JP2002100399A - Non-aqueous electrolyte and lithium secondary battery using the same - Google Patents

Abstract

(57) [Abstract] [Problem] Cycle characteristics and electric capacity in a wide temperature range,
An object of the present invention is to provide a lithium secondary battery having excellent battery characteristics such as storage characteristics. SOLUTION: In an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent, the following general formula (I) is contained in the electrolytic solution. (Wherein, R ¹ represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group, or a hydrogen atom. In the formula, R ² and R ³ each independently represent It represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and R ² and R ³ are bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms. In the formula, Y ¹ represents —COOR ¹⁸ , —COR ¹⁸ or —SO ₂ R ¹⁸ , wherein each R ¹⁸ is independently an alkyl group having 1 to 12 carbon atoms, and 3 to 6 carbon atoms. Wherein n represents an integer of 1 or 2), wherein at least one of the alkyne derivatives represented by the formula (1) is contained. The present invention relates to a liquid and a lithium secondary battery using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel electrolyte for a lithium secondary battery which can provide a lithium secondary battery having excellent battery characteristics such as cycle characteristics, electric capacity and storage characteristics of the battery, and The present invention relates to a lithium secondary battery using the same.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries have been widely used as power sources for driving small electronic devices and the like. A lithium secondary battery is mainly composed of a positive electrode, a non-aqueous electrolyte, and a negative electrode. In particular, a lithium secondary battery using a lithium composite oxide such as LiCoO ₂ as a positive electrode and a carbon material or lithium metal as a negative electrode is used. It is preferably used. And
Examples of the electrolyte for the lithium secondary battery include ethylene carbonate (EC) and propylene carbonate (PC).
Such carbonates are preferably used.

[0003]

However, regarding the battery characteristics such as the cycle characteristics and the electric capacity of the battery,
There is a demand for a secondary battery having more excellent characteristics.
As the positive electrode active material, for example, LiCoO ₂ , LiMn ₂ O
_4. Lithium secondary batteries using LiNiO _{2 and the} like have a problem in that the solvent in the non-aqueous electrolyte partially oxidizes and decomposes at the time of charging, and the decomposition products hinder the desired electrochemical reaction of the battery. This results in reduced performance. This is thought to be due to electrochemical oxidation of the solvent at the interface between the positive electrode material and the non-aqueous electrolyte. Further, in a lithium secondary battery using a highly crystallized carbon material such as natural graphite or artificial graphite as the negative electrode active material, peeling of the carbon negative electrode material is observed, and the capacity may be irreversible depending on the degree of the phenomenon. . This peeling is caused by the decomposition of the solvent in the electrolytic solution at the time of charging, and is caused by the electrochemical reduction of the solvent at the interface between the carbon anode material and the electrolytic solution. Among them, an electrolytic solution using a PC having a low melting point and a high dielectric constant has high electric conductivity even at a low temperature, but when a graphite negative electrode is used, the decomposition of the PC occurs and cannot be used for a lithium secondary battery. There was a problem. Also, EC is partially decomposed during repeated charge and discharge, and the battery performance is reduced. Therefore, at present, the battery characteristics such as the cycle characteristics and the electric capacity of the battery are not always satisfactory.

The present invention solves the above-mentioned problems relating to the electrolyte solution for a lithium secondary battery, and provides a lithium battery having excellent cycle characteristics of a battery, and excellent battery characteristics such as electric capacity and storage characteristics in a charged state. An object of the present invention is to provide an electrolyte for a lithium secondary battery that can constitute a secondary battery, and a lithium secondary battery using the same.

[0005]

According to the present invention, there is provided an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent, wherein the electrolytic solution has the following general formula (I), (II), (III) or (IV): ,

[0006]

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[0007]

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[0008]

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[0009]

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(Wherein R¹, R^Four, R^Five, R⁶, R⁷, R⁸,
R⁹, R^Ten, R¹¹, R¹²And R¹⁷Are independent
Alkyl group having 1 to 12 carbon atoms, cyclo group having 3 to 6 carbon atoms
Represents an alkyl group, an aryl group, or a hydrogen atom. However
Then R^Four, R^Five, R⁶And R⁷Are simultaneously hydrogen atoms
And not. Where R^Two, R^Three, R¹³, R¹⁴, R^FifteenAnd R
¹⁶Is independently an alkyl group having 1 to 12 carbon atoms,
It represents a cycloalkyl group or an aryl group having 3 to 6 carbon atoms.
Also, R^TwoAnd R^Three, R^FourAnd R^Five, R⁶And R⁷, R¹³And R¹⁴, R
^FifteenAnd R¹⁶Are cycloalkyl having 3 to 6 carbon atoms bonded to each other
A kill group may be formed. Where Y¹Is -COO
R¹⁸, -COR¹⁸Or -SO_TwoR¹⁸, Y^TwoIs -COO
R¹⁹, -COR¹⁹Or -SO_TwoR¹⁹, Y^ThreeIs -COO
R²⁰, -COR²⁰Or -SO_TwoR²⁰, Y^FourIs -COO
R^{twenty one}, -COR^{twenty one}Or -SO_TwoR^{twenty one}, And Y^FiveIs-
COOR^{twenty two}, -COR^{twenty two}, -SO_TwoR^{twenty two}And R
¹⁸, R ¹⁹, R²⁰, R^{twenty one}And R^{twenty two}Are each independently
An alkyl group having 1 to 12 carbon atoms, a cycloalkyl having 3 to 6 carbon atoms
It represents an alkyl group or an aryl group. Where n is 1 or 2
Indicates an integer. ) Alkyne derivatives represented by
Lithium characterized by containing at least one kind
The present invention relates to an electrolyte for a secondary battery.

