Nitrogen, sulfur co-doped hierarchically porous carbon from rape pollen as high-performance supercapacitor electrode

Fabrication of porous carbon from biomass offers a possibility of the practical application of carbonaceous materials. Herein, a nitrogen, sulfur-codoped hierarchically porous carbon (RPHPC) with inherited morphology/microstructure derived from rape pollen is fabricated by direct activation of rape pollen with mixed salts of ZnCl2 and FeCl3 for supercapacitors. Originating from the synergetic effect of interconnected, hierarchical pore structure with the inherited spherical morphology, abundant surface opened channels and appropriate amount of doped N, S atoms with proper degree of graphitization, the resultant hierarchically porous carbon displays a high specific capacitance of 361.6 F g(-1) at a current density of 1 A g(-1) and outstanding rate capability (217.0 F g(-1) at 100 A g(-1)). Significantly, the assembled RPHPC-750//RPHPC-750 symmetrical device delivers a high energy density of 32.2 Wh kg(-1) at a power density of 0.089 kW kg(-1) and retain an energy density of 10.7 Wh kg(-1) even at 4.1 kWkg(-1). In addition, it also exhibits superior cycling stabilty with 94.5% capacitance retention after 20,000 cycles at 5 A g(-1). Such remarkable results may offer a new perspective to develop high-performance carbon materials from biomass for supercapacitor applications. (C) 2019 Elsevier Ltd. All rights reserved.