O-doped porous carbon derived from biomass waste for high-performance zinc-ion hybrid supercapacitors

As one of the next-generation electric energy storage devices, zinc-ion hybrid supercapacitors (ZHS) gain increasing attention due to their advantages inherited from batteries and capacitors. In this paper, we propose a KOH activation method to prepare porous carbon derived from oxygen-rich orange peel for high-performance ZHS. O-doped hierarchical porous carbon with large specific surface area (2156 m2/g) was obtained and further employed as cathode materials by simply adjusting KOH dosage and activation temperature. The AC850 delivers a high specific capacity of 125.7 mAh/g at 1 A/g and a capacity retention rate of 81.3% at a high current density of 10 A/g in 1 M ZnSO4. Additionally, the porous carbon based on the ZHS can deliver a remarkable 69.4 Wh/kg at 7570 W/kg, as well as outstanding cycle stability (≈92% capacity retention rate after 3000 cycles at 10 A/g).