EC modified PEO/PVDF-LLZO composite electrolytes for solid state lithium metal batteries

The polymer-ceramic composite electrolytes have great application potential for next-generation solid state lithium batteries, as they have the merits to eliminate the problem of liquid organic electrolytes and enhancing chemical/electrochemical stability. However, polymer-ceramic composite electrolytes show poor ionic conductivity, which greatly hinders their practical applications. In this work, the addition of plasticizer ethylene carbonate (EC) into polymer-ceramic composite electrolyte for lithium batteries effectively promotes the ionic conductivity. A high ionic conductivity can be attained by adding 40 wt% EC to the polyethylene oxide (PEO)/polyvinylidene fluoride (PVDF)-Li7La3Zr2O12 (LLZO) based polymer-ceramic composite electrolytes, which is 2.64 × 10−4 S cm−1 (tested at room temperature). Furthermore, the cell assembled with lithium metal anode, this composite electrolyte， and LiFePO4 cathode can work more than 80 cycles at room temperature (tested at 0.2 C). The battery delivers a high reversible specific capacity after 89 cycles, which is 119 mAh g−1.