Experimental Study of a Direct Immersion Liquid Cooling of a Li-Ion Battery for Electric Vehicles Applications

The aim of this work is to test a battery thermal management system by direct immersion of a commercial 18650 LiFePO4cell in a low boiling dielectric liquid. It is worth noting that for electric mobility applications, thermal management of Lithium-Ion batteries is a fundamental issue because batteries experience high discharge currents and temperatures. First, we present an electrical characterization of the Lithium-Ion by measuring cell potential, open circuit potential and entropic heat coefficient. Temperature measurements were carried out with thermocouples and infrared thermography. A simplified heat generation term was evaluated using the experimental data. Then, the same battery was immersed in a dielectric low boiling liquid and tested under three different discharge currents. For comparison, also the case without dielectric liquid was analyzed. This paper demonstrates the feasibility of a thermal management system based on direct immersion of a battery cell in a low boiling dielectric fluid. Indeed, the results show a substantial decrease of battery temperature when immersed.