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 462[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text], and shows excellent cycling stability (5000 cycles, [Formula: see text]94.2% of capacitance retention at 10[Formula: see text]A[Formula: see text]g[Formula: see text]). Moreover, the symmetry supercapacitor achieves high specific capacitance (197[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text]), relevant electrochemical cycling stability (5000 cycles, 89.2% of capacitance retention at 5[Formula: see text]A[Formula: see text]g[Formula: see text]) and high power/energy density (42.8[Formula: see text]W[Formula: see text]h[Formula: see text]kg[Formula: see text] at 1249[Formula: see text]W[Formula: see text]kg[Formula: see text]). 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.