What is the battery SEI film? -Lithium - Ion Battery Equipment
What is the lithium -ion battery SEI film? The formation of lithium -ion battery SEI film. The SEI density of lithium-ion batteries is very good and low in impedance at -20 ℃. The thickness of the SEI is about 100-120nm. , LICO2-R, alcohol salt, and non-conductive polymer composition are multi-layered structures. The side of the electrolyte is porous, and the side of the electrode is dense.
What is the lithium -ion battery SEI film?
During the first charging and discharge of liquid lithium -ion batteries, the electrode material and electrolyte react on the solid -liquid phase interface to form a layer of passivation layer covered with the surface of the electrode material. This kind of passivation layer is a kind of interface layer, which has the characteristics of solid electrolyte. It is an excellent conductor of electronic insulators but LI+. Li+can be freely embedded and removed by the passivation layer. Therefore Solid electrolytic interface mask ", referred to as SEI film for short.
The formation of SEI membrane has a vital impact on the performance of the electrode material. On the one hand, the formation of the SEI membrane consumes part of the lithium ions, so that the first charge and discharge irreversible capacity will be added, which reduces the charge and discharge efficiency of the electrode material; And the solvent molecules cannot pass the passivation film through this layer, which can effectively prevent the co -embedded of the solvents and prevent the destruction of the electrode material caused by the embedded of the electrode material, which greatly improves the circulating performance and service life of the electrode.(Lithium - Ion Battery Equipment)
The formation of the SEI membrane is the process of electrical chemistry reaction. When the voltage reaches a certain value, a series of physical chemical changes will occur on the negative surface. In actual production, it is important to form a membrane into this step. The SEI film is important consisting of alkyl lithium lithium, lithium carbonate, etc. It has a multi -layer structure. The end of the electrolyte is more dense. In the middle as the middle phase, it has the nature of solid electrolytes, and only allows lithium ions to pass through, and electronic insulation.
Lithium -ion battery SEI film use is as follows
First, the SEI membrane will protect the use of negative materials, making the material structure difficult to collapse, and the circulating life of new electrode materials.
Second, the SEI membrane consumes a part of lithium ions during the occurrence process, and the negative reaction process is actually a process of lithium ion embedding and out of the carbon layer structure. Therefore, the formation of the SEI membrane will reduce the first cycle efficiency of the negative electrode.
Third, the SEI film is not only produced on the negative surface, but also appears on the surface of the positive electrode, but the impact is relatively small.
In addition, the first cycle efficiency is a very important performance indicator of the negative electrode material. The higher the efficiency, the better the first efficiency. Through the method of covering, ballization, and surface modification of negative materials, the first cycle efficiency and cycle life can be greatly added.
The formation mechanism of lithium ion battery SEI film
位 Under a certain negative electrode potential, the lithium ion in the electrode/electrolyte interface and the solvent molecules in the electrolytes occur irreversible reactions;
⑵ Incantvant response important occurring in the first charging process of the battery;
(3) After the electrode surface is completely covered by the SEI membrane, the irreversible reaction stops;
Once 定 Once a stable SEI film is formed, the charging and discharge process can be carried out multiple times.
The formation of the SEI membrane will consume lithium ions in the battery, and the SEI membrane is not stable. It will continue to rupture during the cycle. The new carbon surface will be exposed. Continuous lithium ions and electrolytes are constantly consuming, resulting in a decrease in the capacity of the battery.
What is the lithium -ion battery SEI film?
During the first charging and discharge of liquid lithium -ion batteries, the electrode material and electrolyte react on the solid -liquid phase interface to form a layer of passivation layer covered with the surface of the electrode material. This kind of passivation layer is a kind of interface layer, which has the characteristics of solid electrolyte. It is an excellent conductor of electronic insulators but LI+. Li+can be freely embedded and removed by the passivation layer. Therefore Solid electrolytic interface mask ", referred to as SEI film for short.
The formation of SEI membrane has a vital impact on the performance of the electrode material. On the one hand, the formation of the SEI membrane consumes part of the lithium ions, so that the first charge and discharge irreversible capacity will be added, which reduces the charge and discharge efficiency of the electrode material; And the solvent molecules cannot pass the passivation film through this layer, which can effectively prevent the co -embedded of the solvents and prevent the destruction of the electrode material caused by the embedded of the electrode material, which greatly improves the circulating performance and service life of the electrode.(Lithium - Ion Battery Equipment)
The formation of the SEI membrane is the process of electrical chemistry reaction. When the voltage reaches a certain value, a series of physical chemical changes will occur on the negative surface. In actual production, it is important to form a membrane into this step. The SEI film is important consisting of alkyl lithium lithium, lithium carbonate, etc. It has a multi -layer structure. The end of the electrolyte is more dense. In the middle as the middle phase, it has the nature of solid electrolytes, and only allows lithium ions to pass through, and electronic insulation.
Lithium -ion battery SEI film use is as follows
First, the SEI membrane will protect the use of negative materials, making the material structure difficult to collapse, and the circulating life of new electrode materials.
Second, the SEI membrane consumes a part of lithium ions during the occurrence process, and the negative reaction process is actually a process of lithium ion embedding and out of the carbon layer structure. Therefore, the formation of the SEI membrane will reduce the first cycle efficiency of the negative electrode.
Third, the SEI film is not only produced on the negative surface, but also appears on the surface of the positive electrode, but the impact is relatively small.
In addition, the first cycle efficiency is a very important performance indicator of the negative electrode material. The higher the efficiency, the better the first efficiency. Through the method of covering, ballization, and surface modification of negative materials, the first cycle efficiency and cycle life can be greatly added.
The formation mechanism of lithium ion battery SEI film
位 Under a certain negative electrode potential, the lithium ion in the electrode/electrolyte interface and the solvent molecules in the electrolytes occur irreversible reactions;
⑵ Incantvant response important occurring in the first charging process of the battery;
(3) After the electrode surface is completely covered by the SEI membrane, the irreversible reaction stops;
Once 定 Once a stable SEI film is formed, the charging and discharge process can be carried out multiple times.
The formation of the SEI membrane will consume lithium ions in the battery, and the SEI membrane is not stable. It will continue to rupture during the cycle. The new carbon surface will be exposed. Continuous lithium ions and electrolytes are constantly consuming, resulting in a decrease in the capacity of the battery.
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