Dual Regulation of Bulk Heterostructure and Engineered Cathode‐Electrolyte Interphase in Vanadium Cathodes for Durable Zinc Storage

Abstract Vanadium‐based cathodes for aqueous zinc‐ion batteries (AZIBs) face critical challenges in practical capacity and low‐current‐density cycling stability. Herein, a synergistic strategy is introduced that overcomes these limitations through the co‐engineering of an activatable bulk precursor and a dynamic in situ‐formed interface. A porous, V ³⁺ ‐rich 0.3CaV ₂ O ₄ ‐0.7V ₂ O ₃ heterostructure (CaVO‐4) specifically designed to undergo a profound in situ electrochemical activation into highly active phases is first constructed. Concurrently, by leveraging supplemental SO ₄ ²⁻ in the electrolyte, a stable CaSO ₄ ·2H ₂ O cathode‐electrolyte interphase (CEI) layer is formed in situ via reaction with Ca ²⁺ released during cycling. By serving a dual role, the CEI ensures structural durability and simultaneously enables the intrinsic kinetics of the bulk. This “bulk‐to‐interface” synergy manifests in electrochemical performance, including 89.3% capacity retention over 300 cycles at 0.5 A g ⁻¹ , an extraordinary rate capability of 424.4 mAh g ⁻¹ at 20 A g ⁻¹ , and a high specific capacity of 479.2 mAh g ⁻¹ at 0.2 A g ⁻¹ . Advanced characterizations, including in situ XRD and ex situ XPS/XAFS, combined with DFT calculations, unravel the synergistic mechanisms underpinning the enhanced Zn ²⁺ storage. This work pioneers a paradigm that unites rational bulk activation with interfacial self‐optimization, providing a strategy for durable, high‐performance cathodes in advanced energy storage.