Study On Thermal Runaway Characteristics Of Lithium-ion Battery Under Thermal-electric Abuse

In recent years,there have been increasing calls for the protection of the environment and the use of clean energy all over the world.The country has also strongly supported the development and popularization of new energy.The electric vehicle industry has also developed rapidly,and various developments have also appeared in the development process.The most concerned issue is the continuous occurrence of fires caused by thermal runaway of lithium-ion batteries,and the thermal management of lithium-ion batteries has therefore become an important bottleneck restricting the development of electric vehicles.The paper takes a mass-produced ternary lithium-ion battery as the research object,establishes a thermal runaway model of lithium-ion battery in the COMSOL multiphysics software,and uses temperature as a medium to establish a thermal-electric abuse coupling model,which changes from macroscopic parameters Analyze its thermal runaway characteristics and development laws from the perspective of the microscopic reaction mechanism.This article explains the heat generation and heat transfer mechanism of lithium-ion batteries,and then leads to various trigger conditions and factors for thermal runaway;points out the internal side reactions and products of the battery caused by heat accumulation.It provides a theoretical basis for studying the characteristics of thermal runaway of lithiumion batteries under different abuse conditions.Based on the physical structure of the lithium-ion battery,a simplified threedimensional physical model is established,and then different thermal abuse methods are used to trigger thermal runaway,and its thermal runaway characteristics are analyzed from the perspective of external temperature changes and internal reaction mechanisms.Specific heat abuse methods include the temperature of the external heat source,the heating position of the external heat source,and the heat dissipation coefficient.The temperature rise changes of the battery and the temperature field distribution of the diaphragm are analyzed.The research results show that the higher the temperature of the external heat source,the shorter the time for the battery to enter the thermal runaway,the faster the temperature rise,and the greater the maximum temperature;the smaller the heating position,the longer the preparation time for thermal runaway,and once the thermal runaway occurs,the reaction will be more intense;heat dissipation coefficient The smaller the value,the more likely it is for thermal runaway to occur,the more intense the reaction and the longer the duration.In order to improve the consistency of the thermal runaway model with the actual operating conditions,this paper uses temperature as the medium to establish a thermalelectric abuse coupling model.By changing overcharge,the heating position of the external heat source,etc.,the battery temperature changes and production under different operating conditions are analyzed.Thermal power changes,voltage changes and internal resistance changes,etc.The results show that heating at the positive electrode tab is more stable than at the negative electrode tab;overcharging is the most dangerous factor in electric abuse,it will increase the internal resistance of the battery,prolong the heating time,and will cause the voltage to continue to rise,exceeding the battery The upper limit of working voltage makes the battery in a dangerous working condition.The paper studies the characteristics of thermal runaway of lithium-ion batteries under thermal-electrical abuse,and provides guidance for preventing or delaying thermal runaway of lithium-ion batteries...