Mitigation of Polysulfide Shuttling in Lithium-Sulfur Batteries Utilizing Vanadium Pentoxide/Polypyrrole Nanocomposite Separators

Lithium-sulfur (Li−S) batteries are promising energy storage devices due to their high theoretical energy density and cost-effectiveness. However, the shuttle effect of polysulfides during the charging and discharging processes leads to a rapid decline in capacity, thereby restricting their application in energy storage. The separator, a crucial component of Li−S batteries, facilitates the transport of Li⁺ ions. However, the large pores present on the surface of the separator are insufficient to prevent the shuttling effect of polysulfides. This paper proposes a straightforward coating method to introduce a vanadium pentoxide (V₂O₅) /polypyrrole (PPy) functional coating on the surface of a conventional polymer separator. The unique composition of the V₂O₅/PPy layer plays an essential role in effectively preventing the bidirectional movement of polysulfides and the subsequent formation of inactive sulfur. Compared to those using polypyrrole separators,when equipped with a V₂O₅/PPy separator, the capacity retention after 100 cycles was recorded at 98 %, with a measured rate of capacity degradation at just 0.016 %, despite the sulfur content being as high as 1.84 mg cm⁻². Furthermore, after 400 cycles at 1 C, the capacity retention rate reached 57.6 %. The thoughtful design of this modified separator represents an effective strategy for improving the performance of Li−S batteries.