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

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.