Master thesis and internship[BR]- Master's thesis : Numerical analysis of a passively air-cooled lithium-ion pouch cell battery case under different discharge rates[BR]- Integration internship

Abstract

Thermal management is a critical aspect of lithium-ion cells as it directly affects their performance and safety, particularly in unmanned aerial vehicles where compact and lightweight solutions are essential. This thesis is divided into two parts. The first part focuses on the thermal behaviour of a battery pack under different discharge rates. A numerical model was developed and validated using experimental data from a single-cell discharge test. The final design featured stamped aluminium cooling plates and was able to maintain the cell temperatures within the safe operating limits at 0.5C, 1C and 1.5C discharge rates for the entire discharge cycle. The safe discharge limits of the battery pack could then be defined. The second part of focused on finding a suitable thermal barrier material to prevent cell-to-cell propagation of thermal runaway. Heat abuse experiments were carried out and the silica aerogel-based Skogar® HT (3 mm) provided the best insulation performance, significantly limiting back surface temperature rise. This thesis highlights the importance of surface area and thermal conductivity in passive air-cooled systems as well as the importance of using experimental data to improve and validate numerical models to ensure accurate results. This thesis shared insights into how the safety of battery packs could be improved by considering the effects of thermal runaway and how to prevent or mitigate its spread.