锂离子电池安全故障演化过程热行为分析

Thermal Behavior Analysis of Safety Faults Evolution for Li-ion Battery

研究锂离子电池故障过程的行为是提升电池安全的必要手段。通过实验和数值仿真的方法研究了40 Ah方形磷酸铁锂电池在微内短路故障和过充故障过程的热行为。实验验证了三维热模型的可靠性,考虑了电池材料物性对温度的依赖性,剖析了电池温度在故障过程的演化特征和表面测温的有效性。研究发现:电池非工作状态且内短路较严重时(等效电阻小于等于10Ω),故障700 s后表面温升大于2℃,1 h后电池内外的温差超过30℃;严重短路情况下,放电状态故障电池的中心最高温度低于非工作状态电池,但表面温度却高于非工作状态电池;过充故障发生时,换热条件显著影响电池内外温差,绝热条件和对流换热条件下电池内外的温差分别约9℃和2℃。

The investigation of the behaviour of lithium-ion battery failure processes is necessary to improve battery safety.The thermal behaviour of a 40 Ah prismatic Li-ion phosphate battery during micro-internal short-circuit failure and overcharge failure is evaluated by means of experiments and numerical simulations.The reliability of the three-dimensional thermal model is validated,the dependence of the battery material properties on temperature is considered,and the evolution characteristics of the battery temperature during the failure process and the effectiveness of surface temperature measurement are inspected.It is found that:when the battery is non-operating and the internal short circuit is more serious(equivalent resistance is less than or equal to 10Ω),the surface temperature rise is greater than 2℃after 700 s of failure,and the temperature difference between the inside and outside of the battery is more than 30℃after 1 hour;in the case of severe short circuit,the maximum temperature at the centre of the discharged fault battery is lower than that of the non-operating battery,but the surface temperature is higher than that of the non-operating battery;When an overcharge fault occurs,the heat exchange conditions significantly affect the temperature difference between the internal and external battery,and it has been found that the temperature difference between the internal and external battery can reach 9℃and 2℃under adiabatic and convective heat exchange conditions respectively.