Activated carbon derived from hydrochar of food waste for supercapacitor: Effect of components on electrochemical performance

Herein, rice, cabbage, and pork were chosen as typical starch, lignocellulose, and protein food wastes, respectively. Hydrothermal carbonization and KOH activation were used to prepared activated carbon from single and mixed food wastes, with a focus on the effect of components on the electrochemical performance of activation carbon as EDLC electrode materials. The results showed that the mesoporous and carbonyl group in activated carbon were mainly contributed by the starch in feedstocks, while the micropores, pyrrolic-N, and edge defects in activated carbon were determined by the lignocellulose and protein in feedstocks. Compared with single components, the mixed food wastes were more suitable to produce activated carbon with high specific capacitance. Among them, the three-component mixture presented the highest specific capacitance of 327 F/g at 0.5 A/g. However, the activated carbon from the rice owed high capacitance retention rate of 83.7%. In general, the copresence of lignocellulose and protein in food wastes were conducive to the enhancement of specific capacitance for activated carbon. The starch rich food waste was feasible to produce activated carbon with well capacitance retention rate. The results could give a guide to select suitable food wastes that could produce high efficiency electrode materials.