqueous electrolyte solution. It is preferably 0.1 to 15% by weight, more preferably 0.5 to 12% by weight, and particularly preferably 1.0 to 10% by weight.

[Lithium Secondary Battery] The lithium secondary battery of the present invention is configured by combining the above non-aqueous electrolyte solution with a negative electrode and a positive electrode.

The negative electrode constituting the battery is not particularly limited as long as it contains a material capable of inserting and extracting lithium as a negative electrode material. A known carbonaceous material can be preferably used as the negative electrode material, and examples thereof include cokes, glassy carbons, artificial graphite, natural graphite, non-graphitizable carbons, pyrolytic carbons and carbon fibers.

Of these, preferred are artificial graphite and purified natural graphite produced by high-temperature heat treatment of graphitizable pitch obtained from various raw materials, and graphite obtained by subjecting these graphite to various surface treatments including pitch. It is a material. In these graphite materials, the d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method is 0.335 to
0.34 nm is preferable, more preferably 0.335 to
It is 0.337 nm. The ash content of these graphite materials is preferably 1% by weight or less, more preferably 0.5% by weight or less, and particularly preferably 0.1% by weight or less, based on the total weight of the graphite materials. The crystallite size (Lc) determined by X-ray diffraction by Gakshin method is preferably 30 nm or more, more preferably 50 nm or more, and particularly preferably 100 nm or more. Also, the median diameter of graphite material is
The median diameter by the scattering method is 1 μm to 100 μm, preferably 3 μm to 50 μm, more preferably 5 μm to 40 μm,
Particularly preferably, it is 7 μm to 30 μm. BE of graphite material
T method specific surface area was 0.5m ² /g~25.0m ² / g, preferably 0.7m ² /g~20.0m ² / g, more preferably 1.0m ² / g~15. 0 m ² / g, particularly preferably 1.5m ² /g~10.0m ² / g. Further, in the Raman spectrum analysis using argon ion laser light, the intensity ratio of the peaks in the range of 1580~1620cm ^-1 PA (peak intensity IA) and the range of 1350 ^-1 peak PB (peak intensity IB) R = IB / IA
There is a 0 to 0.5, the half-value width of the peak in the range of 1580～1620Cm ^-1 is 26cm ^-1 or less, more preferably 25
cm ^-1 or less.

These carbonaceous materials may be used alone or as a mixture of two or more kinds, and these carbonaceous materials may be mixed with the following other negative electrode materials capable of absorbing and releasing lithium. It can also be used.

As the negative electrode material other than carbonaceous material capable of inserting and extracting lithium, Ag, Zn, Al, Ga and I are used.
n, Si, Ge, Sn, Pb, Ge, Sn, Pb, P,
An alloy of at least one selected from metals such as Sb, Bi, Cu, Ni, Sr, and Ba with lithium; Ag, Zn, Al,
Ga, In, Si, Ge, Sn, Pb, Ge, Sn, P
An oxide of at least one metal selected from metals such as b, P, Sb, Bi, Cu, Ni, Sr, and Ba; lithium metal can be used. Among them, 1 selected from Sn, Si and Al
Alloys of one or more metals with lithium; Sn, Si and Al
An oxide of one or more metals selected from the following; lithium metal is preferred. Note that Sn, Si, and Al can be used as a negative electrode material as a simple metal or as an oxide of an alloy of these metals and lithium. These negative electrode materials may be used alone or in combination of two or more.

As the shape of the negative electrode, a sheet electrode coated on a current collector after being mixed with a binder and a conductive agent as necessary, a pellet electrode subjected to press molding, and the like can be used.

As the current collector for the negative electrode, a metal such as copper, nickel or stainless is used, and among them, a copper foil is preferable from the viewpoints of being easily processed into a thin film and cost.

As the positive electrode material constituting the battery, a material capable of inserting and extracting lithium such as lithium transition metal composite oxide material such as lithium manganese oxide, lithium cobalt oxide and lithium nickel oxide can be used. ,
The above-mentioned lithium-transition metal composite oxide is preferable.

