Unprecedented Impact of Main Chain on Comb Polymer Electrolytes Performances

Abstract Comb‐like polymers are one of the most auspicious candidates for building fully amorphous and highly conductive solid polymer electrolytes (SPEs), which are essential components to develop high‐performance solid‐state rechargeable lithium metal batteries (RLMBs). Herein, two kinds of comb‐like polymers containing either polymethacrylate or polyacrylate as main chains are comparatively investigated, aiming to illustrate the role of polymer backbones on the basic properties of SPEs. The comb‐like SPEs are fully amorphous, and exhibit significantly higher ionic conductivities at room temperature over traditional poly(ethylene oxide) (PEO)‐based ones (close to 10 −4 S cm −1 ). In particular, the polymethacrylate‐based SPEs show significantly improved interfacial stability against lithium metal electrode compared with the polyacrylate‐based ones, due to the elimination of electrochemically labile C−H moiety at the alpha position of the carbonyl group (C=O) in the polyacrylate structure. The present work provides not only a new family of SPEs consisting of lithium bis(fluorosulfonyl)imide (LiFSI) and poly(methoxy‐polyethylene glycol methacrylate) (i.e., LiFSI/P(CH 3 ‐MPEGMA)), with high ionic conductivities at room temperature but also insights into developing lithium‐metal‐friendly SPE for safe RLMBs.