JPH1154377A - Electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably prevent a leakage of an alkali electrolyte, by a method wherein a non-water system electrolyte liquid impregnated in a polarization electrode is constructed by melting a compound indicated by a specified chemical formula in a polar non-proton solvent by use of salt being a cation component as an electrolyte. SOLUTION: An electric double layer capacitor has a polarization electrode and a non-water system electrolyte liquid impregnated in the polarization electrode, and the non-water system electrolyte liquid is constructed by melting a compound indicated by formula I or formula II in a polar non-proton solvent by use of salt being a cation component as an electrolyre (R<1> is a hydrocarbon base or a hydrogen atom of the number of carbons 1 to 20 which may be replaced with a hydroxyl base; and R<2> , R<3> , R<4> and R<5> denote hydrocarbon bases of carbons 1 to 10 which may each have a hydroxyl base, an amino base, a nitro base, a cyano base, a carboxyl base and an ether base, or an aldehyde base. Any or all of R<1> , R<2> , R<3> , R<4> and R<5> are coupled to each other to form a ring.). As a result, it is possible to eliminate hydroxide ions on a lead surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor used for various electronic devices.

[0002]

2. Description of the Related Art In general, an electric double layer capacitor of this type constitutes a capacitor element by opposing a pair of polarizable electrodes with a separator interposed therebetween, and impregnating the capacitor element with an electrolytic solution. Make up. The polarizable electrode is obtained by applying an electrode slurry to an aluminum foil or a copper foil to a predetermined thickness, and the electrode slurry is a mixture of activated carbon, graphite or a polyacene organic semiconductor and carbon black, acetylene black or Ketjen black. Is made by adding PTFE, CMC or the like as a binder to the mixture and moistening it with pure water or alcohol.

[0003] Solvents for the electrolyte include propylene carbonate, γ-butyrolactone, ethylene carbonate,
Sulfolane, acetonitrile, dimethyl carbonate,
Either one or a mixture of two or more of diethyl carbonate and methyl ethyl carbonate is used. As the electrolyte cation, quaternary ammonium or quaternary phosphonium is used, while as the electrolyte anion, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , CF
₃ SO ₃ ^- or N (CF ₃ SO ₂ ) ₂ ^- is used.

It is known that an electric double layer capacitor having a high withstand voltage can be obtained by using sulfolane or a derivative thereof as a solvent for an electrolytic solution (Japanese Patent Laid-Open No. 62-2377).
No. 15). And again, N, N, N'-
It is known that the use of a quaternary salt of a compound having a substituted amidine group can suppress the generation of hydroxide ions that lower the sealing performance of the sealing body, and furthermore use a tertiary ammonium salt for the electrolyte. It is also known that the deterioration of the sealing performance of the sealing body can be suppressed by the above method (see JP-A-7-326546).

[0005]

However, in the above-mentioned conventional electric double layer capacitor, since a quaternary ammonium salt or a quaternary phosphonium salt is used as an electrolyte of the non-aqueous electrolyte, this non-aqueous electrolyte is used. When an electric double layer capacitor is manufactured using an electrolytic solution, the withstand voltage at 60 ° C. is approximately 2.3 V to 2.5 V. In this case, when a voltage higher than that is applied, the capacitance, internal resistance, and external dimensions change. Has a problem that the size becomes larger.

Further, the electrolytic solution described in Japanese Patent Application Laid-Open No. 62-237715 has a problem that the internal resistance of the electric double layer capacitor increases because the electrolytic solution has a lower electric conductivity than the conventional electrolytic solution. Since quaternary ammonium or quaternary phosphonium is used as the electrolyte cation, the sealing body is formed by a strong alkali component generated on the surface of the cathode-side polarizable electrode or the surface of the lead-out lead connected to the cathode-side polarizable electrode. The sealing performance of
There was a problem that the electrolyte leaked out of the electric double layer capacitor.

Further, when a quaternary salt of a compound having an N, N, N'-substituted amidine group is used as an electrolyte of an electrolyte for an electric double layer capacitor, the electrolyte cation itself forms an electrochemical reaction on the surface of the polarizable electrode. Some of them cause a reaction, which causes a problem such as a change in internal resistance and a change in capacitance of the electric double layer capacitor.

