1. Internal short circuit (mostly soft package large monomer): the structure or process defects lead to the insertion of pole ears, too little surplus of diaphragm wrapping, burrs, diaphragm folding, etc. The insertion of the lug often occurs in the structure of thick batteries and parallel connection. The insulation of the lug position is not in place, and it is easy to cause internal acute short circuit in the subsequent finished products or use process, which may lead to combustion or explosion (internal short circuit: I have a deep understanding of this, and more than 2K of this type of battery was scrapped at that time, which actually belongs to the abnormal design defect. The essence is: internal acute short circuit). However, this situation is almost rare now, Except for external factors.

2. External short circuit: The explosion after burning caused by external short circuit of battery below 1AH is rare. Usually, the explosion is caused by bulging or simply burning off the lug. Personal analysis shows that the combustion is caused by external short circuit of power lithium battery or large capacity mobile phone battery. This involves that the customer does not consider the lug insulation when using the improperly installed metal outer box, and the battery smokes and burns abnormally at the installation site; It is also common for power lithium batteries to have inadequate structural fixing measures (improper consideration). The battery pack shakes during user use, causing damage to the external insulation protective film of the battery or damage to the connecting wire skin, which ultimately leads to short circuit combustion.

3. Overcharge explosion: This is the most dangerous and the company is most afraid of, but it still happens occasionally. From the understanding, there are two points: a. The user does not use the matching charger as required, thus damaging the protection line. The user often charges for unlimited time, which is difficult to avoid explosion; b. The battery configuration is unreasonable and the protection board fails. In this case, it will explode in a mess... The same goes for a single battery. 4. The above three points are relatively common. To sum up, comprehensive structural design and users' use according to the specifications are important directions to prevent product combustion or explosion. I believe that major battery cell manufacturers have already taken reasonable improvement measures. I think that developing more safe materials is the king's way to achieve lithium battery safety.