JP2000297142A - Polymerization liquid for forming solid electrolyte, its preparation, and preparation of solid electrolytic capacitor using same - Google Patents

Polymerization liquid for forming solid electrolyte, its preparation, and preparation of solid electrolytic capacitor using same

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Publication number
JP2000297142A
JP2000297142A JP22240699A JP22240699A JP2000297142A JP 2000297142 A JP2000297142 A JP 2000297142A JP 22240699 A JP22240699 A JP 22240699A JP 22240699 A JP22240699 A JP 22240699A JP 2000297142 A JP2000297142 A JP 2000297142A
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solid electrolyte
polymerization
forming
ph
solution
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JP3346346B2 (en
Inventor
Tomoko Hosokawa
Masato Ozawa
Yukari Shimamoto
正人 小澤
由賀利 島本
知子 細川
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Matsushita Electric Ind Co Ltd
松下電器産業株式会社
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors [EDLCs]; Processes specially adapted for the manufacture thereof or of parts thereof
    • H01G11/22Electrodes
    • H01G11/30Electrodes characterised by their materials
    • H01G11/48Conductive polymers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors [EDLCs]; Processes specially adapted for the manufacture thereof or of parts thereof
    • H01G11/54Electrolytes
    • H01G11/56Solid electrolytes, e.g. gels; Additives therein
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage
    • Y02E60/13Ultracapacitors, supercapacitors, double-layer capacitors

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte for forming a solid electrolyte capable of increasing the capacity and improving the impedance characteristics in a high frequency region, and shortening the electrolytic polymerization time while maintaining the leakage current characteristics. An object of the present invention is to provide a manufacturing method and a method for manufacturing a solid electrolytic capacitor using the same. SOLUTION: A part of the solid electrolyte 3 is formed using a polymerization solution containing at least a polymerizable monomer, an anionic surfactant, a pH adjuster and water and having a pH of 5 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerization solution for forming a solid electrolyte, a method for producing the same, and a method for producing a solid electrolytic capacitor using the same.

[0002]

2. Description of the Related Art With the recent digitization of electronic equipment, capacitors used in such electronic equipment have low impedance in a high-frequency region, and there is an increasing demand for smaller and larger capacitors. Conventionally, as a capacitor used for such a high frequency region, a plastic film capacitor, a mica capacitor, a multilayer ceramic capacitor, and the like have been used. In addition, there are other aluminum dry electrolytic capacitors and aluminum or tantalum solid electrolytic capacitors. In the above aluminum dry electrolytic capacitors, the etched positive / negative aluminum foil is wound through a separator, and a liquid electrolyte is used. .

In the case of an aluminum or tantalum solid electrolytic capacitor, the electrolyte is solidified in order to improve the characteristics of the aluminum dry electrolytic capacitor. To form the solid electrolyte, an anode body is immersed in a manganese nitrate solution, and the solid electrolyte is dried. It is thermally decomposed in a high-temperature furnace at about 350 ° C. to form a manganese oxide layer. In this capacitor, the solid electrolyte has no drawbacks such as electrolyte loss at high temperature, capacity reduction due to dry-up, and functional deterioration caused by solidification at low temperature, and better frequency and temperature characteristics than liquid electrolyte. It shows.

In recent years, in order to increase the electric conductivity of a solid electrolyte, a solid electrolytic capacitor in which a polymerizable monomer such as pyrrole or thiophene is polymerized to form a conductive polymer and this is used as a solid electrolyte has been put to practical use. .

[0005]

SUMMARY OF THE INVENTION A method for forming a solid electrolyte for a capacitor using a conductive polymer as the solid electrolyte is described below.
First, after forming a precoat layer made of a conductive material such as manganese oxide or a conductive polymer on the surface of a dielectric oxide film of a valve metal, power is supplied from an external electrode in a polymerization solution containing a polymerizable monomer. There is an electrolytic polymerization that forms a solid electrolyte of a conductive polymer by performing the method, whereby a solid electrolytic capacitor having good characteristics can be stably manufactured in a relatively short time. In the production of a solid electrolytic capacitor, the productivity can be further improved by increasing the polymerization rate of electrolytic polymerization to reduce the time required for forming a solid electrolyte.

However, as a method of increasing the polymerization rate of the electrolytic polymerization, a method of increasing the polymerization temperature or increasing the polymerization voltage can be considered. However, when the polymerization temperature is increased, volatilization of the polymerizable monomer tends to occur. However, there is a problem that the composition of the polymerization solution becomes unstable, and when the polymerization voltage is increased, in a polymerization solution containing water, another reaction different from polymerization such as electrolysis of water easily occurs. In addition, problems such as a decrease in polymerization efficiency and impedance deterioration due to the adhesion of bubbles generated by electrolysis of water, etc.
It has been difficult to stably exhibit excellent product characteristics as a capacitor and to increase the rate of electrolytic polymerization.

In the case where manganese oxide is used as a part of the solid electrolyte, when the manganese oxide is formed, the conventional thermal decomposition method damages the dielectric oxide film due to the high temperature treatment and causes leakage. There is a phenomenon that the current increases and the manganese oxide formed as a part of the solid electrolyte is difficult to cover the inside of the electrode body, resulting in a low capacity extraction rate and poor impedance characteristics. was there.

