Mr. Igor BASTOS BEZERRA RÈGO will publicly defend his PhD dissertation entitled “Thermal runaway battery fires: methodology, instrumentation, and validation using intumescent flame-retardant polypropylene composites”.
Supervised by Ms. Gaëlle FONTAINE and Mr. Serge BOURBIGOT.
The defense will take place on Wednesday, September 23, 2026, at 9:30 AM, in the Auditorium of the Institut Chevreuil, Avenue Paul Langevin, Cité Scientifique, 59650 Villeneuve-d’Ascq.
Summary
Electric vehicles (EVs) are increasingly recognized as a viable response to the global warming crisis. However, the Li-ion batteries (LIBs) they rely on present significant safety challenges due to the risk of thermal runaway (TR): an uncontrolled self-heating process triggered by thermal, mechanical, or electrical abuse, resulting in catastrophic failures characterized by intense jet fires, release of toxic gases, and violent ejection of solid particles derived from electrode degradation. Providing passengers with sufficient time to evacuate the vehicle during a TR event, while meeting the weight-reduction demands of the industry, represents a challenge. Polypropylene (PP)-based composites stand out as lightweight alternatives to the steel or aluminum alloys traditionally used in battery enclosures, owing to their low cost, low density, and attractive mechanical properties. Yet their inherent flammability requires the development of advanced flame-retardant strategies. Current research focuses on intumescent flame retardants (IFRs), which protect the polymer substrate by forming an expanded, thermally insulating char layer when exposed to heat. To enhance the efficiency of these systems at lower loadings, researchers are investigating the use of synergists (e.g., boron and silicon-based additives) that reinforce the mechanical integrity and thermal resistance of the char structure in the condensed phase. Despite this potential, the state-of-the-art reveals a lack of standardized methodologies for benchmarking battery enclosure materials. Existing safety protocols fail to replicate the dynamic stresses of a real TR fire. While the UL 2596 standard (first released in 2021) introduced methodologies such as the “Torch and Grit” test to simulate the combined stresses of jet fires and solid ejections, the time-resolved mechanisms of material failure under these conditions remain poorly understood. To address this gap, a novel laboratory-scale fire test bench was developed to reproduce the combined thermal and mechanical stresses experienced by battery enclosure materials during a TR. Non-halogenated IFR systems in glass fiber-reinforced PP composites were formulated and evaluated. Ammonium polyphosphate/melamine and piperazine pyrophosphate/melamine polyphosphate were investigated, coupled with zinc borate and silsesquioxanes (among others) as synergists. The chemical and physical mechanisms governing their barrier performance were characterized in depth. The results demonstrate that the performance of glass fiber-reinforced PP composites against TR-like fires can be substantially improved through IFR incorporation, while particular synergists have a drastic impact on their mechanisms even at low loadings (3 wt%). This work provides both a fully characterized test methodology and material behavior insights to advance the development of lightweight, cost-effective battery enclosure materials without compromising safety.