Influence of Chemical Modification of Activated Carbon Surface on Performance of Supercapacitors

Abstract

In order to improve capacitance in supercapacitors application, activated carbon (AC) was modified by nitric acid oxidizing treatment. Oxygen-containing functional groups (OCFG) were detected by using FTIR techniques. Cyclic voltammetry and constant current charge-discharge were used to characterize the electrochemical performance of the samples in 6 mol/L KOH solution. FTIR studies showed that chemical modification promoted the formation of OCFG on the surface of AC. It was found that the contribution rate of pseudo-capacitance to the total capacitance increased significantly with the extent of oxidization treatment. When oxidized by 50% HNO3, AC achieved a specific capacitance of 197.26F/g at a current density of 20mA/cm2 corresponding to an increasing rate up to 20%.