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Sulfur crystallization in the cathode of lithium-sulfur battery during the charging process: A possible alternative to reduce the shuttle effect
Materials Today Energy ( IF 9.3 ) Pub Date : 2020-10-24 , DOI: 10.1016/j.mtener.2020.100566
Z. Yang , G. Pan , Y. Hu , J. Zhang

Most studies on lithium-sulfur batteries have paid attention to eliminating the shuttle effect caused by polysulfides via trapping polysulfides in cathodes. However, the charging process is neglected because the formation of an eight-membered sulfur ring is hindered by the low probability of head-to-tail contact in the long eight-membered chain. However, reducing the polysulfide concentration in an electrolyte can also be a good alternative. In this study, benefiting from electrolyte additives, polysulfide concentration in the electrolyte is reduced by oxidizing soluble polysulfides into insoluble sulfur disposing on surface of graphene during charging. Furthermore, high-resolution transmission electron microscopy images of the cathode charged to 3.0 V show that this sulfur crystal transforms from rectangular to regular hexagonal in a single crystal plane, revealing that the most stable crystal type for sulfur in this system is hexagonal and not rhombic. And reducing the shuttle effect by decreasing the density of polysulfides in the electrolyte via sulfur crystallization during charging is a novel and promising method.



中文翻译:

锂硫电池正极在充电过程中的硫结晶:降低穿梭效应的可能替代方法

关于锂硫电池的大多数研究都集中在通过将多硫化物捕获在阴极中来消除由多硫化物引起的穿梭效应。但是,由于在长的八元链中头尾接触的可能性低,因此阻碍了八元硫环的形成,因此忽略了充电过程。但是,降低电解质中的多硫化物浓度也可以是一个很好的选择。在这项研究中,受益于电解质添加剂,在充电过程中,可溶的多硫化物通过氧化溶解在石墨烯表面的不溶性硫而降低了电解质中的多硫化物浓度。此外,阴极的高分辨率透射电子显微镜图像为3。0 V表明,该硫晶体在单晶平面上从矩形转变为正六边形,这表明该系统中最稳定的硫晶体类型是六边形而不是菱形。通过在充电过程中通过硫结晶降低电解质中多硫化物的密度来降低穿梭效应是一种新颖而有前途的方法。

更新日期:2020-11-21
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