Hierarchical NiS2/1T-MoS2 Nanocomposite for Stable Lithium Sulfur Batteries

The practical applications of lithium–sulfur (Li–S) batteries have been significantly impeded by the heavy shuttle effect and slow bidirectional conversion of lithium polysulfides (LiPSs). In this study, a hierarchical NiS2/1T-MoS2 nanocomposite is utilized as a functionalized separator modifier to overcome the challenges. The MoS2 nanosheets are vertically and uniformly aligned on the surface of NiS2 microspheres, constructing a hierarchical yolk–shell structure. The NiS2 support not only significantly reduces the agglomeration of MoS2 nanosheets but also effectively stabilizes their 1T-phase structure, which is highly desirable for high-performance Li–S batteries. The Li–S battery with the NiS2/MoS2–CNT-modified separator delivers an excellent initial specific capacity of 1228 mA h g–1 at 0.2 C with a high-capacity retention of 85% over 100 cycles. It even achieves a discharge capacity of 722 mA h g–1 at 5 C. Furthermore, it maintains remarkable cycling stability with only 0.051% capacity decay per cycle during the long-term cycles at 1 C. This study not only provides a viable scheme for separator modifier design toward advanced Li–S batteries but also offers a universal route for stabilizing the 1T-phase structure of MoS2.