Abstract: Disclosed is a method for forming an aluminum oxide film of a large surface area on an electrode for a high voltage electrolytic capacitor. In accordance with the method, an oxide film of a uniform thickness is formed, prior to a process of etching the oxide film. A re-anodization is then partially conducted for an etched portion of the oxide film. The resultant oxide film has an increased surface area. The method of the invention makes it possible to prepare a dielectric oxide film having characteristics of a uniform thickness and a large surface area. In accordance with the invention, it is possible to expect an increase in the capacitance of electrolytic capacitors.

Abstract: A method for making an electrode for lithium secondary cells. Lithium and cobalt ions are co-precipitated in an alkaline solution in such a way that the ratio of the former to the latter is 1.05:1 or more and then, are thermally treated to give LiCoO2 powder. This ternary system compound is combined with a current collector and a binder. The electrode has an initial discharge capacity of 160 mAh/g and retains 90% of the initial capacity even after 400 times of charge/discharge cycle.