JP2001102266A - Electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which has low impedance characteristic can be used in 100V specification, and high reliability at 125 deg.C. SOLUTION: An electrolyte where a quaternary cyclic amidium salt of benzoic acid is dissolved in a mixed solvent of γ-butyrolactone and ethylene glycol, and colloidal silica, alkyl phosphoric acid having a 3-8C alkyl group and oxidizing agent are added is used as electrolyte of an electrolytic capacitor. A coating film composed of metal nitride or metal is formed on the surface of a cathode electrode foil, and an insulating film constituted of an anodic oxidation coating film layer is formed on the surface of a cathode lead-out means, so that an electrolytic capacitor which has low impedance characteristic, stability of breakdown voltage characteristic or the like at 125 deg.C and satisfactory liquid leakage characteristic and can be used in 100V specification can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor, in particular, having a low impedance characteristic and capable of 100V specification.
Further, the present invention relates to an electrolytic capacitor having high reliability at 125 ° C.

[0002]

2. Description of the Related Art An electrolytic capacitor generally has a structure as shown in FIG. That is, the strip-like high-purity aluminum foil is chemically or electrochemically etched to enlarge the aluminum foil surface, and the aluminum foil is subjected to a chemical conversion treatment in a chemical conversion solution such as an ammonium borate aqueous solution. An anode electrode foil 2 having an oxide film layer formed on the surface thereof and a cathode electrode foil 3 made of a high-purity aluminum foil subjected to only an etching treatment are wound through a separator 11 made of manila paper or the like to form a capacitor. An element 1 is formed. And this capacitor element 1
Is impregnated with an electrolytic solution for driving an electrolytic capacitor, and then stored in a bottomed cylindrical outer case 10 made of aluminum or the like. A sealing body 9 made of elastic rubber is attached to the opening of the outer case 10, and the outer case 10 is sealed by drawing.

As shown in FIG. 2, lead wires 4 and 5 serving as electrode lead-out means for pulling out electrodes of both electrodes are provided on the anode electrode foil 2 and the cathode electrode foil 3 by stitching, ultrasonic welding or the like. Connected by means. Each of the lead wires 4 and 5 as the electrode lead-out means comprises a round bar portion 6 made of aluminum and a connecting portion 7 in contact with the bipolar electrode foils 2 and 3. An external connection portion 8 made of a possible metal is fixed by means such as welding.

[0004]

In recent years, there has been an increasing demand for the use of electrolytic capacitors in the fields of vehicles and exchanges. In the on-vehicle field, it is a high-temperature specification, and in the exchange field, it is a long-life specification. In both cases, high reliability at 125 ° C. is required. In this field, low impedance characteristics and 100 V specification must be satisfied.

Conventionally, as an electrolytic solution of 100 V and 125 ° C. specification, an electrolytic solution using ethylene glycol as a solvent and ammonium benzoate as a solute has been used. I do not endure. In addition, as the conventional electrolytic solution for electrolytic capacitors having low impedance characteristics, γ-butyrolactone is used as a solvent, and an electrolytic solution using a phthalate or maleate of a quaternized cyclic amidinium as a solute is used. Withstand voltage is low and cannot meet 100V specification. Therefore, using γ-butyrolactone as a main solvent and using a quaternized cyclic amidinium salt of benzoic acid as a solute,
By adding silica particles or a phosphoric acid compound, which is known to have a withstand voltage improving effect, a withstand voltage characteristic of 100 V can be obtained. However, this electrolyte has problems such as a decrease in withstand voltage during a life test and the occurrence of leakage, and cannot satisfy high reliability at 125 ° C. In particular, in the electrolytic solution using a quaternized cyclic amidinium salt, there is a problem that leakage occurs, but with an electrolyte using γ-butyrolactone as a solvent and a quaternized cyclic amidinium salt of benzoic acid as a solute, This liquid leakage characteristic tends to deteriorate. As described above, in reality, it has not been possible to obtain an electrolytic capacitor that can satisfy the above-mentioned requirements.

Therefore, the present invention is intended to improve this drawback, has a low impedance characteristic, is capable of 100 V specification, and has a stability such as a withstand voltage characteristic at 125 ° C. and a good liquid leakage characteristic. An object of the present invention is to provide an electrolytic capacitor having high reliability characteristics.

