High-Fidelity Modeling of Lithium-Ion Batteries Integrating Electrochemical-Thermal Dynamics and Solid-Electrolyte-Interface-Driven Capacity Degradation

Abstract This paper introduces a novel multiphysics modeling approach for lithium-ion batteries that explicitly couples electrochemical-reactions, thermal-dynamics, and capacity-degradation mechanisms. Using explicit equations that are highly suitable for practical applications, the model combines a one-dimensional electrochemical model with a three-dimensional thermal model. This framework effectively incorporates SEI (Solid-Electrolyte Interphase) layer formation and growth on graphite particles, establishing a direct and mechanistic link to capacity degradation. The model simulates essential internal features, including Li-ion concentration distribution, thermal gradients, and SEI growth dynamics. Simulation results demonstrate consistent and robust performance across a wide range of discharge rates (1C to 3C) and ambient temperatures (15°C to 35°C), validating the model's reliability under diverse operating conditions. Validation against experimental data from Sandia National Laboratories demonstrates high accuracy: maximum capacity degradation error < 2%, discharge time error < 166 s (simulation 8607.27s vs experimental 8773.17s), and temperature variations < 2.5%. These outcomes confirm the model's effectiveness in capturing capacity fade, temperature evolution, and charge/discharge voltage behavior. Overall, by explicitly modeling the coupling among electrochemistry, heat transfer, and SEI-related capacity loss within a practical P2D framework, this approach provides a highly efficient and predictive tool for battery performance (battery voltage, thermal behavior, and capacity degradation) analysis.