JPH05144676A - Electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain an electrolytic capacitor which is composed of polymer electrolyte and has low impedance and long term reliability free from solution leak. CONSTITUTION:A polymer electrolytic layer 6 contains the following; crosslinked body of polymer compound wherein polyether polyol is applied to base structure, and the polyether part is random copolymer of oxyethylene and oxypropylene, electron conducting polymer compound, and specified ammono-salt. A capacitor is constituted by sandwiching the polymer electrolytic layer 6 between an electrode 1 and an electrode 4 which form dielectric on the surfaces. By constituting an electrolytic capacitor by using the above polymer electrolyte, the electrolytic capacitor having low impedance and high in breakdown strength of the coating film can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable electrolytic capacitor using a polymer electrolyte as an electrolytic solution.

[0002]

2. Description of the Related Art Conventionally, a dielectric material made of an oxide such as aluminum oxide and an organic electrolytic solution obtained by dissolving an ammonium salt in a high boiling point organic solvent such as ethylene glycol have been known as constituent materials of this type of electrolytic capacitor. Has been used. However, in a capacitor using such an electrolytic solution, it has been difficult to ensure reliability for a long period of time due to leakage of the electrolytic solution and evaporation and dissipation.

In order to solve such a problem, an ion conductive polymer electrolyte in which an alkali metal salt is dissolved in a polymer matrix made of a mixture of a siloxane-alkylene oxide copolymer and polyethylene oxide instead of the electrolytic solution. Electrolytic capacitor using (Tokuhyo 1-503425)
Is proposed. However, it is extremely important to realize an electrolyte with high electric conductivity by combining a polymer base material with an ammonium salt and an electron-conducting polymer compound.
It is not described in the official gazette.

[0004]

However, in a conventional electrolytic capacitor using such an ion conductive polymer electrolyte having an alkali metal as a mobile ion, alkali metal ions diffuse into a dielectric material forming the electrolytic capacitor. It's easy to do. Therefore, there is a problem that the dielectric constant of the dielectric is lowered, and finally the capacitor is electrically internally short-circuited.

In order to solve such a problem, it is conceivable to use ammonium ions as mobile ions of the electrolyte constituting the electrolytic capacitor. However, it has been conventionally known that an ionic conductive polymer electrolyte having ammonium ions as mobile ions has extremely low ionic conductivity (conductive polymer Naoya Ogata, published by Kodansha Scientific).

Further, the ionic conductivity of the electrolyte that constitutes the electrolytic capacitor contributes to the impedance component of the electrical characteristics of the capacitor, and it becomes difficult to actually use it when the ionic conductivity is small and the impedance component is large.

The present invention solves such a problem, and an object thereof is to provide an electrolytic capacitor having a highly reliable polymer electrolyte which has a high ionic conductivity and does not evaporate or leak. It is what

[0008]

In order to solve this problem, the present invention uses a polyether polyol as a basic skeleton,
A polymer compound having a structure of the chemical formula 2 in which the polyether moiety of the basic skeleton is a random copolymer of oxyethylene and oxypropylene, an electron conductive polymer compound, and an electrolyte mainly composed of an ammonium salt. , A dielectric mainly composed of a metal oxide, and an electrically conductive electrode.

Further, a polymer compound obtained by crosslinking the terminal group of the compound of Chemical formula 2 with a diol compound is used as an electrolyte.

[0010]

[Chemical 2]

Further, as the electron-conductive polymer compound, a polymer compound containing pyrrole, aniline, thiophene or a derivative thereof as a monomer, or a mixture of the polymer compounds is used.

The electron-conducting polymer compound is sulfuric acid,
A compound selected from paratoluenesulfonic acid or ammonium paratoluenesulfonate or a mixture thereof is contained as a dopant.

As ammonium salts, ammonium adipate, ammonium azelate, ammonium benzoate, ammonium borodisalicylate, tetramethylammonium borodisalicylate, tetraethylammonium borodisalicylate, ammonium γ-resorcylate, ammonium paratoluenesulfonate, The main component is a single compound selected from tetramethylammonium paratoluenesulfonate or tetraethylammonium paratoluenesulfonate, or a mixture of the above ammonium salts.