[0007]

An electrolytic capacitor according to the present invention comprises an anode electrode foil provided with an anode lead-out means, and a cathode lead-out means provided with an insulating layer on a part or all of the surface, and a part of the surface. A cathode electrode foil, on which a film made of metal nitride or metal is entirely formed, is wound through a separator to form a capacitor element, and a benzoic acid mixed solvent of γ-butyrolactone and ethylene glycol is formed on the capacitor element. Dissolving the quaternized cyclic amidinium salt,
It is characterized in that it is impregnated with an electrolytic solution obtained by adding colloidal silica, an alkyl phosphoric acid represented by the following chemical formula (2), and an oxidizing agent and stored in an outer case.

Embedded image

The insulating layer formed on part or all of the surface of the cathode lead-out means is formed of an anodic oxide film layer made of aluminum oxide, and is a metal nitride covering part or all of the surface of the cathode electrode foil. Examples of the metal include titanium nitride, zirconium nitride, tantalum nitride, and niobium nitride, and examples of the metal include titanium, zirconium, tantalum, and niobium. As the oxidizing agent added to the electrolyte,
Nitro compounds can be used. Further, the cathode extraction means includes a round bar portion made of aluminum and a flat connection portion, and the insulating layer covers at least substantially the entire surface of the round bar portion. It is further preferable that the anode extraction means includes a round bar portion made of aluminum and a flat connection portion, and the insulating layer made of aluminum oxide covers at least substantially the entire surface of the round bar portion. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an aluminum electrolytic capacitor has the same structure as that of the prior art, as shown in FIGS. The capacitor element 1 is formed by winding an anode electrode foil 2 and a cathode electrode foil 3 with a separator 8 interposed therebetween. FIG. 2
As shown in FIG. 3, lead wires 4 and 5, which are an anode extracting means and a cathode extracting means, are connected to the anode electrode foil 2 and the cathode electrode foil 3, respectively. These leads 4,
The lead wire 5 includes a connecting portion 7 connected to each foil, a round bar portion 6 continuous with the connecting portion 7, and an external connecting portion 8 welded to the round bar portion 6. The respective foils and lead wires are mechanically connected by a stitch method, ultrasonic welding, or the like.

The anode electrode foil 2 is formed by chemically or electrochemically etching an aluminum foil having a purity of 99% or more in an acidic solution and expanding the surface thereof, and then forming the aluminum foil in an aqueous solution of ammonium borate or ammonium adipate. After the treatment, an anodic oxide film layer is formed on the surface.

Further, as the cathode electrode foil 3, an aluminum foil having a purity of 99% or more is etched similarly to the anode electrode foil 2. Then, a film made of metal nitride or metal is formed on part or all of the surface of the cathode electrode foil 3. Examples of the metal nitride include titanium nitride, zirconium nitride, tantalum nitride, and niobium nitride. Examples of the metal include titanium, zirconium, tantalum, and niobium. Further, an insulating layer is formed on part or all of the surface of the lead wire 5. Examples of the insulating layer include an anodic oxide film made of aluminum oxide obtained by a chemical conversion treatment using an aqueous solution of ammonium borate, an aqueous solution of ammonium phosphate, or an aqueous solution of ammonium adipate. Furthermore, at least the lead wire 5
It is preferable that almost the entire surface of the round bar portion 6 is covered. It is more preferable that the lead wire 4 includes an insulating layer similar to the lead wire 5.

The capacitor element 1 configured as described above
Is impregnated with an electrolytic solution for driving an electrolytic capacitor. An electrolytic solution obtained by using a mixed solvent of γ-butyrolactone and ethylene glycol as an electrolytic solution, dissolving a quaternized cyclic amidinium salt of benzoic acid, and adding colloidal silica, an alkyl phosphoric acid represented by Chemical Formula 2, and an oxidizing agent Is used.

As a low-impedance electrolyte using γ-butyrolactone as a solvent, ethylene glycol is used as a secondary solvent in order to obtain a high-pressure specification of 100 V, and the chemical conversion of the electrolyte is improved. The content of ethylene glycol in the mixed solvent is 5 to 50 wt%, preferably 10 to 20 wt%. If the content is less than this range, the leakage current characteristics of the electrolytic capacitor will be reduced, and if it exceeds this range, the impedance characteristics will be reduced.

In this mixed solvent, a quaternized cyclic amidinium salt of benzoic acid is dissolved as a solute. The content of the quaternized cyclic amidinium salt of benzoic acid in the electrolyte is 5 to 30 watts.
When the amount is less than t%, preferably 10 to 20% by weight, the impedance characteristic is deteriorated. When the amount exceeds this range, the withstand voltage characteristic is deteriorated.

