Thermal runaway of electric vehicles: The re-ignition phenomena

Details

Supervisors

Jeanmart, Hervé

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en génie de l'énergie , à finalité spécialisée

Abstract

enWith the growing adoption of electric vehicles (EVs), safety concerns related to lithium-ion batteries are becoming increasingly critical, particularly due to the risk of thermal runaway. This master’s thesis presents a comprehensive analysis of thermal runaway phenomena in EV batteries, focusing on their causes, triggering mechanisms, and mitigation strategies. One widely used mitigation approach, immersing the vehicle in a large tank of water, is studied in detail. The objective is to understand why, in some cases, thermal runaway re-ignites after prolonged immersion. A review of the literature reveals several factors that could contribute to reignition, such as a reduction in the ignition temperature of exothermic reactions following water exposure, or localized increases in water conductivity that may intensify short circuits. Building on these insights, the second part of this thesis introduces a 0D thermal model designed to simulate battery behavior under immersion conditions. The model incorporates key effects observed in the literature, including water intrusion, conductivity variations, and ambient temperature. Simulation results demonstrate that water-induced short circuits can initiate thermal runaway and that several parameters critically influence the likelihood of re-ignition, most notably water penetration into the battery, local water conductivity near the cells, and surrounding air temperature. These findings provide valuable insights into the root causes of post-immersion reignition and suggest potential pathways for its prevention. Ultimately, this research aims to support the development of safer firefighting strategies and reduce the risks associated with EV battery fires.