Investigation of a novel passive self-adaptive battery thermal regulator combining liquid immersion and PCM

Abstract

Battery thermal management is a significant technology for guaranteeing a safe and efficient operation. The hybrid battery thermal management system (hybrid BTMS), which combines phase change materials(PCM) and liquid cooling, is recognized as a promising method. However, studies on wide temperature range adaptive BTMS research are still limited. Efforts still need to improve the thermal management performance for a wide temperature range. To fill this research gap, a novel PCM-immersion hybrid thermal regulator, that adopted PCM and immersion coolant as internal heat absorption medium and utilized the cooling plate as the external heat sink, is proposed for application in BTMS for both high- and low-temperature environments. The volume change of PCM is cleverly used to achieve dynamic switching between air and liquid as the medium between the battery and the cooling plate, realizing the passive-adaptive to ambient temperature variation. A 3D transient model of a 280 Ah Li-ion battery module with the thermal regulator was developed. The influence of initial immersion depth, battery-cooling plate spacing, discharge rates, and ambient temperature were comprehensively studied. The optimal geometry design indicates an 80 mm initial immersion depth and a 3 mm battery-cooling plate spacing. For an ambient temperature of 25 °C, the maximum temperature and the maximum temperature difference were respectively below 38.46 °C and 2.95 °C at consecutive 0.5C discharge–charge cycles. At a -30 °C environment temperature, a 35 °C battery module’s heat preservation time above 0 °C was prolonged to 12,000 s. Additionally, the battery module with hybrid BTMS realized potential acceptable thermal insulation. From a cold state of -20 °C, when discharging at 0.25C, it can reach the allowable minimum charge temperature of 0 °C, and the capacity retention rate is 74.6%.