Flexible 2D Boron Imidazolate Framework for Polysulfide Adsorption in Lithium–Sulfur Batteries
Flexible 2D Boron Imidazolate Framework for Polysulfide Adsorption in Lithium–Sulfur Batteries
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DOI：
10.1021/acs.chemmater.2c02324
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发表时间：
2022-11
影响因子：
8.6
通讯作者：
Soumyodip Banerjee;Xu Han;M. Siegler;E. Miller;N. Bedford;Brandon C. Bukowski;V. S. Thoi
中科院分区：
文献类型：
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作者：
Soumyodip Banerjee;Xu Han;M. Siegler;E. Miller;N. Bedford;Brandon C. Bukowski;V. S. Thoi
“多硫化物穿梭”是由多硫化物溶解引发的过程，被认为是锂硫（Li-S）电池的主要失效机制之一。许多研究工作致力于有效的阴极添加剂和主体材料，以抑制多硫化物物质的浸出。在此，我们报告了一个新的二维金属有机框架构成的三位配体，硼咪唑（[BH（Im）3]-，Im =咪唑），和钴离子的多硫化锂吸附。咪唑钴骨架（CoN 6-BIF）含有八面体配位的Co中心，在a，b平面上形成二维层。与硫/碳对照相比，含有CoN 6-BIF的复合阴极表现出高的硫利用率和容量保持率，从而提高了比容量和循环寿命。密度泛函理论（DFT）计算表明，CoN 6-BIF连接体是旋转柔性的，允许框架在膨胀的孔中容纳多硫化物。BIFs的这种不寻常的性质为探索柔性金属有机框架（MOFs）及其在储能方面的应用开辟了新的途径。
The “polysulfide shuttle,” a process initiated by the dissolution of polysulfides, is recognized to be one of the major failure mechanisms of lithium–sulfur (Li–S) batteries. Much research effort has been dedicated toward efficient cathode additives and host materials to suppress the leaching of polysulfide species. Herein, we report a new 2D metal–organic framework constituted by a tritopic ligand, boron imidazolate ([BH(Im)3]−, Im = imidazole), and Co2+ions for lithium polysulfide adsorption. The cobalt imidazolate framework (CoN6-BIF) contains octahedrally coordinated Co centers that form two-dimensional layers in thea,bplane. Composite cathodes containing CoN6-BIF exhibited high sulfur utilization and capacity retention, resulting in improved specific capacity and cycle life compared to sulfur/carbon controls. Density functional theory (DFT) calculations suggest that CoN6-BIF linkers are rotationally flexible, allowing the framework to accommodate polysulfide in the expanded pores. This unusual property of BIFs opens up new avenues for exploring flexible metal–organic frameworks (MOFs) and their applications to energy storage.