2.3 Easy to fall off after welding

After the battery cells are welded, it is required that the welding ribbon and the main grid line of the battery cells should be welded firmly, and the welding ribbon should be pulled at an angle of 45° by hand to prevent it from falling off. But in reality, after welding is completed, if the welding ribbon is gently lifted by hand, the welding ribbon will fall off. There are mainly the following reasons for this phenomenon [3]:

1) The welding speed is too fast. During welding, if the welding iron tip slides over the welding ribbon too fast, it will cause incomplete melting of the welding ribbon, which will also affect the welding effect between the welding ribbon and the cell grid, causing the welding ribbon to fall off.

2) The pressure on the welding iron tip is too small. When the welding iron tip slides over the welding strip, a certain amount of pressure needs to be applied to the welding strip to promote the bonding between the welding strip and the cell grid. If the pressure is too small, the bonding force between the welding strip and the grid will be insufficient. It will cause it to fall off; conversely, excessive pressure will cause the battery piece to break. Therefore, during the welding process, the downward pressure exerted by the welding iron must be controlled.

If the welding ribbon is easy to fall off due to the above reasons, it can be solved in the following ways:

1) Reduce the welding speed. Slowly sliding the welding iron tip over the welding strip can fully melt the flux on the surface of the welding strip and the grid line, which can also improve the welding strength between the welding strip and the grid line.

2) Increase welding pressure. When welding, appropriately increase the pressure exerted by the welding iron tip on the welding strip to improve the bonding ability between the welding strip and the cell grid, thereby improving the welding effect.

In addition, it is easy to fall off after welding, which may also be caused by the insufficient temperature of the welding iron or heating pad. The causes and solutions are similar to the above-mentioned problem of the inability to weld the welding strips to the battery cells, and will not be described again here.

3. Conclusion

Poor welding of battery cells are caused by many reasons, including material, environmental factors, and human factors. Among them, the material itself is the biggest influencing factor, but the performance of the material is also greatly affected by the environment. Therefore, in order to ensure welding quality and reduce welding defects, welding materials must be stored strictly as required. Welding ribbons, battery cells, flux and other materials must be stored in a dry, normal temperature, closed environment to avoid moisture and oxidation. At the same time, during the welding process, strictly follow the specifications, correctly set the temperature of the welding iron and heating pad, and control the welding speed and pressure. In this way, the welding process of the battery cells can be successfully completed.