JP2001052965A - Non-aqueous electrolyte solution for capacitor, electrode, and capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a voltage resistance and charging/discharging cycle characteristics by allowing a non-aqueous electrolyte solution for a capacitor to comprise an electrolyte and an electrolyte solvent which comprises a compound comprising a specific Si-contained radical, for less generation of gas. SOLUTION: A non-aqueous electrolyte solution for a capacitor comprises a compound which comprises an Si-contained radical shown with an equation as an electrolyte solvent. R1, R2, and R3 are a monovalent radical selected out of hydrogen atom, halogen atom, hydrocarbon radical of carbon number 1-6 such as alkyl group, and oxy-hydrocarbon radical of carbon number 1-6 such as alcoxyl. The hydrocarbon part of the hydrocarbon radical or oxy- hydrocarbon radical may be either in chain or cyclic like phenyl radical, or may be saturated or non-saturated, with a part of hydrogen atom of the hydrocarbon part allowed to be substituted with halogen atom, As the electrolyte of non-aqueous electrolyte solution, ammonium salt, phosphonium salt, or others may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte for a capacitor containing a Si compound, an electrode, and a capacitor using the same. The present invention relates to a nonaqueous electrolytic solution for a capacitor, an electrode for a capacitor, and a capacitor using the same. This non-aqueous electrolyte is particularly suitable for electric double layer capacitors.

[0002]

2. Description of the Related Art An electric double layer capacitor is a small power DC power source having an intermediate capacity between a battery and a capacitor.
It is widely used as a backup power source for C and memory, and as an auxiliary or substitute for a secondary battery. In recent years, camera-integrated VT
It is conceivable to use the electric double-layer capacitor in newly emerging portable electronic devices such as mobile phones, laptop computers and the like, and for this purpose, it is required to increase the energy density of the electric double-layer capacitor.

[0003] This electric double layer capacitor does not convert a chemical change into electric energy like a storage battery, but utilizes a large capacity of the electric double layer generated at an interface between an electrode and an electrolytic solution to charge the electric charge of the double layer. Is used as a power source by taking in and out in the same manner as charging and discharging of a battery.

[0004] Such an electric double layer capacitor is composed of two electrodes, a separator and a generally corrosion-resistant electrolyte. That is, two electrodes formed from a material having a large surface area such as activated carbon and a binder such as a fluororesin are arranged so as to face each other with a porous separator interposed therebetween, and between the electrode and the porous separator. And the inside of the porous separator is filled with an electrolytic solution.

As the electrolyte, an aqueous electrolyte and an organic solvent (non-aqueous electrolyte) are used.
The aqueous electrolyte solution has a low withstand voltage of about 1.2 V and is not suitable for an electric double layer capacitor requiring a high energy density. In contrast, organic solvent-based electrolytes (non-aqueous electrolytes)
Has a higher withstand voltage than an aqueous electrolyte solution, and thus may be capable of producing a capacitor with a high energy density.

Conventionally, non-aqueous electrolytes have generally been produced by mixing and dissolving an electrolyte such as a tetrafluoroborate compound and a 4-ethylammonium compound in a non-aqueous solvent such as a cyclic carbonate having a high dielectric constant. However, it is said that the decarbonation decomposition reaction occurs at a high temperature in the cyclic carbonate ester solvent and a large amount of gas is generated with the reaction, thereby shortening the life of the capacitor. In addition, the withstand voltage of the electrolytic solution is not always sufficient, and further improvement in charge / discharge cycle characteristics is required.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a non-aqueous electrolytic solution for a capacitor, which generates less gas from an electrolyte solvent, has excellent withstand voltage and charge / discharge cycle characteristics, and is excellent in safety. The purpose of the present invention is to provide a capacitor electrode and a capacitor using the same.

[0008]

That is, the present invention provides a non-aqueous electrolyte for a capacitor comprising an electrolyte and an electrolyte solvent containing a compound having a Si-containing group represented by the formula (1):
In particular, it relates to a non-aqueous electrolyte for an electric double layer capacitor.

Embedded image

Here, R ¹ , R ² and R ³ are selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms and an oxyhydrocarbon group having 1 to 6 carbon atoms. A hydrocarbon group of the hydrocarbon group or the oxyhydrocarbon group may be linear or cyclic, and the hydrocarbon moiety may be saturated or unsaturated. In addition, some of the hydrogen atoms in the hydrocarbon portion may be replaced with halogen atoms. R ¹ , R ² and R
³ may be the same or different from each other.

