Zhang Kai, Li You, Wang Hongyu, Zhang Zisheng, Liu Guihua, Zhang Yongguang
Hebei Provincial Key Laboratory of Green Chemical Technology and High Efficient Energy Saving, Tianjin Key Laboratory of Chemical Process Safety, School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, People's Republic of China.
Department of Chemical and Biological Engineering, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
Nanotechnology. 2021 Dec 23;33(11). doi: 10.1088/1361-6528/ac3703.
The development of efficient sulfur host materials to address the shuttle effect issues of lithium polysulfides (LiPSs) is crucial in the lithium-sulfur (Li-S) batteries but still challenging. In the present study, a novel yolk shell structured MgCo-LDH/ZIF-67 composite is designed as Li-S battery cathode. In this composite, the shell layer is MgCo layered double hydroxide constructed by partially etching ZIF-67 nanoparticle by Mg, and the core is the unreacted ZIF-67 particle. The unique yolk shell structure not only provides abundant pores for sulfur accommodation, but also facilitates the electrolyte penetration and ion transport. The ZIF-67 core exhibits strong polar adsorption to LiPSs through the Lewis acid-base interactions, and the micropores/mesoporous can further trap LiPSs. Meanwhile, the MgCo-LDH shell exposes enough sulfur-philic sites for enhancing chemisorption and catalyzes LiPSs conversion. As a result, when MgCo-LDH/ZIF-67 is used as sulfur host in the cathode, the cell achieves a high discharge capacity of 1121 mAh gat 0.2 C, and an areal capacity of 5.0 mAh cmunder high sulfur loading of 5.8 mg cm. The S/MgCo-LDH/ZIF-67 electrode holds a promising potential for the development of Li-S batteries.
开发高效的硫主体材料以解决多硫化锂（LiPSs）的穿梭效应问题对于锂硫（Li-S）电池至关重要，但仍具有挑战性。在本研究中，设计了一种新型的蛋黄壳结构MgCo-LDH/ZIF-67复合材料作为锂硫电池的正极。在这种复合材料中，壳层是通过Mg对ZIF-67纳米颗粒进行部分蚀刻而构建的MgCo层状双氢氧化物，核心是未反应的ZIF-67颗粒。独特的蛋黄壳结构不仅为硫的容纳提供了丰富的孔隙，还促进了电解质的渗透和离子传输。ZIF-67核心通过路易斯酸碱相互作用对LiPSs表现出强烈的极性吸附，并且微孔/介孔可以进一步捕获LiPSs。同时，MgCo-LDH壳层暴露了足够的亲硫位点以增强化学吸附并催化LiPSs的转化。结果，当MgCo-LDH/ZIF-67用作正极中的硫主体时，电池在0.2 C下实现了1121 mAh g的高放电容量，并且在5.8 mg cm的高硫负载下面积容量为5.0 mAh cm。S/MgCo-LDH/ZIF-67电极在锂硫电池的发展中具有广阔的前景。
