Investigation of the Impact of Flow of Vented Gas on Propagation of Thermal Runaway in a Li-Ion Battery Pack

The venting of hot gases due to rupture of a Li-ion cell during thermal runaway may rapidly transfer thermal energy to neighboring cells in a battery pack and cause propagation of thermal runaway. While thermal runaway has been studied extensively through both measurements and simulations, there is a relative lack of research on the impact of the venting process on thermal runaway propagation. This work presents a non-linear thermal-fluidic simulation of supersonic turbulent flow of hot gases ejecting from a trigger cell and spreading to neighboring cells. Assuming isentropic flow, temperature and speed of the gas flow as functions of time are estimated based on past measurements. These data are used in simulations to determine the thermal impact of the venting process on neighboring cells. The impact of various geometrical parameters of the battery pack on the spreading of venting gases is investigated. Results indicate that cell-to-cell gap, overhead gap and the location of the vent hole on the cell body strongly influence the nature of propagation of thermal runaway to neighboring cells. This work develops a fundamental understanding of an important process during thermal runaway, and may help in the design and optimization of safe Li-ion battery packs for energy conversion and storage.