The present invention solves such a conventional problem,
An object of the present invention is to provide a polymerization solution for forming a solid electrolyte and a manufacturing method capable of simultaneously improving the performance and reducing the electrolytic polymerization time, and a method for manufacturing a solid electrolytic capacitor using the same.

[0009]

In order to solve the above-mentioned problems, the present invention provides an anionic surfactant having a pH of 5 or less, further having an alkyl group and an aromatic ring, and having a molecular weight of 180 or more, and water. Using a polymerization solution for forming a solid electrolyte containing
The solid electrolyte is formed by performing electrolytic polymerization in the polymerization liquid.

According to the present invention, the rate of polymerization is improved by selectively incorporating an anionic surfactant having excellent undoping resistance as a dopant into the solid electrolyte, and the capacitor is left in the initial stage and at high temperature and high humidity. It is possible to manufacture a solid electrolytic capacitor having excellent inductance characteristics even under such conditions. This is because, when the surfactant is present in the polymerization solution for forming the solid electrolyte containing water, the surfactant assumes a micelle structure in which the polymerizable monomer is incorporated, and thus the anionic material is used as the surfactant. It has the effect of increasing the polymerization rate by making it easier to draw to the anode side where the polymer film is formed, and also because the polymerizable monomer and the anionic surfactant existing in the vicinity are easily taken in as a dopant in the polymer film, the impedance is increased. It is considered that a solid electrolytic capacitor having excellent characteristics can be obtained.

When two or more kinds of anionic surfactants are present in the polymerization solution, it is considered that a material which is easily compatible with the polymerizable monomer is selectively taken in, so that the material which is more easily taken in has an alkyl group and an alkyl group. By using a material having an aromatic ring and a molecular weight of 180 or more, a solid electrolytic capacitor having excellent impedance characteristics can be obtained. In addition, although it is also conceivable that the pH adjuster is an anionic surfactant, a material having an alkyl group and an aromatic ring in a material which is more easily taken in for the same reason as described above and having a molecular weight of 180 or more is used. A solid electrolytic capacitor having excellent impedance characteristics can be obtained.

In addition, by using an acid having an alkyl group or an aromatic ring such as an alkyl phosphate, an alkyl sulfonic acid or an aryl sulfonic acid as a pH adjuster, it can be compared with the case where an acid such as phosphoric acid or sulfuric acid is used. As a result, there is an effect that chemical stress on the dielectric oxide film of the valve action metal is reduced, and excellent leakage current characteristics and impedance characteristics can be obtained.

In the case where manganese oxide is used as a part of the solid electrolyte, when forming the manganese oxide, the dielectric oxide film formed on the valve metal surface should be p-type.
The solid electrolyte according to any one of claims 1 to 4, wherein the solid electrolyte is immersed in a manganese nitrate solution having a pH of 2 or less by adding an H adjustor and thermally decomposed to form a manganese oxide layer. When a conductive polymer is formed by electrolytic polymerization using a forming polymerization solution, the manganese oxide thermally decomposed in this way has a small particle size and is formed homogeneously. It is possible to cover the inside of smaller pores of the film, thereby also preventing deterioration of the dielectric oxide film.

Further, since the manganese oxide having a uniform particle diameter is coated over a wide range, the adhesion of the subsequent low pH polymerization solution to the electrolytically polymerized film can be improved.
In particular, by low pH manganese nitrate solution added and nitrate hydrochloride, sulfuric, phosphoric acid, boric acid, acetic acid and phosphoric acid ester thermal decomposition, in order to form a uniform manganese oxide in minute, during pyrolysis NO X The gas generation path can be secured, the effect of suppressing leakage current can be seen because the stress on the dielectric oxide film is small, and the solid electrolytic capacitor with excellent capacity extraction rate can be obtained because the coverage rate is increased. is there.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention provides a polymer electrolyte for forming a solid electrolyte, which contains at least a polymerizable monomer, an anionic surfactant, a pH adjuster and water and has a pH of 5 or less. That is, by increasing the pH of the polymerization solution to 5 or less, the speed of the polymerization reaction is improved, and by further adding an anionic surfactant to the polymerization solution for forming a solid electrolyte containing water, polymerization and doping can be rapidly performed. This makes it possible to exhibit excellent impedance characteristics as a capacitor, and to reduce the time required for forming a solid electrolyte as compared with the related art.

According to a second aspect of the present invention, in the first aspect, the anionic surfactant is selected from materials having an alkyl group and an aromatic ring and having a molecular weight of 180 or more. The capacitor is selectively taken in as a dopant, and in addition to the effect of the invention according to claim 1, the capacitor is left in a high-temperature and high-humidity state by selectively taking in an anionic surfactant as a dopant. Under such conditions, a solid electrolytic capacitor having excellent undoping resistance and less impedance deterioration can be obtained.

According to a third aspect of the present invention, in the first or second aspect, the polymerizable monomer is pyrrole,
It is selected from at least one of thiophene, aniline, and derivatives thereof, and has an effect of obtaining high conductivity and obtaining a solid electrolytic capacitor having excellent impedance characteristics in a high-frequency region.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the pH adjuster is selected from at least one of an acid material having an alkyl group or an aromatic ring. This has the effect of obtaining a solid electrolytic capacitor having excellent leakage current characteristics and impedance characteristics as compared with the case where phosphoric acid, sulfuric acid, or the like is used.

