Experimental study on the inhibition effect of intermittent spraying on thermal runaway propagation of lithium-ion batteries in confined space

The rapid development of the new energy sector has brought lithium-ion batteries (LIBs) to the forefront of energy storage and electric vehicles. However, the batteries pose significant risks due to thermal runaway (TR), which can lead to fires and explosions. This study investigates the TR propagation (TRP) characteristics of ternary battery pack in confined space and evaluates the effectiveness of water mist (WM) for cooling. We compare the cooling performance of WM under conditions with and without a top perforated board and assess the effectiveness of intermittent spray (IS) strategies with varying unit time ($t_{u}$) and duty cycle (DC). Continuous spray (CS) for 180s failed to stop TRP. Among various IS strategies, $t_{u}=15 \mathrm{~s}$ with $\mathrm{DC}=0.5$ was most effective in halting TR and minimizing battery damage. In contrast, strategies with $\mathrm{DC}=0.25$ and 0.75 were less effective. The study concludes that IS is superior to CS, with optimal cooling achieved by a $t_{u}=15 \mathrm{~s}$ and $\mathrm{DC}=0.5$ strategy. These findings highlight the importance of optimizing spray strategies for improving the safety and effectiveness of fire suppression in LIBs.