What are the reasons for the fire of lithium batteries?

In daily life, lithium batteries can be seen almost everywhere, from electric vehicles to computer motherboard batteries. Lithium batteries have become an indispensable part of people. We often see various safety accidents caused by lithium batteries. The most impressive thing is the explosion and fire of lithium batteries. Then the common causes of fire in lithium batteries are mainly as follows. 1 Insufficient negative electrode capacity. When the negative electrode part opposite the positive electrode part has insufficient capacity or no capacity at all, part or all of the lithium that appears during charging cannot be inserted into the interlayer structure of the negative electrode graphite, and will be deposited on the surface of the negative electrode. Protruding dendrites, and the next charging, this protruding part is more likely to cause lithium precipitation. After tens to hundreds of cycles of charging and discharging, the dendrites will grow up, and finally pierce the diaphragm paper, causing internal short circuits. . The battery core discharges rapidly, and a large amount of heat occurs, which burns the diaphragm and causes a greater short circuit. The high temperature will decompose the electrolyte into gas, and the negative carbon and diaphragm paper will burn, resulting in excessive internal pressure. When subjected to this pressure, the battery cell will explode. 2 The moisture content is too high. Moisture can react with the electrolyte in the battery cell and process gas. When charging, it can react with the generated lithium to generate lithium oxide, which causes the capacity of the battery cell to be lost, and it is easy to overcharge the battery to generate gas. , The decomposition voltage of water is low, and it is easy to decompose to generate gas when charging. When this series of generated gas will increase the internal pressure of the battery, when the shell of the battery cannot withstand it, the battery will explode. 3 Internal short circuit Due to the internal short circuit phenomenon, the battery core discharges with a large current, and a large amount of heat occurs, which burns the diaphragm and causes a greater short circuit phenomenon. In this way, the battery core will have a high temperature, causing the electrolyte to decompose into gas, causing internal pressure. If it is too large, when the shell of the battery cell cannot withstand this pressure, the battery cell will explode. 4 When the overcharge core is overcharged, the excessive release of lithium in the positive electrode will change the structure of the positive electrode. If too much lithium is released, it is easy to be unable to be inserted into the negative electrode, and it is also easy to cause lithium deposition on the surface of the negative electrode. Moreover, when the voltage reaches 4.5V or more At this time, the electrolyte will decompose and process a large amount of gas. All of the above may cause an explosion. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete it.