Although many people still have certain concerns about the range and safety of electric vehicles, the development of new energy vehicles is an inevitable choice for China to become an automotive powerhouse and a strategic move to solve the climate problem and advocate the concept of green development. With the firm promotion at the policy level, some of the current problems of electric vehicles will eventually be overcome, and it is only a matter of time before new energy vehicles replace fuel vehicles.
New energy vehicles are already an unstoppable new force in the market. 2023 data from the Ministry of Industry and Information Technology in early 2023 showed that China's new energy vehicles continued to grow explosively in 2022, remaining the first in the world for eight consecutive years, and the market penetration rate hit a new record high.
Data from the China Association of Automobile Manufacturers shows that as of May 2023, China's new energy vehicle production and sales were 713,000 and 717,000 units, up 11.4% and 12.6% YoY, and up 53% and 60.2% YoY, respectively, with a market share of 30.1%.
Cumulatively, from January to May 2023, the cumulative production and sales of new energy vehicles in China completed 3.005 million and 2.94 million units respectively, with a cumulative growth of 45.1% and 46.8% respectively, and a market share of 27.7%.
Recently, the 20 millionth new energy vehicle produced in China has rolled off the line in Guangzhou! China is expected to become the first country in the world to cross the era of annual sales of new energy vehicles reaching 10 million units.
The continuous growth of production and sales has made the domestic electric vehicle manufacturing market hotter than ever. The laser technology is indispensable in many aspects from lithium battery manufacturing to vehicle body and parts manufacturing. The continuous and rapid growth of the incremental market brings huge business opportunities that speak for themselves. With the attractive business opportunities, it is not surprising that manufacturers are flocking to the new energy vehicle market.
The application of laser in power battery manufacturing
Power battery is the power source of electric vehicles, currently dominated by lithium batteries. China's power battery industry continues to lead the world, 70% of power batteries are made in China.
The production process of lithium batteries can be mainly divided into three parts: pole manufacturing, cell manufacturing, and battery pack assembly. In the manufacturing process of lithium batteries and battery packs, a large number of laser cutting, welding, and removal/cleaning processes are required.
(1) Laser cutting
Laser cutting technology can be applied to the pre-processes such as lug cutting and forming, pole slitting and diaphragm slitting in the manufacturing process of lithium batteries.
For example, lug cutting requires smooth and burr-free, no rolled edges, and no risk of damaging the battery separator; in addition, as the specific energy of lithium batteries becomes higher and higher, the resistance inside the battery becomes smaller and smaller, and the lithium battery lugs are developing from single lug to multi-lug and from multi-lug to full lug. The demanding process requirements make ultrafast lasers stand out. They can cut multiple materials and different thicknesses of the pole lugs, and the cold processing achieves high quality cutting results.
For these metal foil cuts, infrared pulsed lasers can be used, or green and ultraviolet products can be used if higher quality cuts are required. From the perspective of pulse width, the current industry applications are mainly nanosecond and picosecond lasers, of which picosecond products gradually occupy the mainstream; while femtosecond lasers are also used, but in terms of stability to adapt to the continuous operation of industrial production lines, further efforts are needed.
The diaphragm in lithium batteries, mainly polyethylene (PE), polypropylene (PP) with excellent mechanical properties, chemical stability and relatively inexpensive polyolefin diaphragm. Cutting this type of material, UV laser is most suitable.
With increasingly shorter wavelengths and shorter pulse widths of green light, ultraviolet light source in power, stability and other aspects of the performance continues to improve, the laser will achieve more efficient and higher quality cutting of these film products in lithium batteries.
(2) Laser welding
Welding is the most important process used in the production of lithium batteries and battery packs.
In the manufacturing process of cells, modules and packs of Li-ion batteries, there are more than 20 processes that require welding to achieve conductive connections or sealing functions. The vast majority of them require laser welding to achieve.
In square-case batteries, laser welding is required for the shell, sealing nails, cover assembly and sealing; in cylindrical batteries and modules, laser welding is required for the pole lugs, caps and busbars.
This type of welding, the material for the thinner aluminum and copper-based, for this kind of high anti-material welding, the use of infrared light welding prone to spatter and many other defects, compared to the green and blue light absorption efficiency is higher, welding quality is also better.
Copper's high absorption rate in the blue light band makes it more preferable to use blue light lasers for welding. The blue laser with increasing power and beam quality will be a powerful tool for lithium battery welding applications.
Recently many manufacturers at home and abroad have been deepening the field of blue light laser, and there are already a variety of power available such as 100W, 800W, 1kW and 4kW.
The welding process is relatively complex, in order to better monitor the quality of welding, there are also many manufacturers have developed a real-time monitoring program for laser welding, according to the feedback information obtained on the quality of the weld seam, welding parameters can be adjusted to the best state in a timely manner.
(3) Laser removal/cleaning
Laser pole cleaning
In the manufacturing process of lithium batteries, the coating in the area of the pole lug to be welded needs to be cleaned before the pole lug is welded. The coatings to be removed are graphite and lithium metal oxide to expose the copper or aluminum foil tabs.
The key to this step is to remove only the coating material without damaging the metal foil beneath it. Compared to mechanical scraping and other removal methods, the laser cleaning and removal solution causes minimal damage to the copper foil and has the advantage of being effective, efficient and green, making it the industry's preferred ideal solution for removing the coating. For this step of the process, pulsed infrared lasers are mostly used.
In addition, semiconductor lasers are also being used directly in the electrode drying process for lithium batteries.
Laser applications in vehicle and component manufacturing
The use of laser technology in vehicle and component manufacturing can be said to be almost ubiquitous and has been used for decades, and is relatively not a new application. However, the large demand in the market and the relentless pursuit of higher manufacturing quality continue to keep this market exploring forward.
There are many places where laser welding is used in the manufacture of complete vehicles and components, including: transmission gears, oil filters, hydraulic tappets, airbag ignitors, fuel injectors, ABS battery valves, seats, lights, sensors and other components; and body parts such as roofs, doors, engine tops and tailgates, all of which are active in laser welding.
Laser welding of the body, the strength can be increased by more than 30%, the car's safety is higher; the use of laser welding of automotive parts, can reduce the volume to meet the miniaturization of components, the development trend of lightweight vehicles.
Take the current more mainstream flat wire drive motor as an example, the laser process involved includes motor silicon steel welding, hairpin (hairpin) flat wire de-painting and welding, as well as the motor bus welding.
Blue light is the preferred tool for welding copper, and high power blue lasers of 1kW and 4kW are already available; other manufacturers have proposed the use of blue lasers with infrared lasers to weld copper of different thicknesses to achieve better welding quality and improve efficiency.
In addition to welding applications, laser technology can also be used for the cutting of high-strength steel for bodywork, cutting of airbag materials, cutting of automotive interior materials, traceability marking of engines, tires and other parts, flat copper wire de-painting and many other aspects. It is understood that in Europe and the United States and other developed industrial countries, 60% to 80% of automotive parts are completed with laser processing. With the continued development of China's new energy vehicle market, laser technology will usher in a huge potential application market; along with the advancement of applications, I believe that laser technology itself and application effects, will also continue to evolve forward.
