Two-way nonlinear mechanical-electrochemical-thermal coupled analysis method to predict thermal runaway of lithium-ion battery cells caused by quasi-static indentation

Recent thermal runaway accidents have caused concerns regarding the safety of lithium-ion batteries (LIBs). Because thermal runaway experiments are dangerous, numerical methods have garnered attention to investigate thermal runaway. Herein, a two-way nonlinear mechanical-electrochemical-thermal coupled analysis method is developed to analyze the internal short-circuit and predict the voltage drop and temperature rise caused by quasi-static indentation. The method is modeled by applying the material nonlinearity of each LIB component and considering detailed layers; then, the internal short-circuit caused by mechanical deformation and cathode-anode contact was calculated. The electrochemical model comprising Randles circuits calculates the heat generated due to internal short-circuit. The thermal model calculates the temperature over time by using heat sources from the electrochemical model. At each timestep, we analyze the internal short-circuit, heat generation, and the temperature rise via mechanical-electrochemical-thermal coupled analysis. The predicted values were compared with the experimental results of spherical-punch indentation using three different diameters for a 3.2 Ah pouch cell; the onset of internal short-circuit and peak temperature varied by 3.3% and 3.2%, respectively, between the predicted values and experimental results. Furthermore, the peak temperature decreased with the increasing diameter of the spherical punch; our model accurately predicts the voltage drop caused by internal short-circuits.