Li Hao, Wu Xv, Fang Sheng, Liu Mei, Bi Shansong, Zhao Ting, Zhang Xiangjun
National Power Battery Innovation Center, China GRINM Group Corporation Limited, Beijing, China.
China Automotive Battery Research Institute Co., Ltd., Beijing, China.
Front Chem. 2024 Apr 12;12:1403696. doi: 10.3389/fchem.2024.1403696. eCollection 2024.
The phenomenon of fire or even explosion caused by thermal runaway of lithium-ion power batteries poses a serious threat to the safety of electric vehicles. An in-depth study of the core-material thermal runaway reaction mechanism and reaction chain is a prerequisite for proposing a mechanism to prevent battery thermal runaway and enhance battery safety. In this study, based on a 24 Ah commercial Li(NiCoMn)O/graphite soft pack battery, the heat production characteristics of different state of charge (SOC) cathode and anode materials, the separator, the electrolyte, and their combinations of the battery were investigated using differential scanning calorimetry. The results show that the reaction between the negative electrode and the electrolyte is the main mode of heat accumulation in the early stage of thermal runaway, and when the heat accumulation causes the temperature to reach a certain critical value, the violent reaction between the positive electrode and the electrolyte is triggered. The extent and timing of the heat production behaviour of the battery host material is closely related to the SOC, and with limited electrolyte content, there is a competitive relationship between the positive and negative electrodes and the electrolyte reaction, leading to different SOC batteries exhibiting different heat production characteristics. In addition, the above findings are correlated with the battery failure mechanisms through heating experiments of the battery monomer. The study of the electro-thermal properties of the main materials in this paper provides a strategy for achieving early warning and suppression of thermal runaway in batteries.
锂离子动力电池热失控引发的起火甚至爆炸现象，对电动汽车安全构成严重威胁。深入研究核心材料热失控反应机理及反应链，是提出预防电池热失控、提升电池安全性机制的前提。本研究以一款24 Ah商用Li(NiCoMn)O₂/石墨软包电池为基础，采用差示扫描量热法研究了不同荷电状态（SOC）下电池的正极材料、负极材料、隔膜、电解液及其组合的产热特性。结果表明，负极与电解液之间的反应是热失控初期热量积累的主要方式，当热量积累使温度达到一定临界值时，会触发正极与电解液之间的剧烈反应。电池主体材料产热行为的程度和时机与SOC密切相关，在电解液含量有限的情况下，正负极与电解液反应之间存在竞争关系，导致不同SOC的电池表现出不同的产热特性。此外，通过对电池单体进行加热实验，将上述研究结果与电池失效机理相关联。本文对主要材料电热特性研究，为实现电池热失控的早期预警和抑制提供了策略。
