LFP电池热失控液氮冷却惰化理论分析方法研究

Study on theoretical analysis method of thermal runaway liquid nitrogen cooling inerting of LPF batteries

传统的商用灭火剂扑救锂离子电池热失控火灾和抑制复燃的效果不佳,液氮作为一种高效的灭火剂,其冷却抑制锂离子电池热失控的效果得到了很多研究机构试验验证,但目前针对液氮灭火用量和灭火效能尚缺乏理论分析方法。笔者通过对液氮灭火机理的理论分析,研究确定了液氮冷却和惰化理论分析计算方法。方法中通过试验和理论分析确定热失控放热热量、液氮吸热热量、液氮惰化用量等,并通过实尺试验验证方法的有效性。以280 Ah磷酸铁锂电池热失控为例,依据理论分析方法,计算得到了惰化抑爆和冷却的最低液氮用量,在有效容积为38.88 m3的爆炸试验箱体内,施加了83.39 kg液氮后,24 h间隔点火48次,均未出现燃爆现象。通过实际案例验证理论分析方法的有效性和合理性,提出的理论分析方法为液氮灭火抑爆的设计和有效性分析提供评价手段和方法,进一步增强磷酸铁锂电池舱式储能系统的安全性。

The traditional commercial fire extinguishing agent is not effective in suppressing the thermal runaway fire and reigni-tion of lithium ion battery.Liquid nitrogen is an efficient fire extin-guishing agent,and its cooling effect on restraining thermal run-away of lithium-ion batteries has been verified by experiments of many research institutions.However,at present,there is a lack of theoretical analysis methods for the influence of liquid nitrogen fire extinguishing dosage and fire extinguishing efficiency.Based on the theoretical analysis of liquid nitrogen fire extinguishing mechanism,the theoretical analysis and calculation method of liq-uid nitrogen cooling and inerting are studied and determined.In the method,experimental studies on thermal runaway heat re-lease,heat absorption of liquid nitrogen,and inert amount of liq-uid nitrogen were carried out,and the effectiveness of the method was verified by full-scale experiments.Taking the thermal run-away of 280 Ah lithium iron phosphate battery as an example,the minimum amount of liquid nitrogen for inerting explosion suppres-sion and cooling is calculated according to the theoretical analysis method.After 83.39 kg of liquid nitrogen was applied to the ex-plosion test chamber with an effective volume of 38.88 m³,the ex-plosion occurred 48 times at a 24-hour interval.The effectiveness and rationality of the theoretical analysis method are effectively verified by practical cases,and the proposed theoretical analysis method provides evaluation means and methods for the design and effectiveness analysis of liquid nitrogen fire suppression and explo-sion suppression,so as to further effectively enhance the safety of lithium iron phosphate battery storage system.