Local fluorinated functional units enhance Li+ transport in acrylate-based polymer electrolytes for lithium metal batteries

Abstract

Fluorinated polymer matrix emerges as a promising candidate owing to their enhanced anti-oxidation ability, but their application is plagued by the relatively low ion conduction ability and the ambiguous ionic conduction mechanism in the fluorinated polymer electrolytes (PEs). Herein, a series of acrylate-based electrolytes with different fluorinated functional units (fluorinated-FUs) of poly(ethyl methacrylate) electrolyte (0F PE), poly(trifluoroethyl methacrylate) electrolyte (3F PE) and poly(hexafluorobutyl methacrylate) electrolyte (6F PE) were investigated. Beneficial from the long fluorinated-FUs in the side chain, the 6F PE exhibits improved both ionic conductivity of 4.0×10−4 S cm−1 and Li+ transference number of 0.65 at 25 °C, which are superior to those of the 0F PE and the 3F PE. The enhanced ion conduction mechanism was clarified via combining the theoretical calculations and experimental data, where the integration of local fluorinated-FUs provides additional coordinating sites for the continuous Li+ migration and regulates the ion transporting pathways. This work demonstrates that the regulation of local fluorinated-FUs can provide a promising strategy for achieving high performance PEs applied in solid-state batteries.