JP2013012442A - Electrode protective film forming agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for a lithium secondary battery or an electrolyte for a lithium-ion capacitor, which has high voltage and high capacity and is excellent in charge/discharge cycle performance and high-temperature storage characteristics.SOLUTION: An electrode protective film forming agent (A) contains a phosphoric ester compound (B) represented by general formula (1). [In the formula, T- Tare each independently an alkenyl group represented by specific general formula, a saturated hydrocarbon group having 1-12 carbon atoms, or an aromatic group having 6-12 carbon atoms, and at least one of T- Tis a substituent represented by specific general formula.]

Description

  The present invention relates to an electrode protective film forming agent useful for a lithium secondary battery or a lithium ion capacitor, and an electrolytic solution containing the electrode protective film forming agent.

  With the recent reduction in weight and size of electrical products, development of lithium secondary batteries having a high energy density is in progress. In addition, with the expansion of the application field of lithium secondary batteries, improvement of battery characteristics is also demanded.

As the positive electrode of the lithium secondary battery, lithium cobalt composite oxide such as LiCoO ₂ , lithium nickel composite oxide such as LiNiO ₂ , lithium manganese composite oxide such as LiMnO ₂ , and the like are used. In a lithium secondary battery using such a positive electrode material, a solvent such as ethylene carbonate or dimethylene carbonate is decomposed on the surface of the positive electrode, and oxidative decomposition products are deposited, thereby inhibiting the absorption of lithium cations in the positive electrode material. Therefore, there is a problem that the cycle characteristics are not sufficient due to the deterioration of the discharge load characteristics.

  Therefore, it has been proposed to contain various additives that are considered to act on the positive electrode in the electrolytic solution for the purpose of suppressing the oxidative decomposition of the solvent in the positive electrode and improving the cycle characteristics of the lithium secondary battery.

  Specifically, in Patent Document 1, by adding an aromatic sulfide such as methylphenyl sulfide or diphenyl sulfide, the aromatic sulfide is preferentially oxidized on the surface of the positive electrode over the electrolyte, and the oxidation product is converted into the negative electrode. It is disclosed that by repeating the reaction of diffusion and reduction to return to the original sulfide body, the oxidative decomposition of the solvent is suppressed, and the storage characteristics, charge / discharge cycle characteristics and the like are improved.

  In Patent Document 2, by adding a sulfide compound having an aryl group or a heterocyclic group as a substituent, this sulfide compound is preferentially applied to strongly oxidizing chemical species such as active oxygen generated on the surface of the positive electrode. It has been disclosed to suppress a decrease in discharge capacity due to repeated charge and discharge by reacting and suppressing oxidative decomposition of the solvent. Furthermore, it is disclosed that a part of the oxidized material adheres to the positive electrode, is reduced during discharge, returns to the original state, and a part is diffused to the negative electrode.

JP 7-320779 A Japanese Patent Laid-Open No. 10-64591

  However, the sulfide compounds as disclosed in Patent Documents 1 and 2 have a problem that themselves are decomposed into radicals and cycle characteristics are deteriorated by reaction with an electrolytic solution and an electrode.

The inventors of the present invention have arrived at the present invention as a result of studies to achieve the above object.
That is, the present invention relates to an electrode protective film-forming agent (A) containing a phosphate ester compound (B) represented by the following general formula (1); an electrolytic solution containing (A); Secondary battery or lithium ion capacitor.

[Wherein, T ^{1 to} T ³ are each independently an alkenyl group (a11) represented by the following general formula (2), an alkenyl group (a12) represented by the following general formula (3), or a carbon number of 1 to 12 A saturated hydrocarbon group or an aromatic group having 6 to 12 carbon atoms, and at least one of T ^{1 to} T ³ is a substituent represented by the following general formula (2) or the following general formula (3). It is a substituent represented. ]

[Wherein R ² is a direct bond or an alkylene group having 1 to 3 carbon atoms, and Q ¹ , Q ² and Q ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or a carbon number. It is a 1 or 2 fluoroalkyl group, a phenyl group, a cyano group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, or an alkoxycarbonyl group having 1 to 4 carbon atoms. ]

[Wherein R ³ is an alkylene group having 1 to ³ carbon atoms, Q ⁴ is a hydrogen atom or a halogen atom, and Q ⁵ , Q ⁶ and Q ⁷ are each independently a hydrogen atom, a halogen atom or a carbon number. An alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 or 2 carbon atoms, a phenyl group, a cyano group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, or an alkoxycarbonyl group having 1 to 4 carbon atoms. ]

  The electrode protective film forming agent (A) of the present invention can suppress the decomposition of the electrolytic solution on the electrode surface under a high voltage, and can improve the charge / discharge cycle characteristics and the high temperature storage characteristics.

Hereinafter, the present invention will be described in more detail.
The electrode protective film-forming agent (A) of the present invention comprises a phosphate ester compound (B) having at least one alkenyl group (a1) as an electropolymerizable site in the molecule as an essential component. Thereby, the cycle characteristics of the battery are greatly improved by forming a protective film on the positive electrode by electrolytic polymerization. Moreover, since it has many ester bonds, lithium ion conductivity is high and there is almost no increase in ion transfer resistance due to film formation.

Examples of the phosphoric acid ester compound (B) as an essential component in the present invention include the phosphoric acid ester compound (B) represented by the general formula (1) having at least one alkenyl group (a1).
T ^{1 to} T ³ in the general formula (1) are each independently an alkenyl group represented by the general formula (2), an alkenyl group represented by the general formula (3), or a saturated hydrocarbon group having 1 to 12 carbon atoms. Or an aromatic group having 6 to 12 carbon atoms, and at least one of T ^{1 to} T ³ is a substituent represented by the general formula (2) or a substituent represented by the general formula (3). .

  As a C1-C12 saturated hydrocarbon group in General formula (1), a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, n-pentyl group, isopentyl group , N-hexyl group, cyclohexyl group, n-octyl group, n-decyl group, n-dodecyl group and the like.

  Examples of the aromatic group having 6 to 12 carbon atoms in the general formula (1) include phenyl group, 4-methoxyphenyl group, 4-cyanophenyl group, 4-methylphenyl group, 2,4,6-trimethylphenyl group, and 4 -A phenylphenyl group etc. are mentioned.

  Examples of the alkenyl group (a1) of the general formula (1) include an alkenyl group (a11) represented by the general formula (2) or an alkenyl group (a12) represented by the general formula (3).

