Strategies for flame-retardant polymer electrolytes for safe lithium-based batteries

The advancement of lithium-based batteries has spurred anticipation for enhanced energy density, extended cycle life and reduced capacity degradation. However, these benefits are accompanied by potential risks, such as thermal runaway and explosions due to higher energy density. Currently, liquid organic electrolytes are the predominant choice for lithium batteries, despite their limitations in terms of mechanical strength and vulnerability to leakage. The development of polymer electrolytes, with their high Young's modulus and enhanced safety features, offers a potential solution to the drawbacks of traditional liquid electrolytes. Despite these advantages, polymer electrolytes are still susceptible to burning and decomposition. To address this issue, researchers have conducted extensive studies to improve their flame-retardant properties from various perspectives. This review provides a concise overview of the thermal runaway mechanisms, flame-retardant mechanisms and electrochemical performance of polymer electrolytes. It also outlines the advancements in flame-retardant polymer electrolytes through the incorporation of various additives and the selection of inherently flame-retardant matrix. This review aims to offer a comprehensive understanding of flame-retardant polymer electrolytes and serve as a guide for future research in this field.