Department of Chemistry-Ångström Laboratory, Uppsala University, Lägerhyddsvägen 1, P. O. Box 538, 75121 Uppsala, Sweden.
J Chem Phys. 2023 Apr 28;158(16). doi: 10.1063/5.0146608.
Transference number is a key design parameter for electrolyte materials used in electrochemical energy storage systems. However, the determination of the true transference number from experiments is rather demanding. On the other hand, the Bruce-Vincent method is widely used in the lab to approximately measure transference numbers of polymer electrolytes, which becomes exact in the limit of infinite dilution. Therefore, theoretical formulations to treat the Bruce-Vincent transference number and the true transference number on an equal footing are clearly needed. Here, we show how the Bruce-Vincent transference number for concentrated electrolyte solutions can be derived in terms of the Onsager coefficients, without involving any extrathermodynamic assumptions. By demonstrating it for the case of poly(ethylene oxide)-lithium bis(trifluoromethane)sulfonimide system, this work opens the door to calibrating molecular dynamics (MD) simulations via reproducing the Bruce-Vincent transference number and using MD simulations as a predictive tool for determining the true transference number.
迁移数是电化学储能系统中电解质材料的关键设计参数。然而，从实验中确定真实的迁移数是相当苛刻的。另一方面，Bruce-Vincent 方法广泛应用于实验室中，用于近似测量聚合物电解质的迁移数，在无限稀释的极限下，它变得精确。因此，显然需要理论公式来平等地处理 Bruce-Vincent 迁移数和真实迁移数。在这里，我们展示了如何根据 Onsager 系数推导出浓电解质溶液的 Bruce-Vincent 迁移数，而不涉及任何超热力学假设。通过对聚（氧化乙烯）-双（三氟甲烷磺酰亚胺）锂体系的情况进行演示，这项工作为通过复制 Bruce-Vincent 迁移数并将 MD 模拟用作确定真实迁移数的预测工具来校准分子动力学 (MD) 模拟开辟了道路。