Examples of the alkylene group having 1 to 3 carbon atoms in the general formula (2) include a methylene group, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group. The case of direct connection is a case where the phosphate group and the alkenyl group are directly connected without interposing R ² as a connecting group. Among these, from the viewpoint of charge / discharge cycle characteristics, a direct bond or a methylene group is preferable, and a case where a phosphate ester group and an alkenyl group are directly connected is more preferable.

Examples of the alkyl group having 1 to 4 carbon atoms in the general formula (2) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group.

As a halogen atom in General formula (2), a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.
Examples of the fluoroalkyl group having 1 or 2 carbon atoms include those in which 1 to 5 hydrogen atoms on a methyl group or an ethyl group are substituted with fluorine atoms, such as a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, Examples thereof include a fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, a tetrafluoroethyl group, and a pentafluoroethyl group.

As a C1-C3 alkoxy group in General formula (2), a methoxy group, an ethoxy group, n-propoxy group, an isopropoxy group, etc. are mentioned.
Examples of the alkoxycarbonyl group having 1 to 4 carbon atoms include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, and an isopropoxycarbonyl group.

Examples of the alkenyl group (a11) represented by the general formula (2) include vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, isobutenyl group, and 1-pentenyl. Group, 2-pentenyl group, 3-pentenyl group, isopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group and isohexenyl group.
Preferred combinations of R ² , Q ¹ , Q ² and Q ³ include the following (1) to (6).
(1) R ² = directly connected, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = hydrogen atom (2) R ² = directly connected, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = methyl group (3) R ² = directly connected, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = ethyl group (4) R ² = directly connected, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = phenyl group (5) R ² = methylene group, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = ethoxy group (6) R ² = methylene group, Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = Ethoxycarbonyl group Among these combinations, a vinyl group or 1-propenyl group which is a combination of (1) or (2) is more preferable.

一般式（３）におけるＲ³ は炭素数１〜３のアルキレン基であり、Ｑ^４は水素原子又はハロゲン原子であり、Ｑ^５、Ｑ^６及びＱ^７は、それぞれ独立に水素原子、ハロゲン原子、炭素数１〜４のアルキル基、炭素数１若しくは２のフルオロアルキル基、フェニル基、シアノ基、カルボキシル基、炭素数１〜３のアルコキシ基又は炭素数１〜４のアルコキシカルボニル基である。

R ³ in the general formula (3) is an alkylene group having 1 to ³ carbon atoms, Q ⁴ is a hydrogen atom or a halogen atom, and Q ⁵ , Q ⁶ and Q ⁷ are each independently a hydrogen atom, a halogen atom, An alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 or 2 carbon atoms, a phenyl group, a cyano group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, or an alkoxycarbonyl group having 1 to 4 carbon atoms.

  Examples of the alkylene group having 1 to 3 carbon atoms in the general formula (3) include a methylene group, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group. Among these, an ethylene group is preferable from the viewpoint of charge / discharge cycle characteristics.

  As a C1-C4 alkyl group in General formula (3), a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, and t-butyl group are mentioned.

As a halogen atom in General formula (3), a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.
Examples of the fluoroalkyl group having 1 or 2 carbon atoms in the general formula (3) include those in which 1 to 5 hydrogen atoms on a methyl group or an ethyl group are substituted with fluorine atoms, and a fluoromethyl group or a difluoromethyl group. Trifluoromethyl group, fluoroethyl group, difluoroethyl group, trifluoroethyl group, tetrafluoroethyl group, pentafluoroethyl group and the like.

As a C1-C3 alkoxy group in General formula (3), a methoxy group, an ethoxy group, n-propoxy group, an isopropoxy group, etc. are mentioned.
Examples of the alkoxycarbonyl group having 1 to 4 carbon atoms include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, and an isopropoxycarbonyl group.

As preferred combinations of R ³ , Q ⁴ , Q ⁵ , Q ⁶ and Q ^{7 in} the general formula (3), the following (1) to (6) may be mentioned.
(1) R ³ = methylene group, Q ⁴ = fluorine atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = hydrogen atom (2) R ³ = methylene group, Q ⁴ = fluorine atom, Q ⁵ = Hydrogen atom, Q ⁶ = methyl group, Q ⁷ = hydrogen atom (3) R ³ = methylene group, Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = hydrogen atom (4) R ³ = methylene group, Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = methyl group (5) R ³ = methylene group, Q ⁴ = fluorine atom, Q ⁵ = hydrogen atom, Q ⁶ = ethoxy group, Q ⁷ = hydrogen atom (6) R ³ = methylene group, Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = ethoxycarbonyl group, Q ⁷ = hydrogen atom Among these combinations, further The combination of (1) is preferable.

  Specific examples of the phosphate ester compound (B) include trivinyl phosphate, tris phosphate (1-propenyl), tris phosphate (1-butenyl), phosphate (1-propenyl) divinyl, and phosphate (1-butenyl). ) Divinyl, bis (1-propenyl) vinyl phosphate, bis (1-butenyl) vinyl phosphate, methyl divinyl phosphate, ethyl divinyl phosphate, methyl bis (1-propenyl) phosphate, ethyl bis (1-propenyl) phosphate Dimethyl vinyl phosphate, dimethyl phosphate (1-propenyl), diethyl vinyl phosphate, diethyl phosphate (1-propenyl) and the like.

  Examples of the method for synthesizing the phosphate ester compound (B) in the present invention include, but are not limited to, a dehydrochlorination reaction of chloroethyl phosphate and a nucleophilic substitution reaction of various alcoholates to phosphorus oxychloride.

  The electrode protective film forming agent (A) of the present invention forms a protective film by electrolytic polymerization of alkenyl groups on the electrode surface in the lithium secondary battery during charging. By forming a protective film on the electrode surface, decomposition of the nonaqueous solvent on the electrode surface is suppressed, and charge / discharge cycle characteristics are greatly improved.

  The electrode protective film forming agent (A) of the present invention comprises an aliphatic hydrocarbon compound (D1) having a vinyloxy group or 1-propenyloxy group, or an oligoether compound (D2) having a vinyloxy group or 1-propenyloxy group. You may contain.

  The content ratio of the compound (D1) or (D2) in the electrode protective film forming agent (A) is preferably 0 to 20 based on the total weight of the electrode protective film forming agent from the viewpoint of charge / discharge cycle characteristics and high temperature storage characteristics. % By weight, more preferably 0.05 to 5% by weight.

