Today, we will continue to talk about pouch assembly.
Until the entire step of finally packaging or folding bicell in an aluminum pouch and sending it to a formation process is referred to as a 'packaging' process. The packaging process is a most important process for cell performance quality and safety, and there are many things to discuss. However, we will focus on the characteristics of the main process, and if you need a detailed explanation, please send me a message personally.
The first process is bi-cell welding. The stacked bi-cells are welded to connect each aluminum foil and copper foil. The source of welding was developed largely with ultrasonic waves and laser, and some companies applied resistance welding, but it was difficult to ensure stable welding quality due to the nature of copper with very low resistance. In addition, as cell capacity increases as time goes by, the number of stacked bi-cells also increases, and in this case, where the welding quality degrades at an interface between foils, electrical resistance increases and quality deviations. Therefore, facility manufacturers have tested various jig fabrics to improve the quality of welding, and special know-how of some companies has developed.
The second process is outer lead tab welding. The structure and size of the lead tab differ depending on the structure and size of the cell. Lead tab shows that the physical properties of the material have a great influence on the quality of actual welding. And, the thickness and size of the tab are related to electrical resistance and cannot be easily changed due to the manufacture of the cell module. It is difficult to change the specifications that have been decided once because this can affect the cell manufacturer's perspective and the design and assembly quality of the cell-supplied customer. The company that manufactures the facility also presents various structures to secure quality, but it is true that it cannot be easily changed except for proven methods. In particular, due to the large welding area, the structure of the welding horn and the structure of the fixture and unit to fix it have been studied for a long time.
I will explain consecutively in the next chapter.
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