Three-Dimensional Thermal Model of a Lithium Ion Battery for Hybrid Mobile Working Machines: Determination of the Model Parameters in a Pouch Cell

Effective heat transfer and protection against high operating temperatures are important, lifetime-affecting items in the design and operation of batteries, especially those intended for hybrid mobile working machines, where the peak power and current demands are high. This paper describes a methodology for the modeling of the electrical and thermal behavior of lithium ion pouch cells for hybrid mobile working machines. The model is produced by coupling the equivalent electrical circuit of the pouch cell and the 3-D pouch cell thermal model. The temperature dependence of the battery operation parameters is added to the model in order to analyze the influence of temperature on heat generation during battery operation. Determination of the parameters of the thermal model is carried out empirically based on the presented methodology, which allows the construction of a 3-D thermal model of a pouch cell without requiring detailed information about the battery chemistry. The validity of the modeling procedure is demonstrated experimentally for a 60 Ah lithium titanate pouch cell.