Lithium-ion battery safety assessment and test essentials clarified

The temperature of the lithium ion battery shows the thermal state of the battery. The essence of the lithium ion battery is the heat generation and heat transfer effect of the lithium ion battery. Studying the thermal characteristics of lithium-ion batteries, and their heat production and heat transfer characteristics under different conditions, can make us realize the important way of exothermic chemical reverberation inside lithium-ion batteries. Unsafe behavior The unsafe behavior of lithium-ion batteries, including overcharge and overdischarge, rapid charge and discharge, short circuit, machine abuse conditions, and high-temperature thermal attacks, can easily trigger dangerous secondary reverberations inside the battery and present heat, which can be directly crushed. Passivation film on the appearance of the negative and positive electrodes. When the temperature of the battery cell rises to 130°C, the SEI film of the negative electrode's appearance is resolved, causing the high-activity lithium carbon negative electrode to be exposed to the electrolyte to produce a violent redox response, and the heat presented makes the battery enter a high-risk state. When the internal temperature of the battery rises above 200°C, the passive film of the positive electrode will analyze the positive electrode to produce oxygen, and then continue to react strongly with the electrolyte, presenting a large amount of heat and forming a high internal pressure. When the battery temperature reaches above 240°C, it will also accompany the violent exothermic echo of the lithium carbon negative electrode and the binder. Lithium-ion battery safety evaluation instrument In the lithium-ion battery safety research, the calorimeter is the most important instrument used. The most commonly used calorimeter is accelerated calorimeter, the English name is acceleratingratecalorimeter, ARC. ARC is a new type of thermal elucidation instrument recommended for use in hazardous batch assessment by the connected country. It can provide time-temperature-pressure data of chemical reverberation under adiabatic conditions. ARC is designed based on the adiabatic principle, can use a large sample size, has high agility, can accurately measure the initial temperature of the sample thermal analysis, the change curve of temperature and pressure in the process of adiabatic analysis with time, especially can give differential scanning calorimetry The pressure of materials that cannot be given by the method and the differential thermal analysis method slows the process of change in the thermal analysis. ARC safety assessment method through accurate temperature tracking, to prevent the heat exchange between the tested sample and the situation, so as to provide an approximate adiabatic situation, it is important to conduct a test to clarify the exothermic behavior of the tested sample. In addition to testing thermal runaway, operating the ARC can provide the characteristics of adiabatic conditions. Combining the ARC with a DC constant current source and charging and discharging equipment can test the specific heat capacity of the battery and the adiabatic temperature rise of the charging and discharging process. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Teach the important advantages of 18650 lithium-ion batteries