Thermal performance of a liquid-immersed battery thermal management system for lithium-ion pouch batteries

In order to solve the problems of high temperature rise and large temperature difference of the battery pack, a novel liquid-immersed battery thermal management system (BTMS) for lithium-ion pouch batteries with compact structure and excellent heat dissipation performance was designed. High insulation No.10 transformer oil was employed as the immersion coolant, and the system could operate in active and passive modes. The experimental platform consisting of five 10Ah lithium-ion pouch batteries connected in parallel was constructed to investigate the cooling performance and its influencing factors of liquid-immersed BTMS. The results demonstrated that the liquid-immersed cooling scheme with the immersion depth of 13.2 cm (the full immersion height) and the flow rate of 0.8 L/min exhibited the optimal thermal management performance under the discharge rate of 2C (100A) and the ambient temperature of 25 °C. Compared with that without immersion coolant (i.e. natural air cooling), the maximum temperature decreased from 58.3 °C to 39.4 °C, which fell by 32.4%; and the maximum temperature difference of the battery module decreased from 4.97 °C to 1.23 °C, with a decrease of 75.3%, the cooling performance of BTMS was greatly improved. Hence, the liquid-immersed BTMS would be an effective and suitable thermal management system for lithium-ion pouch batteries.