In situ polymerized ether-based polymer electrolytes towards practical lithium metal batteries

Commercial lithium–ion batteries that use flammable liquid electrolytes face significant safety risks, such as fires caused by electrolyte leaks. Solid polymer electrolytes (SPEs) present a viable solution to this problem, with ether-based polymer electrolytes standing out due to their superior stability and compatibility with lithium metal. The in situ ring-opening polymerization of cyclic ether monomers not only simplifies the battery manufacturing process but also improves the solid/solid interfacial contacts between electrolytes and electrodes, thereby significantly reducing interfacial impedance. In this paper, we review the mechanisms of ring-opening polymerization for cyclic ether monomers and analyze the ionic conduction of ether-based polymer electrolytes. We also explore the in situ curing mechanisms for several representative cyclic ether monomers and assess research advancements in this area. Additionally, this paper discusses the sustainability of ether-based polymer electrolytes and provides an outlook on future research and sustainability initiatives in the field.