Enhancing the redox kinetics of Li-S cells with Fe-doped MoS₂ and WO₃ intercalated multilayer reduced graphene oxide as a multifunctional mediator

Although lithium-sulfur (Li-S) batteries possess a theoretically high energy density, they face substantial limitations that hinder their commercialization and practical utilization. Two limitations are the slow kinetics of sulfur reactions and the lithium polysulfide (LiPSs) shuttle phenomenon. This research has advanced Li-S batteries by synthesizing and introducing a Fe-doped MoS₂ and WO₃ intercalated multilayer rGO composite (Fe-MoS₂-WO₃@rGO) as an electrocatalyst. WO₃ attaches to polysulfides, stopping dissolution into the electrolyte, while the MoS₂ promotes electron transport and strong binding at the separator. Doping the iron (Fe) element may expose additional anchoring active sites, which reduce the shuttle effect. Thus, the Fe-MoS₂-WO₃@rGO could balance polysulfide immobilization and catalytic activity, leading to high performance of the cell. The Li-S cell using a separator consisting of Fe-MoS₂-WO₃@rGO/PP delivers a significant capacity of 442 mAh g⁻¹ after the 1000th cycle at 1.0 C. Moreover, under a substantial current of 5.0 C, the cell consistently retains a 415 mAh g⁻¹ capacity for 700 cycles. Furthermore, the tri-layer sulfur cathode cell provides a capacity of 6.1 mAh cm⁻² after completing the 100th cycle (under the condition of 8.19 mg cm⁻² sulfur loading). The findings of this study demonstrate the successful construction and utilization of the Fe-MoS₂-WO₃@rGO functional mediator in Li-S cells, resulting in enhanced electrochemical performance. Besides, it facilitates the development of an innovative multi-layer cathode technology to boost the efficiency of Li-S cells.