Automotive battery manufacturers are improving individual cell and overall battery pack design by focusing on increasing 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. Battery pack engineers mitigate the effects of volume change using a variety of methods, though, these mitigation strategies rely on extensive testing with anytime a change in chemistry or pack design is made. Therefore, it is critical to understand the link between active material volume change and the effect on multiple scales.

In this work, we add to a previously developed mechano-electrochemical model to more practically understand the impact of irreversible active material volume change, primarily assigned to SEI layer growth. Initially, a representative volume element model was incorporated into the model geometry to more realistically understand how cell components mechanically interact with each other. This allows for a better understanding of how individual components, including foam added to mitigate volume change, and the overall cell reacts to the active material volume change at the anode electrode during lithiation to generate realistic predictions of pressure and porosity changes. Second, the volume change tied to structural changes for graphite was tied to cell level volume change. Then, a mechano-electrochemical measurement apparatus was developed and used to verify simulation results. This work improves on past efforts and considers the impact of aging on volume change at the particle level, and extends the growth as an irreversible source term to impact the overall cell expansion.

References

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