At present, the pace of realizing new energy in the automobile industry is accelerating, and the demand for new energy vehicles is also increasing. In order to speed up the production of new energy vehicles to obtain the maximum benefit of enterprises, the key is to improve the modular production efficiency of the battery pack of new energy vehicles.

Replacing the traditional welding technology with laser welding technology for the production of new energy vehicle power battery modules can not only greatly improve the production speed, but also improve the yield of lithium battery pack modules and the safety of the welding process.

1、 Basic principle of laser welding power lithium battery

The basic principle of laser welding of lithium battery is: the laser beam transmitter with high power and high density emits light to the welding node of lithium battery after converging through the lens. After the high-strength laser is absorbed by the metal surface of the node, the heat energy is generated after the interaction between the media material and the battery welding node. The metal on the surface is melted by the laser and then rapidly cooled. After cooling, the welding is completed after the solder and the weldment crystallize.

2、 Development status and technical advantages of laser welded lithium batteries

2.1 Development status of laser welded lithium battery

Among many laser welding equipment in China, only more than ten laser enterprises, such as Huagong Laser, Pentium and Han's Laser, have relatively mature welding technology and master the core welding process. For laser welding of Li+battery shell, the qualification rate of laser technology and welding quality of these enterprises can also meet the needs of industrial production.

The research and development of the laser welding equipment and system control module for Li ü+power battery focuses on improving the efficiency and quality of laser welding by changing the clamping mode of the laser welding gun and adjusting the laser welding posture. Compared with the foreign laser welding technology, there is still much room for improvement.

2.2 Technical disadvantages of traditional welding lithium battery

Traditional power lithium battery welding is mainly manual electric welding and gas welding, and the welding process requires continuous filling of shielding gas at the welding junction to ensure the welding quality. This process is manually pressed and clamped by workers, which is often difficult to control its size, and the assembly quality is uneven. In the later matching process of lithium battery pack packaging and distribution system, unnecessary trouble will also be brought.

At the same time, manual welding not only affects production efficiency, but also inevitably has potential safety hazards in the welding process; At the same time, it is difficult to control the manual pressure value within the accurate range, which may lead to loose internal connection of the battery case after welding, which is bound to pose a threat to driving safety in practical applications.

2.3 Technical advantages of laser welding lithium battery

Compared with traditional welding technology, laser, with its unique advantages of high energy density and cylinder transmission after converging beam, can make the metallographic change range of the metal in the heat affected zone of welding smaller. Secondly, laser welding belongs to non-contact welding, which will not produce electrode pollution, machine tool loss and other problems during welding, and can also adapt to different types of lithium battery shell solder; At the same time, the crater deformation is smaller, the welding speed is fast, the precision is high, and it is easier to realize automation.

As a leader in automatic integrated laser welding, Huagong Laser actively integrates emerging laser welding processes and promotes the key transformation of laser welding from a purely manual or semi-automatic production line to a fully automated production line. The laser welding solutions launched by Huagong Laser are also relatively favored and recognized by the industry, taking its new energy battery module and battery box (tray) welding automation production line as an example.

When it is applied to laser welding battery shield housing or thin diameter wiring channel, it will not be subject to the limitation of delayed melting as arc welding. As a result, the weld is smooth, the welding track is beautiful and neat, the weld is not easy to penetrate, and the metal internal defects are smaller, which also saves the subsequent reprocessing process (Figure 2 and Figure 3) and reduces the additional production costs.

3、 Application scenario of laser welding in new energy industry

In addition to the above laser welding applied to the power lithium battery of new energy vehicles, laser welding is also more widely used in the new energy field. For example, the laser welding of the outer protective shell of the sealed new energy power battery uses the laser conduction welding mechanism to ensure the sealing and achieve fusion welding and splicing of different materials.

For lithium battery welding operation requiring special protection measures, laser welding can still maintain good protection function by matching with specific gas mixing welding.

4、 Development prospect of new energy power lithium battery for laser welding

In a word, laser welding technology makes perfect use of various advantages of laser beam to carry out welding tasks. In the future, laser welding technology will be more flexible to adapt to the welding tasks of lithium battery modules with different new energy power battery materials and different shapes. It will be an emerging welding technology urgently needed by the manufacturing industry in the future.

At the same time, the new energy power battery module, as the key core of new energy vehicles, is not only related to the driving performance of the whole vehicle, but also related to the safety experience of users. It is the development goal of Huagong Laser and other major laser enterprises to promote the comprehensive popularization of automatic laser welding production line in the new energy lithium battery industry.