JP2007258102A - Nonaqueous electrolytic solution, and nonaqueous electrolytic solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution which has low temperature characteristics, and which is capable of providing a battery having superior storage characteristics and cycle characteristics with a small amount of gas generation and having high capacity, and to provide a nonaqueous electrolytic solution battery manufactured by using it. <P>SOLUTION: In the nonaqueous electrolytic solution containing an electrolyte and a nonaqueous solvent to dissolve it, the nonaqueous electrolytic solution contains cyclic carbonates having an unsaturated bond, and furthermore contains a compound expressed by formula (1) (in the formula (1), R<SB>1</SB>and R<SB>2</SB>are 1-12C alkyl groups which independently may have an ether bond in the structure, and also may be substituted by a fluorine atom). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

Non-aqueous electrolyte batteries such as lithium secondary batteries are being put to practical use in a wide range of applications from so-called consumer power sources such as mobile phones and laptop computers to in-vehicle power sources for automobiles and the like. However, the demand for higher performance of non-aqueous electrolyte batteries in recent years is increasing, and there is a demand for improvement in battery characteristics.
The electrolyte used for a non-aqueous electrolyte battery is usually composed mainly of an electrolyte and a non-aqueous solvent. The main components of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate and propylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone. It is used.

In addition, in order to improve battery characteristics such as load characteristics, cycle characteristics, storage characteristics, and low temperature characteristics of such nonaqueous electrolyte batteries, various studies have been made on nonaqueous solvents and electrolytes.
For example, when a mixture of asymmetric chain carbonate and a cyclic carbonate having a double bond is used as a non-aqueous solvent, the cyclic carbonate having a double bond preferentially reacts with the negative electrode to form a good film on the negative electrode surface. Thus, since formation of a non-conductive film on the negative electrode surface due to the asymmetric chain carbonate is suppressed, Patent Document 1 discloses that storage characteristics and cycle characteristics are improved.

Further, Patent Document 2 discloses that the safety during overcharge can be improved by using an electrolyte containing a dicarboxylic acid diester (excluding oxalic acid diester and succinic acid diester) or a derivative thereof. .
Japanese Patent Laid-Open No. 11-185806 JP 2002-367673 A

However, the demand for higher performance of batteries in recent years has been increasing, and it is required to achieve high capacity, high temperature storage characteristics, and cycle characteristics at a high level.
As a method for increasing the capacity of a non-aqueous electrolyte battery, it has been studied to pack as many active materials as possible in a limited battery volume. In general, the design is such that the volume other than the active material in the interior is reduced as much as possible. However, there is a problem that the voids inside the battery are reduced due to the increase in capacity, and even if a small amount of gas is generated due to the decomposition of the electrolyte, the internal pressure of the battery is significantly increased.

If a large amount of gas is generated, a safety valve may be activated in a battery that senses this when the internal pressure is abnormally increased due to an abnormality such as overcharge and activates the safety valve. Further, in a battery without a safety valve, the battery may expand due to the pressure of the generated gas, and the battery itself may become unusable.
Therefore, non-aqueous electrolyte secondary batteries are strongly required to suppress gas generation as well as high capacity, high temperature storage characteristics, and cycle characteristics.

However, the non-aqueous electrolyte secondary batteries using the electrolytes described in Patent Documents 1 and 2 have not yet been satisfactory in terms of achieving both cycle characteristics and suppression of gas generation.
Furthermore, when the electrolytic solution containing a cyclic carbonate having a double bond described in Patent Document 2 is used, a high-resistance film is formed on the negative electrode side. There was also the problem of a drop.

  Therefore, the object of the present invention is to increase the gas generation and decrease the charge / discharge characteristics at low temperatures when using non-aqueous electrolytes containing cyclic carbonates having unsaturated bonds such as vinylene carbonate. There is to solve.

As a result of various studies to achieve the above object, the present inventors have incorporated the compound having a specific structure into the electrolytic solution together with the cyclic carbonate having an unsaturated bond. The inventors have found that this can be solved, and have completed the present invention.
That is, the gist of the present invention is that, in a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent for dissolving the electrolyte, the non-aqueous electrolyte solution contains a cyclic carbonate having an unsaturated bond, and the following general formula (1) A non-aqueous electrolytic solution characterized by containing a compound represented by the formula:

(In the formula (1), R ₁ and R ₂ are each independently an alkyl having 1 to 12 carbon atoms which may have an ether bond in the structure and may be substituted with a fluorine atom. Group.)
Another gist of the present invention is a non-aqueous electrolyte battery including a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is the non-aqueous electrolyte solution described above. The non-aqueous electrolyte battery is characterized by the following.

  According to the present invention, it is possible to provide a nonaqueous electrolyte battery that is excellent in low temperature characteristics, has a small amount of gas generation, has a high capacity, and has excellent storage characteristics and cycle characteristics. High performance can be achieved.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.
<Non-aqueous electrolyte>
The non-aqueous electrolyte solution of the present invention contains an electrolyte and a non-aqueous solvent that dissolves the electrolyte, as is the case with conventional non-aqueous electrolyte solutions.
(Electrolytes)
As the electrolyte, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used. Specific examples include the following.