The present invention also provides a lithium secondary battery comprising a positive electrode, a negative electrode and an electrolyte in which an electrolyte is dissolved in a non-aqueous solvent, wherein the electrolyte has the following general formula (I) or (I)
I), (III), (IV),

[0012]

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[0013]

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[0014]

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[0015]

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(Wherein R¹, R^Four, R^Five, R⁶, R⁷, R⁸,
R⁹, R^Ten, R¹¹, R¹²And R¹⁷Are independent
Alkyl group having 1 to 12 carbon atoms, cyclo group having 3 to 6 carbon atoms
Represents an alkyl group, an aryl group, or a hydrogen atom. However
Then R^Four, R^Five, R⁶And R⁷Are simultaneously hydrogen atoms
And not. Where R^Two, R^Three, R¹³, R¹⁴, R^FifteenAnd R
¹⁶Is independently an alkyl group having 1 to 12 carbon atoms,
It represents a cycloalkyl group or an aryl group having 3 to 6 carbon atoms.
Also, R^TwoAnd R^Three, R^FourAnd R^Five, R⁶And R⁷, R¹³And R¹⁴, R
^FifteenAnd R¹⁶Are cycloalkyl having 3 to 6 carbon atoms bonded to each other
A kill group may be formed. Where Y¹Is -COO
R¹⁸, -COR¹⁸Or -SO_TwoR¹⁸, Y^TwoIs -COO
R¹⁹, -COR¹⁹Or -SO_TwoR¹⁹, Y^ThreeIs -COO
R²⁰, -COR²⁰Or -SO_TwoR²⁰, Y^FourIs -COO
R^{twenty one}, -COR^{twenty one}Or -SO_TwoR^{twenty one}, And Y^FiveIs-
COOR^{twenty two}, -COR^{twenty two}, -SO_TwoR^{twenty two}And R
¹⁸, R ¹⁹, R²⁰, R^{twenty one}And R^{twenty two}Are each independently
An alkyl group having 1 to 12 carbon atoms, a cycloalkyl having 3 to 6 carbon atoms
It represents an alkyl group or an aryl group. Where n is 1 or 2
Indicates an integer. ) Alkyne derivatives represented by
Lithium characterized by containing at least one kind
Related to secondary batteries.

The alkyne derivative contained in the electrolytic solution is reductively decomposed on the surface of the carbon negative electrode during charging before the organic solvent in the electrolytic solution, and a part of the decomposed product is, for example, natural graphite or artificial graphite. It is presumed that by forming a passivation film on the surface of the carbon negative electrode highly crystallized by the above activity, the reductive decomposition of the organic solvent in the electrolytic solution is prevented beforehand. Further, a part of the decomposition product is oxidatively decomposed before the organic solvent in the electrolytic solution in a minute overvoltage portion where the potential of the positive electrode material surface becomes excessively high, and the oxidative decomposition of the organic solvent in the electrolytic solution is performed. It is presumed to prevent this. This is considered to have an effect of suppressing the decomposition of the electrolyte solution without impairing the normal reaction of the battery.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The above-mentioned general formulas (I), (II) and (II) contained in an electrolytic solution in which an electrolyte is dissolved in a non-aqueous solvent
In the alkyne derivatives represented by (III) and (IV), R ¹ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ ,
R ¹¹ , R ¹² and R ¹⁷ each independently represent a methyl group,
An alkyl group having 1 to 12 carbon atoms such as an ethyl group, a propyl group, a butyl group, a pentyl group and a hexyl group is preferred.
The alkyl group may be a branched alkyl group such as an isopropyl group and an isobutyl group. Further, a cycloalkyl group having 3 to 6 carbon atoms such as a cyclopropyl group and a cyclohexyl group may be used. Further, those containing an aryl group having 6 to 12 carbon atoms such as a phenyl group, a benzyl group and a p-tolyl group may be used. Further, it may be a hydrogen atom. Where R ⁴ ,
R ⁵ , R ⁶ and R ⁷ are not simultaneously hydrogen atoms. Wherein R ² , R ³ , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are
Each independently having 1 to 1 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl;
Two alkyl groups are preferred. The alkyl group may be a branched alkyl group such as an isopropyl group and an isobutyl group. Further, a cycloalkyl group having 3 to 6 carbon atoms such as a cyclopropyl group and a cyclohexyl group may be used. Further, a phenyl group, a benzyl group, a p-tolyl group and the like having 6 to 12 carbon atoms.
May be those containing an aryl group.

Further, the compounds represented by the general formulas (I), (II) and (I)
Y in the alkyne derivative represented by II)¹, Y^Two, Y
^Three, Y^FourAnd Y^FiveIn, R¹⁸, R¹⁹, R²⁰, R^{twenty one}You
And R^{twenty two}Are each independently a methyl group, an ethyl group,
Such as ropyl, butyl, pentyl, hexyl
An alkyl group having 1 to 12 carbon atoms is preferred. The alkyl group is
Branched alkyl groups such as isopropyl and isobutyl
May be. In addition, cyclopropyl group, cyclohexyl group
And a cycloalkyl group having 3 to 6 carbon atoms such as Ma
Charcoal such as phenyl, benzyl, p-tolyl
It may contain an aryl group having a prime number of 6 to 12. Ma
R^TwoAnd R^Three, R^FourAnd R^Five, R⁶And R⁷, R ¹³And R¹⁴, R^Fifteen
And R¹⁶Are bonded to each other to form a cyclopropyl group,
Forming a tyl, cyclopentyl or cyclohexyl group
May be. Here, n represents an integer of 1 or 2.

