On the Effectiveness of Aerosol Extinguishing Agents for Battery Vent Gases and Hydrogen

Abstract It is well known that Lithium-ion batteries in thermal runaway can emit gases with high hydrogen concentrations which, in case of delayed ignition, can cause a gas explosion. Aerosol suppression agents are sometimes used to suppress fires and/or prevent ignition of released gases in such situations. The agent has been studied for suppression of fires (diffusion flames), but less is known about the ability of such aerosols to inert highly reactive gas mixtures. In this paper, a commercially available aerosol suppression agent is mixed with a highly reactive gas mixture representing the gas composition from an NCA battery in thermal runaway as well as with pure hydrogen, and the effect on burning velocity is assessed based on OH-PLIF measurements on a Bunsen-burner type setup. The experiments were complemented by 1D flame simulations using a detailed chemical kinetics scheme including relevant combustible gases and the suppression agent. The results show that, although the agent is highly effective in gaseous form, evaporation of aerosols in the pre-flame-zone is prevented by the lower radiative fraction and results in higher burning velocity of hydrogen-rich mixtures. The local cooling induced by the evaporation of the aerosol in the flame leads to an increased flame area and thereby total burning velocity. This effect is further exaggerated by the preferential diffusion of hydrogen. Therefore, modification of the system is needed before applying for this purpose.