Biomass-derived S, P, Cl tri-doped porous carbon for high-performance supercapacitor

High-performance porous carbon materials have always received much interest for supercapacitors due to their excellent cycling stability, superior conductivity, etc. Herein, sulfur, phosphorous and chlorine tri-doped hierarchically porous carbon (SPC) were prepared by simply co-activating using KOH and Na 2 S with wheat bran as precursor. Na 2 S can not only improve the specific surface area (1310.3 m 2 g −1 to 1585.5 m 2 g −1 ) and pore volume (0.767 cm 3 g −1 to 0.977 cm 3 g −1 ), but also introduce sulfur atoms to contribute extra pseudocapacitance. Benefitting from the heteroatom doping and surface structure optimizing, the as-prepared SPC exhibits a large specific capacitance of 488 F g −1 (at 1 A g −1 ), superior to the porous carbon that was only activated by KOH (245 F g −1 at 1 A g −1 ), and still remains 51.6% of the initial specific capacitance at 20 A g −1 .The supercapacitor assembled by SPC delivers a high energy density of 12.5 Wh kg −1 (at 250 W kg −1 ). After charge-discharge for 9000 cycles (at 10 A g −1 ), the capacitance can still remain 96% of the initial value, showing that SPC is a promising candidate for high-performance supercapacitor. • S, P, Cl tri-doped porous carbon was successfully prepared via KOH and Na 2 S co-activation. • The co-activation method can improve the specific surface area, pore volume, and S content of the as-obtained carbon. • The as-prepared SPC exhibits considerable pseudocapacitance contribution. • Symmetric supercapacitor constructed by the optimized SPC delivers high energy density and long term cycling stability.