Why do lithium-ion batteries bulge?
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 stump crystals, resulting in battery swelling.
2. 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 causes reversible damage to the SEI film, leading to the collapse of the negative electrode material and resulting in lithium-ion battery bulging.
If the charger used is not up to standard, it may cause the battery to bulge, or even lead to a safety accident or explosion.
3. Manufacturing process issues
The problem lies in the manufacturing quality of lithium-ion battery packs, including uneven electrode coatings and a relatively rough production process.
These three factors cause a violent reaction, similar to a short circuit, to occur inside the lithium-ion battery pack during use, generating a large amount of heat, which in turn leads to the decomposition and vaporization of the electrolyte, causing the battery to swell.
A friendly reminder: bulging lithium-ion batteries are a precursor to serious problems and should not be used further. Continuing to use them could lead to unimaginable consequences such as short circuits, overheating, smoke, and even combustion.
Can a bulging lithium-ion battery still be used?
It is not recommended to reuse a bulging lithium-ion battery. During the bulging process, the capacity of the lithium-ion battery pack has decreased, and the standby time is significantly shortened. In severe cases, the standby time may be extremely short, or the battery may even be unable to make calls, or it may restart upon making a call. In this case, the battery generally needs to be replaced, and for safety, it is best to buy a new battery.
When a lithium-ion battery pack bulges, it's best not to continue using the problematic battery. Because the cells have expanded, and if the expansion reaches a certain limit, it could potentially cause an explosion, which is extremely dangerous. For your own safety, it's best to replace the lithium-ion battery pack as soon as you notice bulging. This bulging is often caused by poor lithium-ion battery quality or excessively long charging times. A bulging battery should not be used; replace it with a new battery immediately.
