Characterizing the Microstructure of Separators in Lithium Batteries and Their Effects on Dendritic Growth
Characterizing the Microstructure of Separators in Lithium Batteries and Their Effects on Dendritic Growth
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DOI：
10.1021/acsaem.1c00144
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发表时间：
2021-08
影响因子：
6.4
通讯作者：
Andrew Cannon;E. Ryan
中科院分区：
文献类型：
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作者：
Andrew Cannon;E. Ryan
多孔隔膜用于物理分离电池中的电极，同时提供机械稳定性并改善锂电池的性能。在这项研究中，电池隔膜的微观结构的质量传输和锂枝晶生长的影响进行了研究，使用孔隙尺度的计算建模。隔膜的微观结构特征，例如孔隙率、弯曲度和收缩性，直接改变电池循环期间锂离子的扩散路径。实验关系的准确性，即，Bruggeman，MacMullin，用来确定这些特征是不可靠的。一个孔隙尺度的计算模型被用来模拟质量传输和枝晶生长，利用一个明确的表示的分离器的微观结构。模拟相比，实验关系，并表明，实验关系未能充分捕捉重要的物理特性的微观结构的分离器。弯曲度，一个特性，这是很难实验测量，显着影响枝晶的生长速度，并可能导致电池寿命较短。此外，在电池隔板的异质性的程度进行了探讨，并显示，导致不同的枝晶生长速率，即使当隔板的本体物理特性是相同的。本文提供的证据表明，忽略这些属性的局部变化可能导致不均匀的扩散，反过来，有问题的枝晶生长。这些发现提供了对电池隔板设计中不常考虑的特性的深入了解。
Porous separators are used to physically separate the electrodes in batteries while providing mechanical stability and improving the performance of lithium batteries. In this study, the effect of the battery separator microstructure on mass transport and lithium dendrite growth is investigated using pore-scale computational modeling. The microstructural characteristics of the separator, such as porosity, tortuosity, and constrictivity, directly alter diffusion paths for lithium ions during battery cycling. The accuracies of experimental relations, i.e., Bruggeman, MacMullin, used to determine these characteristics are unreliable. A pore-scale computational model is used to simulate mass transport and dendrite growth, utilizing an explicit representation of the separator microstructure. The simulation is compared to the experimental relations and shows that the experimental relations fail to adequately capture important physical characteristics in the microstructure of the separator. Tortuosity, a characteristic that is difficult to experimentally measure, is shown to significantly affect the growth rate of dendrites and can lead to a shorter lifetime in the battery. Additionally, the degree of heterogeneity in a battery separator is explored and shown to lead to different dendrite growth rates even when the bulk physical characteristics of separators are the same. Evidence provided in this paper suggests that neglecting local variation of these properties can lead to nonuniform diffusion and, in turn, problematic dendritic growth. The findings offer insight into properties not often considered in battery separator designs.