An Organosulfur Polymer Cathode with a High Current Capability for Rechargeable Batteries

The charge‐discharge capability of a polymer composite cathode prepared from 2,5‐dimercapto‐1,3,4‐thiadiazole (DMcT), polyaniline, S‐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 film 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.