Liang Dongyue, Chen Yuxi, Deng Chuting, de Pablo Juan J
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
ACS Macro Lett. 2024 Oct 15;13(10):1258-1264. doi: 10.1021/acsmacrolett.4c00368. Epub 2024 Sep 13.
Polymer electrolytes are of interest for applications in energy storage. Molecular simulations of ion transport in polymer electrolytes have been widely used to study the conductivity in these materials. Such simulations have generally relied on classical force fields. A peculiar feature of such force fields has been that in the particular case of lithium ions (Li), their charge must be scaled down by approximately 20% to achieve agreement with experimental measurements of ion diffusivity. In this work, we present first-principles calculations that serve to justify the charge-scaling factor and van der Waals interaction parameters for Li diffusion in poly(ethylene glycol) (PEO) with bistriflimide (TFSI) counterions. Our results indicate that a scaling factor of 0.79 provides good agreement with DFT calculations over a relatively wide range of Li concentrations and temperatures, consistent with past reports where that factor was adjusted by trial and error. We also show that such a scaling factor leads to diffusivities that are in quantitative agreement with experimental measurements.
聚合物电解质在能量存储应用中备受关注。聚合物电解质中离子传输的分子模拟已被广泛用于研究这些材料的电导率。此类模拟通常依赖于经典力场。这种力场的一个独特特征是，在锂离子（Li）的特定情况下，其电荷必须缩小约20%，才能与离子扩散率的实验测量结果达成一致。在这项工作中，我们进行了第一性原理计算，以证明在含有双三氟甲磺酰亚胺（TFSI）抗衡离子的聚乙二醇（PEO）中Li扩散的电荷缩放因子和范德华相互作用参数的合理性。我们的结果表明，在相对较宽的Li浓度和温度范围内，0.79的缩放因子与密度泛函理论（DFT）计算结果吻合良好，这与过去通过反复试验调整该因子的报道一致。我们还表明，这样的缩放因子会导致扩散率与实验测量结果在数量上一致。
