液-固复合灭火剂对锂离子电池热失控过程的抑制机理研究

As the airborne Halon 1211 or 1301 extinguishing agent is difficult to interrupt internal exothermic reaction of the lithium ion battery (LIB)，it cannot control the occurrence of thermal runaway of the LIB. Aiming at this problem, the project uses the methods of experiment and theoretical analysis to carry out the following contents by using self-study thermal runaway of LIB test platform: 1) Experiments of the thermal runaway of the LIBs will be carried out. The variation law of characteristic parameters of thermal runaway of the LIBs under the coupling of state of charge and high temperature environment will be explained. The critical conditions of the sudden change (deflation, ignition and thermal runaway) and critical ignition heat flux as well as safe transportation state of charge of LIB will be determined. A prediction model of the time to ignition of the LIBs will be established. 2) Validity tests of liquid-solid composite extinguishing agent on the thermal runaway of the LIBs will be conducted. The impacts of mixing ratio, flow and release pressure of liquid-solid composite extinguishing agent on the characteristic parameters of thermal runaway of the LIBs will be revealed. The critical parameters of liquid-solid composite extinguishing agent extinguishing fire and inhibiting thermal runaway as well as preventing reignition of the LIBs will be explored. 3) The instruments including laser flow field diagnostic test system, high-speed camera and a variety of thermal analysis equipment will be used to in-depth research the spray effect of liquid-solid composite extinguishing agent and jet law of pyrolysis products of LIB as well as the interaction of the liquid-solid composite extinguishing agent and pyrolysis gas of LIB. Based on the above experimental results, the mechanism of collaborative inhibition for liquid-solid composite extinguishing agent will be inferred. The results can provide theoretical basis and data support for the development of thermal runaway mitigation technology of the LIBs transported by air.

飞机使用的哈龙1211或1301灭火剂由于很难阻断锂离子电池（简称“锂电池”）内部放热反应，进而无法控制热失控的发生，针对此问题，本项目拟通过实验和理论分析相结合的方法，利用自研锂电池热失控测试平台开展以下研究：1）锂电池热失控过程测试，阐明荷电状态和高温环境耦合作用下热失控特征参量的变化规律，确定发生突变（放气、点燃和燃爆）的临界判据、临界点燃热流和安全运输荷电状态，建立点燃时间预测模型；2）液-固复合灭火剂抑制锂电池热失控过程的有效性测试，揭示灭火剂的混合比例、流量和释放压力对抑制效果的影响机制，确定灭火剂熄灭明火、抑制热失控和防止复燃的临界参数；2）联合激光流场诊断测试系统、高速摄影仪和多种热分析设备深入研究液-固复合灭火剂的喷射效果和锂电池热解产物的射流规律以及灭火剂与锂电池热解气的相互作用过程，推断灭火剂的协同抑制机理。研究成果为发展锂电池热失控抑制技术提供理论依据与数据支撑。

锂离子电池热失控引发的火灾爆炸事故，严重威胁了飞行安全，机载哈龙1211或1301灭火剂因降温能力有限而无法抑制热失控的发生。针对此问题，本项目采用实验研究和理论分析相结合的方法，对多因素耦合条件下锂离子电池热失控特性和液-固复合灭火剂对锂离子电池热失控的抑制效能和机理进行了深入研究。阐明了锂离子电池热失控行为以及压力、温度和释放气体等热失控特征参量随荷电状态、加热功率和通风量的演变规律，分析了火灾和爆炸危险性，确定了发生放气和热失控等突变行为的临界温度、安全运输荷电状态和热失控触发临界热量，揭示了火灾爆炸机制，建立了热失控时间经验预测模型；量化了电池间热传递量，揭示了热失控扩散过程中的主控机制；研制了环保、高效、绝缘超细干粉灭火剂，阐明了Novec1230、细水雾、ABC类和BC类超细干粉灭火剂对锂离子电池组热失控扩散过程中特征参量变化的影响规律，定量分析了灭火剂的降温效率，筛选出适宜的灭火剂；对比了开放和相对封闭空间细水雾和超细干粉复合灭火剂对大容量锂离子电池热失控的抑制效能，揭示了复合灭火剂混合比例、喷射压力和喷射时机对抑制效能的影响机制，获得了影响协同抑制效应的关键因素，确定了复合灭火剂抑制热失控发生的临界温度，揭示了复合灭火剂的协同抑制机理。研究成果丰富了锂离子电池火灾爆炸机理，为开发锂离子电池热失控和火灾爆炸事故防控技术提供了理论依据与数据支撑。.在国内外学术期刊发表论文7篇，其中SCI论文6篇。申请发明专利16项，其中授权发明专利7项。