A gel polymer electrolyte functionalized separator for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries, featuring ultrahigh specific theoretical energy density with low-cost raw materials, have been deemed one of the most promising candidates for next-generation energy storage and conversion devices. However, the shuttle effect of soluble Li polysulfides (LiPSs) has seriously hindered their practical deployment. Herein, we report that tris(pentafluorophenyl)borane (TPFPB) is used to modify the separator (TPFPB/Al₂O₃) for suppressing the shuttle effect of LiPSs. In detail, the introduction of TPFPB induces 1,3-dioxolane solvent ring-opening polymerization to form a gel layer between the S cathode and separator for suppressing the shuttle effect of Li polysulfides, effectively improving the electrochemical performance of Li-S batteries. The Li-S batteries using the TPFPB/Al₂O₃ separator demonstrate outstanding cycling stability and high capacity retention rates. This work provides a useful guideline for separator modification using a functional interface layer to design high-performance Li-S batteries.