Department of Materials Science and Engineering, Norwegian University of Science and Technology, NTNU, Trondheim NO-7491, Norway.
J Phys Chem B. 2023 Mar 30;127(12):2729-2738. doi: 10.1021/acs.jpcb.2c08047. Epub 2023 Mar 15.
A systematic description of microscopic mechanisms is necessary to understand mass transport in solid and liquid electrolytes. From Molecular Dynamics (MD) simulations, transport properties can be computed and provide a detailed view of the molecular and ionic motions. In this work, ionic conductivity and transport numbers in electrolyte systems are computed from equilibrium and nonequilibrium MD simulations. Results from the two methods are compared with experimental results, and we discuss the significance of the frame of reference when determining and comparing transport numbers. Two ways of computing ionic conductivity from equilibrium simulations are presented: the Nernst-Einstein approximation or the Onsager coefficients. The Onsager coefficients take ionic correlations into account and are found to be more suitable for concentrated electrolytes. Main features and differences between equilibrium and nonequilibrium simulations are discussed, and some potential anomalies and critical pitfalls of using nonequilibrium molecular dynamics to determine transport properties are highlighted.
为了理解固态和液态电解质中的质量输运，有必要对微观机制进行系统描述。通过分子动力学（MD）模拟，可以计算输运性质，并提供分子和离子运动的详细视图。在这项工作中，从平衡和非平衡 MD 模拟中计算了电解质体系中的离子电导率和迁移数。将这两种方法的结果与实验结果进行了比较，并讨论了在确定和比较迁移数时参考系的重要性。本文提出了两种从平衡模拟中计算离子电导率的方法：能斯特-爱因斯坦近似或昂萨格系数。昂萨格系数考虑了离子相关性，并且更适合于浓缩电解质。讨论了平衡和非平衡模拟之间的主要特点和差异，并强调了使用非平衡分子动力学确定输运性质的一些潜在异常和关键陷阱。
