Background Zinc-ion hybrid capacitors (ZIHCs) are promising energy storage devices due to their high capacitance, energy density, and long cycle life. Achieving optimal performance in ZIHCs requires pairing the Zn anode, which offers high theoretical capacity, with a carbon-based cathode that complements the Zn electrode's characteristics. For applications demanding higher energy density—similar to lithium-ion batteries—while preserving the high power output and long cycle life of supercapacitors, lithium-ion hybrid capacitors (LICs) have been developed. Methods In this study, we synthesized 3D S,O co-doped graphene flakes with a hierarchically porous structure via a reaction between gallate and sulfate anions inside a copper layered hydroxide as a nanoreactor. This doped carbon material was employed as active cathode material in both ZIHCs and LICs. Significant Findings The commercial-like ZIHC device demonstrated a high capacitance of 72 F/g at 0.1 A/g and retained over 93% of its initial capacity after 2000 charge-discharge cycles at 2 A/g. Additionally, the LIC device showed excellent electrochemical performance, with a high operating voltage of 4 V, a capacitance of 28 F/g, and an energy density of 35 Wh/kg at 0.5 A/g. These results provide valuable insights into the design of cathode materials for high-performance ZIHCs and LICs.
