Decompose the cause of lithium battery explosion in detail

Lithium battery principle Lithium battery is mainly composed of positive electrode, negative electrode, separator and electrolyte. The positive and negative electrode layers are tightly rolled together. The layers are separated by insulators. The positive and negative electrodes are immersed in the electrolyte.. Below is a cylindrical battery. Take a square battery as an example. The positive and negative electrodes of the lithium battery are composed of two different lithium intercalation compounds. The positive electrode materials mainly include transition metal oxides, metal oxides, metal sulfides, etc.. Commercial lithium batteries Commonly used cathode materials are transition metal oxides. The most widely used anode materials are inorganic non-metallic materials, metal materials, metal-non-metal composite materials, metal oxides, etc.. Lithium iron phosphate anode and cathode materials are coated on conductive materials The electrode material that forms the electrode determines the voltage and capacity of the battery. As an important part of the lithium battery, the electrolyte plays an important role in the transmission of current during the charging and discharging of the battery. In order to prevent short-circuiting of the positive and negative materials immersed in the electrolyte due to mutual contact, the positive and negative materials are separated by a polyolefin separator. The lithium ion secondary battery is actually a battery with a poor lithium ion concentration.. When charging , Take out Li from the positive electrode and insert it into the negative electrode through the electrolyte. The negative electrode is in a lithium-rich state and the positive electrode is in a lithium-poor state. The electronic compensation charge is supplied to the carbon negative electrode by an external circuit to ensure the balance of charge. In relation to discharge, Li is removed from the negative electrode and inserted into the cathode material through the electrolyte. Under normal charge and discharge conditions, lithium ions are inserted and removed between the layered carbon material and the layered structure oxide, which usually only causes the change of the material layer spacing without destroying their crystal structure. During the charging and discharging process, the chemical structure of the negative electrode material is basically unchanged. The ionic reaction equation is increasingly impossible to add safety measures inside the battery, because it is now pursuing higher capacity to improve battery life. From the commercialization of lithium batteries in 1991 to the present, the power capacity of lithium batteries has increased four or five times the mechanism of lithium battery explosion. So we know how it works, so we can know what caused the explosion of lithium batteries.. The charging and discharging of lithium dendrite growth battery is the transfer of lithium ions back and forth. During the charging process, lithium ions are reduced to metallic lithium embedded in the negative electrode. Generally speaking, lithium will be embedded in the interlayer structure. However, due to the uncertainty of growth, lithium may grow on the surface of the electrode. The growth layer has a thorn-like structure like branches, which can damage the internal diaphragm of the battery and cause a short circuit inside the battery. And the battery exploded. If the battery is defective, the metal particles are connected to the positive and negative electrodes through the insulating layer of the battery, changing the direction of the current, and a large amount of heat appears, which degrades the internal materials, makes the chemical reaction out of control, releases more heat, and ignites the battery pack. Charging Our current battery has a protection system that feeds back the battery voltage at any time to prevent overcharging, which may cause damage to the battery protection system or battery charger during overcharging. When overcharging occurs, the lithium ions left in the cathode material Continue to be removed and embedded in the negative electrode material. If the maximum lithium embedded in the carbon negative electrode is reached, the excess lithium will be deposited on the negative electrode material in the form of lithium metal, which greatly reduces the stability performance of the battery. Even if the explosion is concerned with lithium batteries, not only the battery capacity is an area to be improved, but also the safety performance cannot be ignored. Now some battery manufacturers have very high safety standards and even have to test batteries. We know that when the nail penetrates the battery, it will directly connect the positive and negative poles, which will cause an internal short circuit. Gel electrolytes and polymer electrolytes are also under further exploration, especially the development of polymer electrolytes. There is no volatilization of liquid organic electrolyte in the battery, which greatly improves the safety of the battery. 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: Which one is more harmful to lithium batteries or lead-acid batteries?