Thermal runaway is one of the most hazardous safety risks in electric vehicles for both vehicle passengers as well as a vehicle’s surroundings.

The need for numerical modeling of thermal runaway events is mainly due to two reasons:

• the complexity of the physical processes occurring during thermal runaway and the interactions between these processes.
• the difficulty of extracting sufficient information from experimental thermal runaway testing (e.g., obtaining cell internal temperatures, etc.) as well as the costly nature of building enough prototypes to reach a safe design.

For these reasons, it is quite useful to have a numerical modeling framework that can provide enough understanding of the physics behind thermal runaway propagation as well as identify the key factors that affect the propagation within a module as well as within a battery pack.

We have used a methodology where computational fluid dynamics and heat transfer are coupled with an electrochemical model to simulate the following phenomena:

• Heat release from the cells undergoing thermal runaway. The heat release was calculated using electrochemical models describing the sequence of events during a thermal runaway event.
• Propagation of thermal runaway from the initial cell to the neighboring cells
• Propagation of thermal runaway from one module to another

Venting gas and solid ejecta from the cells undergoing thermal runaway.