Synthesis and processing optimization of N-doped hierarchical porous carbon derived from corncob for high performance supercapacitors

In this paper, N-doped hierarchical porous carbon-based supercapacitor electrode materials have been synthesized by means of pyrolysis methods using corncob, KOH and urea as biomass sources, activator and nitrogen source, respectively. The influence of carbonization temperature on the morphology and structure and N doping content on supercapacitor performance of corncob derived porous carbons has been investigated systematically. The specific capacitance of sample with carbonization temperature at 800 °C and urea: corncob mass ratio of 4:3 reaches 382.6 F/g at 0.5 A/g, and still maintains as high as 232.7 F/g at high current density of 20 A/g. The symmetric supercapacitor achieves a high energy density of 18.84 Wh/kg at power density of 149.36 W/kg in 6 M KOH aqueous electrolyte. It also shows excellent cycling stability with a 95.16% capacitance retention after 10,000 cycles. The results demonstrate that these as-prepared corncob-derived activated carbons have a great prospect in low-cost and high-performance supercapacitors.