Sulfide-based MOF material modification of separators: enhancing performance of lithium-sulfur batteries by suppressing shuttle effect

Lithium-sulfur batteries (LSBs) are extensively studied owing to their high theoretical capacity and low cost. However, the shuttle effect of lithium-sulfur batteries hinders their development. In this study, we obtained a modified separator to inhibit the shuttle effect through physical and chemical adsorption. The CoS2 nanosheets (CSNS) derived from a cobalt-based metal-organic framework (Co-MOF) were synthesized by a simple two-step method involving hydrothermal sulfurization and thermal decomposition. The material was then coated onto a Polypropylene (PP) separator using vacuum filtration and assembled into a LSB for systematic testing and research of its electrochemical performance and mechanism. Thanks to the intrinsic polarity of the CSNs and more active sites brought by the Co-MOF material, the modified separator has strong chemical adsorption and catalytic effects on polysulfides, anchoring and accelerating their conversion. When using the CSNs-PP separator, the LSB achieved a high initial capacity of 1002.4 mAh g−1 at 1 C, with only a 0.099% decay per cycle after 500 cycles. The modified separator effectively alleviating the shuttle effect, reducing internal resistance, weakening reaction polarization, and improving the specific capacity, stability, and reversibility of the battery.