Experimental Study of a Thermal Cooling Technique for Cylindrical Batteries

Lithium-ion (Li-ion) batteries have been considered the most promising power source for road transportation. However, the performance and lifespan of Li-ion batteries are strongly dependent on the working temperature. The optimal working temperature is usually within a narrow range, from 25 to 40 degrees C, and the non-uniformity is usually required to be lower than 5 degrees C. Therefore, the industry is seeking a thermal management system that is lightweight, simple-structure, energy-saving, and environmentally friendly. Air-cooling, liquid-cooling, and phase-change material (PCM) are the three most common cooling methods in the literature. In this study, a new concept of hybrid-cooling which utilizes all the three cooling methods is proposed. The concept can use either normal tap water or the condensate from a vehicle's air-conditioner as the coolant source. Also, the coolants can be released back to the ambient environment instead of a coolant recirculation system to reduce weight and complexity. The concept was studied in detail experimentally using the 26,650 Li-ion batteries. The results indicate that the proposed hybrid-cooling concept reduced the maximum surface temperature by about 83%, 70%, and 57% compared with the other three cooling methods: the no-cooling, air-cooling, and water-cooling test results, respectively. Additionally, the concept successfully maintained the temperature uniformity below the recommended 5 degrees C.