【作者】 王涛；

【导师】 陈小雨；

【作者基本信息】 中国矿业大学 ， 安全科学与工程， 2023， 硕士

【摘要】 锂离子电池由于能量密度高、循环性能良好、工作电压高等优点,被广泛应用于移动电子设备、电动汽车、储能电站等领域。近年来,关于锂离子电池引发的安全事故屡见不鲜,严重威胁人们的生命健康和财产安全。目前,仍未找到针对锂离子电池热失控灾害的有效抑制技术。因此,为了有效削弱锂离子电池热失控灾害,亟需开展热失控抑制技术研究。根据锂离子电池热失控灾害的特点和实际应用需求,自主设计了火探管式灭火系统。该系统的特点是以火探管作为电池热失控感知元件,既能在电池热失控发生时自动触发,又能向发生热失控的电池定点输送抑制介质。本文中的火探管式灭火系统选择水作为抑制剂。由于水具有清洁、价廉、冷却效果好的优点,是当前锂离子电池热失控灾害抑制研究的热点材料。在自研的火探管式灭火系统的基础上,本文开展了一系列热失控灾害抑制模拟实验,揭示了火探管式灭火系统的抑灾机理,探索了影响该系统抑灾能力的相关因素。主要工作如下:(1)搭建了开放空间锂离子电池热失控灾害抑制实验平台,研究了在开放空间环境下抑制剂种类、抑制剂使用量和驱动压力对火探管式灭火系统抑灾能力的影响。研究发现:在使用量和驱动压力一致的条件下,水的灭火降温能力要明显优于全氟己酮;系统的灭火降温能力与用水量呈正相关,在1 MPa的驱动压力条件下,25 m L和50 m L使用量的水无法抑制热失控产气的燃烧,随着用水量的增加,电池热失控后不再出现剧烈燃烧现象,电池的表面最高温度与高温持续时间大大降低;在用水量为100 m L的条件下,0.5 MPa的压力未能保证系统及时响应,热失控后的电池出现了明火;驱动压力逐渐增加时,系统能够及时响应,但是其释放的液滴出现了明显的溅射现象,这对系统的冷却降温效能带来了负面影响,当驱动压力为1 MPa时,系统的冷却降温性能最佳。(2)搭建了封闭空间锂离子电池热失控灾害抑制实验平台,开展了封闭空间下的单体锂离子电池热失控实验,研究了抑制剂使用量和驱动压力对火探管式灭火系统抑灾能力的影响。研究发现:封闭空间环境下的锂离子电池发生热失控会有气体爆炸的风险,且热失控后的气体爆炸强度与电池荷电状态呈正相关;系统的抑制气体爆炸能力与用水量和驱动压力呈正相关,在1 MPa的驱动压力下,当用水量为100 m L时,该系统可以完全抑制100%SOC的单体锂离子电池热失控时的产气爆炸。当用水量为100 m L时,驱动压力为0.5 MPa,无法抑制热失控产气爆炸,随着驱动压力的增加,产气爆炸强度降低,直至热失控产气不爆炸。(3)在针对单体锂离子电池热失控灾害抑制的研究基础上,进一步对锂离子电池模组的热失控灾害特性以及火探管式灭火系统的抑制热失控传播能力开展了研究。研究发现:电池模组内某个电池发生热失控会导致其他电池依次发生热失控,且电池模组内的电池在热失控过程中会产生更加复杂的火焰行为;为单节电池配备100 m L的水可以阻止排列方式为1×3和3×3的电池组热失控传播,而同样条件下的全氟己酮的阻止热失控传播能力较差,无法完全阻止3×3电池模组的热失控传播。更多还原

