常压及低压下锂电池热失控随数量变化特性

Research on thermal runaway characteristics of lithium-ion batteries along with cell number changes under standard and low atmospheric pressures

为明确在地面常压环境和商用飞机巡航高度低气压环境下锂电池热失控火灾危险特性随电池数量的变化关系,分别于95 kPa地面常压环境和20 kPa低压环境下,开展不同电池数量梯度的热失控试验,测量热释放速率,总热释放量,烟气温度,CO、CO_(2)和碳氢等气体的实时体积分数。结果表明:最高热释放速率和总热释放量与电池数量均呈幂函数增长,幂函数指数随环境压力降低而减小;随电池数量的增加,95 kPa下燃爆和射流火频发,高温危险性大幅增加,但易燃爆气体峰值浓度相对较低且无明显增加;20 kPa下高温危险性增幅较小较弱,碳氢气体、CO等易燃爆气体体分数大幅增加。

In order to reveal the variation of thermal runaway fire risk characteristics of lithium-ion batteries for different cell numbers under ambient pressure of land surface and cruise altitude,thermal runaway experiments with different cell numbers were carried out at pressure of 95 kPa and 20 kPa.Heat release rate,total heat release,smoke temperature and concentrations of CO,CO_(2) and hydrocarbons were measured.The results show that the peak heat release rate and total heat release grow with cell number in a power function and the index reduces along with the decease of pressure.As the increases of cell number,combustion explosion and jet flame become frequent and thermal hazards increase greatly,but peak concentrations of flammable gases are comparatively lower with no significant growth under pressure of 95 kPa.However,the hazards of potentially explosive gases increase greatly under 20 kPa,such as CO and hydrocarbons.