Modeling and Analysis of Heat Generation Rate of a Large Format Pouch-Type Lithium-Ion Battery Considering Degradation

The optimal design of a thermal management system is the most crucial factor that requires accurate knowledge of heat generated from the battery during its lifetime. Accordingly, the system design and control should consider the increased heat over the useful life. In this paper, an accurate thermal model considering degradation is developed based on an electrochemical model. The detailed heat sources are determined using internal variables of the electrochemical model and relevant model parameters are updated as the cycling continues and degradation takes place. The model is experimentally validated using a newly developed calorimeter that can accurately control the temperature and measure the heat generation rate of the battery. The validation results have shown that the model can accurately predict both voltage and heat generation rate over the lifetime of the battery up to 25% of capacity fade. Further analysis using the validated model has been conducted to compare the effect of degradation-related parameters on the heat generation, which reveals that the most dominant parameters affecting the heat generation are volume fraction of electrolyte, contact resistance, and capacity. In addition, a breakdown analysis enables to study change of the detailed heat source terms as a function of cycle number.