Unveiling the X-Ray Absorption Chemistry of H3.78V6O13 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 H3.78V6O13 microspheres with a stable internal framework and intrinsic metallic properties as a high-performance cathode for ZIBs are proposed and utilized. The reversible Zn(2+)insertion/de-insertion mechanism in H(3.78)V(6)O(13)through 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 H3.78V6O13. The as-prepared H3.78V6O13 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.