Abstract: A multifunctional LiBr/MoO₃/PE composite separator was prepared by introducing molybdenum trioxide (MoO₃) and lithium bromide (LiBr) coatings onto polyethylene (PE) separators. The structure and morphology of the separator were characterized by X-ray diffraction and scanning electron microscope, and cyclic voltammetry, electrochemical impedance and charge discharge performance testing were used to investigate the effect of LiBr/MoO₃/PE separator coated with a modified layer on the stability of lithium metal negative electrodes and the performance of lithium sulfur batteries. The results show that LiBr increases the solubility of lithium polysulfide (LiPSs), and the MoO₃ layer has a chemical adsorption effect on LiPSs, which can improve the utilization rate of active substance sulfur and suppress the shuttle effect of Li-S batteries. The Li-Li symmetric battery with LiBr/MoO₃/PE as the separator has a stable cycle time of 1 600 h at a current density of 0.6 mA/cm² and a capacity of 1 (mA·h)/cm². The initial discharge specific capacity of the lithium sulfur battery at 0.2 C can reach 1 229.2 (mA·h)/g, and the specific capacity after 500 charge discharge cycles is 628 (mA·h)/g.

Key words: molybdenum trioxide (MoO₃), lithium bromide(LiBr), LiBr/MoO₃/PE separator, lithium sulfur battery, electrochemical property