Ab initio structure search and in situ 7Li NMR studies of discharge products in the Li-S battery system
See, Kimberly A
Matthews, Peter D
Van, der Ven Anton
Journal of the American Chemical Society
American Chemical Society
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See, K. A., Leskes, M., Griffin, J., Britto, S., Matthews, P. D., Emly, A., Van, d. V. A., et al. (2014). Ab initio structure search and in situ 7Li NMR studies of discharge products in the Li-S battery system. Journal of the American Chemical Society, 136 16368-16377. https://doi.org/10.1021/ja508982p
The high theoretical gravimetric capacity of the Li–S battery system makes it an attractive candidate for nu-merous energy storage applications. In practice, cell performance is plagued by low practical capacity and poor cycling. In an effort to explore the mechanism of the discharge with the goal of better understanding performance, we examine the Li–S phase diagram using computational techniques, and complement this with an in situ 7Li NMR study of the cell dur-ing discharge. Both the computational and experimental studies are consistent with the suggestion that the only solid product formed in the cell is Li2S, formed soon after cell discharge is initiated. In situ NMR spectroscopy also allows the direct observation of soluble Li+-species during cell discharge; species that are known to be highly detrimental to capacity retention. We suggest that during the first discharge plateau, S is reduced to soluble polysulfide species concurrently with the formation of a solid component (Li2S) which forms near the beginning of the first plateau, in the cell configuration studied here. The NMR data suggests that the second plateau is defined by the reduction of the residual soluble species to solid product (Li2S). A ternary diagram is presented to rationalize the phases observed with NMR during the discharge pathway and provide thermodynamic underpinnings for the shape of the discharge profile as a function of cell composi-tion.
In situ NMR, lithium-sulfur batteries, density-functional theory, ab initio structure search, Li-S binary phase diagram
Fellowship support to KAS from the ConvEne IGERT Program of the National Science Foundation (DGE 0801627) is gratefully acknowledged. AJM acknowledges the support from the Winton Programme for the Physics of Sus-tainability. PDM and DSW thank the UK-EPSRC for financial support. This research made use of the shared experimental facilities of the Materials Research Laboratory (MRL), sup-ported by the MRSEC Program of the NSF under Award No. DMR 1121053. The MRL is a member of the NSF-funded Mate-rials Research Facilities Network (www.mrfn.org). CPG and ML thank the U.S. DOE Office of Vehicle Technologies (Con-tract No. DE-AC02-05CH11231) and the EU ERC (via an Ad-vanced Fellowship to CPG) for funding.
External DOI: https://doi.org/10.1021/ja508982p
This record's URL: https://www.repository.cam.ac.uk/handle/1810/246284
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Licence URL: http://creativecommons.org/licenses/by/2.0/uk/