"Flow" of 2000mah 18650 battery laser welding technology

　　Laser welding can greatly improve the safety and service life of power batteries.

　　In the manufacturing process of power batteries, there are many laser welding parts, including tabs, flip sheets, seals, bus bars, PACK modules, injection hole packaging, etc., which can realize battery series and parallel connection. It also involves batteries, modules, PACKs, and can also weld diverse materials such as steel, aluminum, copper, and nickel.

　　On square batteries, laser welding is mainly penetration welding and pulse welding. For soft pack batteries, pulse welding is used. The principle is that high-energy-density lasers use heat sources to weld. They have good reliability, low contact resistance, and a high degree of automation, which can greatly improve production efficiency.

　　The advantage of laser welding is to effectively improve the connection reliability, facilitate the lightweight of the module, reduce the internal resistance of the battery, and reduce the loss of heat itself. At the same time, it can work continuously without stopping, has good welding quality and high flexibility. The difficulty and pain point is that the weldment assembly has high precision and requires that the position of the beam on the workpiece cannot be significantly offset. At the same time, the cost of lasers and related systems is relatively high.

　　At the same time, according to Gaogong Lithium Battery, well-known lithium battery companies such as CATL, BYD, Guoxuan Hi-Tech, Yiwei Lithium Energy, Panasonic, and Samsung are involved in the use of laser welding.

　　In terms of laser welding technology, the relatively prominent ones include sealing nail welding, top cover welding, and continuous welding.

　　Sealing nail welding uses pulse welding. The reason is intermittent heat input, small amount of tin and hydrogen, and good effect. The development of sealing nail welding is divided into two stages. The first stage is 7-8mm/s, and the second stage is that the speed has reached 30mm/s, and it will be faster in the future.

　　The first stage of top cover welding is ordinary head welding, which can only achieve 60-80mm/s. Because it is deep penetration welding, sight holes are prone to appear during the welding process, and closures are easy to occur at the end of the sight holes. Electronics How the steam escapes can easily cause frizz on the surface.

　　The second stage is a combination of hybrid welding and high-frequency swing welding, which can solve the problem of rapid closing of the visual hole and greatly improve the welding speed.

　　The third stage is for some companies to start new attempts, such as Haimuxing's high-speed welding of annular spot welding and hybrid welding, which can reach 300mm/s.

　　Continuous welding is characterized by high speed, but it is easy to form heat accumulation. During the cooling process of the instantaneous molten pool, there are no micro-fractures. Among them, continuous laser welding can reach 15mm/s, and physical welding can reach 300mm/s.

　　In general, lithium battery equipment is commonly welded with laser heads and galvanometer laser processing heads, which can achieve high-speed welding of complex trajectories such as S-shaped and spiral shapes, increasing the weld joint area and enhancing the welding strength. You can also connect to the MES system during the welding process to record and adjust various welding parameters in real time to ensure more stable and higher-quality welding.

　　For laser welding equipment, there are three main development trends.

　　First of all, the power of laser welding lasers is getting larger and larger. In this way, in the trend of "cost reduction and efficiency improvement" of lithium battery equipment, precision requirements will become higher and higher, and the position accuracy of welding may also become greater and greater.

　　Wu Hua'an, general manager of Tide Laser, said that laser welding has more controllability in terms of quality and higher welding precision. In the future, it will completely replace bolts, glue and other methods.

　　For example, Raycus Laser’s new 3000W single-module continuous fiber laser has higher photoelectric conversion efficiency (≥35%), better and more stable beam quality, and stronger resistance to high reflection, ensuring thick plate cutting. In order to achieve a more stable and precise cutting effect.

　　Secondly, the data collection capabilities in application scenarios are enhanced, and the ability to control laser welding effects is enhanced. For example, artificial intelligence and big data algorithms are used to conduct three-dimensional model simulation and intelligent prediction of welding effects.

　　Finally, stability, security, and flexibility are enhanced.

　　The representative is Haimuxing Laser, which integrates the 2000W fiber laser imported by Apache into welding equipment. It conducts full welding tests on battery aluminum boxes and reaches a melting width of 0.8mm-1.4mm and a melting depth of 0.6mm-1.1mm. Flange ≤ 60μm, protrusion value ≤ 500μm standard.

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