JP2010232173A - Nonaqueous electrolytic solution and nonaqueous electrolytic solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution capable of providing a battery high in capacity and superior in storage characteristics, and to provide a nonaqueous electrolytic solution battery. <P>SOLUTION: One or more compounds expressed by general formula (1) are contained in a nonaqueous electrolytic solution. Here, in the general formula (1), R<SB>1</SB>to R<SB>4</SB>are each independently a 1-12C alkyl group, a 2-12C alkenyl group, a 6-12C allyl group, or a 7-12C aralkyl group, which may be substituted by fluorine atom. X is a 1-12C bivalent coupling group which may be substituted by the fluorine atom. <P>COPYRIGHT: (C)2011,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 nonaqueous 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 order to improve battery characteristics such as load characteristics, cycle characteristics, and storage characteristics of such non-aqueous electrolyte batteries, various studies have been made on non-aqueous solvents and electrolytes.
For example, in order to improve cycle characteristics, it has been proposed to add an amine and a diamine compound to the nonaqueous electrolytic solution.

JP-A-8-236155

However, the demand for higher performance of batteries in recent years is 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, it has been studied to pack as many active materials as possible in a limited battery volume. The active material layer of the electrode can be pressurized to increase the density, or other than the active material inside the battery. Designs that occupy as little volume as possible are common. However, pressurizing the active material layer of the electrode to increase the density or reducing the amount of the electrolyte makes it impossible to use the active material uniformly, and some lithium is precipitated due to a non-uniform reaction, Deterioration of the active material is promoted, and a problem that sufficient characteristics cannot be obtained easily occurs. In particular, when the battery is stored at a high temperature, the deterioration of the battery becomes large, and a non-aqueous electrolyte battery with little characteristic deterioration even when stored at a high temperature is demanded.

  The non-aqueous electrolyte secondary battery using the electrolyte described in Patent Document 1 has not yet been satisfactory in terms of high-temperature storage characteristics.

As a result of various studies to achieve the above object, the present inventors have found that the above problems can be solved by using an electrolytic solution containing a specific compound, and have completed the present invention. .
That is, the gist of the present invention is as follows.
(1) In a non-aqueous electrolyte solution containing an electrolyte and a non-aqueous solvent that dissolves the electrolyte, the non-aqueous electrolyte solution contains one or more compounds represented by the following general formula (1). A non-aqueous electrolyte solution.

(In General Formula (1), R _{1 to} R ₄ are each independently an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and 6 carbon atoms that may be substituted with a fluorine atom. A -12 aryl group or a C7-12 aralkyl group, X represents a C1-C12 divalent linking group optionally substituted with a fluorine atom.)
(2) It contains at least one compound selected from the group consisting of a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate and a difluorophosphate. The nonaqueous electrolytic solution according to (1) above, which is characterized.
(3) The above (1) or (1), wherein the cyclic carbonate compound having a carbon-carbon unsaturated bond is contained in the nonaqueous electrolytic solution at a ratio of 0.01% by mass to 8% by mass. Non-aqueous electrolyte solution as described in 2).
(4) A non-aqueous electrolyte battery including a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is any one of the above (1) to (3) A non-aqueous electrolyte battery characterized by being the non-aqueous electrolyte solution described.

  According to the present invention, a non-aqueous electrolyte battery having a high capacity and excellent storage characteristics can be provided, and the non-aqueous electrolyte battery can be reduced in size and performance.

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 , Li ₂ B ₁₂ F ₁₂ ; LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2 - Pa - tetrafluoroethane disulfonylimide, lithium cyclic _{1,3-perfluoropropanedisulfonylimide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiPF 4 ( _{CF 3) 2, LiPF 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 SO 2) fluorine-containing organic lithium salt and lithium bis _2, etc. (oxalato) borate, lithium difluoro (oxalato) borate and the like ani It is.

Among 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 LiPF ₆ or LiBF ₄ is particularly preferable. preferable.
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 content ratio of LiBF _{4 in} the total of both is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more as a lower limit. The upper limit is preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 3% by mass or less. If the lower limit is not reached, it may be difficult to obtain a desired effect. If the upper limit is exceeded, battery characteristics such as high load discharge characteristics may be deteriorated.

