Lithium-ion batteries are widely used in electrical vehicles due to their high energy density and high discharge current. During the charge and discharge phases, the internal resistance of batteries can generate great amounts of heat. Temperature is a very crucial factor that affects the battery life and safety. The lithiumion batteries’ heat generation and temperature distribution were studied to provide a good reference for designing cooling systems. Furthermore, extreme thermal abusive conditions such as internal short-circuit are also simulated in this project.

This project was conducted at NEVS in collaboration with University West in Trollhättan. The heat generation of battery cells and fault injection were simulated based on experiments and CFD (computational fluid dynamic) method.

A number of tasks had to be done in order to build the battery thermal model. The first issue that had to be resolved was being able to gain sufficient physical parameters of Lithiumion battery and this was accomplished through experiments. Once this had been achieved, the final step was to implement the constructed battery thermal model via CFD. The surface temperature of the battery cells was used to validate the simulation model. Three different discharge tests were performed in the experiment part, the discharge currents were 1C, 2C and 3C respectively. The simulated temperatures were compared with real battery temperatures and they were closely corresponding to each other in temperature. Fault injections of the battery were also simulated to have a view on the battery thermal behaviour under extreme abusive conditions. The battery internal shorting has been simulated with different internal resistance and different cross-section areas.