Exploiting activation-timing effects in thermoelectric cooling for energy-efficient operation of a hybrid battery thermal management system

High-rate discharge challenges the simultaneous control of battery temperature, temperature uniformity, and cooling energy use. A compact thermoelectric cooler (TEC)–heat pipe (HP)–liquid cooling hybrid battery thermal management system (BTMS) is developed for cylindrical lithium-ion battery packs. A validated three-dimensional transient multi-physics model couples battery heat generation, solid heat transfer, thermoelectric conversion, and coolant flow. Under 5C discharge, natural convection yields a maximum battery temperature of 366.09 K, whereas the hybrid system limits the maximum temperature and temperature difference to 316.38 K and 2.65 K, respectively. Increasing TEC current strengthens cooling but reduces energy efficiency, while increasing coolant flow improves hot-side heat rejection with diminishing returns. At 1.4 A and 15 g/s, the maximum temperature, total energy consumption, and overall coefficient of performance are 316.53 K, 3.64 Wh, and 2.74, respectively. Under the same TEC current and active duration, shifting TEC operation to the later discharge stage increases the system-level COP total by 15.1% at 4C and 25.6% at 3C, because later activation increases the cold-side temperature and reduces the temperature difference across the TEC at cooling onset. Exploiting these activation-timing effects, a temperature-triggered two-stage strategy is developed. Relative to full-cycle operation at the 1.4 A reference current, it reduces energy consumption by 89.8% at 3C and 68.5% at 4C while maintaining maximum temperatures of 316.33 and 316.83 K, respectively. These findings provide guidance for the energy-efficient design and operation of TEC-assisted BTMSs.