Cu ²⁺ Doping-Induced Microstructural Engineering of V ₂ O ₅ Cathodes for High-Performance Zinc-Ion Hybrid Supercapacitors with Enhanced Energy and Rate Capability

Aqueous zinc-ion hybrid supercapacitors have garnered widespread attention as safe and cost-effective energy storage devices, yet their performance is frequently constrained by cathode materials. In this work, Cu2+-doped V2O5 cathodes with diverse morphologies were fabricated via a facile microstructural engineering strategy to enhance Zn2+ storage capability. Using the optimized V2O5 as the cathode and capacitive activated carbon as the anode, a novel zinc-ion hybrid supercapacitor was assembled. Under the optimal mass ratio of the electrodes, the hybrid supercapacitor delivers a maximum specific capacity of 70.3 mAh g–1 and an energy density of 36.7 Wh kg–1. Furthermore, the precipitation and dissolution of Zn4(OH)6SO4·5H2O are identified as a critical contributor to the capacity. This study provides a feasible approach for the design of high-performance aqueous zinc-ion hybrid supercapacitors.