Experimental study on suppression of thermal runaway propagation of lithium-ion battery by salt hydrate based dry powder extinguishants

To develop the high cooling effect, high fire extinguishing performance, non-conductive and low cost extinguishant for fighting lithium -ion battery (LIB) fire, seven salt hydrates with different amounts of crystal water were systematically studied as the dry powder extinguishants in this work. The results of the differential scanning calorimeter (DSC) measurement demonstrate that the highest endothermic enthalpies of the salt hydrates below 150 degrees C is larger than 800 kJ kg -1 , which can effectively suppress the thermal runaway (TR) propagation between LIBs. Moreover, the heat absorption capacity of the salt hydrate can be enhanced by increasing the reaction entropy, which can be achieved by increasing the crystal water content. The electric breakdown voltages of the salt hydrates were ranged from 4 kV to 60 kV, which are mainly determined by the crystal water content and the melting point. Furthermore, the fire extinguishing performances of the salt hydrates have no obvious relationship with their heat absorption capacities, but are related to their chemical component. This work systematically studied the factors that affect the cooling effect, the fire extinguishing performance and the conductivity of the salt hydrates, which provides an essential basis for developing high performance salt hydrate based dry powder extinguishants in fighting LIB fire.