Thermal modeling and cooling analysis of high-power lithium ion cells

Abstract

The heat generation model and three-dimensional computational fluid dynamics model for lithium ion cells were established with boundary conditions defined. In order to provide a better insight about the behaviors of high-power lithium ion cells under realistic discharge conditions, the temperature difference of the cells and an active thermal management system with a pure air-cooling mode were analyzed and predicted with the factors affecting the unevenness of temperature field discussed. The results show a significant effect of the cooling flow rate on the temperature rise of the cells for all discharge rates. Average surface temperatures are relatively uniform at lower discharge rate that makes it easier to control the temperature of the pack. Cell temperatures are expected to rise significantly toward the end of discharge and they show non-uniformity at higher discharge rates. Adequate air flow rate of active cooling is required at high discharge rate and high ambient temperature for practical pack thermal management system.