A fifth aspect of the present invention is a method for producing a polymer electrolyte for forming a solid electrolyte, wherein a polymerizable monomer and an anionic surfactant are mixed in advance, and then an additive and a solvent are added. By pre-mixing the polymerizable monomer and the anionic surfactant, it shows the effect that it becomes more compatible, thereby improving the polymerization rate and making it easier for the anionic surfactant to be doped into the polymer film. This has the effect of obtaining a solid electrolytic capacitor having excellent characteristics.

The invention according to claim 6 is the invention according to claim 5, wherein the anionic surfactant is selected from materials having an alkyl group and an aromatic ring and having a molecular weight of 180 or more. By incorporating an anionic surfactant having an alkyl group and an aromatic ring and having a molecular weight of 180 or more as a dopant in addition to the effect of the invention according to claim 5, the capacitor can be left in high temperature and high humidity. Under such conditions, a solid electrolytic capacitor having excellent undoping resistance and less impedance deterioration can be obtained.

The invention according to claim 7 is the invention according to claim 5 or 6, wherein a pH adjuster is included as one of the additives and the pH is adjusted to 5 or less. By the following, in addition to the effect of the invention described in claim 5 or 6, there is an effect that the polymerization reaction rate can be further improved.

[0022] The invention according to claim 8 provides a method for producing a solid electrolyte by using the polymerization solution for forming a solid electrolyte obtained according to any one of claims 1 to 4 or any one of claims 5 to 7 by electrolytic polymerization. This is a method for manufacturing a solid electrolytic capacitor in which a part of an electrolyte layer is formed, and has an effect that a uniform solid electrolyte can be quickly formed.

According to a ninth aspect of the present invention, the dielectric oxide film formed on the surface of the valve metal is immersed in a manganese nitrate solution having a pH of 2 or less by adding a pH adjuster, After forming the manganese oxide layer by decomposition, a part of the solid electrolyte layer is formed by electrolytic polymerization using the polymerization solution for forming a solid electrolyte according to any one of claims 1 to 4. The manganese oxide pyrolyzed in this way has a small particle size and is formed homogeneously. It can be coated, thereby also preventing deterioration of the dielectric oxide film. Further, since the manganese oxide having a uniform particle size is covered over a wide range, the adhesion can be improved. In particular, since a low-pH manganese nitrate solution is thermally decomposed to form minute and uniform manganese oxides, a NO x gas generation path during thermal decomposition can be secured and stress on the dielectric oxide film is small. Has an effect that a solid electrolytic capacitor having an excellent capacity extraction rate can be obtained because the effect of suppressing a leakage current is seen and the coverage is further increased.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, the pH of the polymerization solution for forming a solid electrolyte is set to 2 or less.
The adhesiveness between the polymer film and the manganese oxide layer obtained by electrolytic polymerization at a pH of 2 or less can be improved, and has an effect of exhibiting excellent capacity extraction ratio and leakage current characteristics.

According to an eleventh aspect of the present invention, in the ninth aspect of the present invention, the pH adjuster added to the manganese nitrate solution is an acid. By thermally decomposing the manganese solution, a fine and uniform manganese oxide is formed, so that the adhesion to the electrolytic polymerized film by the subsequent low pH polymerization solution can be improved, and excellent capacity extraction rate and excellent leakage current characteristics are exhibited. It has the action of:

Hereinafter, specific embodiments of the present invention will be described, but the present invention is not limited thereto.

(Embodiment 1) FIG. 1 is a sectional view showing a structure of a solid electrolytic capacitor according to an embodiment of the present invention. First, a 3 mm × 4 mm aluminum etched with a lead as an anode. Foil 1 was used. A 3% aqueous solution of ammonium adipate was applied thereto at an applied voltage of 12 V and an aqueous solution temperature of 70 ° C. for 60 hours.
By performing anodic oxidation for a minute, a dielectric oxide film 2 was formed on the surface of the aluminum-etched foil 1. Then, after being immersed in a 30% aqueous solution of manganese nitrate and naturally dried,
By performing a thermal decomposition treatment at 300 ° C. for 10 minutes, a manganese oxide layer to be a part of the solid electrolyte layer 3 was formed.

Next, the pyrrole monomer 0.5 mol / L
And sodium propylnaphthalenesulfonate 0.1mo
After mixing 1 / L in advance, water as a solvent and propyl phosphate as a pH adjuster were added to prepare a polymerization solution for forming a solid electrolyte in which the pH was adjusted to 2; The electrode was brought close to the element surface, and electrolytic polymerization was performed at a liquid temperature of 30 ° C. and a polymerization voltage of 3 V to form a solid electrolyte layer 3. Thereafter, a carbon layer 4 obtained by applying and drying a colloidal carbon suspension as a cathode extraction layer and a silver layer 5 obtained by applying and drying a silver paste are formed, and the carbon layer 4 and the silver layer 5 are formed. In addition, a cathode lead portion was provided. Then, the package was completed with epoxy resin to complete ten solid electrolytic capacitors. The rating of this solid electrolytic capacitor is 6.3V 10
μF.