For example, inorganic lithium salts such as LiPF ₆ and LiBF ₄ ; LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide Lithium cyclic 1,3-perfluoropropane disulfonylimide, LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , Li
PF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ S
And fluorine-containing organic lithium salts such as O ₂ ) ₂ and lithium bis (oxalate) borate.

Of these, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ or LiN (C ₂ F ₅ SO ₂ ) ₂ are preferable from the viewpoint of improving battery performance, and in particular, LiPF ₆ or LiB.
F ₄ is preferred.
These lithium salts may be used alone or in combination of two or more.
A preferred example in the case of using two or more types in combination is the combined use of LiPF ₆ and LiBF ₄ , which has an effect of improving cycle characteristics. In this case, the proportion of LiBF _{4 in} the total of both is preferably 0.01% by weight or more, particularly preferably 0.1% by weight or more, preferably 20% by weight or less, particularly preferably 5% by weight or less. is there. If the lower limit is not reached, it may be difficult to obtain a desired effect. If the upper limit is exceeded, battery characteristics after high-temperature storage tend to deteriorate.

Another example is the combined use of an inorganic lithium salt and a fluorine-containing organic lithium salt. In this case, the proportion of the inorganic lithium salt in the total of both is 70% by weight or more and 99% by weight or less. It is desirable. Examples of the fluorine-containing organic lithium salt include LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane. It is preferably any of disulfonylimide. The combined use of both has the effect of suppressing deterioration due to high temperature storage.

When the non-aqueous solvent contains 55% by volume or more of γ-butyrolactone, the lithium salt is preferably LiBF ₄ or a combination of LiBF ₄ and another. In this case, LiBF ₄ preferably accounts for 40 mol% or more of the lithium salt. Particularly preferably, the proportion of LiBF _{4 in} the lithium salt is 40 mol% or more and 95 mol% or less, and the rest is Li
The combination is selected from the group consisting of PF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiN (C ₂ F ₅ SO ₂ ) ₂ .

The concentration of these electrolytes in the nonaqueous electrolytic solution is not particularly limited, but is usually 0.5 mol / liter or more, preferably 0.6 mol / liter or more, more preferably 0.7 mol / liter or more. . The upper limit is usually 3 mol / liter or less, preferably 2 mol / liter or less, more preferably 1.8 mol / liter or less, and still more preferably 1.5 mol / liter or less. If the concentration is too low, the electrical conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to an increase in viscosity, and the battery performance may decrease. .
(Non-aqueous solvent)
The non-aqueous solvent can also be appropriately selected from conventionally known solvents for non-aqueous electrolyte solutions. Examples thereof include cyclic carbonates having no unsaturated bond, chain carbonates, cyclic ethers, chain ethers, cyclic carboxylic acid esters, chain carboxylic acid esters, and phosphorus-containing organic solvents.

Examples of the cyclic carbonates having no unsaturated bond include alkylene carbonates having an alkylene group having 2 to 4 carbon atoms such as ethylene carbonate, propylene carbonate, and butylene carbonate. Among these, ethylene carbonate, propylene carbonate, and the like. Is preferable from the viewpoint of improving battery characteristics, and ethylene carbonate is particularly preferable.
As the chain carbonates, dialkyl carbonates are preferable, and the number of carbon atoms of the alkyl group constituting each is preferably 1 to 5, particularly preferably 1 to 4. Specifically, for example, symmetric chain alkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-n-propyl carbonate; asymmetric chain alkyls such as ethyl methyl carbonate, methyl-n-propyl carbonate, and ethyl-n-propyl carbonate Examples thereof include dialkyl carbonates such as carbonates. Among these, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable from the viewpoint of improving battery characteristics (particularly, high load discharge characteristics).

Examples of cyclic ethers include tetrahydrofuran and 2-methyltetrahydrofuran.
Examples of chain ethers include dimethoxyethane and dimethoxymethane.
Examples of cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone.

Examples of chain carboxylic acid esters include methyl acetate, methyl propionate, ethyl propionate, and methyl butyrate.
Examples of the phosphorus-containing organic solvent include trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, and the like.

These may be used alone or in combination of two or more, but it is preferable to use in combination of two or more. For example, it is preferable to use a high dielectric constant solvent such as alkylene carbonates or cyclic carboxylic acid esters in combination with a low viscosity solvent such as dialkyl carbonates or chain carboxylic acid esters.
One preferable combination of the non-aqueous solvents is a combination mainly composed of alkylene carbonates and dialkyl carbonates. Among them, the total of alkylene carbonates and dialkyl carbonates in the non-aqueous solvent is 80% by volume or more, preferably 85% by volume or more, more preferably 90% by volume or more, and the alkylene carbonates and dialkyl carbonates. The amount of alkylene carbonate with respect to the sum of the above is 5% or more, preferably 10% or more, more preferably 15% or more, usually 50% or less, preferably 35% or less, more preferably 30% or less, and still more preferably 25%. % Or less. Use of a combination of these non-aqueous solvents is preferable because the balance between cycle characteristics and high-temperature storage characteristics (particularly, remaining capacity and high-load discharge capacity after high-temperature storage) of a battery produced using the non-aqueous solvent is improved.

