Fast Li+ Transport Polyurethane-Based Single-Ion Conducting Polymer Electrolyte with Sulfonamide Side chains in the Hard Segment for Lithium Metal Batteries

Single-ionconducting polymer electrolytes (SICPEs) are consideredas one of the most promising candidates for achieving lithium metalbatteries (LMBs). However, the application of traditional SICPEs ishindered by their low ionic conductivity and poor mechanical stability.Herein, a self-standing and flexible polyurethane-based single-ionconductor membrane was prepared via covalent tethering of the trifluoromethanesulfonamideanion to polyurethane, which was synthesized using a facile reactionof diisocyanates with poly(ethylene oxide) and 3,5-diaminobenzoicacid (or 3,5-dihydroxybenzoic acid). The polymer electrolyte exhibitedexcellent ionic conductivity, mechanical properties, lithium-ion transferencenumber, thermal stability, and a broad electrochemical window becauseof the bulky anions and unique two-phase structures with lithium-ionnanochannels in the hard domains. Consequently, the plasticized electrolytemembrane showed exceptional stability and reliability in a Li||Lisymmetric battery. The assembled LiFePO4||Li battery exhibitedan outstanding capacity (& SIM;180 mA h g(-1)),Coulombic efficiency (>96%), and capacity retention. This researchprovides a promising polymer electrolyte for high-performance LMBs.