Metal Ion Cutting-Assisted Synthesis of Defect-Rich MoS 2 Nanosheets for High-Rate and Ultrastable Li 2 S 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 2- x nanosheet (NS)/ZnS nanoparticle (NP) heterojunction composites on carbon nanofiber skeletons (CNF@MoS 2- x /ZnS) via a simple Ar-ambience annealing. Results show that Zn 2+ ions capture S 2- ions from MoS 2 and form into ZnS NPs, and the MoS 2 NSs lose S 2- ions and become MoS 2- x ones. As sulfur hosts for lithium-sulfur batteries (LSBs), the CNF@MoS 2- x /ZnS-S cathodes deliver a high reversible capacity of 1233 mA h g -1 at 0.1 C and keep 944 mA h g -1 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 2- x NSs significantly improve the chemisorption and catalyze the kinetic process of redox reactions of lithium polysulfides, and the heterojunctions between MoS 2- x NSs and ZnS NPs further accelerate the transport of electrons and the diffusion of Li + ions. Besides, the CNF@MoS 2- x /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.