A Novel Composite Polymer Electrolyte with Active SBA-15 Filler for Chloride Ion Batteries

The development of chloride ion batteries (CIBs) presents a promising alternative to lithium-ion batteries due to the abundance of chloride resources and improved safety. However, the dissolution of cathode materials in liquid electrolytes significantly limits their practical application. In this study, a new type of composite polymer electrolyte (CPE) is designed by incorporating ethylene carbonate (EC)-confined mesoporous silica (designated as active SBA-15) into a poly(ethylene oxide) (PEO) and tributylmethylammonium chloride (TBMACl) matrix. The active filler not only suppresses the crystallinity of the polymer matrix but also offers extra ion-conductive pathways. The resulting CPE exhibits an enhanced room-temperature ionic conductivity of 2.45 × 10^–5 S cm^–1, a broad electrochemical stability window up to 5.3 V, and excellent mechanical strength. Electrochemical tests of FeOCl/Li half-cells using this electrolyte deliver an initial discharge capacity of 161 mAh g^–1 and retain a capacity of 60 mAh g^–1 after 20 cycles. These results demonstrate the effectiveness of active SBA-15 in enhancing the electrochemical and mechanical properties of polymer electrolytes, offering a feasible pathway for next-generation all-solid-state CIBs with enhanced performance.