A new fluorine-containing star-branched polymer as electrolyte for all-solid-state lithium-ion batteries

The trade-off between ionic conductivity and mechanical strength is still a great challenge for all-solid-state polymer electrolyte . Herein, a novel structure-controlled fluorine-containing star-branched polymer (HBPS-(PTFEMA- b -PPEGMA) 27 ) with a hyperbranched polystyrene core and polytrifluoroethyl methacrylate-block-poly (ethylene glycol) methyl ether methacrylate arms is synthesized by atom transfer radical polymerization . Combining the good mechanical strength of fluorine-containing segments and flexible property of PEG segments, the prepared HBPS-(PTFEMA- b -PPEGMA) 27 /LiTFSI solid polymer electrolyte can form flexible transparent self-standing membrane and exhibits the high ionic conductivity of 2.4 × 10 −5  S cm -1  at 25 °C, as well as good thermal stability with the thermal decomposition temperature of 374.7 °C. It also possesses a wide electrochemical window of 4.9 V and good interfacial compatibility. Moreover, the Li/LiFePO 4 cell based on this solid state star-branched polymer electrolyte membrane delivers a high discharge capacity of 147.2 mAh g −1 under a current density of 0.1C at 60 °C.