Introduction to laser welding of various parts of the battery cover
The main application markets of laser welding and automation equipment are the new energy power battery industry and the energy storage battery industry. Next, let's introduce the practical application and solutions of the battery industry.
At present, the conventional battery structure is generally divided into circular batteries, square batteries, and pouch batteries.
Let's first talk about the cover plate of the square power battery and the welding application of the cover plate.
As a mainstream prismatic battery, there are many processes on the cover that require laser welding. Let's first look at the important components on the cover.
1. Sealing nail: To prevent the electrolyte from reabsorbing moisture in the air, place the sealing nail in the holding tank so that there is an uneven annular gap between the sealing nail and the holding tank; use the second laser to spot weld the seal The nail is positioned and fixed in the holding groove, and at the same time, the second protective gas is blown to the action of the second laser; the sealing nail and the cover plate are welded along the annular gap by the second laser.
2. Explosion-proof valve: The explosion-proof valve of the battery is a thin-walled valve body on the battery sealing plate. When the internal pressure of the battery exceeds the specified value, the explosion-proof valve body ruptures to prevent the battery from bursting. The safety valve (function: to control the pressure not to exceed the specified value) has an ingenious structure. This process is very important for laser.
The welding process requirements are extremely strict. Before continuous laser welding was adopted, the welding of battery explosion-proof valves was welded by pulsed laser welding, and continuous sealing welding was realized by overlapping and covering between welding spots and welding spots, but the welding efficiency was low and the sealing performance was low. relatively poor. Continuous laser welding can achieve high-speed and high-quality welding, and welding stability, welding efficiency and yield can be guaranteed.
3. Pole: The tabs are usually divided into three materials. The positive electrode of the battery is made of aluminum (Al), and the negative electrode is made of nickel (Ni) or nickel-plated copper (Ni-Cu). In the manufacturing process of power batteries, one of the links is to weld the battery tabs and poles together. In the production of the secondary battery, it needs to be welded together with another aluminum safety valve. Welding not only needs to ensure the reliable connection between the lug and the pole, but also requires smooth and beautiful weld seam.
4. Flexible connection: The top cover of the power battery with creases is connected with positive and negative electrodes, including a rectangular positive electrode flexible connection piece and a negative electrode flexible connection piece. The connecting piece is made of multi-layer T2 pure copper foil superimposed welding. Both the positive flexible connecting piece and the negative flexible connecting piece are provided with the first crease groove and the second crease groove that run through the entire flexible connecting piece. The first crease The groove is arranged in the middle of the positive flexible connecting piece and the negative flexible connecting piece, the second crease groove is arranged on one side of the first crease groove, and the other side is provided with a welding joint distribution area, and a welding joint distribution area is provided on the welding joint distribution area has multiple welded joints.
The laser battery explosion-proof valve automation workbench is suitable for the welding of new energy power battery explosion-proof valves. The scheme adopts the working mode of rotating double stations, manually loading the battery cover to the fixture tray, switching between loading and unloading and welding, and realizing the explosion-proof valve welding.
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