Soybean meal-derived heteroatoms-doped porous carbons for supercapacitor electrodes

The precursor (soybean meal) was directly pyrolyzed to fabricate N, O co-doped hierarchical porous carbons (HPCs) through NaCl/KCl/KHCO3 molten salt method. The obtained HPCs possess a well-developed 3D hierarchical porous structure with a maximum specific surface area of 1945 m2 g−1. Such a phenomenon is conducive to ion storage and transmission. In addition, abundant heteroatoms had been successfully incorporated into the HPCs, endowing additional pseudocapacitance to the carbon materials. Hence, HPC-3 could achieve a maximum specific capacitance of 507 F g−1 in 1 M H2SO4 electrolyte when the current density was 0.2 A g−1. Moreover, the supercapacitor cell assembled from two identical HPC-3 electrodes can achieve a reasonably high energy density of 12.4 Wh kg−1 at a power density of 50 W kg−1. Consequently, KHCO3 is a good pore-forming agent, and the obtained high-performance electrode material has broad prospects for supercapacitor application. [Display omitted] •Activating soybean meal in air using molten salt method produces porous carbon.•KHCO3 can serve as a good pore-forming agent.•HPC consists of N, O heteroatoms and has large surface area and pore volume.•HPC-3 achieves a maximum specific capacitance of 507 F g−1 in 1 M H2SO4.•The symmetric supercapacitor shows high energy density of 12.4 Wh.kg−1.