What is it about?
The uniformity of lithium on an electrode is an important factor for reversible and long lasting cell cycling. Typically after cell cycling, batteries are disassembled and images of the lithium on the electrode are taken. Qualitative descriptions of lithium uniformity and morphology (size/shape) are made but this method lacks consistency between research groups and is under-utilizing the power of image analysis. In this work, we propose a quantitative framework to measure lithium uniformity and relate this to battery performance characteristics.
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Why is it important?
We use the index of dispersion as a quantitative metric to measure uniformity which is a unique contribution from otherwise qualitative descriptions. The method we use is simple and open-source. Research groups in the battery community already image their batteries and our tool can be employed as a low hanging fruit for researchers to shift their analysis from a more qualitative to a more quantitative approach making for more robust conclusions and more consistent comparisons across the battery field. Additionally, being able to measure and characterize cycled lithium is an important step on the path to engineering longer lasting lithium metal batteries.
Perspectives
This work approached a simple question - how can we measure something we typically describe with words. Though I found while working on this topic that sometimes the simplest questions can be the hardest to answer. Whenever I would attend battery-related seminars, I felt the importance of this work, as researchers would often use the word "uniform" to describe batteries. It made me think about the subjectivity of these qualitative descriptors and that this work can have a big impact in how we use image analysis techniques more broadly. Ultimately, our society depends on batteries and it has been a pleasure to work towards making longer-lasting and safe batteries.
Jenny Nicolas
University of California San Diego
Read the Original
This page is a summary of: A quantitative imaging framework for lithium morphology: Linking deposition uniformity to cycle stability in lithium metal batteries, Proceedings of the National Academy of Sciences, July 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2502518122.
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