New energy vehicle power battery carbon dioxide co2 laser marking machine Application

Since its introduction in 1990, lithium batteries have been favored by 3C digital, power tools and other industries due to their high energy density, high voltage, environmental protection, long life and fast charging. contribution is particularly outstanding. As a lithium battery industry that provides power sources for new energy vehicles, it has huge market potential and is an important part of the national strategic development. It is expected that the industry scale is expected to exceed 160 billion yuan in the next 5-10 years.

Welding of new energy vehicles

As the core component of new energy vehicles, the quality of power battery directly determines the performance of the whole vehicle. Lithium battery manufacturing equipment is generally divided into three types: front-end equipment, mid-end equipment, and back-end equipment. The equipment precision and automation level will directly affect the production efficiency and consistency of products. As an alternative to traditional welding technology, laser processing technology has been widely used in lithium battery manufacturing equipment.

This paper expounds the process characteristics of laser welding in the field of lithium batteries through the application of lasers in the power battery industry, and lists the process characteristics and equipment development trends of multiple processes . From the manufacture of lithium battery cells to the grouping of lithium battery PACK line automated production lines, welding is a very important manufacturing process. The conductivity, strength, air tightness, metal fatigue and corrosion resistance of lithium batteries are typical of batteries. Welding quality evaluation standard. The selection of welding method and welding process will directly affect the cost, quality, safety and consistency of the battery. Next, the author will take you to understand the various applications of laser welding in the field of lithium batteries.

1. Welding of battery 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 will rupture to prevent the battery from bursting. The safety valve has an ingenious structure, and this process has extremely strict requirements on the laser welding machine process. Before continuous laser welding was used, the welding of battery explosion-proof valves was carried out by pulsed laser welding, and continuous sealing welding was realized by overlapping and covering the welding spot and the welding spot, but the welding efficiency was low and the sealing performance was relatively poor. Continuous laser welding can achieve high-speed and high-quality welding, and welding stability, welding efficiency and yield can be guaranteed.

2. Welding of battery tabs

The tabs are usually divided into three materials, and the positive electrode of the battery is made of aluminum (Al ) material, and the negative electrode uses nickel (Ni) material or nickel-plated copper (Ni-Cu) material. In the manufacturing process of power batteries, one of the links is to weld the battery tabs and poles together. In the manufacture of the secondary battery, it needs to be welded with another aluminum safety valve. Welding not only needs to ensure the reliable connection between the tab and the pole, but also requires the welding seam to be smooth and beautiful.

3. Spot welding of battery poles

The materials used for battery poles include pure aluminum strips, nickel strips, aluminum strips Nickel composite tape and a small amount of copper tape, etc. The welding of battery strips generally uses a pulse welding machine. With the emergence of IPG's QCW quasi-continuous laser, it has also been widely used in the welding of battery strips. At the same time, due to its good beam quality, the welding spot can be small. , which has unique advantages in the welding of aluminum strips, copper strips and narrow-band battery strips with high reflectivity (the strip width is less than 1.5mm).

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

The shell materials of the power battery are aluminum alloy and stainless steel Among them, most of them use aluminum alloys, generally 3003 aluminum alloys, and a few use pure aluminum. Stainless steel is the best material for laser weldability, and both pulsed and continuous lasers can obtain welds with good appearance and performance. Using continuous lasers to weld thin-shell lithium batteries, the efficiency can be increased by 5 to 10 times, and the appearance and sealing performance are better. Therefore, there is a trend to gradually replace pulsed lasers in this application field.

Welding of new energy vehicles

5, power battery module and PACK welding

The series and parallel connection between power batteries is generally through The welding of the connecting piece and the single battery is completed. The positive and negative materials are different. Generally, there are two kinds of materials: copper and aluminum. Because the brittle compound is formed after laser welding between copper and aluminum, it cannot meet the requirements of use. Ultrasonic welding is usually used. , Copper and copper, aluminum and aluminum are generally laser welded. At the same time, due to the fast heat transfer of copper and aluminum, and the high reflectivity to the laser, the thickness of the connecting piece is relatively large, so it is necessary to use a higher power laser to achieve welding.