Another example is the combined use of an inorganic lithium salt and a fluorine-containing organic lithium salt. In this case, the content of the inorganic lithium salt in the total of both is 70% by mass or more and 99% by mass or less. It is desirable to be. The inorganic lithium salt is preferably LiPF ₆ . 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.

  The concentration of these electrolytes in the non-aqueous electrolyte solution is not particularly limited in order to exhibit the effects of the present invention, but is usually 0.5 mol / liter or more, preferably 0.8 mol / liter or more, more The amount is preferably 1.0 mol / liter or more, more preferably 1.1 mol / liter or more, and particularly preferably 1.2 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 1.6 mol / liter or less. If the concentration is too low, the electrical conductivity of the electrolyte solution 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. For example, cyclic carbonates having no carbon-carbon unsaturated bond or fluorine atom, chain carbonates, cyclic ethers, chain ethers, cyclic carboxylic acid esters, chain carboxylic acid esters, sulfur-containing organic solvents And phosphorus-containing organic solvents.

  Examples of the cyclic carbonates having no carbon-carbon unsaturated bond or fluorine atom include alkylene carbonates having an alkylene group having 2 to 4 carbon atoms such as ethylene carbonate, propylene carbonate, butylene carbonate, among these. , Ethylene carbonate and propylene carbonate are 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. Further, a part of hydrogen of the alkyl group may be substituted with fluorine.
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.

Examples of the cyclic ethers include tetrahydrofuran, 2-methyltetrahydrofuran and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine.
Examples of chain ethers include dimethoxyethane, diethoxyethane, and the like, and bis (trifluoroethoxy) ethane, ethoxytrifluoroethoxyethane, methoxytrifluoroethoxyethane, 1,1,1,2,2,3,4,5. , 5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-ethoxy-4-tri Fluoromethyl-pentane, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-propoxy-4-trifluoromethyl-pentane, 1,1,2,2-tetrafluoro Some hydrogen of these compounds such as ethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl-2,2,3,3-tetrafluoropropyl ether Compounds substituted with fluorine, and the like.

Examples of the cyclic carboxylic acid esters include γ-butyrolactone, γ-valerolactone, and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine.
Examples of chain carboxylates include methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, propion Examples include isopropyl acid, methyl butyrate, ethyl butyrate, propyl butyrate, methyl valerate, ethyl valerate, etc., and compounds in which part of hydrogen of these compounds such as propyl trifluoroacetate and butyl trifluoroacetate is substituted with fluorine. Propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate and methyl valerate are more preferred.

Examples of the sulfur-containing organic solvent include sulfolane, 2-methylsulfolane, 3-methylsulfolane, diethylsulfone and the like, and compounds obtained by substituting a part of hydrogen of these compounds with fluorine.
Examples of phosphorus-containing organic solvents include trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, etc., and compounds in which part of hydrogen in these compounds is substituted with fluorine Is mentioned.
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 ethylene carbonate and dialkyl carbonate. Among them, the total of ethylene carbonate and dialkyl carbonate in the nonaqueous solvent is 70% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more, and relative to the total of ethylene carbonate and dialkyl carbonate. The proportion of ethylene carbonate is 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, usually 50% by volume or less, preferably 35% by volume or less, more preferably 30% by volume or less, and still more preferably Is 25% by volume or less. Use of a combination of these non-aqueous solvents is preferable because the balance between the cycle characteristics and high-temperature storage characteristics (particularly, the 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 preferred combinations of ethylene carbonate and dialkyl carbonate 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 and ethyl methyl. Examples thereof include 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 lower limit of the proportion of propylene carbonate in the entire non-aqueous solvent is usually 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 it is 8 volume% or less, More preferably, it is 5 volume% or less. It is preferable to contain propylene carbonate in this concentration range because the low temperature characteristics are further excellent while maintaining the characteristics of the combination of ethylene carbonate and dialkyl carbonate.

  Among the combinations of ethylene carbonate and dialkyl carbonate, those containing asymmetrical chain alkyl carbonates as dialkyl carbonate are more preferred, especially ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, ethylene carbonate, diethyl carbonate and ethyl methyl carbonate. Those containing ethylene carbonate, symmetric chain alkyl carbonates, and asymmetric chain alkyl carbonates such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferred because of a good balance between cycle characteristics and large current discharge characteristics. 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.

