Anion‐Anchored Polymer‐in‐Salt Solid Electrolyte for High‐Performance Zinc Batteries

Solid polymer electrolytes hold promise for addressing key challenges in rechargeable zinc batteries (ZBs) utilizing aqueous electrolytes. However, achieving simultaneous high ionic conductivity, excellent mechanical strength, and a high cation transference number while effectively suppressing Zn dendrites remains challenging. Herein, we design a novel polymer-in-salt solid electrolyte (PISSE) composed of polyacrylonitrile (PAN), zinc chloride (ZnCl₂), and niobium pentoxide with oxygen vacancies (Nb₂O_5-x) with high ionic conductivity. PAN polymer matrix provides the electrolyte good mechanical properties and solubility of Zn salt. The high concentration of ZnCl₂ effectively decouples the Zn²⁺ from polymer chain segments and provides more ionic conduction amorphous region. Moreover, incorporating Nb₂O_5-x filler accelerates Zn²⁺ desolvation by anchoring (Zn_xCl_y)^2x-y clusters and enhances the system's mechanical properties, achieving a superior Zn²⁺ transference number (~0.93) and interfacial stability. Consequently, the optimized PISSE demonstrates exceptional stability during prolonged cycling periods, wide temperature range operation (-40 °C to 60 °C), remarkable flexibility, and compatibility with diverse electrode materials. This study provides valuable insights into the design of solid-state electrolytes based on ZBs and elucidates their multifunctional prospects.