Rapeseed meal-derived N,S self-codoped porous carbon materials for supercapacitors

The conversion of bio-waste rich in heteroatoms into useful porous carbons with good chemical properties is a feasible approach contributing to electrode materials for supercapacitors. In this work, rapeseed meal rich in crude protein is used as the precursor to synthesize N,S self-codoped porous carbons. The carbon sample obtained via pre-carbonization followed by KOH activation (RM@HTC) exhibits a developed micro-mesoporous interconnected carbon structure with a large specific surface area of up to 3283.2 m(-2) g(-1). The N and S atoms are well retained with a N content of 1.49% for RM@HTC. In a three-electrode system, the RM@HTC-based electrode reaches a high specific capacitance of 303.4 F g(-1) at a current density of 1 A g(-1), and the specific capacitance is retained at 210.0 F g(-1) at 10 A g(-1). In a two-electrode system, the energy density reaches 9.0 W h kg(-1) at a power density of 625.0 W kg(-1). RM@HTC also exhibits excellent cycle stability with a capacity retention rate of 92.9% after 10 000 charge-discharge cycles at 10 A g(-1).