Solid polymer electrolytes based on poly(ionic liquid-co-ethylene oxide) for room-temperature solid-state lithium batteries

Solid polymer electrolytes (SPEs) possessing attractive electrochemical performance are essentially required for lithium-ion batteries (LIBs). Herein, a poly(imidazolium ionic liquid-co-ethylene oxide) (PILEO) is synthesized via a facile one-pot poly-Radziszewski reaction. The incorporated PILEO can reduce the crystallinity of the obtained SPEs, and hence facilitates lithium ion migration. It is demonstrated that the developed PILEO-60 SPE, without adding any plasticizers or inorganic fillers, exhibits a high ionic conductivity of 1.78 x 10-4 S cm-1 at 25 celcius and a wide electrochemical stability window of 4.9 V (vs. Li/Li+). The assembled LFP/PILEO-60/Li cell possesses a high discharge capacity (140 mAh g-1 at 25 celcius), good cycling performance (90.3% of capacity retention after 100 cycles), and stable coulombic efficiency (99.7%). In combination with the industrially feasible synthetic procedure of PILEO, this work provides a facile and effective strategy for the fabrication of high-performance LIBs.