Sulfur-Modified Amorphous Noble-Metal-Free High-Entropy Alloy Ultra-Thin Nanosheets for Low-Overpotential and Long-Lifespan Li-O₂ Batteries.

Abstract

While noble-metal-free high-entropy alloys (NHEA) represent promising low-cost catalysts for Li-O₂ batteries, their catalytic capability is limited by the low metal-site utilization and unfavorable electronic structure inherent in conventional configurations. Herein, we report a novel design for a CuFeCoNiMn-NHEA catalyst, characterized by its entirely amorphous structure and the Metal─S bonds (especially Ni─S) introduced by S-doping. The successful synthesis of this catalyst relies on a rapid low-temperature strategy, where the 5°C reaction temperature limits atomic diffusion and long-range ordering, while the sub-1-min duration kinetically traps the atoms in a disordered state. Within this architecture, the ultra-thin 2D morphology, disordered atomic arrangement, and unsaturated atomic coordination offer abundant active sites by eliminating constraints from crystal planes and boundaries; simultaneously, the Metal─S bonds significantly optimize the electronic structure. The electronegativity gradient between metal and S induces electron delocalization at metal sites, which lowers the d-band center and optimizes the adsorption energy of ^*LiO₂ intermediates, thereby accelerating the redox kinetics. Meanwhile, strengthened Metal─S coordination elevates metal vacancy formation energies by 1-3 times, which suppresses atomic leaching to improve structural stability. Therefore, our unique catalyst achieves a low overpotential (0.48 V), and an exceptional lifespan (452 cycles), significantly outperforming most reported noble-metal-free catalysts.