In-situ collaborative design of crosslinking and fluorination toward poly(1,3-dioxolane) for high-performance semi-solid lithium metal batteries

In-situ poly(1,3-dioxolane) (PDOL)-based electrolyte has received extensive attention in the research of lithium metal batteries due to its high stability to lithium anode and simple processing. However, it is still faced with defects such as low intrinsic ionic conductivity, a narrow electrochemical window, and poor thermal stability. A crosslinking and fluorination molecular design strategy toward PDOL is proposed to tackle the issues above. The amorphous crosslinked structure effectively improves ionic conductivity by inhibiting long-chain crystallization. Especially, the antioxidant –CF3 groups, stable crosslinked structure, and reduced terminal hydroxyl groups significantly enhance the electrochemical oxidation stability with a superb high-voltage window of 4.7 V. In addition, the designed electrolyte also exhibits obviously improved thermal stability with no deformation at 120 °C for 5 min. Furthermore, the semi-solid NCM811||Li batteries exhibit a favourable capacity retention of 88.8 % after 150 cycles at 0.5 C. Even assembled with NCM622 cathode working at 4.5 V, the semi-solid batteries can still show a satisfactory capacity retention of 85.3 % after 100 cycles at 0.5 C. Also, a 0.1 Ah NCM811||Li pouch cell with active materials loading of 9 mg/cm2 demonstrates satisfactory cycling stability and working ability, which shows promising practical application prospects.