  The aliphatic hydrocarbon (D1) having a vinyloxy group or 1-propenyloxy group or the oligoether compound (D2) having a vinyloxy group or 1-propenyloxy group functions as a positive electrode protective film forming agent. That is, the compound (D1) or (D2) forms a protective film that suppresses decomposition of the solvent at the positive electrode. This protective film suppresses the decomposition of the electrolyte solution on the electrode surface under a high voltage and improves the charge / discharge cycle characteristics.

Examples of the aliphatic hydrocarbon (D1) having a vinyloxy group or 1-propenyloxy group include linear or branched alkanes having 2 to 20 carbon atoms (ethane, propane, butane, pentane, hexane, octane, decane, dodecane, tridecane) , Tetradecane, pentadecane, octadecane, eicosane, etc.), a compound in which one or more hydrogen atoms are substituted with a vinyloxy group or a 1-propenyloxy group, a linear or branched alkene having 2 to 20 carbon atoms (ethylene, propene, butene) , Pentene, hexene, octene, decene, undecene, dodecene, tridecene, tetradecene, pentadecene, octadecene, eicosene, etc.) and one or more hydrogen atoms substituted with a vinyloxy group or 1-propenyloxy group and a carbon number of 3 20 cycloalkanes (cyclo Hexane, cyclodecane, cyclododecane, compounds substituted with one or more hydrogen atoms in a vinyloxy group or a 1-propenyloxy group cyclohexene and cyclododecene, etc.) or cycloalkenes (cyclohexene and cyclodecene) and the like.
As an oligoether compound (D2) having a vinyloxy group or a 1-propenyloxy group, a polyoxyalkylene having 1 to 10 repeating units of an oxyalkylene group (oxyethylene group, oxypropylene group, oxybutylene group, etc.) In which one or two terminal hydroxyl groups are substituted with a vinyloxy group or a 1-propenyloxy group.

  Among these, from the viewpoint of charge / discharge cycle characteristics, a linear alkane compound having 4 to 10 carbon atoms (D11) having a vinyloxy group or 1-propenyloxy group at both ends, a vinyloxy group or 1-propenyloxy group is preferable. A cyclohexane derivative (D12) having two or more and an oligoether compound (D21) having a vinyloxy group or 1-propenyloxy group at both ends, and more preferably two or more vinyloxy groups or 1-propenyloxy groups. It has a cyclohexane derivative.

As a C4-C10 linear alkyl compound (D11) which has a vinyloxy group or 1-propenyloxy group at both ends, the compound etc. which are shown by General formula (4) are mentioned.
R ⁴ —CH═CH—O— (CH ₂ ) _p —O—CH═CH—R ⁵ (4)
R ⁴ and R ⁵ in the general formula (4) are each independently a hydrogen atom or a methyl group, and p is an integer of 4 to 10.

  Specific examples of the compound represented by the general formula (4) include 1,4-butanediol divinyl ether, 1,5-pentanediol divinyl ether, 1,6-hexanediol divinyl ether, 1,7-heptanediol divinyl ether. 1,8-octanediol divinyl ether, 1,9-nonanediol divinyl ether, 1,10-decanediol divinyl ether, 1,4-butanediol (1-propenyl) vinyl ether, 1,5-pentanediol (1- Propenyl) vinyl ether, 1,6-hexanediol (1-propenyl) vinyl ether, 1,7-heptanediol (1-propenyl) vinyl ether, 1,8-octanediol (1-propenyl) vinyl ether, 1,9-nonanediol ( 1-propenyl) bi Ether, 1,10-decanediol (1-propenyl) vinyl ether, 1,4-butanediol di (1-propenyl) ether, 1,5-pentadiol di (1-propenyl) ether, 1,6-hexanediol di (1-propenyl) ether, 1,7-heptanediol di (1-propenyl) ether, 1,8-octanediol di (1-propenyl) ether, 1,9-nonanediol di (1-propenyl) ether and 1 , 10-decanediol di (1-propenyl) ether and the like. These can be obtained commercially.

Among these, from the viewpoint of charge / discharge cycle characteristics, preferred are compounds in which R ⁴ and R ⁵ are each a hydrogen atom and p is an integer of 6 to 8.

Specific examples of the cyclohexane derivative (D12) having two or more vinyloxy groups or 1-propenyloxy groups include 1,2-bis (1-propenoxymethyl) cyclohexane and 1,3-bis (1-propenoxy). Methyl) cyclohexane, 1,4-bis (1-propenoxymethyl) cyclohexane, 1,3,5-tris (1-propenoxymethyl) cyclohexane, 1,2-bis (vinyloxymethyl) cyclohexane, 1, Examples include 3-bis (vinyloxymethyl) cyclohexane, 1,4-bis (vinyloxymethyl) cyclohexane, 1,3,5-tris (vinyloxymethyl) cyclohexane, and the like. These can be obtained commercially.

Examples of the oligoether compound (D21) having a vinyloxy group or 1-propenyloxy group at both ends include compounds represented by the general formula (5).
R ⁶ —CH═CH—O— (C ₂ H ₄ O) _q —CH═CH—R ⁷ (5)
R ⁶ and R ⁷ in the general formula (5) are each independently a hydrogen atom or a methyl group, and q is an integer of 1 to 5.

  Specific examples of the compound represented by the general formula (5) include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, pentaethylene glycol divinyl ether, ethylene glycol (1-propenyl) vinyl ether. , Diethylene glycol (1-propenyl) vinyl ether, triethylene glycol (1-propenyl) vinyl ether, tetraethylene glycol (1-propenyl) vinyl ether, pentaethylene glycol (1-propenyl) vinyl ether, ethylene glycol di (1-propenyl) ether, diethylene glycol Di (1-propenyl) ether, triethylene glycol di (1-propenyl) ether Le, tetraethylene glycol di (1-propenyl) ether and pentaethylene glycol di (1-propenyl) ether and the like. These can be obtained commercially.

Among these, a compound in which R ⁶ and R ⁷ are hydrogen atoms and q is 2 or 3 is preferable from the viewpoint of charge / discharge cycle characteristics.

  The lithium secondary battery electrolyte of the present invention contains an electrode protective film forming agent (A), a nonaqueous solvent (E) and an electrolyte (F), and preferably further contains a Lewis base (C).

  Examples of the Lewis base (C) include an azacrown ether derivative (C1) and / or a triazole derivative (C2). Among these, (C1) is preferable from the viewpoint of charge / discharge cycle characteristics.

