Phase Modulation of MoOx (2 < x < 3) Enables Fast Bidirectional Sulfur Redox in Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) have attracted significant attention due to their high energy density and low cost. However, further progress in this technology is severely hindered by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish redox kinetics of sulfur cathodes. To overcome these challenges, the application of nanocatalysts into the separators of LSBs boosts the LiPS conversion efficiency. In this study, MoOx (2 < x < 3) submicrometer rods with different oxidation levels are fabricated through precise temperature and atmosphere process parameters. The results show that the composite crystal structure material combines the high electrical conductivity of MoO2 with the high catalytic activity of MoO3, and when used to modify the polypropylene separator, it exhibits catalytic activity for the sulfur reduction reaction and the sulfur evolution reaction. The LSBs deliver a discharge specific capacity of 632.8 mAh g–1 at 8 C and maintain stable cycling for 700 cycles at 1 C, with 0.056% capacity decay per cycle. This study provides a pathway for the preparation of bifunctional catalysis with an integrated structure for LSBs.