The charge-discharge capability of a polymer composite cathode prepared from 2,5-dimercapto-1,3,4-thiadiazole (DMcT), polyaniline, 3-alkylcarboxylate-4-methylpyrrole, and acetylene black has been investigated on different kinds of current collectors including copper, nickel, aluminum, and titanium foil, gold-plated titanium foil, and a porous carbon Blm in a lithium cell system with a gel-like polymer electrolyte. The polymer composite cathode with a copper current collector provides a relatively flat discharge potential difference (3.4 to 2.8 V) and high current capability (137 mA/g-cathode) without undue deterioration of the energy density. The battery can be charged up to 550 mWh/g-cathode within 1.25 h, and it can be reversibly discharged within 1.25 h. This unique charge-discharge performance might be attributed to the redox reaction of a copper(I or II)-DMcT complex which is formed in the first several cycles as a result of oxidative dissolution of copper. The use of a thin copper current collector in place of a rather thick porous carbon film enables us to fabricate polymer lithium rechargeable batteries with a thin-film configuration.