A high-efficiency immersion cooling system with integrated flow distribution plates for vehicle-scale high-energy-density battery modules

Immersion cooling battery thermal management systems (BTMSs) have attracted increasing attention for their high thermal efficiency and significant potential for application in electric vehicles (EVs). In this study, to meet the extreme heat dissipation demands of a high-energy-density, vehicle-scale module during fast charging, an advanced immersion cooling architecture incorporating flow distribution plates (FDPs) was proposed. The target module comprises 48 high-nickel prismatic lithium-ion cells (175 Ah each), with a total capacity of 30.7 kWh. Under 3C charging conditions, the time-averaged volumetric heat generation rate of a battery cell during constant-current charging exceeds 177,000 W/m3. An experimentally validated numerical model was developed to assess thermal performance and guide structural optimization. Key design parameters—including FDP configuration, inlet/outlet orientation, flow direction, cell spacing, and dielectric fluid type—were systematically investigated. The optimized system, featuring chamber flow distribution plates (CFDPs), delivered the best performance, achieving an energy density of 242.94 Wh·kg−1. The optimal design reduced the temperature difference and pressure drop by 79.26 % and 13.43 %, respectively, while maintaining the same maximum temperature as the baseline. Moreover, at a coolant mass flow rate of 80 g s−1, the proposed system outperformed a conventional bottom cold plate BTMS, lowering the maximum temperature and temperature difference to 61.82 °C and 0.67 °C—corresponding to reductions of 18.07 % and 91.82 %, respectively. The pressure drop was also reduced by 79.91 %. This study provides a comprehensive design framework and practical reference for the development of high-performance immersion cooling BTMSs at the large-module or EV battery pack scale.