Carbon nanofibre/hydrous RuO2 nanocomposite electrodes for supercapacitors

Amorphous RuO2 center dot xH(2)O and a VGCF/RuO2 center dot xH(2)O nanocomposite (VGCF=vapour-grown carbon fibre) are prepared by thermal decomposition. The morphology of the materials is investigated by means of scanning electron microscopy. The electrochemical characteristics of the materials, such as specific capacitance and rate capability, are investigated by cyclic voltammetry over a voltage range of 0-1.0 V at various scan rates and with an electrolyte solution of 1.0 M H2SO4. The specific capacitance of RuO2 center dot xH(2)O and VGCF/RuO2 center dot xH(2)O nanocomposite electrodes at a scan rate of 10 mV s(-1) is 410 and 1017 F g(-1), respectively, and at 1000 mV s(-1) are 258 and 824 F g(-1), respectively. Measurements of ac impedance spectra are made on both the electrodes at various bias potentials to obtain a more detailed understanding of their electrochemical behaviour. Long-term cycle-life tests for 10(4) cycles shows that the RuO2 center dot xH(2)O and VGCF/RuO2 center dot xH(2)O electrodes retain 90 and 97% capacity, respectively. These encouraging results warrant further development of these electrode materials towards practical application. (C) 2007 Elsevier B.V. All rights reserved.