Let's take a look at how many methods are there for welding lithium batteries?

First of all, let's take a look at how many methods are there for welding lithium batteries?

1. Wave welding: essentially a combination of ultrasonic welding and laser welding;

2. Ultrasonic welding: The advantage of this scheme is that the welding is simple, but it takes up more space, and the volume and grouping efficiency of the module will be lower;

3. Laser welding: At present, this scheme is the most widely used, but the structure is slightly different;

4. Laser welding of dissimilar metals: This welding method is also very efficient in grouping and fast in production.

 

Good quality lithium battery top cover laser welding machine

 

Because the production process of lithium batteries is complex and the safety requirements are high, one of the key process technologies in the production process is laser welding technology; the laser welding process of power battery includes battery soft connection welding, top cover welding, sealing nail welding, module and PACK welding.

Because of its fast speed and high precision, the laser welding machine has low welding material loss, small
deformation of the welded workpiece and high welding quality during the welding process, which can greatly improve the safety and reliability of the power battery.

 

Specific applications of laser welding technology in lithium battery manufacturing:

 

1. Spot welding of battery poles

The materials used for the battery electrode strips include pure aluminum strips, nickel strips, aluminum-nickel composite strips, and a small amount of copper strips. The welding of battery electrode strips generally uses pulse welding machine. Because of its good beam quality and small welding spot, it is suitable for high reflectivity aluminum strip, copper strip and narrow-band battery electrode strip (the width of the electrode strip is less than 1.5mm). ) The welding has unique advantages.

 

2. Welding of battery tabs

The tabs are usually divided into three materials. The positive electrode of the battery uses aluminum (Al) material, and the negative electrode uses nickel (Ni) material or copper-plated nickel (Ni-Cu) material. In the manufacturing process of power batteries, one of the steps is to weld the battery tabs and poles together.

In the production of the secondary battery, it needs to be welded with another aluminum safety valve. Welding must not only ensure the reliable connection between the tab and the pole, but also requires a smooth and beautiful welding seam.

 

3. Welding of battery explosion-proof valve

The welding of the battery explosion-proof valve adopts pulse laser welding, and continuous sealing welding is realized through the overlap and covering of the welding spot and the welding spot, but the welding efficiency is low, and the sealing performance is relatively poor. Continuous laser welding can achieve high-speed and high-quality welding, welding stability, welding efficiency and yield can be guaranteed.

 

4. The battery shell and the cover plate are sealed and welded

The battery shell materials are aluminum alloy and stainless steel, of which aluminum alloy is the most used, generally 3003 aluminum alloy, and a few use pure aluminum.

Stainless steel is the material with the best laser weldability, especially 304 stainless steel. Whether it is pulsed or continuous laser, welds with good appearance and performance can be obtained;

The laser welding performance of aluminum and aluminum alloys varies slightly depending on the welding method used. Except for pure aluminum and 3 series aluminum alloys, there is no problem with pulse welding and continuous welding. For other series of aluminum alloys, continuous laser welding is the best choice to reduce crack sensitivity.

 

5. Welding of power battery module and pack

The series and parallel connections between power batteries are generally completed by welding the connecting piece and the single battery. The materials of the positive and negative electrodes are different. Generally, there are two kinds of materials: copper and aluminum. Because copper and aluminum are welded by laser, they can form brittle compounds. To meet the application requirements, ultrasonic welding is usually used, and laser welding is generally used for copper and copper, aluminum and aluminum. At the same time, since copper and aluminum conduct heat very quickly, have a very high reflectivity to the laser, and the thickness of the connecting piece is relatively large, it is necessary to use a higher-power laser to achieve welding.