(Example 2) Example 1 was repeated except that the pH of the polymerization solution for forming a solid electrolyte was adjusted to 0.5 by changing the amount of propyl phosphate ester as a pH adjuster.
Similarly, 10 solid electrolytic capacitors were produced.

Example 3 A solid electrolytic capacitor 10 was prepared in the same manner as in Example 1 except that the pH of the polymer solution for forming a solid electrolyte was adjusted to 5 by changing the amount of propyl phosphate ester as a pH adjuster. Individual pieces were produced.

Example 4 Ten solid electrolytic capacitors were produced in the same manner as in Example 1 except that sodium propylnaphthalenesulfonate was changed to sodium dodecylbenzenesulfonate.

Example 5 Ten solid electrolytic capacitors were prepared by adjusting the pH of the polymerization solution to 2 in the same manner as in Example 1 except that the propyl phosphate in Example 1 was changed to butyl ether phosphate. .

Example 6 The procedure of Example 1 was repeated except that the pH adjuster propyl phosphate was changed to propyl sulfonic acid, and the pH of the polymerization solution was adjusted to 2 by changing the amount of propyl sulfonic acid added. Ten solid electrolytic capacitors were produced in the same manner as in Example 1.

(Example 7) Naphthalenesulfonic acid was used as the propyl phosphate ester as the pH adjuster of Example 1,
Further, 10 solid electrolytic capacitors were produced in the same manner as in Example 1, except that the pH of the polymerization solution was adjusted to 2 by changing the amount of naphthalesulfonic acid added.

Example 8 Ten solid electrolytic capacitors were produced in the same manner as in Example 1 except that the polymerization voltage during electrolytic polymerization in Example 1 was changed from 3 V to 2 V.

(Example 9) A dielectric oxide film 2 is formed on the outer surface of an aluminum-etched foil 1 serving as an anode in the same manner as in Example 1, then immersed in a 30% aqueous solution of manganese nitrate and air-dried. After that, a manganese oxide layer which became a part of the solid electrolyte layer 3 was formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. Thereafter, 0.5 mol / L of a pyrrole monomer and 0.1 mol / L of sodium propylnaphthalesulfonate are individually mixed with water as a solvent, and then mixed.
Addition of propyl phosphate as an H regulator
A polymerization liquid for forming a solid electrolyte in which H was adjusted to 2 was prepared, a polymerization initiation electrode was brought close to the element surface in the polymerization liquid, and electrolytic polymerization was carried out at a liquid temperature of 30 ° C. and a polymerization voltage of 3 V to obtain a solid electrolyte layer 3. Was formed. After that, a cathode lead portion composed of the carbon layer 4 and the silver layer 5 was formed in the same manner as in Example 1, and the exterior was applied to complete ten solid electrolytic capacitors.

Comparative Example 1 A dielectric oxide film 2 was formed on the outer surface of an aluminum-etched foil 1 serving as an anode in the same manner as in Example 1, then immersed in a 30% aqueous solution of manganese nitrate and air-dried. After that, a manganese oxide layer to be a part of the solid electrolyte layer 3 was formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. After this, the pyrrole monomer 0.1.
After 5 mol / L and 0.1 mol / L sodium propylnaphthalenesulfonate are mixed in advance, water as a solvent is added, and a polymerization initiating electrode is brought close to the element surface in a polymerization solution prepared at a liquid temperature of 30 ° C. Electrolytic polymerization was performed at a voltage of 3 V to form a solid electrolyte layer 3. In this case, the pH of the polymerization solution was 6.2. After that, a cathode lead portion composed of the carbon layer 4 and the silver layer 5 was formed in the same manner as in Example 1, and the exterior was applied to complete ten solid electrolytic capacitors.

Comparative Example 2 A dielectric oxide film 2 was formed on the outer surface of an aluminum-etched foil 1 serving as an anode in the same manner as in Example 1, and then immersed in a 30% aqueous solution of manganese nitrate to dry naturally. After that, a manganese oxide layer to be a part of the solid electrolyte layer 3 was formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. After this, the pyrrole monomer 0.1.
5mol / L and potassium propylsulfonate 0.1mo
In a polymerization solution prepared by adding water as a solvent after mixing 1 / L in advance, a polymerization initiating electrode is brought close to the element surface, and electrolytic polymerization is performed at a liquid temperature of 30 ° C. and a polymerization voltage of 3 V to perform solid polymerization. 3 was formed. In this case, the pH of the polymerization solution was 5.8. After that, a cathode lead portion composed of the carbon layer 4 and the silver layer 5 was formed in the same manner as in Example 1, and the exterior was applied to complete ten solid electrolytic capacitors.