The shape of the positive electrode is not particularly limited, and for example,
If necessary, a binder, a thickener, a conductive material, a solvent, etc. are added to the positive electrode material, mixed, and then applied to a substrate of a current collector and dried, and a sheet electrode or a press-formed pellet electrode is used. can do.

The collector for the positive electrode is made of aluminum, titanium,
A metal such as tantalum or an alloy thereof is used. Among these, aluminum or its alloy is particularly preferable in terms of energy density because it is lightweight.

The shape of the battery of the present invention is not particularly limited,
For example, a cylinder type battery or a coin type battery can be used. A cylinder type battery can be manufactured by spirally forming the above-mentioned negative electrode and positive electrode as sheet electrodes and a porous separator made of a material such as polyolefin, injecting the above-mentioned electrolytic solution, and then sealing. A coin type battery can be manufactured by stacking the above-mentioned negative electrode and positive electrode, which are used as pellet electrodes, and a separator. A porous sheet or non-woven fabric made of polyolefin such as polyethylene or polypropylene can be used as the separator constituting the battery.

[0076]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

[Non-Aqueous Electrolyte] Examples 1 to 9 and Comparative Examples 1 to 4 Solutes and additives shown in Table 1 were dissolved in the non-aqueous mixed solvent shown in Table 1 to give a solute concentration of 1 mol / dm. An electrolyte solution of ³ was prepared. Next, the self-extinguishing property (flame retardancy) and the electrical conductivity of this electrolytic solution were measured. The results are shown in Table 2.

[0078]

[Table 1]

The abbreviations in the table indicate the following. TMP: Trimethyl phosphate EDMP: Dimethyl ethyl phosphate DIMP: Diethyl methyl phosphate TFEDMP: Trifluoroethyl dimethyl phosphate GBL: γ-butyrolactone EC: Ethylene carbonate DEC: Diethyl carbonate VC: Vinylene carbonate VEC: 4-vinyl ethylene carbonate NMP: 1-methyl-2-pyrrolidone NVP: 1-vinyl-2-pyrrolidone NMC: 1-methyl-2-caprolactam NMO: 3-methyl-2-oxazolidone NMS: N-methyl-succinimide NMM: N-methyl-maleimide

The self-extinguishing property evaluation and the conductivity measurement of the non-aqueous electrolyte solution were carried out as follows. Evaluation of self-extinguishing property of non-aqueous electrolyte: width 15mm, length 300
A rectangular glass fiber filter paper having a thickness of 0.19 mm and a thickness of 0.19 mm was immersed in a beaker containing an electrolytic solution for 10 minutes or more to sufficiently impregnate the glass fiber filter paper with the non-aqueous electrolytic solution. Next, excess non-aqueous electrolyte solution adhering to the glass fiber filter paper was removed at the beaker edge, and one end of the glass fiber filter paper was sandwiched with a clip and suspended vertically. From this lower end, a small gas flame of a lighter was heated for about 3 seconds, and the presence or absence of self-extinguishing property in the state where the fire source was removed and the time until extinguishing the fire were measured.

Measurement of conductivity of non-aqueous electrolyte: conductivity meter CM-30S and conductivity cell CG manufactured by Toa Denpa Kogyo Co., Ltd.
The electrical conductivity at 25 ° C. was measured using −511B.

[Production of Battery] Examples 1 to 9 and Comparative Examples 1 to 1
A coin-type battery was produced using the non-aqueous electrolyte solution of No. 4. The negative electrode of the battery was manufactured as follows. A current collector was prepared by mixing natural graphite as a negative electrode material with a fluororesin as a binder in a weight ratio of 90:10 and dispersing this in a solvent (N-methylpyrrolidone) to form a slurry. It was applied to a copper foil as a body and dried to obtain a negative electrode sheet. The obtained negative electrode sheet was punched out into a negative electrode having a diameter of 12.5 mm. Fluorine resin as a binder, weight ratio 90: 1
The mixture was mixed at a ratio of 0, and this was dispersed in a solvent (N-methylpyrrolidone) to form a slurry, which was applied to a copper foil as a current collector and dried to obtain a negative electrode sheet. The obtained negative electrode sheet was punched out into a negative electrode having a diameter of 12.5 mm.

