Experimental study on the suppression of thermal runaway and fires in lithium-ion batteries using a hexafluorobenzene micelles solution

With the widespread application of lithium-ion batteries (LIBs) in electric vehicles, electrochemical energy storage systems, and other fields, fire safety issues associated with LIBs have become increasingly prominent. As an organic solvent with special properties, hexafluorobenzene possesses a unique gas absorption capability, making it potentially valuable as a fire-extinguishing agent. To verify the effectiveness of hexafluorobenzene in extinguishing LIB fires, a hexafluorobenzene micelles solution was prepared in this study. The extinguishment effectiveness of the hexafluorobenzene micelles solution versus pure water was comprehensively evaluated through theoretical analysis and experimental validation, and the suppressive effects of fire-extinguishing agents released at different stages on LIB thermal runaway (TR) and fire were systematically investigated. The extinguishment mechanisms of the hexafluorobenzene micelles solution were investigated via thermogravimetry and differential scanning calorimetry (TG-DSC). The results indicated that the hexafluorobenzene micelles solution could effectively prevent reignition of LIBs and significantly prolong their reignition time. The maximum cooling power of the hexafluorobenzene micelles solution was approximately 1.17 times greater than that of pure water. Early release of the fire-extinguishing agent was more effective in suppressing LIB TR. The hexafluorobenzene micelles solution extinguished LIB fires and inhibited TR mainly through absorption of TR gases, formation of a water film on the battery surface and the high wetting capacity due to the low surface tension. These findings provide a new idea for the prevention and control of LIB fires.