K⁺ pre-intercalation tailored interlayer hydration engineering in hydrated V₂O₅: A high-capacity and ultrastable...

Hydrated V₂O₅ is a promising cathode material for aqueous zinc-ion batteries (ZIBs), where interlayer structural H₂O plays a crucial role in tuning Zn²⁺ storage performance. Nevertheless, the precise modulation of interlayer H₂O content remains a major challenge in material synthesis. Herein, we employ pre-intercalated K⁺ ions as structural mediators to modulate the interlayer H₂O content in hydrated V₂O₅, successfully synthesizing K_0.4V₂O₅·0.24H₂O (KVOH) with an optimized hydrated structure. The engineered hydration structure creates a greatly favorable interlayer electrostatic shielding microenvironment that effectively weakens the attraction between intercalated Zn²⁺ and VO framework, thereby facilitating highly reversible and rapid Zn²⁺ (de)intercalation. Simultaneously, the pre-intercalated K⁺ ions and interlayer H₂O molecules act as structural pillars that cooperatively stabilize the host framework during prolonged charge/discharge cycling. Benefiting from these advantages, KVOH delivers a high zinc storage capacity of 469.6 mAh g^-1 at 0.5 A g^-1 and maintains 88.2% of its initial capacity after 500 cycles. Moreover, it also demonstrates outstanding long-term cycling stability, achieving 79.0% capacity retention after 5000 cycles at 10 A g^-1. This work reveals the crucial role of interlayer hydration chemistry in governing Zn²⁺ storage performance and provides a novel strategy for precisely modulating interlayer water content in hydrated V₂O₅ cathodes.