The compound having a Si-containing group represented by the above formula (1) is preferably a compound represented by the following formula (2).

Embedded image Here, X is any group selected from the group consisting of an oxazolidinone group, an imidazole group, a phosphate group, a phenyl group, an alkoxy group, a halogen atom, an unsaturated alkyl group, a carbamate group, and a carbonate group, as described below. is there.

Among these compounds, in particular, N-trialkylsilyl imidazole, tris (trialkylsilyl) phosphate, 4-trialkylsilylmethyl-
1,3-dioxolan-2-one, trialkylchlorosilane, trifluoroalkyltrialkylsilane, allyltrialkylsilane, diallyldialkylsilane,
Triallylalkylsilane, acetyltrialkylsilane, alkyl-N-trialkylsilylcarbamate,
Alkyl-N, N-bistrialkylsilyl carbamates, alkyltrialkylsilyl carbonates, and 3-trialkylsilyl-2-oxazolidinones are preferred as electrolyte solvents.

The compound containing the Si-containing group is preferably used in the form of a mixed solvent with another solvent, for example, a cyclic carbonate or a phosphoric ester, and 0.01 to 50% by weight in the mixed solvent. Is desirably added to account for

The present invention also relates to a capacitor containing the above non-aqueous electrolyte, and more particularly to an electric double layer capacitor. Further, the present invention relates to a capacitor electrode in which the electrode is pretreated with the above non-aqueous electrolyte, and a capacitor incorporating such an electrode.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Next, the non-aqueous electrolyte according to the present invention,
Each configuration of the electrode and the capacitor using the same will be specifically described. Here, the non-aqueous electrolyte comprises an electrolyte and an electrolyte solvent, and is suitable as an electrolyte for a capacitor, particularly an electric double layer capacitor.

Si Compound The non-aqueous electrolyte according to the present invention contains a compound having a Si-containing group represented by the following formula (1) as an electrolyte solvent.

Embedded image

Here, R ¹ , R ² and R ³ represent a hydrogen atom, a halogen atom, a hydrocarbon group such as an alkyl group having 1 to 6 carbon atoms, and an oxy group such as an alkoxy group having 1 to 6 carbon atoms. A monovalent group selected from the group consisting of hydrocarbon groups, wherein the hydrocarbon portion of the hydrocarbon group or the oxyhydrocarbon group may be linear such as a chain or a phenyl group; It may be saturated or unsaturated, and a part of hydrogen atoms in the hydrocarbon portion may be substituted with a halogen atom.

R ¹ , R ² and R ³ are preferably a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. In addition, part or all of the hydrogen atoms of the alkyl group is a halogen atom,
In particular, it may be a group substituted by a fluorine atom. These groups may be the same or different from each other,
It is preferable that both are the same.

Examples of such groups include trimethylsilyl, triethylsilyl, tripropylsilyl, trifluoromethylsilyl, trimethoxysilyl and the like.

The Si compound having a Si-containing group represented by the formula (1) is preferably a compound represented by the following general formula (2).

Embedded image Here, X is arbitrarily selected from the following formulas (3) to (14) to form compounds (a) to (l).

(A) Oxazolidinone compound

Embedded image In the formula (3), some of the hydrogen atoms may be substituted with a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, or a halogen atom. In the hydrocarbon group, part or all of the hydrogen atoms may be substituted with halogen atoms.

As a specific example of a compound having this group, 3
-Trimethylsilyl-2-oxazolidinone, 3-trimethylsilyl-4-trifluoromethyl-2-oxazolidinone, 3-triethylsilyl-2-oxazolidinone and the like.

(B) Imidazole compound

Embedded image In the formula (4), some of the hydrogen atoms may be substituted with a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, or a halogen atom.

Specific examples of the compound having this group include N
-Trimethylsilylimidazole, N-trimethylsilyl-4-methyl-imidazole, N-triethylsilylimidazole and the like.

(C) Phosphate compound

Embedded image In the formula (5), A ¹ and A ² are a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms or a Si-containing group represented by the above formula (1), and are the same as each other; May also be different.

