JPH08227827A - Aluminum electrolytic capacitor and aluminum-electrolytic-capacitor driving electrolyte - Google Patents

Abstract

PURPOSE: To prevent an increase of pH in an electrolyte and the generation of strong alkali even if a voltage is applied by using an aprotic solvent as the main solvent, and using the imidazole salt of carboxylic acid expressed by a specified constitutional formula as the solute. CONSTITUTION: An aprotic solvent such as β-butyrolactone and γ-valerolactone is made to be the main solvent. Then, the imidazole salt of the carboxylic acid indicated by a constitutional formula (In the formula, X indicates aromatic carboxylic acid, aliphatic saturated dicarboxylic acid or aliphatic unsaturated dicarboxylic acid, and R indicates the substituent. The number of carbon in R is made to be 1-3.) is made to be the solute. Att this time, the content of the imidazole salt of the carboxylic acid is made to be about 1-60wt.%. In this way, even if a voltage is applied, an electrolyte which does not generate strong alkali is obtained, and the electrolyte does not leak to the outside from the through hole part of the rubber hole-sealing body on the side of a cathode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor driving electrolytic solution and an aluminum electrolytic capacitor using the electrolytic capacitor driving electrolytic solution.

[0002]

2. Description of the Related Art In an aluminum electrolytic capacitor, a capacitor element in which an anode foil and a cathode foil each having an oxide film formed on the surface thereof are wound with a separator interposed therebetween is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is sealed. Together with this, it has a structure incorporated in the outer case. The lead wires fixed to the anode foil and the cathode foil are drawn out to the outside through the sealing body.

An aluminum electrolytic capacitor having such a structure (hereinafter referred to as "electrolytic capacitor") is
The oxide film formed on the surface of the electrode foil is used as a dielectric. The electrolytic solution for driving the electrolytic capacitor (hereinafter, referred to as “electrolytic solution”) is in contact with the oxide film formed on the surface of the anode foil of this electrolytic capacitor and functions as a true cathode. Furthermore, an electrolytic capacitor having a structure in which an oxide film is used as a dielectric always restores the oxide film by a chemical reaction with an electrolytic solution during energization to stabilize the capacitor characteristics. Therefore, in order to improve the characteristics of the electrolytic capacitor, the electrolytic solution is required to have high electric conductivity and excellent oxide film repair ability. In addition to the above characteristics, the electrolytic solution is required to have long-term reliability under high temperature use.

In order to improve the characteristics of an electrolytic capacitor, conventionally, an electrolytic solution in which a carboxylic acid or a salt thereof is dissolved using an aprotic solvent as a main solvent is often used. Recently, an electrolyte containing a quaternary ammonium salt of carboxylic acid as a solute is often used because of its excellent electrical conductivity, excellent oxide film repair ability, and long-term reliability at high temperatures. ing.

For example, Japanese Patent Laid-Open No. 62-145715 discloses an electrolytic solution containing γ-butyrolactone as a main solvent and a quaternary ammonium salt of an aromatic carboxylic acid as a solute. An electrolytic solution containing a quaternary ammonium salt of an aromatic carboxylic acid as a solute is often used particularly in low voltage electrolytic capacitors.

[0006]

However, for example, an electrolytic solution containing a quaternary ammonium salt such as the above-mentioned quaternary ammonium salt of an aromatic carboxylic acid as a solute is
When a voltage is applied, there is a problem that the pH of the electrolytic solution rises and a strong alkali is generated. For this reason, conventionally, when a voltage was applied to an electrolytic capacitor using an electrolytic solution containing a quaternary ammonium salt as a solute, strong alkali was generated in the electrolytic solution near the tab terminal on the cathode side. The strong alkaline electrolyte corrodes the tab terminal on the cathode side of the electrolytic capacitor to which a voltage is applied, and further swells the through hole of the rubber sealing body fitted to the tab terminal on the cathode side.
Therefore, there is a problem that the fitting between the through hole formed in the rubber sealing body on the cathode side and the tab terminal is weakened, and the electrolytic solution easily leaks to the outside from between the rubber sealing body and the tab terminal. .

In order to solve this problem, various electrolytic solutions have been proposed, such as an electrolytic solution in which a tertiary ammonium salt of carboxylic acid is used as a solute instead of the quaternary ammonium salt. However, in the present situation, the characteristics of the electrolytic solution such as electric conductivity and long-term reliability are inferior to those of the electrolytic solution using a quaternary ammonium salt as a solute.