Comparative Example 3 A dielectric oxide film 2 was formed on the outer surface of an aluminum-etched foil 1 serving as an anode in the same manner as in Example 1, and then immersed in a 30% aqueous solution of manganese nitrate to air dry. After that, a manganese oxide layer to be a part of the solid electrolyte layer 3 was formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. After this, the pyrrole monomer 0.1.
5 mol / L and sodium propylnaphthalenesulfonate 0.1 mol / L are mixed in advance, and then propylene carbonate as a solvent and propyl phosphate as a pH adjuster are added to adjust the pH to 2 to form a solid electrolyte-forming polymerization. A solution was prepared, and a polymerization initiation electrode was brought close to the element surface in the polymerization solution.
The solid electrolyte layer 3 was formed by performing electrolytic polymerization with V. After that, a cathode lead portion composed of the carbon layer 4 and the silver layer 5 was formed in the same manner as in Example 1, and the exterior was applied to complete ten solid electrolytic capacitors.

Comparative Example 4 A dielectric oxide film 2 was formed on the outer surface of an aluminum-etched foil 1 serving as an anode in the same manner as in Example 1, and then immersed in a 30% aqueous solution of manganese nitrate to dry naturally. After that, a manganese oxide layer to be a part of the solid electrolyte layer 3 was formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. Next, the pyrrole monomer 0.5
mol / L and 0.1 mol / L of sodium propylnaphthalenesulfonate were mixed in advance, and then water as a solvent and phosphoric acid as a pH adjuster were added to prepare a polymerization solution for forming a solid electrolyte in which the pH was adjusted to 2. In this polymerization solution, the polymerization initiation electrode is brought close to the element surface, and the
Electropolymerization was performed at a polymerization temperature of 3 ° C. to form a solid electrolyte layer 3. After that, a cathode lead portion composed of the carbon layer 4 and the silver layer 5 was formed in the same manner as in Example 1, and the exterior was applied to complete ten solid electrolytic capacitors.

The solid electrolytic capacitors produced in Examples 1 to 9 of the first embodiment and Comparative Examples 1 to 4 were aged, and then the initial characteristics of the solid electrolytic capacitors were measured. The solid electrolytic capacitor was heated to 85 ° C 85
% After 1000 hours. The average value of these results and Example 1 in Embodiment 1
Table 9 shows the time required until the entire device was covered with the conductive polymer when electrolytic polymerization was performed under the conditions of Comparative Examples 1 to 4 and Comparative Examples 1 to 4.

Further, in Embodiment 1, Examples 1 to
3, 5 and the amount of dopant incorporated in the electrolytically polymerized film of the solid electrolytic capacitor produced according to Comparative Examples 1 to 3,
It was estimated from the analysis results of the amounts of S and P in the polymer film. Comparative Example 1
The molar ratio when the amount of sodium propylnaphthalenesulfonate incorporated into the polymerized film of Example 1 is 1 is shown below. In Example 1, sodium propylnaphthalenesulfonate 1.21, propylphosphate 0.02, in Example 2, sodium propylnaphthalenesulfonate 1.17, propylphosphate 0.03, and in Example 3, propylnaphthalenesulfone Sodium acid 1.1
9, 0.02 propyl phosphate, 1.16 sodium propylnaphthalenesulfonate in Example 5, 0.07 butoxyethyl phosphate, or 0.64 potassium propylsulfonate in Comparative Example 2; It was sodium naphthalene sulfonate 0.38 and propyl phosphate 0.32.

[0043]

[Table 1]

From Table 1, it is found that Examples 1 to 9 and Comparative Examples 1 and 2
From the comparison of 2, it can be seen that setting the pH to 5 or less can greatly reduce the time required for electrolytic polymerization. Further, by comparing Examples 1 to 9 and Comparative Examples 1 and 2,
It is understood that the polymerization time can be shortened by adding an anionic surfactant as an electrolyte, and further excellent impedance characteristics are exhibited. This excellent impedance characteristic is considered to be due to the fact that the use of an anionic surfactant increased the amount of dopant incorporated into the polymer film. Further, according to the comparison between Example 1 and Comparative Example 3, the polymerization time can be shortened by performing the electrolytic polymerization in the polymerization solution containing water, and the impedance characteristics at the initial stage and after standing at 85 ° C. and 85% for 1000 hours are excellent. I understand. This excellent impedance characteristic is obtained by including water in the polymerization solution, and sodium propylnaphthalenesulfonate, an anionic surfactant with excellent de-doping resistance, was selectively incorporated into the polymer film. it is conceivable that.

Further, according to the comparison between Examples 1 to 9 and Comparative Example 4, the use of an acid material having an alkyl group or an aromatic ring as a pH adjuster allows the initial and 85 ° C. 85%
It can be seen that the leakage current characteristics after leaving for 1000 hours are excellent. In addition, a comparison between Example 8 and Comparative Example 1 shows that even when the polymerization voltage is lowered, the time required for polymerization can be reduced as compared with the conventional case. The polymerization efficiency can be increased by reducing side reactions such as electrolysis of water, and excellent impedance characteristics can be obtained.

In addition, according to the comparison between Example 1 and Example 9, when producing a polymer solution for forming a solid electrolyte, a solvent and an additive are added after a polymerizable monomer and an anionic surfactant are mixed in advance. This indicates that the polymerization time can be shortened, and further excellent impedance characteristics are exhibited.

