Time efficient simulations for advanced battery cooling concepts enabling EV fast charging

Abstract

The transition to electric vehicles (EVs) requires advancements in battery technology to improve range and minimize charging times. Fast charging is a key feature to enable the widespread adoption of EVs, but it presents significant thermal management challenges due to the thermal instability and higher degradation of Li-ion batteries. To address this issue, advanced battery cooling concepts are required to ensure their safety and longer lifespan. This thesis presents a method to simulate the 3D thermal behaviour of a battery module under fast charging with a given cooling strategy. This includes accurate modelling of cells to couple their electrical behaviour with thermal behaviour while considering the ohmic heating in busbars and the contribution of the cooling system. The simulation is set up in StarCCM++ using the BatterySim® tool for cell modelling. The case-study simulations are carried out on a standard battery pack with a cooling plate at the battery module’s bottom. The method is verified by performing a real-time fast charging test that showed that the simulation results are in good agreement with the test data. With a 20 minutes fast charging strategy, the simulation results indicate that this cooling approach leads to a higher temperature on the top surface of the cells. Hence, the design is modified by adding another cooling plate to the top. This design effectively cools the battery with minimal temperature gradients. Another studied strategy, involving the placement of thin heat pipes between each cell, proved to be an even more effective approach as cells were cooled efficiently and uniformly. By using this method, the design of a battery module can be further optimized to have a more uniform temperature in the optimum temperature range.