JPH1154379A - Electrolyte and electrochemical element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat resistance and solubility to solvent, by combining electrolytic anions having electrochemically high withstand voltage with cations shown by a specified chemical formula. SOLUTION: An electrolytic solution is salt whose cation component is compound shown by a formula I or II. R<1> is a 1-20C hydrocarbon group or a hydrogen atom which may be substituted by a hydroxy group. R<2> , R<3> , R<4> and R<5> are 1-10C hydrocarbon groups which may have a hydroxy group, an amino group, a nitro group, a siano group, a carboxyl group, an ether group and aldehyde droup, respectively. A part or the whole of R<1> , R<2> , R<3> , R<4> and R<5> may mutually couple and form a ring. The anion constituting the salt is one or more kinds out of 2C or more perfluoro alkane sulfonic acid ion, per chloro alkane sulfonic acid ion, perfluoro alkane carbonic acid ion, perchloro alkane carbonic acid ion, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution used for an electrochemical device such as an electric double layer capacitor, an aluminum electrolytic capacitor and an electrochromic display device, and an electrochemical device using the same.

[0002]

2. Description of the Related Art Conventionally, as an electrolytic solution used for the above-mentioned electrochemical element, for example, a quaternary ammonium salt of perchloric acid as a solute as an electrolytic solution for an electric double layer capacitor (Japanese Patent Publication No. 54-9704). the BF ₄ salt or PF ₆ salt of quaternary ammonium which a solute (JP-B-52-40
No. 025), 4 of perfluoroalkanesulfonic acid
Sodium-grade ammonium salt (Japanese Patent Publication No. 6-175)
No. 0 publication) and the like. Electric double layer capacitors using these electrolytes have the problem that the rubber sealing body is deteriorated due to excessive hydroxide ions generated by the electrolysis of quaternary ammonium on the cathode side, and the sealing performance is significantly reduced. In addition, since the withstand voltage of the electrolyte is low, the capacity of the electric double layer is limited, and further improvement is desired. In order to solve these problems, we have already proposed an electrolytic solution using a salt of an amidine compound as a solute (WO 95/15572, republished patent).

[0003]

However, this electrolytic solution has the effect of suppressing the deterioration of the rubber sealing body and maintaining the sealing performance, but has insufficient heat resistance and insufficient solubility in a solvent. Therefore, there is a problem that the electrolytic mass in the solution is limited and the electric conductivity is not sufficiently high.

The present inventors have intensively studied an electrolytic solution having a higher level of heat resistance, solubility in a solvent, and electric conductivity, and an electrochemical device using the electrolytic solution.

[0005]

In order to solve the above-mentioned problems, the present invention provides a solution comprising a salt (A) containing a compound (a) represented by the following formula (3) or (4) as a cation component. Wherein the anion (b) constituting the salt (A) is a perfluoroalkanesulfonic acid ion having 2 or more carbon atoms, a perchloroalkanesulfonic acid ion, a perfluoroalkanecarboxylic acid ion, or a perchloroalkanecarboxylic acid. The electrolyte solution is at least one selected from an ion, a bis (perfluoroalkylsulfonyl) imide ion, and a tris (perfluoroalkylsulfonyl) methide ion.

According to the structure of the present invention described above, the use of an electrolyte anion having a high withstand voltage electrochemically and the combination with the cation represented by the chemical formula (3) or (4) make it possible to reduce the heat resistance and the solvent. Thus, it is possible to provide an electrolytic solution having high reliability and capable of forming a high-performance electrochemical element.

[0007]

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[0008]

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[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention relates to a solution comprising a salt (A) having a compound (a) represented by the formula (3) or (4) as a cation component as a solute. Anion (b) constituting the salt (A)
Is a perfluoroalkanesulfonic acid ion having 2 or more carbon atoms, a perchloroalkanesulfonic acid ion, a perfluoroalkanecarboxylic acid ion, a perchloroalkanecarboxylic acid ion, a bis (perfluoroalkylsulfonyl) imide ion, a tris (perfluoroalkylsulfonyl) ion ) An electrolytic solution that is at least one selected from methide ions. According to this configuration, heat resistance is high,
In addition, the electrolyte can exhibit high electrical conductivity and can have high stability at low temperatures.

The invention according to claim 2 uses bis (trifluoromethylsulfonyl) imide ion as bis (perfluoroalkylsulfonyl) imide ion or tris (perfluoroalkylsulfonyl) imide ion.
Tris (trifluoromethylsulfonyl) methide ion is used as the methide ion. According to this configuration, the heat resistance is particularly high, the electric conductivity is high, and the stability of the electrolyte at a low temperature is particularly high. It can constitute an electrolytic solution.

According to a third aspect of the present invention, there is provided an electrochemical device using the electrolytic solution according to the first or second aspect,
According to this configuration, the electrolytic solution has high heat resistance, high electrical conductivity, and high stability of the electrolytic solution at a low temperature. Therefore, the electrochemical element using this electrolytic solution has high heat resistance. It is high, has low internal resistance, and exhibits stable characteristics over a wide temperature range.