  When diethyl carbonate is contained in the non-aqueous solvent, the lower limit of the proportion of diethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume. More preferably, it is 30% by volume or more, and the upper limit is usually 90% by volume or less, preferably 80% by volume or less, more preferably 75% by volume or less, and further preferably 70% by volume or less. When contained, gas generation during high-temperature storage is suppressed, which is preferable.

  In the case where dimethyl carbonate is contained in the non-aqueous solvent, the lower limit of the proportion of dimethyl carbonate in the total non-aqueous solvent is usually 10% by volume or more, preferably 20% by volume or more, more preferably 25% by volume. Or more, more preferably 30% by volume or more, and the upper limit is usually 90% by volume or less, preferably 80% by volume or less, more preferably 75% by volume or less, and further preferably 70% by volume or less. This is preferable because the load characteristics of the battery are improved.

In addition, in the combination mainly composed of the alkylene carbonates and dialkyl carbonates, other solvents may be mixed.
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 them, the total of ethylene carbonate and γ-butyrolactone in the nonaqueous solvent is 70% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more, and ethylene carbonate and γ-butyrolactone. The volume ratio is 5:95 to 45:55, or the total of ethylene carbonate and propylene carbonate in the non-aqueous solvent is 70% by volume or more, preferably 80% by volume or more, more preferably 90% by volume or more. In addition, if a volume ratio of ethylene carbonate to propylene carbonate of 30:70 to 60:40 is used, the balance between cycle characteristics and high temperature storage characteristics is generally 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.
(Compound represented by the general formula (1))
The nonaqueous electrolytic solution according to the present invention contains the above-described electrolyte and a nonaqueous solvent, and further contains a compound represented by the following general formula (1).

(In General Formula (1), R _{1 to} R ₄ are each independently an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and 6 carbon atoms that may be substituted with a fluorine atom. An -12 aryl group or an aralkyl group having 7 to 12 carbon atoms, X represents a divalent linking group having 1 to 12 carbon atoms.)

  Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, pentyl group, A cyclopentyl group, a cyclohexyl group, etc. are mentioned, Preferably it is a C1-C6, Especially preferably, a C1-C4 linear or cyclic alkyl group is mentioned, However, It is preferable that it is a linear alkyl group.

As a C2-C12 alkenyl group, a vinyl group, a propenyl group, etc. are mentioned, Preferably it is C2-C8, Most preferably, a C2-C4 thing is mentioned.
Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, and a xylyl group, and among them, a phenyl group is preferable.
Examples of the aralkyl group having 7 to 12 carbon atoms include a benzyl group and a phenethyl group, and among them, a benzyl group is preferable.

The alkyl group, alkenyl group, aryl group and aralkyl group may be substituted with a fluorine atom, and a group substituted with a fluorine atom is preferred.
Examples of the fluorine-substituted group include fluorinated alkyl groups such as trifluoromethyl group, trifluoroethyl group and pentafluoroethyl group, and fluorinated alkenyl groups such as 2-fluorovinyl group and 3-fluoro-2-propenyl group. Fluorinated aryl groups such as 2-fluorophenyl group, 3-fluorophenyl group and 4-fluorophenyl group, and fluorinated aralkyl groups such as 2-fluorobenzyl group, 3-fluorobenzyl group and 4-fluorobenzyl group. It is done. Of these, fluorinated alkyl groups having 1 to 3 carbon atoms such as a trifluoromethyl group, a trifluoroethyl group, and a pentafluoroethyl group are preferable.
As a C1-C12 bivalent coupling group, the following are mentioned, for example.

These divalent linking groups having 1 to 12 carbon atoms may be substituted with a fluorine atom. A preferable linking group includes a saturated or unsaturated hydrocarbon group which may be substituted with a fluorine atom, and a saturated hydrocarbon group is particularly preferable. The number of carbon atoms of the linking group is 1-8 preferably, most preferred linking group, - _(CH 2) n- _(where, n is 1 to 4) is.
The molecular weight of the compound represented by the general formula (1) is usually 214 or more, usually 2000 or less, preferably 1000 or less, more preferably 500 or less.
Specific examples of the compound represented by the general formula (1) include the following compounds.

