On the Transport Properties of Li-TFSI Water-in-Salt Electrolytes.
On the Transport Properties of Li-TFSI Water-in-Salt Electrolytes.
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DOI：
10.26434/chemrxiv.9887018.v1
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
Zhujie Li;Roza Bouchal;T. Méndez‐Morales;A. Rollet;Cécile Rizzi;S. le Vot;F. Favier;B. Rotenberg-B.-Rotenb
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作者：
Zhujie Li;Roza Bouchal;T. Méndez‐Morales;A. Rollet;Cécile Rizzi;S. le Vot;F. Favier;B. Rotenberg-B.-Rotenb
盐包水是一种新的电解质，可用于开发水系锂离子电池。它们的结构让人想起离子液体，其特点是离子物质浓度高。在这项工作中，我们通过分子动力学模拟研究了它们的传输特性以及它们如何随浓度变化。我们首先关注力场的选择。通过将模拟粘度和自扩散系数与实验测量结果进行比较，我们选择了一组能够很好地再现传输特性的参数。然后，我们使用选定的力场详细研究所有物种的自扩散率和集体扩散率以及锂离子的传输数的变化。我们表明离子和水之间的相关性在整个浓度范围内发挥着重要作用。在盐包水状态下，阴离子形成渗透网络，降低了阳离子-阴离子相关性，并导致与其他标准电解质相比传输数相当大的值。
Water-in-salts are a new family of electrolytes that may allow the development of aqueous Li-ion batteries. They have a structure which is reminiscent of the one of ionic liquids, and they are characterized by a large concentration of ionic species. In this work we study their transport properties and how they evolve with concentration by using molecular dynamics simulations. We first focus on the choice of the force field. By comparing the simulated viscosities and self diffusion coefficients with experimental measurements, we select a set of parameters that reproduces well the transport properties. We then use the selected force field to study in detail the variations of the self and collective diffusivities of all the species as well as the transport number of the lithium ion. We show that correlation between ions and water play an important role over the whole concentration range. In the water-in-salt regime, the anions form a percolating network which reduces the cation-anion correlations and leads to rather large values for the transport number compared to other standard electrolytes.