Further, the weight X of the polymer compound represented by the formula (2) and the weight Y of the electron conductive polymer compound which constitute the electrolyte.
Is such that 0.2 ≦ (Y / X) ≦ 1.

Further, the relationship between the number T of molecules of ammonium salt contained in the electrolyte and the total number S of oxygen atoms constituting the polymer compound of (Chemical Formula 2) contained in the electrolyte is 20 ≦ (S
/ T) ≦ 50.

[0016]

[Function] An electrolyte composed of a polymer compound having a polyether skeleton as a basic skeleton and a polyether moiety being a random copolymer of oxyethylene and oxypropylene (Chemical Formula 2), an electron conductive polymer compound and an ammonium salt is used. By using it, the ionic and electronic mixed conductivity of the electrolyte layer is improved, and the impedance of the electrolytic capacitor is lowered. Further, since the electrolyte layer is solid, the electrolytic capacitor using this electrolyte has unprecedented low impedance, high film withstand voltage, and liquid leakage resistance.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrolytic capacitor according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows the structure of an electrolytic capacitor of this embodiment. As shown in the figure, the thickness is 0.1mm,
The diameter of the etching hole is about 1 to 5 microns and the size is 1 cm x
An anode connector 2 is spot-welded to one side of an electrode 1 made of 1 cm aluminum foil. Next, this electrode 1
Solution of boric acid (concentration 80 g /
l), and the aluminum electrode surface was oxidized at a current of 100 mA for 15 minutes to form a dielectric layer 3 made of aluminum oxide, which was used as an anode.

Further, a cathode connector 5 is spot-welded to one side of an electrode 4 made of an aluminum foil having a thickness of 0.1 mm, a diameter of an etching hole of about 1 to 5 microns, and a size of 1 cm × 1 cm. And

Next, in the polymer compound represented by the structural formula (Chemical Formula 2), 4.4 g of the polymer compound represented by (n + m) × l = 50, 4.4 g of polypyrrole powder, and 0.52 g of ammonium borodisalicylate. A stock solution of the polymer electrolyte was prepared by stirring and mixing 0.175 g of diethylene glycol and 4 ml of methyl ethyl ketone.

Subsequently, this polymer electrolyte solution was impregnated into a separator 6 made of polypropylene and having a porosity of 50%, a thickness of 0.1 mm and a size of 1 cm × 1 cm, and then the dielectric surface 3 of the anode and the cathode. The aluminum surface 4 was pressed against each other and stored at 90 ° C. for 3 hours to cure the electrolyte stock solution to form a polymer electrolyte layer 7.

Finally, the whole was sealed with an epoxy resin 8 to prepare an electrolytic capacitor A. Well, the polypyrrole powder is prepared by dispersing 5 g of pyrrole, 5 g of paratoluenesulfonic acid and 5 g of manganese dioxide powder in 50 ml of methyl alcohol, stirring for 3 hours, filtering the remaining powder, and washing with pure water and acetone, This was manufactured by vacuum drying at 100 ° C. for 1 hour. Finally, the polypyrrole powder obtained by the above steps was pulverized to a 200 mesh pass.

(Example 2) In Example 2, an electrolytic capacitor B was prepared using an electron conductive polymer compound different from that in Example 1. The method for producing the electron conductive polymer compound is
Instead of 4.4 g of polypyrrole, which is one of the electrolyte constituent materials used for the electrolytic capacitor A, 4.4 g of polyaniline
The same material and the same construction method as in Example 1 were used except that

The polyaniline powder was prepared by dispersing 5 g of aniline, 5 g of sulfuric acid and 5 g of manganese dioxide in 50 ml of methyl alcohol, stirring the mixture for 3 hours, filtering the remaining powder, and then using pure water and acetone. Washed,
It was obtained by vacuum drying at 100 ° C. for 1 hour. Finally, the polyaniline powder obtained by the above steps was crushed to
The path was set to 00 mesh.

(Third Embodiment) In the third embodiment, the first embodiment,
An electrolytic capacitor C was produced using an electron conductive polymer compound different from that in Example 2.

The manufacturing method was the same except that polythiophene (4.4 g) was used instead of polypyrrole (4.4 g), which is one of the electrolyte constituent materials used for the electrolytic capacitor A.

