JPS61239617A - Solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses an oxidized polymer containing aniline derivative dopane, which has high electrical conductivity and excellent adhesion to a dielectric film, as a solid electrolyte. This invention relates to solid electrolytic capacitors with good performance.

[Problems to be solved by the prior art and the invention] Conventional solid electrolytic capacitors, such as aluminum electrolytic capacitors, consist of: ■ an aluminum oxide layer as a dielectric on a porous aluminum foil with a large specific surface area that has been subjected to a tweezing process; (J) It consists of a structure in which the electrolytic paper between the cathode foil and the cathode foil is impregnated with a liquid electrolyte, but the fact that this electrolyte is liquid causes problems such as leakage and is not desirable. ,
Therefore, attempts have been made to replace this N-conducting layer with a solid electrolyte. These solid electrolytic capacitors have a structure in which a solid electrolyte is attached to a film-forming metal such as aluminum or tantalum that has an anodized film. Manganese dioxide, which is formed by However, the high heat required during this thermal decomposition and the N generated
Due to the oxidation effect of Ox gas, etc., the metal oxide film of dielectric materials such as aluminum and tantalum is damaged, resulting in a decrease in withstand voltage T and U, an increase in leakage current, and extremely serious drawbacks such as deterioration of dielectric properties. There is. There is also a second step called reconstitution.

In order to compensate for these drawbacks, attempts have been made to form a solid electrolyte layer without applying high heat, that is, to use a highly conductive organic semiconductor material as a solid electrolyte. For example, 7,7.8.8-tetracyanoquinodimethane (TCN
Q) A solid electrolytic capacitor containing a conductive polymer composition containing a complex salt as a solid electrolyte, Nn-propyliso:1 norine and 7.7.8 described in JP-A-58-17609. A solid electrolytic capacitor containing a complex salt of 8-tetracyanoquinodimethane as a solid electrolyte is known. These -rcNQ complex salt compounds have poor adhesion to the anodic oxide film and have electrical conductivity of 10-3 to IO's.
/1 car, which is insufficient, the capacitance IR value of the conductor is small and the dielectric loss is large. It also has poor thermal stability and reliability.

[Means for Solving the Problems] An object of the present invention is to solve the above-mentioned conventional drawbacks,
An object of the present invention is to provide a solid electrolytic capacitor using a polymeric conductor having high conductivity and good adhesion to a dielectric film as a solid electrolyte.

As a result of careful parsimony, the inventors have found that this object is achieved by using a dopant-containing oxidized polymer of an aniline derivative as the solid electrolyte.

That is, according to the present invention, R1-R4 may be different or the same and represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group. However, all of R1-R1 are not hydrogen atoms at the same time. The present invention relates to a solid electrolytic capacitor characterized in that a dopant-containing oxidized polymer of an aniline derivative represented by the following formula is used as a solid electrolyte.

The solid electrolyte used in the present invention has the general formula (
It is obtained by combining 44 anilines represented by 1) with the general formula (2) [However, R1-R4 are the same as the above general formula (+>).

] It is a dopant-containing oxidized polymer of an aniline derivative containing at least 50 mol% of repeating units represented by the following. 50 mol% of repeating units represented by general formula (2)
If it is less than that, the electrical conductivity will not be sufficient.

Specific examples of the aniline derivative having no substituent at the p-position represented by the general formula (1) include 2-methoxy 2,-aniline, 3-methoxy-aniline, 2,3-thume1-xyaniline, 2, 5-dimethoxy-aniline, 3.5
- Tsume 1~xyaniline, 2.6-symethoxyatriline, 2-ethoxyaniline, 2-ethoxy-3-methoxy-aniline, 3-ethyl-xy-aniline, 2.3
-Die1hexyaniline, 2,5-jethoxy-aniline, 2,6-dinithoxyaniline, 3,5-jethoxy-aniline, 2,6-dinitoxyaniline, 2-
Methoxy-3-ethoxy-aniline, 2-methoxy-5
-Ethoxy-aniline, 2,3.6-drimethoxyaniline, 2,3.54rimethoxyaniline, 2.3.
5.6-thitramethoxyaniline, 2,3.5.6-
Citraethoxyaniline, 2,3-dimethyl-aniline, 2-methyl"3-methoxy-aniline, 2,3.5
．． Examples include, but are not limited to, 6-butramethyl-aniline, 2-methyl-5-methoxy-aniline, 3,5-dimethyl-aniline, and the like. Among the above-mentioned aniline derivatives, those having two or more substituents are preferable, and in particular, dopant-containing oxidized polymers of alkoxyaniline having two or more alkoxy group substitutions have good solubility in organic solvents and are electrically conductive. It can be preferably used because it has high properties.