Further, when a tertiary ammonium salt or a tertiary phosphonium salt described in JP-A-7-326546 is used as an electrolyte of an electrolytic solution for an electric double layer capacitor, the electric double layer capacitor is There is a problem that heat resistance and withstand voltage are remarkably inferior to those of conventional electric double layer capacitors using a quaternary ammonium salt or a quaternary phosphonium salt as an electrolyte.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. It is possible to improve the withstand voltage of a non-aqueous electrolyte and to improve the withstand voltage of the surface of the cathode-side polarizable electrode or the drawer connected to the cathode-side polarizable electrode. It is an object of the present invention to provide an electric double layer capacitor capable of eliminating a strong alkali component generated on the surface of a lead, thereby preventing a decrease in sealing performance of a sealing body.

[0010]

In order to achieve the above object, an electric double layer capacitor according to the present invention has a polarizable electrode and a non-aqueous electrolyte impregnated in the polarizable electrode. The electrolytic solution is composed of a polar aprotic solvent obtained by dissolving, as an electrolyte, a salt having a compound represented by the following formula (Chemical Formula 6) or (Chemical Formula 7) as a cation component. The withstand voltage of the solution can be improved, and the strong alkaline component generated on the surface of the cathode-side polarizable electrode or the surface of the lead lead connected to the cathode-side polarizable electrode can be eliminated. It can prevent a decrease in the sealing performance of the body.

[0011]

Embedded image

[0012]

Embedded image

[0013]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention comprises a polarizable electrode and a non-aqueous electrolyte impregnated in the polarizable electrode, wherein the non-aqueous electrolyte is a polar non-proton. It is composed of a solvent obtained by dissolving, as an electrolyte, a salt having the compound represented by (Chem. 6) or (Chem. 7) as a cation component in a solvent. According to this constitution, (Chem. 6) or (Chem. 7) The electrochemically stable potential region (potential window) of the electrolyte is widened by the effect of the electrolyte cation component shown in (2). Shows high withstand voltage, and furthermore, the electrolyte cation component of the non-aqueous electrolyte solution,
In order to eliminate hydroxide ions that are strong alkali components generated on the surface of the cathode-side polarizable electrode or the surface of the extraction lead connected to the cathode-side polarizable electrode, the sealing performance of the sealing body is deteriorated by the strong alkali component. Without
Thereby, leakage of the alkaline electrolyte can be reliably prevented.

According to a second aspect of the present invention, the carbon material used for the polarizable electrode is made of one or a mixture of two or more of activated carbon, graphite, and polyacene organic semiconductor. According to this, a large-capacity electric double-layer capacitor can be obtained because the surface area of the polarizable electrode is very large, and the contact area between the polarizable electrode and the electrolyte is large, so that the electrochemical reaction that occurs on the surface of the polarizable electrode The amount of reactants is remarkably large, and therefore, the change in characteristics of the electric double layer capacitor manufactured using the polarizable electrode made of these carbon materials is susceptible to the influence of the width of the potential window of the electrolytic solution. In an electric double layer capacitor using a carbon material having a large surface area, the electrolyte cation component represented by (Chem. 6) or (Chem. 7) according to claim 1 is used. Effect is large when the use, in which a high electric double layer capacitor with a large capacity in and withstand voltage by these configurations can be obtained.

According to a third aspect of the present invention, the water content of the non-aqueous electrolyte is set to 3000 ppm or less, and when the water content of the non-aqueous electrolyte exceeds 3000 ppm, the water content of the electrolyte is reduced. The breakdown voltage of the electrolytic solution is reduced by the decomposition, and the effect of increasing the withstand voltage obtained by the configuration according to claim 1 or 2 is no longer obtained. Therefore, the water content of the non-aqueous electrolytic solution is appropriately 3000 ppm or less. It is considered to be.

The invention according to claim 4 uses an electrolytic solution obtained by dissolving a salt of an electrolyte cation component in which the cation component represented by formula (6) is (formula 8) in a polar aprotic solvent. According to this configuration, the salt of the electrolyte cation component represented by the chemical formula (8) is electrochemically stable and has a high withstand voltage, and has high solubility in a polar aprotic solvent. Is obtained by impregnating a polarizable electrode having a carbon material composed of one or a mixture of two or more of activated carbon, graphite, and polyacene-based organic semiconductors with an electrolyte solution comprising a salt of an electrolyte cation component represented by Double-layer capacitors can provide higher capacitance than conventional electric double-layer capacitors.With these configurations, they have high withstand voltage, high stability at low temperatures, and The amount is of a large electric double layer capacitor obtained.