【Abstract】 Due to its high energy density,good cycling performance,and high operating voltage,lithium-ion batteries are widely used in fields such as mobile electronic devices,electric vehicles,and energy storage stations.However,in recent years,safety accidents caused by lithium-ion batteries have been common,posing a serious threat to people’s lives,health,and property.At present,the suppression technology for thermal runaway hazards of lithium-ion batteries is still in the selection stage.Therefore,in order to effectively weaken the harm of thermal runaway in lithium-ion batteries,it is urgent to carry out research on thermal runaway hazard suppression technology.Based on the characteristics and practical application requirements of thermal runaway hazards in lithium-ion batteries,a fire detection tube type thermal runaway hazard suppression system has been independently designed.The characteristic of this system is that the fire detection tube is used as a sensing element for battery thermal runaway,which can automatically trigger when the battery thermal runaway occurs,and can also transport the suppression medium at a fixed point to the battery that generates thermal runaway.Due to the advantages of cleanliness,affordability,and good cooling effect,water is currently a hot material in the research of thermal runaway hazard suppression for lithium-ion batteries.Therefore,water is chosen as the suppression medium for the fire detection tube type thermal runaway hazard suppression system.On the basis of the self-developed thermal runaway hazard suppression system,this article conducted a series of thermal runaway hazard suppression simulation experiments,revealing the disaster suppression mechanism of the fire detection tube type thermal runaway hazard suppression system,and exploring the relevant factors affecting the system’s disaster suppression ability.The main tasks are as follows:（1）We have established an open space lithium-ion battery thermal runaway hazard suppression experimental platform and studied the effects of suppression medium types,medium dosages,and driving pressures on the disaster suppression ability of a fire detection tube type thermal runaway hazard suppression system in an open space environment.Research has found that under the conditions of consistent dosage and driving pressure,the fire extinguishing and cooling ability of water is significantly better than that of C₆F₁₂O;The fire extinguishing and cooling capacity of the system is positively correlated with water consumption.Under a driving pressure of 1MPa,25 m L and 50 m L doses of water cannot suppress the combustion of thermal runaway gas.With the increase of water consumption,the battery no longer experiences severe combustion after thermal runaway,and the maximum surface temperature and duration of high temperature of the battery are greatly reduced;Under the condition of restraining the water consumption of the medium to 100 m L,a pressure of 0.5 MPa failed to ensure timely response of the system,resulting in an open flame in the battery after thermal runaway;When the driving pressure gradually increases,the system can respond in a timely manner,but the released droplets show obvious sputtering phenomenon,which has a negative impact on the cooling efficiency of the system.When the driving pressure is 1 MPa,the cooling performance of the system is the best.（2）We have established an experimental platform for the suppression of thermal runaway hazards of lithium-ion batteries in enclosed spaces,conducted thermal runaway experiments on individual lithium-ion batteries in enclosed spaces,and studied the effects of medium dosage and driving pressure on the disaster suppression ability of a fire detection tube type thermal runaway hazard suppression system.Research has found that there is a risk of gas explosion when lithium-ion batteries experience thermal runaway in enclosed spaces,and the intensity of gas explosion after thermal runaway is positively correlated with the battery’s state of charge;The ability of the system to suppress gas explosions is positively correlated with water consumption and driving pressure.At a driving pressure of 1 MPa and a water consumption of 100 m L,the system can completely suppress the gas explosion caused by thermal runaway of a 100%SOC single lithium-ion battery.When the water consumption is 100 m L and the driving pressure is 0.5 MPa,it cannot suppress the thermal runaway gas explosion.As the driving pressure increases,the gas explosion intensity decreases until the thermal runaway gas does not explode.（3）On the basis of research on the suppression of thermal runaway hazards in individual lithium-ion batteries,further research was conducted on the thermal runaway hazard characteristics of lithium-ion battery modules and the ability of the fire detection tube type thermal runaway hazard suppression system to suppress thermal runaway propagation.Research has found that the thermal runaway of one battery within a battery module can lead to the subsequent thermal runaway of other batteries,and the batteries within the battery module will exhibit more complex flame behavior during the thermal runaway process;Equipping a single battery with 100 m L of water can prevent the thermal runaway propagation of battery packs arranged in ways 1×3 and 3×3,while under the same conditions,C₆F₁₂O has a poor ability to prevent thermal runaway propagation and cannot completely prevent the thermal runaway propagation of 3×3 battery modules.更多还原