The polythiophene powder was prepared by dispersing 5 g of thiophene, 5 g of sulfuric acid and 5 g of manganese dioxide powder in 50 ml of methyl alcohol, stirring for 3 hours, filtering the remaining powder, and washing with pure water and acetone. This one
It was produced by vacuum drying at 00 ° C. for 1 hour. Finally, the polythiophene powder obtained by the above steps was crushed and
It was set to 0 mesh pass.

Comparative Example 1 Next, as a comparative example, an electrolytic capacitor D constituted by a polymer electrolyte in which a metal salt was dissolved was prepared.

The manufacturing method is as follows. Instead of 0.52 g of ammonium borodisalicylate, which is one of the electrolyte constituent materials in the preparation of the electrolytic capacitor A, lithium perchlorate of 0.5.
The same material and construction method were used except that 18 g was used.

(Comparative Example 2) Further, as another comparative example, an electrolytic capacitor E using only an electron-conductive polymer compound as an electrolyte constituent material was produced. The same anode as the electrolytic capacitor A was used.

The manufacturing method is as follows:
% Manganese nitrate aqueous solution is applied and impregnated, and then pyrolysis is repeated twice in an electric furnace at 250 ° C., then 5 g of ammonium paratoluenesulfonate and 5 g of pyrrole are dissolved in 50 ml of acetonitrile, and the working electrode is SUS, the counter electrode Titanium as the reference electrode and silver as the reference electrode at an electrode potential of 1.8 V.
After electrolytic polymerization for 0 minutes and washing with pure water and acetone, colloidal carbon and silver paste as a cathode were applied and dried, and a cathode connector was connected with silver paste to obtain an electrolytic capacitor E.

With respect to the electrolytic capacitors A, B and C of Examples 1 to 3 and the electrolytic capacitors D and E of Comparative Examples produced as described above, the frequency characteristics of impedance and the spark generation voltage were evaluated. The results are shown in FIG. 2 and (Table 1), respectively. In FIG. 2, the vertical axis represents the impedance of the electrolytic capacitor and the horizontal axis represents the measurement frequency. As shown in FIG. 2, it can be seen that the electrolytic capacitors A, B, and C of Examples 1 to 3 have lower impedance than the capacitors D and E of Comparative Examples 1 and 2.

[0033]

[Table 1]

The spark generation voltage of each electrolytic capacitor is shown in (Table 1). From (Table 1), the spark generation voltage of the electrolytic capacitors A, B, and C of Examples 1 to 3 has a sufficiently large withstand voltage as compared with the electrolytic capacitor E of Comparative Example 2 including the electrolyte of the electron-conductive polymer compound. You know you have.

(Example 4) In Example 4, in the polymer compound having the structure shown in (Chemical Formula 2), (n + m) × l = 5
0 g of a polymer compound, 0.52 g of ammonium borodisalicylate, 0.175 g of diethylene glycol, and 4 ml of methyl ethyl ketone were mixed by stirring while changing the addition amount of the electron-conductive polymer compound. A stock solution was prepared. The electron conductive polymers used are polypyrrole, polyaniline, and polythiophene. The material composition ratio at this time is such that the weight X of the polymer compound of (Chemical Formula 2) and the weight Y of the electron conductive polymer compound are
The electrolyte was configured so that 0.2 ≦ (Y / X) ≦ 1.

Subsequently, this electrolyte solution was made of polypropylene and had a porosity of 50%, a thickness of 0.1 mm and a size of 1 c.
After being impregnated with a m × 1 cm separator 6, the dielectric surface 3 of the anode and the aluminum surface 4 of the cathode are pressed against each other and stored at a temperature of 90 ° C. for 3 hours to cure the electrolyte stock solution. The electrolyte layer 7 was formed. Finally, the whole is sealed with epoxy resin 8 and electrolytic capacitor F,
G and H were produced.

With respect to the electrolytic capacitors F, G, and H produced as described above, 1 with respect to the composition ratio Y / X of the electrolyte.
The impedance at 20 Hz and the spark generation voltage were evaluated. The measurement results are shown in FIGS. 3 and 4, respectively. The electrolytic capacitor F in the figure is polypyrrole as the electron conductive polymer, and the electrolytic capacitor G is polyaniline.
The electrolytic capacitor H is manufactured by using polythiophene.

