Combustion behavior of lithium iron phosphate battery induced by external heat radiation

The combustion behavior of 50 Ah LiFePO4/graphite battery used for electric vehicle is investigated in the ISO 9705 combustion room. The combustion is trigged by a 3 kW electric heater as an external thermal radiative source, and then the surface temperature, combustion behavior, heat release rate, flame temperature and mass loss rate are obtained. The thermal runaway occurs when the battery surface temperature reaches 126.7 ± 2.2 °C and releases the combustible gases. After its ignition, the combustion generally undergoes first jet fire stage, stable combustion stage, second even third jet fire stage, final stable combustion stage and extinguishes stage. The maximum heat release rate reaches 64.32 kW and the maximum heat release is 13.74 MJ. The heat release rate is closely synchronous with the mass loss rate, and the mass loss ratio reaches to 26.9%. These fundamental data can provide basic knowledge for the battery performance based fire safety design.