Characterisation of activated nanoporous carbon for supercapacitor electrode materials

Commercial nanoporous carbon RP-20 was activated with water vapor in the temperature range from 950 degrees C to 1150 degrees C. The XRD analysis was carried out on nanoporous carbon powder samples to investigate the structural changes (graphitisation) in modified carbon that occurred at activation temperatures T >= 1150 degrees C. The first-order Raman spectra showed the absorption peak at 1582 cm(-1) and the disorder (D) peak at 1350 cm(-1). The low-temperature N-2 adsorption experiments were performed at -196 degrees C and a specific surface area up to 2240 m(2)g(-1) for carbon activated at T= 1050 degrees C was measured. The cell capacitance for two electrode activated nanoporous carbon system advanced up to 60 F g(-1) giving the specific capacitance similar to 240 F g(-1) to one electrode nanoporous carbon vertical bar 1.2 M (C2H5)(3)CH3NBF4 + acetonitrile solution interface. A very wide region of ideal polarisability for two electrode system (similar to 3.2 V) was achieved. The low frequency limiting specific capacitance very weakly increases with the rise of specific area explained by the mass transfer limitations in the nanoporous carbon electrodes. The electrochemical characteristics obtained show that some of these materials under discussion can be used for compilation of high energy density and power density non-aqueous electrolyte supercapacitors with higher power densities than aqueous supercapacitors. (C) 2007 Elsevier Ltd. All rights reserved.