Numerical Approach for the Characterization of the Venting Process of Cylindrical Cells Under Thermal Runaway Conditions 2024-01-2900

The increasing awareness on the harmful effects on the environment of traditional Internal Combustion Engines (ICE) is driving the industry toward cleaner powertrain technologies such as battery-driven Electric Vehicles. Nonetheless, the high energy density of Li-Ion batteries can cause strong exothermic reactions under certain conditions that can lead to catastrophic results, called Thermal Runaway (TR). Hence, a strong effort is being placed on understanding this phenomena and increase battery safety. Specifically, the vented gases and their ignition can cause the propagation of this phenomenon to adjancent batteries in a pack. In this work, Computational Fluid Dynamics (CFD) are employed to predict this venting process in a LG18650 cylindrical battery. The ejection of the generated gases was considered to analyze its dispersion in the surrounding volume through a Reynolds-Averaged Navier-Stokes (RANS) approach. Initial work has focused on developing an appropiate methodology to set the proper boundary conditions that recreate faithfully these events. Once achieved, macroscopic characteristics of the jet including spray tip penetration and spray angle have been extracted and compared against results obtained from Schlieren technique for the initial venting stage (1st venting) and the TR stage (2nd venting). The numerical procedure shows a good agreement with experimental results in the characteristics analyzed, allowing to overcome the limited field-of-view of Schlieren results by providing a complete representation of the spray morphology.