Nickel catalytic graphitized porous carbon as electrode material for high performance supercapacitors

Whey-protein-derived nitrogen-doped porous carbon has been prepared by preliminary carbonization at 400 °C and final KOH activation at 700 °C combined with catalytic graphitization. Physical characterization indicated that the nitrogen-doped activated electrode material had a large specific surface area (2536 m² g^-1) and plenty of interconnected cavities, which greatly improved the performance of supercapacitors. Electrochemical measurements demonstrated that the as-prepared activated electrode material had exceptionally high capacitance of 248 F g^-1 at charge/discharge current density of 0.1 A g^-1. Moreover, the prepared supercapacitors exhibited ideal capacitive behavior with nearly no capacitance loss in 6 mol L^-1 KOH at different charge/discharge current densities ranging from 0.1 to 5 A g^-1 after 1000 charge/discharge cycles. The derived energy density was 12.4 Wh kg^-1 at a power density of 495 W kg^-1 under operational conditions. These results suggested that the whey-protein-derived porous carbon is a promising supercapacitor electrode material.