The quaternized cyclic amidinium ion serving as the cation component is a cation obtained by quaternizing a cyclic compound having an N, N, N'-substituted amidine group.
Examples of the cyclic compound having an N′-substituted amidine group include the following compounds. Imidazole monocyclic compound (1-
Methylimidazole, 1-phenylimidazole, 1,
2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1,2-dimethylimidazole, 1,2,2
Imidazole homologs such as 4-trimethylimidazole, 1-ethyl-2,3-dimethylimidazole, 1,2,3,4-tetramethylimidazole, 1-methyl-2
Oxyalkyl derivatives such as -oxymethylimidazole and 1-methyl-2-oxyethylimidazole, nitro derivatives such as 1-methyl-4 (5) -nitroimidazole, 1,2-dimethyl-5 (4) -aminoimidazole and the like Aminoderivatives), benzimidazole compounds (1
-Methylbenzimidazole, 1-methyl-2-benzimidazole, 1-methyl-5 (6) -nitrobenzimidazole, etc., compounds having a 2-imidazoline ring (1-methylimidazoline, 1,2-dimethylimidazoline, 1 , 2,4-trimethylimidazoline, 1-methyl-2-phenylimidazoline, 1-ethyl-2-methyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-ethoxymethylimidazoline, etc.), Compound having a tetrahydropyrimidine ring (1
-Methyl-1,4,5,6-tetrahydropyrimidine,
1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1,5-diazabicyclo [4,3,0] nonene-5, and the like. Among them, quaternized amidinium such as 1-ethyl-2,3-dimethylimidazole and 1,2,3,4-tetramethylimidazole is preferred.

Then, colloidal silica and an alkyl phosphoric acid represented by the formula (2) are added. The electrolytic solution having the above configuration has a high conductivity and a withstand voltage characteristic of 100 V. Here, the colloidal silica is dispersed in a dispersion solvent and added as a colloid solution. The alkyl group of the alkyl phosphoric acid represented by Chemical Formula ₂ , R ₁ and R ₂ have 3 to 8 carbon atoms. If it is less than 3, the alkylphosphoric acid is hydrolyzed at high temperatures, and the withstand voltage characteristic is reduced. If it exceeds 8, the impedance characteristic is reduced. Therefore, high reliability at 125 ° C. cannot be obtained with an alkyl phosphoric acid having an alkyl group having less than 3 carbon atoms, such as diethyl phosphate.

The content of colloidal silica in the electrolyte is as follows:
2 to 12 wt%, preferably 4 to 8 wt%, if less than this range, the withstand voltage decreases, and if it exceeds this range, the impedance characteristics deteriorate. The content of the alkyl phosphoric acid in the electrolyte is 1 to 10 wt%, preferably 2 to 6 wt%,
Below this range, the withstand voltage decreases, and beyond this range, both the impedance characteristics and the withstand voltage characteristics decrease.

As the oxidizing agent, nitro compounds such as nitrobenzoic acids, nitroanisole, nitrophenol and nitronaphthol are used. The content of the oxidizing agent in the electrolyte is 0.2 to 5 wt%, preferably,
When the content is 0.5 to 4 wt%, less than this range, the liquid leakage characteristics deteriorate, and when it exceeds this range, the impedance characteristics deteriorate.

The capacitor element 1 impregnated with the electrolytic solution as described above is housed in an outer case 10 made of aluminum having a bottomed cylindrical shape, and lead wires 6 and 7 are led out to the open end of the outer case 10. The sealing of the electrolytic capacitor is performed by inserting a sealing member 9 made of butyl rubber having a hole and crimping the end of the outer case 10.

The above electrolytic capacitor of the present invention has a low impedance characteristic, is capable of 100 V specification,
Good stability such as withstand voltage characteristics at ℃ and good liquid leakage characteristics.

Here, the reason why the liquid leakage property is good in the present invention is considered as follows. In general, the mechanism by which the electrolyte in which the quaternized cyclic amidinium salt is dissolved leaks from the cathode lead portion is considered as follows. That is, in the conventional electrolytic capacitor,
Since the spontaneous immersion potential of the cathode lead 5 shows a more noble potential than the spontaneous immersion potential of the cathode electrode foil 3, when left unloaded, a local battery is constituted by the cathode lead and the cathode electrode foil, The cathode current will flow through the lead wire,
In a DC load state, more cathode current flows through the cathode lead wire than the cathode electrode foil. In this way, in both cases of load and no load, a cathode current flows through the cathode lead wire, and as a result,
A reduction reaction of dissolved oxygen or hydrogen ions occurs on the cathode lead wire side, and hydroxyl ions are generated at the electrolyte interface between the round bar portion 6 and the connection portion 7 of the cathode lead wire.

