Current imbalance in dissimilar parallel-connected batteries and the fate of degradation convergence

We propose an analytical framework describing how initial capacity and resistance variability in parallel-connected battery cells may inflict additional variability or reduce variability while the cells age. Using this framework, we demonstrate that current imbalance can cause convergent degradation trajectories, consistent with previous reports. However, we also demonstrate that different degradation assumptions, such as those associated with SOC imbalance, may cause divergent degradation. We finally highlight the role of different cell chemistries, including different OCV function nonlinearities, on system behavior, and derive analytical bounds on the SOC imbalance using Lyapunov analysis.

Recommended citation: Weng, A., Movahedi, H., Wong, C., Siegel, J. B., and Stefanopoulou, A. (January 8, 2024). "Current Imbalance in Dissimilar Parallel-Connected Batteries and the Fate of Degradation Convergence." ASME. J. Dyn. Sys., Meas., Control. January 2024; 146(1): 011106. https://doi.org/10.1115/1.4064028
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