High-Energy-Density, Long-Life Lithium–Sulfur Batteries with Practically Necessary Parameters Enabled by Low-Cost Fe–Ni Nanoalloy Catalysts

Lithium–sulfur (Li–S) batteries possess high theoretical specific energy but suffer from lithium polysulfide (LiPS) shuttling and sluggish reaction kinetics. Catalysts in Li–S batteries are deemed as a cornerstone for improving the sluggish kinetics and simultaneously mitigating the LiPS shuttling. Herein, a cost-effective hexagonal close-packed (hcp)-phase Fe–Ni alloy is shown to serve as an efficient electrocatalyst to promote the LiPS conversion reaction in Li–S batteries. Importantly, the electrocatalysis mechanisms of Fe–Ni toward LiPS conversion is thoroughly revealed by coupling electrochemical results and post mortem transmission electron microscopy, X-ray photoelectron spectroscopy, and in situ X-ray diffraction characterization. Benefiting from the good catalytic property, the Fe–Ni alloy enables a long lifespan (over 800 cycles) and high areal capacity (6.1 mA h cm–2) Li–S batteries under lean electrolyte conditions with a high sulfur loading of 6.4 mg cm–2. Impressively, pouch cells fabricated with the Fe–Ni/S cathodes achieve stable cycling performance under practically necessary conditions with a low electrolyte/sulfur (E/S) ratio of 4.5 μL mg–1. This work is expected to design highly efficient, cost-effective electrocatalysts for high-performance Li–S batteries.