Thermal management of lithium-ion battery pack under demanding conditions and long operating cycles using fin-enhanced PCMs/water hybrid cooling system

Abstract

A fin-enhanced hybrid cooling system combining phase change material (PCM) and liquid cooling is designed and optimized in this work to ensure the stable operation of lithium-ion battery under high ambient temperature, high discharge rate or long operating cycles, which is a challenging and burning issue. The coupling effects of composite PCM, fin arrangements, cooling water inflow schemes, and ambient temperature on the heat dissipation performance of battery pack are numerically studied. The maximum temperature can be reduced by up to 7.66 °C with expanded graphite modified PCM at 5C discharge rate and 40 °C ambient temperature, and the optimal mass fraction is found to be 12–16%. The arrangement of composite fins and two-layer PCM can further improve adaptability with better temperature control or temperature uniformity, and the suitable ranges of ambient temperature, coolant inlet temperature and velocity for safe operation are obtained. In general, the hybrid cooling system with fins and counter flow can be used for the thermal management design of batteries used at high temperature of 40 °C and high discharge rate of 5C, and the temperature and temperature difference can be controlled to within 46.2 °C and 4.2 °C respectively. The hybrid cooling system also offers a reliable cooling performance during 2C rate of charging and discharging cycle process, and the temperature and temperature difference can be controlled below 42.2 °C and 1.7 °C respectively.