Numerical Simulation of Cell Venting within a Simplified 18650 Li-Ion Battery Pack

Violation of nominal operating conditions in Li-ion batteries can lead to internal damage and failure of the cells. This usually triggers chemical reactions that produce a large volume of hot gas. As a safety feature, 18650 battery cells are equipped with a safety vent. Once an internal pressure threshold is exceeded, the vent opens, and the gas escapes the cell at a high velocity to prevent uncontrolled structural failure. Within a battery pack, the hot gas needs to be guided to exit the pack while at the same time keeping neighbouring battery cells cool enough to stay within the safe temperature range. CFD simulation offers the capabilities to explore the mechanism of battery cell venting and flow guidance. This paper describes how such a simulation can be set up and run. Several steps are necessary to achieve this. First, Simcenter Battery Design Studio is used to model the 18650 battery cells. However, it is also described how this step can be avoided if certain prior knowledge about the process is available. Simcenter STAR-CCM+ is used for that and all subsequent steps. The cells are then assembled to a battery module and placed within a simplified battery pack housing.