In situ polymerization-driven quasi-solid electrolytes for Li-metal batteries

Abstract

Li-metal batteries (LMBs) have emerged as the most promising energy storage technology to achieve high energy density exceeding 400 W h kg⁻¹. However, the conventional liquid electrolytes in LMBs present significant challenges, including severe reactivity with Li metal anodes and substantial safety risks. Quasi-solid electrolytes (QSEs), which combine the advantages of both solid and liquid electrolytes, have been identified as an ideal alternative for practical LMB applications. In particular, QSEs fabricated through in situ polymerization strategies offer enhanced interfacial compatibility, simplified manufacturing processes, reduced production costs, and represent one of the most commercially viable pathways for QSE development. This review provides a comprehensive analysis of in situ polymerization-driven QSEs and their application in LMBs. QSEs are systematically categorized based on the polymerization mechanisms of the polymer matrix, including free radical, cationic, anionic, and electrochemical polymerizations. Furthermore, the strategies for improving the performance of QSE-based LMBs are thoroughly discussed, with a focus on enhancing flame-retardant properties, high-voltage compatibility, and low-temperature operation. Finally, the review concludes with a critical assessment of the current state and future prospects of QSE-based LMBs, providing valuable insights into the future development of safer and more efficient energy storage systems.