CFD-Based Thermal Abuse Simulations including Gas Generation and Venting of an 18650 Li-Ion Battery Cell

A high-resolution, 3D, computational fluid dynamics (CFD) model was developed and implemented for simulating the heat and gas generation during thermal runaway failure of an 18650 Li-ion battery cell. The model accounts for volumetric gas generation within the active material of the cell and for gas flow through the jellyroll, into the headspace regions, through the safety vent, and out into the surrounding air space. The simulation captures the key features of the oven test, including: self-heating from decomposition reactions, initial venting (i.e. blowdown), temperature decrease due to evaporative cooling, thermal runaway, a second venting event associated with thermal runaway, and cooldown. The highly detailed geometric model of the safety vent allowed for new insight into the physics of venting during thermal runaway. Secondary flows, including ring vortices, counter-rotating vortex pairs, and corner vortices, were found to increase the rate of mixing of the vented gases with the surrounding air. The simulation was compared to previously reported experimental results and found to have good qualitative agreement of jet flow direction. The present thermal abuse model forms the basis for future studies to consider the role of gas impingement heat transfer and gas combustion in full battery pack propagating failures.