The effect of the HClO4 oxidization of petroleum coke on the properties of the resulting activated carbon for use in supercapacitors

Petroleum coke (PC) was modified by HClO4 oxidization. Activated carbons (ACs) were prepared using a mass ratio of KOH/modified PC of 3:1 (denoted OAC-3) and a KOH/PC mass ratio of 4:1 (denoted AC-4) for comparison. XRD, I2 adsorption, N2 adsorption and cyclic voltammograms were used to investigate the influence of HClO4 oxidization on the structure of the PC and the performance of the resultant AC. Results indicated that HClO4 oxidization increased the d(002) of microcrystalline PC from 0.344 to 0.353 nm and decreased Lc from 2.34 to 1.75 nm. The specific surface areas of AC-4 and OAC-3 were 2 929 and 3 058 m2/g, respectively. AC-4 and OAC-3 had a specific gravimetric capacitances of 361.3 and 392.7 F/g at a scan rate of 0.5 mV/s, respectively. A supercapacitor based on OAC-3 possessed a better power performance than that based on AC-4.