Amorphous high entropy alloy nanosheets enabling robust Li–S batteries

High-entropy alloys (HEAs) show great potential for catalyzing complex multi-step reactions, but optimizing their parameters, i.e., composition, but also their crystallinity and morphology, remains a significant challenge. In this study, FeCoNiMoW HEAs are synthesized into either amorphous nanosheets (HEANS) or crystalline nanoparticles (HEANP), which are then used to catalyze the lithium–sulfur (Li–S) reaction of Li–S batteries (LSBs). Evaluations in symmetric cells, coin cells, and pouch cells reveal that HEANS significantly enhance LSB performance, achieving initial discharge capacities up to 1632 mAh g−1. The batteries also exhibit excellent cycling stability over 1000 cycles at 3Cand maintain high-rate performance up to 10C with a capacity of 614 mAh g−1. Comprehensive in situ analyses and density functional theory calculations demonstrate that amorphous HEANS provide more active sites, better ionic conductivity and stronger chemical interactions with lithium polysulfides (LiPS). These properties effectively suppress the shuttle effect, promote the complete S8 → Li2S conversion by reducing the impedance of the solid-electrolyte interphase, and accelerate the Li2S4 → Li2S2 step by lowering the nucleation energy barrier. Overall, this study highlights the superior catalytic properties of amorphous 2D HEAs in LSBs and offers new insights into the mechanisms of LiPS conversion.