He Jiarui, Bhargav Amruth, Manthiram Arumugam
Department of Mechanical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
ACS Nano. 2021 May 25;15(5):8583-8591. doi: 10.1021/acsnano.1c00446. Epub 2021 Apr 23.
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 transmission electron microscopy, X-ray photoelectron spectroscopy, and 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) Li-S batteries under lean electrolyte conditions with a high sulfur loading of 6.4 mg cm. 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. This work is expected to design highly efficient, cost-effective electrocatalysts for high-performance Li-S batteries.
锂硫（Li-S）电池具有较高的理论比能量，但存在多硫化锂（LiPS）穿梭效应和反应动力学迟缓的问题。Li-S电池中的催化剂被视为改善迟缓动力学并同时减轻LiPS穿梭效应的基石。在此，一种具有成本效益的六方密堆积（hcp）相铁镍合金被证明可作为一种高效的电催化剂，以促进Li-S电池中的LiPS转化反应。重要的是，通过将电化学结果与透射电子显微镜、X射线光电子能谱和X射线衍射表征相结合，全面揭示了铁镍对LiPS转化的电催化机制。受益于良好的催化性能，铁镍合金在贫电解质条件下、硫负载量为6.4 mg/cm²时，可使Li-S电池具有长寿命（超过800次循环）和高面积容量（6.1 mA h/cm²）。令人印象深刻的是，采用铁镍/硫阴极制造的软包电池在实际所需条件下、低电解质/硫（E/S）比为4.5 μL/mg时，实现了稳定的循环性能。这项工作有望为高性能Li-S电池设计出高效、经济的电催化剂。
