Toshikuni Kojima

An aluminum solid electrolytic capacitor with an electroconducting-polymer electrolyte

Abstract A new type of aluminum solid electrolytic capacitor in which electroconducting polymer is applied as an electrolyte was developed. It was found that polypyrrole doped with alkylnaphthalenesulfonate (PPy/ANS) offers excellent thermal and moisture stabilities. By providing an etched and anodized aluminum foil electrode with a thin layer of pyrolytic manganese dioxide, higher coverage with electrochemically synthesized polypyrrole was accomplished. The newly developed capacitor not only has good frequency and temperature characteristics but also has good thermal and moisture stabilities.

Covering anodized aluminum with electropolymerized polypyrrole via manganese oxide layer and application to solid electrolytic capacitor

A new technology for covering an etched and anodized aluminum (Al) foil with polypyrrole (PPy) was developed. PPy was electropolymerized from an external electrode via an extremely thin semiconducting manganese oxide layer prepared on the etched and anodized Al foil in advance. Pyrolytic and reduced manganese oxide could be used with little difference in the performance of the PPy layer growth. To obtain a high coverage ratio, the optimal starting materials were manganese nitrate for the pyrolysis process and sodium permanganate for the reduction process. On the basis of the technology, two kinds of Al solid electrolytic capacitors, in which the PPy layers are used as electrolytes, were produced and characterized. These capacitors showed almost equal ideal impedance-frequency characteristics, excellent temperature characteristics and environmental stability, and independence of the manganese oxide synthesis route.

Effects of mono-substituted phenol additives on the electrical and mechanical properties of electrochemically synthesized polypyrrole

Abstract Polypyrrole (PPy) which is electrochemically synthesized with a mono-substituted phenol additive has enhanced conductivity, thermal stability and tensile strength. From elemental analysis data, mass spectra and FT-IR spectra, there is no obvious evidence that the additive is incorporated in PPy. Electronic absorption spectra and laser Raman spectra show that the additive reduces the polaron peak and enhances the bipolaron peak. The increased structural regularity is considered to be the reason for the improvement of the electrical and mechanical properties.