Various studies have been made to use an electrolytic solution containing a quaternary ammonium salt as a solute in a small-sized electrolytic capacitor having a thin rubber sealing body. For example, a chemical conversion film is formed on the surface of the tab terminal on the cathode side to improve the corrosion resistance to strong alkali, and rubber with excellent corrosion resistance to strong alkali is adopted for the sealing body, but Not completely resolved.

[0009]

The present invention has been made in view of the above-mentioned conventional problems, and as a result of various experiments and studies conducted by the present inventors, an imidazole salt capable of overcoming the above-mentioned problems. Invented an electrolytic solution containing a solute as a solute.

A feature of the electrolytic solution according to the present invention is that an imidazole salt of a carboxylic acid represented by the structural formula [1] shown below is preferably solute, preferably using an aprotic solvent as a main solvent. Further features of the electrolytic capacitor according to the present invention are:
It is preferable to use an electrolytic solution containing an aprotic solvent as a main solvent and an imidazole salt of a carboxylic acid represented by the following structural formula [1] as a solute.

[0011]

[Chemical 13]

(In the formula, X represents an aromatic carboxylic acid, an aliphatic saturated dicarboxylic acid or an aliphatic unsaturated dicarboxylic acid, and R represents a substituent. R has a carbon number of 1 to 3.)

Specific examples of aromatic carboxylic acids include phthalic acid, benzoic acid, salicylic acid and resorcylic acid.

A typical example of the imidazole salt of an aromatic carboxylic acid represented by the structural formula [1] is phthalic acid N.
-Methylimidazole salt, benzoic acid N-methylimidazole salt, salicylic acid N-methylimidazole salt, resorcylic acid N-methylimidazole salt,

N-ethylimidazole phthalate, N-ethylimidazole benzoate, N-ethylimidazole salicylate, N-ethylimidazole resorcylate,

Examples thereof include N-propylimidazole phthalate, N-propylimidazole benzoate, N-propylimidazole salicylate and N-propylimidazole resorcylate.

Further, since the N-methylimidazole phthalate salt of the structural formula [2] shown in the following Chemical Formula 14 can be easily synthesized and produced, it is particularly preferable to use it as a solute of the electrolytic solution according to the present invention. .

[0018]

Embedded image

Specific examples of the aliphatic saturated dicarboxylic acid represented by the structural formula [1] according to the present invention include malonic acid, succinic acid,
Glutaric acid, adipic acid, pimelic acid, cork acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, tetradecanedioic acid, pentadecanedioic acid, tapsinic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid. Examples thereof include acid, eicosane diacid, and docosane diacid.

A typical example of the imidazole salt of the aliphatic saturated dicarboxylic acid represented by the structural formula [1] is malonic acid N.
-Methyl imidazole salt, succinic acid N-methyl imidazole salt, glutaric acid N-methyl imidazole salt, adipic acid N-methyl imidazole salt,

Malonic acid N-ethylimidazole salt, succinic acid N-ethylimidazole salt, glutaric acid N-ethylimidazole salt, adipic acid N-ethylimidazole salt,

Malonic acid N-propylimidazole salt, succinic acid N-propylimidazole salt, glutaric acid N-propylimidazole salt, adipic acid N-propylimidazole salt and the like can be mentioned.

Furthermore, malonic acid N-methylimidazole salt of structural formula [3] shown below in Chemical formula 15 or N-methylimidazole salt of succinic acid of structural formula [4] shown in Chemical formula 16 below can be easily synthesized. It is particularly preferable to use as a solute of the electrolytic solution according to the present invention because it can be produced by

[0024]

[Chemical 15]

[0025]

Embedded image

Further, specific examples of the aliphatic unsaturated dicarboxylic acid represented by the structural formula [1] according to the present invention include maleic acid, citraconic acid, fumaric acid, itaconic acid, glutaconic acid, allylmalonic acid, teraconic acid, mesaconic acid or mucon. Acid, etc.