Among them, A1, A2, A3, A6, A7, A8, A9, A10, A11, A12 are preferable, A6, A7, A8, A9, A10, A11, A12 are more preferable, A6, A7, A8, A9, A10. Is more preferable, and A8, A9, and A10 are particularly preferable.
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 nonaqueous electrolytic solution is usually 0.001% by mass or more, preferably 0.1% by mass or more, and more preferably 0.2% by mass or more. In particular, 0.3 mass% or more is preferable. If the concentration is lower than this, the effect of the present invention may 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 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass. Hereinafter, it is particularly preferably 0.8% by mass or less.

When the non-aqueous electrolyte solution according to the present invention is used, the reason why the non-aqueous electrolyte battery is excellent in high-temperature storage characteristics is not clear, and the present invention is not limited to the following operation principle. It is guessed as follows.
First, the compound represented by the general formula (1) has a nitrogen atom and an oxygen atom, is adsorbed on the surface of the positive electrode through these atoms, and prevents contact between the positive electrode having high activity and the electrolyte solution, It seems that the side reaction between the positive electrode and the electrolyte can be suppressed to suppress the deterioration of the positive electrode and to suppress the gas generation.

On the other hand, in the compound such as diamine described in Patent Document 1, because the oxidation potential of the compound is too low, the deterioration of the battery characteristics after high-temperature storage becomes remarkable, and furthermore, the adsorption ability to the positive electrode surface is low, There is almost no gas suppression effect.
(Other compounds)
The nonaqueous electrolytic solution according to the present invention is a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate, and a difluorophosphate within a range not impairing the effects of the present invention. Various other compounds such as at least one compound selected from the group consisting of and a conventionally known overcharge inhibitor may be contained as an auxiliary agent.
At least one selected from the group consisting of a compound represented by the general formula (1), a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate, and a difluorophosphate. It is preferable to use together with the compound because the battery characteristics after high-temperature storage are improved.

(Cyclic carbonate compound having a carbon-carbon unsaturated bond)
Examples of the cyclic carbonate compound having a carbon-carbon unsaturated bond include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl. Vinylene carbonate compounds such as vinylene carbonate; vinyl ethylene carbonate, 4-methyl-4-vinylethylene carbonate, 4-ethyl-4-vinylethylene carbonate, 4-n-propyl-4-vinylethylene carbonate, 5-methyl-4- Vinyl ethylene carbonate compounds such as vinyl ethylene carbonate, 4,4-divinyl ethylene carbonate, 4,5-divinyl ethylene carbonate; 4,4-dimethyl-5- Chi Ren ethylene carbonate, 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 cycle characteristics and capacity maintenance characteristics improvement after high-temperature storage. Among them, vinylene carbonate or Vinyl ethylene carbonate is more preferable, and vinylene carbonate is particularly preferable. These may be used alone or in combination of two or more.

When using 2 or more types together, it is preferable to use together vinylene carbonate and vinyl ethylene carbonate.
When the non-aqueous electrolyte contains a cyclic carbonate compound having a carbon-carbon unsaturated bond, the proportion in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly preferably. Is 0.3% by mass or more, and most preferably 0.5% by mass or more. When there are too few cyclic carbonate compounds which have a carbon-carbon unsaturated bond, the effect of improving the cycling characteristics of a battery and the capacity maintenance characteristics after high temperature storage may not be fully exhibited. However, if the content of the cyclic carbonate compound having a carbon-carbon unsaturated bond is too large, the amount of gas generated may increase during high-temperature storage, so the upper limit is usually 8% by mass or less, preferably 4 It is at most 3% by mass, particularly preferably at most 3% by mass.

(Cyclic carbonate compound having a fluorine atom)
Examples of the cyclic carbonate compound having a fluorine atom include fluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,4,5-trifluoroethylene carbonate, 4,4,5,5. -Tetrafluoroethylene carbonate, 4-fluoro-5-methylethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4,4,5-trifluoro-5-methyl Examples include ethylene carbonate, trifluoromethyl ethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, and the like. Of these, fluoroethylene carbonate, 4,5-difluoroethylene carbonate, and 4-fluoro-5-methylethylene carbonate are preferred from the viewpoint of improving cycle characteristics and capacity maintenance characteristics after high-temperature storage.