Specific examples of the compound having this group include tris (trimethylsilyl) phosphate, tris (triethylsilyl) phosphate, trimethylsilyldimethylphosphate, trimethylsilyldiallylphosphate and the like.

(D) cyclic carbonate compound

Embedded image In the formula (6), a part of the hydrogen atoms bonded to the carbon atoms constituting the ring is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, a halogen atom. Alternatively, Si represented by the above formula (1)
And n may be 0, 1, or 2
It is.

As a specific example of a compound having this group, 4
-Trimethylsilyl-1,3-dioxolan-2-one, 4-trimethylsilyl-5-vinyl-1,3-dioxolan-2-one, 4-trimethylsilylmethyl-
1,3-dioxolan-2-one and the like.

(E) Phenyl compound (1)

Embedded image In the formula (7), a part of the hydrogen atoms bonded to the carbon atoms constituting the benzene ring is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group,
It may be substituted with a nitro group, a halogen atom or a Si-containing group represented by the above formula (1).

Specific examples of the compound having this group include phenyltrimethylsilane, phenyltriethylsilane,
Phenyltrimethoxysilane and the like.

(F) Phenyl compound (2)

Embedded image In the formula (8), B represents —NH—, —N (CH ₃ )
—, —CH ₂ —, —CO—, —S—, —SO ₂ —, a divalent group selected from the group consisting of: and a hydrogen atom bonded to a carbon atom constituting a benzene ring. A part thereof is substituted by a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, a halogen atom or a Si-containing group represented by the above formula (1). You may.

Specific examples of the compound having this group include phenylthiotrimethylsilane, phenylthiotriethylsilane and the like.

(G) Ether compound (1) —OA ³ ... (9) In the formula (9), A ³ is a monovalent saturated or unsaturated having 1 to 6 carbon atoms. Or the Si-containing group represented by the above formula (1), wherein the hydrocarbon group may be linear or cyclic.

Specific examples of the compound having this group include methoxytrimethylsilane, hexamethyldisiloxane,
Pentamethyldisiloxane and the like.

(H) Ether compound (2) -BOA ³ (10) In the formula (10), A ³ and B are represented by the formulas (8) and (9), respectively. The same as the group. Specific examples of the compound having this group include methoxymethyltrimethylsilane.

(I) Silane compound -D (11) In the formula (11), D represents a halogen atom, a hydrogen atom,
Any group selected from the group consisting of a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an acetyl group, and a Si-containing group represented by the formula (1). The hydrocarbon group is
It may be chain-like or cyclic, and a part of the hydrogen atoms may be substituted with a halogen atom or an alkoxy group.

Specific examples of the compound having this group include trimethylchlorosilane, butyldiphenylchlorosilane, trifluoromethyltrimethylsilane, acetyltrimethylsilane, 3-trimethylsilylcyclopentene, allyltrimethylsilane, vinyltrimethylsilane and the like.

(J) Carbamate compound

Embedded image In the formula (12), A ³ is the same as the group shown in the formula (9), and A ⁴ is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms.

Specific examples of the compound having this group include methyl-N-trimethylsilylcarbamate, methyl-
N, N-bistrimethylsilyl carbamate, ethyl-
N-trimethylsilyl carbamate, methyl-N-triethylsilyl carbamate, vinyl-N-trimethylsilyl carbamate and the like can be mentioned.

(K) Chain carbonate compound

Embedded image In the formula (13), A ⁴ is the same as the group represented by the formula (12).

Specific examples of the compound having this group include methyltrimethylsilyl carbonate, allyltrimethylsilyl carbonate, ethyltrimethylsilyl carbonate and the like.

(1) Other compounds -BD (14) In the formula (14), B and D are each a group represented by the formulas (8) and (11). Is the same. Specific examples of the compound having this group include hexamethyldisilazane.

In the present invention, among the compounds having a Si-containing group, (b), (c), (d), (i),
The compounds (j) and (k) are preferred. Among them, particularly, N-trialkylsilyl imidazole, tris (trialkylsilyl) phosphate, 4-trialkylsilylmethyl-1,3-dioxolan-2-one,
Trialkylchlorosilane, trifluoroalkyltrialkylsilane, allyltrialkylsilane, diallyldialkylsilane, triallylalkylsilane, acetyltrialkylsilane, alkyl-N-trialkylsilyl carbamate, alkyl-N, N-bistrialkylsilyl carbamate, And any compound selected from the group consisting of alkyltrialkylsilyl carbonate.