  Examples of the azacrown ether derivative (C1) include an alkenyl group (a11) represented by the general formula (2) and an alkenyl group represented by the general formula (3) on one or more nitrogen atoms in the azacrown ether ring. a12), a (meth) acryloyloxyalkyl group and a substituent (a) having at least one polymerizable unsaturated double bond selected from the group consisting of a (meth) acryloylalkyl group. It is done.

  The azacrown ether derivative (C1) has a 9- to 24-membered crown ether skeleton having 1 to 4 nitrogen atoms, and a polymerizable unsaturated double bond on one or more of the nitrogen atoms of the skeleton The thing which the substituent (a) which has is couple | bonded is preferable.

Examples of 9- to 24-membered crown ethers having 1 to 4 nitrogen atoms include aza-9-crown-3-ethers (4-aza-9-crown-3-ethers and 4,7-diaza-9s). -Crown-3-ether and the like), aza-12-crown-4-ether (such as 4-aza-12-crown-4-ether and 4,10-diaza-12-crown-4-ether), aza-14 -Crown-4-ether (such as 4-aza-14-crown-4-ether and 4,10-diaza-14-crown 4-ether), aza-15-crown-5-ether (4-aza-15- Crown-5-ether, 4,10-diaza-15-crown-5-ether, 4,14-diaza-15-crown-5 and 4,10,16-triaza-15-crown-5-ether ), Aza-18-crown-6-ether (4-aza-18-crown 6-ether, 4,10-diaza-18-crown-6-ether and 4,10,16-triaza-18-crown-6) -Ether etc.), aza-21-crown-7-ether (4-aza-21-crown-7-ether, 4,10-diaza-21-crown-7-ether and 4,10,16-triaza-21 -Crown-7-ether etc.) and aza-24-crown-8-ether (4-aza-24-crown-8-ether, 4,10-diaza-24-crown-8-ether and 4,10,16) -Triaza-24-crown-8-ether, etc.).
Of these, aza-12-crown-4-ether, aza-14-crown-4-ether, aza-15-crown-5-ether and aza- are preferred from the viewpoint of the coordination power with lithium ions. 18-crown-6-ether, more preferably 4-aza-12-crown-4-ether, 4,10-diaza-12-crown-4-ether, 4-aza-15-crown-5 Ether and 4,10-diaza-15-crown-5 ether.

  The number of nitrogen atoms in the azacrown ether skeleton is preferably 1 to 3, more preferably 1 or 2, from the viewpoint of coordination power to lithium ions.

  Examples of the substituent (a) having a polymerizable unsaturated double bond that the azacrown ether derivative (C1) has include an alkenyl group (a11) and a general formula (3) represented by the general formula (2). ) Alkenyl group (a12), (meth) acryloyloxyalkyl group, (meth) acryloylalkyl group, and the like, which are preferred, and the same are preferred.

  Specific examples of the azacrown ether derivative (C1) include N- (methyl 2-butenoate) -4-aza-12-crown-4-ether, N, N-di- (methyl 2-butenoate) -4. , 10-diaza-12-crown-4-ether, N- (methyl 2-butenoate) -4-aza-15-crown-5-ether, N, N-di- (methyl 2-butenoate) -4 , 10-diaza-15-crown-5-ether, N- (cinnamyl) -4-aza-12-crown-4-ether, N, N-di- (cinnamyl) -4,10-diaza-12-crown -4-ether, N- (cinnamyl) -4-aza-15-crown-5-ether, N, N-di- (cinnamyl) -4,10-diaza-15-crown-5-ether, N- ( 4-vinylbenzyl) -4-aza- 2-crown-4-ether, N, N-di- (4-vinylbenzyl) -4,10-diaza-12-crown-4-ether, N- (4-vinylbenzyl) -4-aza-15- Crown-5-ether, N, N-di- (4-vinylbenzyl) -4,10-diaza-15-crown-5-ether, N, N-di- (1-acryloyloxyethyl) -4,10 -Diaza-15-crown-5-ether, N- (1-acryloyloxyethyl) -4-aza-14-crown-4-ether, N- (ethyl 2-pentenoate) -4-aza-18-crown -6-ether and N, N-di- (methyl 2-pentenoate) -4,14-diaza-18-crown-6-ether.

  The azacrown ether derivative (C1) in the present invention can be produced by a usual method or the like. For example, a method of reacting an unsubstituted azacrown ether with an alkyl halide having a polymerizable unsaturated double bond in an organic solvent in the absence of a catalyst or in the presence of a catalyst.

  Examples of the halogenated alkyl having a polymerizable unsaturated double bond include 4-bromo-2-butenoic acid methyl ester, 4-chloro-2-butenoic acid methyl ester, 1-bromo-4-cyano-2-butene, 1 -Chloro-4-cyano-2-butene, acrylic acid chloromethyl ester, acrylic acid bromomethyl ester, acrylic acid-2-chloroethyl ester, acrylic acid-2-bromoethyl ester, methacrylic acid chloromethyl ester, bromomethacrylic acid bromo Examples include methyl ester, methacrylic acid-2-chloroethyl ester, methacrylic acid-2-bromoethyl ester, cinnamilk chloride, cinnamyl bromide, 4- (chloromethyl) styrene, and 4- (bromomethyl) styrene.

  Examples of the triazole derivative (C2) include 1,2,3-benzotriazole, 5-methyl-1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1,2,4. -Triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5 -Ethyl-1,2,4-triazole, 3-amino-5-propyl-1,2,4-triazole, 3-amino-5-butyl-1,2,4-triazole and the like. These can be obtained commercially. Of these, 3-amino-1,2,4-triazole is preferable from the viewpoint of charge / discharge cycle characteristics.

  As non-aqueous solvent (E), what is used for the electrolyte solution of normal lithium secondary battery can be used, for example, cyclic or chain carbonate ester, chain carboxylate ester, cyclic or chain ether, phosphoric acid Esters, lactone compounds, nitrile compounds, amide compounds and the like and mixtures thereof can be used. Examples of the cyclic carbonate include propylene carbonate, ethylene carbonate and butylene carbonate. Examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate.