  Specific examples of preferable combinations of alkylene carbonates and dialkyl carbonates include ethylene carbonate and dimethyl carbonate, ethylene carbonate and diethyl carbonate, ethylene carbonate and ethyl methyl carbonate, ethylene carbonate and dimethyl carbonate and diethyl carbonate, ethylene carbonate and dimethyl carbonate, Examples include ethyl methyl carbonate, ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

A combination in which propylene carbonate is further added to a combination of these ethylene carbonate and dialkyl carbonates is also mentioned as a preferable combination.
In the case of containing propylene carbonate, the volume ratio of ethylene carbonate to propylene carbonate is preferably 99: 1 to 40:60, particularly preferably 95: 5 to 50:50. Furthermore, the amount of propylene carbonate in the whole non-aqueous solvent is 0.1% by volume or more, preferably 1% by volume or more, more preferably 2% by volume or more, and the upper limit is usually 20% by volume or less, preferably 8% by volume. % Or less, more preferably 5% by volume or less. When propylene carbonate is contained within this range, it is preferable because the low temperature characteristics are further excellent while maintaining the combination characteristics of ethylene carbonate and dialkyl carbonates.

  Among the combinations of ethylene carbonate and dialkyl carbonates, those in which the dialkyl carbonates are asymmetrical chain alkyl carbonates are more preferable, especially ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl. Carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferable because they contain a symmetrical chain alkyl carbonate and an asymmetric chain alkyl carbonate because the balance between cycle characteristics and large current discharge characteristics is good. . Among them, the asymmetric chain alkyl carbonate is preferably ethyl methyl carbonate, and the alkyl group of the alkyl carbonate preferably has 1 to 2 carbon atoms.

  Other examples of preferable non-aqueous solvents include one organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, γ-butyrolactone and γ-valerolactone, or two or more organic solvents selected from the group The mixed solvent becomes 60% by volume or more of the whole. The non-aqueous electrolyte using this mixed solvent is less likely to evaporate or leak when used at high temperatures. Among these, the total of ethylene carbonate and γ-butyrolactone in the nonaqueous solvent is 80% by volume or more, preferably 90% by volume or more, and the volume ratio of ethylene carbonate and γ-butyrolactone is 5:95 to 45%. : 55, or the total of ethylene carbonate and propylene carbonate in the non-aqueous solvent is 80% by volume or more, preferably 90% by volume or more, and the volume ratio of ethylene carbonate to propylene carbonate is 30:70 to Use of a material having a ratio of 60:40 generally improves the balance between cycle characteristics and large current discharge characteristics.

  It is also preferable to use a phosphorus-containing organic solvent as the non-aqueous solvent. When the phosphorus-containing organic solvent is contained in the non-aqueous solvent in an amount of usually 5% by volume or more, preferably 10% by volume or more and usually 80% by volume or less, the flammability of the electrolytic solution can be lowered. In particular, when a phosphorus-containing organic solvent is used in combination with a nonaqueous solvent selected from the group consisting of ethylene carbonate, propylene carbonate, γ-butyrolactone, γ-valerolactone, and dialkyl carbonate, cycle characteristics and large current discharge characteristics This is preferable because the balance is improved.

In the present specification, the capacity of the non-aqueous solvent is a measured value at 25 ° C., but a measured value at the melting point is used for a solid at 25 ° C. such as ethylene carbonate.
(Cyclic carbonates having an unsaturated bond)
Examples of cyclic carbonates having an unsaturated bond include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, fluorovinylene carbonate, trifluoromethyl vinylene carbonate, and the like. Vinylene carbonate compounds; vinyl ethylene carbonate, 4-methyl-4-vinylethylene carbonate, 4-ethyl-4-vinylethylene carbonate, 4-n-propyl-4-vinylethylene carbonate, 5-methyl-4-vinylethylene carbonate , 4,4-divinylethylene carbonate, vinylethylene carbonate such as 4,5-divinylethylene carbonate; 4,4-dimethyl-5-methyleneethylene car Sulfonates, such as methylene ethylene carbonate compounds such as 4,4-diethyl-5-methylene ethylene carbonate. Among these, vinylene carbonate, vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate or 4,5-divinyl ethylene carbonate is preferable from the viewpoint of improving cycle characteristics, and among them, vinylene carbonate or vinyl ethylene carbonate is more preferable. Vinylene carbonate is preferred. These may be used alone or in combination of two or more. In particular, it is preferable to use vinylene carbonate and vinyl ethylene carbonate in combination because cycle characteristics are further improved.

The proportion of the cyclic carbonate having an unsaturated bond in the non-aqueous electrolyte is usually 0.001% by weight or more, preferably 0.1% by weight or more, particularly preferably 0.3% by weight or more, and most preferably 0.8%. It is 5% by weight or more, usually 8% by weight or less, preferably 5% by weight or less, particularly preferably 3% by weight or less. If the content is small, the cycle characteristics may not be sufficiently improved at room temperature. On the other hand, if the content is too large, the internal pressure of the battery may increase due to gas generation during high temperature storage.
(Compound represented by the general formula (1))
The nonaqueous electrolytic solution according to the present invention contains the above-described electrolyte, a nonaqueous solvent, and a cyclic carbonate having an unsaturated bond, and further contains a compound represented by the following general formula (1).