The oxidized polymer containing the aniline derivative Dopan 1 may be produced by any method.

As the oxidized polymer of the aniline derivative contained in Dorpan 1, an oxidized polymer of the aniline derivative which is not doped with Dorpan 1 is produced in advance, and this is doped with a dopant in the presence of the oxidized polymer contained in Dorpan 1 and the dopant. Examples include dopant-containing oxidized polymers obtained by oxidative polymerization of aniline derivatives.

- Among the dopant-containing oxidized polymers of the aniline derivatives listed in V, if the oxidized polymers already contain a dopant,
This is preferable since it is not necessary to dope Dorpan I in general, but depending on the dopant stone contained in the oxidized polymer of the aniline derivative, Dorpan 1 may be further doped.

The oxidized polymer of aniline derivative doped with dopane 1- can be prepared by electrochemically or chemically oxidatively polymerizing the aniline derivative.

In the case of electrochemical polymerization, the polymerization of aniline derivatives is carried out by anodic oxidation, about 0.01-50 m A/cd,
The electrolytic voltage is usually in the range of 1 to 300 V, and a constant current method, a constant voltage method, and any other method can be used. The polymerization is carried out in an aqueous solution, an alcoholic solvent, or a mixed solvent thereof, preferably in an aqueous solution. The alcohol may or may not dissolve the resulting oxidized polymer. The alcohol used depends on the type of aniline derivative, but methyl alcohol, ethyl alcohol, ethylene glycol, propyl alcohol, butyl alcohol, etc. are usually used.

There is no particular restriction on pl+ of a suitable electrolytic solution, but preferably 11+1 is 3 or less, particularly preferably pH is 2 or less. A specific example of the acid used for +111 adjustment is HCu.

Examples include, but are not limited to, 1''BF4, CF3CO0I-1, f-12SO4, and 1-INO3.

The dopant used when polymerizing the above aniline derivative by an electrochemical method is C[,1-.

Br −, F−, 13Fi , CD, O′;+ , , I
Oi.

AS Fi , Sb Fii , PFa , Si F'
i.

AS Fa, FSOi, H80j, 802:.

Salts containing groups such as CFa SO''i , CFa COO- and NOi are used, and the resulting oxidized polymers contain these anions as dopants.

These salts contain cations such as alkali metals such as lithium, sodium and potassium and quaternary ammonium ions.

In the thus obtained oxidized polymer containing Dolpan,
Usually 10 to 90 mol % (per unit) of anion is contained as a dopant.

According to the electrochemical method, the oxidized polymer containing Dopan 1 is usually deposited on the anode as a black polymer, which can be used after being washed off and dried.

In the case of chemical polymerization, for example, aniline derivatives can be reacted with oxidizing strong acids in aqueous solution or with strong acids and
*1 Oxidative polymerization can be carried out in combination with oxides such as potassium persulfate. Since the oxidized polymer obtained by this method can be obtained in powder form, it can be separated and dried before use.

In this case too, the oxidized polymer has a corresponding anion
, 1.1 doped state. The resulting dopant-containing oxidized polymer usually contains 10 to 90 mol%.
Anion (per unit of monomer) is included as dolpan 1-.

In the present invention, when an oxidized polymer of an aniline derivative which is not doped with a dopant in advance is produced and the oxidized polymer is doped with a dopant to obtain a dopant-containing oxidized polymer, and when the oxidized polymer containing a dopant is further doped with a dopant. The dopant used is the same as the dopant used in the oxidative polymerization of the aniline derivative doped with the dopant.

The doping of the dopant depends on whether the oxidized polymer of the aniline derivative to be used already contains the dopant or not, so it cannot be determined unconditionally, but usually the proportion of the dopant in the oxidized polymer of the aniline derivative is It is doped to a concentration of 10 to 90 mol % (per monomer unit).

Aniline derivative Dovan] containing oxidized polymer [yo, -
- Can be easily dissolved in commonly used organic solvents to form a small combined solution. A solid electrolyte can be easily obtained by applying this polymer solution onto a dielectric film and then removing the organic solvent from the polymer solution. Furthermore, the solid electrolyte obtained by this method has good stability in air, and hardly any decrease in electrical conductivity is observed even if it is left in air for a long time.

The organic solvent used to dissolve the oxidized polymer containing the aniline derivative Bepan 1 varies depending on the type of the dopant-containing oxidized polymer of the aniline derivative used, so it cannot be specified specifically, but the aniline derivative J: aliphatic and aromatic ketones, ethers, esters, amides, nitriles, carbonates, carboxylic acids, halogen compounds, sulfolane, as long as the dopant-containing oxidized polymer dissolves in compounds, nitro compounds, sulfoxides, lactams, lactones, saturated and unsaturated heterocyclic compounds, and the like.

