Characterization of Heat Generation and Its Impact with Cell Aging in a Lithium Ion Cell Using Coupled Electrochemical–Thermal Model

An effective thermal management is crucial for safe battery operation, requiring an accurate prediction of heat generation within the batteries. This work models a Panasonic NCR18650PF cell using a coupled electrochemical with thermal model in COMSOL Multiphysics. Heat generation in the cell and the different components contributing to the total heat were analyzed. The study was done for C-rates from 0.5 to 2, characterizing the domain-wise (cathode, anode, separator) and component-wise (reversible, irreversible) contributions to the total heat generation. Reversible heat was found to dominate at lower current rates, and as the C-rate increased to 2, the irreversible component gained prominence. Electrolyte resistance was found to be the major player in the irreversible component. The total heat generation curve was observed to follow the trend of heat generation contribution from the negative electrode. The study was extended to investigate the effect of cycle aging on cell heat generation by incorporating additional film resistance due to the solid electrolyte interface (SEI) layer growth at the anode. The maximum temperature rise almost doubled at 2000 cycles of operation for the same current rates compared to a new cell.