These may be used alone or in combination of two or more.
Further, it may be used in combination with a cyclic carbonate compound having a carbon-carbon unsaturated bond, and it is preferably used in combination with vinylene carbonate or vinyl ethylene carbonate from the viewpoint of improving cycle characteristics and capacity maintenance characteristics after high temperature storage. .
When the non-aqueous electrolyte contains a cyclic carbonate compound having a fluorine atom, the proportion in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly preferably 0.3%. % By mass or more, most preferably 0.5% by mass or more. When there are too few cyclic carbonate compounds which have a fluorine atom, the effect of improving the cycling characteristics of a battery and the capacity maintenance characteristic after high temperature storage may not fully be exhibited. However, if the content of the cyclic carbonate compound having a fluorine atom is too large, the amount of gas generated may increase during high-temperature storage, so the upper limit is usually 30% by mass or less, preferably 20% by mass or less, More preferably, it is 10 mass% or less, More preferably, it is 5 mass% or less, Most preferably, it is 3 mass% or less.

(Monofluorophosphate and difluorophosphate)
The counter cation of monofluorophosphate and difluorophosphate is not particularly limited, and examples thereof include lithium, sodium, potassium, magnesium, calcium, and lithium is preferable.
Specific examples of monofluorophosphate and difluorophosphate include lithium monofluorophosphate, sodium monofluorophosphate, potassium monofluorophosphate, lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. And lithium monofluorophosphate and lithium difluorophosphate are preferable, and lithium difluorophosphate is more preferable.

These may be used alone or in combination of two or more.
In addition, it may be used in combination with a cyclic carbonate compound having a carbon-carbon unsaturated bond or a cyclic carbonate compound having a fluorine atom. From the viewpoint of improving cycle characteristics and capacity retention characteristics after high-temperature storage, vinylene carbonate and vinyl are used. It is preferable to use in combination with ethylene carbonate and fluoroethylene carbonate.

  When the non-aqueous electrolyte contains a monofluorophosphate and / or difluorophosphate, the proportion in the non-aqueous electrolyte is usually 0.001% by mass or more, preferably 0.01% by mass or more, particularly Preferably it is 0.1 mass% or more, Most preferably, it is 0.2 mass% or more. If the content is too small, the effect of improving the cycle characteristics of the battery and the capacity maintenance characteristics after high-temperature storage may not be sufficiently exhibited. The upper limit is usually 5% by mass or less, preferably 3% by mass or less, and particularly preferably 2% by mass or less.

  As the overcharge inhibitor, alkylbiphenyl such as biphenyl, 2-methylbiphenyl, 2-ethylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane , Trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, methylphenyl Carbonate, ethylphenyl carbonate, diphenyl carbonate, triphenyl phosphate, tris (2-tert-butylphenyl) phosphate, tris (3-tert-butylphenyl) phosphate, tris (4- -Butylphenyl) phosphate, tris (2-t-amylphenyl) phosphate, tris (3-t-amylphenyl) phosphate, tris (4-t-amylphenyl) phosphate, tris (2-cyclohexylphenyl) phosphate, tris ( Aromatic compounds such as 3-cyclohexylphenyl) phosphate and tris (4-cyclohexylphenyl) phosphate; 2-fluorobiphenyl, 3-fluorobiphenyl, 4-fluorobiphenyl, 4,4′-difluorobiphenyl, o-cyclohexylfluorobenzene, Partially fluorinated products of the above aromatic compounds such as p-cyclohexylfluorobenzene; fluorine-containing anisols such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroanisole, and 3,5-difluoroanisole Le compounds.

  Among these, biphenyl, alkylbiphenyl such as 2-methylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexylbenzene, cis-1-propyl-4-phenylcyclohexane, trans-1-propyl-4 -Phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene, t-amylbenzene, diphenyl ether, dibenzofuran, methylphenyl carbonate, diphenyl carbonate, triphenyl phosphate , Aromatic compounds such as tris (4-t-butylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate; 2-fluorobiphenyl, 3-fluorobiphenyl, 4- Partially fluorinated products of the above-mentioned aromatic compounds such as fluorobiphenyl, 4,4′-difluorobiphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene, etc. are preferable. Partially hydrogenated terphenyl, cyclopentylbenzene, cyclohexylbenzene, cis -1-propyl-4-phenylcyclohexane, trans-1-propyl-4-phenylcyclohexane, cis-1-butyl-4-phenylcyclohexane, trans-1-butyl-4-phenylcyclohexane, t-butylbenzene, t- Amylbenzene, methylphenyl carbonate, diphenyl carbonate, triphenyl phosphate, tris (4-tert-butylphenyl) phosphate, tris (4-cyclohexylphenyl) phosphate, o-cyclohexyl Fluorobenzene, more preferably p- cyclohexyl fluorobenzene, partially hydrogenated member and cyclohexylbenzene terphenyl is particularly preferred.

