Rational Design of Ni-Doped V₂O₅@3D Ni Core/Shell Composites for High-Voltage and High-Rate Aqueous Zinc-Ion...

Aqueous zinc-ion batteries (ZIBs) have significant potential for large energy storage systems because of their high energy density, cost-effectiveness and environmental friendliness. However, the limited voltage window, poor reaction kinetics and structural instability of cathode materials are current bottlenecks which contain the further development of ZIBs. In this work, we rationally design a Ni-doped V₂O₅@3D Ni core/shell composite on a carbon cloth electrode (Ni-V₂O₅@3D Ni@CC) by growing Ni-V₂O₅ on free-standing 3D Ni metal nanonets for high-voltage and high-capacity ZIBs. Impressively, embedded Ni doping increases the interlayer spacing of V₂O₅, extending the working voltage and improving the zinc-ion (Zn₃₀²⁺) reaction kinetics of the cathode materials; at the same time, the 3D structure, with its high specific surface area and superior electronic conductivity, aids in fast Zn₃₀²⁺ transport. Consequently, the as-designed Ni-V₂O₅@3D Ni@CC cathodes can operate within a wide voltage window from 0.3 to 1.8 V vs. Zn₃₀/Zn₃₀²⁺ and deliver a high capacity of 270 mAh g^-1 (~1050 mAh cm^-3) at a high current density of 0.8 A g^-1. In addition, reversible Zn²⁺ (de)incorporation reaction mechanisms in the Ni-V₂O₅@3D Ni@CC cathodes are investigated through multiple characterization methods (SEM, TEM, XRD, XPS, etc.). As a result, we achieved significant progress toward practical applications of ZIBs.