Understanding the transport properties of the solid electrolyte interphase (SEI) is a critical piece in the development of lithium ion batteries (LIB) with better performance. We studied the lithium ion diffusivity in the main components of the SEI found in LIB with silicon anodes and performed classical molecular dynamics (MD) simulations on lithium fluoride (LiF), lithium oxide (Li₂O) and lithium carbonate (Li₂CO₃) in order to provide insights and to calculate the diffusion coefficients of Li-ions at temperatures in the range of 250 K to 400 K, which is within the LIB operating temperature range. We find a slight increase in the diffusivity as the temperature increases and since diffusion is noticeable at high temperatures, Li-ion diffusion in the range of 1300 K to 1800 K was also studied and the diffusion mechanisms involved in each SEI compound were analyzed. We observed that the predominant mechanisms of Li-ion diffusion included vacancy assisted and knock-off diffusion in LiF, direct exchange in Li₂O, and vacancy and knock-off in Li₂CO₃. Moreover, we also evaluated the effect of applied electric fields in the diffusion of Li-ions at room temperature.

中文翻译：

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锂离子电池中通过固体电解质相间的离子扩散率

了解固态电解质相间（SEI）的传输特性是开发性能更好的锂离子电池（LIB）的关键。我们研究了在具有硅阳极的LIB中发现的SEI的主要成分中锂离子的扩散率，并对氟化锂（LiF），氧化锂（Li ₂ O）和碳酸锂（Li ₂ CO ₃）进行了经典的分子动力学（MD）模拟。），以提供见解并计算锂离子在250 K至400 K范围内（LIB工作温度范围内）的温度下的扩散系数。我们发现随着温度的升高，扩散率略有增加，并且由于在高温下扩散明显，因此还研究了1300 K至1800 K范围内的锂离子扩散，并分析了每种SEI化合物所涉及的扩散机理。我们观察到，锂离子扩散的主要机制包括在LiF中的空位辅助和仿生扩散，在Li ₂ O中的直接交换以及在Li ₂ CO _3中的仿生和仿生。此外，我们还评估了在室温下施加电场对锂离子扩散的影响。