Thermal Runaway Characteristics of LFP Batteries by Immersion Cooling

Energy storage power stations using lithium iron phosphate (LiFePO4, LFP) batteries have developed rapidly with the expansion of construction scale in recent years. Owing to complex electrochemical systems and application scenarios of batteries, there is a high risk of thermal runaway (TR) and TR propagation, which may result in fires or explosions. In this work, an oil-immersed battery cooling system was fabricated to validate its potential function on high-safety energy storage power stations. The TR characteristics of a 125 Ah prismatic LFP battery immersed in 10# transformer oil were thoroughly investigated via overcharging experiments. The battery under immersion cooling with dynamic flow of coolants displayed the highest cooling rate of 0.143 °C/s compared to the static cooling (0.074 °C/s) and air cooling (0.037 °C/s). Beyond that, the constructed dynamic cooling system decreased the operating temperature of the battery by about 3–5 °C at 1P, primarily attributing to the good heat dissipation. Our findings indicate that the oil-immersed cooling system can prevent both TR of batteries and TR propagation, exhibiting attractive prospects for application in energy storage power stations.