Nanofluid-Based Counterflow Immersion Cooling for Lithium-Ion Battery During Fast Charging

Abstract Immersion cooling technology holds significant potential for Lithium-ion battery thermal management. This paper proposes a counterflow-based battery thermal management system (BTMS) under fast charging conditions, using a high thermal conductivity silicone oil–based nanofluid as the coolant. Experimental equipment has been used to extract battery-related parameters, along with the experimental test bed for validation of the nanofluid immersion cooling modeling. The performance of CuO nanofluid, at a 5% volume fraction, was found to reduce the maximum temperature by 1.09 °C and 32.59% in temperature difference compared to the base fluid. The impact of various nanofluid parameters on the thermal performance of the system was analyzed, revealing that increasing the nanofluid volume fraction can reduce both the maximum temperature and temperature difference. Furthermore, a comparison between direct flow design and counterflow design revealed that the counterflow configuration, with optimal separators location from the top of the box, with the middle of the battery under the returning flow while the upper and lower parts under the directly entering flow, outperformed the direct flow design, achieving a 1.22 °C reduction in the highest average temperature and 2.79 °C reduction in the maximum temperature. Therefore, this innovative structure can significantly enhance the temperature uniformity and thermal efficiency of the battery.