Lithium iron phosphate battery bulge is mainly caused by four major factors.
1, the lithium-ion battery bulge caused by overcharging
Overcharging will lead to lithium atoms in the positive material all run to the negative material inside, resulting in the original full grid of the positive pole deformation collapse, which is also an important reason for the drop in power of lithium iron phosphate battery pack. In this process, the negative electrode lithium ions more and more, excessive accumulation makes lithium atoms grow stump crystals, making the lithium-ion battery pack bulge.
2、Bulging caused by over-discharge
During the first charge and discharge of liquid lithium-ion battery, the electrode material reacts with the electrolyte at the solid-liquid phase interface to form a passivation layer covering the surface of the electrode material. The formed passivation layer film can effectively prevent the passage of electrolyte molecules, but Li+ can freely embed and detach through this passivation layer, which has the characteristics of a solid electrolyte, so this passivation film is called SEI.
The SEI film is not immutable and will change a little during charge and discharge, and importantly, some of the organic matter will change reversibly. Lithium iron phosphate ion battery pack after excessive discharge makes the SEI film reversible broken ring, the SEI to protect the negative electrode material after the destruction of the negative electrode material collapse, thus forming a bulge phenomenon.
3, manufacturing level problems
Lithium-ion battery bulge may be lithium iron phosphate battery pack manufacturing level problems, electrode coating is not uniform, the production process is relatively rough.
4, not used for a long time
Long time without use will also occur bulging phenomenon, because the air is to some extent conductive, therefore, put too long is equivalent to direct contact between the positive and negative electrodes of the battery, a chronic short circuit.
