Electrocapacitive properties of nitrogen-containing porous carbon derived from cellulose

A generalised approach to the preparation of nitrogen-containing porous carbon from cellulose for supercapacitor applications is demonstrated in this paper. A sample prepared at a carbonisation temperature of 600 °C with a specific surface area of 781 m2 g−1 and a pore volume of 0.68 cm3 g−1 displayed the best electrocapacitive performance. The well-developed porous structure coupled with the presence of nitrogen-containing functional groups along with nascent hydrogen enabled this sample to exhibit specific capacitances of 248 and 133 F g−1 at current densities of 0.1 and 10 A g−1, respectively, in a symmetric cell with 1 M aqueous H2SO4 solution as the electrolyte. With this electrode, about 89% of the initial capacitance is retained after 2000 cycles at a current density of 1 A g−1. A symmetric supercapacitor fabricated using this carbon in both electrodes exhibits an energy density of 14.6 Wh Kg−1 at a power density of 63.5 W Kg−1 and remains at 7.9 Wh Kg−1 at a power density of 6500 W Kg−1.