(Embodiment 2) FIG. 2 is a sectional view showing a structure of a solid electrolytic capacitor according to an embodiment of the present invention. First, a 3 mm × 4 mm aluminum etched with a lead as an anode. Foil 6 was used. A 3% aqueous solution of ammonium adipate was applied thereto at an applied voltage of 12 V and an aqueous solution temperature of 70 ° C. for 60 hours.
By performing anodic oxidation for minutes, a dielectric oxide film 7 was formed on the surface of the aluminum-etched foil 6. Then p
After being immersed in a 30% aqueous solution of manganese nitrate having H of 3.73 and air-dried, a manganese oxide layer to be a part of the solid electrolyte layer 8 is formed by performing a thermal decomposition treatment at 300 ° C. for 10 minutes. did.

Next, the pyrrole monomer 0.5 mol / L
And sodium propylnaphthalenesulfonate 0.1mo
After mixing 1 / L in advance, water as a solvent and propyl phosphate as a pH adjuster were added to prepare a polymerization solution for forming a solid electrolyte in which the pH was adjusted to 2; The electrode was brought close to the element surface, and electrolytic polymerization was performed at a liquid temperature of 30 ° C. and a polymerization voltage of 3 V to form a solid electrolyte layer 8. Thereafter, a carbon layer 9 obtained by applying and drying a colloidal carbon suspension as a cathode extraction layer and a silver layer 10 obtained by applying and drying a silver paste are formed, and the carbon layer 9 and the silver layer 10 are combined. To form a cathode drawer. Then, the package was completed with epoxy resin to complete ten solid electrolytic capacitors. The rated voltage of this solid electrolytic capacitor is 6.3V
It is.

(Example 2) FIG. 2 is a sectional view showing a structure of a solid electrolytic capacitor according to an embodiment of the present invention, in which a 3 mm × 4 mm aluminum-etched foil 6 with a lead as an anode was used. A 3% aqueous solution of ammonium adipate was applied thereto, and an applied voltage of 12 V and an aqueous solution temperature of 70% were used.
By performing anodization at 60 ° C. for 60 minutes, a dielectric oxide film 7 was formed on the surface of the aluminum-etched foil 6. Thereafter, nitric acid as a pH adjuster was added to a 30% aqueous solution of manganese nitrate having a pH of 3.73, and the resultant was immersed in a solution having a pH of 2 and naturally dried, and then thermally decomposed at 300 ° C. for 10 minutes. As a result, a manganese oxide layer to be a part of the solid electrolyte layer 8 was formed.

Next, the pyrrole monomer 0.5 mol / L
And sodium propylnaphthalenesulfonate 0.1mo
After mixing 1 / L in advance, water as a solvent and propyl phosphate as a pH adjuster were added to prepare a polymerization solution for forming a solid electrolyte in which the pH was adjusted to 2; The electrode was brought close to the element surface, and electrolytic polymerization was performed at a liquid temperature of 30 ° C. and a polymerization voltage of 3 V to form a solid electrolyte layer 8. Thereafter, a carbon layer 9 obtained by applying and drying a colloidal carbon suspension as a cathode extraction layer, and a silver layer 10 obtained by applying and drying a silver paste are formed, and the carbon layer 9 and the silver layer 10 are formed. In addition, a cathode lead portion was provided. Then, the package was completed with epoxy resin to complete ten solid electrolytic capacitors. The rated voltage of this solid electrolytic capacitor is 6.3.
V.

(Example 3) In Example 2, the pH of the manganese nitrate solution was adjusted to 1.0 by changing the amount of nitric acid added.
Ten solid electrolytic capacitors were produced in the same manner as in Example 2 except that the value was adjusted to 5.

Example 4 Ten solid electrolytic capacitors were manufactured in the same manner as in Example 2, except that the pH of the manganese nitrate solution was adjusted to 1 by changing the amount of nitric acid added.

(Example 5) In Example 2, the pH of the manganese nitrate solution was adjusted to 0.1 by changing the amount of nitric acid added.
Ten solid electrolytic capacitors were produced in the same manner as in Example 2 except that the value was adjusted to 5.

(Example 6) In Example 2, the pH of the manganese nitrate solution was adjusted to 0.1 by changing the amount of nitric acid added.
10 solid electrolytic capacitors were produced in the same manner as in Example 2 except that the value was adjusted to 3.

(Example 7) In Example 2, the pH of the manganese nitrate solution was adjusted to 0.1 by changing the amount of nitric acid added.
10 solid electrolytic capacitors were produced in the same manner as in Example 2 except that the value was adjusted to 1.

Example 8 Ten solid electrolytic capacitors were manufactured in the same manner as in Example 2 except that the pH of the manganese nitrate solution was adjusted to 0 or less by changing the amount of nitric acid added.

Example 9 Ten solid electrolytic capacitors were manufactured in the same manner as in Example 2, except that the pH of the manganese nitrate solution was adjusted to 0 or less by adding sulfuric acid.

Example 10 Ten solid electrolytic capacitors were produced in the same manner as in Example 2, except that the pH of the manganese nitrate solution was adjusted to 0 or less by adding hydrochloric acid.

Comparative Example 1 As in Example 1, a 3 mm × 4 mm aluminum-etched foil 6 with a lead was used as an anode, and a 3% aqueous solution of ammonium adipate was applied thereto, and an applied voltage of 12 V was used. 60 at 70 ° C
By performing anodic oxidation for minutes, a dielectric oxide film 7 was formed on the surface of the aluminum-etched foil 6. Then p
A manganese oxide layer which becomes a part of the solid electrolyte layer 8 is formed by immersing in a 30% aqueous solution of manganese nitrate having H of 3.73, air-drying, and then performing a thermal decomposition treatment at 300 ° C. for 10 minutes. did.

