Flame-Retardant Polymer Electrolyte for Sodium-Ion Batteries

Sodium-ion batteries present an appealing option for large-scale energy storage applications due to their high natural abundance and low production costs. However, the safety issue remains a major obstacle in current development, primarily owing to the use of liquid electrolytes (LEs), which can lead to leakage and combustion. To achieve both high energy density and enhanced safety, researchers are increasingly focusing on solid-state electrolytes (SSEs). Solid-state polymer electrolytes (SPEs) have garnered notable attention due to their superior mechanical flexibility and electrochemical stability. Nonetheless, traditional SPEs can also undergo combustion and decomposition under extreme conditions due to polymer inherent flammability. Therefore, it is imperative to conduct research and design flame-retardant SPEs in order to enhance their reliability and safety in practical applications. This review provides a comprehensive overview of the mechanisms underlying battery thermal runaway and offers guidance for designing batteries with enhanced safety. In addition to reviewing recent advancements in flame-retardant polymer solid-state sodium battery research, it also presents a systematic classification and introduction of studies on high-safety polymer electrolytes. Furthermore, it delves into diverse perspectives and approaches towards addressing the issue of safety in polymer sodium battery, ultimately outlining future research directions for this particular field.