Mild chemical-activated hydrothermal porous carbon derived from durian peel biomass for an electrochemical supercapacitor†

Because waste biomass is the ideal precursor for the preparation of porous carbon, the reuse of waste biomass resources has become a current research hotspot. However, because of the complexity of waste biomass and its microstructure, the quality reproduction of discarded biomass is poor. Therefore, it is of great significance to develop a reliable method for the preparation of porous carbon. In this paper, a hydrothermal carbonization treatment could complete the sphere/nanosheet morphology structure adjustment and KHCO₃ could activate the hydrothermal porous carbon while maintaining the spherical morphology. The activated hydrothermal porous carbon with a carbon sphere/nanosheet structure facilitated ion/electrolyte diffusion and increased accessibility between the surface area and electrolyte ions. The durian peel-derived activated hydrothermal porous carbon had a high specific surface area (2100.5 m² g⁻¹), good specific capacitance (267 F g⁻¹ at 1 A g⁻¹) and good cycling stability, with a capacitance loss of only 6.7% after 10 000 charge–discharge cycles. A Na₂SO₄-based cell achieved a maximum energy density of 14.45 W h kg⁻¹ at 225 W kg⁻¹; even at a higher power density of 4500 W kg⁻¹, the specific energy remained at 10.75 W h kg⁻¹.