Expediting Polysulfide Anchoring by Fe3O4/Reduced Graphene Oxide Composite for High-Performance Lithium-Sulfur Batteries

The inherent low conductivity of sulfur, sluggish redox kinetics, and the challenge of maximizing active material utilization are the bottlenecks for practical implementation in lithium-sulfur (Li−S) battery technology. Herein, a low-cost Fe₃O₄-rGO that serves as both a sulfur host matrix and an electrocatalytic interlayer in a Li−S battery has been synthesized. With the merit of high specific surface area, Fe₃O₄-rGO offers high sulfur loading (80 wt. %) and sufficient space to accommodate sulfur volume expansion during the redox reaction. The symmetric cell experiment demonstrated that Fe₃O₄ in the rGO structure promotes the lithium polysulfide (LPS) redox conversion. The Li−S battery is constructed using the Fe₃O₄-rGO@S as the cathode and Fe₃O₄-rGO as the interlayer, demonstrating an impressive specific capacity of 1258 mAh g⁻¹ at 0.1 C and the battery retained 76 % of its capacity after 400 cycles at 0.5 C. This study also explores the confinement of LPS on the Fe₃O₄-rGO@S_Fe₃O₄-rGO cathode and interfacial redox kinetics by dynamic electrochemical impedance spectroscopy. This work presents a cost-effective method for improving the catalytic conversion of lithium polysulfides, which can contribute to the development of high-performance lithium-sulfur batteries.