An Aqueous Zn‐Ion Hybrid Supercapacitor with High Energy Density and Ultrastability up to 80 000 Cycles

Abstract Integrating a battery‐type electrode to build a hybrid supercapacitor is a promising approach to improve the overall energy density of a supercapacitor‐type energy storage device without sacrificing its power output. However, this strategy is usually achieved at the expense of cycling lifespan. In this work, a hybrid supercapacitor comprising Zn foil and porous carbon derived from chemical activated graphene (aMEGO) is developed, and the trade‐off between energy density and cycling life is well‐balanced by the utilization of 3 m Zn(CF 3 SO 3 ) 2 electrolyte with high Zn stripping/plating efficiency. Such a hybrid supercapacitor demonstrates an energy density of 106.3 Wh kg −1 and a power density of 31.4 kW kg −1 , and significantly a wide operation voltage of 1.9 V is achieved in aqueous electrolyte. Benefitting from the high Zn stripping/plating efficiency, the Zn‐aMEGO hybrid‐supercapacitor also exhibits an ultralong cycling life up to 80 000 cycles with capacity retention of 93%, which is comparable to that of conventional electrochemical double‐layer capacitors.