Study On Suppression Of Thermal Runaway Lithium Battery With Water Mist Containing Composite Additives

In air transportation,once the lithium battery occurs thermal runaway,it will seriously threaten the flight safety.At present,the halon fire extinguishing agent equipped on the aircraft cannot effectively suppress the thermal runaway of the lithium battery.However,water mist has good cooling effect and can effectively suppress lithium battery fire.Furthermore,adding additives to enhance the suppression efficiency of water mist has become a hot research topic.In this thesis,based on the action mechanism of different kinds of additives,a series of experiments with water mist containing additives to inhibit the thermal runaway of lithium batteries were carried out on the self-designed experimental platform.The results show that the water mist with additive can effectively inhibit the thermal runaway of the lithium battery,mainly through interrupting the chain reaction caused by thermal runaway.Based on the above work,experiments with different concentration gradients were selected to determine the optimum concentration of each additive.The transmitted energy of lithium batteries after thermal runaway was quantitatively calculated using heat transfer theory.The results show that FC-4,urea and NaCl mainly affect the energy transmitted by the heat radiation between the batteries;triethanolamine,sodium dodecyl benzene sulfonate and sodium lactate mainly affect the energy transmitted by the heat conduction between the batteries;the main influence of NH₄H₂PO₄ and KHCO₃ is decreasing the energy delivered by the heat convection between the cells.Based on the analysis of the influence of the above additives on energy transfer,the composite additive formulation was studied on the basis of obtaining the optimum additive concentration of the single additive.The optimum formula additives obtained include:FC-4,triethanolamine,urea,sodium lactate,N,N-dimethylformamide,and the ratio of various additives was determined.The main mechanism of the formulation is to reduce the surface temperature of the lithium battery and capture free radicals,which greatly enhances the suppression efficiency of the water mist.This study not only enriches the theory of water mist suppresses the thermal runaway of lithium batteries,but also provides reference for the design of fire extinguishing system in aircraft cargo compartment or container,which has practical value for ensuring air transportation safety.