Thermal runaway is a major safety concern for Lithium-ion batteries in manufacture, storage, and transport. Facing the frequent incidents in the air transport of massive batteries, more reliable fire prediction and protection strategies under low-pressures conditions are urgently needed. Herein, thermal runaway criticality of the open-circuit cylindrical battery piles (up to 9 cells with 30% SOC) under a hot boundary is investigated inside a novel low-pressure chamber (20–100 kPa). Characteristics battery temperatures for the safety venting and thermal runaway are measured to analyze the influences of pressure and cell number on battery failures. Results indicate that lowering the pressure could promote an earlier and stronger safety venting and weaken the intensity of the exothermic reactions inside cells, which is verified by the surface morphology of the electrodes. The overall fire risk is higher with higher pressure and larger battery-pile size, as indicated by the lower minimum boundary temperature for thermal runaway (255 °C~385 °C). Moreover, a simplified heat transfer model is established to explain the trend of thermal-runaway criteria and the influence of the low-pressure environment. This work delivers new insights into the effects of pressure and pile size on battery thermal runaway, which can help to improve the safe storage and transport of large-scale lithium-ion battery piles under varied pressure conditions.

热失控是锂离子电池在制造、储存和运输过程中的主要安全问题。面对海量电池空运事故频发，迫切需要更可靠的低压条件下火灾预测和防护策略。在此，在新型低压室 (20–100 kPa) 内研究了热边界下开路圆柱形电池堆（最多 9 个电池，SOC 为 30%）的热失控临界性。测量安全排气和热失控的特征电池温度，分析压力和电池数量对电池故障的影响。结果表明，降低压力可以促进更早、更强的安全排气，并减弱电池内部放热反应的强度，这可以通过电极的表面形貌来验证。总体火灾风险随着压力和电池堆尺寸的增加而增加，如热失控的最低边界温度较低（255°C~385°C）所示。此外，建立了一个简化的传热模型来解释热失控标准的趋势和低压环境的影响。这项工作为压力和堆大小对电池热失控的影响提供了新的见解，有助于提高大型锂离子电池堆在不同压力条件下的安全储存和运输。建立了一个简化的传热模型来解释热失控标准的趋势和低压环境的影响。这项工作为压力和堆大小对电池热失控的影响提供了新的见解，有助于提高大型锂离子电池堆在不同压力条件下的安全储存和运输。建立了一个简化的传热模型来解释热失控标准的趋势和低压环境的影响。这项工作为压力和堆大小对电池热失控的影响提供了新的见解，有助于提高大型锂离子电池堆在不同压力条件下的安全储存和运输。