Preparation of a novel aqueous vermiculite dispersion fire extinguishing agent to inhibit lithium-ion battery fires

A novel modified aqueous vermiculite dispersion (MVD) extinguishing agent for lithium-ion battery (LIB) fires was developed by dispersing a modified vermiculite (VMT) composite powder in an aqueous solution. To provide the desired MgAl-LDH/VMT composite, abundant MgAl-layered double hydroxide (MgAl-LDH) platelets were grown on the VMT layers via a hydrothermal method. Compared to the original VMT, which exhibited a heat absorption enthalpy of 712 mJ/mg, the MgAl-LDH/VMT composite powder had a significantly increased value of 1795 mJ/mg, indicating that MgAl-LDH/VMT absorbed a greater amount of heat. Then, the extinguishing performance of the MVD was thoroughly investigated for 173 Ah lithium iron phosphate (LFP) battery fires. Considering the resulting extinguishing time, cooling, and toxicity-suppressing effects, it was deduced that, compared with water mist, the MVD had a superior performance to water mist. Notably, the MVD extinguished the fire within 1 s, and after release, the temperatures around and above the safety vent and the negative tab were lower than those when water mist was employed. The emission of some harmful gases was also dramatically reduced compared to the cast of water mist.