1, scour pit
The soft lithium battery mentioned above is made of aluminum-plastic film, so the processing of aluminum-plastic film has become a technological process. Soft-pack lithium-ion batteries can be designed in different sizes according to customers' needs. When designing the dimensions, it is necessary to open the corresponding mold to make the aluminum-plastic film shape. This process is also called pit punching, that is, under the condition of heating, a pit is punched on the aluminum-plastic film that can hold the coil core with a molding die.
2. Top seal
Top side seal is divided into top seal and side seal. First, put the finished winding core into the punched pit, then fold the packaging film in half, put the whole aluminum-plastic film into the fixture, and seal the top edge in the top edge sealing machine. When packaging, both ends have a certain temperature (generally around 180℃). When it is closed, it is pressed on the aluminum-plastic film, and the PP layer of the aluminum-plastic film melts and sticks together, and the packaging is OK. Top sealing is to seal the ear piece, which can be done by a small part of ear piece glue. When packaging, the PP in the pull-tab adhesive and the PP layer of the aluminum-plastic film are fused and bonded to form an effective packaging structure. There is nothing to say about the side seal, which is similar to the top seal. After the battery cell is sealed on the top side, there is only one opening on the airbag side, which is related to the next operation.
3. Liquid injection and pre-sealing procedures
After the soft package battery core is sealed at the top and side, it is necessary to check the parallelism of its winding core with X-ray, and then enter the drying room to remove moisture. After the drying chamber is allowed to stand for a period of time, it enters the processes of liquid injection and pre-sealing. Who left the airbag opening in the process of sealing the top side of the battery cell? The opening is used for liquid injection. After the liquid injection is completed, the edge of the airbag needs to be pre-sealed immediately, which is also called sealing. Theoretically, after packaging, the battery cells are completely isolated from the external environment. A similar top side seal.
4, standing, forming and fixture shaping processes.
After the liquid injection sealing is completed, it is necessary to let the battery cells stand first, which can be divided into high temperature standing and normal temperature standing according to different processes. The purpose of standing is to make the injected electrolyte fully soak the pole piece. Then you can do it with batteries. Chenghua is charging the battery for the first time, but it will not be charged to the highest voltage used, and the charging current is also very small. The purpose of formation is to form a stable SEI film on the electrode surface, which is equivalent to a process of "activating" the battery. Some batteries, especially thick batteries, may be deformed due to large internal stress after formation. Therefore, some factories will set up a fixture molding process after molding, also called fixture baking.