There may be two basic reasons for the expansion of lithium-ion batteries. The first reason is the level of production technology of polymer lithium-ion batteries: the metal electrode coating is not uniform and the processing technology is relatively rough. Another reason may be the problem of overcharging and overdischarging.
Li-ion battery bulge reasons:
1. Bulge caused by overcharge
Overcharging will cause all the lithium atoms in the positive electrode material to run into the negative electrode material, causing the originally full grid of the positive electrode to deform and collapse, which is also an important reason for the decline in the power of the lithium-ion battery. In this process, there are more and more lithium ions in the negative electrode, and the excessive accumulation makes the lithium atoms grow out of the tree stump crystals, which makes the lithium ion battery swell.
2. Bulge caused by over discharge
During the first charge and discharge of the 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 film 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, so this passivation film is called a solid electrolyte interface film , Referred to as SEI.
The SEI film has a protective effect on the negative electrode material, so that the material structure is not easy to collapse, and can increase the cycle life of the electrode material. The SEI film is not static, there will be a little change during the charging and discharging process, mainly part of the organic matter will undergo reversible changes. After the lithium ion battery is over-discharged, the SEI film is reversibly broken, and the SEI that protects the negative electrode material collapses after the destruction of the negative electrode material, thereby forming a bulging phenomenon.
3. The production level of lithium-ion batteries is problematic, the electrode coating is not uniform, and the production process is relatively rough.
4. The violent reaction of the short circuit generates a lot of heat, which causes the electrolyte to decompose and vaporize, and the battery bulges.
5. If you have a lot of lithium-ion batteries that are bulging, it is possible that the voltage of your commonly used battery charger does not match the lithium-ion battery, and it is recommended to replace it. In addition, if the lithium-ion battery is not used for a long time, there will be a problem of bulging.
So how to deal with the bulging lithium-ion battery?
Bulging lithium-ion battery packs will affect its use. It cannot be put into mobile phones or digital cameras. In addition, the presence of gas between the battery plates will also affect the charging and discharging capacity of the battery. Lithium-ion batteries have strict requirements on the charger and cannot be used at will. Connect the power supply and charge it carelessly. You must use a special charger for lithium-ion batteries. If the charger used does not meet the requirements, the battery will swell at the slightest level, and a safety accident or even an explosion may occur. The swollen lithium-ion battery must not be used anymore and can only be scrapped.
The bulging lithium battery can be directly discarded, because the power capacity is already very small, and there is no power after a short circuit. Lithium-ion batteries generally require professional recycling to avoid pollution.
So remind everyone that the bulging of the lithium-ion battery is a precursor to a major problem, and it is not recommended to use it. It may be short-circuit, heat, smoke, burning and other unimaginable consequences if it is used again.