Metal Ion Cutting-Assisted Synthesis of Defect-Rich MoS Nanosheets for High-Rate and Ultrastable LiS Catalytic Deposition.

Active metal ions often show a strong cutting effect on the chemical bonds during high-temperature thermal processes. Herein, a one-pot metal ion cutting-assisted method was adopted to design defect-rich MoS nanosheet (NS)/ZnS nanoparticle (NP) heterojunction composites on carbon nanofiber skeletons (CNF@MoS/ZnS) via a simple Ar-ambience annealing. Results show that Zn ions capture S ions from MoS and form into ZnS NPs, and the MoS NSs lose S ions and become MoS ones. As sulfur hosts for lithium-sulfur batteries (LSBs), the CNF@MoS/ZnS-S cathodes deliver a high reversible capacity of 1233 mA h g at 0.1 C and keep 944 mA h g at 3 C. Moreover, the cathodes also show an extremely low decay rate of 0.012% for 900 cycles at 2 C. Series of analysis indicate that the MoS NSs significantly improve the chemisorption and catalyze the kinetic process of redox reactions of lithium polysulfides, and the heterojunctions between MoS NSs and ZnS NPs further accelerate the transport of electrons and the diffusion of Li ions. Besides, the CNF@MoS/ZnS-S LSBs also show an ultralow self-discharge rate of 1.1% in voltage. This research would give some new insights for the design of defect-rich electrode materials for high-performance energy storage devices.