The major trend toward vehicle electrification intensifies the need for increased battery energy densities. During the development of new electric vehicle battery technologies, it has become clear that thermal, mechanical, and electrochemical coupling effects play an important role in battery performance, degradation, and response to abusive conditions. The macro-homogeneous Dualfoil model, which solves ion transport and charge transfer dynamics, predicts the electrical response of a single small battery cell. However, when considering large cells or assembled battery modules and packs, inhomogeneity of electric potential and temperature throughout the cell volume becomes severe enough to impact battery performance. Cell expansion and contraction during charge/discharge cycles further increase such inhomogeneity, and the resulting potential and temperature imbalances cause non-uniform current distribution in the cell. Heavily cycled cell regions generate additional heat and stress, causing severe degradation in the performance and life of the battery. Given the strong coupling between thermal, mechanical, and electrochemical phenomena, it is imperative to integrate multiple physical models in the simulation of complete battery packs.

In this work, a modified Dualfoil electrochemical model is coupled to a thermo-mechanical finite element solver to represent such multiphysics coupling effects. Outputs from the 3D thermo-mechanical solver, such as temperature and stress, are supplied as inputs to the Dualfoil model, which in return computes the electrochemical response and provides the local heat generation rate and Li intercalation induced volume change to the thermo-mechanical solver. Using this coupled multiphysics simulation framework, the impact of external mechanical loading under different charge/discharge profiles was investigated. The transient, non-linear behavior of internal variables, such as SOC, overpotential, and current density, during and after cycles, was obtained in the entire 3D battery pack domain. This information provides good insights for design and optimization of battery packs with high performance and long life time.