The positive electrode was manufactured as follows. Lithium nickel cobalt oxide (Li
Ni _0.8 Co _0.2 O ₂ ) with acetylene black as a conductive agent and fluororesin as a binder in a weight ratio of 9
The mixture was mixed at 0: 5: 5, and this was dispersed in N-methylpyrrolidone to form a slurry, which was applied to an aluminum foil as a current collector and dried to obtain a positive electrode sheet. The obtained positive electrode sheet was punched out into a positive electrode with a diameter of 12.5 mm.

The battery was obtained by impregnating the positive electrode and the negative electrode obtained as described above with the non-aqueous electrolyte obtained by Examples 1 to 9 and Comparative Examples 1 to 5 in a stainless steel case which also served as a positive electrode terminal. The thus-obtained porous polypropylene film was housed via a separator and sealed with a stainless steel sealing plate serving also as a negative electrode terminal via a polypropylene gasket to prepare a coin-type battery, and its charge / discharge characteristics were measured. The results are shown in Table 2. Further, FIG. 1 shows the cycle characteristic results of the charge / discharge capacity retention rate of the batteries using the non-aqueous electrolyte solutions of Examples 1 and 8 and Comparative Example 3.

[0085]

[Table 2]

Measurement of charge / discharge characteristics of battery: Using the battery manufactured as described above, charging was performed by a 4.2V, 1.4mA constant current / constant voltage charging method, and was completed when 3 hours passed. did. The discharge is performed with a constant current of 1.4 mA, and the voltage is 2.
When the voltage reached 7V, the process was terminated. Through this charge / discharge cycle, the initial (first and third cycle) discharge capacity and charge / discharge efficiency of each battery were measured. Here, the charging / discharging efficiency is obtained from the following formula. Charge / discharge efficiency (%) = [(discharge capacity) / (charge capacity)] x
100

Cycle characteristics of discharge capacity maintenance rate: Further, charging and discharging were repeated to obtain cycle characteristics of discharge capacity maintenance rate. Here, the discharge capacity maintenance rate is obtained from the following equation. Discharge capacity maintenance rate (%) = [(nth discharge capacity) / (first charge capacity)] × 100 (n is the number of cycles)

As shown in Table 2 and FIG. 1, the electrolytic solution of the present invention has excellent flame retardancy and conductivity, and at the same time, excellent charge / discharge characteristics and cycle characteristics can be obtained.

[0089]

EFFECTS OF THE INVENTION The non-aqueous electrolyte solution of the present invention has self-extinguishing property (flame retardancy), good charge / discharge cycle characteristics can be obtained, and the battery has high safety and reliability. Has an excellent and unique effect.

[Brief description of drawings]

FIG. 1 is a diagram showing cycle characteristics of discharge capacity retention rate of coin type batteries manufactured using the electrolytic solutions prepared in Examples 1 and 8 and Comparative Example 3.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichi Ishigaki             3-3-1 Chuo 8-chome, Ami Town, Inashiki District, Ibaraki Prefecture             Mitsubishi Chemical Stock Association (72) Inventor Yasuyuki Shigematsu             3-3-1 Chuo 8-chome, Ami Town, Inashiki District, Ibaraki Prefecture             Mitsubishi Chemical Stock Association F term (reference) 5H029 AJ02 AJ06 AJ12 AK03 AL07                       AM03 DJ09 HJ01 HJ02

Claims (13)

