Flexible and Dynamic Interfacial Desolvation in High‐Entropy Electrolyte for Dendrite‐Free Aqueous Zinc‐Ion Batteries

Abstract

Abstract Aqueous zinc‐ion batteries are promising candidates beyond lithium‐ion technologies, but the intrinsic hydrogen‐down orientation of interfacial water under negative bias, together with ion depletion at the electrode surface, promotes inhomogeneous Zn plating and substantial hydrogen evolution. Here, a high‐entropy flexible electrolyte (HEFE) is demonstrated that leverages the fast water‐exchange kinetics of Li⁺, K⁺, and Cs⁺. By deliberately inducing cation‐hydration disequilibrium, the HEFE forms flexible Zn(H 2 O) m 2+ ( m ≤ 6) solvation structures embedded in a disordered water network, enhancing ionic conductivity and alleviating ion‐transport limitations. Under cathodic bias, a progressive desolvation from Zn(H 2 O) 6 2+ to Zn(H 2 O) x 2+ ( x ≤ 5) proceeds while retaining aqueous disorder, thereby suppressing hydrogen evolution and enabling 3500 h of deep cycling at 1 mA cm −2 /3 mAh cm −2 . For iodine cathodes, the HEFE induces a pathway shift from the conventional I − →I 2 route to a solid–solid (CsI→I 2 ) conversion, fundamentally inhibiting iodide shuttling and extending full‐cell life to 3600 cycles at 1 A g −1 . Beyond Zn, the solvation‐heterogeneity strategy opens avenues for reversible multivalent electrochemistry and advancing next‐generation energy‐storage systems.