Representative examples of the imidazole salt of an aliphatic unsaturated dicarboxylic acid include maleic acid N-methylimidazole salt, citraconic acid N-methylimidazole salt, fumaric acid N-methylimidazole salt, and itaconic acid N.
-Methylimidazole salt,

Maleic acid N-ethyl imidazole salt, citraconic acid N-ethyl imidazole salt, fumaric acid N-ethyl imidazole salt, itaconic acid N-ethyl imidazole salt,

Maleic acid N-propylimidazole salt,
Citraconic acid N-propylimidazole salt, fumaric acid N
-Propyl imidazole salt, itaconic acid N-propyl imidazole salt and the like.

Further, the maleic acid N-methylimidazole salt of the structural formula [5] shown below or the citraconic acid N-methylimidazole salt of the structural formula [6] shown below can be easily synthesized. It is particularly preferable to use as a solute of the electrolytic solution according to the present invention because it can be produced by

[0031]

[Chemical 17]

[0032]

Embedded image

In the electrolytic solution according to the present invention, the content of the imidazole salt of the carboxylic acid represented by the structural formula [1] in the electrolytic solution can be variously selected, but if the content is less than 1% by weight, the electrolysis is performed. Insufficient liquid properties. In addition, structural formula [1]
When the content of the carboxylic acid imidazole salt represented by the formula 1 in the electrolytic solution exceeds 60% by weight, the carboxylic acid imidazole salt represented by the structural formula [1] becomes difficult to dissolve. Therefore, the content of the imidazole salt of the carboxylic acid represented by the structural formula [1] is preferably 1% by weight to 60% by weight in the electrolytic solution. Furthermore, the state of a saturated solution is suitable because it has the highest electric conductivity. However, if the content of the imidazole salt of the carboxylic acid represented by the structural formula [1] in the electrolytic solution exceeds 40% by weight, the imidazole salt of the carboxylic acid represented by the structural formula [1] easily precipitates at low temperature. Therefore, it is more preferably 10% by weight to 40% by weight.

As the aprotic solvent used as a solvent in the electrolytic solution according to the present invention, β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone,
γ-caprolactone, ε-caprolactone, γ-heptalactone, γ-hydroxy-n-caprylic acid lactone,
Examples thereof include lactones such as γ-nonalactone, δ-nonalactone, δ-decalactone, and γ-undecalactone. These lactones are preferably used alone or in combination as a solvent. It is particularly preferable to use γ-butyrolactone because it is inexpensive and preferable. The aprotic solvent used in the present invention is not limited to lactones.

In the present invention, the aprotic solvent may be used alone, but the aprotic solvent may be mixed with another solvent. In this case, the solvent to be mixed is preferably glycols. When glycols are mixed with an aprotic solvent, higher electric conductivity is easily obtained than when the aprotic solvent alone dissolves the imidazole salt represented by the structural formula [1] according to the present invention. Examples of glycols mixed with an aprotic solvent include ethylene glycol, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, propylene glycol, diethylene glycol, diethylene glycol monoalkyl ether, diethylene glycol dialkyl ether, polyethylene glycol and glycerin.
These glycols are preferably used alone as a main solvent by mixing with an aprotic solvent, or by mixing these glycols with an aprotic solvent as a main solvent. Furthermore, it is particularly preferable to use ethylene glycol mixed with an aprotic solvent because it is inexpensive. The solvent mixed in the present invention is not limited to glycols.

In the electrolytic solution according to the present invention, the mixing ratio of the lactones and the glycols is preferably 95: 5 to 70:30 by weight, in view of the characteristics of the electrolytic solution.

Therefore, in the present invention, lactones and glycols are mixed as a main solvent, and the above-mentioned structural formula [2] is added thereto.
Having N-methylimidazole phthalate having the formula, or N-methylimidazole malonic acid having the formula [3], or N-methylimidazole succinate having the formula [4], or having the formula [5] More preferably, maleic acid N-methylimidazole salt or citraconic acid N-methylimidazole salt having the structural formula [6] is dissolved to obtain an electrolytic solution.

From the above, in the electrolytic capacitor according to the present invention, lactones and glycols are mixed as a main solvent, and N-methylimidazole phthalate having the structural formula [2] or the structural formula [3] ] With malonic acid N
-Methylimidazole salt, or N-methylimidazole succinate having the structural formula [4], or N-methylimidazole maleic acid salt having the structural formula [5],
Alternatively, it is more preferable to dissolve the citraconic acid N-methylimidazole salt having the structural formula [6] and use it as an electrolytic solution.

