Cr3+ pre-intercalated hydrated vanadium oxide as an excellent performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are regarded as the next promising large scale energy storage systems owing to their low cost, high safety and environmental friendliness. Vanadium-based materials are one of the most important cathodes of ZIBs due to their high abundance and multielectron transfer of various oxidations of vanadium. Nevertheless, the strong electrostatic interaction between Zn2+ and cathodes, intrinsic poor electronic conductivity and solubility of vanadium-based cathodes in electrolytes bring about inferior electrochemical performance. In this work, we introduce aliovalent Cr3+ into the interlayer of hydrated vanadium oxide (Cr-VOH) as pillar to significantly increase the structural stability and electrochemical reversibility. The pre-intercalation of Cr3+ also provides an enhanced electronic conductivity and fast Zn2+ diffusion dynamics, enabling superior Zn2+ storage performance of the Cr-VOH cathode. As a result, the Cr-VOH cathode exhibits a high reversible discharge capacity of ~380 mAh g−1 at 50 mA g−1, excellent rate capacity of 166 mAh g−1 at 8 A g−1 and prolonged cycling stability over 500 cycles. Furthermore, it displays a high energy density of 273.6 W h kg−1 at 0.05 A g−1 and the power density of 4960 W kg−1 at 8 A g−1, contributing to the practical application potential of aqueous ZIBs.