Explosion hazard of thermal runaway in aviation lithium-ion batteries under low-temperature cycling aging conditions

The thermal runaway reactions of lithium-ion batteries exhibit significant deviations following full life-cycle cycling aging when compared to their fresh-state counterparts, particularly under low-temperature conditions. These conditions more closely simulate the operational scenarios encountered in low-altitude aviation, where the risk of catastrophic failure in battery systems is heightened. This study, utilizing a custom-built platform designed for testing thermal runaway and gas explosion phenomena, systematically investigates the impact of low-temperature (-10°C) cycling aging on the associated explosion hazards. Key parameters analyzed in this research include the initiation time of thermal runaway, the peak surface temperature of the battery, the overpressure generated during thermal runaway, the lower explosion limit (LEL) of the gases produced, and the explosion pressure and temperature—each serving as crucial indicators of the system’s safety performance. Experimental results demonstrate that, under ambient temperature conditions, aged batteries exhibit a marked increase in the thermal runaway initiation time, as well as a notable extension in the interval between the activation of the safety valve and the onset of complete thermal runaway (Δt), when compared to fresh batteries. Specifically, thermal runaway occurs at 559.86 seconds, while Δt increases to 122.56 seconds. Moreover, the LEL of hazardous gases rises by 30.95%, and the resulting explosion pressure diminishes to 0.2586 MPa, suggesting a reduced likelihood of catastrophic failure. However, when subjected to low-temperature cycling aging, the explosion risk profile shifts dramatically. In this case, the thermal runaway initiation time is significantly reduced to 412.38 seconds, with Δt contracting sharply to 56.66 seconds. Furthermore, the LEL of the gases decreases by 20.49%, while the explosion pressure surges to 0.3195 MPa, indicating an elevated risk of severe explosion. The multifaceted analysis of these hazard indicators reveals a complex interplay between aging processes and environmental conditions, profoundly influencing the explosion risks and thermal runaway behavior of lithium-ion batteries. These findings emphasize the critical necessity of developing advanced battery management systems that incorporate predictive early-warning mechanisms, strategic battery layout designs, and improved containment strategies, specifically tailored to the demands of electric aviation. By incorporating the effects of both cycling aging and low-temperature environments into risk assessments, this study provides vital insights for mitigating the elevated hazards associated with thermal runaway and the explosion of emitted gases in aviation applications. Ultimately, these findings contribute to the enhancement of safety protocols and risk mitigation strategies for the reliable and secure operation of lithium-ion battery systems throughout their entire operational lifecycle.