Ion‐Pump‐Regulated Highly Conductive Polymer Electrolyte to Enable the First All‐Solid‐State Rechargeable Fluoride‐Ion Pouch Cells

Abstract Solid polymer electrolytes represent a promising but almost underexplored avenue in all‐solid‐state fluoride‐ion batteries. Hereby, an ion pump engineering approach is proposed to develop F‐ion composite electrolytes that combine the advantages of soft‐interface polymer and Sn‐based inorganic electrolyte. In this system, β‐PbSnF 4 (PSF) is embedded into a polyvinyl alcohol (PVA)‐based anion receptor matrix with CsF as fluoride salt to construct a high‐speed F − conduction network. The Lewis acidic PSF anchored within the PVA chain segments facilitates the dissociation of CsF and provides an additional source of F‐ions. PSF also serves as an ion modulator to weaken the excessive binding of hydroxyl hydrogen to fluoride ions through a “push‐pull” effect, thereby creating a milder F migration environment. The optimized polymer electrolyte achieves a high ionic conductivity of 1.04 × 10 −3 S cm −1 at 60 °C and a F‐ion transference number of 0.53 (five times that of the system without PSF), marking the highest performance level for polymer‐based F‐ion electrolytes to date. Leveraging the low interfacial activation energy of organic–inorganic flexible surface, the first polymer‐based all‐solid‐state fluoride‐ion pouch cell is presented with CuF 2 cathode and Pb foil anode, demonstrating a discharge capacity of 119.05 mAh g −1 (1 mAh) with excellent reversibility under near room temperature and lowered operation pressure.