Safety knowledge and explosion types of explosion-proof lithium batteries

The types of battery cell explosion can be summarized as external short circuit, internal short circuit and overcharge. The exterior of the battery refers to the exterior of the battery cell, including short circuits caused by poor insulation design of the battery pack. When a short circuit occurs outside the iron core and the electronic components cannot cut off the circuit, high heat will appear inside the iron core, causing part of the electrolyte to vaporize and the battery casing to enlarge. When the internal temperature of the battery reaches 135°C, the micropores are closed, the electrochemical reaction is terminated or almost terminated, the current drops, the temperature drops slowly, and an explosion is guarded. However, if the thin hole sealing rate is too low, or the pores on the diaphragm paper are not closed at all, the battery temperature will continue to rise, more electrolyte will evaporate, and the battery case will eventually be blocked. Even if the battery temperature is increased and the material burns and explodes, the internal short circuit is mainly due to the burr of the copper foil and aluminum platinum passing through the diaphragm, or the lithium atom network crystal passing through the diaphragm. These tiny fibrous metals can cause short circuits. Because the needle is very thin and has a certain resistance value, the current is not necessarily large. Burrs on copper and aluminum foils are caused by excessive processing. The observed phenomenon is that the battery leakage rate is too fast, most of which can be screened by the core factory or the wiring harness processing factory. Moreover, due to the small burrs, they will sometimes burn off, returning the battery to normal. Therefore, the probability of an explosion caused by a small short circuit of the burr is not high. Such a view can start from the core plant. Often batteries with a voltage difference will appear soon after charging, but there are few explosion accidents, which is supported by statistics. Therefore, the explosion caused by the internal short circuit is mainly caused by overcharge. Because the electrode chip is full of needle-shaped lithium crystals, the puncture points are everywhere, and the micro short circuits are everywhere. As a result, the battery temperature will gradually rise, and eventually electrolyte gas will appear at a high temperature. In this case, whether the material burns and explodes when the temperature is too high, or the shell is first supported, air enters, and the metal lithium is strongly oxidized, that is, the end of the explosion. However, such an explosion caused by an internal short circuit caused by charging does not necessarily occur during charging. It is possible that when the battery temperature is not enough to burn the material and the gas generated is not enough to damage the battery casing, the consumer terminates the charging and takes out the mobile phone. At this time, the heat generated by many micro-short circuits slowly increases the temperature of the battery, and after a period of time, an explosion occurs. The general description for consumers is that when picking up the phone, the phone is found to be hot and explodes after being thrown away. Based on the above types of explosions, we can focus on preventing overcharging and external short circuits, and improving the safety of the core. Anti-overcharge and anti-external short circuit belong to electronic protection, which is closely related to battery system design and battery assembly. Chemical and mechanical protection is the key to improving battery safety and is closely related to battery processing manufacturers. 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 article: What is an iron battery? Analysis of the advantages of iron batteries