In recent years, driven by electronic technology and 5G mobile communication technology, the trend of global electronic products becoming thinner and more precise is  more and more obvious: the new energy industry is also moving forward.

The most concerned electronic products, smart phones and notebook lithium batteries are all new rechargeable batteries. Under the consumer's demand for high endurance, high security and personalization of electronic products, major battery manufacturers are also competing to produce new rechargeable lithium batteries with higher energy density, diverse specifications and materials.
 

Lithium battery is also widely used as the main power supply in various electronic products due to its strong endurance and high safety performance.

With the in-depth development of 3C electronics industry, higher requirements are put forward for the assembly and welding accuracy and quality of supporting batteries. It is difficult for traditional welding technology to meet the high standard welding requirements of lithium battery lug. In contrast, laser welding technology can meet the diversity of processing technology of lithium battery lug, such as welding of dissimilar materials (stainless steel, aluminum alloy, copper, nickel, etc.). Irregular welding track and excellent welding appearance. Solid welds, more detailed welding points and more accurate positioning welding areas. Laser welding not only improves the uniformity of product welding, but also weld the ring firmly, becoming the best welding process for lithium battery.

Welding of pole lug of lithium battery cell with FPC and busbar

The material of the battery lug is very thin, and the welding difficulty coefficient is relatively high. If the process parameters are not set properly, the fixture is not pressed tightly or the operation is improper, it is easy to cause faulty welding and welding penetration. For this reason, the mirror helix welding method is selected to produce high temperature fusion at the position to be welded instantly, realizing contactless welding, accurate positioning and efficient production of high-quality batteries.

Machine configuration

The laser adopts IPG1500W single-mode continuous laser with core diameter of 14 μ m. The galvanometer is imported from Germany, and the scanning speed can be up to 7000mm/s: collimating 150mm, and the focal length of the field mirror is 170mm.

The tensile test after welding meets the customer's requirements. During the commissioning process, the difficulty encountered is red copper welding. The copper material has good conductivity, but for welding, it is a highly reflective material, and the laser absorption rate is very low, less than 10%. In addition, the material is extremely thin, and it is easy to weld through the material below when the heating area is too large, the time is too long, or the laser power density is not enough, which greatly increases the difficulty of the welding process.

In the early stage, the field mirror with a focal length of 254 mm is used, and the energy density is not enough, so it is easy to have false soldering and weld through; After replacing the field mirror with a focal length of 170mm, the difficulty of debugging is reduced.

The galvanometer laser spiral welding method is adopted, the welding energy is uniform, the shape, penetration depth and firmness of the welding point are good, the appearance is smooth and beautiful, and there is no deformation. The welding effect is as shown in the chart. The spiral welding track is uniform, the line is free of faulty welding, the aluminum foil is free of deformation, and the back of the battery shell is free of welding penetration and other undesirable phenomena. It is firm and reliable, and meets the customer's requirements.

In the application of lithium battery welding, the laser has accumulated the following advantages in a large number of practical applications:

No current passes through the battery to avoid internal breakdown and non-contact welding of the battery, to avoid the deformation of the workpiece due to pressure, and to avoid the instantaneous heating of the precise crystal beam, to avoid the thermal damage of the battery to the welding energy, time uniformity, and the shape and size of the welding point. The welding depth is firm and consistent, the appearance is smooth and beautiful, the heat affected area is small, the equipment is small and portable, and can realize automation, and cooperate with assembly line operation.

In order to cope with the rapid development of electronic products. The demand for notebook pouch batteries is increasing, and laser precision welding machine is the best choice.

About HGTECH: HGTECH is the pioneer and leader of laser industrial application in China, and the authoritative provider of global laser processing solutions. We have comprehensively arranged laser intelligent machine, measurement and automation production lines, and smart factory construction to provide overall solutions for intelligent manufacturing.