(In the formula (1), R ₁ and R ₂ each independently have an ether bond in the structure and may be substituted with a fluorine atom, having 1 to 12 carbon atoms. Represents an alkyl group.)
In said general formula (1), as a C1-C12 alkyl group, a methyl group, an ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl is mentioned, for example. And linear, branched or cyclic alkyl groups such as a group, tert-butyl group, pentyl group, cyclopentyl group and cyclohexyl group. 1-6 are preferable and 1-4 are especially preferable. A chain alkyl group is preferred from the viewpoint of ease of synthesis and battery characteristics. Moreover, what is a linear alkyl group is especially preferable.

The alkyl group may contain an ether bond in its structure, and examples of the group having an ether bond in the structure of the alkyl group include a methoxymethyl group, a 2-methoxyethyl group, and 2- Examples include alkoxyalkyl groups such as ethoxyethyl group.
Furthermore, the alkyl group may be substituted with a fluorine atom. Examples of the group substituted with a fluorine atom include fluorinated alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, and a pentafluoroethyl group. Can be mentioned.

The molecular weight of the compound represented by the general formula (1) is usually 144 or more, and the upper limit is usually 1000 or less, preferably 500 or less, more preferably 300 or less. On the other hand, if the upper limit is exceeded, the viscosity tends to increase and the battery performance tends to decrease.
Specific examples of the compound represented by the general formula (1) include dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dicyclopentyl maleate, dicyclohexyl maleate, bis (trifluoromethyl) maleate, Bis (pentafluoroethyl) maleate, bis (2,2,2-trifluoroethyl) maleate, bis (methoxymethyl) maleate, bis (2-methoxyethyl) maleate, bis (2-ethoxyethylmaleate) ), Bis (3-methoxypropyl) maleate, bis [2- (2-
Methoxyethoxy) ethyl], bis [2- (2-ethoxyethoxy) ethyl maleate], dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate, bis fumarate ( Trifluoromethyl), bis (pentafluoroethyl) fumarate, bis (2,2,2-trifluoroethyl) fumarate, bis (methoxymethyl) fumarate, bis (2-methoxyethyl) fumarate, bis fumarate (2-ethoxyethyl), bis (3-methoxypropyl) fumarate, bis [2- (2-methoxyethoxy) ethyl fumarate], bis [2- (2-ethoxyethoxy) ethyl fumarate] and the like. .

Among these, dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dicyclopentyl maleate, dicyclohexyl maleate, bis (trifluoromethyl) maleate, bis (pentafluoroethyl) maleate, maleic acid Bis (2,2,2-trifluoroethyl), dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, dicyclopentyl fumarate, dicyclohexyl fumarate, bis (trifluoromethyl) fumarate, bis fumarate R ₁ and R ₂ such as (pentafluoroethyl), bis (2,2,2-trifluoroethyl) fumarate and the like are alkyl groups which may be substituted with fluorine atoms for ease of synthesis and battery It is preferable in terms of characteristics.

Also, dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dicyclopentyl maleate, dicyclohexyl maleate, dimethyl fumarate, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, dicyclopentyl fumarate, fumaric acid More preferably, R ₁ and R ₂ such as dicyclohexyl are alkyl groups.

The compound represented by the general formula (1) can be synthesized by a method known per se.
The compound represented by the general formula (1) may be used alone or in combination of two or more. The content of the compound represented by the general formula (1) in the non-aqueous electrolyte is usually 0.001% by weight or more, preferably 0.1% by weight or more, more preferably 0.2% by weight or more, particularly Preferably it is 0.25% by weight or more. If the concentration is lower than this, the effect of the present invention tends to be hardly exhibited. On the other hand, if the concentration is too high, the storage characteristics of the battery tend to deteriorate. Therefore, the upper limit is usually 4% by weight or less, preferably 3% by weight or less, more preferably 2% by weight or less, and particularly preferably 1% by weight or less. Most preferably, it is 0.4% by weight or less.

The reason why the non-aqueous electrolyte solution according to the present invention suppresses gas generation of the non-aqueous electrolyte secondary battery and also improves the charge / discharge characteristics at low temperature is not clear, and the present invention is limited to the following principle of operation. Although not done, it is presumed as follows.
First, cyclic carbonates having an unsaturated bond such as vinylene carbonate are reduced during initial charging, and a stable film is formed on the surface of the negative electrode to improve the storage characteristics and cycle characteristics of the battery. However, this film has a remarkable increase in resistance at a low temperature, and has a problem that charge / discharge characteristics deteriorate at a low temperature.

  On the other hand, by containing the compound represented by the general formula (1) in the electrolytic solution, an excessive reaction of the cyclic carbonate having an unsaturated bond is suppressed, and at the same time, an unsaturated bond is formed on the negative electrode surface. A composite film derived from a compound represented by the general formula (1) and a cyclic carbonate having a hydrogen atom is formed, and the composite film has excellent lithium ion permeability even at low temperatures. While maintaining, good cycle characteristics can be achieved even at low temperatures.

In addition, the cyclic carbonate having an unsaturated bond is likely to react with the positive electrode material in a charged state, and particularly under a high temperature atmosphere, the reaction with the positive electrode material proceeds, and the deterioration of the positive electrode active material is promoted or the amount of gas generated is reduced. increase. In contrast, the compound represented by the general formula (1) forms a film on the surface of the positive electrode, prevents contact between the cyclic carbonate having an unsaturated bond and the positive electrode, and can suppress an increase in the amount of gas generated. I think that the.
(Other compounds)
The non-aqueous electrolyte solution of the present invention may contain various other compounds such as a conventionally known overcharge inhibitor as an auxiliary agent as long as the effects of the present invention are not impaired.