As a specific example of the alkyne derivative represented by the general formula (I), for example, when Y ¹ = —COOR ¹⁸ , 1,1-dimethyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ^{1 2} = R ³ = methyl group, R ¹⁸ = methyl group, n = 1], 1,1-diethyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ² = R ³ = ethyl group, R ¹⁸ = methyl Group, n = 1], 1,1-ethylmethyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ² = ethyl group, R ³ = methyl group, R ¹⁸ = methyl group,
n = 1], 1,1-isobutylmethyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ² = isobutyl group, R ³ = methyl group, R ¹⁸ = methyl group, n = 1], 1,
1-dimethyl-2-butynylmethyl carbonate [R ¹
= R ² = R ³ = methyl group, R ¹⁸ = methyl group, n = 1], 1
-Ethynylcyclohexylmethyl carbonate [R ¹ =
Hydrogen atom, R ² and R ³ are bonded = pentamethylene group, R ¹⁸ =
Methyl group, n = 1], 1,1-phenylmethyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ² = phenyl group, R ³ = methyl group, R ¹⁸ = methyl group, n =
1], 1,1-diphenyl-2-propynylmethyl carbonate [R ¹ = hydrogen atom, R ² = R ³ = phenyl group, R
¹⁸ = methyl group, n = 1], 1,1-dimethyl-2-propynylethyl carbonate [R ¹ = hydrogen atom, R ² = R ³
= Methyl group, R ¹⁸ = ethyl group, n = 1]. When Y ¹ = —COR ¹⁸ , 1,1-dimethyl acetate-
2-propynyl [R ¹ = hydrogen atom, R ² = R ³ = methyl group, R ¹⁸ = methyl group, n = 1], 1,1-diethyl-2-propynyl acetate [R ¹ = hydrogen atom, R ² = R ³ = ethyl group, R ¹⁸ = methyl group, n = 1], 1,1-ethylmethyl-2-propynyl acetate [R ¹ = hydrogen atom, R ² = ethyl group, R ³ = methyl group, R ¹⁸ = Methyl group, n = 1], 1,1-isobutylmethyl-2-propynyl acetate [R ¹ = hydrogen atom, R ² = isobutyl group, R ³ = methyl group, R ¹⁸ = methyl group, n = 1], acetic acid 1,1-dimethyl-2-butynyl [R ¹ = R ² = R ³ = methyl group, R ¹⁸ = methyl group, n =
1], 1-ethynylcyclohexyl acetate [R ¹ = hydrogen atom, R ² and R ³ bond = pentamethylene group, R ¹⁸ = methyl group, n = 1], 1,1-phenylmethyl-2-propynyl acetate [ R ¹ = hydrogen atom, R ² = phenyl group, R ³ = methyl group, R ¹⁸ = methyl group, n = 1], 1,1-diphenyl-2-propynyl acetate [R ¹ = hydrogen atom, R ² = R ³ = phenyl group, R ¹⁸ = methyl group, n = 1], 1,1-dimethyl-2-propynyl propionate [R ¹ = hydrogen atom,
R ² = R ³ = methyl group, R ¹⁸ = ethyl group, n = 1]. When Y ¹ = —SO ₂ R ¹⁸ , 1,1-dimethyl-2-propynyl methanesulfonate [R ¹ = hydrogen atom, R ² = R ³ = methyl group, R ¹⁸ = methyl group, n = 1],
1,1-diethyl-2-propynyl methanesulfonate [R ¹ = hydrogen atom, R ² = R ³ = ethyl group, R ¹⁸ = methyl group, n = 1], 1,1-ethylmethyl-2 methanesulfonate -Propynyl [R ¹ = hydrogen atom, R ² = ethyl group, R
³ = methyl group, R ¹⁸ = methyl group, n = 1], 1,1-isobutylmethyl-2-propynyl methanesulfonate [R
¹ = hydrogen atom, R ² = isobutyl group, R ³ = methyl group, R
¹⁸ = methyl group, n = 1], 1,1-dimethyl-2-butynyl methanesulfonate [R ¹ = R ² = R ³ = methyl group, R
¹⁸ = methyl group, n = 1], 1-ethynylcyclohexyl methanesulfonate [R ¹ = hydrogen atom, R ² and R ³ are bonded =
Pentamethylene group, R ¹⁸ = methyl group, n = 1], 1,1-phenylmethyl-2-propynyl methanesulfonate [R ¹ = hydrogen atom, R ² = phenyl group, R ³ = methyl group,
R ^{1 8} = methyl, n = 1], methanesulfonic acid 1,1
Diphenyl-2-propynyl [R ¹ = hydrogen atom, R ² = R
³ = phenyl group, R ¹⁸ = methyl group, n = 1], 1,1-dimethyl-2-propynyl ethanesulfonate [R ¹ = hydrogen atom, R ² = R ³ = methyl group, R ¹⁸ = ethyl group, n =
1]. However, the present invention is not limited to these compounds at all.

