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

Abstract

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 NiS 2 /1T-MoS 2 nanocomposite is utilized as a functionalized separator modifier to overcome the challenges. The MoS 2 nanosheets are vertically and uniformly aligned on the surface of NiS 2 microspheres, constructing a hierarchical yolk−shell structure. The NiS 2 support not only significantly reduces the agglomeration of MoS 2 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 NiS 2 /MoS 2 −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 MoS 2 .