Examples of chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, and methyl propionate.
Examples of the cyclic ether include tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1,4-dioxane and the like.
Examples of the chain ether include dimethoxymethane and 1,2-dimethoxyethane.
Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate, tripropyl phosphate, tributyl phosphate, tri (trifluoromethyl) phosphate, tri (trichloromethyl) phosphate, Tri (trifluoroethyl) phosphate, tri (triperfluoroethyl) phosphate, 2-ethoxy-1,3,2-dioxaphospholan-2-one, 2-trifluoroethoxy-1,3,2- Examples include dioxaphospholan-2-one and 2-methoxyethoxy-1,3,2-dioxaphosphoran-2-one.
Examples of the lactone compound include γ-butyrolactone and γ-valerolactone. A nitrile compound includes acetonitrile.
Examples of the amide compound include dimethylformamide.
Of the non-aqueous solvents, from the viewpoint of battery output and charge / discharge recycling characteristics, preferred are cyclic carbonates, chain carbonates and phosphates, and more preferred are cyclic carbonates.

The electrolyte (F), can be used those used in conventional lithium secondary battery electrolyte, a lithium salt of an inorganic acid _{[LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6 , and LiClO _4, etc.]; an organic acid Lithium salts [LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) _2, LiC (CF ₃ SO ₂ ) _3, etc.]. Among these, LiPF ₆ is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

  The electrode protective film forming agent of the present invention is added to an electrolytic solution to form a battery, and then charged to form a protective film by electrolytic polymerization of double bonds.

  The preferred contents or concentrations of the electrode protective film forming agent (A), Lewis base (C), non-aqueous solvent (E) and electrolyte (F) in the electrolytic solution of the present invention are as follows.

The content of (A) is preferably based on the total weight of the electrode protective film forming agent (A), the non-aqueous solvent (E) and the electrolyte (F) from the viewpoints of charge / discharge cycle characteristics, battery capacity, and high-temperature storage characteristics. Is 0.01 to 10% by weight, more preferably 0.05 to 1% by weight.
The content of (C) is preferably 0 to 10% by weight, more preferably 0.01 to 10% by weight, particularly preferably from the viewpoint of battery capacity, battery output, and charge / discharge cycle characteristics. Is 0.05 to 1% by weight.
The content of (E) is preferably 70 to 99 from the viewpoint of battery output and charge / discharge cycle characteristics, based on the total weight of the electrode protective film forming agent (A), the nonaqueous solvent (E) and the electrolyte (F). % By weight, more preferably 93 to 99% by weight.
The content of (F) is preferably 0.3 to 25% by weight based on the total weight of the electrode protective film forming agent (A), the nonaqueous solvent (E) and the electrolyte (F) from the viewpoint of battery output. More preferably, it is 0.5 to 20% by weight.
The concentration of (F) is preferably 0.01 to 3 mol / L, more preferably 0.05 to 1.5 mol / L from the viewpoint of battery output and charge / discharge cycle characteristics, based on the capacity of the electrolytic solution. is there.

  The method for preparing the electrolytic solution of the present invention is not particularly limited, and can be prepared by dissolving the electrolyte, the electrode protective film forming agent (A) of the present invention, and other additives in a non-aqueous solvent. Moreover, it is preferable to dehydrate each raw material in advance when preparing the electrolytic solution so that the amount of water in the electrolytic solution is 50 ppm or less.

The electrolytic solution of the present invention is useful as an electrolytic solution for a lithium secondary battery or a lithium ion capacitor.
A lithium secondary battery using the electrolytic solution of the present invention is obtained by injecting the electrolytic solution of the present invention into a battery can containing a positive electrode, a negative electrode, and a separator and sealing the battery can.

  As a positive electrode in a lithium secondary battery, a positive electrode active material, a conductive agent and a binder dispersed in a solvent and slurried are applied to a positive electrode current collector with a coating device such as a bar coater and dried. Then, the solvent can be removed and, if necessary, a product pressed with a press machine can be used.

Examples of the positive electrode active material include composite oxides of lithium and transition metals (such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ and LiMn ₂ O ₄ ), transition metal oxides (such as MnO ₂ and V ₂ O ₅ ), and transition metal sulfides. Products (such as MoS ₂ and TiS ₂ ), and conductive polymers (such as polyaniline, polyvinylidene fluoride, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polycarbazole).

  Conductive agents include graphite (natural graphite, artificial graphite, etc.), carbon blacks (carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), metal powder (aluminum powder and nickel) Powder) and conductive metal oxides (such as zinc oxide and titanium oxide).

  Examples of the binder include polymer compounds such as starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene.

Examples of the solvent include 1-methyl-2-pyrrolidone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine, and tetrahydrofuran.
Examples of the current collector for positive electrode include aluminum, titanium, stainless steel, nickel, baked carbon, conductive polymer, conductive glass, and the like.

In the lithium secondary battery, preferred contents of the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode are as follows.
The content of the positive electrode active material is preferably 70 to 98% by weight, more preferably 90 to 98% by weight. The content of the conductive agent is preferably 1 to 29% by weight, more preferably 1 to 10% by weight. The content of the binder is preferably 1 to 29% by weight, more preferably 1 to 10% by weight.

  The amount of the solvent used in the slurry of the positive electrode active material, conductive agent and binder is preferably 20 to 70% by weight, more preferably based on the total weight of the positive electrode active material, conductive agent and binder. 30 to 60% by weight.

  As a negative electrode in a lithium secondary battery, a negative electrode active material, a conductive agent and a binder dispersed in a solvent are applied to a negative electrode current collector with a coating device such as a bar coater and dried. What removed the solvent and pressed with the press if necessary can be used.

Examples of negative electrode active materials include graphite, polymer compound fired bodies (for example, those obtained by firing and carbonizing phenol resin and furan resin, etc.), cokes (pitch coke, needle coke, petroleum coke, etc.), carbon fiber, and high conductivity. Examples thereof include molecules (polyacetylene, polypyrrole, etc.), metal alloys (lithium-aluminum alloy, lithium-aluminum-manganese alloy, etc.) and the like.
As the conductive agent, the binder and the solvent, the same materials as those used for the production of the positive electrode can be used.
Examples of the current collector for the negative electrode include copper, stainless steel, nickel, aluminum, titanium, calcined carbon, conductive polymer, conductive glass, and an aluminum-cadmium alloy.

  In the lithium secondary battery, the preferable content of each of the negative electrode active material, the conductive agent, and the binder based on the total weight of the negative electrode is preferable for each of the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode. It is the same as the content.

  The amount of solvent used in slurrying the negative electrode active material, conductive agent and binder is the same as the amount of solvent used in slurrying the positive electrode active material, conductive agent and binder.

