Unveiling the X-Ray Absorption Chemistry of H_3.78V₆O₁₃ Cathode for Aqueous Zinc-Ion Batteries

The low cost and intrinsic safety of rechargeable aqueous zinc-ion batteries (ZIBs) contribute to their significant potential in grid-level energy storage systems. However, the limited cathode options still hinder the development of ZIBs, which always delivers poor rate capacities and cycling stability. Herein, Monoclinic phase H_3.78V₆O₁₃ microspheres with a stable internal framework and intrinsic metallic properties as a high-performance cathode for ZIBs are proposed and utilized. The reversible Zn²⁺insertion/de-insertion mechanism in H_3.78V₆O₁₃through ex situ X-ray diffraction, X-ray absorption near-edge structure, and in situ Raman involves the enlargement/shrink of interplanar distance, the decrease/increase of the V valance, and the open/recombine of V─O/V─V bonds. Further, experiments and theoretical calculations elucidate the superior electrochemical performance and extraordinary reaction kinetics in H_3.78V₆O₁₃. The as-prepared H_3.78V₆O₁₃ cathode delivers high specific capacity of 406 mAh g^–1 at 0.1 A g^–1, excellent structure stability with 100% manifested after 120 cycles at 0.5 A g^–1, 72.9% retained after 15 000 cycles at 10 A g^–1. This research offers distinctive perspectives on the development of high-performance cathode materials for ZIBs and enhances the understanding of the electrochemical reaction mechanisms of vanadium oxides. © 2023 Wiley-VCH GmbH.