▲Laser welding battery cell accessories samples

3. Other difficulties

Soft-packed tab welding requires high welding tooling. The tabs must be pressed firmly to ensure the welding gap. It can realize high-speed welding of complex trajectories such as S-shaped and spiral shapes, increasing the joint area of the weld and strengthening the welding strength.

The welding of cylindrical battery cores is mainly used for the welding of the positive electrode. Since the shell of the negative electrode is thin, it is very easy to weld through. For example, some manufacturers currently use a welding-free process for the negative electrode, while the positive electrode uses laser welding.

When the square battery combination is welded, the poles or connecting pieces are thickly contaminated. When welding the connecting pieces, the pollutants decompose and easily form welding explosion points, causing holes. Batteries with thin poles and plastic or ceramic structural parts underneath are easy to weld. Wear. When the pole is small, it is easy to weld to the point that the plastic is burned, forming an explosion point. Do not use multi-layer connecting sheets. There are holes between the layers and it is difficult to weld firmly.

▲One of the battery core components that requires laser welding

The most important process of the welding process of square batteries is the packaging of the shell cover, which is divided into the welding of the top cover and the bottom cover according to the different positions. Because the batteries they produce are small in size, some battery manufacturers use a "deep drawing" process to manufacture battery cases, and only need to weld the top cover.

The welding methods of square batteries are mainly divided into side welding and top welding. The main benefit of side welding is that it has less impact on the inside of the battery core and spatter will not easily enter the inside of the shell cover. Since bulges may occur after welding, which will have a slight impact on the assembly of subsequent processes, the side welding process has extremely high requirements on the stability of the laser and the cleanliness of the material. Since the top welding process is welded on one surface, it has relatively low requirements for the integration of welding equipment and is simple for mass production. However, it also has two disadvantages. One is that a little spatter may enter the battery core during welding, and the other is the front section of the casing. High processing requirements can lead to cost issues.