中空硫球-MoS₂/rGO 材料的制备及其在锂硫电池中的应用

Lithium-sulfur batteries have become a promising energy storage device due to the advantages of high theoretical energy density and high theoretical specific capacity. However, the practical application has been impeded by the insulation of the active material sulfur and the lithium polysulfide, the considerable volume expansion effect during cycling, and the “shuttle effect” caused by the dissolution of polysulfide. Herein, the hollow sulfur spheres (HS) were synthesized by low temperature liquid phase method, while the nanoflower MoS₂/reduced graphene oxide (MoS₂/rGO) was prepared by the hydrothermal method. Then, MoS₂/rGO was coated on the surface of HS to obtain HS-MoS₂/rGO composite cathode material. The crystal structure and morphology of the composites were characterized by XRD, SEM, TEM and XPS, while the electrochemical performance of the HS-MoS₂/rGO and HS-rGO cathodes was tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The results indicate that MoS₂/rGO shows strong polysulfide adsorption capability and high catalytic activity to limit the shuttle of polysulfides. Meanwhile, the unique hollow structure of the sulfur spheres can alleviate volume expansion to maintain the structural stability. Consequently, the HS-MoS₂/rGO cathode achieves excellent rate performance and cycling stability of lithium-sulfur batteries.