Research On Thermal Runaway Propagation Of Battery Module Based On Phase Change Material And Liquid Cooling

Electric vehicles have gradually become the development trend of the automobile industry,and their application and promotion have alleviated the environmental pollution and energy shortage problems facing the world to a certain extent.But recent electric car fires have raised concerns about the safety of battery cars.As the core part of electric vehicles,the safety of battery seriously affects the reliability of electric vehicles.Therefore,it is very important to study the thermal characteristics of battery cells and modules under normal working and abuse conditions to improve the battery safety.In this paper,a thermal management model of battery modules based on PCM and liquid cooling is proposed to study the impact on the battery safety.In this paper,the working principle and heat generation mechanism of lithium ion battery are analyzed,and a one-dimensional electrochemical model and a threedimensional heat transfer coupling model are established to study the temperature change of the battery during normal charging and discharging.The results show that the temperature of battery charging is higher than that of discharging.Subsequently,a charge and discharge model of the battery module is established to study the influence of charge and discharge ratio on the maximum temperature and maximum temperature difference of the battery module.The results show that when the charge and discharge ratio reaches 4C,the maximum temperature exceedes 46.8℃.When the charge-discharge ratio is 7C,the maximum temperature difference reaches 6.5℃,which seriously affects the normal operation of the battery module..On the basis of the electrochemical and thermal coupling model established above,the internal short circuit model and the side reaction equation are coupled,and the thermal runaway model of the cell under the condition of abuse of penatration is established,which is used to analyze the thermogenic mechanism and internal material decomposition during the battery acupuncture process.Based on this,the model of thermal runaway propagation of battery module is established,and the results showes that the time interval of thermal runaway propagation of battery gradually decreases.The battery acupuncture abuse thermal control experiment platform is built,and the battery single and module acupuncture experiments are carried out respectively to verify the reliability of the model.Then the effects of ambient temperature and battery arrangement on the thermal runaway propagation of battery modules are discussed.The thermal management model of the battery module based on PCM and liquid cooling is established to study its cooling effect on the battery modules under normal working state and thermal out-of-control state respectively.It is found that the model can greatly reduce the maximum temperature of the battery module and effectively improve its temperature uniformity.The influence of filling material,initial temperature and flow rate of coolant on the battery module is analyzed.Further study found that the model also has a certain inhibitory effect on the thermal runaway propagation of battery modules,and the time of thermal runaway occurred in each battery is delayed to a certain extent.Then the influences of PCM thickness,coolant flow,coolant flow parameters,aluminum plate thickness and heat insulation plate on the thermal runaway propagation of the battery module are analyzed.Finally,the influence of the above parameters on the battery module temperature is analyzed comprehensively.