Alkyne derivative represented by the general formula (II)
As a specific example of the conductor, for example, Y^Two= -COOR¹⁹And
And Y^Three= -COOR²⁰In the case of 3-hexyne-2,5-
Diol dimethyl dicarbonate [R^Four= R⁶= Methyl
Group, R^Five= R⁷= Hydrogen atom, R ¹⁹= R²⁰= Methyl group, n =
1], 3-hexyne-2,5-diol diethyldica
-Bonate [R^Four= R⁶= Methyl group, R^Five= R⁷= Hydrogen source
Child, R¹⁹= R²⁰= Ethyl group, n = 1], 2,5-dimethyl
Ru-3-hexyne-2,5-diol dimethyl dicar
Bonate [R^Four= R^Five= R⁶= R⁷= Methyl group, R¹⁹= R²⁰
= Methyl group, n = 1], 2,5-dimethyl-3-hexy
-2,5-diol diethyl dicarbonate [R^Four
= R^Five= R⁶= R⁷= Methyl group, R¹⁹= R²⁰= Ethyl group,
n = 1]. Y^Two= -COR¹⁹And Y^Three
= -COR²⁰In the case of 3-hexyne-2,5-diol
 Diacetate [R^Four= R⁶= Methyl group, R^Five= R⁷= Hydrogen
Atom, R¹⁹= R²⁰= Methyl group, n = 1], 3-hexyne
-2,5-diol dipropionate [R^Four= R⁶= Me
Tyl group, R^Five= R⁷= Hydrogen atom, R¹⁹= R²⁰= Ethyl group,
n = 1], 2,5-dimethyl-3-hexyne-2,5-
Diol diacetate [R^Four= R^Five= R⁶= R⁷= Methyl
Group, R¹⁹= R²⁰= Methyl group, n = 1], 2,5-dimethyl
Ru-3-hexyne-2,5-diol dipropione
G [R^Four= R^Five= R ⁶= R⁷= Methyl group, R¹⁹= R²⁰= Echi
And n = 1]. Y^Two= -SO_TwoR¹⁹You
And Y^Three= -SO_TwoR²⁰In the case of 3-hexyne-2,5-
Diol dimethane sulfonate [R^Four= R⁶= Methyl group,
R^Five= R⁷= Hydrogen atom, R¹⁹= R ²⁰= Methyl group, n =
1], 3-hexyne-2,5-diol diethanesul
Honate [R^Four= R⁶= Methyl group, R^Five= R⁷= Hydrogen atom,
R¹⁹= R²⁰= Ethyl group, n = 1], 2,5-dimethyl-
3-hexyne-2,5-diol dimethanesulfone
G [R^Four= R^Five= R⁶= R⁷= Methyl group, R¹⁹= R²⁰= Met
Group, n = 1], 2,5-dimethyl-3-hexyne-
2,5-diol diethane sulfonate [R^Four= R^Five=
R⁶= R⁷= Methyl group, R¹⁹= R²⁰= Ethyl group, n = 1]
And the like. However, the present invention relates to these compounds.
It is not limited at all.

Alkyne represented by the general formula (III)
As a specific example of the derivative, for example, Y ^Four= -COOR^{twenty one}You
And Y^Five= -COOR^{twenty two}In the case of 2,4-hexadiyne
-1,6-diol dimethyl dicarbonate [R⁸=
R⁹= R^Ten= R¹¹= Hydrogen atom, R ^{twenty one}= R^{twenty two}= Methyl group,
n = 1], 2,4-hexadiyne-1,6-diol
Diethyl dicarbonate [R⁸= R⁹= R^Ten= R¹¹= Hydrogen
Atom, R^{twenty one}= R^{twenty two}= Ethyl group, n = 1], 2,7-dimethyl
Cyl-3,5-octadiyne-2,7-diol dimethyl
Lujicarbonate [R⁸= R⁹= R^Ten= R¹¹= Methyl group,
R^{twenty one}= R^{twenty two}= Methyl group, n = 1], 2,7-dimethyl-
3,5-octadiyne-2,7-diol diethyldica
-Bonate [R⁸= R⁹= R^Ten= R¹¹= Methyl group, R^{twenty one}=
R^{twenty two}= Ethyl group, n = 1]. Y^Four= −
COR^{twenty one}And Y^Five= -COR^{twenty two}In the case of 2,4-hex
Sadiin-1,6-diol diacetate [R⁸= R⁹
= R ^Ten= R¹¹= Hydrogen atom, R^{twenty one}= R^{twenty two}= Methyl group, n =
1], 2,4-hexadiyne-1,6-diol dip
Lopionate [R⁸= R⁹= R^Ten= R¹¹= Hydrogen atom, R ^{twenty one}
= R^{twenty two}= Ethyl group, n = 1], 2,7-dimethyl-3,
5-octadiyne-2,7-diol diacetate
[R⁸= R⁹= R^Ten= R¹¹= Methyl group, R^{twenty one}= R^{twenty two}= Met
Group, n = 1], 2,7-dimethyl-3,5-octadi
In-2,7-diol dipropionate [R⁸= R⁹
= R^Ten= R¹¹= Methyl group, R^{twenty one}= R^{twenty two}= Ethyl group, n =
1]. Y^Four= -SO_TwoR^{twenty one}And Y^Five=
-SO_TwoR^{twenty two}In the case of 2,4-hexadiyne-1,6-
Diol dimethanesulfonate [R ⁸= R⁹= R^Ten= R
¹¹= Hydrogen atom, R^{twenty one}= R^{twenty two}= Methyl group, n = 1], 2,
4-hexadiyne-1,6-diol diethanesulfo
Nate [R⁸= R⁹= R^Ten= R¹¹= Hydrogen atom, R^{twenty one}= R^{twenty two}
= Ethyl group, n = 1], 2,7-dimethyl-3,5-o
Kutadiyne-2,7-diol dimethanesulfonate
[R⁸= R⁹= R^Ten= R¹¹= Methyl group, R^{twenty one}= R^{twenty two}= Met
Group, n = 1], 2,7-dimethyl-3,5-octadi
In-2,7-diol diethanesulfonate [R⁸
= R⁹= R^Ten= R¹¹= Methyl group, R^{twenty one}= R^{twenty two}= Ethyl
Group, n = 1]. However, the present invention
The compounds are not limited at all.

