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Theoretical exploration of the structural evolution of sodium sulfide clusters in Na-S batteries
Applied Surface Science ( IF 6.3 ) Pub Date : 2022-11-30 , DOI: 10.1016/j.apsusc.2022.155906
Pan Xiang , Ziqi Tian , Yanle Li , Yang Gao , Zhiming Wang , Liang Chen

The nanosized sodium sulfide species greatly enhance the performance of Na-S batteries. However, as a typical ionic compound, the diminished stability with decreasing cluster size has been rarely considered. Numerous theoretical works only simulated the Na-S binary system based on quite small sodium sulfide clusters, with no account of the stability of the sub-nanoscale cluster. Here, by using an advanced structure search algorithm, we built a binary phase diagram of the sodium sulfide clusters (NSCs). The commonly studied monomer model with low sulfur concentrations is indeed energetically unfavorable, especially for the final discharge product, the Na2S monomer. Therefore, the aggregation of monomers should take place to form multimers. According to the energy, charge, and geometry, relatively stable clusters with low sulfur concentrations are located, including (Na2S5)2, (Na2S4)2, (Na2S3)3, (Na2S2)4, and (Na2S)6 clusters. Furthermore, these multimers bind more intensely to four typical models of carbon-based substrates. The B-doped carbon material exhibits outstanding affinity to NSCs, which may facilitate overcoming the shuttle effect in applications. This work represents a significant step toward understanding the evolution mechanism of NSCs that may guide the future development of high-performance Na-S batteries.



中文翻译:

Na-S电池中硫化钠团簇结构演化的理论探索

纳米级硫化钠物质极大地提高了 Na-S 电池的性能。然而,作为典型的离子化合物,很少考虑随着簇尺寸减小而降低的稳定性。大量理论著作仅仅模拟了基于极小硫化钠团簇的Na-S二元体系,没有考虑亚纳米团簇的稳定性。在这里,通过使用高级结构搜索算法,我们构建了硫化钠簇 (NSC) 的二元相图。通常研究的低硫浓度单体模型在能量上确实是不利的,特别是对于最终的排放产物 Na 2S单体。因此,应该发生单体的聚集以形成多聚体。根据能量、电荷和几何结构,可以找到相对稳定的低硫团簇,包括(Na 2 S 5 ) 2 , (Na 2 S 4 ) 2 , (Na 2 S 3 ) 3 , (Na 2 S 2 ) 4和 (Na 2 S) 6集群。此外,这些多聚体与四种典型的碳基底物模型结合得更紧密。B 掺杂碳材料对 NSC 具有出色的亲和力,这可能有助于克服应用中的穿梭效应。这项工作代表了理解 NSCs 演化机制的重要一步,这可能会指导高性能 Na-S 电池的未来发展。

更新日期:2022-11-30
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