HIGH CHARGE-DENSITY CONDUCTING POLYMER GRAPHITE FIBER-COMPOSITE ELECTRODES FOR BATTERY APPLICATIONS

Novel composite electrode structures have been fabricated by single-st ep electropolymerization of polypyrrole onto a porous graphite fiber m atrix. The graphite substrate provides a lightweight structure with hi gh surface area. The available charge capacity of the composite electr odes was proportional to the electropolymerization merization time and the mass of electroactive polymer with reversible charge capacities i n excess of 4.0 C cm(-2) and aspecific capacity of 90 mAh g(-1), indep endent of polymer mass. The rate of charge extraction was dependent on the polymer mass and the morphology of the polymer electrode. In test cells using a polypyrrole/graphite fiber anode and a polypyrrole-poly styrene sulfonate/graphite fiber cathode, we have demonstrated a capac ity of more than 40 mAh g(-1) based on the active mass of the undoped polymer on discharging the cell to 0.1 V over a 10 k Omega load. More than 70% of the available charge was extracted from the cell over 50 c ycles with no degradation of cell performance.