JPH0473606B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to an electrolytic capacitor with an improved solid electrolyte. Prior Art Most conventional solid electrolytic capacitors have solid electrolytic capacitors in which a solid electrolyte is interposed between an anode electrode made of a valve metal having an anodized film on its surface and a cathode electrode configured to face the anode electrode. Manganese dioxide has been used as a solid electrolyte. Problems to be Solved by the Invention However, when manganese dioxide is formed on an electrode, it is generally immersed in a manganese nitrate solution and then thermally decomposed, which causes damage to the anodic oxide film and, in addition, anodization with manganese dioxide. There was a problem that the repairability of the film was poor. Means for Solving the Problems In order to solve the above-mentioned problems, the present invention aims to provide a gap between an anode electrode made of a valve metal having an anodic oxide film on its surface and a cathode electrode configured to face the electrode. This solid electrolytic capacitor is characterized in that an organic semiconductor compound consisting of 5-phenothiazine and 7,7,8,8 tetracyanoquinodimethane is used as the intervening electrolyte. Function Characteristics as a donor material include a moderately small activation energy, a large π-electron system that forms a stable resonant structure, and a high polarizability. Satisfying all of these conditions is an important factor in the molecular design of the donor material, and in order to apply the complex to electrolytic capacitors, there is a problem with adhesion to the electrodes, so it is necessary to use complexes with extremely fine crystal grains. 7, 7, 8, 8 tetracyanoquinodimethane (hereinafter referred to as TCNQ), which has good compatibility with metal oxides, is desirable. Furthermore, a TCNQ complex is required whose electrical conductivity does not change much from low to high temperatures and does not easily decompose even at high temperatures. Therefore, the present inventors have repeatedly conducted various studies and found a TCNQ donor material that satisfies the above requirements as much as possible. Phenothiazine 5-niums have the following structure, and the S atom is ionized. Here, when X is NH ₂ , it is bis(amide)phenothiazine 5-nium, when X is N(CH ₃ ) ₂ , it is bis(dimethylamide)phenothiazine 5-nium, and when X is a halogen, for example, Cl, it is bis(chloro ) Phenothiazine 5-nium, X is NH (CH ₃ )
Bis(methylamide)phenothiazine 5 for
It has become clear that both can be used as solid electrolytic capacitors. Since the phenothiazine 5-niums are ionized, the activation energy for donating electrons is moderately small, and the polarizability is very large because the S atoms are ionized, so the electrons are localized. Furthermore, since the π electrons have benzene nuclei on both sides, resonance is stabilized even after the S atoms are ionized. Furthermore, by adding an electron-donating group to a substituent, the molecule has a molecular structure that easily donates electrons. Since it is a polynuclear heterocyclic compound, it is extremely thermally stable. The electrical conductivity was very good, and the conductivity of pellets compressed at 400 kg/cm ³ at room temperature was 14 Ω ^-1 cm ^-1 . Examples Specific examples of the present invention will be described below. As an electrode, an aluminum foil etched with a surface magnification of about 10 times was subjected to 80V chemical conversion using an ammonium phosphate solution and thoroughly dried. Next, bis(dimethylamide)phenothiazine 5-nium (TCNQ) ₂ complex was dissolved in acetonitrile by heating to create a saturated solution, and the solution was coated on the electrode.
The solvent, acetonitrile, was scattered and removed by heating at 90°C. This operation was repeated three times, colloidal carbon was applied and dried as a cathode, and then silver paste was applied and lead wires were soldered and packaged to prepare a capacitor sample (sample group A). For comparison, as a conventional example, a saturated solution was prepared by dissolving manganese nitrate in water, and the above electrode was immersed in the solution and dried at 400°C for 5 minutes.
I repeated it. The cathode and lead wires were attached as described above, and a capacitor sample (sample group B) was prepared in the same manner. All ratings are 50WV−2.2μF
And so. Initial characteristics of these two types of capacitors and 105
Tables 1 and 2 show reliability data (high temperature load test) in which the rated voltage was applied for 2000 hours in a ℃ atmosphere. Capacitance and tanδ are values at room temperature 120Hz,
Leakage current shows the value after 1 minute of applying the rated voltage at room temperature.

【table】

[Table] Note that the anode electrode of the present invention is not limited to aluminum foil, and can also be applied to other metals or powder sintered electrodes, which are included in the technical scope of the present invention. Effects of the invention As described above, phenothiazine 5-nium
The solid electrolyte made of the TCNQ complex quickly bonds with the electrode without damaging the oxide film, exhibits excellent characteristics as a capacitor, and is also extremely reliable, significantly improving the characteristics of solid electrolytic capacitors. It also stabilizes and has great industrial and practical value.

Claims (1)

[Claims] 1. An electrolyte having the structural formula shown below as an electrolyte interposed between an anode electrode made of a valve metal having an anodized film on its surface and an anode electrode configured to face the anode electrode. A solid electrolytic capacitor characterized by using an organic semiconductor compound consisting of phenothiazine 5-nium and 7,7,8,8 tetracyanoquinodimethane.