Numerical Approach for the Characterization of the Venting Process of Cylindrical Cells under Thermal Runaway Conditions

Increasing awareness of the harmful effects on the environment of traditional Internal Combustion Engines (ICE) drives the industry toward cleaner powertrain technologies such as battery-driven Electric Vehicles (EV). 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 made to understand this phenomenon and increase battery safety. Specifically, the vented gases and their ignition can cause the propagation of this phenomenon to adjacent batteries in a pack. In this work, Computational Fluid Dynamics (CFD) is employed to predict this venting process in an LG18650 cylindrical battery. The shape of the venting cap deformation obtained from experimental results was introduced in the computational model. 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 appropriate methodology to set the proper boundary conditions that faithfully recreate these events, including a total pressure-inlet, pressure-outlet configuration. Once achieved, macroscopic characteristics of the jet, including tip penetration and jet angle, have been extracted and compared against results obtained from the Schlieren technique for the initial venting stage (1st 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, resulting in an appropriate methodology for predicting cell venting jets.