Hierarchical NiS<sub>2</sub>/1T-MoS<sub>2</sub> Nanocomposite\nfor Stable Lithium Sulfur Batteries

The practical applications of lithium–sulfur (Li–S)\nbatteries have been significantly impeded by the heavy shuttle effect\nand slow bidirectional conversion of lithium polysulfides (LiPSs).\nIn this study, a hierarchical NiS<sub>2</sub>/1T-MoS<sub>2</sub> nanocomposite\nis utilized as a functionalized separator modifier to overcome the\nchallenges. The MoS<sub>2</sub> nanosheets are vertically and uniformly\naligned on the surface of NiS<sub>2</sub> microspheres, constructing\na hierarchical yolk–shell structure. The NiS<sub>2</sub> support\nnot only significantly reduces the agglomeration of MoS<sub>2</sub> nanosheets but also effectively stabilizes their 1T-phase structure,\nwhich is highly desirable for high-performance Li–S batteries.\nThe Li–S battery with the NiS<sub>2</sub>/MoS<sub>2</sub>–CNT-modified\nseparator delivers an excellent initial specific capacity of 1228\nmA h g<sup>–1</sup> at 0.2 C with a high-capacity retention\nof 85% over 100 cycles. It even achieves a discharge capacity of 722\nmA h g<sup>–1</sup> at 5 C. Furthermore, it maintains remarkable\ncycling stability with only 0.051% capacity decay per cycle during\nthe long-term cycles at 1 C. This study not only provides a viable\nscheme for separator modifier design toward advanced Li–S batteries\nbut also offers a universal route for stabilizing the 1T-phase structure\nof MoS<sub>2</sub>.