According to a fourth aspect of the present invention, the electrochemical element is specified as an electric double layer capacitor. According to this structure, the electrolytic solution has high heat resistance, high electric conductivity and low temperature. Since the stability of the electrolytic solution is high, an electric double layer capacitor using this electrolytic solution has high heat resistance, low internal resistance, and shows stable characteristics over a wide temperature range.

Hereinafter, an embodiment of the present invention will be described. The electrolyte of the present invention is based on an electrolyte comprising a solution containing a salt (A) having the compound (a) represented by the chemical formula (3) or (4) as a cation component as a solute. Perfluoroalkanesulfonic acid ion having 2 or more carbon atoms, perchloroalkanesulfonic acid ion, perfluoroalkanecarboxylic acid ion, perchloroalkanecarboxylic acid ion, bis (perfluoroalkylsulfonyl) imide ion, tris (Perfluoroalkylsulfonyl) An electrolyte solution that is at least one selected from methide ions.

The anion (b) constituting the salt (A)
Are the anions contained in the organic acids described in (1) to (4) below and the organic anions described above.

Perfluoroalkanesulfonic acid having 2 or more carbon atoms, such as pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, etc. Perchloroalkanesulfonic acid, trichloromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, etc. Fluoroalkanecarboxylic acid ・ Trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutanoic acid, etc.Perchloroalkanecarboxylic acid ・ Trichloroacetic acid, pentachloropropionic acid, heptachlorobutanoic acid, etc.Perfluoroalkylsulfonylimide or perfluoroalkylsulfonylmethide , Bis (trifluoromethylsulfonyl) imide, tris (trifluoromethylsulfonyl) methide B methylsulfonyl) imide, tris (trifluoromethylsulfonyl) methide.

The molecular weight of the above anion is usually 500 or less. If the molecular weight exceeds 500, the solubility in the electrolyte solvent decreases.

The cation component (a) constituting the salt (A) used in the present invention includes cations exemplified below.

Imidazolium compounds: 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,2
3-trimethylimidazolium, 1,2,3,4-tetramethylimidazolium, 1-benzyl-3-methylimidazolium, 1,3-dimethyl-2-phenylimidazolium, etc. Imidazolinium compounds: 1, 2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1,1,2-trimethylimidazolinium,
1,1,2,4-tetramethylimidazolinium, etc.-Tetrahydropyrimidinium-based compound: 1,3-dimethyl-1,4,5,6-tetrahydropyrimidium, 1,
2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1-methyl-1,8-diazabicyclo [5.4.0] undecene-7, 1-methyl-1,5-
Preferred among these are imidazolium-based compounds and tetrahydropyrimidium-based compounds, and particularly preferred are 1,3-dimethylimidazolium, 1,3-dimethylimidazolium, and the like.
3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1-methyl -1,8-diazabicyclo [5.4.0] undecene-7,1-methyl-1,
5-diazabicyclo [4.3.0] nonene-5.

The electrolytic solution of the present invention comprises a solution of the salt (A). As the solvent, an organic solvent and / or water can be usually used. Specific examples of the organic solvent are as follows, and two or more kinds can be used in combination. -Alcohols: methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, furfuryl alcohol, ethylene glycol, propylene glycol, glycerin, etc.-Ethers: ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether,
Diethylene glycol dimethyl ether, 1,3-dioxolan, 1,4-dioxane, etc. Amides: N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, N,
N-dimethylpropionamide, hexamethylphosphorylamide, N-methylpyrrolidone, etc. Lactones: γ-butyrolactone, α-acetyl-γ
-Butyrolactone, β-butyrolactone, γ-valerolactone, δ-valerolactone, etc. ・ Nitriles: acetonitrile, acrylonitrile, etc. ・ Carbonates: ethylene carbonate, propion carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, etc. ・ Sulfoxides: dimethyl sulfoxide , Sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, etc. Other organic solvents: N-methyl-2-oxazolidinone, 3,5-dimethyl-2-oxazolidinone, 1,3
-Dimethyl-2-imidazolidinone, N-methylpyrrolidone, aromatic solvents (toluene, xylene, etc.), paraffinic solvents (normal paraffin, isoparaffin, etc.) Preferred solvents include ethers, lactones, nitriles , Carbonates, sulfoxides, and the like. Particularly preferred are ethylene carbonate, propion carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, 3-methylsulfolane, and 2-methylsulfolane. , 4-dimethylsulfolane, acetonitrile, tetrahydrofuran, 1,3
-Dioxolane and the like.

Various additives can be added to the electrolytic solution of the present invention, if necessary. Examples of the additive include a phosphoric acid derivative, a boric acid derivative, and a nitro compound.

The content of the salt (A) in the electrolytic solution of the present invention is usually 1 to 70% by weight, preferably 5 to 40% based on the weight of the electrolytic solution.

The electrochemical device of the present invention uses the electrolytic solution of the present invention. (Table 1) shows the composition of the electrolytic solutions of Embodiments 1 to 5 of the present invention and Conventional Examples 1 to 3. (Table 2) shows the results of measuring the electrical conductivity of the electrolytes of Embodiments 1 to 5 of the present invention and Conventional Examples 1 to 3 at a temperature of −20 ° C.

