Thermodynamic Optimization of Water-Cooled Infrastructure for Vehicle Lithium-Ion Battery Based on Exergy

Electric vehicle technology is developing rapidly with the attention of energy and environmental issues, lithium-ion batteries as the important component are widely used for their superior performance. However, batteries generate a lot of heat during operation. If not cooled in time, heat will accumulate in the battery package, causing a rapid temperature rise and an increasing temperature nonuniformity. Thermodynamic analysis based on the least exergy dissipation principle is to optimize both the configuration and operating strategy of a water-cooled system for the vehicle lithium-ion battery packages. Four typical structures and 24 packages of 96 lithium-ion single batteries from an e-powered SUV were designed and tested to verify the exergy-based optimization. The test results showed a good agreement with the theoretical analysis and prediction. Under various battery discharging conditions, the best thermal performance was observed when the cooling water was inlet to the middle-positioned battery packages, at which the measured maximum temperature gradient among the 24 battery packages can be controlled within 3.1 K, much lower than the other three configurations, and the measured peak temperature was 1.1-5.9 K lower than the other three configurations.