Is thermal runaway serious for lithium batteries?

Thermal runaway occurs on a battery in the lithium battery pack. The high temperature released by the thermal runaway battery will cause the thermal runaway to spread inside the battery pack and cause serious consequences. Therefore, how to guard against thermal runaway of lithium batteries and how to prevent thermal runaway from spreading inside the battery pack has become the focus of attention. Regarding lithium batteries, thermal runaway is the most serious safety accident. The thermal runaway of lithium batteries is due to the fact that the heat production rate is much higher than the heat dissipation rate. A large amount of heat accumulates inside the lithium battery, causing a rapid rise in the temperature of the lithium battery, causing the diaphragm to shrink and melt, and spontaneous heat generation such as positive and negative active material analysis The reaction caused the lithium battery to catch fire and explode. The thermal runaway of lithium batteries seriously threatens the safety of users’ lives and property. Therefore, the research on the mechanism of thermal runaway is particularly important. In the past, due to the limitation of test conditions, we could only indirectly through the changes in case temperature and battery voltage. Infer some reactions inside the lithium battery. In essence, thermal runaway is a positive energy feedback cycle: increased temperature will cause the system to heat up, and the system will heat up and increase the temperature, which in turn makes the system hotter. Thermal runaway is a very common phenomenon. From concrete curing to star explosion, thermal runaway may occur. The phenomenon of thermal runaway and its intensity are related to the size, configuration and number of battery cells of the lithium battery. A small lithium battery pack has only a few lithium battery cells, so the chance of thermal runaway spreading from the problematic battery cell to other cells is relatively low. The huge battery packs of the Boeing 787 are another matter: they are housed in a sealed metal box and cannot emit waste heat. When a battery cell is hot enough to ignite the electrolyte, the remaining battery cells will quickly follow up. When a lithium battery is charged, the surface deposits of metallic lithium are very easy to coalesce into branched lithium dendrites, which pierce the diaphragm and cause a straight short circuit between the positive and negative electrodes. Moreover, metallic lithium is very active and can react directly with the electrolyte to generate heat, and its melting point is very low. Even if the surface metallic lithium dendrites do not pierce the diaphragm, as long as the temperature is slightly higher, the metallic lithium will dissolve and cause a short circuit. The higher the temperature at which the material undergoes the redox thermal reaction, the weaker its oxidizing ability is declared. The stronger the oxidizing ability of the positive electrode material, the more violent the reaction will occur, and the easier it is to cause safety accidents. 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: What are the advantages of using lithium iron phosphate battery packs in energy storage power stations