Synergistic Suppression of Lithium-Ion Battery Thermal Runaway by Nitrogen-Driven Ultrafine Water Mist in Confined Combustion Environments

This study introduces a nitrogen-based ultrafine water mist (UWM) method aimed at mitigating thermal runaway in lithium-ion batteries (LIB) during constrained combustion scenarios. Controlled experiments were performed utilizing 18,650-type LIB within an explosion-proof chamber to examine the synergistic effects of nitrogen flow velocity (2–4 m s−1) and mist flow rate (7–33.5 mL min−1). The findings indicate that the nitrogen-assisted UWM system significantly diminished both peak temperature and flame intensity in comparison to traditional fine water mist. The optimal suppression performance was achieved at a flow rate of 7 mL min−1 with nitrogen at 2 m s−1 and 12.5 mL min−1 with nitrogen at 4 m s−1, yielding gas-to-water ratios of roughly 0.9 and 1.0 L mL−1, respectively. The synergistic mechanism arises from convective heat removal by nitrogen and latent heat absorption by ultrafine droplets, hence improving heat transfer and suppressing gas-phase combustion in enclosed environments. These findings offer quantitative direction for the design of sophisticated fire suppression and temperature management systems in energy storage and transportation applications utilizing LIB.