By containing an overcharge preventing agent, rupture / ignition of the battery can be suppressed during overcharge or the like.
As an overcharge inhibitor, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran; 2-fluorobiphenyl, Partially fluorinated products of the above aromatic compounds such as o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene; 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, 3,5-difluoroanisole and the like And a fluorine-containing anisole compound.

  Of these, aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran are preferable. Two or more of these may be used in combination. When two or more types are used in combination, in particular, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, biphenyl, alkylbiphenyl, terphenyl, terphenyl partially hydrogenated product, cyclohexylbenzene, t-butylbenzene The balance between overcharge prevention characteristics and high-temperature storage characteristics is obtained by using a combination selected from oxygen-free aromatic compounds such as t-amylbenzene and oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran. From the viewpoint of

  The proportion of the overcharge inhibitor in the non-aqueous electrolyte is usually 0.1% by weight or more, preferably 0.2% by weight or more, particularly preferably 0.3% by weight or more, and most preferably 0.5% by weight or more. The upper limit is usually 5% by weight or less, preferably 3% by weight or less, and particularly preferably 2% by weight or less. When the concentration is lower than this lower limit, the effect of the overcharge inhibitor hardly appears. Conversely, if the concentration is too high, battery characteristics such as high-temperature storage characteristics tend to deteriorate.

  Other auxiliaries include carbonate compounds such as fluoroethylene carbonate, difluoroethylene carbonate, trifluoropropylene carbonate, erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, Carboxylic anhydrides such as maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 2, Spiro compounds such as 4,8,10-tetraoxaspiro [5.5] undecane and 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, 1, 3-propans Ton, 1,4-butane sultone, methyl methanesulfonate, ethyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethylsulfone, diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, etc. Sulfur compounds; nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide Hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane, and fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride. Two or more of these may be used in combination.

The ratio of these auxiliaries in the non-aqueous electrolyte is usually 0.01% by weight or more, preferably 0.1% by weight or more, particularly preferably 0.2% by weight or more, and the upper limit is usually 5% by weight. Hereinafter, it is preferably 3% by weight or less, particularly preferably 1% by weight or less. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved. When the concentration is lower than this lower limit, the effect of the auxiliary agent hardly appears. Conversely, if the concentration is too high, battery characteristics such as high-load discharge characteristics tend to deteriorate.

(Preparation of electrolyte)
The non-aqueous electrolyte solution according to the present invention includes, in a non-aqueous solvent, at least one compound selected from the group consisting of an electrolyte, a cyclic carbonate having an unsaturated bond, and a compound represented by the general formula (1), and as necessary. Accordingly, it can be prepared by dissolving other compounds. In preparing the non-aqueous electrolyte solution, each raw material is preferably dehydrated in advance in order to reduce the water content when the electrolyte solution is used. Usually, it is good to dehydrate to 50 ppm or less, preferably 30 ppm or less, particularly preferably 10 ppm or less. Moreover, you may implement dehydration, a deoxidation process, etc. after electrolyte solution preparation.
The non-aqueous electrolyte of the present invention is suitable for use as a secondary battery among non-aqueous electrolyte batteries, that is, as an electrolyte for a non-aqueous electrolyte secondary battery, for example, a lithium secondary battery. Hereinafter, a non-aqueous electrolyte secondary battery using the electrolyte of the present invention will be described.

<Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte battery including a negative electrode and a positive electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte, and the non-aqueous electrolyte is the above-described electrolyte. It is characterized by being.

(Battery configuration)
The non-aqueous electrolyte secondary battery according to the present invention is the same as the conventionally known non-aqueous electrolyte secondary battery except that it is produced using the electrolyte of the present invention, and a negative electrode capable of inserting and extracting lithium ions and A non-aqueous electrolyte battery including a positive electrode and a non-aqueous electrolyte, usually obtained by housing a positive electrode and a negative electrode in a case through a porous membrane impregnated with the non-aqueous electrolyte according to the present invention. . Therefore, the shape of the secondary battery according to the present invention is not particularly limited, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

(Negative electrode)
As the negative electrode active material, a carbonaceous material or metal compound capable of inserting and extracting lithium, lithium metal, lithium alloy, and the like can be used. These negative electrode active materials may be used alone or in combination of two or more. Among these, a carbonaceous material and a metal compound capable of occluding and releasing lithium are preferable.

Among the carbonaceous materials, graphite and graphite whose surface is coated with amorphous carbon as compared with graphite are particularly preferable.
Graphite preferably has a lattice plane (002 plane) d value (interlayer distance) of 0.335 to 0.338 nm, particularly 0.335 to 0.337 nm, as determined by X-ray diffraction using the Gakushin method. The crystallite size (Lc) determined by X-ray diffraction by the Gakushin method is usually 30 nm or more, preferably 50 nm or more, particularly preferably 100 nm or more. The ash content is usually 1% by weight or less, preferably 0.5% by weight or less, particularly preferably 0.1% by weight or less.

