Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte

摘要

The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4 F/m~2 in 18M H_2SO_4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however, gave a featureless cyclic voltammogram in 18 M H_2SO_4 solution. In the case of exfoliated natural graphite, the intercalation of H_2SO_4 molecules is evidenced by redox peaks observed in the voltammograms in the same conditions. Therefore, a strong interaction between the H_2SO_4 molecules and the ExCF surface might be the reason for the origin of pseudo-capacitance with ExCF in H_2SO_4 electrolyte.