Cooling control effect of water mist on thermal runaway propagation in lithium ion battery modules

Thermal runaway (TR) and its propagation in lithium ion batteries (LIBs) are potential risks during usage, and the likelihood therein is increasing owing to the widespread utilization of LIBs. However, the prevention of LIB thermal hazards remains a technical barrier. In this study, a novel control strategy with water mist (WM) was proposed and investigated through a series of experiments. To comprehensively understand the control mechanisms, the WM cooling effect was discussed by changing the application time and duration. The results showed that WM exhibited excellent cooling capacity with the consumption of 1.95 × 10−4 kg Wh−1 water and TR propagation in the battery module could be easily prevented. During WM application, the maximum cooling rate of LIB exceeded 100 K s−1 and the surface temperature decreased to 373.15 K in a few seconds. Meanwhile, TR propagation hazard could be controlled under much severer condition, where four out of five LIBs in the module were triggered into TR. The cooling process mainly depended on the WM evaporation latent heat and the cooling power for a single battery reached 40.71 W. The critical temperature, Tc1, could be used to forecast the control effect before WM application. And the cooling factor was proposed to determine the cooling effect during hazard control. Thermal hazard could be considered successfully prevented, when LIBs surface temperature reduced below 373.15 K. This work provides fundamental understanding of WM cooling control strategy, indicating the possibility of using this strategy in real cases.