Construction of high energy density and long cycle life zinc-ion hybrid capacitors based on Wedelia chinensis-derived biomass porous carbon

Zinc ion hybrid capacitors (ZIHCs) have received much attention due to their low cost, safety, and green features. However, its development is seriously restricted by defects such as low energy density and insufficient cycle life. The selection of suitable capacitive materials can effectively enhance their electrochemical performance. Porous carbon materials become the choice of capacitive materials for ZIHCs due to their high ion adsorption capacity and fast kinetic behavior. In this paper, an oxygen-enriched biomass-derived nanoporous carbon was prepared by pyrolysis of Wedelia chinensis combining the chemical activation. The oxygen-rich functional groups on the surface of this nanoporous carbon can provide additional pseudocapacitance and improve the wettability of the material. The excellent electrochemical performance of the material in aqueous electrolyte was verified by assembling symmetrical capacitor (SCs) and ZIHC devices. Specifically, as high as 151 W h kg(-1) of energy density and 18 kW kg(-1) of power output as well as 25,000 cycles of long cycle life with 97.4% of capacity retention were demonstrated by as-assembled ZIHC.