  The graphite surface coated with amorphous carbon is preferably graphite having a d-value of 0.335 to 0.338 nm on the lattice plane (002 plane) in X-ray diffraction as a core material. A carbonaceous material having a larger d-value on the lattice plane (002 plane) in X-ray diffraction than the core material is attached, and the d-value on the lattice plane (002 plane) in X-ray diffraction is greater than that of the core material and the core material. The ratio with respect to the carbonaceous material having a large is 99/1 to 80/20 by weight. When this is used, a negative electrode having a high capacity and hardly reacting with the electrolytic solution can be produced.

The particle size of the carbonaceous material is a median diameter measured by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, most preferably 7 μm or more, and usually 100 μm or less, preferably 50 μm or less. More preferably, it is 40 micrometers or less, Most preferably, it is 30 micrometers or less.
The specific surface area of the carbonaceous material by the BET method is usually 0.3 m ² / g or more, preferably 0.5
m ² / g or more, more preferably 0.7 m ² / g or more, and most preferably 0.8 m ² / g or more and usually 25.0 m ² / g or less, preferably 20.0 m ² / g, more Preferably it is 15.0 m < ² > / g or less, Most preferably, it is 10.0 m < ² > / g or less.

Further, the carbonaceous material is analyzed by Raman spectrum using argon ion laser light, the peak is the peak intensity of the peak P _A in the range of 1570~1620cm ^-1 I _A, in the range of 1300~1400cm ^-1 P If the peak intensity of the _B was I _B, R value represented by the ratio of I _B and _{I a (= I B / I} a) is what is preferably in the range of 0.01 to 0.7. Further, the half width of the peak in the range of 1570～1620Cm ^-1 is, 26cm ^-1 or less, are preferred in particular 25 cm ^-1 or less.

Examples of metal compounds capable of inserting and extracting lithium include compounds containing metals such as Ag, Zn, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, Cu, Ni, Sr, and Ba. These metals are used as simple substances, oxides, alloys with lithium, and the like. In the present invention, those containing an element selected from Si, Sn, Ge and Al are preferred, and oxides or lithium alloys of metals selected from Si, Sn and Al are more preferred. These may be in the form of powder or thin film, and may be crystalline or amorphous.

Lithium is a metal compound that can occlude and release lithium, or its oxides and alloys with lithium generally have higher capacity per unit weight than carbonaceous materials typified by graphite. It is suitable for a secondary battery.
The average grain system of the metal compound capable of inserting and extracting lithium or the oxide or an alloy thereof with lithium is usually 50 μm or less, preferably 20 μm or less, particularly preferably 10 μm or less, usually 0.1 μm or more, preferably 1 μm or more, Particularly preferably, it is 2 μm or more. When this upper limit is exceeded, the expansion of the electrode increases, and the cycle characteristics may deteriorate. Moreover, when less than this minimum, it becomes difficult to collect current and there is a possibility that the capacity is not sufficiently developed.

(Positive electrode)
Examples of the positive electrode active material include materials capable of inserting and extracting lithium, such as lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide. These compounds include Li _X CoO ₂ , Li _X NiO ₂ , Li _X MnO ₂ , Li _X Co _{1- y My} O ₂ , Li _X Ni _{1- y My} O ₂ , Li _X Mn _{1- y My} O ₂ or the like, where M is usually at least one selected from Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, V, Sr, Ti, 0.4 ≦ x ≦ 1.2, 0 ≦ y ≦ 0.6, or Li _X Mn _a Ni _b Co _c O ₂ (where 0.4 ≦ x ≦ 1.2, a + b + c = 1) Can be mentioned.

Especially represented by _{Li X Co 1-y M y} O 2, Li X Ni 1-y M y O 2, Li X Mn 1-y M y O 2 , etc., cobalt, nickel, and other part of manganese What is replaced with metal, or Li _X Mn _a Ni _b Co _c O ₂ (where 0.4 ≦ x ≦ 1.2, a + b + c = 1, | a−b | <0.1) It is preferable because the structure can be stabilized.
The positive electrode active materials may be used alone or in combination.

  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 adhering substances include 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 and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

  The amount of the surface adhering substance is by mass with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, still more preferably 10 ppm or more, and the upper limit is preferably 20% or less, more preferably 10%. % Or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolyte solution on the surface of the positive electrode active material, and can improve the battery life. However, when the amount of the adhering quantity is too small, the effect is not sufficiently exhibited. If the amount is too large, the resistance may increase in order to inhibit the entry and exit of lithium ions.

(electrode)
As the binder for binding the active material, any material can be used as long as it is a material that is stable with respect to the solvent and the electrolyte used in manufacturing the electrode. For example, fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, polyolefins such as polyethylene and polypropylene, polymers having unsaturated bonds such as styrene / butadiene rubber, isoprene rubber and butadiene rubber, and copolymers thereof, ethylene-acrylic Examples thereof include acrylic acid polymers such as acid copolymers and ethylene-methacrylic acid copolymers, and copolymers thereof.

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 carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.

Examples of the conductive material include a metal material such as copper or nickel, and a carbon material such as graphite or carbon black.
The electrode may be manufactured by a conventional method. For example, it can be formed by adding a binder, a thickener, a conductive material, a solvent or the like to a negative electrode or a positive electrode active material to form a slurry, applying the slurry to a current collector, drying it, and then pressing it.