Then, when the hydroxyl ions are generated in this manner, the quaternized cyclic amidinium is hydrolyzed,
Combines with hydroxyl ions, resulting in secondary amines. Further, when hydroxyl ions are generated and become basic at pH = 7 or more, γ-butyrolactone as a solvent is combined with hydroxyl ions by a hydrolysis reaction to form γ-hydroxybutyric acid. This reduces the hydroxyl ions and the basicity. Thus, when the basicity decreases, the secondary amine generated by the hydrolysis reaction of the quaternized cyclic amidinium becomes the quaternized cyclic amidinium again,
This quaternized cyclic amidinium has no volatility and is highly hygroscopic, so the quaternized cyclic amidinium regenerated between the round bar portion of the cathode lead wire and the sealing member absorbs moisture and becomes a liquid leakage state. Become. The above is inferred from the results of analysis that the liquid leakage is composed of most of water and quaternized cyclic amidinium.

In the case of an electrolytic solution using a quaternized amidinium salt of γ-butyrolactone and benzoic acid, the electrolyte leaks due to the above-mentioned reaction. Further, in this electrolyte, the pH must be increased in order to increase the electric conductivity, and therefore, the concentration of hydroxide ions in the electrolyte is increased, and the amount of the quaternized cyclic amidinium regenerated as a whole is increased. It seems that the leaked state became worse and the liquid leakage state became worse.

However, according to the present invention, a film made of metal nitride is formed on the surface of the cathode electrode foil, and an insulating layer made of an anodic oxide film is formed on the surface of the cathode lead-out means. Then, a current flows through the cathode electrode foil to cause a reduction reaction of dissolved oxygen or hydrogen ions on the cathode electrode foil, and an oxidizing agent added to the electrolyte accelerates the reduction reaction. Moreover, the cathode electrode foil has a large active surface area because it has been etched and expanded. Then, the insulating layer formed on the surface of the cathode extraction means further suppresses the current flowing through the cathode extraction means. Therefore, most of the cathode current flows through the cathode electrode foil, and no current flows through the cathode extraction means, or the current flowing through the cathode extraction means is much smaller than in the past. Similarly, when there is no load, the cathode current flows to the cathode electrode foil.

As described above, according to the configuration of the present invention, the flow of current to the cathode extracting means is suppressed,
The generation of hydroxyl ions near the cathode extraction means is suppressed. Therefore, regeneration of the quaternized cyclic amidinium in the vicinity of the cathode extraction means due to the above-described reaction is suppressed, and the liquid leakage state is suppressed.

Further, when the external connection portion on the anode side and the external connection portion on the cathode side come into contact with each other when no load is left, if the lead wire 4 is made of aluminum or the like which is more noble than the cathode electrode foil, the anode 4 A local battery is constituted by the lead wire 4 on the side and the cathode electrode foil, and a reduction reaction of dissolved oxygen or hydrogen ions occurs near the lead wire 4. As a result, hydroxide ions are generated on the anode side, causing deterioration in sealing accuracy. Therefore, the lead wire 4 includes a round bar portion made of aluminum and a flat connection portion, and the insulating layer made of aluminum oxide covers at least substantially the entire surface of the round bar portion, so that the lead wire 4 is smaller than the cathode electrode foil. It is preferable to be in a low state.

A technique of coating a metal nitride such as titanium nitride on a cathode electrode foil by means such as vapor deposition has been proposed (for example, Japanese Patent Application Laid-Open No. 2-117123,
JP-A-4-61109, JP-A-4-329620
No.). However, these proposals aim at increasing the surface area on the cathode electrode foil side, and do not aim at reversing the potentials of the cathode electrode foil and the cathode extracting means as in the present invention. That is, since the present invention does not intend to increase the surface area, it is not necessary to cover the entire surface of the cathode electrode foil with the metal nitride. For example, it has been confirmed that the same effect can be obtained if only one surface is coated with titanium nitride, or if titanium nitride is coated in a certain ratio of area. In addition, even if only the cathode electrode foil coated with titanium nitride on the surface is used, the current flowing through the lead wire on the cathode side cannot be completely suppressed, and as a result, the liquid is discharged by applying a long-time DC current. I have confirmed that.

