The formation of passivating films is a common aging phenomenon, for example in weathering of rocks, silicon, and metals. In many cases, a dual-layer structure with a dense inner and a porous outer layer emerges. However, the origin of this dual-layer growth is so far not fully understood. In this work, a continuum model is developed, which describes the morphology evolution of the solid-electrolyte interphase (SEI) in lithium-ion batteries. Transport through the SEI and a growth reaction governed by the SEI surface energies are modelled. In agreement with experiments, this theory predicts that SEI grows initially as a dense film and subsequently as a porous layer. This dynamic phase transition is driven by the slowing down of electron transport as the film thickens. Thereby, the model offers a universal explanation for the emergence of dual-layer structures in passivating films.

中文翻译：

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致密膜和多孔膜生长之间的过渡：双层 SEI 理论

钝化膜的形成是一种常见的老化现象，例如在岩石、硅和金属的风化中。在许多情况下，会出现具有致密内层和多孔外层的双层结构。然而，到目前为止，这种双层生长的起源还没有完全清楚。在这项工作中，开发了一个连续模型，该模型描述了锂离子电池中固体电解质界面 (SEI) 的形态演变。模拟了通过 SEI 的传输和受 SEI 表面能控制的生长反应。与实验一致，该理论预测 SEI 最初生长为致密膜，随后生长为多孔层。这种动态相变是由薄膜变厚时电子传输的减慢驱动的。从而，