A Detailed Finite Element Model of Internal Short Circuit and Venting During Thermal Runaway in a 32650 Lithium-Ion Battery

The frequent accidents of power lithium-ion battery have become the major reason to hinder the development of electric vehicles. In this paper, the thermal runaway process for a 32650 battery is analyzed based on 300°C oven heating experiment in adiabatic rate calorimeter, the rise of temperature, the drop of voltage and the leakage of electrolyte are observed before exploding, which could be used as predictor variables for thermal runaway warning. A large number of smoke releases and diffuses after explosion, which could be utilized as a criterion for determining the explosion. And a lumped chemical reaction kinetics model coupled with three-dimensional heat transfer model is constructed for further discussion. The thermal runaway process of the battery could be accurately calculated by the coupled model. Thermal radiation plays a more important role in heat transfer than heat convection in the process of thermal runaway. The explosion happens when the temperature achieves around 230°C, and the active material mainly starts to decompose at this moment.