Microwave‐Assisted Synthesis of Heteroatom‐Doped Activated Carbon/ <scp> MnO ₂ </scp> Composite Electrode for Zinc‐Ion Energy Storage Devices

ABSTRACT The N, S co‐doped meso‐microporous activated carbon (NSMAC) from Samanea saman biomass is synthesized using a combined hydrothermal and microwave carbonization process. The microwave heating technique is further used to synthesize its composite with MnO 2 for the development of cathode materials for prototype zinc‐ion hybrid supercapacitors (ZIHS) and zinc‐ion batteries (ZIB). The fabricated ZIHS with the composite cathode demonstrates an energy density of approximately 95.4 Wh kg −1 and a power density of 0.16 kW kg −1 based on the total mass of the active materials coated on both the cathode and anode. When used as the cathode in a ZIB, the composite demonstrates a specific capacity of 324.6 mAh g −1 (at 0.1 A g −1 ), a high energy density of 443.2 Wh kg −1 , and a high power density of 6.2 kW kg −1 based on the mass of the active material coated on the cathode. Additionally, the ZIB maintains a capacity retention of 75.2% over 2000 cycles at a high current density of 5 A g −1 . Thus, microwave synthesis of NSMAC/MnO 2 composite presents a promising approach for development of high performance electrodes for ZIHS and ZIB.