  As separators in lithium secondary batteries, polyethylene, polypropylene film microporous membrane, porous polyethylene film and multilayer film of polypropylene, polyester fiber, aramid fiber, glass fiber, etc., and silica on the surface thereof , Alumina, titania and other ceramic fine particles attached thereto.

  As the battery can in the lithium secondary battery, metal materials such as stainless steel, iron, aluminum, and nickel-plated steel can be used, but plastic materials can also be used depending on the battery application. The battery can can be formed into a cylindrical shape, a coin shape, a square shape, or any other shape depending on the application.

The electrolytic solution of the present invention is also useful as an electrolytic solution for a lithium ion capacitor.
A lithium ion capacitor using the electrolytic solution of the present invention can be obtained by injecting the electrolytic solution of the present invention into a capacitor can containing a positive electrode, a negative electrode and a separator and sealing the capacitor can.

  As a positive electrode in a lithium ion capacitor, activated carbon, a conductive agent and a binder dispersed in a solvent are slurried, applied to a positive electrode current collector with a coating device such as a bar coater, and dried to obtain a solvent. What was removed and pressed with a press if necessary can be used.

  Conductive agents include graphite (natural graphite, artificial graphite, etc.), carbon blacks (carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), metal powder (aluminum powder and nickel) Powder) and the like, and conductive metal oxides (such as zinc oxide and titanium oxide).

  Examples of the binder include polymer compounds such as starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene.

Examples of the solvent include 1-methyl-2-pyrrolidone, methyl ethyl ketone, dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine, and tetrahydrofuran.
Examples of the current collector for positive electrode include aluminum, titanium, stainless steel, nickel, baked carbon, conductive polymer, conductive glass, and the like.

In the lithium ion capacitor, preferable contents of the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode are as follows.
The content of the positive electrode active material is preferably 70 to 98% by weight, more preferably 90 to 98% by weight. The content of the conductive agent is preferably 1 to 29% by weight, more preferably 1 to 10% by weight. The content of the binder is preferably 1 to 29% by weight, more preferably 1 to 10% by weight.

  The amount of the solvent used in the slurry of the positive electrode active material, conductive agent and binder is preferably 20 to 70% by weight, more preferably based on the total weight of the positive electrode active material, conductive agent and binder. 30 to 60% by weight.

  As a negative electrode in a lithium ion capacitor, a negative electrode active material, a conductive agent and a binder dispersed in a solvent are slurried, applied to a negative electrode current collector with a coating device such as a bar coater, and dried to obtain a solvent. Can be used if necessary.

Examples of the negative electrode active material in the present invention include amorphous carbon, graphite, tin and alloys thereof, and silicon and alloys thereof.
As the conductive agent, the binder and the solvent, the same materials as those used for the production of the positive electrode can be used.
Examples of the current collector for the negative electrode include copper, stainless steel, nickel, aluminum, titanium, calcined carbon, conductive polymer, conductive glass, and an aluminum-cadmium alloy.

  In the lithium ion capacitor, the preferable content of each of the negative electrode active material, the conductive agent, and the binder based on the total weight of the negative electrode is the preferable content of each of the positive electrode active material, the conductive agent, and the binder based on the total weight of the positive electrode. The amount is the same.

  The amount of solvent used in slurrying the negative electrode active material, conductive agent and binder is the same as the amount of solvent used in slurrying the positive electrode active material, conductive agent and binder.

  As a separator in a lithium ion capacitor, polyethylene, a microporous film of a polypropylene film, a multilayer film of a porous polyethylene film and polypropylene, a non-woven fabric made of polyester fiber, aramid fiber, glass fiber, etc., and silica on the surface thereof, Examples include those to which ceramic fine particles such as alumina and titania are attached.

  As the battery can in the lithium ion capacitor, metal materials such as stainless steel, iron, aluminum, and nickel-plated steel can be used, but plastic materials can also be used depending on the battery application. The battery can can be formed into a cylindrical shape, a coin shape, a square shape, or any other shape depending on the application.

  The electrode protective film forming agent (A) in the present invention can be used by adding to both the positive electrode and the negative electrode, but is preferably added to the positive electrode.

As a method for adding to the positive electrode, an electrode protective film forming agent (A) is added to a slurry obtained by dispersing a positive electrode active material, a conductive agent and a binder in a solvent, and a bar coater or the like is added to the positive electrode current collector. And a method of removing the solvent by drying, and pressing with a press if necessary.

  As a method for adding to the negative electrode, an electrode protective film forming agent (A) is added to a slurry obtained by dispersing a negative electrode active material, a conductive agent and a binder in a solvent, and a bar coater or the like is added to the negative electrode current collector. And a method of removing the solvent by drying, and pressing with a press if necessary.

The addition amount of the electrode protective film forming agent (A) when added to the positive electrode is preferably 0.1 to 10% by weight, more preferably based on the positive electrode active material from the viewpoints of charge / discharge cycle characteristics, battery capacity and high storage characteristics. Is 0.5 to 5% by weight.
The amount of the electrode protective film-forming agent (A) added to the negative electrode is preferably 0.1 to 10% by weight, more preferably based on the negative electrode active material from the viewpoints of charge / discharge cycle characteristics, battery capacity and high storage characteristics. Is 0.5 to 5% by weight.

  Hereinafter, although an example and a manufacture example explain the present invention further, the present invention is not limited to these. In the following, “%” means “% by weight” and “parts” means “parts by weight”.

<Example 1>: Trivinyl phosphate (B-1)
In a flask equipped with a stirrer, a thermometer and a condenser tube, 10.0 parts of tris phosphate (2-chloroethyl [manufactured by Aldrich Co., Ltd.]) and 40.0 parts of tert-butanol were charged and dissolved uniformly with stirring. Thereafter, 15.7 parts of potassium tert-butoxide was added in four portions at room temperature with stirring, and the resulting mixture was stirred at 90 ° C. for 1 hour, cooled to room temperature, dissolved in diethyl ether and filtered through Celite. The solvent was distilled off from the obtained filtrate to obtain 4.18 parts of the target trivinyl phosphate (B-1) (yield 67.7%).