Alkyne derivative represented by the general formula (IV)
Specific examples of the conductor include, for example, di (1,1-dimethyl
-2-propynyl) carbonate [R¹²= R¹⁷= Hydrogen source
Child, R¹³= R¹⁴= R^Fifteen= R¹⁶= Methyl group, n = 1], di
(1,1-diethyl-2-propynyl) carbonate
[R¹²= R¹⁷= Hydrogen atom, R¹³= R¹⁴= R^Fifteen= R¹⁶= D
Tyl group, n = 1], di (1,1-ethylmethyl-2-propyl)
Ropinyl) carbonate [R¹²= R¹⁷= Hydrogen atom, R¹³
= R^Fifteen= Ethyl group, R¹⁴= R¹⁶= Methyl group, n = 1],
Di (1,1-isobutylmethyl-2-propynyl) car
Bonate [R¹²= R¹⁷= Hydrogen atom, R¹³= R^Fifteen= Isobu
Tyl group, R¹⁴= R¹⁶= Methyl group, n = 1], di (1,1
-Dimethyl-2-butynyl) carbonate [R¹²= R¹⁷
= R¹³= R ¹⁴= R^Fifteen= R¹⁶= Methyl group, n = 1], di
(1-ethynylcyclohexyl) carbonate [R¹²=
R¹⁷= Hydrogen atom, R¹³And R¹⁴Is a bond = pentamethylene
Group, R^FifteenAnd R¹⁶Is a bond = pentamethylene group, n = 1] is
No. However, the present invention is not limited to these compounds.
It is not specified.

In the alkyne derivative, if the content of the alkyne derivative represented by the general formulas (I), (II), (III), and (IV) is excessively large, the conductivity of the electrolytic solution and the like change. Battery performance may decrease,
If the amount is excessively small, a sufficient film is not formed and the expected battery characteristics cannot be obtained.
A range of 1 to 20% by weight, particularly 0.1 to 10% by weight is preferred.

The non-aqueous solvent used in the present invention is preferably a solvent composed of a high dielectric constant solvent and a low viscosity solvent. Examples of the high dielectric constant solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC).
Preferred examples thereof include cyclic carbonates. One of these high dielectric constant solvents may be used, or two or more thereof may be used in combination.

Examples of the low viscosity solvent include dimethyl carbonate (DMC) and methyl ethyl carbonate (M
EC), chain carbonates such as diethyl carbonate (DEC), tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane And lactones such as γ-butyrolactone, nitriles such as acetonitrile, esters such as methyl propionate, and amides such as dimethylformamide. These low-viscosity solvents may be used alone or in combination of two or more. The high dielectric constant solvent and the low viscosity solvent are each arbitrarily selected and used in combination. The high dielectric constant solvent and the low viscosity solvent are used in a volume ratio (high dielectric constant solvent: low viscosity solvent) of usually 1: 9 to 4: 1, preferably 1: 4 to 7: 3. You.

As the electrolyte used in the present invention, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiN (S
O ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂
CF ₃ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₃ (C ₂ F ₅ )
₃ , LiPF ₃ (CF ₃ ) ₃ , LiPF ₃ (iso-C
_{3 F 7) 3, LiPF 5} (iso-C 3 F 7) , and the like. These electrolytes may be used alone or in combination of two or more. These electrolytes are
The non-aqueous solvent is usually 0.1 to 3 M, preferably 0.5 to 3 M.
It is used after being dissolved at a concentration of ~ 1.5M.

The electrolytic solution of the present invention is prepared, for example, by mixing the above-mentioned high-dielectric solvent or low-viscosity solvent, dissolving the above-mentioned electrolyte therein, and mixing the above-mentioned general formulas (I), (II), (III), (I
It is obtained by dissolving at least one of the alkyne derivatives represented by V).

[0029] The electrolyte of the present invention comprises a constituent member of a secondary battery,
In particular, it is suitably used as a component of a lithium secondary battery. The constituent members other than the electrolytic solution constituting the secondary battery are not particularly limited, and various conventionally used constituent members can be used.

For example, as the positive electrode active material, a composite metal oxide of lithium and at least one metal selected from the group consisting of cobalt, manganese, nickel, chromium, iron and vanadium is used. Examples of such a composite metal oxide include LiCoO ₂ , LiMn ₂ O ₄ ,
LiNiO _{2 and the} like.

