Experimental investigation of thermal runaway behavior and propagation inhibition of lithium-ion battery by immersion cooling

Understanding the impact of immersion cooling on thermal runaway (TR) behavior and its inhibitory effect on thermal runaway propagation (TRP) is crucial for its practical application. This study explores immersion cooling for individual cells and battery modules, examines the TR behavior of 18,650 single cells at various immersion depths and states of charge (SOC) using filament heating, and investigates TRP between cells. Immersion cooling with a depth of 70 mm significantly extends the interval between the rupture of the battery safety valve and the TR trigger from 70 s (at a 20 mm depth) to 312 s, while reducing the peak TR temperature to 306 degrees C. Additionally, cells with 100 %, 75 %, and 50 % SOC show that higher battery capacity increases the risk of TR and thermal hazards. TRP experiments demonstrate that immersion cooling can inhibit TRP between cells, though safety valves of adjacent cells in 100 %, 75 %, and 50 % SOC battery modules still ruptured, with peak temperatures reaching 118.2 degrees C, 121.4 degrees C, and 111.5 degrees C respectively, posing a potential TR risk. This study highlights the TR behavior of single cells at different immersion depths and confirms that immersion cooling can inhibit TRP, providing valuable insights for the future application of immersion cooling in lithium battery thermal management systems.