In the electrolytic solution according to the present invention, an inorganic acid may be added to the electrolytic solution in order to improve electrolytic solution characteristics such as the ability of the electrolytic solution according to the present invention to repair an oxide film. Furthermore, an inorganic acid salt may be added to the electrolytic solution in order to improve the characteristics of the electrolytic solution. Further, an inorganic acid and an inorganic acid salt may be mixed and added to the electrolytic solution.

The kind of inorganic acid and inorganic acid salt to be added and the amount added to the electrolytic solution are 0.1% by weight to 10% by weight of boric acid, preferably 0.1% to 5% by weight, and 0.1% by weight of borate. % ~
10% by weight, preferably 0.1% to 5% by weight, phosphoric acid 0.1% to 10% by weight, preferably 0.1% by weight
~ 5 wt% and phosphate 0.1 wt% -10 wt%,
It is preferably 0.1% by weight to 5% by weight.

In addition, like the above-mentioned inorganic acid and inorganic acid salt, a polysaccharide such as mannitol or sorbit may be added to improve the characteristics of the electrolytic solution such as the ability of the electrolytic solution according to the present invention to repair the oxide film. . Further, the polysaccharide may be mixed with an inorganic acid or an inorganic acid salt and added to the electrolytic solution. The amount of the polysaccharide added to the electrolytic solution is 0.1% by weight to 10% by weight, respectively.
It is preferably 0.1% by weight to 5% by weight.

Further, a nitro compound or the like may be added as a gas absorbent in an amount of 0.1% by weight to 10% by weight, preferably 0.1% by weight to 5% by weight.

Further, in order to improve the tangent (tan δ) of the initial loss angle of the electrolytic capacitor, the electrolytic solution according to the present invention contains ketones in an amount of 0.1% by weight to 10% by weight, preferably 0.1% by weight. ~ 5 wt% may be added.

The pH of the electrolytic solution according to the present invention is adjusted to pH 4 to pH 1 by adding a desired pH adjusting agent as needed.
2, preferably adjusted to pH 5 to pH 7. Further, the presence of water in the electrolytic solution causes corrosion of the aluminum foil and the like. Therefore, it is more preferable that the water does not exist, but if it is about 5% by weight or less, no particular inconvenience occurs.

[0045]

EXAMPLES First, the composition of the electrolytic solution using the carboxylic acid imidazole salt according to the present invention will be described together with comparative examples.
For Comparative Examples 1 and 2 and Examples 1 and 2, electric conductivity (μS / cm; liquid temperature 40 ° C.) and spark generation voltage (V; liquid temperature 85 ° C.) were measured.

<Comparative Example 1>

Electrolyte composition: tetramethylammonium phthalate 24% by weight γ-butyrolactone 59% by weight ethylene glycol 15% by weight water 2% by weight Electric conductivity 8000 μS / cm, spark generation voltage 55
It was V.

<Comparative Example 2>

Electrolyte composition: Tetramethylammonium citraconic acid 24% by weight γ-butyrolactone 65% by weight Ethylene glycol 10% by weight Water 1% by weight Electrical conductivity 10000 μS / cm, spark generation voltage 8
It was 0V.

<Comparative Example 3>

Electrolyte composition: tetraethylammonium phthalate 20% by weight γ-butyrolactone 60% by weight diethylene glycol 20% by weight

<Comparative Example 4>

Electrolyte composition: tetramethylammonium maleate 20% by weight γ-butyrolactone 79% by weight p-nitrobenzoic acid 1% by weight

<Example 1>

Electrolyte composition: N-methylimidazole phthalate 24% by weight γ-butyrolactone 59% by weight Ethylene glycol 15% by weight Water 2% by weight Electrical conductivity 10000 μS / cm, spark generation voltage 1
It was 12V.

<Example 2>

Electrolyte composition: N-methylimidazole citraconic acid 24% by weight γ-butyrolactone 65% by weight Ethylene glycol 10% by weight Water 1% by weight Electrical conductivity 12000 μS / cm, spark generation voltage 1
It was 15V.

