Multi-heteroatom-doped porous carbon with high surface adsorption energy of potassium derived from biomass waste for high-performance supercapacitors

Sustainable and renewable biomass-derived porous carbon (BPC) have garnered considerable attention owing to their low cost, high specific surface area, and outstanding electrochemical performance. However, the subpar energy density severely restricts the applications of BPC in high-energy-density devices. Herein, a high-surfacearea porous carbon with multiple heteroatoms doping was derived from rapeseed meals by hydrothermal carbonization and high-temperature activation. The rapeseed meal-derived activated carbon (RMAC) exhibits a remarkable surface area of 3291 m2 g  1 and is doped with nitrogen (1.05 at.%), oxygen (7.4 at.%), phosphorus (0.31 at.%), and sulfur, resulting in an impressive specific capacitance of 416 F g  1 at 1 A g  1. Furthermore, even after 10,000 cycles, the optimized RMAC-800 electrode maintains 92 % of its initial capacitance, attesting to its exceptional performance. Through comprehensive density functional theory (DFT) calculations, the elements O, N, P, and S can significantly enhance the electron negativity and density, improving the adsorption and diffusion of K+ to attain a high capacitance. To assess the RMAC-800's practical performance, an asymmetric supercapacitor with 1 M [BMIM]BF4/AN electrolyte was produced that delivered a high energy density of 195.94 Wh kg  1 at a power density of 1125 W kg  1. Thus, we propose an eco-friendly strategy for producing BPC materials with outstanding electrochemical performance for supercapacitors.