Selective Adsorption-Catalysis Sites of Lithium Polysulfides Induced by the Competition between Spin Polarization and Electronegativity in High-Entropy Alloy Electrocatalysts.

Abstract

High-entropy alloy (HEA) electrocatalysts have attracted increasing attention for improving sulfur reaction kinetics and anchoring lithium polysulfides (LiPSs) in lithium-sulfur batteries (LSBs). However, fundamentally understanding the relationship between the components of HEAs and the adsorption catalysis of LiPSs remains a challenge. Here, FeCoNiMnRu HEAs are employed as a model to first disclose the selective adsorption-catalysis effect of LiPSs, induced by the competition between spin polarization and electronegativity of Ni-Co-Ru sites in HEAs. By correlating the electron structure, we find that the high-electronegativity Ru sites induce electron transfer from Co sites, generating local electron delocalization, while the Ni sites adopt a high-spin state. Specifically, high-spin Ni sites with stronger Ni-S covalency can sustainably anchor LiPSs, while electron-delocalized Co-Ru sites function better in LiPS conversion. Consequently, benefiting from the selective adsorption-catalysis effect of Ni-Co-Ru sites, LSBs with FeCoNiMnRu/CNF interlayers deliver exceptional cycling performance (0.06% per cycle over 500 cycles at 1 C, and an outstanding areal capacity of 11.2 mAh cm^-2 at 0.1 C). This work offers key insights for extending HEAs electrocatalysts to enable high-performance LSBs.