For the positive electrode, a conductive agent such as acetylene black or carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or a copolymer of styrene and butadiene (S
BR), a copolymer of acrylonitrile and butadiene (N
After kneading with a binder such as BR) and carboxymethylcellulose (CMC) to form a positive electrode mixture, this positive electrode material is rolled into a foil or lath plate made of aluminum or stainless steel as a current collector, and heated to 50 ° C. It is manufactured by performing a heat treatment under a vacuum at a temperature of about 250 ° C. for about 2 hours.

As the negative electrode (negative electrode active material), a lithium metal, a lithium alloy, and a carbon material having a graphite type crystal structure capable of occluding and releasing lithium [pyrolytic carbons, cokes, graphites (artificial graphite, natural graphite) Graphite, etc.),
Organic polymer compound combustion body, carbon fiber] and composite tin oxide. In particular, it is preferable to use a carbon material having a graphite-type crystal structure in which the plane spacing (d ₀₀₂ ) of the lattice plane (002) is 0.335 to 0.340 nm (nanometers). The powder material such as carbon material is ethylene propylene diene terpolymer (EPD).
M), binders such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), copolymer of styrene and butadiene (SBR), copolymer of acrylonitrile and butadiene (NBR), and carboxymethylcellulose (CMC) And used as a negative electrode mixture.

The structure of the lithium secondary battery is not particularly limited, and may be a coin-type battery or a polymer battery having a single or multiple layers of a positive electrode, a negative electrode, a separator, a roll-shaped positive electrode, a negative electrode, and a roll-shaped battery. Examples include a cylindrical battery and a prismatic battery having a separator. As the separator, a known microporous polyolefin membrane, woven fabric, nonwoven fabric, or the like is used.

[0034]

Next, the present invention will be described with reference to Examples and Comparative Examples.
Is specifically described. Example 1 [Preparation of electrolytic solution] EC / DEC (volume ratio) = 1/2
A water solvent was prepared and LiPF₆To a concentration of 1M
After preparing the electrolyte by dissolving
1,1-dimethyl-2-propynylmethylca as a conductor
-Bonate [Y in the general formula (I) ¹= -COOR¹⁸, R¹
= Hydrogen atom, R^Two= R^Three= Methyl group, R¹⁸= Methyl group, n
= 1] was added to the electrolyte solution so as to be 2% by weight.

