Thermal modeling and simulation of electric vehicle batteries

In this thesis, the thermal behavior of a prismatic lithium-ion battery cell with dimensions of 110 × 50 × 15 mm was analyzed through numerical simulations based on the Joule heat component of the NTGK (Newman-Tiedemann-Gu-Kim) model. The entropic heat term was neglected, and only Joule heat generation was considered. The heat generated during battery operation plays a critical role in ensuring both performance and safety. In particular, under high C-rate discharges, internal temperature gradients significantly increase the risk of thermal runaway and shorten the cell lifespan. In this study, the entropic heat term was excluded; heat generation was evaluated solely via Joule losses. A three-dimensional thermal simulation model was developed using ANSYS Fluent software. The cell was modeled in two regions: the active material and the aluminum casing. Internal heat generation was calculated according to the Joule contribution of the NTGK model. Four discharge scenarios—0.5 C, 1 C, 2 C, and the WLTC driving cycle—were simulated, and the reliability of the results was validated through mesh independence tests and energy balance checks. Simulation results showed a clear rise in maximum temperature with increasing discharge rates. Under the 2 C scenario, the peak temperature reached approximately 47.6 °C, while it remained around 39.1 °C at 1 C. Under the WLTC profile, the maximum temperature was obtained as 35.2 °C, with dynamics differing from those observed in constant-current scenarios. These findings indicate that the NTGK-based numerical approach provides fast and reliable results for the thermal analysis of prismatic cells and offers a solid foundation for engineering applications and the design of thermal management strategies.