Heterointerface-Regulated Deep Charging in Vanadium Oxides for Aqueous Zinc-Ion Batteries With Wide Voltage Window

Vanadium-based cathodes in aqueous zinc-ion batteries are generally considered unstable at wide voltage windows due to structural dissolution and interfacial side reactions, which limit reversibility under deep-charging conditions. To address whether deep charging leads to irreversible structural changes, we construct a core-shell vanadium-based oxide material (FeVO) using a one-step hydrothermal strategy, enabling stable operation over a 0.2-1.8 V voltage window. The FeVO cathode delivers a high capacity of ∼500 mAh g^-1 at 0.1 A g^-1 and retains 66% of its capacity after 1200 cycles at 5 A g^-1 within a wide voltage window of 0.2-1.8 V. Structural and electrochemical analyses show that deep charging activates a cooperative response within the Fe-V-O framework, while the energy-storage mechanism remains governed by reversible Zn²⁺/H⁺ co-insertion. Fe incorporation stabilizes the wide-voltage-window reaction pathway, suppresses side reactions, and promotes Zn²⁺ diffusion, redefining the intrinsic reaction nature of vanadium-based cathodes under deep-charging conditions and provides a mechanistic framework for designing deep charging-discharging aqueous zinc-ion battery cathodes.