Why are lifepo4 lithium battery bulging

Posted by sere on November 12th, 2020

Reasons for bulging lifepo4 lithium battery:

1. Lithium battery bulge caused by overcharge

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, which is also a main reason for the decrease in the power of the lithium iron phosphate battery pack. In this process, there are more and more lithium ions in the negative electrode, and the excessive accumulation makes the lithium atoms grow out of the tree stump crystals, which makes the lithium battery pack swell.

2. Drum bag caused by over discharge

During the first charge and discharge of the 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, and 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 charging and discharging process, mainly part of the organic matter will undergo reversible changes. After the lithium iron phosphate battery pack is over-discharged, the SEI film will be reversibly broken, and the SEI protecting the negative electrode material will collapse after the destruction of the negative electrode material, thereby forming a bulging phenomenon.

3. Manufacturing level issues

The bulging of lithium batteries may be a problem of the manufacturing level of lithium iron phosphate battery packs. The electrode coating is uneven and the production process is relatively rough.

4.Lithium iron phosphate battery packs will bulge if they are not used for a long time

Because air is conductive to a certain extent, too long a long time is equivalent to direct contact between the positive and negative electrodes of the battery, causing a chronic short circuit.