For the above reasons, in the present invention, even when γ-butyrolactone is used as a solvent and a quaternized cyclic amidinium salt of benzoic acid is used as a solute,
It is considered that liquid leakage was prevented under both load and no load.

As described above, the quaternized cyclic amidinium salt of benzoic acid is dissolved in the mixed solvent of γ-butyrolactone and ethylene glycol of the present invention, and the colloidal silica and the alkylphosphorus having an alkyl group having 3 to 8 carbon atoms are dissolved. The electrolytic solution to which an acid and an oxidizing agent are added, and the synergistic action of the cathode electrode foil and the cathode extraction means of the present invention, having low impedance characteristics,
An electrolytic capacitor capable of 100V specifications and having good stability such as withstand voltage characteristics at 125 ° C. and excellent liquid leakage characteristics is realized.

[0030]

Next, the present invention will be described with reference to embodiments. Since the structure of the electrolytic capacitor is the same as that of the related art, it will be described with reference to FIGS. The capacitor element 1 is formed by winding an anode electrode foil 2 and a cathode electrode foil 3 with a separator 11 interposed therebetween. As shown in FIG. 2, the anode electrode foil 2 and the cathode electrode foil 3 have a lead wire 4 for leading the anode,
Lead wires 5 for drawing out the cathode are connected to each other.

The lead wires 4, 5 are connected to a connecting portion 7 in contact with the electrode foil, a round bar portion 6 formed integrally with the connecting portion 7, and an external connecting portion 8 fixed to the tip of the round bar portion 6. Become. The connecting portion 7 and the round bar portion 6 are made of 99% aluminum, and the external connecting portion 8 is made of a copper-plated steel wire (hereinafter referred to as a CP wire). An anodic oxide film made of aluminum oxide is formed on at least the surface of the round bar portion 6 of the lead wires 4 and 5 by a chemical conversion treatment with an ammonium phosphate aqueous solution. The lead wires 4 and 5 are electrically connected to the bipolar electrode foils 2 and 3 at the connection portions 7 by means such as stitching and ultrasonic welding.

The anode electrode foil 2 is obtained by chemically or electrochemically etching an aluminum foil having a purity of 99.9% in an acidic solution to expand the surface, and then performing a chemical conversion treatment in an aqueous solution of ammonium adipate. An anodic oxide film layer is formed on the surface.

The cathode electrode foil 3 is obtained by etching an aluminum foil having a purity of 99.9% similarly to the anode electrode foil 2. The entire surface of the cathode electrode foil 3 is coated with titanium nitride or zirconium nitride by a vapor deposition method. In this embodiment, the coating layer made of a metal nitride such as titanium nitride covers the entire surface of the cathode electrode foil 3, but if necessary, a part of the cathode electrode foil 3, for example, the cathode electrode foil 3. Only one surface may be coated with the metal nitride. The thickness of the metal nitride formed here is 0.04 to
0.5 μm.

The capacitor element 1 configured as described above
Is impregnated with an electrolytic solution for driving an electrolytic capacitor. As an electrolyte, benzoic acid (1-ethyl-2,3-dimethylimidazolium) salt (20 wt%) was dissolved as a solute in a mixed solvent of γ-butyrolactone (61 wt%) and ethylene glycol (11 wt%), and colloidal. Silica (5
wt%), dioctyl phosphate (2 wt%), oxidizing agent (1
wt%) was used.

The capacitor element 1 impregnated with the electrolytic solution as described above is housed in an outer case 10 made of aluminum having a bottomed cylindrical shape, and a sealing body 9 is attached to the opening of the outer case 10. Is subjected to a drawing process to seal the outer case 10. The sealing body 9 is made of an elastic rubber such as butyl rubber, for example, and has through holes for leading the lead wires 4 and 5, respectively.

With respect to the electrolytic capacitors according to the embodiment of the present invention configured as described above, and the electrolytic capacitors according to Conventional Examples 1 and 2 and Comparative Examples 1 to 4, the initial characteristics and the temperature at 125 ° C.
The load and no-load characteristics at 00 hours were investigated. Here, ethylene glycol (90 wt.
%), Ammonium benzoate (10 wt%), Conventional Example 2
Γ-butyrolactone (83 wt%),
Maleic acid (10 wt%), triethylamine (7 wt%)
%). In addition, aluminum foil having a purity of 99.9% was used for the cathode electrode foils of the conventional example and the comparative example. And the rating of the electrolytic capacitor is 100W
V-56 μF. The specifications and initial characteristics of these electrolytic capacitors are shown in (Table 1), and the results of 125 ° C. load and no-load tests are shown in (Table 2). Further, in order to investigate the leakage characteristics, a 100 WV-4.7 μF (6.3φ-11 L) electrolytic capacitor was used, and the leakage characteristics are severe conditions.
The state of liquid leakage was determined under conditions of 5 ° C./85% for 3000 hours. The results are shown in (Table 3).