Next, the pyrrole monomer 0.5 mol / L
And sodium propylnaphthalenesulfonate 0.1mo
After mixing 1 / L in advance, water as a solvent was mixed to prepare a polymerization solution for forming a solid electrolyte. In this polymerization solution, a polymerization initiating electrode was brought close to the element surface, a liquid temperature of 30 ° C., and a polymerization voltage of 3 V. Was carried out to form a solid electrolyte layer 8. Thereafter, a carbon layer 9 obtained by applying and drying a colloidal carbon suspension as a cathode extraction layer and a silver layer 10 obtained by applying and drying a silver paste are formed, and the carbon layer 9 and the silver layer 10 are combined. To form a cathode drawer. Then, the package was completed with epoxy resin to complete ten solid electrolytic capacitors. The rated voltage of this solid electrolytic capacitor is 6.3V.

Comparative Example 2 In the same manner as in Example 1, a 3 mm × 4 mm aluminum-etched foil 6 with a lead was used as an anode, and a 3% aqueous solution of ammonium adipate was applied thereto, and an applied voltage of 12 V and an aqueous solution were used. 60 at 70 ° C
The dielectric oxide film 7 was formed on the surface of the aluminum-etched foil 6 by performing anodic oxidation for minutes. Then pH
By adding nitric acid as a pH adjuster to a 30% aqueous solution of manganese nitrate having a pH of 3.73, immersing the resultant in a solution having a pH of 2 and allowing it to dry naturally, and performing a thermal decomposition treatment at 300 ° C. for 10 minutes. Then, a manganese oxide layer to be a part of the solid electrolyte layer 8 was formed.

Next, the pyrrole monomer 0.5 mol / L
And sodium propylnaphthalenesulfonate 0.1mo
After mixing 1 / L in advance, water as a solvent was mixed to prepare a polymerization solution for forming a solid electrolyte. In this polymerization solution, a polymerization initiating electrode was brought close to the element surface, a liquid temperature of 30 ° C., and a polymerization voltage of 3 V. Was carried out to form a solid electrolyte layer 8. Thereafter, a carbon layer 9 obtained by applying and drying a colloidal carbon suspension as a cathode extraction layer and a silver layer 10 obtained by applying and drying a silver paste are formed, and the carbon layer 9 and the silver layer 10 are combined. To form a cathode drawer. Then, the package was completed with epoxy resin to complete ten solid electrolytic capacitors. The rated voltage of this solid electrolytic capacitor is 6.3V.

Further, the solid electrolytic capacitors produced in Examples 1 to 10 and Comparative Examples 1 and 2 were aged, and thereafter, initial characteristics of the solid electrolytic capacitors were measured. The average of these results is shown in (Table 2).

[0064]

[Table 2]

By comparing the above Comparative Example 1 and Example 1 with Comparative Example 2 and Example 2, by adding a pH adjuster to lower the pH of the manganese nitrate solution to 2 or less, the capacity extraction ratio and the leakage current characteristics were obtained. In addition, those having excellent impedance / ESR characteristics in a high frequency region can be obtained. In addition, a comparison between Examples 1 to 10 and Comparative Examples 1 and 2 reveals that by setting the pH at the time of electrolytic polymerization to 2, excellent capacity extraction rate, leakage current characteristics, and impedance characteristics can be obtained.

The excellent characteristics are obtained by immersing in a manganese nitrate solution having a pH of 2 or less by adding a pH adjuster and thermally decomposing the manganese oxide layer to form a manganese oxide layer. When the conductive polymer layer is formed by electrolytic polymerization using the polymerization solution for forming a solid electrolyte according to any one of the above, the particle size of the manganese oxide thus thermally decomposed is small and uniform. Therefore, it is possible to cover the inside of smaller pores of the dielectric oxide film, thereby preventing deterioration of the dielectric oxide film.

Further, since the manganese oxide having a uniform particle diameter is coated over a wide range, the adhesion of the subsequent low pH polymerization solution to the electrolytically polymerized film can be improved.
In particular, by thermally decomposing a low-pH manganese nitrate solution to which an acid such as nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, or a phosphoric acid ester is added, a minute and uniform manganese dioxide is formed. x A gas generation path can be secured,
The effect of suppressing the leakage current is seen because the stress on the dielectric oxide film is small, and the solid electrolytic capacitor having an excellent capacity extraction rate can be obtained because the covering rate is increased.

In the first and second embodiments, only the solid electrolytic capacitor using the valve metal aluminum as the anode has been described. However, the present invention is not limited to this. It goes without saying that the same effect can be obtained with other substances such as tantalum, niobium, and titanium, which are valve action metals having an oxide film.

Further, in the first and second embodiments, only the case where pyrrole is used as the polymerizable monomer constituting the conductive polymer has been described. However, the present invention is not limited to this, and the present invention is not limited thereto. It goes without saying that similar effects can be obtained with other substances such as thiophene, aniline or derivatives thereof as monomers constituting the molecule.

