Hickson Darby T, Halat David M, Ho Alec S, Reimer Jeffrey A, Balsara Nitash P
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA.
Phys Chem Chem Phys. 2022 Nov 9;24(43):26591-26599. doi: 10.1039/d2cp02622h.
Improving transport properties of electrolytes is important for developing lithium-ion batteries for future energy storage applications. In Newman's concentrated solution theory, electrolytes are characterized by three transport parameters, conductivity, diffusion coefficient, and transference number, in addition to the thermodynamic factor. In this work, these parameters are all determined for an exemplar liquid electrolyte, lithium bis(trifluoromethanesulfonyl)imide mixed in tetraethylene glycol dimethyl ether, using electrochemical methods. The intrinsic coupling between parameters obtained by electrochemical methods results in large error bars in the transference number that obscure the transport behavior of the electrolyte. Here, we use electrophoretic NMR (eNMR) to measure the electric-field-induced ion and solvent velocities to obtain the transference number directly, which enables determination of the thermodynamic factor with greater certainty. Our work indicates that the combination of eNMR and electrochemical methods provides a robust approach for complete characterization of battery electrolytes.
改善电解质的传输特性对于开发用于未来储能应用的锂离子电池至关重要。在纽曼的浓溶液理论中，除了热力学因素外，电解质还由三个传输参数表征，即电导率、扩散系数和迁移数。在这项工作中，使用电化学方法针对一种典型的液体电解质——双（三氟甲磺酰）亚胺锂混合于四甘醇二甲醚中，确定了这些参数。通过电化学方法获得的参数之间的内在耦合导致迁移数出现较大的误差范围，从而掩盖了电解质的传输行为。在此，我们使用电泳核磁共振（eNMR）来测量电场诱导的离子和溶剂速度，以直接获得迁移数，这使得能够更准确地确定热力学因素。我们的工作表明eNMR和电化学方法的结合为全面表征电池电解质提供了一种可靠的方法。
