COMPARISON OF DIFFERENT FLUIDS FOR A HYBRID COOLING STRATEGY OF CYLINDRICAL LITHIUM-ION BATTERIES

This study examines the issue of Lithium-ion battery pack cooling and temperature uniformity. A hybrid cooling strategy is developed that employs air and liquid cooling. A unique design of attaching liquid jackets allows electrically insulating and non-insulating fluids to be used for thermal management strategies. The focus is placed on the typical fluids currently used based on the open literature. These include water, water-glycol (1:1) mix, silicone oil, mineral oil, hydrofluoroether, and poly-alpha-olefin. Moreover, to improve heat extraction through the airflow, turbulence in the battery pack is increased by adding passive airflow devices. Steady state numerical simulations are performed to compare the thermal performances of the fluids and find the minimum velocity that can be applied to achieve the battery pack cooling and temperature uniformity targets. Based on the results, the battery pack, which employs water as the operating fluid, provides the maximum cooling by limiting the temperature to 39.3 °C and the highest temperature uniformity of 6.6 °C at 2 m/s of airflow velocity. Additionally, the minimum velocity required to maintain the temperature uniformity within the acceptable limit of 5 °C is 2.65 m/s. This novel battery pack design can achieve a high level of thermal performance without the requirement of moving parts and high fluid pumping power.