Resolving the Controversy of Zinc Pyrovanadate in Aqueous Zinc‐Ion Batteries: Intrinsic Inertness, Formation Mechanism, and Characterization Pitfalls

Abstract Zinc pyrovanadate (Zn 3 (OH) 2 V 2 O 7 ∙2H 2 O, denoted as ZVO) has been a subject of considerable debate in aqueous zinc‐ion batteries (AZIBs) research, with conflicting reports regarding its electrochemical activity. This study resolves these controversies by demonstrating ZVO's inherent electrochemical inertness through a combination of experimental and theoretical approaches. It is revealed that the previously reported “active ZVO” originates from hydrated vanadium oxide (HVO) phase impurities. Furthermore, a dynamic pH‐dependent mechanism governing ZVO formation during long‐term cycling is elucidated, influenced by both the vanadium cathode and the zinc anode. Crucially, two often‐overlooked experimental artifacts — residual cathode water and delayed battery disassembly — that can lead to the erroneous detection of ZVO during ex situ characterization are identified. This work clarifies the role of ZVO in AZIBs, providing valuable insights for the rational design of high‐performance and stable aqueous energy storage systems.