Single-phase static immersion cooling for cylindrical lithium-ion battery module

The single-phase immersion cooling is an emerging technology for battery thermal management. Both static- or forced-flow working fluids can be adopted, while the advantages of the static mode are less complexity and low cost. This work proposes a static flow-based immersion cooling method for a six-cell cylindrical Li-ion battery module. The effectiveness of the proposed immersion cooling system is studied at different current rates and compared with conventional air-cooling methods. Experiments find that the maximum cell temperature (Tmax) appears at the end of discharge, and it increases with the C-rate. The proposed immersion cooling system can limit the Tmax below 40 °C and temperature gradient within 3 °C at 3C discharge, exhibiting a superior cooling capability over air cooling. The three-dimensional numerical model has been established to further analyze and optimize the performance of the proposed immersion cooling system. Modelling suggests that immersion cooling has a maximum cooling rate of 2.7 W for the cell with the highest temperature, which is 50% higher than the cooling rate of the forced air-cooling system. In addition, the effects of ambient temperature and liquid volume have been numerically investigated. Different cooling regions are defined to evaluate the thermal-management performance of the immersion cooling system. Finally, the cooling efficiency of three different fluids is compared in a 100-cell battery module, which can provide valuable information for battery thermal management and scientific guidelines for applying immersion cooling for batteries in operation.