Briefly describe the reason for the combustion and explosion of 18650 lithium battery

Reasons for burning or exploding of 18650 lithium battery 1. Internal short circuit: structural or technological defects lead to the insertion of the tabs, the excess of the diaphragm package is too small, burrs, and the diaphragm discount, etc. In the current structure with thick batteries and internal parallel connection, the tabs are inserted into the tabs. The insulation of the tabs is not in place. Adding a protective plate to the subsequent product or using the process will easily cause an internal acute short circuit and cause burning or explosion. However, this situation is almost always Less, unless external factors. 2. External short circuit: Lithium batteries below 1 AH are caused by external short circuits and explosions after combustion are rare. Usually they are swollen or simply burned off the tabs. Personally decomposed is the external short circuit of power lithium ion batteries or large-capacity mobile phone batteries. Resulted burning. This involves customers improperly installing the metal outer box without considering the insulation of the tabs, and abnormal battery smoking and burning occurred at the installation site; the power lithium-ion battery also often has insufficient structural fixing measures (not thoughtful), and the battery pack is used during the user’s use. Shaking may cause damage to the battery's external insulating protective film or damage to the connecting wire, which will eventually cause short-circuit and burn. 3. Overcharge explosion: This is the most dangerous and the one that the company fears most, but it still happens occasionally. From what we know, there are two points: a. The user does not use the matching charger as required, which destroys the protection circuit and the user often charges for an unlimited time. In this case, it is difficult to not explode; b. 18650 lithium battery The unreasonable configuration and the failure of the protective plate will cause a mess in this case. The same is true for a single battery. 4. When the 18650 lithium battery is heated, the reactions inside the battery are like a reaction chain, and each reaction promotes each other and proceeds in sequence. First, SEI film analysis heats up the battery, which promotes the reaction between the negative electrode and the solvent to release more heat, leading to the reaction between the negative electrode and the binder, solvent analysis, and then the positive electrode to start the thermal analysis reaction, releasing a lot of heat and gas. , Finally causing the lithium battery to burn or explode. 5. Manufacturing process. The manufacturing process of the 18650 lithium battery is also an important factor that affects the safety performance of the battery. The most important factors are three factors, namely the positive and negative electrode capacity ratio, slurry average degree control, and coating quality control. 6. Temperature. There are many factors that affect the safety of lithium batteries. Among them, battery materials have a major impact on the safety of lithium batteries, because battery materials generally have thermal activity. When the temperature of the battery continues to rise, many thermal reactions will occur inside it. When the heat cannot be dissipated in time, it is easy to cause battery safety accidents. Therefore, the choice of lithium battery positive and negative materials has an important impact on battery safety performance. 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: The difference between 21700 and 18650 lithium batteries