The advantage of laser welding lies in the wide variety of materials that can be welded and the ability to weld between different materials.

During the welding process of power lithium-ion battery, the welding process technicians will select the appropriate laser and welding process parameters according to the battery material, shape, thickness, tension requirements, etc., including welding speed, waveform, peak value, welding head inclination angle, etc. to set reasonable The welding process parameters to ensure that the final welding effect meets the requirements of power lithium-ion battery manufacturers.

How many welding methods are there for lithium batteries?

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

2. Ultrasonic welding: The advantage of this solution is that the welding is simple, but it takes up a lot of space, and the volume 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 has high group efficiency and fast production speed.

Difficulties in laser welding of lithium batteries:

1. There are two main types of pores in the laser welding process of aluminum alloys: hydrogen pores and pores generated by bubble bursting. Because the cooling rate of laser welding is too fast, the hydrogen hole problem is more serious, and there is another type of hole caused by the collapse of the small hole in the laser welding.

2. Since aluminum alloys are typical eutectic alloys, hot cracks are prone to occur during welding, including weld crystallization cracks and HAZ liquefaction cracks. Due to the segregation of components in the weld area, eutectic segregation occurs and grain boundary melting occurs. Under the action of stress Liquefaction cracks will form at the grain boundaries and reduce the performance of the welded joint.

Other difficulties:

1. Welding of soft-package tabs requires higher welding tooling. The tabs must be pressed firmly to ensure the welding gap.

2. The welding of the cylindrical cell is mainly used for the welding of the positive electrode. Due to the thin shell of the negative electrode, it is very easy to be welded through.

3. When the square battery combination is welded, the poles or connecting pieces are polluted and thick. When the connecting pieces are welded, the pollutants are decomposed, and it is easy to form welding explosion points and cause holes; the battery with thin poles and plastic or ceramic structural parts under it, Easy to weld through. When the pole is small, it is easy to be welded to the point of burning of the plastic, forming an explosion point.

Compared with traditional welding, laser welding has the following advantages:

First of all, laser welding has high energy density, small welding deformation, and small heat-affected zone, which can effectively improve the accuracy of parts. The weld is smooth without impurities, averagely dense, and does not require additional grinding work; secondly, laser welding can be precisely controlled, focusing light Small point, high-precision positioning, easy to achieve automation with robotic arms, improve welding efficiency, reduce man-hours, and reduce costs; in addition, when laser welding thin plates or thin-diameter wires, it is not as easy to be troubled by melting back as arc welding.