Among them, more preferred specific examples are N-trimethylsilylimidazole, tris (trimethylsilyl) phosphate, allyltrimethylsilane, 4-trimethylsilylmethyl-1,3-dioxolan-2-one, methyl-N-trimethylsilylcarbamate, methyl -N, N-bistrimethylsilyl carbamate, and methyltrimethylsilyl carbonate can be mentioned. In the present invention, 3-trialkylsilyl-2-oxazolidinone such as 3-trimethylsilyl-2-oxazolidinone can also be preferably used. The Si compound may be used alone or in combination of two or more.

The Si compound represented by the formula (2) is chemically stable, has excellent acid resistance, is hardly oxidized even when left in the air, and reacts with water in a normal storage state. ,
It is unlikely to react with highly reactive substances such as lithium metal. Further, such a Si compound is physically stable, hardly thermally decomposed, has high flame retardancy, and has characteristics of being hardly subjected to electrochemical oxidation and reduction. On the other hand, since these Si compounds have a relatively high flash point, they have excellent fire safety.

In [0045] electrolytic electrolyte Solvent present invention, as the electrolyte solvent, wherein the Si compound is in a single, or used in the form of the mixed solvent combining the other solvents Si compound. When used as a mixed solvent, the Si compound represented by the formula (2) is contained in the solvent in an amount of 0.01 to 50% by weight, preferably 0.1 to 30% by weight.
It is desirable to be mixed. When the content is within this range, an electrolyte solvent which is electrochemically and physically stable is formed, and the solvent is improved in flame retardancy, which is preferable.

Other solvents that can be used in the mixed solvent include:
Any of the following exemplified cyclic carbonates, chain carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, phosphate esters, sulfur-containing compounds, etc. Can be used.

(1) Cyclic carbonates: ethylene carbonate (1,3-dioxolan-2-one), propylene carbonate (4-methyl-1,3-dioxolan-2-one), butylene carbonate (4,5- Dimethyl-1,3-dioxolan-2-one), vinylene carbonate and the like.

Further, a cyclic carbonate having a halogen atom-substituted alkyl group such as monofluoromethylethylene carbonate, difluoromethylethylene carbonate and trifluoromethylethylene carbonate may be used.

(2) Chain carbonates: dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate and the like.

(3) Cyclic esters: γ-butyrolactone, γ-valerolactone, 3-methyl-γ-butyrolactone, 2-methyl-γ-butyrolactone and the like.

(4) Chain esters: methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, methyl butyrate, methyl valerate and the like.

(5) Cyclic ethers: 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, 2-
Methyltetrahydrofuran, 3-methyl-1,3-dioxolan, 2-methyl-1,3-dioxolan and the like.

(6) Chain ethers: 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, dimethyl ether, methyl ethyl ether, dipropyl ether and the like.

(7) Phosphate esters: trimethyl phosphate, triethyl phosphate, triallyl phosphate and the like. (8) Sulfur-containing compounds: sulfolane and the like.

Among these solvents, the use of a cyclic carbonate and / or a phosphate is preferred for further improving the charge / discharge cycle and flame retardancy. Also,
These solvents can be used alone or in combination of two or more.

[0056] As the electrolyte contained in the non-aqueous electrolytic solution according to the electrolytic electrolyte present invention,
Ammonium salts, phosphonium salts and others can be used. They can be used alone or in combination of two or more. Specifically, the following compounds can be exemplified.

(1) Ammonium salt: tetrafluoroboric acid 4
Butyl ammonium ((C ₄ H ₉ ) ₄ NBF ₄ ) 4-ethylammonium tetrafluoroborate ((C ₂ H ₅ ) ₄ NBF ₄ ) 3-ethyl monomethylammonium tetrafluoroborate ((C ₂ H ₅ )
₃ (CH ₃ ) NBF ₄ ), tetrabutylammonium hexafluorophosphate ((C ₄ H ₉ ) ₄ NPF ₆ ), tetraethylammonium hexafluorophosphate ((C ₂ H ₅ ) ₄ NPF ₆ ), 6 3ethyl 1-methylammonium fluorophosphate ((C ₂ H ₅ ) ₃ (CH ₃ ) NP
F ₆ ) and the like.

