Lithium-sulfur (Li-S) batteries have recently attracted enormous attention because of high theoretical specific energy (2600 Wh kg-1) and high specific capacity (1672 mAhg-1), as well as the low cost, natural abundance, and nontoxicity of elemental sulfur. They represent one of the most promising candidate technologies for emerging applications in electrical transportation, portable electronics, implanted devices, and communications. However, Li-S batteries often suffer from the dissolving and shuttling of lithium polysulfides (Li2Sx, x =3-8) generated as intermediates during electrochemical conversion of sulfur in the electrolyte. This effect, known as a polysulfide shuttle, could cause capacity fading, poor Coulombic efficiency, and shorten life time, thus hindering the practical realization of Li-S technology. In recent engineering approaches, sulfur and functionalized carbons (graphene, carbon nanotubes, mesoporous hollow carbons, yolk-shell structures) are integrated with polar hosts such as transition metal dichalcogenides, MX2, M = Mo, Ti, X = S, Se) to reduce the effective diffusion length of the polysulfides via anchoring and electrocatalytic transformation of Li2Sx into insoluble Li2S. Consequently, this strategy shows potential to greatly boost the performance and rate capabilities of the Li-S cells . In this work, we report nanoengineered heterostructures composed of thin layers of sulfur, graphene, and MoS2 as diagnostic composite cathodes that could be used for rational design of high- performance Li-S batteries. The morphology, interfaces, crystallinity, and elemental distributions in the cathodes were characterized at multiple scales down to the atomic level using various imaging, diffraction and spectroscopic modes of high-resolution analytical scanning/ transmission electron microscopy (AS/TEM).
Microscopy and Microanalysis, v. 25 (Supplement), Microscopy & Microanalysis 2019 Proceedings
August 4-8, 2019
Microscopy & Microanalysis 2019 Meeting
Sulfur-MoS2-Graphene heterostructure, Li-S battery, analytical scanning/transmission electron microscopy