Prehal, Christian; Talian, Sara Drvarič; Vizintin, Alen; Amenitsch, Heinz; Dominko, Robert; Freunberger, Stefan AlexanderISTA ; Wood, Vanessa
Insufficient understanding of the mechanism that reversibly converts sulphur into lithium sulphide (Li2S) via soluble polysulphides (PS) hampers the realization of high performance lithium-sulphur cells. Typically Li2S formation is explained by direct electroreduction of a PS to Li2S; however, this is not consistent with the size of the insulating Li2S deposits. Here, we use in situ small and wide angle X-ray scattering (SAXS/WAXS) to track the growth and dissolution of crystalline and amorphous deposits from atomic to sub-micron scales during charge and discharge. Stochastic modelling based on the SAXS data allows quantification of the chemical phase evolution during discharge and charge. We show that Li2S deposits predominantly via disproportionation of transient, solid Li2S2 to form primary Li2S crystallites and solid Li2S4 particles. We further demonstrate that this process happens in reverse during charge. These findings show that the discharge capacity and rate capability in Li-S battery cathodes are therefore limited by mass transport through the increasingly tortuous network of Li2S / Li2S4 / carbon pores rather than electron transport through a passivating surface film.
This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant NanoEvolution, grant agreement No 894042. The authors acknowledge TU Graz for support through the Lead Project LP-03. Likewise, the use of SOMAPP Lab, a core facility supported by the Austrian Federal Ministry of Education, Science and Research, the Graz University 6 of Technology, the University of Graz, and Anton Paar GmbH is acknowledged. S.D.T, A.V. and R.D. acknowledge the financial support by the Slovenian Research Agency (ARRS) research core funding P2-0393. Furthermore, A.V. acknowledge the funding from the Slovenian Research Agency, research project Z2-1863. S.A.F. is indebted to IST Austria for support.
Prehal C, Talian SD, Vizintin A, et al. Mechanism of Li2S formation and dissolution in Lithium-Sulphur batteries. Research Square. doi:10.21203/rs.3.rs-818607/v1
Prehal, C., Talian, S. D., Vizintin, A., Amenitsch, H., Dominko, R., Freunberger, S. A., & Wood, V. (n.d.). Mechanism of Li2S formation and dissolution in Lithium-Sulphur batteries. Research Square. https://doi.org/10.21203/rs.3.rs-818607/v1
Prehal, Christian, Sara Drvarič Talian, Alen Vizintin, Heinz Amenitsch, Robert Dominko, Stefan Alexander Freunberger, and Vanessa Wood. “Mechanism of Li2S Formation and Dissolution in Lithium-Sulphur Batteries.” Research Square, n.d. https://doi.org/10.21203/rs.3.rs-818607/v1.
C. Prehal et al., “Mechanism of Li2S formation and dissolution in Lithium-Sulphur batteries,” Research Square. .
Prehal C, Talian SD, Vizintin A, Amenitsch H, Dominko R, Freunberger SA, Wood V. Mechanism of Li2S formation and dissolution in Lithium-Sulphur batteries. Research Square, 10.21203/rs.3.rs-818607/v1.
Prehal, Christian, et al. “Mechanism of Li2S Formation and Dissolution in Lithium-Sulphur Batteries.” Research Square, doi:10.21203/rs.3.rs-818607/v1.
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