Research Progress and Prospects of Poly(Ionic Liquid)s for High‐Performance Lithium Batteries

Poly(ionic liquid)s (PIL) are a class of highly designable functional polymers that integrate the high ionic conductivity, a wide electrochemical stability window, and intrinsic flame retardancy of ionic liquids, positioning them as leading candidates to overcome the safety bottlenecks of conventional lithium batteries. This review systematically summarizes recent advances in PIL across three critical application areas: homogeneous solid electrolytes, composite solid electrolytes, and multifunctional electrode binders. It highlights PIL molecular design strategies, compositing approaches with flexible polymers, nanoparticle composites, and porous framework composites, as well as the performance advantages of bifunctional binders in both cathodes and anodes. Furthermore, this review provides an in-depth analysis of key challenges, including the inherent trade-off between ionic conductivity and mechanical strength, interfacial degradation over prolonged cycling, and high costs associated with large-scale manufacturing. Future directions are outlined with a focus on precise molecular engineering and in situ interfacial engineering, offering a forward-looking reference for the design of high-safety, high-performance solid-state lithium batteries.