基于气体在线监测的磷酸铁锂储能电池模组过充热失控特性

磷酸铁锂储能电池的热失控预警是其大规模推广应用急需解决的问题。首先分析了磷酸铁锂电池热失控产气机理,以硬壳磷酸铁锂电池模组和软包磷酸铁锂电池模组作为试验对象,分别由32块单体电池4并8串组成和72块软包单体电池6并12串组成,搭建与真实储能舱环境一致的试验平台。通过恒流过充的方式研究硬壳和软包磷酸铁锂电池模组过充至热失控的全过程,并采用可见光摄像头、气体探测器、红外监控系统进行全方位的产气在线监测。试验结果表明:磷酸铁锂电池过充至热失控燃烧是一个渐变的过程,并不是突变的;硬壳磷酸铁锂电池和软包磷酸铁锂电池过充热失控特性存在差异,但产气类型及气体质量浓度变化趋势基本一致;磷酸铁锂电池热失控各阶段反应现象与气体的质量浓度变化存在相互联系,可将H2、CO、CO2作为一级预警,HCl、HF作为二级预警,通过监测气体质量浓度变化,在过充的早期阶段做好应对措施,避免储能电池进一步热失控燃烧。研究结果可为磷酸铁锂储能电站的预警和消防提供有效的理论和试验支撑。

Overcharge and Thermal Runaway Characteristics of Lithium Iron Phosphate Energy Storage Battery Modules Based on Gas Online Monitoring

The thermal runaway warning of lithium iron phosphate battery for energy storage is an urgent problem waiting to be solved in large-scale application. Firstly, the mechanism of thermal runaway gas production of lithium iron phosphate batteries is analyzed, and hard-shell lithium iron phosphate battery(composed of 32 single cells in four-in-eight series) and soft-packed lithium iron phosphate battery(composed of 72 single cells in six-in-twelve series) are used as test objects. The test platform is consistent with the real environment of energy storage cabin. The whole process of overcharge of hard shell and soft pack lithium iron phosphate battery module to thermal runaway is studied by constant current overcharge method. The visible light camera, gas detector, and infrared monitoring system are used for all-round on-line monitoring of gas production. The experimental results show that the overcharge to thermal runaway combustion of lithium iron phosphate batteries is not a sudden change but a gradual process. There are differences between hard-shell lithium iron phosphate batteries and soft-packed lithium iron phosphate batteries in overcharge thermal runaway characteristics, but the trend of gas production type and gas concentration is basically the same. Reaction phenomena of lithium iron phosphate batteries in different stages of thermal runaway are interrelated with the change of gas concentration. H2, CO and CO2 can be used as the first-level warning, HCl and HF can be used as the second-level warning. By monitoring the change of gas concentration, countermeasures can be taken in the early stage of overcharge to avoid further thermal runaway combustion of energy storage batteries. The results of this study can provide effective theoretical and experimental supports for early warning and fire prevention of lithium iron phosphate energy storage power plant.