Exergy analysis of a lithium-ion battery thermal management system considering lithium plating

Lithium-ion cells are used throughout the automotive industry in EVs. Their performance and lifespan are dependent on their operating temperature; therefore, the temperature must be maintained during their operation using a battery thermal management system. In this paper a numerical investigation of a small battery pack consisting of three series connected 20 Ah LiFePO 4 cells separated by cooling plates is analyzed with the goal of finding the conditions that reduce the exergy destruction and likelihood of lithium plating experienced during charging. COMSOL Multiphysics® v6.2 was used to subject the pack to a constant current-constant voltage charging cycle at rates of 1C, 2C, 3C, and 4C while the inlet temperature of the coolant was set to 10 °C, 20 °C, 30 °C, and 40 °C. The exergy destruction and likelihood of lithium plating of each case were analyzed. It was found that in order to reduce both the exergy destruction and likelihood of lithium plating, the charging rate should be reduced as much as possible, and the difference between the coolant temperature and surroundings should be reduced while maintaining a temperature between 20 and 25 °C. These findings can be useful when developing thermal management systems and charging algorithms to improve their performance and increase the cell's lifespan.