(2) Phosphonium salt: tetrafluoroboric acid 4
Butyl phosphonium _{((C 4 H 9) 4} PBF 4), 4 fluoride borate tetraethyl phosphonium _{((C 2 H 5) 4} PBF 4), 6 hexafluorophosphate 4-butyl phosphonium _{((C 4 H 9) 4} PP
F ₆ ), 4-ethylphosphonium hexafluorophosphate ((C
₂ H _{5) 4} PPF ₆₎ and the like. (3) In addition, electrolytes described in International Publication No. WO95 / 15572.

Among these compounds, (C ₄ H ₉ ) ₄ NB
It is preferable to use F ₄ , (C ₂ H ₅ ) ₄ NBF ₄ and (C ₂ H ₅ ) ₃ (CH ₃ ) NBF ₄ . The electrolyte is usually 0.1 to 3 in the electrolyte.
(Mol / liter), preferably in a concentration of 0.3 to 1.5 (mol / liter).

Electrodes and Capacitors The non-aqueous electrolyte according to the present invention can be generally used for capacitors including aluminum electrolytic capacitors, and can be particularly preferably used for electric double layer capacitors.

The structure of the electric double layer capacitor is composed of two electrodes, a separator and a generally corrosion-resistant electrolytic solution. Specifically, two electrodes are arranged so as to face each other with a separator interposed therebetween, and an electrolytic solution is filled between the electrodes and the porous separator and in the porous separator.

The electrode is formed of a material having a large surface area such as activated carbon and a binder such as a fluororesin. Activated carbon preferably used as the electrode material is a phenol-based, pitch-based, polyacrylonitrile-based, coconut shell-based,
Fibrous or powdered materials such as coke are generally used, and usually those having a specific surface area of 1000 (m ² / g) or more are preferable. The activated carbon is used after being activated by a method such as a steam activation method or an alkali activation method.

Examples of the binder include carboxymethylcellulose, polyvinylidene fluoride, polyvinylpyrrolidone,
Polyimide, polyvinyl alcohol, polyacrylic acid, etc. are used, and the electrode material is bound by this binder,
The electrodes are manufactured after being shaped.

Here, the electrode can be used after pretreatment with the above-mentioned non-aqueous electrolyte. As a pretreatment method, a method such as spraying a non-aqueous electrolyte on the electrode or immersing the electrode in the non-aqueous electrolyte can be used. By performing such a pretreatment, the electrode is more compatible with the non-aqueous electrolyte, and the electrode surface is stabilized, so that the capacitor capacity can be increased. The pretreated electrode is desirably used on at least one of the anode side and the cathode side, and can be used not only for electric double layer capacitors but also for capacitors in general.

In many cases, the electrode is usually used in combination with the above-mentioned electrode material (active material) and a current collector. As the current collector, for example, an aluminum foil is preferably used. On the other hand, as a separator, a porous film made of polyethylene or polypropylene, kraft paper,
Manila paper, glass filters and the like are preferably used.

The non-aqueous electrolytic solution of the present invention can be used for surface treatment of a current collector metal, thereby suppressing corrosion of the current collector.

The electric double layer capacitor is a wound type, a coin type described in Japanese Patent Publication No. 3-51284, etc .;
Various structures such as a laminated type described in -78291 are known, and the non-aqueous electrolyte according to the present invention can bring the same effect to any structure.

As an example, the configuration of a wound electric double layer capacitor element will be described. The capacitor element includes an anode-side polarizable electrode connected to an anode-side lead, and a cathode-side polarizable electrode connected to a cathode-side lead. , A separator is interposed therebetween, and the three members are wound together. A rubber sealing member is attached to the anode side lead wire and the cathode side lead wire.After impregnating this capacitor element with a driving electrolyte, it is inserted and stored in an aluminum bottomed cylindrical metal case. ing. By performing a horizontal drawing process and a curling process on the opening of the metal case, the sealing member is sealed in the opening of the metal case and hermetically sealed.

[0069]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

First, the production of the wound electric double layer capacitor element used in the examples and comparative examples will be described.
FIG. 1 is a perspective view showing a configuration of a wound electric double layer capacitor element, and FIG. 2 is a perspective view showing a state where the element is inserted into a metal case together with a sealing member.

