Understanding Battery Degradation and Failure With Impedance and Imaging Techniques

• Main Author: Gober, Megan F
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2024
• Subjects: Electrical engineering; Energy; Materials science
• ISBN: 9798384078159

With the increasing desire for fast charging capabilities in lithium-ion batteries due to the popularity of electric vehicles, research has recently been focused on increasing energy and power density while simultaneously revealing the need for improved understanding of degradation mechanisms to achieve the desired safety and fast charge performance. The work presented seeks to further understanding of mechanical, temperature, and electrochemical degradation mechanisms within varying battery chemistries and geometries through evaluation of impedance response and multiscale imaging techniques. First, in order to understand the limitations of mechanical and electrical integrity of battery systems, a combined application of impedance characterization and X-ray imaging yields a viable approach to establishing an understanding of interactions between mechanics and impedance changes within multiple battery geometries. Second, a connection between morphological and chemical changes within electrode microstructure due to charge cut-off voltage and operating temperature was considered. Results elucidated the need for further modification of the electrode to prevent undesired degradation, while maintaining overall cell capacity. Lastly, to advance the knowledge of the multifaceted relationship between microstructure, macrostructure, and observed electrochemical behavior, a deeper understanding of transport mechanisms within thick electrodes is developed. Results show a clear correlation between lithium transport behavior and anode microstructure, bridging the gap between microstructural observation and electrochemical behavior. Through the above mentioned experimental results, a clear relationship between degradation mechanisms, changing battery impedance, and electrode microstructure is illustrated. Novel multiscale techniques combining electrochemical response, X-ray imaging, and neutron imaging are used to complement commonly used techniques and to develop a deeper understanding of observed degradation mechanisms.