Developments in Mechano-Electrochemical Modeling Methods for Battery Electric Vehicles

Abstract

Automotive battery manufacturers are improving individual cell and overall battery pack design by focusing on increasing their performance, durability, and range while reducing cost. However, the coupled mechano-electrochemical phenomena caused by lithiation-based active material volume change significantly complicates the adoption and design of advanced battery systems, especially those with a high degree of volume change, such as silicon. Battery pack engineers mitigate the effects of volume change using a variety of methods, though, these mitigation strategies rely on extensive testing with each change in chemistry or pack design due to the complexity in measuring and understanding the links between active material volume change’s effects on multiple scales.In this presentation, improvements to a previously developed mechano-electrochemical model(1-3) were made to more practically understand impacts of active material volume change. First, a representative volume element model was incorporated into the model geometry to more realistically understand how cell components mechanically interact with each other.(4) This allowed for a better understanding of how individual components, including foam inserts, and the overall cell reacts to the active material volume change of a silicon-graphite electrode upon charge to generate realistic predictions of pressure and porosity changes. Second, the thermodynamically non-ideal active material volume change was accounted for to account for the non-linear volume change of silicon and graphite active materials.(5) A mechano-electrochemical measurement apparatus was developed and used to compare results with simulation. Further discussion will be provided on concepts important to the automotive industry, such as the mechanical effects of N:P capacity ratio, porosity limitations for different cell types, etc.References T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3592 (2017).T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3552 (2017).T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, Journal of The Electrochemical Society, 161, E3297 (2014).D. J. Pereira, J. W. Weidner and T. R. Garrick, Journal of The Electrochemical Society, 166, A1251 (2019).D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner, and T. R. Garrick, Journal of The Electrochemical Society, 167, 080515 (2020).