As shown in FIG. 1, the capacitor element 1 is formed in a cylindrical shape by winding together the polarizable electrode 3 on the anode side, the polarizable electrode 5 on the cathode side, and the separator 6 interposed therebetween. did. Here, each polarizable electrode is prepared by adding acetylene black and carboxymethylcellulose to activated carbon powder, mixing and dispersing the mixed powder in water to form a slurry, and applying the slurry on a roughened aluminum foil. And dried.

The capacitor element 1 was impregnated with the electrolytic solution prepared in each of the examples, and the capacitor element 1 was then housed in an aluminum bottomed cylindrical case 8 as shown in FIG. On the other hand, the anode-side lead wire 2 is connected to the anode-side polarizable electrode 3, and the cathode-side lead wire 4 is connected to the cathode-side polarizable electrode 5, and each lead wire is pulled out through a rubber sealing member 7. Was. The sealing member 7 is attached to the opening of the cylindrical case 8, and then the opening is subjected to a horizontal drawing process and a curling process, and the opening is sealed by the sealing member 7. Obtained. This capacitor had a diameter of 18 mm and a height of 40 mm.

(Example 1) Propylene carbonate and N
-Trimethylsilyl imidazole in a weight ratio of 95:
2.71 g (0.07 g) of tetraethylammonium tetrafluoroborate ((C ₂ H ₅ ) ₄ NBF ₄ ) was added to the mixed solvent mixed at a ratio of 5.
125 mol) and an electrolyte concentration of 0.5 (mol /
25 ml of the electrolyte solution 1) was prepared. The amount of leakage current was measured for the obtained electrolytic solution, and the results are shown in Table 1.

Here, the amount of leakage current was measured by the following method. 1. The above-mentioned electrolyte solution was put into a three-electrode withstand voltage measuring cell using an activated carbon electrode as a working electrode and a counter electrode and an Ag / Ag + electrode as a reference electrode, and using a potentiogalvanostat.
A potential of 0 V was applied, and the amount of current when the amount of flowing current became constant was measured as the amount of leakage current.

Next, this electrolytic solution was used at the time of manufacturing the above-described capacitor, and an electric double layer capacitor rated at 2.3 V and 50 F was manufactured. Thereafter, 2.5 V was applied in an environment of 70 ° C., and the deformation of the cylindrical case due to the gas generated at that time was measured over time as the amount of deformation of the product appearance. The amount of deformation 500 hours after the start of the high-temperature load test is also shown in Table 1.

Example 2 The procedure of Example 1 was repeated, except that trimethyl phosphate was used instead of propylene carbonate. The amount of leakage current of the electrolytic solution and the amount of deformation of the product in a high-temperature load test were measured. The measurement was performed, and the results are shown in Table 1.

Example 3 The same procedure as in Example 1 was carried out except that 3-trimethylsilyl-2-oxazolidinone was used instead of N-trimethylsilylimidazole, and the leakage current of the electrolytic solution and the high-temperature load test were performed. Was measured for the product external deformation, and the results are also shown in Table 1.

Example 4 The procedure of Example 1 was repeated, except that tris (trimethylsilyl) phosphate was used in place of N-trimethylsilylimidazole. The amount of appearance deformation was measured, and the results are shown in Table 1.

Example 5 The same operation as in Example 4 was carried out except that trimethyl phosphate was used instead of propylene carbonate, and the leakage current of the electrolyte and the amount of deformation of the product in a high-temperature load test were measured. Was measured, and the results are shown in Table 1.

Example 6 The same operation as in Example 5 was performed, except that a mixed solvent in which trimethyl phosphate and tris (trimethylsilyl) phosphate were mixed at a weight ratio of 99: 1 was used. Was done. The amount of leakage current of the electrolytic solution and the amount of deformation of the product appearance in the high-temperature load test were measured, and the results are shown in Table 1.

Example 7 The procedure of Example 2 was repeated, except that trimethylchlorosilane was used instead of N-trimethylsilylimidazole. The amount of leakage current of the electrolytic solution and the amount of deformation of the product appearance in the high-temperature load test were measured, and the results are shown in Table 1.

Example 8 The procedure of Example 2 was repeated, except that allyltrimethylsilane was used in place of N-trimethylsilylimidazole. The amount of leakage current of the electrolytic solution and the amount of deformation of the product appearance in the high-temperature load test were measured, and the results are shown in Table 1.

