Experimental and theoretical investigations of heat generation rates for a water cooled LiFePO4 battery

Abstract

Understanding the rate of heat generation in a lithium-ion cell is critical for its safety and performance behavior. This paper presents in situ measurements of the heat generation rate for a prismatic Lithium-ion battery at 1C, 2C, 3C and 4C discharge rates and 5°C, 15°C, 25°C, and 35°C boundary conditions (BCs). For this work, an aluminum-laminated battery consisting of LiFePO4 cathode material with 20Ah capacity was adopted to investigate the variation of the rate of heat generation as a function of the discharge capacity. Ten thermocouples and three heat flux sensors were applied to the battery surface at distributed locations. The results of this study show that the highest rate of heat generation was found to be 91W for 4C discharge rate and 5°C BC while the minimum value was 13W measured at 1C discharge rate and 35°C BC. It was also found that the increase in discharge rate and thus the discharge current caused consistent increase in the heat generation rate for equal depth of discharge points. A model is later developed using the neural network approach and validated. The heat generation rate predicted by the model demonstrates an identical behavior with experimental results.