Interspersing Partially Oxidized VC Nanosheets and Carbon Nanotubes toward Multifunctional Polysulfide Barriers for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have attracted much attention attributed to their high theoretical energy density, whereas the parasitic shuttling behavior of lithium polysulfides (LiPS) hinders this technology from yielding practically competitive performance. Targeting this critical challenge, we develop an advanced polysulfide barrier by modifying the conventional separator with CNTs-interspersed VC/VO nanosheets to alleviate the shuttle effect. The partial oxidization of VC MXene constructs the VC/VO composite with VO nanoparticles uniformly dispersed on few-layered VC nanosheets, which synergistically and concurrently improves the sulfur confinement and redox reaction kinetics. Moreover, the interstacking between the 1D CNTs and the 2D VC/VO not only prevents the agglomeration of nanosheets for efficient exposure of active interfaces but also constructs a robust conductive network for fast charge and mass transfers. The Li-S cells with VC/VO/CNTs-modified separator realize a high initial capacity (1240.4 mAh g at 0.2 C), decent capacity retention (82.6% over 500 cycles), and favorable areal capacity (5.9 mAh cm) at a raised sulfur loading (6.0 mg cm). This work affords a unique multifunctional separator design toward durable and efficient sulfur electrochemistry, holding great promise for improving the electrochemical properties of Li-S batteries.