The effects of PVB additives in MOFs-based solid composite electrolytes for all-solid-state lithium metal batteries

All solid-state lithium-ion batteries (ASSLBs) are thought to benefit from using solid composite electrolytes (SCEs) to increase their energy density and safety. In this study, we firstly introduce the PVB additives to SCEs and prepared a SCE composed of a mixture of nanostructured MOFs (UiO-67), PVDF-HFP, PVB, and LiTFSI. Electrochemical characterizations of the SCEs (EIS, LSV, CV and battery test) were also conducted. The SCE UBP-2 (PVB:PVDF-HFP = 1:10) shows a high lithium-ion transference number (tLi+ =0.72) and good ionic conductivity (3.27×10−4 S cm−1 at 60 °C). A symmetric Li cell with SCE UBP-2 can be continuously cycled at 0.1 mA cm−2 for more than 2500 h without experiencing a short circuit. The full cell (LiFePO4/UBP-2/Li) also maintained a high reversible discharge capacity of 154.9 mAh g−1 at 0.1C after 200 cycles at 60 °C. At 3C, a capacity of around 100 mAh g−1 was also achieved. This work might help to enhance the development of the forthcoming all solid-state batteries.