Assembly process and method of soft-packed lithium iron phosphate battery
Aluminum plastic film forming process
The soft-packed lithium iron phosphate battery cell can be designed in different sizes according to the needs of customers. When the external dimensions are designed, the corresponding mold must be opened to form the aluminum plastic film. Generally, the single hole is selected when the battery is thin, and the double hole is selected when the battery is thick, because too much deformation on one side will break the deformation limit of the aluminum-plastic film and cause rupture.
Top side sealing process
The top-side sealing process is the first packaging process of the soft-packed lithium iron phosphate battery. The top side seal actually includes two processes, the top seal and the side seal. First, put the wound core into the punched pit, and then fold the packaging film in half along the dotted line. The top seal is to seal the tab, which is made of metal. After formation, some cells, especially thick cells, may be deformed due to large internal stress. Therefore, some factories will set up a fixture shaping process after the formation, also called fixture baking (baking). After the second air bag is cut, the edges should be trimmed and folded, that is, the one edge and the second edge are cut to the appropriate width, and then folded to ensure that the width of the battery does not exceed the standard. After folding, the battery cell can be installed in the capacity-dividing cabinet for capacity distribution. In fact, it is a capacity test to see if the capacity of the battery core reaches the specified minimum value. In principle, all batteries must be tested before leaving the factory to ensure that batteries with unqualified capacity will not be delivered to customers. However, when the battery production volume is large, some companies will perform partial capacity division and use statistical probability to judge the pass rate of the batch of battery capacity.
After the capacity is divided, the cells with qualified capacity will enter the subsequent processes, including appearance inspection, yellow glue, edge voltage detection, tab transfer welding, etc. Several processes can be added or removed according to customer needs. The last is OQC inspection, and then packaged and shipped.
Note that up to this point, they are only batteries. The cells will be sent to the Pack factory for further processing, including welding circuit boards, packaging and so on. Downstream of the Pack factory are various manufacturers, such as Apple, Lenovo, and Huawei. They will take the battery pack and install it in the terminal before it comes to our consumers.