Heterogeneity of MacMullin number within battery electrodes is a key metric affecting cell performance. To characterize this heterogeneity, an aperture probe was developed. This probe, coupled with a newly developed transmission-line model, allows for measurements of tortuosity, represented by the MacMullin number, on millimeter length scales. Local MacMullin number values of seven electrodes were measured, and the ionic resistance profiles of these electrodes are given through contour maps of the MacMullin number. The method is validated by comparing the average MacMullin number to the value obtained through other measurement methods. The results show significant local MacMullin number variation in such electrodes on a millimeter length scale. This method will allow battery manufacturers and researchers to better quantify sources of heterogeneity and improve electrode quality.
Due to physical effects that happen during fabrication of lithium-ion battery electrodes, the microstructure of the porous electrodes is not uniform. Such heterogeneity has been associated with several battery application issues. For example, variability in transport of ions can lead to a tendency for localized plating of lithium on anodes during fast charging and can contribute to other failure modes [1].There are several approaches to represent heterogeneity. Our research focuses on heterogeneity on a millimeter scale in terms of ionic transport. In a previous presentation, we introduced a technique to measure the local ionic impedance of electrodes [2]. In this report, we provide an update on the development of this technique and display several MacMullin number maps (e.g. Figure 1) to illustrate the heterogeneity of both anodes and cathodes. MacMullin number is a dimensionless ionic resistance related to the tortuosity.On average, the ionic resistivity and the electronic resistivity show different correlations with the porosity [3-4]. MacMullin number maps will be compared to electronic resistivity maps for the same electrodes to evaluate a local correlation between the ionic resistivity and the electronic resistivity. Further, we will evaluate the effect of these heterogeneities on cell performance.[1] Forouzan et al., Journal of The Electrochemical Society 165.10 (2018): A2127.[2] Liu et al., 2019 Meet. Abstr. MA 2019-02 255.[3] Landesfeind et al., Journal of The Electrochemical Society 163.7 (2016).[4] Peterson et al., Journal of The Electrochemical Society 161.14 (2014): A2175. Figure 1
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.