Preparation and electrochemical performance of petroleum coke-based superactivated carbons as electrodes of supercapacitors

A series of petroleum coke-based superactivated carbons (SACs) was prepared by KOH activation. Electrochemical performance of the SACs and a porous carbon called YP15 (Kuraray Chemical Co., Japan) as electrodes of supercapacitors in aqueous and non-aqueous electrolytes were characterized and compared by chronopotentiograms, cyclic voltammetry and AC impedance spectrum analysis. It was found that the specific capacitances of SACs increased with surface area and the highest values in the electrolytes of KOH, H_2SO_4, (C_2H_5)_4NBF_4/propylene carbonate(PC), and (C_2H_5)_4NBF_4/acetonitrile, were 257F/g, 228F/g, 140F/g and 142F/g respectively, all greater than that of YP15. The ESR volume resistivities of the SACs were lower than that of YP15 in 1mol/L H_2SO_4, higher than that of YP15 in 1mol/L (C_2H_5)_4NBF_4/PC, and close to that of YP15 in 3mol/L KOH. The ESR volume resistivity of the SACs in 1mol/L (C_2H_5)_4NBF_4/acetonitrile, which was prepared at 800℃ for 3h using a KOH to petroleum coke ratio of 4∶1, was lower than that of YP15.