The enhanced cooling effect of water mist with additives on inhibiting lithium ion battery thermal runaway

As the most concerning failure event of lithium ion batteries (LIBs), thermal runaway (TR) often causes considerable damage, such as fire or even explosion. Therefore, an efficient cooling method is essential after LIBs are triggered into TR. In this study, a series of experiments are performed on LIBs TR using water mist containing different additives to investigate the cooling performance of additives; furthermore, its cooling mechanism is described. The results show that water mist containing Tween 20 or 1-heptanol can enhance heat transfer, whereas FS-51 inhibits heat transfer. The heat dissipation of Tween 20 is 12.46 ± 0.20 kJ, which exhibits the best cooling effect, and it is increased by 23.6% compared with the test with pure water. However, the binary mixture of Tween 20 and 1-heptanol does not exhibit a better cooling performance than the water mist with a single additive. Moreover, the enhanced cooling effect of water mist with additives is closely related to the surface tension and foamability of additives. The additive with lower surface tension and foamability exhibits a better cooling effect of water mist. These results demonstrate that water mist containing specific additives improves the cooling effect, which may provide a reference for the design of battery safety.