Oxygen functional groups were removed from activated carbon in order to improve the electrochemical supercapacitor performance. Commercially available and surface-modified activated carbon electrodes were compared in non-aqueous electrolyte, which allowed stable experimentation at high voltages. N2-adsorption, FT-IR, and elemental analyzer were used to characterize the surface areas, pore volumes, surface chemical compositions, and oxygen content. Surface area and oxygen content were decreased by heat-treatment at high temperature. Despite the decreased surface area, both of the commercially available and surface-modified activated carbons showed similar specific capacitance of 18.6 Fcc-1 and 18.2 Fcc-1, respectively. Also electrochemical impedance spectra, stability at high voltage and cycle performance showed that surface-modified activated carbon had outstanding electrochemical performance due to the decrease in oxygen content of the commercial activated carbon.

Keywords: Supercapacitor, Activated carbon, Surface-modified activated carbon.