Rechargeable Lithium Batteries Using Polypyrrole–Poly(styrenesulfonate) Composite as the Cathode-Active Material

Abstract

Abstract Polypyrrole–polyelectrolyte composite, obtained by electrochemical polymerization on a vapor-grown carbon fiber (VGCF) electrode, was used as a cathode-active material for a rechargeable lithium battery. Poly(styrensulfonate) ion was suitable as a dopant in terms of rechargeability of the battery. The VGCF, which has a fibrous structure, was effective as a current collector for the polymer electrode. The content of the dopant calculated by the molar ratio of sulfur and nitrogen was ca. 30%. The open-circuit voltage was 3.55 V at the time. A charge–discharge, accompanied by an Li+ deinsertion–insertion of the composite, was observed. The chargedischarge mechanism is similar to that of inorganic cathode-active materials that show Li+ intercalation. The battery was cycled stably beyond 30 times between 3.66 and 1.50 V at a constant current of 0.889 mA cm−2. An experimental capacity of 57 Ah kg−1 was obtained at the largest value on the basis of the weight of the active material. There is a possibility of developing a light-weight rechargeable battery using the polypyrrole–poly(styrenesulfonate) composite.