N-doped porous carbon derived from walnut shells with enhanced electrochemical performance for supercapacitor

As the low-cost, natural multi-component for elemental doping and environment-friendly characteristics, biomass-derived porous carbon for energy storage attracts intense attention. Herein, walnut shells-based porous carbon has been obtained through carbonization, hydrothermal and activation treatment. The corresponding porous carbon owns superior electrochemical performances with specific capacitance reaching up to 462F g(-1) at 1 A g(-1), and shows excellent cycling stability (5000 cycles, similar to 94.2% of capacitance retention at 10 A g(-1)). Moreover, the symmetry supercapacitor achieves high specific capacitance (197 F g(-1) at 1 A g(-1)), relevant electrochemical cycling stability (5000 cycles, 89.2% of capacitance retention at 5 A g(-1)) and high power/energy density (42.8W h kg(-1) at 1249 W kg(-1)). Therefore, the facile synthesis approach and superb electrochemical performance ensure that the walnut shells-derived porous carbon is a promising electrode material candidate for supercapacitors.