What is it about?
An electrode in cylindrical or pouch cell batteries contains millions of active particles embedded in a conductive network. Battery performance, such as voltage, capacity, and cyclic efficiency, is a collective response of the particle network. We use optical microscopy to measure the local state of charge of individual particles upon charging and discharging, and determine the scale of heterogeneity.
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Why is it important?
1. We demonstrate optical microscopy as a robust method in experiments to determine the local state of charge. We also theoretically prove the relationship between the optical properties and Li composition in the metal oxide cathode. 2. The scale of heterogeneity links particle properties to macroscopically observable metrics in cells. It tells the minimum size of observations in experiments to statistically represent the cell behavior, and size of a representative volume element in computational modeling. 3. Through numerical modeling, Weibull defect population at the particle interface with the conductive matrix can describe the experimental results.
Perspectives
This work emphasizes the importance of the particle network behavior to represent the cell performance at the large scale.
Kejie Zhao
Purdue University System
Read the Original
This page is a summary of: On the scale of heterogeneity in composite electrodes of batteries, Proceedings of the National Academy of Sciences, October 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2520136122.
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