IMPROVEMENT OF HEAVY-DRAIN DISCHARGE PROPERTIES OF POLYPYRROLE CATHODE BY THE ELECTRO-CODEPOSITION OF CARBON POWDER

Homogeneous codeposition of polypyrrole and carbon powder was examined to obtain a cathode having more improved characteristics for lithium secondary battery. Codeposition by anodization was performed directly on a stainless-steel net from suspension of carbon powder in propylene carbonate (PC) containing 0.2 M pyrrole monomer and 1 M LiClO4. Obtai ned codeposited-active materials showed favorably improved characteris tics as a cathode in 1 M LiClO4/PC electrolyte. Cyclic voltammograms o f the obtained composite gave steep current peak having fairly increas ed height and the cathodic peak was shifted positively, indicating a r eduction of the overpotential. These features imply that the codeposit ed material is suitable for high current charge/discharge of Li second ary battery, which was also ascertained by the constant current charge /discharge test. The capacity increase was roughly proportional to the specific surface area of the carbon powder in the deposits. Scanning electron microscopy (SEM) pictures supported the surface-enlargement m echanism for the codeposit material.