A novel modified PI Separator with enhanced Dendrite-Suppressed and Puncture Prevention and Better size stability for Room Temperature Sodium-Sulfur Batteries

Commercial battery separators (Celgard) have poor wettability, poor heat resistance, and low needle punching strength, and the growth of sodium dendrites can easily pierce the separators, seriously threatening the life and safety of room-temperature sodium-sulfur batteries (RT Na-S). In this work, Polyimide copolymerized with polyether (PI-PEO) membrane was prepared by an electrospinning method. By introducing polyether segments into the polyimide molecular chain and constructing a nanofiber structure, the polarity and fiber structure of the material improved the wettability of the electrolyte, and the toughness of the membrane was improved while ensuring the size stability of the membrane and further resisted the puncture of sodium dendrites. As a result, the battery assembled with the PI-PEO separator exhibits excellent cycle stability. The capacity remains 450 mAh g−1 after 2000 cycles at 3 A g-1. At the same time, the PI-PEO shows a higher ionic conductivity (1.48 mS cm-1), better size stability and electrolyte wettability than Celgard. This work provides a novel and effective method for developing durable room temperature sodium-sulfur batteries.