High performing single-ion conducting block copolymer electrolytes based on poly(ethylene oxide) and specifically designed methacrylic sulfonamide

In the field of polymer electrolytes, new single-ion conductors have attracted increasing interest in recent years, mainly because of their intrinsic safety and peculiar chemical structure that can be tailored as desired to display unique properties, such as tLi+ ≈ 1. Nevertheless, their practical application is still limited by low ionic conductivity (σ, far below 10–5 S cm–1 at 25 °C). Herein, the preparation and characterization of new families of single-ion conducting copolymers based on the specifically designed lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethylsulfonyl)imide (LiMTFSI) anionic monomer is described. RAFT polymerization was employed to prepare well-defined anionic di- and tri-block copolymers comprising poly(LiMTFSI) and poly(ethylene oxide) blocks. Block copolymers were semi crystalline with a single Tg. They showed very high σ (≈ 10–4 S cm–1 at 70 °C), impressive t+ ≈ 0.91 and wide 4.5 V electrochemical stability, combined with long lifetime up to 300 cycles and outstanding rate performance in LiFePO4/Li cells at different temperatures.