摘要：Supercapacitor technology is an extremely timely area of research with fierce international competition to develop cost-effective, environmentally friendlier EC electrode materials that have real world application. Herein, nitrogen-doped carbons with large specific surface area, optimized micropore structure and surface chemistry have been prepared by means of an environmentally sound hydrothermal carbonization process using defatted soybean ( i.e ., Soybean meal ), a widely available and cost-effective protein-rich biomass, as precursor followed by a chemical activation step. When tested as supercapacitor electrodes in aqueous electrolytes ( i.e. H2SO4 and Li2SO4), they demonstrate excellent capacitive performance and robustness, with high values of specific capacitance in both gravimetric (250–260 and 176 F g−1 in H2SO4 and Li2SO4 respectively) and volumetric (150–210 and 102 F cm−3 in H2SO4 and Li2SO4 respectively) units, and remarkable rate capability (>60% capacitance retention at 20 A g−1 in both media). Interestingly, when Li2SO4 is used, the voltage window is extended up to 1.7 V (in contrast to 1.1 V in H2SO4). Thus, the amount of energy stored is increased by 50% compared to H2SO4 electrolyte, enabling this environmentally sound Li2SO4-based supercapacitor to deliver ~12 Wh kg−1 at a high power density of ~2 kW kg−1.