Example 9 The procedure of Example 1 was repeated, except that methyl-N-trimethylsilylcarbamate was used instead of N-trimethylsilylimidazole. The amount of leakage current of the electrolytic solution and the amount of deformation of the product appearance in the high-temperature load test were measured, and the results are shown in Table 1.

Comparative Example 1 An electrolyte was prepared in the same manner as in Example 1, except that only propylene carbonate was used instead of the mixed solvent of propylene carbonate and N-trimethylsilylimidazole. The amount of leakage current of the obtained electrolyte was measured, and the results are shown in Table 1.

[0085]

[Table 1]

From Table 1, it can be seen that the electrolytes of Examples 1 to 9 are excellent in withstand voltage since they have a smaller amount of leakage current than the electrolytes of Comparative Example 1, and that the product deformation in the high temperature load test is also small. all right.

[0087]

Since the nonaqueous electrolyte according to the present invention uses an electrolyte solvent containing a Si compound, when it is used as an electrolyte for a capacitor, it generates less gas at high temperatures and has a high withstand voltage. And an electrolyte having excellent charge / discharge cycle characteristics. In addition, the electrolyte solvent has a high flash point and is excellent in fire safety.

A capacitor using such a non-aqueous electrolyte can have a high withstand voltage, excellent charge-discharge cycle characteristics, and a high energy density. In addition, this capacitor has a long life and is excellent in fire safety, and is therefore particularly suitable for an electric double layer capacitor.

Further, the electrode can be pre-treated with such a non-aqueous electrolyte. If such a treatment is performed, the electrode surface can be stabilized to increase the capacitance of the capacitor. Performance capacitors can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a wound electric double layer capacitor element used in an example.

FIG. 2 is a perspective view showing a state in which the wound electric double layer capacitor element used in the example is inserted into a metal case together with a sealing member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode side lead wire 3 Anode side polarizable electrode 4 Cathode side lead wire 5 Cathode side polarizable electrode 6 Separator 7 Sealing member 8 Bottomed cylindrical case 9 Winding type electric double layer capacitor

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Yoshinori Takamukai 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5H029 AJ05 AJ12 AM02 AM03 AM04 AM05 AM06 AM07 DJ06 DJ09 DJ16 EJ04 EJ11 HJ02

Claims (14)