In addition, a material obtained by adding a binder or a conductive material to an active material is roll-formed as it is to form a sheet electrode, a pellet electrode is formed by compression molding, and an electrode is formed on the current collector by a technique such as vapor deposition, sputtering, or plating. A thin film of material can also be formed.
When graphite is used as the negative electrode active material, the density of the negative electrode active material layer after drying and pressing is usually 1.45 g / cm ³ or more, preferably 1.55 g / cm ³ or more, particularly preferably 1.60 g. / Cm ³ or more.

Further, the density after drying and pressing of the positive electrode active material layer is usually 2.0 g / cm ³ or more, preferably 3.0 g / cm ³ or more.
Various types of current collectors can be used, but metals and alloys are usually used. Examples of the current collector for the negative electrode include copper, nickel, and stainless steel, and copper is preferred. Examples of the positive electrode current collector include metals such as aluminum, titanium, and tantalum, and alloys thereof, and aluminum or an alloy thereof is preferable.

(Separator, exterior body)
A porous film (separator) is interposed between the positive electrode and the negative electrode to prevent a short circuit. In this case, the electrolytic solution is used by impregnating the porous membrane. The material and shape of the porous film are not particularly limited as long as it is stable to the electrolytic solution and excellent in liquid retention, and a porous sheet or nonwoven fabric made of a polyolefin such as polyethylene or polypropylene is preferable.

The material of the battery casing used in the battery according to the present invention is also arbitrary, and nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, a laminate film, or the like is used.
The operating voltage of the non-aqueous electrolyte secondary battery of the present invention described above is usually in the range of 2V to 6V.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.
In addition, each evaluation method of the battery obtained by the following Example and the comparative example is shown below.
[Capacity evaluation]
A lithium secondary battery is charged to 4.2 V at a constant current corresponding to 0.2 C at 25 ° C. in a state of being sandwiched between glass plates in order to enhance adhesion between electrodes, and then a constant current of 0.2 C Was discharged to 3V. This is done for 3 cycles to stabilize the battery. In the 4th cycle, after charging to 4.2V with a constant current of 0.5C, charging is performed until the current value reaches 0.05C with a constant voltage of 4.2V. The initial discharge capacity was determined by discharging to 3 V at a constant current of 0.2C.
Here, 1C represents a current value for discharging the reference capacity of the battery in one hour, and 0.2C represents a current value of 1/5 thereof.

[Evaluation of low-temperature cycle characteristics]
After the capacity evaluation test was completed, the battery was charged at a constant current of 0.5 C to 4.2 V at 0 ° C., and then charged at a constant voltage of 4.2 V until the current value reached 0.05 C. A cycle test for discharging to 3 V at a constant current was performed. The discharge capacity (%) after 50 cycles when the discharge capacity before the cycle test was taken as 100 was determined.
[Evaluation of normal temperature cycle characteristics]
After the capacity evaluation test was completed, the battery was charged at a constant current of 0.5 C to 4.2 V at 25 ° C., and then charged at a constant voltage of 4.2 V until the current value reached 0.05 C. A constant current of 1 C A cycle test was conducted to discharge to 3V. The discharge capacity (%) after 300 cycles when the discharge capacity before the cycle test was taken as 100 was determined.

[Evaluation of continuous charge characteristics]
After the capacity evaluation test was completed, the volume was measured by immersing the battery in an ethanol bath. Then, constant current charging was performed at a constant current of 0.5 C at 60 ° C., and after reaching 4.25 V, constant voltage charging was performed. Switching was performed continuously for one week.

After the battery was cooled, it was immersed in an ethanol bath to measure the volume, and the amount of gas generated from the volume change before and after continuous charging was determined.
After measuring the amount of gas generated, discharge to 3 V at a constant current of 0.2 C at 25 ° C., measure the remaining capacity after the continuous charge test, and determine the ratio of the discharge capacity after the continuous charge test to the initial discharge capacity. Was the remaining capacity (%) after continuous charging.

Example 1
[Manufacture of negative electrode]
The d-value of the lattice plane (002 plane) in X-ray diffraction is 0.336 nm, the crystallite size (Lc) is 652 nm, the ash content is 0.07 wt%, and the median diameter by laser diffraction / scattering method is 12 μm.
m, specific surface area by BET method is 7.5 m ² / g, R value (= I _B / I _A ) determined from Raman spectrum analysis using argon ion laser light is 0.12, 1570-1620 cm ⁻¹ A natural graphite powder having a half width of 19.9 cm ⁻¹ of 94 parts by weight and 6 parts by weight of polyvinylidene fluoride were mixed, and N-methyl-2-pyrrolidone was added to form a slurry. This slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed to obtain a negative electrode active material layer having a density of 1.65 g / cm ³ to form a negative electrode.

[Production of positive electrode]
90 parts by weight of LiCoO ₂ , 4 parts by weight of carbon black and 6 parts by weight of polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd., trade name “KF-1000”) are mixed, and N-methyl-2-pyrrolidone is added to form a slurry. After uniformly applying and drying on both surfaces of a 15 μm thick aluminum foil, the positive electrode active material layer was pressed to a density of 3.0 g / cm ³ to obtain a positive electrode.

[Manufacture of electrolyte]
Under a dry argon atmosphere, 97.5 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate (volume ratio 2: 4: 4), 2 parts by weight of vinylene carbonate and 0.5 parts by weight of dimethyl maleate were mixed. Subsequently, fully dried LiPF ₆ was dissolved at a rate of 1.0 mol / liter to obtain an electrolytic solution.

