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

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(H₂O)_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(H₂O)₆ ²⁺ to Zn(H₂O)_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^-→I₂ route to a solid-solid (CsI→I₂) 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.