[Claims] 1. A non-aqueous electrolytic solution for capacitors comprising an electrolyte and an electrolytic solvent containing a compound having a Si-containing group represented by the formula (1). Embedded image (Wherein, R ¹ , R ² and R ³ are monovalent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, and an oxyhydrocarbon group having 1 to 6 carbon atoms) Group, the hydrocarbon part of the hydrocarbon group or the oxyhydrocarbon group may be linear or cyclic, and the hydrocarbon part may be saturated or unsaturated, (A part of the hydrogen atoms of the hydrocarbon moiety may be substituted with halogen atoms, and R ¹ , R ² and R ³ may be the same or different.) 2. The method according to claim 1, wherein the R of the Si-containing group represented by the formula (1) is
^1, R ² and R ^3, the non-aqueous electrolyte solution for a capacitor according to claim 1, characterized in that a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms. 3. The method according to claim 1, wherein said Si-containing group represented by the formula (1)
^{2. A method according to claim 1} , wherein R ¹ , R ² and R ³ are the same alkyl group having 1 to 3 carbon atoms.
3. The non-aqueous electrolyte for a capacitor according to 1.). 4. The method according to claim 1, wherein the R of the Si-containing group represented by the formula (1) is
^1, R ² and R ³ are a methyl group, an ethyl group, and a capacitor for a non-aqueous electrolyte solution according to claim 1, characterized in that any group selected from the group consisting of a trifluoromethyl group. 5. The compound having a Si-containing group represented by the above formula (1) is represented by the following formula (2): The non-aqueous electrolytic solution for a capacitor according to any one of claims 1 to 4, wherein X is any group selected from the group consisting of the following formulas (3) to (14). . (A) (In the formula (3), part of the hydrogen atoms may be substituted with a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, or a halogen atom. (B) (In the formula (4), part of the hydrogen atoms may be substituted with a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, or a halogen atom. ) (C) (In the formula (5), A ¹ and A ² are a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms or a Si-containing group represented by the above formula (1) and are the same as each other. (D) (In the formula (6), a part of the hydrogen atoms bonded to the carbon atoms constituting the ring is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, a halogen atom, Atom or Si represented by the above formula (1)
(N may be 0, 1 or 2) (e) (In the formula (7), a part of the hydrogen atoms bonded to the carbon atoms constituting the benzene ring is a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, (It may be substituted with a halogen atom or a Si-containing group represented by the above formula (1).) (F) (In the formula (8), B represents —NH—, —N (CH ₃ )
—, —CH ₂ —, —CO—, —S—, —SO ₂ —, a divalent group selected from the group consisting of: and a hydrogen atom bonded to a carbon atom constituting a benzene ring. A part thereof is substituted by a saturated or unsaturated hydrocarbon group having 1 to 4 carbon atoms, an alkoxy group, an amino group, a cyano group, a nitro group, a halogen atom or a Si-containing group represented by the above formula (1). in may ^{be) (g) -O-a 3} ········· (9) ( formula (9), a ³ is carbonized monovalent saturated or unsaturated having 1 to 6 carbon atoms A hydrogen group or a Si-containing group represented by the above formula (1), and the hydrocarbon group may be a chain or a ring.) (H) -BOA ³ (10) (In the formula (10), A ³ and B are each represented by the formula (8)
(I) -D (11) (In the formula (11), D represents a halogen atom, a hydrogen atom, a carbon atom Any one group selected from the group consisting of a monovalent saturated or unsaturated hydrocarbon group represented by Formulas 1 to 6, an acetyl group, and a Si-containing group represented by the formula (1), (A part of hydrogen atoms may be substituted with a halogen atom or an alkoxy group.) (J) (In the formula (12), A ³ is the same as the group represented by the formula (9), and A ⁴ is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms.) (K) Formula 10 (In the formula (13), A ⁴ is the same as the group represented by the formula (12)) (1) -BD (14) (in the formula (14) , B and D are the same as the groups represented by the formulas (8) and (11), respectively) 6. A compound represented by the above formula (2),
Trialkylsilyl imidazole, tris (trialkylsilyl) phosphate, 4-trialkylsilylmethyl-1,3-dioxolan-2-one, trialkylchlorosilane, trifluoroalkyltrialkylsilane, allyltrialkylsilane, diallyldialkylsilane, Triallylalkylsilane, acetyltrialkylsilane, alkyl-N-trialkylsilylcarbamate, alkyl-N, N-bistrialkylsilylcarbamate, alkyltrialkylsilyl carbonate,
The non-aqueous electrolytic solution for a capacitor according to claim 5, which is any compound selected from the group consisting of and 3-trialkylsilyl-2-oxazolidinone. 7. The compound represented by the formula (2) is
Trimethylsilyl imidazole, tris (trimethylsilyl) phosphate, allyltrimethylsilane, 4-trimethylsilylmethyl-1,3-dioxolan-2-one, methyl-N-trimethylsilylcarbamate, methyl-N, N-bistrimethylsilylcarbamate, methyltrimethylsilyl carbonate, and 6. A compound selected from the group consisting of 3-trimethylsilyl-2-oxazolidinone.
3. The non-aqueous electrolyte for a capacitor according to 1.). 8. The electrolyte solvent according to claim 1, wherein the electrolyte solvent is a mixed solvent of a compound represented by the formula (2) and a cyclic carbonate and / or a phosphate.
The non-aqueous electrolyte for a capacitor according to any one of the above. 9. The capacitor for a capacitor according to claim 1, wherein said electrolyte solvent contains 0.01 to 50% by weight of a compound represented by the formula (2). Non-aqueous electrolyte. 10. The non-aqueous electrolytic solution for a capacitor according to claim 1, wherein the capacitor is an electric double layer capacitor. 11. A capacitor comprising the non-aqueous electrolyte for a capacitor according to claim 1. 12. An electric double layer capacitor comprising the non-aqueous electrolyte for a capacitor according to claim 1. 13. An electrode for a capacitor, wherein the electrode of the capacitor is pretreated with the electrolyte solvent according to any one of claims 1 to 9. 14. A capacitor, wherein at least one electrode constituting the capacitor is the capacitor electrode according to claim 13.