Electrochemical behavior of exfoliated carbon fibers in H2SO4 electrolyte with different concentrations

Exfoliated carbon fibers (ExCFs) were prepared by the decomposition of intercalation compounds with nitric acid derived from pitch-based carbon fibers and used as electrodes of electrochemical capacitors in sulfuric acid electrolyte. The specific capacitance, which was estimated by cyclic voltammetry and galvanostatic charge-discharge (CD) measurements, increased gradually with the concentration of the electrolyte up to10 mol/dm3 and then rapidly to huge value in higher concentration of electrolyte. The capacitance obtained for a sample with the largest specific surface area (ca. 300 m2/g) was 450 F/g, which was calculated from the 50th discharge curve of CD experiment. The results suggest the possibility of pseudo-capacitance by the intercalation of sulfuric acid molecules into graphite gallery of ExCFs electrode. [Copyright &y& Elsevier]