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

As is clear from Table 1, in the embodiment, a capacitor having a low tan δ is obtained. In addition, as is clear from (Table 2) and (Table 3), 125 ° C.
It can be seen that the characteristics after the load and no-load tests are stable, high reliability at 125 ° C. is obtained, and the liquid leakage characteristics are also good. In contrast, in Conventional Example 1, the initial ta
n δ is high, and in Conventional Example 2, tan δ significantly increases in both the 125 ° C. load and no-load tests.

Further, as is apparent from Table 3, the liquid bleeding was suppressed to some extent under both load and no load, as seen in Comparative Example 3 in which a film made of metal nitride was formed on the cathode electrode foil. Although possible, it is difficult to completely suppress them. Also, of the three elements of the present invention, forming a metal nitride film on the cathode electrode foil, adding an oxidizing agent to the electrolytic solution, and forming an insulating layer on the round bar portion of the lead wire, Also in Comparative Examples 1, 2, and 4 in which one element is combined, it is not possible to completely prevent the liquid from flowing out. As described above, the synergistic action of the electrolytic solution, the cathode electrode foil, and the lead wire according to the present invention allows low impedance characteristics and 100 V
It can be seen that the specifications, stability such as withstand voltage characteristics at 125 ° C., and good liquid leakage characteristics are realized.

[0042]

According to the present invention, in an aluminum electrolytic capacitor, a quaternized cyclic amidinium salt of benzoic acid is dissolved in a mixed solvent of γ-butyrolactone and ethylene glycol as an electrolytic solution. Using an electrolytic solution obtained by adding the indicated alkyl phosphoric acid and an oxidizing agent, a film made of metal nitride or metal is formed on the surface of the cathode electrode foil, and an insulating film made of an anodic oxide film layer is formed on the surface of the cathode extraction means. A layer is formed. As described above, the synergistic action of the electrolytic solution of the present invention, the cathode electrode foil, and the cathode extraction means allows low impedance characteristics, 100
Stability such as V specification, withstand voltage characteristics at 125 ° C., and good liquid leakage characteristics can be realized.

[Brief description of the drawings]

FIG. 1 is an internal sectional view showing a structure of an electrolytic capacitor.

FIG. 2 is an exploded perspective view showing the structure of the capacitor element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode electrode foil 3 Cathode electrode foil 4 Lead wire for anode drawing 5 Lead wire for cathode drawing 6 Round bar part 7 Connection part 8 External connection part 9 Sealing body 10 Exterior case 11 Separator

Claims (6)

[Claims] 1. An anode electrode foil provided with anode extraction means,
A cathode electrode foil having a cathode extraction means having an insulating layer formed on part or all of the surface and a cathode electrode foil having a coating made of metal nitride or metal formed on part or all of the surface; An element is formed, and a quaternized cyclic amidinium salt of benzoic acid is dissolved in a mixed solvent of γ-butyrolactone and ethylene glycol in the capacitor element, and colloidal silica, an alkyl phosphoric acid represented by the formula (1), and an oxidizing agent Impregnated with the electrolyte solution
Electrolytic capacitor housed in an outer case. Embedded image (In the formula, R ₁ and R ₂ represent the same or different alkyl groups having 3 to 8 carbon atoms.) 2. The electrolytic capacitor according to claim 1, wherein the insulating layer formed on part or all of the surface of the cathode extraction means is an anodic oxide film layer made of aluminum oxide. 3. The electrolytic capacitor according to claim 1, wherein the metal nitride is titanium nitride, zirconium nitride, tantalum nitride, and niobium nitride, and the metal is titanium, zirconium, tantalum, and niobium. 4. The electrolytic capacitor according to claim 1, wherein the oxidizing agent is a nitro compound. 5. The method according to claim 1, wherein the cathode extracting means comprises:
An electrolytic capacitor including a round bar portion made of aluminum and a flat connecting portion, wherein the insulating layer covers at least substantially the entire surface of the round bar portion. 6. The anode drawing means according to claim 1,
An electrolytic capacitor including a round bar portion made of aluminum and a flat connection portion, wherein an insulating layer made of aluminum oxide covers at least substantially the entire surface of the round bar portion.