A novel PMA/PEG-based composite polymer electrolyte for all-solid-state sodium ion batteries

In recent years, development of all-solid-state batteries has become a promising approach to improve the safety of batteries. Herein, we report the preparation of a new composite polymer electrolyte (CPE) for use in all-solid-state sodium ion batteries. The CPE comprising of poly(methacrylate) (PMA), poly(ethylene glycol) (PEG), α-Al₂O₃ with acidic surface sites, and NaClO₄ exhibited high ionic conductivity (1.46 × 10^-4 S·cm^-1 at 70 ℃), wide electrochemical stability window (4.5 V vs. Na⁺/Na), and good mechanical strength. With the introduction of the prepared CPE and Na₃V₂(PO₄)₃, the final all-solid-state sodium ion batteries showed good rate and cycle performance, with a high reversible capacity of 85 mAh·g^-1 when operated at 0.5 C (1 C = 118 mA·g^–1) and 94.1% capacity retention rate after 350 cycles at 70 ℃. Our work provides a novel solid electrolyte for the development of all-solid-state sodium ion batteries.