[0017]

Embedded image

The invention according to claim 5 uses an electrolytic solution obtained by dissolving a salt of an electrolyte cation component in which the cation component represented by (Chemical Formula 6) is (Chemical Formula 9) in a polar aprotic solvent. According to this configuration, the salt of the electrolyte cation component represented by the chemical formula (9) is electrochemically stable, exhibits a high withstand voltage, and has high mobility in a polar aprotic solvent. The electrolytic solution using the salt of the component has a high electric conductivity, and an electric double layer capacitor having a high withstand voltage and a low internal resistance can be obtained by these configurations.

[0019]

Embedded image

The invention according to claim 6 uses an electrolytic solution obtained by dissolving a salt of an electrolyte cation component in which the cation component represented by (Chemical Formula 6) is (Chemical Formula 10) in a polar aprotic solvent. According to this configuration, the salt of the electrolyte cation component represented by Chemical Formula 10 is electrochemically stable, exhibits high withstand voltage, and exhibits high heat resistance.
With these configurations, an electric double layer capacitor having high withstand voltage and high heat resistance can be obtained.

[0021]

Embedded image

According to a seventh aspect of the present invention, the cation component represented by the formula (6) is 1-methyl-3-ethylimidazolium, and the salt of the electrolyte cation component is dissolved in a polar aprotic solvent. According to this configuration, 1-methyl-3-ethylimidazolium has high solubility in polar aprotic solvents such as propylene carbonate, γ-butyrolactone, and sulfolane.
It has high electrical conductivity, high heat resistance in the polar aprotic solvent, high electrochemical stability,
Of electricity obtained by impregnating a polarizable electrode having a carbon material composed of any one or a mixture of two or more of activated carbon, graphite and a polyacene-based organic semiconductor with an electrolyte solution comprising -methyl-3-ethylimidazolium Double-layer capacitors have higher capacitance than conventional electric double-layer capacitors.With these configurations, they have a long life, high withstand voltage, high stability at low temperatures, and a large capacitance. An electric double layer capacitor is obtained.

Hereinafter, an embodiment of the present invention will be described. The basics of the electric double layer capacitor of the present invention include a polarizable electrode and a non-aqueous electrolytic solution impregnated in the polarizable electrode, and the non-aqueous electrolytic solution is converted into a polar aprotic solvent. Alternatively, it is constituted by dissolving, as an electrolyte, a salt having the compound represented by the formula (7) as a cation component.

The polar aprotic solvent used in the present invention may be any one of propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, and acetonitrile. Mixtures of more than one species.

The electrolyte anions include BF ₄ ⁻ ,
PF ₆ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ or N (CF ₃ SO ₂ )
₂ ^- include mixtures of any one or more of.

The electrolyte solution of the present invention may contain a sub-solvent if necessary. Examples of the auxiliary solvent include tetrahydrofuran, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and the like.

In the electrolyte of the present invention, when the concentration of the electrolyte is 0.1 mol / kg or less, the electric conductivity of the electrolyte is remarkably reduced, while the concentration of the electrolyte is 3.0 mol / kg or more. In the case of (1), the electrolyte is precipitated in the solvent at a low temperature exceeding the saturation solubility. Therefore, the concentration of the electrolyte is preferably in the range of 0.1 to 0.3 mol / kg, In order to obtain the stability of the electrolytic solution, in particular, 0.5 to
A range of 2.0 mol / kg is preferred.

The polarizable electrode used in the present invention contains a carbon material composed of one or a mixture of two or more of activated carbon, graphite, and polyacene-based organic semiconductor.

The water contained in the non-aqueous electrolyte of the present invention is 3
000 ppm or less. (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 electric conductivity at a temperature of 30 ° C. for the electrolyte solutions of Embodiments 1 to 5 of the present invention and Conventional Examples 1 to 3.

[0030]

[Table 1]

[0031]

[Table 2]

As is clear from Table 2, the electrolytes according to the first to fifth embodiments of the present invention have higher electric conductivity than the electrolytes according to the conventional examples 1 to 3.

Next, Embodiment 1 of the present invention and Conventional Example 1
The potential window of each electrolyte was measured by cyclic voltammetry using the above electrolyte. FIG. 1 shows the measurement result of the first embodiment of the present invention, and FIG. 2 shows the measurement result of the first conventional example. The measurement conditions for cyclic voltammetry are shown in (Table 3).

[0034]

[Table 3]

As is clear from the comparison between FIG. 1 and FIG. 2, the electrolytic solution according to the first embodiment of the present invention shown in FIG. 1 has a wider potential window and a higher potential window than the electrolytic solution of Conventional Example 1 shown in FIG. It turns out that it has withstand voltage.

