Electrochemical Performance of Graphene Nanosheets as Electrode Material for Supercapacitors

Graphene nanosheets (GNSs) were prepared from flake natural graphite by oxidation, rapid expansion and ultrasonic treatment. The morphology, structure and electrochemical performance of GNSs as electrode materials for supercapacitors were systematically investigated via high-resolution transmission electron microscopy, X-ray diffraction, nitrogen adsorption and desorption isotherms and a variety of electrochemical testing techniques. The electrodes with freestanding GNSs prepared by coating method exhibited good rate capability and reversibility at high scan rates in electrochemical performances. GNS electrode with specific surface area of 243 m(2) g(-1) maintained a stable specific capacitance of 200 F g(-1) under specific current of 0.1 A g(-1) for 500 cycles of charge/discharge.