Modulating Adsorption Intermediate Metastability for Tip-Directed Zinc Stripping and Suppressed Vanadium Dissolution Toward Long-Cycling Zinc-Vanadium Batteries.

Abstract

The metastable adsorbed intermediates formed during the lattice detachment of Zn atoms and V^{n +} ions govern the reaction kinetics and interfacial morphology evolution during dissolution. Resultant inhomogeneous Zn stripping and progressive V dissolution synergistically promote dead Zn formation and cathode material degradation, substantially impeding the commercialization of Zn-V batteries. Here, to facilitate Zn tip-stripping electrochemistry and suppressed vanadium dissolution, a robust adhesion ionic liquid ([BVIM]Br) modified PAM gel electrolyte (PAM-IL) was strategically designed. Leveraging steric hindrance of polymer segments and the directional coordination of anions and cations, the PAM-IL electrolyte delocalizes charge accumulation and suppresses overstabilization of tip-localized complexes, thereby reversing the adsorption asymmetry behavior (ΔG_ads-tip > ΔG_ads-root) to achieve tip-targeted zinc stripping. Concurrently, strong ion-dipole interactions within PAM-IL elevate the activation barrier for V dissolution and combine with its butyl-functionalized hydrophobic moieties to impede water molecule penetration and suppress vanadium dissolution. Therefore, the as-prepared Zn||PAM-IL||NH₄V₄O₁₀ batteries deliver a reversible capacity of 266.4 mAh g^-1 at 1 A g^-1 after 2000 cycles and retained a higher capacity retention (82.3%) after 250 cycles than aqueous electrolyte (28.1%) with extreme-low current density of 0.2 A g^-1. Furthermore, the PAM-IL exhibits exceptional cycling stability over a wide temperature range, from 0 °C to 60 °C.