Preparation of nitrogen and phosphorus Co-doped porous carbon with rapeseed meal as a precursor and its electrochemical properties

In this paper, rapeseed meal is selected as the biomass raw material, KOH is used as the active agent, and N–P co-doped biomass carbon-based materials are prepared by co-activation synthesis of dopant and activator. The obtained N–P co-doped biomass carbon-based material (RM@NP) exhibits a large surface area of 3765.7 m2 g with a hierarchical structure of meso- and micropores. RM@NP is effectively doped with nitrogen and phosphorus elements, resulting in relative mass fractions of nitrogen and phosphorus of 2.32 % and 0.17 %, respectively. To assess their potential as electrode materials for supercapacitors, the electrochemical performance of the carbon materials is investigated. In a three-electrode system, the specific capacitance of the RM@NP reaches 460.0 F g−1 at 1 A g−1 in 6 M KOH, and also the specific capacitance is 344.3 F g−1 at 10 A g−1, with the corresponding retention rate of the capacitance is calculated of 75.0 %. When the specific energy is 10.1 W h kg−1, the RM@NP specific power reaches 625.0 W kg−1 in a two-electrode system. After 10,000 cycles, a retention rate of the capacitance of 83.9 % is achieved.