Enhancing the electrochemical performance and safety of lithium-ion battery via fluorinated MOF-based multifunctional separator

To meet high-standard requirements for next generation lithium-ion batteries (LIBs), reinforce the functions of separator are becoming imperative and urgent. In this work, we successfully fabricated a multifunctional separator, namely, UIO-66-F@PP, which enabled the test battery to achieve a significant improvement in electrochemical performance and safety. The modified separator UIO-66-F@PP can finely regulate the ion transfer by facilitating the Li + transport due to the orderly porous structure and the negatively charged functional group (−F), resulting in a higher ion conductivity ( σ ) of 0.91 mS cm −1 and a larger Li + transference number ( t Li + ) of 0.78. By analyzing the Sand’s time ( t sand ), it was found that the lithium dendrite was suppressed by the modified separator UIO-66-F@PP. Besides, the symmetric battery Li//Li assembled with UIO-66-F@PP exhibited a stable lithium plating/stripping cycle over 2000 h. The battery of LFP//Li with UIO-66-F@PP demonstrated an excellent rate performance with a discharging specific capacity of 114 mAh g −1 at 10C. Moreover, the burning and heat shrinkage tests showed that the modified separator UIO-66-F@PP has a self-extinguishing character and a high thermal stability even at 190 °C, indicating that the modified separator has the capability to endow the LIBs with high safety.