Carbon nanotubes with arylsulfonic acid groups were prepared using azobisisobutyronitrile as an initiator via the surface modification of carbon nanotubes by aminobenzenesulfonic acid in fuming sulfuric acid. The electrochemical performances of the functional multi-wall carbon nanotubes used as active electrode materials were tested with cyclic voltammetry and galvanostatic charge-discharge. The results show that the functional multi-wall carbon nanotubes electrodes exhibit larger capacitance. The specific capacitance has been enchanced up to 50 F·g-1 at 3 mA discharging compared to that of carbon nanotubes coped with fuming sulfuric acid (22 F·g-1 at 3 mA) and carbon nanotubes without treatment (15 F·g-1 at 3 mA).