<Example 2>: Tris (1-propenyl) phosphate (B-2)
In a flask equipped with a stirrer, a thermometer and a condenser tube, 10.0 parts of phosphorus oxychloride [manufactured by Wako Pure Chemical Industries, Ltd.], 12.2 parts of propionaldehyde, and tetrahydrofuran (hereinafter abbreviated as THF) 40.0 The parts were charged and dissolved uniformly with stirring. To the obtained solution, 21.7 parts of lithium diisopropylamide (dispersed in hexane at 10% by weight; hereinafter abbreviated as LDA) was added at −78 ° C. with stirring, and then stirred at the same temperature for 1 hour. did. After raising the temperature to room temperature over 1 hour, 10.0 parts of 0.1 N dilute hydrochloric acid and 40.0 parts of ethyl acetate were added, and the aqueous layer was separated. After distilling off the solvent, the resulting mixture was purified with an alumina column [150 mesh, Blockman 1, standard grade, manufactured by Aldrich Co., Ltd.] using ethyl acetate as a solvent to obtain the target tris (1-propenyl) phosphate ( B-2) 9.69 parts were obtained (yield 52.1%).

<Example 3>: Tris (1-butenyl) phosphate (B-3)
In Example 2, the same operation as in Production Example 2 was carried out except that 12.2 parts of propionaldehyde was changed to 15.1 parts of butyraldehyde, and tris (1-butenyl) phosphate (B-3) 7.42 was obtained. Part (yield 57.0%).

<Example 4>: Methyldivinyl phosphate (B-4)
Into a flask equipped with a stirrer, thermometer and condenser, was charged 10.0 parts of phosphorus oxychloride [manufactured by Wako Pure Chemical Industries, Ltd.], 5.76 parts of acetaldehyde, and 40.0 parts of THF. Dissolved. To the obtained solution, 21.7 parts of LDA was added at −78 ° C. with stirring, followed by stirring at the same temperature for 30 minutes, and then 3.14 parts of methanol was added. After raising the temperature to room temperature over 1 hour, 10.0 parts of 0.1 N dilute hydrochloric acid and 40.0 parts of ethyl acetate were added, and the aqueous layer was separated. After distilling off the solvent, the resulting mixture was purified with an alumina column [150 mesh, Blockman 1, standard grade, manufactured by Aldrich Co., Ltd.] using ethyl acetate as a solvent to obtain the desired methyl divinyl phosphate (B-4). 5.26 parts were obtained (yield 49.1%).

<Example 5>: Dimethyl vinyl phosphate (B-5)
The same operation as in Example 4 was performed except that acetaldehyde was changed to 2.88 parts and methanol was changed to 5.23 parts in Example 4, and the target methyldivinyl phosphate (B-5) 4.98 was obtained. Part (yield 50.1%).

<Example 6>: Diethyl phosphate (1-propenyl) (B-6)
In Production Example 4, the same experimental operation as in Production Example 5 was carried out except that acetaldehyde and methanol were changed to propionaldehyde and ethanol, respectively, and 6.56 parts of diethyl phosphate (1-propenyl) (B-6) was added. Obtained (yield 51.7%).

<Production Example 1>
In a flask equipped with a stirrer, a thermometer and a condenser, 4,10-diaza-15-crown-5-ether [Tokyo Chemical Industry Co., Ltd.] 0.61 part, 4-bromo-2-butenoic acid methyl ester [Tokyo Chemical Industry Co., Ltd.] 1 part and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. After the acetonitrile was distilled off, the reaction product was purified by an alumina column [150 mesh, Blockman 1, standard grade, manufactured by Aldrich Co., Ltd.] using acetone as a solvent, and N, N-di- (2-butenoate methyl) -4, 0.85 part of 10-diaza-15-crown-5-ether (C1-1) was obtained (yield 71%).

<Examples 7 to 16 and Comparative Examples 1 to 4>
[Preparation of electrolyte]
In accordance with the blending examples in Table 1, compounds (B), (C) and (E) were blended, and LiPF ₆ was dissolved as an electrolyte (F) so as to have a concentration of 1.0 mol / L. To 16 and Comparative Examples 1 to 4 were prepared.

In addition, the symbol of compound (B), (D), (B ') and (C) in Table 1 is as follows.
(B-1): Trivinyl phosphate (B-2): Tris phosphate (1-propenyl)
(B-3): Tris phosphate (1-butenyl)
(B-4): methyldivinyl phosphate (B-5): dimethylvinyl phosphate (B-6): diethyl phosphate (1-propenyl)
(D1-1): 1,4-butanediol divinyl ether (D1-2): 1,4-bis (vinyloxymethyl) cyclohexane (B′-1): trimethyl phosphate (B′-2): phosphoric acid Trioctyl (C1-1): N, N-di- (2-butenoic acid methyl) -4,10-diaza-15-crown-5-ether (C2-1): 3-amino-1,2,4- Triazole

  Trimethyl phosphate (B′-1) described in Table 1 [manufactured by Tokyo Chemical Industry Co., Ltd.], trioctyl phosphate (B′-2) [manufactured by Wako Pure Chemical Industries, Ltd.], 1,4-butanediol Divinyl ether (D1-1) [manufactured by Nippon Carbide Industries Co., Ltd.], 1,4-bis (vinyloxymethyl) cyclohexane (D1-2) [manufactured by Nippon Carbide Industries Co., Ltd.], and 3-amino-1, Commercially available products were used for 2,4-triazole (C2-1) [manufactured by Tokyo Chemical Industry Co., Ltd.].

(1) Production of Secondary Battery Cell (1-1) Production of Positive Electrode 9.0 parts of LiCoO ₂ powder, 0.5 part of Ketjen Black [manufactured by Aldrich] and polyvinylidene fluoride [manufactured by Aldrich] 0.5 After thoroughly mixing parts with a mortar, 7.0 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] was added, and further mixed well with a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the atmosphere, dried at 100 ° C. for 15 minutes, and further under reduced pressure (10 mmHg) at 80 ° C. for 5 minutes. It dried and produced the positive electrode with a film thickness of 30 micrometers.

(1-2) Production of Negative Electrode 92.5 parts of graphite powder having an average particle size of about 8 to 12 μm, 7.5 parts of polyvinylidene fluoride and 200 parts of N-methylpyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] are sufficient in a mortar. To obtain a slurry. The obtained slurry was applied to one side of a 20 μm thick copper foil, dried at 100 ° C. for 15 minutes to evaporate the solvent, punched out to 12 mmφ, and made a negative electrode with a thickness of 30 μm using a press.

(1-3) Production of secondary battery cell The positive battery and the negative electrode obtained as described above are arranged at both ends in the 2032 type coin cell so that the respective coated surfaces face each other. Produced.

