Xiao Jiewen; Zhou Guangmin; Chen Hetian; Feng Xiang; Legut Dominik; Fan Yanchen; Wang Tianshuai; Cui Yi; Zhang Qianfan. Elaboration of Aggregated Polysulfide Phases: From Molecules to Large Clusters and Solid Phases. Nano Letters. 2019, vol. 19, issue 10, s. 7487-7493. ISSN 1530-6984, eISSN 1530-6992, DOI: https://doi.org/10.1021/acs.nanolett.9b03297.
The article published in Nano Lett. 2019, 19, 7487-7493 is a comprehensive study of the solid-state lithium polysulfide intermediates in the lithium-sulphur battery. The lithium−sulphur (Li−S) battery, based on the multistep reactions between the lithium metal and sulphur, has emerged as one of the most promising candidates due to its high specific energy density. However, the practical application is still hampered by several obstacles, especially for the shuttle problems (formation of Li-S compounds leaking into electrolyte moving between anode and cathode). Therefore, there are increasing strategies aiming at this problem to significantly reduce dissolved polysulfides. However, except for the solid-state Li2S2 and Li2S, other aggregated phases of polysulfides remain unexplored, especially in well-confined cathode material systems. Therefore, from this perspective, our work reports a series of nanosize polysulfide clusters and solid phases appearing from an atomic perspective. The phase diagram and formation energy evolution demonstrate their stabilities and cohesive tendency. It is interesting to find that Li2S6 can stay in the solid state and contains short S3 chains structure. Simulated electronic properties show the reduced band gaps when polysulfides are aggregated, especially for the solid phase Li2S6 with a band gap as low as 0.47 eV. Their dissolution behavior and conversion process are also investigated, which provides a more realistic model and gives further suggestions on the future design of the Li-S battery. Furthermore, the completion of this comprehensive work was only possible with the IT4Inovations HPC CPU time resources utilizing the Path to Exascale project.