Performance analysis of a novel battery thermal management system integrating thermoelectric and dielectric immersion cooling in EVs

• A novel BTMS was studied for 2.6 Ah, 26650 LiFePO 4 cells in a 3 × 3 configuration. • Cells were immersed in flowing transformer oil, a dielectric fluid. • 12706 Peltier modules were used as thermoelectric coolers for the fluid. • The maximum temperature drop was 16.5 K at 9.6 C and 1.96 L/min. • The maximum reduction in temperature rise was ∼ 53 % compared to without BTMS. Effective thermal management of lithium-ion (Li-ion) batteries in electric vehicles (EVs) is essential for ensuring safety, extending battery life, and maintaining performance under varying operating conditions. This study presents a novel battery thermal management system (BTMS) that integrates thermoelectric cooling with dielectric immersion cooling, and evaluates its performance through both simulation and experimentation. A relatively new 26650 LiFePO 4 battery model, characterized by high capacity and high discharge capability was selected due to its elevated heat generation. The proposed BTMS was first analyzed numerically using computational fluid dynamics (CFD) to assess temperature distribution and cooling effectiveness. Subsequent experimental testing was performed with a physical battery cell simulator, and the measured data were compared with CFD predictions. In all cases, the experiments yielded slightly higher temperature values than those predicted by simulation. At the maximum coolant flow rate of 1.96 L/min, the BTMS reduced the temperature rise of the battery cell simulator by 28.78 %, 41.52 %, and 46.54 % at discharge rates of 5.8 C, 7.7 C, and 9.6 C, respectively, compared to operation without any BTMS. Under the highest discharge rate (9.6 C), where heat generation was greatest, temperature reductions of 9.71 K, 12.57 K, and 16.57 K were achieved over 375 s for coolant flow rates of 0.58 L/min, 1.08 L/min, and 1.96 L/min, respectively. Overall, the developed BTMS proved highly effective in controlling the temperature of the Li-ion battery cell simulator. The findings offer valuable guidance for designing and implementing thermoelectric–dielectric immersion cooling technologies, particularly for high-performance EV applications.