<Example 3>

Electrolyte composition: N-ethylimidazole phthalate 25% by weight γ-butyrolactone 60% by weight Diethylene glycol 15% by weight

<Example 4>

Electrolyte solution composition: N-propylimidazole phthalate 20% by weight γ-butyrolactone 60% by weight Ethylene glycol 10% by weight Propylene glycol 10% by weight

<Example 5>

Electrolyte composition: N-ethylimidazole malonate 20% by weight γ-butyrolactone 60% by weight Ethylene glycol 20% by weight

<Example 6>

Electrolyte composition: N-propylimidazole adipate 20% by weight γ-butyrolactone 69% by weight Ethylene glycol 10% by weight Mannit 1% by weight

Next, the electrolytic solutions of Comparative Examples 1 and 2 and Example 1,
Fifty electrolytic capacitors each having a rated voltage of 6.3 V and 120 μF (product size; diameter of 6.3 mm, axial length of 5 mm) were produced using the electrolytic solution of No. 2. Next, a load test was conducted for 2000 hours in an atmosphere of a temperature of 85 ° C. and a humidity of 85% while applying a rated voltage of 6.3 V to the produced electrolytic capacitor. After the test, an electrolyte leakage test of the electrolytic capacitor was visually inspected. Table 1 shows the electric conductivity and spark generation voltage of the electrolytic solution and the number of leaked liquids of the electrolytic capacitor.

[0067]

[Table 1]

When the electric conductivity of the electrolytic solutions of Comparative Examples 1 and 2 and the electrolytic solutions of Examples 1 and 2 are compared, the electrolytic solutions of the Examples are significantly higher. Further, comparing the spark generation voltage of the electrolytic solutions of Comparative Examples 1 and 2 with the spark generation voltage of the electrolytic solutions of Examples 1 and 2, the electrolytic solutions of Examples 1 and 2 are compared with the electrolytic solutions of Comparative Examples 1 and 2. Spark generation voltage is extremely high and excellent. Further, when comparing the number of electrolyte leaks generated after the load test of the produced electrolytic capacitors, all electrolyte leaks occurred in Comparative Examples 1 and 2, whereas the electrolytic capacitors of Examples 1 and 2 leak electrolyte. It can be seen that there is no occurrence of.

Next, Comparative Examples 1 to 4 and Example 1
~ Rated voltage 25V 10μ using the electrolyte according to Example 6
F (product size; diameter 5 mm, shaft length 5 mm) electrolytic capacitors of 50 each were manufactured, and the capacitance (μF), loss tangent (tan δ) and leakage current (1 minute value; μA) were measured. After that, a load test was performed by exposing the produced electrolytic capacitor to an atmosphere having a temperature of 85 ° C. and a humidity of 85% for 2000 hours while applying a rated voltage of 25V.

Capacitance (μF), loss angle tangent (tan δ) and leakage current (1 minute) of each electrolytic capacitor prepared using the electrolytic solution according to Comparative Examples 1 to 4 and Examples 1 to 6 Table 2 shows the average value of the values; μA) and the results of visual inspection of the electrolyte leakage state to the outside of the electrolytic capacitor after the load test.

[0071]

[Table 2]

The electrolytic capacitors of Examples 1 to 6 are superior to the electrolytic capacitors of Comparative Examples 1 to 4 in tangent of loss angle (tan δ) and leakage current (1 minute value; μA). I understand. Further, in each of the electrolytic capacitors of Comparative Examples 1 to 4, liquid leakage has occurred, the tab terminals on the cathode side of the electrolytic capacitors are corroded, and the through holes of the rubber sealing body to be fitted are swollen. It was confirmed. On the other hand, no leakage of the electrolytic capacitors of Examples 1 to 6 was observed, and no corrosion of the tab terminal on the cathode side of the electrolytic capacitor and no swelling of the through hole of the rubber sealing body to be fitted. It was Therefore, it is understood that the electrolytic solution using the imidazole salt of carboxylic acid represented by the structural formula [1] according to the present invention does not generate a strong alkali.

From the above, the structural formula [1] according to the present invention
It can be seen that the electrolytic solution using the imidazole salt of carboxylic acid shown in 1) has excellent electrolytic solution characteristics and long-term reliability as compared with the electrolytic solution using the conventional quaternary ammonium salt.

