Experimental study on the suppression of thermal runaway propagation in nickel-cobalt-manganese lithium-ion batteries by compressed air foam under different spray doses and flow rates in a confined space

Efficient extinguishing agent is the key to solving the lithium-ion batteries (LIBs) fire. This paper took two 106 Ah nickel-cobalt-manganese battery modules as the research objects. A confined space experimental platform was built to explore the influence of the spray doses and flow rate of compressed air foam (CAF) on the suppression of fire. The inhibitory efficacy and mechanism of CAF and water mist (WM) for battery fire were compared. The battery temperature, voltage, mass loss and gas concentration changes during battery fire had been analyzed. The results show that the heat taken away by 20 L CAF and air accounts for 34.21% of the heat generated by the battery. Under the experimental conditions, 20 L is close to the critical spray dose of CAF for suppressing the thermal runaway propagation (TRP). If less than that dose, the battery may suffer thermal runaway or bulging. 10 L/min is close to the critical spray flow rate of CAF for suppressing the TRP. It is found that reducing the flow rate (e.g. 8 L/min) prolonged the contact time between the foam and the battery, which led to more cooling, but also led to more heat conduction between the batteries. Moreover, compared with WM, the fire extinguishing time of CAF is 4.5 s shorter. After spraying, CAF reduced the temperature rebound of the battery by continuous coverage. This study clarified the key parameters for CAF to suppress the LIBs fire, providing a new perspective for the design of LIBs fire safety protection.