Oxygen-doped activated carbon fiber cloth as electrode material for electrochemical capacitor

Novel oxygen-doped activated carbon fiber cloths (OACFC), with different compositions of surface oxygen functionalities, have been prepared by direct electrooxidative/reductive methods in an undivided electrolytic cell filled with high purity water without a supporting electrolyte under high voltage conditions. The morphology and surface chemical composition of the materials have been investigated by SEM, Raman and XPS spectroscopies. They revealed an electrochemical erosion of the CF surface upon activation, concomitant with a strong change of the D/G ratio of characteristic Raman bands and the surface O/C atomic ratio, respectively. Thus pretreated material was tested as electrodes for an electrochemical capacitor by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 3.75 M H2SO4. The performance of the electrochemical capacitor based on modified carbon electrodes was compared to that of an analogous device with unmodified carbon. The measurements revealed altered electrochemical behavior of the OACFC in terms of the determined capacitances. The proposed activation method is also superior to other electrochemical activation procedures, since it uses much less energy per CF surface or mass.

► An efficient elctrochemical activation of carbon fiber cloth can be achieved by electrochemical activation in the absence of supporting electrolyte (deionized water).
► The activated material shows superior performance as electrode for electrochemical capacitor.
► The activation procedure is clean and requires small energy to proceed.