In FIG. 3, the vertical axis represents the impedance of the capacitor at 120 Hz, and the horizontal axis represents the composition ratio Y / X of the electrolyte.
Indicates. From FIG. 3, it can be seen that the relationship between the weight X of the polymer compound (Chemical Formula 2) that constitutes the electrolyte and the weight Y of the electron conductive polymer compound is such that the impedance of the capacitor decreases as the Y / X value increases.

In FIG. 4, the vertical axis represents the spark generation voltage at a current density of ² mA / cm ² , and the horizontal axis represents the composition ratio Y / X of the electrolyte. From Figure 4, the spark generation voltage of the capacitor is
It can be seen that as the composition ratio Y / X of the electrolyte increases, it decreases.

From the above results, it can be seen that the electrolytic capacitor using the polymer electrolyte of this example has extremely low impedance and high reliability, even though the solid electrolyte is used.

[0041]

As is apparent from the above description of the embodiments,
In the electrolytic capacitor of the present invention, a solid electrolyte composed of a mixture of an electron-conductive polymer compound and an electrolyte salt is added to a three-dimensional polymer in which the end of the polymer compound of Chemical formula 2 having a polyether polyol as a skeleton structure is cross-linked. A low impedance electrolytic capacitor can be obtained by holding and holding both electrodes to form an electrolytic capacitor. Also,
Since the electrolyte is solid, there is no evaporation or leakage of the electrolyte during storage, and a long-life and highly reliable electrolytic capacitor can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a diagram showing impedance frequency characteristics of the electrolytic capacitors A, B, C, D and E.

FIG. 3 is a diagram showing a relationship between impedance characteristics of the electrolytic capacitors F, G, and H and an electrolyte composition ratio Y / X.

FIG. 4 is a diagram showing the relationship between the spark generation voltage of the electrolytic capacitors F, G and H and the composition ratio Y / X of the electrolyte.

[Explanation of symbols]

 1 Electrode 2 Connector for Anode 3 Dielectric Layer 4 Electrode 5 Connector for Cathode 6 Polymer Electrolyte Layer 7 Sealant

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Takeyama Inventor Kenichi Takeyama 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A polymer compound having a polyether skeleton as a basic skeleton, and the polyether portion of the polyether polyol is a random copolymer of oxyethylene and oxypropylene having a structure of (Chemical Formula 1), and an electronic conductivity. An electrolytic capacitor mainly composed of an electrolyte mainly composed of a polymer compound and an ammonium salt, a dielectric mainly composed of a metal oxide, and an electrically conductive electrode. [Chemical 1] 2. An electrolyte mainly composed of a polymer compound obtained by crosslinking the terminal group of the compound of Chemical formula 1 with a diol compound, an electron conductive polymer compound, and an ammonium salt. Electrolytic capacitor. 3. The electron-conductive polymer compound is pyrrole,
The electrolytic capacitor according to claim 1 or 2, which is mainly composed of a polymer compound having aniline, thiophene or a derivative thereof as a monomer, or a mixture of the polymer compounds. 4. The electrolytic capacitor according to claim 3, wherein the electron conductive polymer compound contains a compound selected from sulfuric acid, paratoluenesulfonic acid or ammonium paratoluenesulfonate, or a mixture of the compounds as a dopant. 5. The ammonium salt is ammonium adipate, ammonium azelate, ammonium benzoate, ammonium borodisalicylate, tetramethylammonium borodisalicylate, tetraethylammonium borodisalicylate, ammonium γ-resorcylate, ammonium paratoluenesulfonate. The electrolytic capacitor according to claim 1, 2, 3, or 4, which is mainly composed of a single compound selected from tetramethylammonium p-toluenesulfonate and tetraethylammonium p-toluenesulfonate, or a mixture of the ammonium salts. 6. The weight X of the polymer compound of (Chemical Formula 1) constituting the electrolyte and the weight Y of the electron conductive polymer compound are
The electrolytic capacitor according to claim 1, 2, 3, 4, or 5, wherein 0.2 ≦ (Y / X) ≦ 1. 7. The relationship between the number T of molecules of ammonium salt contained in the electrolyte and the total number S of oxygen atoms constituting the polymer compound of Chemical formula 1 contained in the electrolyte is 20 ≦ (S /
The electrolytic capacitor according to claim 5, wherein T) ≦ 50.