(1) Manufacturing level
Lithium-ion battery bloating may be the manufacturing level of lithium iron phosphate battery packs, the electrode coating is not uniform, and the production process is relatively rough.
(2) Lithium ion battery bulging caused by overcharging
Overcharging causes all the lithium atoms in the positive electrode material to run into the negative electrode material, resulting in deformation and collapse of the original positive electrode full grid, which is also an important reason for the decline in battery power of lithium iron phosphate batteries. In this process, more and more lithium ions are deposited in the negative electrode, causing lithium atoms to grow into stumps and crystallize, resulting in battery pack expansion.
In the first charge and discharge process of the liquid lithium ion battery, the electrode material reacts with the electrolyte at the solid-liquid interface to form a passivation layer covering the surface of the electrode material. The passivation layer formed can effectively prevent the passage of electrolyte molecules, while Li+ can be freely embedded in and leached out of the passivation layer, which has the characteristics of a solid electrolyte. Therefore, this passivation layer is called SEI, and the SEI film is not static. During the charging and discharging process, there will be some changes, importantly, reversible changes in organic matter. The SEI film is reversibly damaged in lithium iron phosphate ion battery packs after over-discharge. After the SEI that protects the anode material is destroyed, the anode material will collapse, resulting in the formation of a bulge.
(4) A large amount of heat will occur from the violent reaction of the short circuit, causing the electrolyte to decompose and evaporate, causing the battery to swell.
(5) The reason for the low quality of the lithium iron phosphate ion battery charger. The charger is made of low quality circuit boards, innovative or low quality components. Due to inaccurate heating and parameter drift, the charging voltage limit is out of control, leading to the internal gas kneading and deformation of lithium-ion batteries, resulting in cracking or even bursting of the battery shell.
(6) Lithium iron phosphate battery packs for long-term use will also appear puffy phenomenon, because the air has a certain degree of conductivity, so, put too long is equivalent to the battery positive and negative poles in direct contact, a slow short circuit.