(2) Production of Lithium Ion Capacitor (2-1) Production of Positive Electrode As a positive electrode active material, activated carbon having a specific surface area obtained by an alkali activation method of about 2200 m 2 / g was used. Activated carbon powder, acetylene black, and polyvinylidene fluoride are mixed in a weight ratio of 80:10:10, and the mixture is added to N-methylpyrrolidone as a solvent. Obtained. This slurry was applied onto an aluminum foil having a thickness of 30 μm by a doctor blade method, temporarily dried, and then cut so that the electrode size was 20 mm × 30 mm. The electrode thickness was about 50 μm. Before assembling the cell, it was dried in a vacuum at 120 ° C. for 10 hours to produce a positive electrode for a lithium ion capacitor.

(2-2) Production of negative electrode 80 parts of graphite powder having an average particle diameter of about 8 to 12 μm, 10 parts of acetylene black, and 10 parts of polyvinylidene fluoride were mixed, and this mixture was added to N-methylpyrrolidone as a solvent. The mixture was stirred to obtain a slurry. This slurry was applied onto a copper foil having a thickness of 18 μm by a doctor blade method and temporarily dried, and then cut so that the electrode size was 20 mm × 30 mm. The electrode thickness was about 50 μm. Before assembling the cell, it was dried in vacuum at 120 ° C. for 5 hours to produce a negative electrode for a lithium ion capacitor.

(2-3) Doping of lithium to the negative electrode The negative electrode obtained as described above was doped with lithium as follows. The negative electrode and lithium metal foil were sandwiched between separators (polypropylene nonwoven fabric) and set in a beaker cell, and a predetermined amount of lithium ions was occluded in the negative electrode over about 10 hours. The doping amount of lithium was about 75% of the negative electrode theoretical capacity.

(2-4) Assembly of Capacitor Cell A separator (polypropylene nonwoven fabric) is inserted between the positive electrode and the negative electrode obtained as described above, impregnated with an electrolytic solution, and stored in an aluminum laminate film of polypropylene. A lithium ion capacitor was produced by sealing in a case.
[Evaluation of electrolyte]
The electrolyte solutions prepared in Examples 7 to 16 and Comparative Examples 1 to 4 were sealed after the injection of the cells for the secondary battery, respectively, and the results of evaluating the high voltage charge / discharge cycle characteristics and the high temperature storage characteristics by the following methods, Table 2 shows the results of sealing after filling the capacitor cell and evaluating the high voltage charge / discharge cycle characteristics and the high temperature storage characteristics by the following methods.

<Evaluation of high voltage charge / discharge cycle characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], the battery voltage is charged at 0.1 C current to a voltage of 4.5 V, and after 10 minutes of rest, the battery voltage at 0.1 C current Was discharged to 3.5 V, and this charge / discharge was repeated. At this time, the battery capacity at the first charge and the battery capacity at the 50th cycle charge are measured, and charge / discharge cycle characteristics are calculated from the following formula. It shows that charging / discharging cycling characteristics are so favorable that a numerical value is large.
High voltage charge / discharge cycle characteristics (%) = (battery capacity at the 50th cycle charge / battery capacity at the first charge) × 100

<Evaluation of high-temperature storage characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470 type” [manufactured by Toyo Technica Co., Ltd.], charge to a voltage of 4.5 V with a current of 0.1 C, and after a pause of 10 minutes, a voltage of 3 with a current of 0.1 C Discharge to 5V and measure capacity (initial battery capacity). Further, the battery is charged to a voltage of 4.5 V with a current of 0.1 C, stored for 7 days at 85 ° C., then discharged to 3.5 V with a current of 0.1 C, and the battery capacity is measured (battery capacity after high-temperature storage). The high temperature storage characteristics are calculated from the following formula. It shows that a high-temperature storage characteristic is so favorable that a numerical value is large.
High temperature storage characteristics (%) = (battery capacity after high temperature storage / initial battery capacity) × 100

  The lithium secondary battery and the lithium ion capacitor containing the electrolyte solutions of Examples 7 to 16 containing the electrode protective film forming agent of Examples 1 to 6 are the lithium secondary battery and lithium containing the electrolyte solutions of Comparative Examples 1 to 4 Cycle characteristics and high-temperature storage stability are better than ion capacitors.

  Since the electrolytic solution using the electrode protective film forming agent (A) of the present invention has excellent cycle characteristics under high voltage and high-temperature storage stability, it is particularly an electrolytic solution for lithium secondary batteries or an electrolytic solution for lithium ion capacitors. It is useful as an electric vehicle.

Claims (7)

The electrode protective film forming agent (A) containing the phosphate ester compound (B) represented by the following general formula (1).

[Wherein, T ^{1 to} T ³ are each independently an alkenyl group represented by the following general formula (2), an alkenyl group represented by the following general formula (3), a saturated hydrocarbon group having 1 to 12 carbon atoms, Or an aromatic group having 6 to 12 carbon atoms, and at least one of T ^{1 to} T ³ is a substituent represented by the following general formula (2) or a substituent represented by the following general formula (3). is there. ]

[Wherein R ² is a direct bond or an alkylene group having 1 to 3 carbon atoms, and Q ¹ , Q ² and Q ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or a carbon number. It is a 1 or 2 fluoroalkyl group, a phenyl group, a cyano group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, or an alkoxycarbonyl group having 1 to 4 carbon atoms. ]

[Wherein R ³ is an alkylene group having 1 to ³ carbon atoms, Q ⁴ is a hydrogen atom or a halogen atom, and Q ⁵ , Q ⁶ and Q ⁷ are each independently a hydrogen atom, a halogen atom or a carbon number. An alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 or 2 carbon atoms, a phenyl group, a cyano group, a carboxyl group, an alkoxy group having 1 to 3 carbon atoms, or an alkoxycarbonyl group having 1 to 4 carbon atoms. ] The electrode protective film forming agent (A) according to claim 1, wherein the alkenyl group represented by the general formula (2) is a vinyl group or a 1-propenyl group.   The electrolyte solution containing the electrode protective film formation agent (A) of Claim 1 or 2. The electrolyte solution according to claim 3, which is for a lithium secondary battery or a lithium ion capacitor. The lithium secondary battery or lithium ion capacitor which has the electrolyte solution of Claim 3. The lithium secondary battery or lithium ion capacitor which has an electrode active material coat | covered with the electrode protective film formation agent (A) of Claim 1 or 2. The lithium secondary battery or lithium ion capacitor which contains the electrode protective film formation agent (A) of Claim 1 or 2 in a positive electrode and / or a negative electrode.