Experimental And Simulation Study On Thermal Runaway And Early Warning Mechanism Of Lithium-Ion Battery

Lithium-ion battery plays a decisive role in China's new energy vehicle macro strategy,the thermal runaway and other security issues are still the key bottlenecks of lithium battery products,the industrialization process.Based on the COMSOL simulation and thermal runaway test,this paper explores the thermal runaway process early warning mechanism and method on the basis of studying the mechanism of lithium ion battery thermal runaway,in order to predict the trends and time of lithium Ion power battery thermal runaway,to provide early warning information to the driver and protect the passengers escape time.The specific work of this paper mainly includes:Based on Comsol Multiphysics,an electrochemical-thermal coupling model of lithium ion battery was established,and the heat generation model of thermal runaway was established.On the basis of the above,the characteristics and the relationship between thermal runaway of the parameters such as the temperature rise rate,the average temperature,the current and the voltage of the lithium ion battery were studied based on the vehicle conditions,the high rate cycle charge and discharge conditions,and the thermal abuse conditions.The results show that the temperature rise rate can significantly characterize the occurrence of thermal runaway.When the temperature rise rate exceeds 1 ? / s,the lithium ion battery has a great probability of thermal runaway.In addition,when the average temperature exceeds 80 ?,lithium-ion battery has a potential risk of thermal runaway.For lithium-ion battery high temperature,acupuncture,overcharge three typical abuse conditions to test.According to the characteristics of current,voltage and temperature of the battery,the macroscopic performance difference of lithium ion dynamic thermal runaway in different misuse experiments was studied.The results show that the high temperature caused by the battery heat runaway takes a long time,the battery temperature is slow.Acupuncture caused the battery heat out of control the most intense,the battery temperature in the needle after a sharp rise in the instant,the battery voltage quickly dropped to 0V.Overcharge conditions,the time required for the battery to run out of heat,the maximum temperature and the highest voltage are closely related to the overcharge current.The greater the overcharge current,the shorter the time required for the battery to run out of heat,the higher the maximum temperature and the maximum voltage.Aiming at the simulation of different high temperature misuse conditions of lithium ion battery,the influence of the temperature on the inflow point temperature,inflection point and the maximum temperature of the battery is studied.The results show that the higher the abuse temperature,the higher the inflection point temperature and the highest temperature of the battery,the shorter the time required for the battery to run out of heat.And the results also show that,in different conditions,the battery temperature characteristics are similar.In this paper,the thermal runaway and its early warning mechanism of lithium ion battery are systematically studied.The results can provide theoretical basis for the establishment of early warning model and the establishment of early warning system.