Valence Engineering via Polyoxometalate‐Induced on Vanadium Centers for Efficient Aqueous Zinc‐Ion Batteries

Layered vanadium‐based compounds have attracted attention as cathode materials for aqueous zinc‐ion batteries (AZIBs) because of their low cost, high theoretical specific capacity, and abundant vanadium valence states. However, the slow migration of Zn2+ ions and their poor cycling stability hinder their practical application in AZIBs. Herein, using a one pot solvothermal method, the polyoxometalates (POMs) were inserted into the aluminum vanadate interlayer spacing, and a series of novel three‐dimensional nanoflower cathode materials (HAVO‐MMo6‐X) were successfully fabricated. The unique electron‐rich structure of the POMs accelerated the migration of Zn2+ on the cathode to obtain a high specific capacity. Owing to the synergistic pillar effect of POMs and HAVO, the interlayer spacing of HAVO‐FeMo6‐50 increased to approximately 14.33 Å. X‐ray absorption fine structure spectroscopy was used to analyze the coordination environments of the cathode materials. A combination of in situ and ex situ characterization techniques demonstrated the storage mechanism of Zn2+ during the charge/discharge process. Furthermore, the experimental results and DFT calculations indicated that the introduction of POMs had the dual function of improving conductivity and reducing the Zn2+ migration barrier. Thus, this work provides a new perspective on the synergistic interaction between POMs and metal compounds.