Unveiling the relationship between the multilayer structure of metallic MoS and the cycling performance for lithium ion batteries.

Molybdenum disulfide (MoS) with a layered structure is a desirable substitute for the graphite anode in lithium ion storage. Compared with the semiconducting phase (2H-MoS), the metallic polymorph (1T-MoS) usually shows much better cycling stability. Nevertheless, the origin of this remarkable cycling stability is still ambiguous, hindering further development of MoS-based anodes. Herein, we assembled multilayered 1T-MoS nanosheets directly on Ti foil to investigate the Li storage mechanism. Based on experimental observation and computational simulation, we found that the cycling stability correlates with the layer number of MoS. Multilayered 1T-MoS can accommodate inserted Li in a ternary compound Li-Mo-S through a reversible reaction, which is favorable for retaining a substantial number of MoS nanodomains upon Li intercalation. These residual MoS nanodomains can serve as an anchor to adhere LiS species, thereby suppressing the "shuttle effect" of polysulfides and enhancing cycling stability. This work sheds light on the development of high-performance anodes based on metallic MoS for LIBs.