1. Overcharging can easily lead to bulging of lithium batteries.
Overcharging will cause all the lithium atoms in the positive electrode material to flow into the negative electrode material, causing the original full grid of the positive electrode to deform and collapse. This is also an important reason for the decrease in battery capacity of lithium-ion batteries. During this process, there are more and more lithium ions in the negative electrode. The excessive accumulation causes the lithium atoms to grow into stump crystals, causing the lithium-ion battery to bulge.
2: Over-discharge can easily cause lithium battery bulging.
During the first charge and discharge process of a 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 layer can effectively prevent the passage of electrolyte molecules, but Li+ can be freely inserted and extracted through the passivation layer, which has the characteristics of a solid electrolyte. Therefore, this passivation film is called SEI.
The SEI film is not static and will undergo slight changes during the charge and discharge process. The important thing is that some organic matter will undergo reversible changes. Over-discharge of lithium-ion battery bulges causes reversible damage to the SEI film. The destruction of the SEI that protects the negative electrode material causes the negative electrode material to collapse, thus forming a bulging phenomenon.
Three: Lithium batteries with substandard quality are prone to bulges
The bulge of lithium-ion battery may be caused by the manufacturing level of lithium-ion battery bulge. The electrode coating is uneven and the production process is rough.
Four: Lithium batteries are easy to bulge if they are not used for a long time.
Bulging will also occur if the battery is not used for a long time, because air is conductive to a certain extent. Therefore, leaving it for too long is equivalent to direct contact between the positive and negative electrodes of the battery, creating a chronic short circuit.