ABSTRACT

High-energy Lithium-sulfur (Li-S) batteries are anticipated to be pivotal in next-generation energy storage systems. However, their practical implementation is severely hindered by the shuttling of polysulfides between the sulfur cathode and the lithium metal anode, as well as the safety hazards introduced by the use of liquid electrolytes. To address these challenges, we applied molybdenum disulfide (MoS₂) interlayer onto a polypropylene (PP) separator via electrostatic spraying, leveraging the Lewis acidity of MoS₂ to initiate the ring-opening polymerization of 1,3-dioxolane (DOL). This process effortlessly converted a commercial liquid electrolyte (LE) into a gel polymer electrolyte (GPE) before cycling, enhancing battery safety and effectively protecting lithium anodes. Furthermore, the MoS₂ interlayer plays a key role in capturing lithium polysulfides during cycling. The GPE demonstrates exceptional performance characteristics: it maintains an ionic conductivity of 7.2 × 10^-4 S cm^-1 at 30°C, extends an electrochemical window up to 4.7 V, and achieves a high lithium-ion transference number of 0.7. Moreover, the MoS₂/PP composite separator with the GPE remains stable even at temperatures as high as 200 °C. Consequently, Li-S batteries equipped with GPE display excellent cycle stability, with a capacity retention of 613 mAh g^-1 after 500 cycles at 0.5 C, and achieve a high coulombic efficiency of 98.5%. This research offers an effective approach for developing high-performance and safe Li-S batteries.

Keywords: lithium-sulfur batteries, shuttle phenomenon, in situ polymerization, MoS₂-coated separator