Evaluation of lithium battery immersion thermal management using a novel pentaerythritol ester coolant

Immersion cooling is an effective way to control the thermal load of high-power-density energy storage devices. Developing high-efficiency coolants is the core problem and research hotspot to improve immersion cooling performance. In this study, a novel ester coolant, pentaerythritol esters, for battery immersion cooling systems (BICS) was proposed by experiment, and its thermal properties were comparatively studied with other coolants. The effect of coolant flow rate and discharge rate on the thermal performance of BICS was studied. An increase in the discharge rate results in an increase in the maximum battery pack temperature and temperature non-uniformity. However, at a 3-C discharge rate, pentaerythritol esters with a flow rate of 0.015 kg/s can keep the temperature difference of the battery pack below 0.7 K. When the flow rate increases from 0.003 kg/s to 0.045 kg/s, the temperature rise of the battery pack can be reduced by 61%. For all coolants, when the flow rate increases from 0.025 kg/s to 0.045 kg/s, the power consumption increases by 2.3 times. Compared with mineral oil, at a flow rate of 0.045 kg/s, pentaerythritol esters can reduce power consumption by 55.4%. Combined with its renewable, biodegradable features, the novel pentaerythritol ester is a perfect option for the battery immersion coolant.