Abstract The issue of thermal runaway (TR) of Li-ion batteries is a topic of serious concern in electric vehicles and energy storage systems. In this paper, the feature of battery TR, including self-accelerating decomposition temperature, voltage variation, temperature rise, and composition transformation, were comprehensively investigated under various states of charge (SOC). Li-ion batteries with five degrees of SOC from 0% to 100% were tested under four levels of oven temperature from 145 to 205 °C. The response to thermal behavior indicates that the ambient condition can be divided into safe, critical, and hazardous regions. The lower limit of the critical region decreases by about 40 °C when the SOC increases from 0% to 100%. During the transition process of TR, cathode material gradually degrades to small particles and finally turns to powdered metallic oxide, and the inorganic compounds on anode surface become uneven. Through heat flow tests and the modified Thomas model, the critical temperatures of TR were predicted at 212 °C, 220 °C, 179 °C, 164 °C and 183 °C for 0%, 25%, 50%, 75% and 100% SOC cells, respectively. The predictions are close to the critical regions divided by oven tests.

中文翻译：

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锂离子电池热失控临界特性及转变过程

摘要 锂离子电池的热失控 (TR) 问题是电动汽车和储能系统中备受关注的话题。本文综合研究了电池在不同充电状态（SOC）下的自加速分解温度、电压变化、温升和成分转变等特性。在 145 至 205 °C 的四种烘箱温度下，对 SOC 为 0% 至 100% 的五度锂离子电池进行了测试。对热行为的响应表明环境条件可以分为安全区域、临界区域和危险区域。当SOC从0%增加到100%时，临界区的下限降低约40°C。在TR的过渡过程中，正极材料逐渐降解为小颗粒，最后变成粉末状金属氧化物，负极表面的无机化合物变得不均匀。通过热流测试和修正的 Thomas 模型，TR 的临界温度分别预测为 212 °C、220 °C、179 °C、164 °C 和 183 °C，分别为 0%、25%、50%、75% 和分别为 100% SOC 电池。预测接近由烤箱测试划分的关键区域。