Abstract: In order to investigate the thermal runaway characteristics of lithium battery in civil aviation transportation under low pressure environment such as takeoff, approach and cruise, this paper uses external heat source to trigger thermal runaway of lithium battery under the environmental pressure of takeoff, approach (90 kPa) and cruise (20 kPa) respectively. The thermal runaway characteristics of 21700 cylindrical and soft packed lithium batteries are explored and compared by analyzing the thermal runaway phenomenon, the change of the battery surface center temperature, the heat release rate and the smoke during the thermal runaway process. The experimental results show that the thermal runaway strength of 21700 cylindrical and soft packed lithium batteries will be reduced when the ambient pressure decreases; When the ambient pressure drops from 90 kPa to 20 kPa, the surface center temperature of 21700 cylindrical and soft packed lithium batteries decreases from 603.2 ℃ and 686.4 ℃ to 420.6 ℃ and 627.3 ℃ respectively, and the thermal runaway trigger temperature increases from 218.5 ℃ and 134.5 ℃ to 230.8 ℃ and 158.4 ℃ respectively. Under the environment of 90 kPa and 20 kPa, the CO2 content produced by the soft packed lithium battery with unit capacity is higher than that of the cylindrical lithium battery, but the CO content produced is less than that of the cylindrical lithium battery.

Key words: transport aviation, lithium battery, low pressure, thermal runaway, packaging form