High-Entropy Alloy Nanoparticles Encapsulated in Carbon Nanocages Supported by Carbon Fibers as Enhanced Lithium-Sulfur Battery Interlayers.

The shuttle effect, low electrical conductivity, and sluggish reaction kinetics of sulfur significantly limit the practical application of lithium-sulfur (Li-S) batteries. In this study, high-entropy alloy nanoparticles encapsulated in carbon nanocages and supported by carbon fibers (HEA@NC/CF) are prepared as an interlayer material in Li-S batteries to address these challenges. The HEA nanoparticles provide abundant adsorption and catalytic sites. The enhanced surface properties of HEA are essential for accelerating sulfur reactions and inhibiting the shuttle effect. Additionally, the stable and conductive carbon fiber network offers robust support for the interlayer and enhances electron transfer. Meanwhile, the core-shell structure of HEA@NC effectively serves as a "trapping-conversion" reaction space for lithium polysulfides (LiPSs), along with the phase stabilization of HEA, ensuring the cycling stability of cells. These combined advantages lead to significant improvements in the sulfur reaction kinetics, Li diffusion rate, and cycling stability. The Li-S cells assembled with HEA@NC/CF exhibit outstanding performance, retaining a capacity of 1128 mAh g after 300 cycles at 0.2 C and 913 mAh g after 500 cycles at 1.0 C. Furthermore, the cells still deliver a reversible capacity of 773 mAh g even at a high current density of 2.0 C.