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DOE OSTI · 1903026

Flexible 2D Boron Imidazolate Framework for Polysulfide Adsorption in Lithium–Sulfur Batteries

Banerjee, Soumyodip·Han, Xu·Siegler, Maxime A.·Miller, Elisa M.·Bedford, Nicholas M.·Bukowski, Brandon C.·Thoi, V. Sara
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Abstract

We report 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 Co 2+ ions for lithium polysulfide adsorption. The cobalt imidazolate framework (CoN 6 -BIF) contains octahedrally coordinated Co centers that form two-dimensional layers in the a,b plane. Composite cathodes containing CoN 6 -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 CoN 6 -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.

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25 ENERGY STORAGE2D metal-organic frameworkcathode additiveslithium-sulfur batteriessolar-photochemistry

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Banerjee, Soumyodip, Han, Xu, Siegler, Maxime A., Miller, Elisa M., Bedford, Nicholas M., Bukowski, Brandon C., Thoi, V. Sara. 2022-11-15. Flexible 2D Boron Imidazolate Framework for Polysulfide Adsorption in Lithium–Sulfur Batteries. https://doi.org/10.1021/acs.chemmater.2c02324

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