摘要
Aqueous zinc-ion batteries (AZIBs) offer strong potential for grid-scale energy storage, yet their performance is often constrained by sluggish Zn2+ diffusion and insufficiently stable cathode hosts. In this work, we develop a Mo-doped hydrated vanadium oxide (MoVOH/VOH) cathode designed to overcome these limitations. Using operando X-ray diffraction, operando XANES, and extended X-ray absorption fine structure (EXAFS) analysis combined with density functional theory (DFT) calculations, we not only elucidate the Zn2+ storage mechanism but also resolve the previously controversial structural position of Mo within the VOH framework. Our results demonstrate that high-oxidation-state Mo ions are predominantly incorporated substitutionally within the VO layers, rather than occupying interlayer sites. This substitution significantly improves electronic conductivity, accelerates Zn2+ transport, and stabilizes the VOH lattice during repeated cycling. Consequently, the MoVOH/VOH cathode delivers a high capacity of 405 mAh g−1 at 0.1 A g−1, excellent rate capability, and 82% capacity retention after 300 cycles at 5 A g−1, and an energy density of ∼284 Wh kg−1 at 71 W kg−1. These findings demonstrate that Mo doping is an effective strategy for tailoring vanadium-based hosts for high-performance AZIBs and provide direct experimental and theoretical insight into the local structural role of Mo, addressing a key unresolved issue in hydrated vanadium oxides.
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•Mo-doped hydrated vanadium oxide (MoVOH/VOH) is developed as a high-performance cathode for aqueous zinc-ion batteries.•Synchrotron EXAFS and DFT reveal that Mo6+ substitutes V within the VO layers rather than occupying interlayer sites.•Operando synchrotron XRD, XANES, and DFT calculations reveal Mo substitution enhances electronic conductivity, Zn2+ transport, and lattice stability.•Reversible multivalent redox of both V (V5+/V3+) and Mo (Mo6+/Mo4.5+) contributes to the high charge-storage capability.•The MoVOH/VOH delivers 405 mAh g−1 at 0.1 A g−1 with 82% retention over 300 cycles at 5 A g−1 and energy density of ∼284 Wh kg−1.