  Two or more of these may be used in combination. When two or more types are used in combination, in particular, a partially hydrogenated terphenyl, a combination of cyclohexylbenzene and t-butylbenzene or t-amylbenzene, or a partially hydrogenated biphenyl, alkylbiphenyl, terphenyl or terphenyl. It is overcharged to use together those selected from oxygen-free aromatic compounds such as cyclohexylbenzene, t-butylbenzene, t-amylbenzene and those selected from oxygen-containing aromatic compounds such as diphenyl ether and dibenzofuran. This is preferable from the viewpoint of the balance between prevention characteristics and high-temperature storage characteristics.

  The content ratio of these overcharge inhibitors in the non-aqueous electrolyte is usually 0.1% by mass or more, preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more, and most preferably 0.5% by mass. The upper limit is usually 5% by mass or less, preferably 3% by mass or less, and particularly preferably 2% by mass or less. If the concentration is lower than this lower limit, the desired effect of the overcharge inhibitor may hardly be exhibited. 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 erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate, methoxyethyl-ethyl carbonate, ethoxyethyl-methyl carbonate, ethoxyethyl-ethyl carbonate; succinic anhydride Carboxylic acids such as glutaric anhydride, maleic anhydride, itaconic anhydride, citraconic anhydride, glutaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride Anhydride: dimethyl succinate, diethyl succinate, diallyl succinate, dimethyl maleate, diethyl maleate, diallyl maleate, dipropyl maleate, dibutyl maleate, bis maleate (trifluoro Dicarboxylic acid diester compounds such as bis (pentafluoroethyl) maleate, bis (2,2,2-trifluoroethyl) maleate; 2,4,8,10-tetraoxaspiro [5.5] undecane Spiro compounds such as 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, propylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, methyl methanesulfonate, ethyl methanesulfonate, methyl-methoxymethanesulfonate, methyl-2-methoxyethanesulfonate, busulfan, diethylene glycol dimethanesulfonate, 1,2-ethanediol bis ( 2,2,2-trifluoroethane Sulfonate), 1,4-butanediol bis (2,2,2-trifluoroethanesulfonate), sulfolane, 3-sulfolene, 2-sulfolene, dimethylsulfone, diethylsulfone, divinylsulfone, diphenylsulfone, N, N-dimethyl Sulfur-containing compounds such as methanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2- Nitrogen-containing compounds such as imidazolidinone and N-methylsuccinimide; charcoal such as heptane, octane, nonane, decane, cycloheptane, methylcyclohexane, ethylcyclohexane, propylcyclohexane, n-butylcyclohexane, t-butylcyclohexane, dicyclohexyl Hydrogen fluoride compounds; Fluorinated benzenes such as fluorobenzene, difluorobenzene and hexafluorobenzene; Nitrile compounds such as acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile; methyldimethylphosphinate, Ethyldimethylphosphinate, ethyldiethylphosphinate, trimethylphosphonoformate, triethylphosphonoformate, trimethylphosphonoacetate, triethylphosphonoacetate, trimethyl-3-phosphonopropionate, triethyl-3-phosphonopropioate Examples thereof include phosphorus-containing compounds such as nates. Among these, ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, 1,4-butene sultone, busulfan, 1,4 in terms of improving battery characteristics after high-temperature storage -Sulfur-containing compounds such as butanediol bis (2,2,2-trifluoroethanesulfonate); nitrile compounds such as acetonitrile, propionitrile, butyronitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, and pimelonitrile are preferable.

Two or more of these may be used in combination.
The content ratio of these auxiliaries in the non-aqueous electrolyte solution is not particularly limited in order to express the effect of the present invention, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly The upper limit is usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 1% by mass or less. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved. If the concentration is lower than this lower limit, the effect of the auxiliary agent may be hardly exhibited. On the other hand, if the concentration is too high, battery characteristics such as high load discharge characteristics may deteriorate.

