In situ polymerization of solid-state polymer electrolytes for lithium metal batteries: a review

The practical application of commercialized lithium-ion batteries (LIBs) currently faces challenges due to using liquid electrolytes (LEs), including limited energy density and insufficient safety performance. The combined application of solid-state polymer electrolytes (SPEs) and lithium metal anodes (LMAs) can address these challenges and has received extensive attention from researchers recently. There are various strategies for assembling SPEs into lithium metal batteries (LMBs), but the most promising strategy is the in situ polymerization strategy. The in situ polymerization strategy can achieve good interfacial contact between SPEs and electrodes, significantly reducing the interfacial resistance. This paper comprehensively reviews the latest in situ polymerization strategies for polymer solid-state lithium metal batteries (PSSLMBs), including the polymer system's design, the polymerization strategy's innovation, and the characterization of the whole cell. We summarize the components of the in situ polymerization system, such as monomers, initiators, lithium salts, and backbone materials, and focus on the methods to improve the ionic conductivity and further enhance the safety performance of SPEs, including strategies such as the addition of inorganic nanoparticles, inorganic-polymer hybridization, and the construction of artificial SEIs. The PSSLMBs prepared by the in situ polymerization strategy have good application prospects and potential to become the next generation of commercialized lithium batteries.