Synergistic Electrocatalysis of Polysulfides by a Nanostructured VS4-Carbon Nanofibers Functional Separator for High-Performance Lithium-Sulfur Batteries

The sluggish redox kinetic and severe shuttle effect remain the key issues for the application of lithium sulfur batteries, resulting in a low sulfur utilization and fast capacity fading. Herein, a nanostructured VS4 anchored on defect-rich carbon nanofibers is coated on the commercial separator as both a physical blocks to mitigate the shuttle effects and an electrocatalyst to enhance the reaction kinetics of polysulfides/Li2S. Besides, polar nanostructured VS4 shows a high affinity to polysulfides and conductive CNFs network serves as “second collector” to trap and reutilize the active materials. The functional coating layer also provides rich defects for the dispersion and stabilization of Li2S. When the VS4-CNFs functional separator based on a high-sulfur content (80wt%) cathode was applied in Li-S batteries, delivering a high initial capacity of 1135mAh g-1 at 0.2C and a superior rate capacity of 780mAh g-1 at 2C. Even under a higher rate (5C), it still delivers a stable capacity of 300mAh g-1 over 1000 cycles with a high coulombic efficiency of 95%.