Brief analysis of explosion types of lithium-ion batteries

Analysis of lithium-ion battery explosion types There are three types of battery explosions: external short circuit, internal short circuit and overcharge. The external connection here refers to the outside of the battery, including short circuits due to poor internal insulation design of the battery pack. When a short circuit occurs on the outside of the battery and the electronic components cannot cut off the circuit, high heat will appear inside the battery, which will cause part of the electrolyte to evaporate and expand the battery casing. When the internal temperature of the battery reaches 135°C, the high-quality membrane paper will close the tiny holes, the electrochemical reaction will stop or nearly stop, the current will drop sharply, and the temperature will drop slowly to prevent explosion. However, the pore closing rate is very poor, or the pores are not closed by the diaphragm paper, which can make the battery temperature continue to rise, more electrolyte evaporates, and finally the battery shell ruptures, and even the temperature of the new battery makes the internal short circuit of the material. It is important because of combustion and explosion The copper foil and aluminum foil burr the diaphragm, the diaphragm or the atomic lithium dendrites are exhausted. These tiny needle-like metals can cause micro short circuits. Because the needle is very thin and has a certain resistance value, the current is not necessarily large. Copper foil burrs appear during the production process of copper foil. The phenomenon that can be observed is that the battery leaks too fast, most of which can be screened by the battery factory or assembly factory. Because the burr is so small, it sometimes burns off, returning the battery to normal. Therefore, the probability of an explosion caused by a burr short circuit is not high. This argument can be derived from the fact that after frequent charging in each battery factory, the low-voltage battery is broken, but it rarely explodes, which is supported by statistics. Therefore, the explosion caused by the internal short circuit is mainly caused by overcharge. Because there are needle-like lithium crystals everywhere on the charged electrode, and the piercing points are everywhere, there are short circuits everywhere. Therefore, the battery temperature will gradually increase, and finally high temperature will electrolyze gas. When the temperature is too high, either the material burns and explodes, or the shell explodes first, causing air to enter and violently oxidize with lithium. However, this kind of explosion caused by an internal short circuit caused by overcharging does not necessarily occur during charging. It is possible that consumers will stop charging and take out the phone before the battery heats up enough to burn and there is enough gas to burst the battery case. At this time, the heat generated by a large number of micro-short circuits slowly raises the temperature of the battery, and an explosion will occur after a period of time. Consumers usually describe picking up their phones, finding them hot, throwing them away, and exploding. According to the above explosion types, we can focus on preventing overcharging, preventing external short circuits, and improving battery safety. Among them, the prevention of overcharge and external short circuit belongs to electronic protection, which is closely related to the design of the battery system and the battery pack. Chemical and mechanical protection is the key to improving battery safety, which is closely related to battery 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: Classification and naming rules of lithium-ion batteries