Important Processes of Making Pouch Cell

Whether in the digital or power application market, pouch cells have become a very important technical battery solution.

After formed an aluminum case with the battery case forming machine, there comes the important steps for the pouch cell.

1. Electrolyte injection and pre sealing process

After the pouch cell case is sealed at the top and side, it is necessary to conduct X-ray to check the parallelism of its winding core, and then removing water and gas in the glove box. When the drying room is standing for a certain time, it comes the electrolyte injection and pre sealing process.

When the top and side sealing of the cell is completed, there is only one opening on the side of the pouch cell, which is used for electrolyte injection. After the completion of injection, it is necessary to pre seal the side of the pouch, also known as pre seal. After a package is completed, theoretically the interior of the cell is completely isolated from the external environment.

2. Standing, chemical forming, case shaping

The purpose of formation is to form a stable SEI film on the electrode surface, which is equivalent to a process of "activating" the cell. In this process, a certain amount of gas will be generated, which is why the pouch cell should be reserved for the aluminum-plastic film. In some factories, the process will use clamps, that is, the cells will be clamped in the clamps and then put into the cabinet, so that the generated gas will be fully squeezed into the nearby air bag, and the electrode interface will be better after the formation.

After formation, some cells, especially thick cells, may be deformed due to large internal stress. Therefore, some factories will set up a shaping process after the formation with a battery cell shaping machine.

3. Secondary sealing process

Gas will be produced during the formation process, so we need to extract the gas and then continue the second sealing. During the second sealing, firstly, the air bag is punctured by the guillotine and vacuumized at the same time, so that the gas in the air bag and a small part of the electrolyte will be extracted. Then the second sealing head is immediately sealed in the second sealing area to ensure the air tightness of the electric cell. Finally, cut the air bag of the encapsulated cell, and a pouch cell is basically formed.

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