Fabrication of N/O self-doped hierarchical porous carbons derived from modified coal tar pitch for high-performance supercapacitors

Carbon materials with hierarchical porous architecture and high conductivity are highly desired for supercapacitors (SCs), but there is a daunting challenge to prepare them via an ecofriendly and economic route. Herein, a co-activation/graphitization strategy with the aid of KOH and Ni is proposed to fabricate the N/O self-doped hierarchical porous carbons (HPCs), employing coal tar pitch (CTP) modified by fluid catalytic cracking oil as a low-cost precursor. The as-prepared HPCs with a large specific surface area of 2254 m2 g−1 and appropriate heteroatom doping exhibit a specific capacitance of 368 F g−1 of specific capacitance at 0.5 A g−1 and still retain 270 F g−1 at 20 A g−1 (73.3% capacitance retention rate) in 6 M KOH electrolyte. Besides, the symmetrical SC achieves a maximum energy density of 27.45 Wh kg−1 at a power density of 253 W kg−1 in 1 M Na2SO4 electrolyte. This work designs a novel route for preparing electrode materials with excellent electrochemical performance and provides a feasible way for the value-added utilization of low-cost CTP.