Research On Thermal Runaway Propagation And Barrier Of Vehicle Power Battery Module

The thermal runaway of the power battery cell and its propagation not only lead to the failure of the battery pack and even cause the electric vehicle fire accidents,which seriously threaten the life and property safety of the occupants,and have become a pain point in the process of scientific research and product development.Based on the in-depth investigation and analysis of the thermal runaway accidents of the power battery of new energy vehicles,this paper combines the science and technology plan project to research the basic principles,methods,and structural impact parameters of the thermal runaway and thermal runaway barrier of electric vehicle’s battery cells,modules and battery packs.The research goal is to obtain thermal runaway and its propagation law,and discuss barrier measures after single battery thermal runaway occurs,thus gaining time for fire rescue and reducing fire damage.Research work helps to improve and enhance the design safety of electric vehicles.This paper studied the mechanism of thermal runaway propagation in battery module.A real electric vehicle battery module thermal runaway combustion accident was analyzed,and the development process of the battery thermal runaway spread to the vehicle combustion was restored.The 12 Ah prismatic lithium battery cell thermal runaway experiment and the battery module thermal runaway propagation experiment were carried out,focusing on the analysis of the experimental phenomena,changes in battery temperature,changes in battery voltage,and changes in battery ambient temperature in the process of thermal runaway,obtained the evolution process and behavior law of the single battery thermal runaway propagates to the module thermal runaway.Constructed and verified the thermal runaway propagation model of the battery module.Based on the structural characteristics of the battery and the heat generation mechanism of the thermal runaway side reaction,a single battery thermal runaway model was built.Combined with the single battery thermal runaway model and heat transfer principle,a battery module thermal runaway propagation model was built,and the reliability of the model was verified by comparison with the thermal runaway propagation experiment results.Combining the results of experiments and simulations,the countermeasures against thermal runaway propagation were discussed.Designed thermal runaway propagation blocking solutions and carried out related experiments.Three thermal runaway blocking solutions were proposed for heat insulation,heat dissipation,and heat dissipation first and then heat insulation between batteries.Then respectively place aerogel board,aluminum board,aerogel board-aluminum board-aerogel board composite structure between the batteries to conduct thermal runaway propagation experiments.Focusing on the analysis of the experimental phenomena,changes in battery temperature,changes in battery voltage,and changes in battery ambient temperature in the process of thermal runaway,then came to conclusions that the heat insulation between the batteries could significantly reduce the thermal runaway propagation speed,the heat dissipation between the batteries could significantly reduce the severity of thermal runaway,dissipate heat firstly and then insulate heat between the batteries could stop the propagation of thermal runaway.Based on the thermal runaway propagation model,the influencing factors of the thermal runaway propagation barrier were analyzed.The ambient temperature in the thermal runaway propagation model was changed,and the influence of the ambient temperature on the thermal runaway propagation was obtained.Two thermal runaway propagation barrier models were constructed and verified.The parameters of the barrier model including the thickness of the thermal insulation board,the material of the thermal insulation board,and the thickness combination in the first heat dissipation and then thermal insulation structure were changed to obtain the influence law of each parameter change on the blocking effect of thermal runaway propagation.Through examples,the optimal parameters of the barrier structure composed of aluminum board-aerogel board-aluminum board were obtained.