Huang Li

In order to investigate the suppression effect of different extinguishing agents on lithium-ion battery fires in real confined spaces, a comparative experiment was conducted using aerosols, heptafluoropropane, and perfluorohexanone. In tests without any fire suppression measures, the peak heat release rate reached up to 69.09 kW, and a total of 8.05 MJ of heat was generated along with multiple deflagration events. Moreover, the heptafluoropropane and perfluorohexanone both effectively extinguished the flames with extinguishing times of 12 and 20 s, respectively. The aerosol agent caused a significant contraction of the flames, but it was unable to achieve complete extinguishment. Regarding cooling performance, the heptafluoropropane decreased the front surface temperature of the battery by 147 °C, while perfluorohexanone achieved a reduction of 230 °C. Additionally, the liquid-phase adhesion characteristics of perfluorohexanone enabled sustained cooling. A comprehensive comparison indicates that the perfluorohexanone agent exhibits outstanding performance in flame extinguishment, cooling efficiency, and the suppression of thermal propagation. Heptafluoropropane demonstrates rapid fire suppression and is suitable as a fast-response agent, whereas the aerosol requires a multi-discharge design to achieve reliable performance. Based on these findings, it is recommended that energy storage systems adopt a composite suppression strategy for fire protection.

A thermal abuse model of a single lithium-ion battery, coupling the electric–chemical reaction model and heat transfer model condition, is presented in this work to predict the battery’s thermal response. This model was validated by the experimental results, and it was found that it can predict the battery’s thermal runaway in adiabatic conditions well. It was found that a local hot spot is formed first on the cell nearest the air gap inside the battery. A thermal runaway propagation model was constructed based on this thermal abuse model of a single battery. In addition, the effect of four different modes on the mitigation of thermal runaway propagation is also discussed, including the air gap, cooling plate and insulation layer. The thermal runaway propagation event is successfully prevented when the aerogel is placed between adjacent batteries. However, low-thermal-conductivity insulation material has a negative effect on the heat sink of the battery in thermal runaway, which may aggravate this behavior. This study demonstrates that the model can be used to predict thermal runaway propagation event in battery modules with different prevention measures, and also contributes to the design of safe lithium-ion battery systems.