Extended Physics-Based Reduced-Order Capacity Fade Model for Lithium-Ion Battery Cells1

Aging models are necessary to accurately predict the state of health (SOH) evolution in lithium-ion battery systems when performing durability studies under realistic operations, specifically considering time-varying storage, cycling, and environmental conditions, while being computationally efficient. This article extends existing physics-based reduced-order capacity fade models that predict degradation resulting from the solid electrolyte interface (SEI) layer growth and loss of active material (LAM) in the graphite anode. Specifically, the physics of the degradation mechanisms and aging campaigns for various cell chemistries are reviewed to improve the model fidelity. In addition, a new calibration procedure is established relying solely on capacity fade data and results are presented including extrapolation/validation for multiple chemistries. Finally, a condition is integrated to predict the onset of lithium plating. This allows the complete cell model to predict the incremental degradation under various operating conditions, including fast charging.