[Claims] 1. A non-aqueous electrolyte solution for a lithium secondary battery, which is used in combination with a positive electrode and a negative electrode capable of inserting and extracting lithium, wherein (1) a non-aqueous solvent containing a phosphoric acid ester, and (2). A lithium salt dissolved in the non-aqueous solvent,
(3) vinylene carbonate compound and / or vinyl ethylene carbonate compound, and (4) formula (I): (In the formula, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group, R ² is a divalent hydrocarbon group having 2 to 8 carbon atoms), a cyclic amide compound represented by the formula (II): (In the formula, R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group, R ⁴ is a divalent hydrocarbon group having 2 to 8 carbon atoms), and a cyclic carbamate compound represented by the formula (III): (In the formula, R ⁵ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or a cycloalkyl group having 6 to 8 carbon atoms, an aryl group or an aralkyl group, R ⁶ is at least one selected from the group consisting of cyclic hetero compounds represented by C 2-8 divalent hydrocarbon groups). 2. A non-aqueous electrolyte solution for a lithium secondary battery, which is used in combination with a positive electrode and a negative electrode capable of inserting and extracting lithium, wherein (1) a non-aqueous solvent containing a phosphoric acid ester, and (2). A lithium salt dissolved in the non-aqueous solvent,
(3) vinylene carbonate compound and / or vinylethylene carbonate compound, and (4) formula (I): (In the formula, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, a cyclohexyl group, or an aryl group or aralkyl group having 6 to 8 carbon atoms; ² is a linear or branched alkylene group having 2 to 8 carbon atoms), a cyclic amide compound represented by the formula (II): (In the formula, R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, a cyclohexyl group, or an aryl group or aralkyl group having 6 to 8 carbon atoms; ⁴ is a linear or branched alkylene group having 2 to 8 carbon atoms), and a cyclic carbamate compound represented by the formula (III): (In the formula, R ⁵ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, a cyclohexyl group, or an aryl group or aralkyl group having 6 to 8 carbon atoms; ⁶ is a linear or branched alkylene group having 2 to 8 carbon atoms, a vinylene group, or a phenylene group), and contains at least one selected from the group consisting of cyclic hetero compounds. Claim 1
The non-aqueous electrolyte solution described. 3. A non-aqueous electrolyte solution for a lithium secondary battery, which is used in combination with a positive electrode and a negative electrode capable of inserting and extracting lithium, wherein (1) a non-aqueous solvent containing a phosphoric acid ester, and (2). A lithium salt dissolved in the non-aqueous solvent,
(3) vinylene carbonate compound and / or vinylethylene carbonate compound, and (4) formula (I): (In the formula, R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or an aryl group or aralkyl group having 6 to 8 carbon atoms, and R ²
Is a linear or branched alkylene group having 2 to 8 carbon atoms), a cyclic amide compound represented by the formula (II): (In the formula, R ³ is a linear or branched alkyl group having 1 to 4 carbon atoms, a vinyl group or an allyl group, or an aryl group or aralkyl group having 6 to 8 carbon atoms, and R ⁴
Is a linear or branched alkylene group having 2 to 8 carbon atoms), and a cyclic carbamate compound represented by the formula (II
I): (Wherein, R ⁵ is a linear or branched alkyl group, vinyl group or allyl group, or an aryl group or an aralkyl group having a carbon number of 6-8 having from 1 to 4 carbon atoms, R ⁶
