Porous carbon prepared via combustion and acid treatment as flexible zinc-ion capacitor electrode material

To meet the requirements for high energy/power density, safety and flexibility of wearable electronic devices simultaneously, a solid-state zinc-ion capacitor (ZIC) is assembled by integrating zinc nanosheets anode and porous carbon cathode with gelatin gel as electrolyte. Herein, the oxygen-enriched three-dimensional porous carbon has been synthesized as cathode of ZIC via a facile combustion and sequential acid-treatment process. Taking advantages of the rich oxygen-containing functional groups to provide pseudocapacitance and the specific pore structure of porous carbon to endow fast electrochemical kinetics of cathode, the assembled ZIC could deliver the superb specific capacity of 132.7 mA h g−1, excellent energy density of 82.36 W h kg−1 and superior cycling stability with 87.6% capacity retention over 10,000 cycles at a current density of 1.0 A g−1. Impressively, the assembled solid-state ZIC based on OPC is flexible enough to withstand various deformations including bending and twisting at large angles, which are promising to be applied in portable electronics.