Reasons for lithium-ion battery swelling:
1. Bulging caused by overcharging
Overcharging causes all the lithium atoms in the positive electrode material to migrate into the negative electrode material, leading to the deformation and collapse of the originally full grid in the positive electrode. This is a major reason for the decrease in the capacity of lithium-ion battery packs. During this process, the number of lithium ions in the negative electrode increases, and excessive accumulation causes lithium atoms to grow into stumps and crystals, resulting in the swelling of the lithium-ion battery pack.
II. Bulging caused by over-discharge
The SEI film protects the negative electrode material, preventing structural collapse and extending cycle life. However, the SEI film is not static; it undergoes slight changes during charge and discharge, with some organic components experiencing reversible alterations. Over-discharge of a lithium-ion battery pack can cause reversible damage to the SEI film. This damage to the SEI, protecting the negative electrode material, leads to the collapse of the negative electrode material and the formation of bulges.
III. Charger
The charger parameters do not match the requirements of the lithium-ion battery pack. This may be because they were originally incompatible, or it may be due to parameter drift caused during use.
IV. Battery Sulfation
The main cause of battery sulfation is sulfation. The main causes of sulfation include high current discharge, inability to charge in time, deep discharge, frequent discharge, insufficient charging time, and factors caused by the charger itself.
