Solid electrolytic capacitors using an aluminum alloy electrode and conducting polymers

Solid electrolytic capacitors, in which an aluminum–zirconium (Al–Zr) alloy foil is used as an electrode and a composite conducting polymer layer as a counter-electrode, were prepared and investigated. Soluble polyaniline (PAn) doped with carboxylic acid was used as a conductive precoating layer; using the precoating layer as an anode a polypyrrole layer was formed by electrochemical polymerization to form a composite conducting polymer layer. This method was successfully used in forming the counter-electrode of new alloy electrode capacitors. The capacitors show high capacitance per unit area and excellent high-frequency performance.