The top sealing process is the most difficult process to control in the entire package. The main difficulties include：
1) Align the packaging aluminum foil (cut, fold in half)；
2) Control of TAB position (cell width, center distance, margin)；
3) Battery feeding positioning (battery unsealed area)；
4) Heat sealing head structure design (head width, stopper, head groove depth)；
5) Optimization of heat sealing process conditions (time, temperature, pressure, etc.).
Side sealing: It is the encapsulation of the battery after the top sealing is completed. The process is mainly to optimize the heat sealing process conditions and cell position.
The purpose is to prevent the corners sealed in the folded corners of the packaging aluminum foil from being damaged.
The requirement for corner sealing is only to fuse the two layers of packaging aluminum foil together. The aim is to prevent stress concentration caused by bending. Surely, the process controlling is mainly to the optimization of battery cell positioning and heat sealing process conditions.
The purpose is to seal the air bag after liquid injection. The aim is to prevent electrolyte from leaking and keep water vapor outside.
The requirement of vacuum packaging is only sealing. For the same, the process controlling is mainly to the optimization of battery cell positioning and heat sealing process conditions.
Secondary encapsulation (Degassing):
It is the process of venting and sealing the formed battery cells.
Compared with the side seal, it is required to pierce and encapsulate the air bag under vacuum conditions.