Investigating the thermal runaway features of lithium-ion batteries using a thermal resistance network model

Abstract

Accurate measurement of the characteristic temperatures of thermal runaway, which are affected by many factors, is important for battery safety evaluation. A one-dimensional thermal resistance network model is built in this study to investigate the influences of various factors on the thermal runaway features of lithium-ion batteries. In the model, the battery is divided into four independent components in the thickness direction, with thermal resistances connecting different nodes. The gas thermal resistance is added to simulate swelling and rupture of the battery. The model can effectively fit the battery thermal runaway behavior under both adiabatic thermal runaway and oven test conditions. Model-based analyses show that the thermal runaway features and characteristic temperatures are significantly affected by the test conditions, thermocouple positions, and battery thickness. The onset temperature of thermal runaway (T2) obtained in the oven test is 48.1 °C lower than that obtained in the adiabatic thermal runaway test. The measured T2 varies at different positions, and the difference can exceed 20% when the battery thickness increases to 10 cm. Moreover, the maximum thermal runaway temperature (T3) at the surface is approximately half that at the other positions. Finally, several suggestions for reasonable thermocouple placement are proposed, which can provide useful guidance for accurately evaluating battery thermal runaway performance.