Polyacrylonitrile Derived Porous Carbon for Zinc‐Ion Hybrid Capacitors with High Energy Density

Aqueous zinc‐ion hybrid capacitors (ZIHCs) attract widespread attention due to their excellent electrochemical performance, safety, and low cost. Here, a honeycomb‐like porous carbon is synthesized as the cathode of ZIHCs via facile pre‐oxidation in combination with an activation process. The pre‐oxidized porous carbon (PPC) displays a larger specific surface area and faster electrochemical kinetics compared to porous carbon without pre‐oxidation (PC), realizing a superior electrochemical performance. The PPC cathode can deliver a capacity of 238 mAh g −1 at 0.1 A g −1 . Besides, the hybrid capacitors can achieve a high energy density of 193.6 Wh kg −1 at 76.6 W kg −1 and 109.5 Wh kg −1 at a maximum power density of 3981 W kg −1 . More importantly, the hybrid capacitor exhibits a good cycling stability with a capacity retention of 83 % after 20000 cycles at a high current density of 2 A g −1 . This cathode material – with an excellent electrochemical performance – could pave the way for application of ZIHCs.