Thermal Behavior of an Intelligent Li-Ion Cell under Vehicle Conditions

Intelligent battery cells follow the approach of having greater knowledge of the single cell state in a battery system by sensors on cell level. The further-reaching approach of reconfigurable battery systems pursues the principle of controlling each cell in a system independently by switches to maximize power and safety of the whole battery system. In the literature, different approaches for sensing, communication and battery management functionality are proposed. However, less attention has been paid to the power loss of such intelligent cells and the resulting thermal effects. Especially for large prismatic cells in an automotive application the temperature is important for power, safety and life-time. Therefore, in this work, an intelligent cell prototype is realized based on a prismatic 25 Ah Li-ion cell. In addition, a 3D thermal model of the intelligent cell is developed and validated experimentally. The model is used to investigate the thermal behavior of an intelligent cell under automotive conditions in detail. The results reveal that an useful application with an temperature increase in the jelly roll of 3 K is only possible with a reduced power loss of the electronics and a well thought-out design for an intelligent cell.