Is a linear or branched alkylene group having 2 to 8 carbon atoms), and at least one selected from the group consisting of cyclic hetero compounds represented by the formula (1) is contained in the non-aqueous system. Electrolyte. 4. The non-aqueous electrolyte solution according to claim 1, wherein the non-aqueous solvent further contains a cyclic carboxylic acid ester. 5. The non-aqueous electrolyte solution according to claim 4, wherein the phosphoric acid ester is 10% by volume or more and less than 100% by volume with respect to the total volume of the phosphoric acid ester and the cyclic carboxylic acid ester. 6. The phosphoric acid ester has the general formula (IV): (In the formula, R ^{7 to} R ⁹ are each independently an unsubstituted or fluorine-substituted, straight-chain or branched alkyl group having 1 to 4 carbon atoms) , And / or formula (V): (In the formula, R ¹⁰ is unsubstituted or fluorine-substituted and has 1 to 1 carbon atoms.
4 is a straight-chain or branched alkyl group, and R ¹¹ is a straight-chain or branched alkylene group having 2 to 8 carbon atoms)
The non-aqueous electrolyte solution according to any one of claims 1 to 5, which is a cyclic phosphate ester represented by. 7. The phosphoric acid ester has the general formula (IV): (In the formula, R ^{7 to} R ⁹ are each independently an unsubstituted or fluorine-substituted, straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ⁷ , R ⁸ and R ⁹ Wherein the total number of carbon atoms contained in is 3 to 7), and / or formula (V): (In the formula, R ¹⁰ is unsubstituted or fluorine-substituted and has 1 to 1 carbon atoms.
4 is a straight-chain or branched alkyl group, and R ¹¹ is a straight-chain or branched alkylene group having 2 to 8 carbon atoms)
The non-aqueous electrolyte solution according to claim 6, which is a cyclic phosphate ester represented by. 8. The cyclic carboxylic acid ester is γ-butyrolactone, γ-valerolactone, γ-caprolactone,
The non-aqueous electrolyte solution according to any one of claims 4 to 7, which is at least one selected from the group consisting of γ-octanolactone, β-butyrolactone, δ-valerolactone, and ε-caprolactone. 9. The vinylene carbonate compound and / or
Alternatively, the vinyl ethylene carbonate compound comprises vinylene carbonate, 4-methylvinylene carbonate, 4-ethylvinylene carbonate, 4,5-dimethylvinylene carbonate, 4,5-diethylvinylene carbonate, and 4-methyl-5-ethylvinylene carbonate. At least one vinylene carbonate compound selected from the group, and / or 4-vinylethylene carbonate, 4-vinyl-4-methylethylene carbonate, 4-vinyl-4-ethylethylene carbonate, 4
-Vinyl-4-n-propyl ethylene carbonate, 4
-Vinyl-5-methylethylene carbonate, 4-vinyl-5-ethylethylene carbonate, 4-vinyl-5
At least one vinyl ethylene carbonate compound selected from the group consisting of -n-propyl ethylene carbonate, and 10.1 to 10% with respect to the total weight of the non-aqueous electrolyte solution.
The non-aqueous electrolyte solution according to claim 1, which is 15% by weight. 10. The cyclic amide compound represented by the formula (I), and / or the cyclic carbamate compound represented by the formula (II), and / or the cyclic hetero compound represented by the formula (III) is a non-aqueous system. 0.1 to the total weight of electrolyte
The non-aqueous electrolyte solution according to claim 1, which is 15% by weight. 11. The lithium salt is LiPF₆, Li
BF_FourInorganic acid lithium salt selected from, or LiCF₃S
O₃, LiN (CF₃SO₂)₂, LiN (C₂F _FiveS
O₂)₂, LiN (CF₃SO₂) (C_FourF₉SO₂), Li
PF₃(C₂F_Five)₃, LiB (CF₃COO)_FourA group of
1 to 10, which is a lithium salt of an organic acid selected from the group consisting of:
The non-aqueous electrolyte solution described. 12. A lithium secondary battery comprising the non-aqueous electrolyte solution according to claim 1 and a positive electrode and a negative electrode capable of inserting and extracting lithium. 13. The negative electrode, as a negative electrode material, has a d value of a lattice plane (002 plane) of 0.335 to 0.
34 nm carbon material, and / or oxide of one or more metal selected from the group consisting of Sn, Si and Al, and / or one or more metal selected from the group consisting of Sn, Si and Al, and lithium The lithium secondary battery according to claim 12, comprising the alloy of.