Experimental Electrothermal Characterization and Modelling of Li-Ion Battery Cells for Automotive Applications

The increasing demand for electric vehicles and energy storage systems relies heavily on the advancement of Li-ion battery technology. Because excessive heat generation can lead to severe performance degradation and safety risks, effective thermal management is one of the primary challenges in battery system design. Thus, accurate electrothermal characterization and modelling are essential for developing precise control strategies and ensuring safe operation. This thesis focuses on the experimental electrothermal characterization and modelling of the Molicel P45B, a 21700 cylindrical Li-ion cell designed for advanced automotive applications. A comprehensive testing methodology was designed and executed using a battery tester, data acquisition system, and thermal chamber. Tests were conducted under both static and dynamic charge and discharge conditions to capture the cell's coupled electrical and thermal responses. Voltage and current measurements were utilized to extract electrical equivalent circuit model parameters, while surface temperature and heat flux were precisely monitored to extract thermal equivalent circuit model parameters, including thermal capacity and entropic heat coefficient. A custom data elaboration script featuring a graphical user interface was developed, significantly reducing the effort required for future characterization work. Finally, a mathematical electrothermal model integrating both the electrical and thermal aspects was implemented in advanced simulation software. The developed model was successfully validated against experimental data, confirming its applicability for realistic scenario simulation. While the study demonstrates the viability of this holistic characterization approach, it also identifies limitations in using hybrid pulse power characterization for equivalent circuit model parameter estimation and notes constraints in first order thermal model accuracy. Ultimately, this work provides a robust foundational framework for electrothermal battery analysis, paving the way for future research into temperature dependent modelling, advanced state of charge estimation, and full integration into the battery management system.