Methods for producing the polymer solution iii include (i) a method of dissolving an anion-doped oxidized polymer obtained by electrochemical oxidative polymerization in the above-mentioned organic solvent; (iii) chemically or electrochemically doping an oxidized polymer which is not doped with a chemically synthesized anion with a dopant; Examples include a method of dissolving in an organic solvent, and (iv) a method of dissolving a chemically synthesized oxidized polymer that is not doped with an anion in the above-mentioned organic solvent, and adding a dopant to this solution. It is not limited to this method.

The dopant-containing oxidized polymer 81 degrees of the aniline derivative in the polymer solution is not particularly limited, but is usually used in the range of 0.01 to 90% by weight.

Solid electrolytes and solid electrolytic capacitors can be manufactured by coating or spraying the thus obtained polymer solution on a dielectric film, and then by removing the organic solvent. . The method for removing the organic solvent is not particularly limited, and methods such as vacuum degassing, heat drying, air drying, etc. that are commonly used by those skilled in the art can be used.

In this way, the electric conductivity of the solid electrolyte ``j'Xit, i<I, is in the range of 10<-2> to 10<2> S/cm.

Although the dielectric used in the present invention is not particularly limited, for example, known porous metal oxides such as aluminum, tantalum, and niobium can be used.

[Effect of the invention 1] The solid electrolytic capacitor obtained by the present invention has significantly superior performance in terms of capacity, dielectric loss, and stability over time compared to conventional solid electrolytic capacitors using non-e1 oxide semiconductors or organic semiconductors. have.

Furthermore, the solid electrolytic capacitor of the present invention has the following advantages compared to conventionally known solid electrolytic capacitors.

■ Since the electrolyte layer can be formed without high-temperature heating, there is no damage to the oxide film on the anode, making it easy to repair.
There is no need to perform conversion (reconstitution).

Therefore, the rated voltage can be increased several times compared to conventional capacitors, and the shape can be made smaller to obtain a capacitor with the same capacity and rated voltage.

■Low leakage current.

■ Capacitors with high withstand voltage can be manufactured.

■ Since the conductivity of the electrolyte is sufficiently high at 10-2 to 102 S/Cm, there is no need to provide a conductive layer such as graphite. This simplifies the process and is advantageous in terms of cost.

[Examples] Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Example 2 - Polymerization of prepared aniline 201d and 0.35 mol of 2.5-dimethoxyaniline were placed in a glass reaction vessel, An aqueous solution with pH<1.0 was prepared.

In this aqueous solution, each electrode has an area of 10 cm at intervals of 2 cm.
After inserting the two platinum electrodes #i, electrolytic oxidation polymerization was carried out for 4 r by flowing electricity of 20 coulombs under stirring.

At this time, a black oxidized polymer was deposited on the platinum electrode of the anode. After the electrolytic polymerization was completed, the coated anode was washed with distilled water and vacuum dried at 70°C. Next, the polymer was peeled off from the platinum electrode and dissolved in at + -nitrile to prepare a polymer solution with a polymer temperature of 2%. The obtained polymer solution was coated on a glass plate for 11 seconds, and then degassed under vacuum to prepare a sintering film. The electrical conductivity of this film at room temperature (DC four-terminal method) is 2.5x 1Q-
i 81 cm, and elemental analysis revealed that it was 2,5-lame 1 to xyani 921. According to the infrared spectrum and N M r<, this polymer contained 80 mol % or more of repeating units having the structure of general formula (2). 1 Place the smoothed film in the air.
pri, 'at'i, □06. Etokoro, 2. '2
X 10-I 81 cm, showing almost no electric type conductivity.

It hadn't changed at all.

11゛Concern 1゛1 σ1 thickness 1007
1H aluminum foil (purity 99.99%) was used as an anode and the surface of the foil was electrochemically etched using alternating direct current and alternating current.
It was made into a porous aluminum foil of TIt/g. The etched aluminum foil was then immersed in an ammonium borate solution, and a thin dielectric layer was electrochemically formed on the aluminum foil in the solution.

The polymer solution was applied to the surface of this dielectric, and then the acetonyl-1-lyl solvent was removed under reduced pressure to produce a solid electrolytic capacitor. Characteristics were measured using aluminum foil as the cathode and sealing it with rubber. The results are shown in the table.

Comparative example

Claims (1)

[Claims] General formula (1) ▲ Numerical formulas, chemical formulas, tables, etc. It is an alkoxy group. However, all of R_1 to R_4 are not hydrogen atoms at the same time. ) A solid electrolytic capacitor characterized by using a dopant-containing oxidized polymer of an aniline derivative as a solid electrolyte.