[0074]

As described above, by using the imidazole salt of carboxylic acid represented by the structural formula [1] as the solute, it is possible to obtain an electrolytic solution in which a strong alkali is not generated even when a voltage is applied. Therefore, the electrolytic solution does not leak to the outside from the through-hole of the rubber sealing body fitted to the tab terminal on the cathode side of the electrolytic capacitor, which is longer than the conventional electrolytic capacitor using a quaternary ammonium salt as a solute. It is possible to obtain an electrolytic capacitor having extremely excellent reliability.

Claims (12)

[Claims] 1. An electrolytic solution for driving an aluminum electrolytic capacitor, wherein an imidazole salt of a carboxylic acid represented by the following structural formula [1] is used as a solute. Embedded image (In the formula, X represents an aromatic carboxylic acid, an aliphatic saturated dicarboxylic acid or an aliphatic unsaturated dicarboxylic acid, and R represents a substituent. The carbon number of R is 1 to 3.) 2. An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that a solute is an N-methylimidazole phthalate represented by the following structural formula [2]. Embedded image 3. Malonic acid N- represented by the following structural formula [3]:
An electrolytic solution for driving an aluminum electrolytic capacitor, which is characterized by using a methyl imidazole salt as a solute. Embedded image 4. A succinic acid N- represented by the following structural formula [4]:
An electrolytic solution for driving an aluminum electrolytic capacitor, which is characterized by using a methyl imidazole salt as a solute. [Chemical 4] 5. A maleic acid N represented by the following structural formula [5]:
An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that a methyl imidazole salt is used as a solute. Embedded image 6. An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that an N-methylimidazole citraconic acid salt represented by the following structural formula [6] is used as a solute. [Chemical 6] 7. A structure in which a capacitor element formed by winding an aluminum anode foil and an aluminum cathode foil via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated into an outer case together with a sealing body. An aluminum electrolytic capacitor, characterized in that, in the electrolytic capacitor, an electrolytic capacitor driving electrolytic solution in which an imidazole salt of a carboxylic acid represented by the following structural formula [1] is dissolved is used as a solvent. [Chemical 7] (In the formula, X represents an aromatic carboxylic acid, an aliphatic saturated dicarboxylic acid or an aliphatic unsaturated dicarboxylic acid, and R represents a substituent. The carbon number of R is 1 to 3.) 8. A structure in which a capacitor element in which an aluminum anode foil and an aluminum cathode foil are wound via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated in an outer case together with a sealing body. An aluminum electrolytic capacitor, characterized in that, in the electrolytic capacitor, an electrolytic capacitor driving electrolytic solution in which a N-methylimidazole phthalate salt represented by the following structural formula [2] is dissolved is used as a solvent. Embedded image 9. A structure in which a capacitor element in which an aluminum anode foil and an aluminum cathode foil are wound via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated into an outer case together with a sealing body. In the electrolytic capacitor, an aluminum electrolytic capacitor characterized by using, as a solvent, an electrolytic capacitor driving electrolytic solution in which a malonic acid N-methylimidazole salt represented by the following structural formula [3] is dissolved. [Chemical 9] 10. A structure in which a capacitor element formed by winding an aluminum anode foil and an aluminum cathode foil via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated in an outer case together with a sealing body. An aluminum electrolytic capacitor, characterized in that, in the electrolytic capacitor, an electrolytic capacitor driving electrolytic solution in which a N-methylimidazole succinate salt represented by the following structural formula [4] is dissolved is used as a solvent. [Chemical 10] 11. A structure in which a capacitor element in which an aluminum anode foil and an aluminum cathode foil are wound via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated into an outer case together with a sealing body. In the electrolytic capacitor, an aluminum electrolytic capacitor characterized by using an electrolytic capacitor driving electrolytic solution in which a maleic acid N-methylimidazole salt represented by the following structural formula [5] is dissolved is used as a solvent. [Chemical 11] 12. A structure in which a capacitor element formed by winding an aluminum anode foil and an aluminum cathode foil via a separator is impregnated with an electrolytic solution for driving an electrolytic capacitor, and the capacitor element is incorporated in an outer case together with a sealing body. An aluminum electrolytic capacitor, characterized in that, in the electrolytic capacitor, an electrolytic capacitor driving electrolytic solution in which a citraconic acid N-methylimidazole salt represented by the following structural formula [6] is dissolved is used as a solvent. [Chemical 12]