Fluorine-containing triblock copolymers as solid-state polymer electrolytes for lithium metal batteries

Block copolymer electrolytes (BCPEs) are promising candidates for solid-state lithium battery applications because they can achieve improved mechanical performance and conductivity simultaneously. In this report, we report on fluorine-containing ABA triblock copolymer electrolytes (FBCPEs) with A blocks of perfluoroalkyl pendants and B blocks of poly(ethylene oxide) (PEO). It is found that fluorine-containing blocks endows considerable mechanical strength, high lithium ion transference number of tLi+ = 0.41, and wide electrochemical stability window up to 4.9 V to FBCPEs. In addition, FBCPEs can also participate in forming fluorinated solid electrolyte interphase (SEI), and thus serves to enhance the cycle stability of batteries. Combination of these excellent properties leads to the LiFePO4/FBCPEs/Li cells with excellent cycling performance and rate capability. The cycle results of the assembled LiNi0.6Co0.2Mn0.2O2/FBCPEs/Li cells indicate that FBCPEs have potential for application in high-voltage battery systems.