Microstructure and electrochemical double-layer capacitance of carbon electrodes prepared by zinc chloride activation of sugar cane bagasse

Activated carbons for supercapacitor electrodes were prepared from sugar cane bagasse using chemical activation with ZnCl2. The ZnCl2 activation of bagasse was studied using thermogravimetic analysis and the carbon pore structures were characterised using N2 and CO2 adsorption. In two-electrode sandwich type supercapacitor cells containing 1 M H2SO4 the sugar cane bagasse carbons (SCCs) exhibit energy densities up to 10 Wh kg-1 and specific capacitance close to 300 F g-1. The electrochemical performance of the SCCs is attributed to high specific surface areas and the development of mesopores with ZnCl2 impregnation ratios of 1 or greater. In contrast, the pyrolysis of bagasse without ZnCl2 produces a carbon with low specific capacitance. The SCC prepared with a ZnCl2 ratio of 3.5 shows the most stable electrochemical performance at fast charge-discharge rates. Copyright © 2009 Elsevier B.V. All rights reserved