Synthesis of Nanomaterials Doped Phase Change Materials for Thermal Management in Li-Ion Batteries and Investigation of the Effect on Thermal Runaway Mechanism

This thesis investigates the synthesis and application of nanomaterials-doped phase change materials (PCMs) as a passive thermal management strategy for lithium-ion batteries, with a particular focus on their ability to mitigate thermal runaway. A dedicated experimental campaign was conducted using nail penetration tests to compare cells with and without PCM encapsulation, while simultaneously monitoring temperature, pressure, and gas composition. Advanced data processing techniques, including interpolation and overlay analysis, were applied to ensure robust interpretation of the results. The findings demonstrate that PCM significantly reduces the severity of thermal runaway. Maximum cell temperature decreased from ~415 °C (no PCM) to ~309 °C (with PCM), while spatial temperature gradients narrowed from ~15 °C to ~5 °C. Pressure peaks were reduced (1.48 bar to 1.25 bar), and gas venting became more controlled. PCM also lowered toxic and flammable emissions by delaying oxygen depletion, reducing CO/CO₂ output, and suppressing NOx formation. Importantly, the presence of PCM altered runaway dynamics: although the onset occurred earlier, the resulting event was much less severe, confirming PCM’s ability to transform catastrophic runaway into a safer process. Mechanistic interpretation attributes these benefits to latent heat buffering, enhanced thermal conductivity from nanomaterial doping, and physical moderation of gas release. Beyond the experimental validation, this thesis contributes an integrated framework for multi-parameter safety analysis, a mechanistic explanation of PCM behaviour, and practical insights for real-world battery pack applications. The work acknowledges limitations related to test scope, single-cell focus, and PCM formulation, and proposes future research directions including module-level studies, hybrid thermal management systems, and machine-learning-based early warning models. Overall, nanomaterials-doped PCM emerges as a promising and scalable safety solution that, when integrated with active cooling and intelligent control, can enable safer and more reliable deployment of lithium-ion batteries in electric vehicles and stationary energy storage.