[0023]

[Table 1]

[0024]

[Table 2]

As is clear from Table 2, the electrolytes of Embodiments 1 to 5 of the present invention exhibit higher electric conductivity than those of Conventional Examples 1 to 3.

Next, a wound type electric double-layer capacitor (rated voltage 2.5 V-capacitance 10 F, size; using the electrolytic solutions of Embodiments 1 to 5 of the present invention and Conventional Examples 1 to 3;
φ18 mm L35 mm). Then, when a voltage of 2.5 V was applied to these electric double layer capacitors at 85 ° C., the capacitance change rate after 500 hours was measured. The measurement results are shown in (Table 3).

[0027]

[Table 3]

As is clear from Table 3, the electric double layer capacitors using the electrolytes of the first to fifth embodiments of the present invention are different from the electric double layer capacitors using the electrolytes of the first to third conventional examples. An electric double layer capacitor having a smaller rate of change in capacitance and higher heat resistance can be constructed.

Next, the first to fifth embodiments of the present invention described above.
And a wound type electric double layer capacitor (rated voltage 2.5 V-capacitance 10 F,
The internal resistance at −20 ° C. of a size of φ18 mm L35 mm) was measured. The measurement results are shown in (Table 4).

[0030]

[Table 4]

As is evident from Table 4, the electric double layer capacitors using the electrolytic solutions of the first to fifth embodiments of the present invention are different from the electric double layer capacitors using the electrolytic solutions of Conventional Examples 1 to 3. Also, an electric double layer capacitor having a low internal resistance at −20 ° C. and being stable at a low temperature can be formed.

Next, the first to fifth embodiments of the present invention described above.
The reliability was evaluated after 2,000 hours when a voltage of 3.0 V was applied at 70 ° C. to a wound electric double-layer capacitor using the electrolytic solution of Conventional Examples 1 to 3, and after the test was completed, The state of the sealing rubber surface constituting the sealing body of the double-layer capacitor was observed. The observation results are shown in (Table 5).

[0033]

[Table 5]

As is clear from Table 5, in the electric double layer capacitor using the electrolytic solution of Embodiments 1 to 5 of the present invention, the electrolytic solution has an excessive hydroxylation that leads to a decrease in the sealing performance of the sealing body. Since it has the effect of eliminating ions, a highly reliable electric double layer capacitor can be formed without deteriorating the sealing body.

Although the wound type electric double layer capacitor has been described in the embodiment of the present invention, the same effect as that of the embodiment of the present invention can be obtained by applying the present invention to other electrochemical devices. It is something that can be done.

[0036]

As described above, the electrolytic solution of the present invention comprises an electrolytic solution comprising a salt (A) having the compound (a) represented by the chemical formula (3) as a cation component and a solute as a solute. Wherein the anion (b) constituting the salt (A) is a perfluoroalkanesulfonic acid ion having 2 or more carbon atoms, a perchloroalkanesulfonic acid ion, a perfluoroalkanecarboxylic acid ion, a perchloroalkanecarboxylic acid ion, a bis ( An electrolytic solution that is at least one selected from perfluoroalkylsulfonyl) imide ion and tris (perfluoroalkylsulfonyl) methide ion. According to this configuration, the effect of suppressing the generation of strong alkali components is maintained. An electrolyte having high heat resistance, high electrical conductivity, and high stability of the electrolyte at low temperatures can be obtained. It is.

Continued on the front page (72) Inventor Hideki Shimamoto 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yukiya Kobayashi 1-11-11 Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto-shi, Kyoto (72) Inventor Tomoji Nakano 1 at Sanyo Chemical Industry Co., Ltd., 11-1, Hitotsubashi-Honcho, Higashiyama-ku, Kyoto-shi, Kyoto Prefecture (72) Inventor Hideo Seike 1 Sanyo Kasei Kogyo Co., Ltd., 11-11 Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto-shi, Kyoto

Claims (4)

[Claims] 1. An electrolyte comprising a solution containing a salt (A) having the compound (a) represented by the formula (1) or (2) as a solute as a solute and an anion (S) constituting the salt (A) b) is a perfluoroalkanesulfonate ion having 2 or more carbon atoms, perchloroalkanesulfonate ion, perfluoroalkanecarboxylate ion, perchloroalkanecarboxylate ion, bis (perfluoroalkylsulfonyl) imide ion, tris (perfluoroalkyl An electrolyte solution that is at least one selected from sulfonyl) methide ions. Embedded image Embedded image 2. The method according to claim 1, wherein a bis (trifluoromethylsulfonyl) imide ion is used as the bis (perfluoroalkylsulfonyl) imide ion, or a tris (trifluoromethylsulfonyl) methide ion is used as the tris (perfluoroalkylsulfonyl) methide ion. Item 2. The electrolytic solution according to Item 1. 3. An electrochemical device using the electrolytic solution according to claim 1 or 2. 4. The electrochemical device according to claim 3, wherein the electrochemical device is an electric double layer capacitor.