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 60 ° C., the leakage current value and the capacitance after 500 hours were measured. The measurement results are shown in (Table 4).

[0037]

[Table 4]

As is clear 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 the conventional examples 1 to 3. In comparison with this, the leakage current value is small and the capacitance is high. From these facts, an electric double layer capacitor having a high withstand voltage and a large capacity 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).

[0040]

[Table 5]

As is clear from Table 5, the electric double layer capacitors using the electrolytes according to Embodiments 1 to 5 of the present invention have excessive hydroxylation in the electrolyte which leads to a decrease in the sealing performance of the sealing body. Since it contains an electrolyte cation component represented by (Chemical formula 6) or (Chemical formula 7) capable of eliminating ions, a highly reliable electric double layer capacitor can be formed without deteriorating the sealing body. Things.

In the first to fifth embodiments of the present invention, a wound type electric double layer capacitor has been described. However, the present invention is applied to an electrolytic solution of an electric double layer capacitor having another structure such as a coin type or a laminated type. Also, Embodiments 1 to 5 of the present invention
The same effect as described above can be obtained.

[0043]

As described above, the electric double layer capacitor of the present invention has a polarizable electrode and a non-aqueous electrolytic solution impregnated in the polarizable electrode, wherein the non-aqueous electrolytic solution is a polar aprotic solvent. And a salt obtained by dissolving, as an electrolyte, a salt having a compound represented by the formula (6) or (Chem. 7) as a cation component. According to this structure, the compound represented by the formula (6) or (7) is used. Since the electrochemically stable potential region (potential window) of the electrolyte is broadened by the influence of the electrolyte cation component shown, the electric double-layer capacitor manufactured using this electrolyte is compared with the conventional electric double-layer capacitor. In addition, the electrolyte cation component of the non-aqueous electrolyte is a strong alkali component that is generated on the surface of the cathode-side polarizable electrode or the surface of the extraction lead connected to the cathode-side polarizable electrode. Order to eliminate the ions, without that lowering of the sealing performance of the sealing member by strong alkali components, thereby is capable to reliably prevent leakage of alkaline electrolyte.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a measurement result of a potential window of an electrolytic solution by cyclic voltammetry using the electrolytic solution according to the first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a measurement result of a potential window of an electrolyte by cyclic voltammetry using the electrolyte of Conventional Example 1.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Hideki Shimamoto, Inventor 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Yukiya Kobayashi 11-11, Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto, Kyoto (72) Inventor Tomoji Nakano 1-11, Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto, Kyoto Prefecture Inside (72) Inventor Kazushi Shiono 1-11, Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto, Kyoto Inside Industrial Co., Ltd. (72) Inventor Hideo Seike 11 Sanyo Kasei Kogyo Co., Ltd.

Claims (7)

[Claims] 1. A polarizable electrode and a non-aqueous electrolytic solution impregnated in the polarizable electrode, wherein the non-aqueous electrolytic solution is represented by a chemical formula (1) or (2) as a polar aprotic solvent. An electric double-layer capacitor formed by dissolving a salt having a compound as a cation component as an electrolyte. Embedded image Embedded image 2. The electric double layer capacitor according to claim 1, wherein the carbon material used for the polarizable electrode is made of one or a mixture of two or more of activated carbon, graphite, and polyacene organic semiconductor. 3. The method according to claim 1, wherein the water contained in the non-aqueous electrolyte is 3,000.
The electric double layer capacitor according to claim 1, wherein the content is not more than ppm. 4. The electrolytic solution according to claim 1, wherein a salt of the electrolyte cation component in which the cation component represented by the formula (1) is (formula 3) is dissolved in a polar aprotic solvent. An electric double layer capacitor according to any one of the above. Embedded image 5. The electrolytic solution according to claim 1, wherein a salt of the electrolyte cation component wherein the cation component represented by the chemical formula (1) is (chemical formula 4) is dissolved in a polar aprotic solvent. An electric double layer capacitor according to any one of the above. Embedded image 6. The electrolytic solution according to claim 1, wherein a salt of the electrolyte cation component in which the cation component represented by the chemical formula (1) is (chemical formula 5) is dissolved in a polar aprotic solvent. An electric double layer capacitor according to any one of the above. Embedded image 7. The method according to claim 1, wherein the cation component represented by the chemical formula 1 is 1-
The electric double layer capacitor according to any one of claims 1 to 3, wherein the electrolytic solution is methyl-3-ethylimidazolium, and an electrolytic solution obtained by dissolving a salt of the electrolyte cation component in a polar aprotic solvent is used.