Ignition and combustion characteristics of lithium ion batteries under low atmospheric pressure

Numerous of lithium ion battery fires or explosions enhance the need of fire control technology. To investigate the effectiveness of depressurization on the fire suppression of lithium ion batteries in an aircraft environment, an experimental and theoretical study is taken on the ignition and combustion characteristics of lithium ion batteries under an incident heat flux of 50 kW/m2 using a low pressure tank. Several fire parameters are measured and analyzed, including time to deflation, ignition and thermal runaway, surface and flame temperatures as well as average mass loss rate. Experimental results show the average mass loss rate and surface and the peak flame temperatures decrease whereas the time to deflation, ignition and thermal runaway increase with the reduction of the pressure, demonstrating a lower fire risk. The 30 kPa is the critical pressure for the ignition of lithium ion battery under 50 kW/m2 radiation heat flux. However, the pressure shows limited influence on the ignition temperature, radiation coefficient and time interval between the time to ignition and thermal runaway. The effect mechanisms of pressure on fire parameters are revealed. An empirical model is developed to predict the average mass loss rate of lithium ion battery under low atmospheric pressure.