[Preparation of Lithium Secondary Battery and Measurement of Battery Characteristics] LiCoO ₂ (positive electrode active material) was 80% by weight, acetylene black (conductive agent) was 10% by weight, and polyvinylidene fluoride (binder) was 10% by weight. %, And 1-methyl-2-pyrrolidone was added to the mixture to form a slurry, which was applied on an aluminum foil. Thereafter, it was dried and molded under pressure to prepare a positive electrode. 90% by weight of artificial graphite (negative electrode active material) and 10% by weight of polyvinylidene fluoride (binder) were mixed, and 1-methyl-2-pyrrolidone was added thereto to form a slurry to form a slurry on a copper foil. Applied. Thereafter, this was dried and molded under pressure to prepare a negative electrode. Then, using a separator made of a polypropylene microporous film, the above-mentioned electrolytic solution was injected into the coin battery (diameter 20 m).
m, 3.2 mm in thickness). Using this coin battery, the battery was charged to a final voltage of 4.2 V in 5 hours at room temperature (20 ° C.) at a constant current and a constant voltage of 0.8 mA.
Under a constant current of 8 mA, the battery was discharged to a final voltage of 2.7 V, and this charge / discharge was repeated. Initial discharge capacity is 1M LiPF
₆ + EC / DEC (volume ratio) = 1/2 was calculated as the relative capacity as compared with the case where the electrolyte was used (Comparative Example 1), and was 1.03. When the battery characteristics after 50 cycles were measured, the discharge capacity retention ratio when the initial discharge capacity was 100% was 92.2%. Also, the low-temperature characteristics were good. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 2 A non-aqueous solvent having EC / DEC (volume ratio) = 1/2 was prepared.
LiPF ₆ was dissolved therein to a concentration of 1 M to prepare an electrolytic solution, and further, as an alkyne derivative, 1,1-ethylmethyl-2-propynyl acetate [general formula (I)
In the formula, Y ¹ = —COR ¹⁸ , R ¹ = hydrogen atom, R ² = ethyl group, R ³ = methyl group, R ¹⁸ = methyl group, n = 1] so as to be 2% by weight based on the electrolyte. added. Using this electrolytic solution, a coin battery was prepared in the same manner as in Example 1, and the battery characteristics were measured. The initial discharge capacity was 1 M LiPF
₆ + EC / DEC (volume ratio) = 1/2 was calculated as a relative capacity as compared with the case where the electrolyte was used (Comparative Example 1), and was 1.02. When the battery characteristics after 50 cycles were measured, the discharge capacity retention ratio when the initial discharge capacity was 100% was 91.5%. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 3 A non-aqueous solvent of PC / EC / DEC (volume ratio) = 1/2/7 was prepared, and LiPF ₆ was dissolved in the non-aqueous solvent to a concentration of 1 M to prepare an electrolyte. And 1,1-diethyl-2-propynyl methanesulfonate as an alkyne derivative [in the general formula (I), Y ¹ = —SO ₂ R ¹⁸ , R ¹ = hydrogen atom, R ² = R ³ = ethyl group, R ¹⁸ = methyl group, n = 1] was used in the same manner as in Example 1 except that 2% by weight of the electrolytic solution was used to prepare a coin battery, and the battery characteristics were measured. Was 50%, and the battery capacity after 50 cycles was measured. As a result, the discharge capacity retention ratio was 91.9%. Also, the low-temperature characteristics were good. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 4 As an alkyne derivative, 2,5-dimethyl-3-hexyne-2,5-diol diethyldicarbonate [in the general formula (II), Y ² = Y ³ = -COOR ¹⁹ = -COOR ²⁰ ;
R ⁴ = R ⁵ = R ⁶ = R ⁷ = methyl group, R ¹⁹ = R ²⁰ = ethyl group, n = 1] except that 1% by weight of the electrolytic solution was used. When the battery was fabricated and the battery characteristics were measured, the relative capacity of the initial discharge capacity was 1.02, and the battery characteristics after 50 cycles were measured. As a result, the discharge capacity retention ratio was 91.1%. Also, the low-temperature characteristics were good. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 5 As an alkyne derivative, 3-hexyne-2,5-diol dimethanesulfonate [in the general formula (II), Y ² = Y ^{3
_{= -SO 2 R 19 = -SO 2}} R 20, R 4 = R 6 = methyl radical, R
⁵ = R ⁷ = hydrogen atom, R ¹⁹ = R ²⁰ = methyl group, n = 1] except that 1% by weight of the electrolytic solution was used, a coin battery was fabricated in the same manner as in Example 3, and the battery characteristics were measured. As a result, the relative capacity of the initial discharge capacity was 1.03, and the battery characteristics after 50 cycles were measured.
1.6%. Also, the low-temperature characteristics were good. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 6 A non-aqueous solvent of PC / EC / MEC (volume ratio) = 1/2/7 was prepared, and LiPF ₆ was dissolved in the non-aqueous solvent to a concentration of 1 M to prepare an electrolytic solution. And 2,4-hexadiyne-1,6-diol dimethyl dicarbonate as an alkyne derivative [in the general formula (III), Y ⁴ = Y ⁵ = −
COOR ²¹ = -COOR ²² , R ⁸ = R ⁹ = R ¹⁰ = R ¹¹ = hydrogen atom, R ²¹ = R ²² = methyl group, n = 1] except that 1% by weight of the electrolyte was used. An electrolytic solution was prepared in the same manner as in Example 1 to prepare a coin battery, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.02, and the battery characteristics after 50 cycles were measured. The rate was 91.8%. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 7 As an alkyne derivative, 2,4-hexadiyne-1,6-
Diol dimethanesulfonate [general formula (III)
Where Y ⁴ = Y ⁵ = -SO ₂ R ²¹ = -SO ₂ R ²² , R ⁸ = R ⁹ =
R ¹⁰ = R ¹¹ = hydrogen atom, R ²¹ = R ²² = methyl group, n =
Example 6 except that 1) was used in an amount of 1% by weight based on the electrolyte.
A coin battery was prepared in the same manner as described above, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.03, and the battery characteristics after 50 cycles were measured. The discharge capacity retention ratio was 91.5%. there were. Also, the low-temperature characteristics were good. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 8 PC / EC / DMC / DEC (capacity ratio) = 1/2/3 /
After preparing a non-aqueous solvent of No. 4 and dissolving LiPF ₆ to a concentration of 1 M to prepare an electrolytic solution, di (1,1-dimethyl-2-propynyl) carbonate [general In the formula (IV), R ¹² = R ¹⁷ = hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R ¹⁶ = methyl group, n = 1]
Example 1 except for using 0.5% by weight of
An electrolytic solution was prepared in the same manner as in Example 1 to prepare a coin battery, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.0%.
3, and the battery capacity after 50 cycles was measured. As a result, the discharge capacity retention ratio was 92.6%. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 9 As a positive electrode active material, LiMn ₂ O ₄ was used instead of LiCoO _2.
A coin battery was prepared by preparing an electrolytic solution in the same manner as in Example 3 except for using, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 0.83. Upon measurement, the discharge capacity retention ratio was 93.1.
%Met. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Example 10 As a positive electrode active material, LiCo _0.1 N was used instead of LiCoO _2.
Using i _0.9 O ₂ , di (1,1-
Dimethyl-2-propynyl) carbonate [General formula (I
In V), R ¹² = R ¹⁷ = hydrogen atom, R ¹³ = R ¹⁴ = R ¹⁵ = R
¹⁶ = methyl group, n = 1] is 0.5% by weight based on the electrolytic solution.
Except for the use, an electrolytic solution was prepared in the same manner as in Example 3 to prepare a coin battery, and the battery characteristics were measured. The relative capacity of the initial discharge capacity was 1.19, and the battery characteristics after 50 cycles were measured. As a result, the discharge capacity retention ratio was 90.5%.
Met. Table 1 shows the coin battery fabrication conditions and battery characteristics.
Shown in

Example 11 A coin battery was prepared by preparing an electrolytic solution in the same manner as in Example 8 except that natural graphite was used instead of artificial graphite as the negative electrode active material, and the battery characteristics were measured. The relative capacity of the capacity was 1.02, and the battery characteristics after 50 cycles were measured. As a result, the discharge capacity retention rate was 93.2%. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

Comparative Example 1 A non-aqueous solvent having EC / DEC (volume ratio) = 1/2 was prepared.
LiPF ₆ was dissolved therein to a concentration of 1M.
At this time, no alkyne derivative was added at all. Using this electrolytic solution, a coin battery was produced in the same manner as in Example 1,
Battery characteristics were measured. In this case, the relative capacity of the initial discharge capacity is 1. The discharge capacity retention rate after 50 cycles with respect to the initial discharge capacity was 82.8%. Table 1 shows the manufacturing conditions and battery characteristics of the coin battery.

