Experimental Investigation of a Selective Thermoelectric Control Strategy for Li-Ion BTMS under High C-Rate Operation: Balancing Thermal Safety and Uniformity

Thermal management of high-capacity LiFePO 4 pouch cells remains a critical challenge for electric vehicles and electric aircraft, where high discharge rates can induce excessive temperatures and non-uniform thermal distributions. In this study, a selectively controlled direct-contact thermoelectric cooling (TEC) strategy was experimentally investigated using a 20 Ah LiFePO 4 pouch cell. Twelve TEC modules were mounted symmetrically on both major cell surfaces in a distributed 3 × 2 configuration, and each module was independently activated based on local thermocouple feedback when the surface temperature exceeded a predefined threshold of 35 °C. This architecture was designed to provide localized cooling only where required, thereby improving thermal management effectiveness while reducing auxiliary energy consumption. Experimental results showed that under natural convection, the maximum surface temperature remained below the activation threshold up to 4C (33.05 °C), indicating that active cooling was unnecessary under moderate operating conditions. At higher discharge rates, peak temperatures increased to 35.59 °C, 38.34 °C, and 40.37 °C at 5C, 6C, and 7C, respectively. In contrast, the proposed TEC strategy limited the maximum temperature to 35.10 °C, 35.12 °C, and 35.99 °C. The corresponding TEC energy consumptions were 0.29, 0.58, and 1.68 Wh, representing only 0.5%, 1.1%, and 3.3% of the discharged battery energy, respectively. In addition, the calculated cooling capacity and coefficient of performance (COP) ranged from 0.276 to 1.542 Wh and 0.92–0.95, respectively, demonstrating relatively stable energy efficiency under high-rate operation. Although surface temperature nonuniformity increased with discharge rate, Δ T max remained limited to 6.41 °C at 7C. The results demonstrate that the proposed selectively controlled distributed direct-contact TEC architecture can effectively balance thermal safety, temperature uniformity, and auxiliary energy consumption under severe operating conditions. The findings provide practical insights into energy-aware TEC-based thermal management of large-format pouch cells and support its application in high-power electrified transportation systems.