High-performance activated carbon cathodes from green cokes for Zn-ion hybrid supercapacitors

Activated carbons (ACs) were successfully obtained through direct KOH activation method using pitch coke (PHC) and petroleum coke (PMC) as precursors. The electrochemical properties of Zn-ion hybrid supercapacitors (ZICs) assembled with the prepared ACs as electrodes were further investigated. The results showed that the PHC derived AC displayed suitable oxygen functional groups, sufficient specific surface area and favorable porosity, displaying excellent electrochemical performances with an outstanding specific capacitance of 146.4 mAh/g at 0.1 A/g, a satisfactory rate performance of 58% (from 0.1 to 10 A/g) and a high cycling stability of 95% after 5000 cycles. Furthermore, the as-obtained AC-PHC-based ZICs also delivered prominent energy output of 117 Wh/kg at 160 W/kg and 68 Wh/kg at 15.8 kW/kg.