Why does lithium iron phosphate battery swell?

1. Overcharging of the lithium-ion battery caused by overcharging will cause all the lithium atoms in the positive electrode material to run into the negative electrode material, causing the original full grid of the positive electrode to deform and collapse. This is also a decrease in the power of the lithium iron phosphate battery pack. important reason. In this process, there are more and more lithium ions in the negative electrode, and the excessive accumulation causes the lithium atoms to grow out of the tree stump crystals, which makes the lithium ion battery pack swell. 2. Bulging caused by over-discharge During the first charge and discharge of a liquid lithium ion battery, the electrode material and the electrolyte react at the solid-liquid interface to form a passivation layer covering the surface of the electrode material. The formed passivation film can effectively prevent the passage of electrolyte molecules, but Li+ can be freely inserted and extracted through the passivation layer, which has the characteristics of a solid electrolyte, so this passivation film is called SEI. The SEI film is not static, there will be a little change during the charge and discharge process, the important thing is that some organic matter will undergo reversible changes. The over-discharge of the lithium iron phosphate battery pack causes the SEI film to be reversibly broken, and the SEI protecting the negative electrode material collapses after the destruction of the negative electrode material, thereby forming a bulging phenomenon. 3. The problem of manufacturing level Li-ion battery bulge may be a problem of the manufacturing level of lithium iron phosphate battery pack, the electrode coating is not uniform, and the production process is relatively rough. 4. The bulging phenomenon will occur if the lithium iron phosphate battery pack is not used for a long time, because the air is conductive to a certain extent. Therefore, if the battery is left for too long, it is equivalent to direct contact between the positive and negative electrodes of the battery. Short circuit. 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: What are the methods for recycling waste electric vehicle batteries?