Study On The Thermal Runaway Mechanism Of Lithium-ion Power Battery For Vehicle Under Low Pressure Environment

This study corresponds to the"oil-to-electricity"work of civil aviation special operation vehicles and follows the national green environmental security movement.Lithium-ion batteries（LIBs）are increasingly being used in plateau low-pressure settings,and their thermal safety issues are also attracting attention.We use a combination of experimental and theoretical methods to investigate the thermal runaway of LIBs at different low ambient pressure in this article.On the one hand,we use the FRC2000 dynamic temperature chamber,which can simulate different low-pressure conditions,and combine it with the Ttech-ISO9705calorimeter to build an experimental platform.On the other hand,the pressure correction coefficient k_p is applied to create a thermal runaway reaction kinetic model suitable for LIBs under various low pressure conditions,based on previous studies on the thermal abuse model of LIBs and considering the effect of ambient pressure on the thermal runaway mechanism of LIBs.The experimental results show that:（1）The thermal characteristics parameters expressed by the cell’s peak temperature,peak heat release rate,and total heat release indicate a declining pattern as ambient pressure decreases,and the thermal runaway intensity weakens.With the decrease of ambient pressure,the thermal runaway trigger moment t₁ of the battery is advanced.At 50 kPa,the thermal runaway trigger moment t₁ is 462 s,which is 177 s earlier than the thermal runaway trigger moment t₁ at 90 kPa.（2）The peak concentrations of the four measured pyrolysis flue gases at different ambient pressures were counted.The findings revealed that as the ambient pressure declined,improvements in the concentrations of different gases followed exactly opposite trends:1The peak concentrations of the non-combustible gases represented by CO₂ and NO showed a decreasing trend,and the results indicated that the generation of this type of gas decreased with the decrease of ambient pressure;2 The peak concentration of flammable gases represented by CO and C_xH_y decreases,and the volume of this form of gas produced increases as ambient pressure decreases.（3）In the thermal runaway experiments at different ambient pressures,it was found that the drop of battery voltage was slightly earlier than the rapid rise of temperature.There is no positive or negative correlation between the time intervalΔt between voltage dip and temperature rise and environmental pressure,and the average time interval is about 13s.The simulation results indicate that:the error of the thermal runaway trigger moment t₁ can be controlled within±2 s,and the error of the thermal runaway peak temperature T7_maxcan be controlled within±2℃.The error is held within an acceptable range,and the model will simulate the thermal runaway temperature profiles of LIBs at different low ambient pressures more accurately.