Xiao Qi
In the field of power battery manufacturing, the sealing nail is an important part of the battery pack, is the last process of the square aluminum shell lithium-ion battery in the assembly, after the battery cell is encapsulated into the battery shell, a liquid injection hole is generally left on the shell for the injection of electrolyte, after the electrolyte is injected, the rubber plug is plugged, and the final shell is sealed at the sealing nail welding station, so as to ensure the sealing safety and reliability of the battery.
As the last process, while taking into account efficiency, its pass rate is also crucial, and the first pass rate of sealing nails usually needs to meet 99.5% or even higher, in which the stability of the laser used for cleaning and welding of the injection hole plays a key role.
Have you cleaned your filling holes?
In the process of liquid injection and handling, the electrolyte will remain in the cover plate holding tank, so before the sealing nail is welded, the injection hole must be cleaned first, and the existing cleaning schemes, including dry ice cleaning, CO2 laser cleaning, ordinary fiber laser cleaning, etc., can not completely remove all electrolyte residues, because,
- Dry ice cleaning can only deal with liquid electrolytes with small oil film accumulation thickness;
- CO2 laser cleaning has extremely low efficiency in removing contaminants from thicker hardened (solid) bulk electrolytes;
- It is difficult for ordinary fiber pulsed lasers to solve the problem of oil infiltration after cleaning for liquid electrolytes, and it is difficult to cover a drop of about 1mm because of its short depth of focus.
Figure 1, Schematic diagram of the type of contamination in the injection hole
Fig. 2, schematic diagram of the structure of the contaminated area of the injection hole
01
How do we respond to the challenges?
Obviously, these challenges, for IPG, are not a problem.
IPG YLPN lasers are highly effective at dealing with these contaminants, regardless of their type and location, and not only that, but there is virtually no damage to the surface of the cleaned base metal.
- CT=1.5s @ Ф15mm；
- The drop difference is 1mm, and the cleaning effect of the upper and lower surfaces is consistent;
- The cleaning effect of the concave inclined plane & wall corner position is better, which is consistent with the plane position.
02
Sealing nail welding, have you chosen the right laser?
Let's intuitively understand the difference between IPG fiber lasers and traditional lasers through a set of comparisons.
IPG
Fiber lasers VS conventional lasers
03
Answer, QCW quasi-continuous wave lasers
As IPG's solution for seal nail welding, let's first take a look at the QCW quasi-continuous wave laser and see what it has to offer.
QCW quasi-CW lasers can compress the output CW laser into extremely narrow pulses and emit them, thereby increasing the peak power of the light source by 10X orders of magnitude to obtain high peak volume short pulses.
IPG YLM-600/6000-QCW-AM
Quasi-continuous-wave fiber lasers
With all that said, let's see how QCW quasi-CW lasers compare with traditional YAG pulsed lasers.
From the figure, we can clearly see that QCW quasi-CW lasers provide 2 times the welding speed of YAG pulsed lasers with a footprint of 3.8%, 10 times the wall-plug conversion efficiency, and they can provide more than 99.85% yield.
IPG QCW seal nail weld surface and metallographic diagram
summary
It can be seen that the correct selection of the right laser for injection hole cleaning and seal nail welding can greatly improve efficiency and yield, reduce maintenance and save costs.
IPG QCW quasi-continuous wave fiber lasers can not only be used for seal nail welding, but also have a wide range of application prospects in power battery manufacturing, automobile manufacturing, electronic equipment manufacturing and other fields, and whether you want to perform process verification, or just want to get inspired by experienced laser engineers, please scan the QR code below to contact us, we are always there for you!