EVALUATION OF ACTIVATED CARBON ELECTRODES FOR ELECTRIC DOUBLE-LAYER CAPACITORS USING AN ORGANIC ELECTROLYTE SOLUTION

Double layer capacitances of PTFE-bonded carbon sheet electrodes comprising various activated carbons were evaluated in (C2H5) 4PBF4/propylene carbonate solution for use as an electrode of electric double layer capacitors. The electrodes had appropriate porosities to reserve the electrolyte and good electric conductivities. The volumetric capacitance of the electrode and gravimetric capacitance of actived carbon were estimated as a function of BET surface area of activated carbon. The true double layer capacitance on these activated carbon electrodes was calculated to be 4.6-mu-F/cm2. The deterioration of an coin cell type capacitor during the voltage application was found to be closely related to the oxygen content of activated carbon used in the electrode.