[Manufacture of lithium secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, the positive electrode, the separator, and the negative electrode to produce a battery element. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then the electrolyte was poured into the bag and vacuum sealed. The sheet-like battery was manufactured and evaluated. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.

(Example 2)
A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that dimethyl fumarate was used instead of dimethyl maleate in the electrolytic solution of Example 1. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.
(Example 3)
97 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate, 2 parts by weight of vinylene carbonate, 0.5 parts by weight of vinyl ethylene carbonate and 0.5 parts by weight of dimethyl maleate were mixed and then thoroughly dried LiPF ₆ 1.
A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that an electrolytic solution prepared by dissolving at a rate of 0 mol / liter was used. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.

Example 4
A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that diethyl maleate was used in place of dimethyl maleate in the electrolytic solution of Example 1. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.
(Example 5)
A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that dibutyl maleate was used in place of dimethyl maleate in the electrolytic solution of Example 1. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.
(Example 6)
Mix 97.7 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate, 2 parts by weight of vinylene carbonate and 0.3 parts by weight of dimethyl maleate, and then add 1.0 mol / liter of fully dried LiPF ₆ A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that the electrolytic solution prepared by dissolving the mixture was used. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.

(Comparative Example 1)
The same as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried in a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate so as to have a ratio of 1.0 mol / liter was used. Then, a sheet-like lithium secondary battery was produced and evaluated. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.
(Comparative Example 2)
Mix 99.5 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate and 0.5 parts by weight of dimethyl maleate, and then dissolve LiPF ₆ sufficiently dried to a ratio of 1.0 mol / liter. A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that the electrolytic solution produced was used and vinylene carbonate was not used. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.

(Comparative Example 3)
98 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate and 2 parts by weight of vinylene carbonate were mixed, and then fully dried LiPF ₆
A sheet-like lithium secondary battery was prepared in the same manner as in Example 1 except that an electrolytic solution prepared by dissolving 1.0 mol / liter was used and dimethyl maleate was not used. And evaluated. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.
(Comparative Example 4)
A sheet-like lithium secondary battery was prepared and evaluated in the same manner as in Example 1 except that dimethyl oxalate was used in place of dimethyl maleate in the electrolytic solution of Example 1. The components of the electrolytic solution and the evaluation results are shown in Tables 1 and 2.

(Example 7)
In Example 1, a sheet-like lithium secondary battery was produced and evaluated in the same manner except that the negative electrode and the electrolyte obtained by the following method were used. The evaluation results are shown in Table 3.
[Manufacture of negative electrode]
Si powder (average particle size 3 μm) 73 parts by weight, Cu powder (average particle size 2 μm) 8 parts by weight, artificial graphite powder 12 parts by weight, polyvinylidene fluoride 7 parts by weight, N-methyl-2-pyrrolidone was mixed It was made into a slurry, and this slurry was uniformly applied to one side of a 12 μm thick copper foil, dried, and then pressed so that the density of the negative electrode active material layer was 1.0 g / cm ³ to obtain a negative electrode.

[Manufacture of electrolyte]
Under a dry argon atmosphere, 98.5 parts by weight of a mixture of ethylene carbonate, ethyl methyl carbonate and diethyl carbonate (volume ratio 2: 4: 4), 1 part by weight of vinylene carbonate and 0.5 parts by weight of dibutyl maleate were mixed. Then fully dried LiPF ₆
Was dissolved to a ratio of 1.0 mol / liter to obtain an electrolytic solution.
(Comparative Example 5)
99 parts by weight of a mixture of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate and 1 part by weight of vinylene carbonate were mixed, and then sufficiently dried LiPF ₆ was dissolved to a ratio of 1.0 mol / liter to perform electrolysis. A sheet-like lithium secondary battery was prepared in the same manner as in Example 7 except that the liquid was used and dibutyl maleate was not used, and continuous charging was evaluated. The evaluation results are shown in Table 3.

  As is apparent from Tables 1 to 3, it can be seen that the battery according to the present invention has a small amount of gas generation and is excellent in battery characteristics.

Claims (4)

In a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent that dissolves the electrolyte, the non-aqueous electrolyte solution contains a cyclic carbonate having an unsaturated bond, and further contains a compound represented by the following general formula (1). A non-aqueous electrolyte characterized by that.

(In the formula (1), R ₁ and R ₂ each independently have an ether bond in the structure and may be substituted with a fluorine atom, having 1 to 12 carbon atoms. Represents an alkyl group.)   The ratio of the compound represented by General formula (1) to a non-aqueous electrolyte solution is 0.001 to 4 weight%, The non-aqueous electrolyte solution of Claim 1 characterized by the above-mentioned.   3. The non-aqueous electrolyte solution according to claim 1, wherein the proportion of the cyclic carbonate having an unsaturated bond in the non-aqueous electrolyte solution is 0.001 to 8 wt%.   It is a non-aqueous electrolyte battery containing the negative electrode and positive electrode which can occlude / release lithium ion, and a non-aqueous electrolyte solution, Comprising: This non-aqueous electrolyte solution is a non-aqueous electrolyte solution as described in any one of Claims 1-3. A non-aqueous electrolyte battery characterized by the above.