In the first embodiment, only the case where a manganese oxide is used as the precoat layer which is a part of the solid electrolyte layer has been described. However, the present invention is not limited to this, and it is not limited thereto. Needless to say, the same effect can be obtained when other conductive material is used as the precoat.

[0071]

As described above, according to the present invention, the electrolytic polymerization is carried out using a polymer electrolyte for forming a solid electrolyte containing at least a polymerizable monomer, an anionic surfactant, a pH adjuster and water and having a pH of 5 or less. This makes it possible to maintain characteristics such as excellent impedance and leakage current as a capacitor and to shorten the time of electrolytic polymerization. Further, by using such a polymer electrolyte for forming a solid electrolyte and adding a pH adjuster,
After immersion in a manganese nitrate solution with H of 2 or less and thermal decomposition to form a manganese oxide layer, electrolytic polymerization is performed to form a conductive polymer layer, so that the capacity extraction rate and leakage A solid electrolytic capacitor having excellent current characteristics and high impedance / ESR characteristics in a high frequency region can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a solid electrolytic capacitor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a solid electrolytic capacitor according to a second embodiment of the present invention.

[Explanation of symbols]

 1,6 Aluminum etched foil 2,7 Dielectric oxide film 3,8 Solid electrolyte layer 4,9 Carbon layer 5,10 Silver layer

Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat II (Reference) H01G 9/028 H01G 9/02 331G 331H (72) Inventor Masato Ozawa 1006 Odakadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. F term (reference) 4J002 CE001 EV256 EW046 FD316 GQ00 GQ02 4J032 BA03 BA13 BB01 BC22 BC25 BC32 CG01 4J043 QB02 RA08 SA05 SB01 XA12 XA21 ZB47

Claims (11)

[Claims]
1. A solid electrolyte-forming polymerization solution containing at least a polymerizable monomer, an anionic surfactant, a pH adjuster and water, and having a pH of 5 or less.
2. The method according to claim 1, wherein the anionic surfactant has an alkyl group and an aromatic ring, is selected from materials having a molecular weight of 180 or more, and is selectively incorporated into the solid electrolyte as a dopant. The polymer solution for forming a solid electrolyte according to claim 1.
3. The polymerization solution for forming a solid electrolyte according to claim 1, wherein the polymerizable monomer is selected from at least one of pyrrole, thiophene, aniline and derivatives thereof.
4. The polymerization solution for forming a solid electrolyte according to claim 1, wherein the pH adjuster is selected from at least one of an acid material having an alkyl group or an aromatic ring.
5. A method for producing a polymerization solution for forming a solid electrolyte, wherein a polymerizable monomer and an anionic surfactant are preliminarily mixed, and then an additive and a solvent are added.
6. The method according to claim 5, wherein the anionic surfactant has an alkyl group and an aromatic ring and is selected from materials having a molecular weight of 180 or more. .
7. A pH adjuster as one of the additives,
The method for producing a polymerization solution for forming a solid electrolyte according to claim 5, wherein the pH is adjusted to 5 or less.
8. A part of the solid electrolyte layer is subjected to electrolytic polymerization using the polymerization solution for forming a solid electrolyte obtained according to any one of claims 1 to 4, or any one of claims 5 to 7. A method for manufacturing a solid electrolytic capacitor to be formed.
9. A manganese oxide film formed by immersing a dielectric oxide film formed on the surface of a valve metal in a manganese nitrate solution having a pH of 2 or less by adding a pH adjuster, and thermally decomposing the manganese oxide film. Claim 1 after forming the layer.
A method for producing a solid electrolytic capacitor, wherein a part of a solid electrolyte layer is formed by electrolytic polymerization using the polymerization solution for forming a solid electrolyte according to any one of the above-mentioned items.
10. The method for producing a solid electrolytic capacitor according to claim 9, wherein the pH of the polymerization solution for forming a solid electrolyte is 2 or less.
11. The method according to claim 9, wherein the pH adjuster added to the manganese nitrate solution is an acid.
JP22240699A 1999-02-10 1999-08-05 Polymerization liquid for forming solid electrolyte and method for producing the same Expired - Fee Related JP3346346B2 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6671168B2 (en) 2001-11-30 2003-12-30 Matsushita Electric Industrial Co., Ltd. Solid electrolytic capacitor and method for manufacturing the same
US7070631B2 (en) 2001-02-08 2006-07-04 Showa Denko K.K. Method for producing aluminum foil for capacitor and solid electrolytic capacitor
JP2007197739A (en) * 2006-01-24 2007-08-09 Eamex Co Method for producing actuator element made from electroconductive polymer

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7070631B2 (en) 2001-02-08 2006-07-04 Showa Denko K.K. Method for producing aluminum foil for capacitor and solid electrolytic capacitor
US6671168B2 (en) 2001-11-30 2003-12-30 Matsushita Electric Industrial Co., Ltd. Solid electrolytic capacitor and method for manufacturing the same
JP2007197739A (en) * 2006-01-24 2007-08-09 Eamex Co Method for producing actuator element made from electroconductive polymer
JP4644130B2 (en) * 2006-01-24 2011-03-02 イーメックス株式会社 Method for manufacturing conductive polymer actuator element

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