Abstract:

To study the types and safety of thermal runaway gas released by lithium-ion batteries in an aviation transformer environment, an independent closed-type transformer laboratory was constructed for conducting related experiments. The thermal runaway characteristics of terrapin lithium-ion batteries with 100% state of charge were investigated under different pressure environments (101, 70, and 30 kPa). The temperatures of the lithium batteries during thermal runaway and the pressure changes within the closed laboratory chamber were recorded to compare the thermal runaway characteristics under varying pressure conditions. The resulting thermal runaway gas was analyzed using a gas chromatograph-mass spectrometer, and an independent explosion limit test platform for lithium batteries was developed. Composition analysis and explosion risk analysis were performed to assess the thermal runaway gas produced by lithium batteries. The findings indicate that as the ambient pressure decreases, thermal runaway is triggered earlier; however, the risk of high temperature and gas shock is reduced. Additionally, the composition and content of gases produced vary with different pressure environments. As environmental pressure decreases, the content of CO₂ decreases, while the content of unsaturated hydrocarbons such as C₄H₈, C₄H₆, and C₅H₁₀ increases. This is also the reason for the greater risk of explosion in low-pressure environments. The range of thermal runaway gas explosion for lithium-ion batteries expands with decreasing pressure, resulting in a greater risk. These research results provide a theoretical basis for the safety research of lithium-ion batteries in aviation and offer data references for the safety prevention and control of lithium batteries.

Key words: environmental pressure, lithium-ion battery, thermal runaway, gas detection, explosion risk