Many thermal events have been reported during storage and transport of large numbers of Lithium-ion batteries (LIBs), raising industry concerns and research interests in its mechanisms. Apart from electrochemical failure, self-heating ignition, driven by poor heat transfer could also be a possible cause of fire in large-scale ensembles of LIBs. The classical theories and models of self-heating ignition assume a homogeneous lumped system, whereas LIBs storage involves complex geometry and heterogeneous material composition due to the packaging and insulation, which significantly changes the heat transfer within the system. These effects on the self-heating behaviour of LIBs have not been studied yet. In this study, the self-heating ignition behaviour of a box containing 100 LiCoO 2 (LCO) type of cylindrical cells with different insulation is numerically modelled using COMSOL Multiphysics with a multi-step reaction scheme. The model predicts that the critical ambient temperature triggering self-ignition of the box is 125°C, which is 30°C lower than that for a single cell, and the time to thermal runaway is predicted to be 15 times longer. The effects of different insulating materials and packing configurations are also analysed. This work provides novel insights into the self-heating of large-scale LIBs.

中文翻译：

---

一盒锂离子电池在储存过程中自热点火的数值研究

在大量锂离子电池 (LIB) 的储存和运输过程中已经报道了许多热事件，引起了行业对其机制的关注和研究兴趣。除了电化学故障外，由传热不良驱动的自热点火也可能是大规模 LIB 集合起火的一个可能原因。自热点火的经典理论和模型假设一个均质集总系统，而 LIBs 存储由于封装和绝缘而涉及复杂的几何形状和异质材料成分，这显着改变了系统内的热传递。尚未研究这些对 LIB 自热行为的影响。在这项研究中，使用 COMSOL Multiphysics 和多步反应方案对包含 100 个 LiCoO 2 (LCO) 类型的具有不同绝缘的圆柱形电池的盒子的自热点火行为进行了数值模拟。模型预测触发箱体自燃的临界环境温度为125°C，比单电池低30°C，热失控时间预计延长15倍。还分析了不同绝缘材料和填料配置的影响。这项工作为大规模 LIB 的自加热提供了新的见解。热失控的时间预计要长 15 倍。还分析了不同绝缘材料和填料配置的影响。这项工作为大规模 LIB 的自加热提供了新的见解。热失控的时间预计要长 15 倍。还分析了不同绝缘材料和填料配置的影响。这项工作为大规模 LIB 的自加热提供了新的见解。