1, overcharging lithium battery bulging
Overcharging will lead to all the lithium atoms in the positive electrode material to run into the negative electrode material, resulting in deformation and collapse of the positive electrode originally full grid, which is a major reason for the decline in the power of the lithium iron phosphate battery pack. In this process, the negative electrode lithium ions more and more, excessive accumulation of lithium atoms grow stump crystallization, making the lithium battery pack bulging.
2, over-discharge caused by the bulge
In the liquid lithium-ion battery first charge and discharge process, the electrode material and electrolyte in the solid-liquid phase interface reaction, the formation of a layer of passivation covering the surface of the electrode material.
The passivation layer effectively prevents the passage of electrolyte molecules, but Li+ can be freely embedded and dislodged through the passivation layer, which has the characteristics of a solid electrolyte, and therefore this passivation layer is called SEI. SEI film is not static, and there will be a small change in the charging and discharging process, mainly due to the fact that some of the organic matter will undergo reversible changes.
Lithium iron phosphate battery pack over-discharge makes the SEI membrane reversible ring, protect the negative electrode material SEI damage makes the negative electrode material collapse, thus forming a bulging bag phenomenon.
3, manufacturing level
Lithium battery bulging may be the lithium iron phosphate battery pack manufacturing level of the problem, the electrode coating is not uniform, the production process is relatively rough.
4, lithium iron phosphate battery packs for a long time without using the phenomenon of bulging will also occur, because the air is conductive to a certain extent, therefore, put too long is equivalent to the battery's positive and negative electrodes are in direct contact, for a chronic short circuit.
Expanded information:
Lithium iron phosphate batteries are mainly used in the following areas:
1, large-scale electric vehicles: buses, electric cars, attractions tour buses and hybrid vehicles, etc.;
2, light electric vehicles: electric bicycles, golf carts, small flatbed vehicles. bicycles, golf carts, small flat battery cars, forklifts, cleaning trucks, electric wheelchairs, etc.;
3, electric tools: drills, saws, lawnmowers, etc.;
4, remote-controlled cars, boats, airplanes and other toys;
5, solar and wind power energy storage equipment;
6, UPS and emergency lights, warning lights and mining lamps (the best safety
7, alternative camera 3V disposable lithium batteries and 9V nickel-cadmium or nickel-metal hydride rechargeable batteries (identical size);
8, small medical equipment and portable instruments.
Baidu Encyclopedia - Lithium Iron Phosphate Battery