What is the important reason for the fire of the lithium battery pack?

1. Internal short circuit: due to the abuse of the battery, such as the branch crystal caused by overcharge and overdischarge, the impurity dust in the battery processing, etc., it will deteriorate to pierce the diaphragm, cause a micro short circuit, and the release of electrical energy will cause temperature rise and temperature rise The resulting chemical reaction of the material expands the short-circuit path and forms a larger short-circuit current. This mutually accumulating and mutually reinforcing damage leads to thermal runaway. 2. External short circuit: Take electric vehicles as an example. The probability of danger in actual vehicle operation is very low. One is that the vehicle system is equipped with fuses and a battery management system BMS, and the other is that the battery can withstand a short-term high current impact. In extreme cases, the short-circuit point crosses the vehicle fuse and the BMS fails. A long-term external short-circuit will generally cause the weak points in the circuit to be burned, and rarely cause thermal runaway events in the battery. Now, more PACK companies have adopted the method of adding fuses in the loop, which can more effectively prevent the hazards caused by external short circuits. 3. External high temperature: Due to the characteristics of the lithium battery structure, the decomposition reaction of SEI film, electrolyte, EC, etc. will occur at high temperature. The decomposition products of the electrolyte will also react with the positive and negative electrodes, and the cell diaphragm will melt and decompose. The reaction causes a lot of heat to appear. The melting of the diaphragm causes an internal short circuit, and the release of electrical energy increases the heat processing. This cumulative and mutually reinforcing destructive uses will result in the explosion of the explosion-proof membrane of the battery cell, ejection of the electrolyte, and combustion and fire. As the energy source of pure electric vehicles, the important reason for the fire of the lithium battery pack is the thermal runaway caused by the overheating of the battery. This overheating is most likely to occur during the charging and discharging of the battery. Since the lithium battery has a certain internal resistance, a certain amount of heat will appear while outputting electric power to supply power for pure electric power, which makes its own temperature rise. When its own temperature exceeds its normal operating temperature range, it will damage the life of the entire battery. And safety. In pure electric vehicles, the power lithium-ion battery system is composed of multiple power lithium-ion battery cells. During operation, a large amount of heat is collected in the small battery box. If the heat cannot be quickly dissipated in time, High temperature will affect the life of the power lithium-ion battery and even cause thermal runaway, causing accidents such as fire and explosion. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Analysis of the cause of thermal runaway of lithium battery