Experimental study on the synergistic strategy of liquid nitrogen and water mist for fire extinguishing and cooling of lithium-ion batteries

The frequent incidence of lithium-ion battery (LIB) fires poses a serious threat to both the new energy industry and public safety. Conducting research on controlling LIB fires and thermal runaway propagation (TRP) is imperative. This study systematically compares the characteristics of TRP in battery packs within semi-confined and confined spaces. The cooling performance of liquid nitrogen (LN) on LIB fire under these conditions is assessed. In addition, various synergistic cooling strategies involving LN and water mist (WM) are thoroughly investigated. The results indicate that LN is not effective in suppressing TRP in a semi-confined space. Whereas applying LN for 120 s effectively halted TRP in the confined space, thereby determining the optimal LN quantity needed for effective cooling to inhibit TRP in confined space at 6.87 g/Wh. The synergistic cooling strategies involving LN and WM successfully suppressed TRP in the semi-confined space, with the initial release of WM proving the most effective cooling. The cooling power of LN when applied in combination with WM is approximately three times greater than when applied directly to the battery surface, which guides the design of extinguishing system and process safety assurance of LIB in practical engineering applications.