(Preparation of electrolyte)
The non-aqueous electrolyte solution according to the present invention can be prepared by dissolving an electrolyte and, if necessary, other compounds in a non-aqueous solvent. 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 solution, usually obtained by housing the positive electrode and the negative electrode in a case through a porous membrane impregnated with the non-aqueous electrolyte solution 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)
The negative electrode active material is not particularly limited as long as it can occlude and release lithium ions. Carbonaceous materials and metal compounds capable of inserting and extracting lithium, lithium metal, lithium alloys, 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 mass or less, preferably 0.5% by mass or less, and particularly preferably 0.1% by mass 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 content ratio with a large carbonaceous material is 99/1 to 80/20 by weight ratio. 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, usually 25.0 m ² / g or less, preferably 20.0 m ² / g, more preferably 15.0 m ² / g or less, and most preferably 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 particle size of the metal compound capable of occluding and releasing lithium or the oxide or an alloy thereof with lithium is not particularly limited to express the effect of the present invention, but is usually 50 μm or less, preferably 20 μm or less, Particularly preferably, it is 10 μm or less, usually 0.1 μm or more, preferably 1 μm or more, particularly preferably 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)
The positive electrode active material is not particularly limited as long as it can occlude and release lithium ions. A substance containing lithium and at least one transition metal is preferable, and examples thereof include a lithium transition metal composite oxide and a lithium-containing transition metal phosphate compound.
The transition metal of the lithium transition metal composite oxide is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like, and specific examples include lithium / cobalt composite oxide such as LiCoO ₂ or LiNiO ₂ . Lithium / nickel composite oxide, LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO _{3 and} other lithium / manganese composite oxides, Al, Ti , V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, and those substituted with other metals such as Si. Specific examples of the substituted ones include, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O _4, etc. Is mentioned.

As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable, and specific examples include, for example, LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ). ₃ , iron phosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn , Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

These 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 substance constituting the main cathode active material is attached to the surface of the cathode 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 not particularly limited in order to exhibit the effects of the present invention, but is preferably 0.1 ppm or more, more preferably 1 ppm or more as a lower limit in terms of mass with respect to the positive electrode active material. The upper limit is preferably 10 ppm or more, preferably 20% or less, more preferably 10% or less, and still 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 electrolytic solution used during electrode production. 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, more preferably 1.60 g. / Cm ³ or more, particularly preferably 1.65 g / cm ³ or more.

The density of the positive electrode active material layer after drying and pressing is usually 2.0 g / cm ³ or more, preferably 2.5 g / cm ³ or more, 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]
The non-aqueous electrolyte 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 improve the adhesion between the electrodes, and then 0.2 C The battery was discharged to 3 V at a constant current of. 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 high-temperature storage characteristics]
After the capacity evaluation test was completed, the battery was immersed in an ethanol bath and the volume was measured. Then, the battery was charged to 4.2 V at a constant current of 0.5 C at 25 ° C., and the current value was set to 0.2 at a constant voltage of 4.2 V. The battery was charged until it reached 05C. Thereafter, the battery stored at 85 ° C. for 1 day was sufficiently cooled and then immersed in an ethanol bath to measure the volume, and the amount of gas generated from the volume change before and after storage was determined.

Next, it was discharged to 3 V at a constant current of 0.2 C at 25 ° C., the remaining capacity after the high-temperature storage test was measured, and the ratio of the discharge capacity after the storage test to the initial discharge capacity was obtained. The remaining capacity (%) was used.
Next, after charging to 4.2 V at a constant current of 0.5 C at 25 ° C., charging is performed until the current value reaches 0.05 C at a constant voltage of 4.2 V, and to 3 V at a constant current of 0.2 C. After discharging, the 0.2C discharge capacity after the high temperature storage test was measured, the ratio of the 0.2C discharge capacity after the storage test to the initial discharge capacity was determined, and this was defined as the recovery capacity (%) after the high temperature storage.

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% by mass, the median diameter by laser diffraction / scattering method is 12 μm, and the ratio by BET method The half-value width of a peak whose surface area is 7.5 m ² / g and R value (= I _B / I _A ) determined from Raman spectrum analysis using argon ion laser light is 0.12, 1570 to 1620 cm ^−1. Was mixed with 94 parts by mass of natural graphite powder of 19.9 cm ⁻¹ and 6 parts by mass of polyvinylidene fluoride, 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 so that the density of the negative electrode active material layer was 1.68 g / cm ³ to form a negative electrode.

