Polyurethane-based polymer electrolytes for lithium Batteries: Advances and perspectives

Polymer electrolytes (PEs) have been widely regarded as an effective approach to eliminate most of the potential safety hazards encountered in traditional liquid electrolytes for lithium batteries (LBs). Substantial research efforts have been devoted to exploiting excellent performance PE systems, including poly(ethylene oxide) (PEO), polyurethane (PU), polysiloxane (PS), polyvinylidene fluoride (PVDF) and polycarbonate (PC)-based PEs. Among them, PU-based PEs have attracted increasing interests due to their flexibility of structure manipulation, excellent mechanical strength, facile modification, high thermal and electrochemical stability. However, to date, separated and detailed reviews on the progress of PU-based PEs are rarely reported. In this review, we comprehensively summarize the key progress on PU-based PEs from the perspective of flexible structure design strategies, basic electrochemical/mechanical properties, typical modification methods, specific functions, and their potential applications in LBs. Furthermore, synthesis routes of PUs and perspectives of PU-based PEs are also discussed. It is believed that this review will be of great guiding significance for exploiting high performance PU-based PEs for next-generation LBs.