[0047]

[Table 1]

The present invention is not limited to the above-described embodiments, and various combinations that can be easily inferred from the gist of the invention are possible. In particular, the combinations of the solvents in the above examples are not limited. Further, while the above embodiments relate to coin batteries, the present invention is also applicable to cylindrical and prismatic batteries.

[0049]

According to the present invention, it is possible to provide a lithium secondary battery having excellent battery characteristics such as cycle characteristics, electric capacity, and storage characteristics in a wide temperature range.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takayuki Hattori10, 1978 Kogushi, Oji, Ube City, Yamaguchi Prefecture Inside Ube Chemical Plant Ube Industries, Ltd. Ube Kosan Co., Ltd. Ube Chemical Factory F-term (reference) 5H029 AJ03 AJ04 AJ05 AK03 AL06 AL12 AM03 AM04 AM05 AM06 AM07 EJ11 HJ02

Claims (2)

[Claims] 1. An electrolysis in which an electrolyte is dissolved in a non-aqueous solvent.
In the solution, the following general formulas (I) and (I)
I), (III), (IV),Embedded imageEmbedded imageEmbedded image(Where R¹, R^Four, R^Five, R⁶, R⁷, R⁸, R⁹, R^Ten,
R¹¹, R¹²And R¹⁷Is each independently 1 to 1 carbon atoms
12 alkyl groups, a cycloalkyl group having 3 to 6 carbon atoms,
Represents an aryl group or a hydrogen atom. Where R^Four, R^Five,
R⁶And R⁷Are not simultaneously hydrogen atoms. formula
Medium, R^Two, R^Three, R¹³, R¹⁴, R^FifteenAnd R¹⁶Each
Each independently an alkyl group having 1 to 12 carbon atoms, 3 to 6 carbon atoms
And a cycloalkyl group and an aryl group. Also, R^TwoWhen
R^Three, R^FourAnd R^Five, R⁶And R⁷, R¹³And R¹⁴, R^FifteenAnd R
¹⁶Are bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms
May be formed. Where Y¹Is -COOR¹⁸,
-COR¹⁸Or -SO_TwoR¹⁸, Y^TwoIs -COOR¹⁹,
-COR¹⁹Or -SO_TwoR¹⁹, Y^ThreeIs -COOR²⁰,
-COR²⁰Or -SO_TwoR²⁰, Y^FourIs -COOR^{twenty one},
-COR^{twenty one}Or -SO_TwoR^{twenty one}, And Y^FiveIs -COO
R^{twenty two}, -COR^{twenty two}, -SO_TwoR^{twenty two}And R¹⁸, R
¹⁹, R²⁰, R^{twenty one}And R^{twenty two}Are carbon numbers independently
Alkyl group of 1 to 12, cycloalkyl of 3 to 6 carbon atoms
And an aryl group. Where n is an integer of 1 or 2
Is shown. )) Represented by at least
Lithium secondary battery characterized by containing one type
Electrolyte for pond. 2. An electrolyte dissolved in a positive electrode, a negative electrode and a non-aqueous solvent.
Lithium rechargeable battery composed of unsolved electrolyte
In the electrolytic solution, the following general formulas (I), (II) and (II)
I), (IV),Embedded imageEmbedded imageEmbedded image(Where R¹, R^Four, R^Five, R⁶, R⁷, R⁸, R⁹, R^Ten,
R¹¹, R¹²And R¹⁷Is each independently 1 to 1 carbon atoms
12 alkyl groups, a cycloalkyl group having 3 to 6 carbon atoms,
Represents an aryl group or a hydrogen atom. Where R^Four, R^Five,
R⁶And R⁷Are not simultaneously hydrogen atoms. formula
Medium, R^Two, R^Three, R¹³, R¹⁴, R^FifteenAnd R¹⁶Each
Each independently an alkyl group having 1 to 12 carbon atoms, 3 to 6 carbon atoms
And a cycloalkyl group and an aryl group. Also, R^TwoWhen
R^Three, R^FourAnd R^Five, R⁶And R⁷, R¹³And R¹⁴, R^FifteenAnd R
¹⁶Are bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms
May be formed. Where Y¹Is -COOR¹⁸,
-COR¹⁸Or -SO_TwoR¹⁸, Y^TwoIs -COOR¹⁹,
-COR¹⁹Or -SO_TwoR¹⁹, Y^ThreeIs -COOR²⁰,
-COR²⁰Or -SO_TwoR²⁰, Y^FourIs -COOR^{twenty one},
-COR^{twenty one}Or -SO_TwoR^{twenty one}, And Y^FiveIs -COO
R^{twenty two}, -COR^{twenty two}, -SO_TwoR^{twenty two}And R¹⁸, R
¹⁹, R²⁰, R^{twenty one}And R^{twenty two}Are carbon numbers independently
Alkyl group of 1 to 12, cycloalkyl of 3 to 6 carbon atoms
And an aryl group. Where n is an integer of 1 or 2
Is shown. )) Represented by at least
Lithium secondary battery characterized by containing one type
pond.