Metal Ion Cutting-Assisted Synthesis of Defect-Rich MoS₂ Nanosheets for High-Rate and Ultrastable Li₂S Catalytic...

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- nanosheet (NS)/ZnS nanoparticle (NP) heterojunction composites on carbon nanofiber skeletons (CNF@MoS_2-/ZnS) via a simple Ar-ambience annealing. Results show that Zn²⁺ ions capture S^2- ions from MoS₂ and form into ZnS NPs, and the MoS₂ NSs lose S^2- ions and become MoS_2- ones. As sulfur hosts for lithium-sulfur batteries (LSBs), the CNF@MoS_2-/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- NSs significantly improve the chemisorption and catalyze the kinetic process of redox reactions of lithium polysulfides, and the heterojunctions between MoS_2- NSs and ZnS NPs further accelerate the transport of electrons and the diffusion of Li⁺ ions. Besides, the CNF@MoS_2-/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.