Accurate characterization of transference numbers in electrolyte systems
Le-Yen Lin, Chia‐Chin Chen
Abstract
Efficient lithium-ion transport is pivotal for the battery advancement, and the transference number plays a central role in achieving this efficiency. In the literature, significant discrepancies in transference number values are often observed. For instance, in polymer electrolytes , notable inconsistencies in transference numbers exist even when the electrolyte chemistry , such as salt concentration and polymer molecular weight , is held constant. Therefore, conventional wisdom focusing on the material chemistry cannot explain these inconsistent results. Herein, we report a long-standing overlooked aspect: the discrepant transference number results can stem from the misestimation of parameters in measurement methodologies. Our analysis leverages the transmission-line-model applied to a polyethylene oxide electrolyte, allowing us to reevaluate traditional measurement methods. Through this reassessment, we not only uncover how the determination of measurement parameters can exert a significant influence on the attained transference number but also suggest a method to accurately characterize the transference number. Furthermore, we explore the origins of anomalous transference number and elucidate the impact of transference number on electrochemical impedance and direct-current polarization experiments. This research contributes vital insights into addressing critical challenges associated with transference number measurements in electrolyte systems, promoting the development of more efficient lithium-ion transport in battery technology.