[Production of positive electrode]
90 parts by mass of LiCoO ₂ , 4 parts by mass of carbon black and 6 parts by mass 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 an aluminum foil having a thickness of 15 μm, the positive electrode active material layer was pressed to a density of 3.2 g / cm ³ to obtain a positive electrode.

[Manufacture of electrolyte]
Under a dry argon atmosphere, a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (capacity ratio 20:40:40), 2 parts by weight of vinylene carbonate and tetraacetylethylenediamine (compound A6) as content in the non-aqueous electrolyte solution 0.5 parts by mass was mixed, and then sufficiently dried LiPF ₆ was dissolved so as to have a content ratio 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-shaped battery was manufactured and the high-temperature storage characteristics were evaluated. The evaluation results are shown in Table 1.

(Example 2)
To a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (capacity ratio 20:40:40), the content in the non-aqueous electrolyte is 2 parts by weight of vinylene carbonate, 0.5 parts by weight of fluoroethylene carbonate and tetraacetylethylenediamine ( 0.5 part by mass of the compound A6) was mixed. Subsequently, a sheet-like lithium secondary battery was produced in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried to a content ratio of 1.0 mol / liter was used. The high temperature storage characteristics were evaluated. The evaluation results are shown in Table 1.

Example 3
In a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (capacity ratio 20:40:40), the content in the non-aqueous electrolyte is 2 parts by weight of vinylene carbonate, 0.5 parts by weight of lithium difluorophosphate, and tetraacetylethylenediamine. (Compound A6) 0.5 parts by mass was mixed. Subsequently, a sheet-like lithium secondary battery was produced in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried to a content ratio of 1.0 mol / liter was used. The high temperature storage characteristics were evaluated. The evaluation results are shown in Table 1.

Example 4
In the electrolytic solution of Example 1, a sheet-like lithium secondary battery was obtained in the same manner as in Example 1 except that tetrakis (trifluoroacetyl) ethylenediamine (the compound A8) was used instead of tetraacetylethylenediamine (the compound A6). And the high temperature storage characteristics were evaluated. The evaluation results are shown in Table 1.

(Comparative Example 1)
To a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (capacity ratio 20:40:40), 2 parts by mass of vinylene carbonate was mixed as the content in the non-aqueous electrolyte. Subsequently, a sheet-like lithium secondary battery was produced in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ sufficiently dried to a content ratio of 1.0 mol / liter was used. The high temperature storage characteristics were evaluated. The evaluation results are shown in Table 1.

(Comparative Example 2)
A sheet-like lithium secondary battery was prepared in the same manner as in Example 1 except that tetramethylethylenediamine was used instead of tetraacetylethylenediamine (compound A6) in the electrolytic solution of Example 1, and evaluation of high-temperature storage characteristics was made. Went. The evaluation results are shown in Table 1.

表１から明らかなように、本発明に係る電池は、高温保存後のガス発生量が少なく、高温保存後の残存容量、回復容量に優れていることがわかる。

As is apparent from Table 1, the battery according to the present invention has a small amount of gas generated after high-temperature storage and is excellent in remaining capacity and recovery capacity after high-temperature storage.

  According to the present invention, a non-aqueous electrolyte battery having a high capacity and excellent storage characteristics can be provided, and the non-aqueous electrolyte battery can be reduced in size and performance.

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 one or more compounds represented by the following general formula (1). Non-aqueous electrolyte.

(In General Formula (1), R _{1 to} R ₄ are each independently an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, and 6 carbon atoms that may be substituted with a fluorine atom. A -12 aryl group or a C7-12 aralkyl group, X represents a C1-C12 divalent linking group optionally substituted with a fluorine atom.)   It contains at least one compound selected from the group consisting of a cyclic carbonate compound having a carbon-carbon unsaturated bond, a cyclic carbonate compound having a fluorine atom, a monofluorophosphate and a difluorophosphate. The non-aqueous electrolyte solution according to claim 1.   3. The non-carbon electrolyte compound having a carbon-carbon unsaturated bond is contained in the nonaqueous electrolytic solution in a proportion of 0.01% by mass or more and 8% by mass or less. Aqueous electrolyte.   4. A non-aqueous electrolyte battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution is a non-aqueous electrolyte solution according to claim 1. A non-aqueous electrolyte battery characterized by the above.