The laser is at the center of many solutions when it comes to the global e-mobility trend. Here are a few examples of laser cutting applications in battery cell manufacturing and assembly. Article by Trumpf.
The worldwide mobility transition is in full swing. The demand for components for electric cars and alternative drives is rising continually. In particular, high-performance components directly involved in the production of batteries, electric motors and power electronics for electromobility are at the center. More and more companies, predominately automotive suppliers, are also demanding new manufacturing solutions and technologies for alternative drive concepts, including the fuel cell.
The laser is at the center of many solutions. It connects battery cells into modules or packs. It ensures tightness and crash safety when joining battery packs and trays. It scores highly thanks to its green wavelength when copper welding contact parts without spatter. And it provides high-tensile connections in e-drives, which withstand the highly dynamic requirements.
Manufacturing Battery Cells
Battery cell manufacturing is subdivided into electrode manufacturing and cell assembly. Electrode manufacturing requires a high variety of different process steps: mixing of the slurry, coating, drying, calendaring as well as shaping, folding and stacking of the coated electrode foil. Some of them required laser technology:
- Micro structuring of the electrode surface with ultra-short pulse lasers, for example, reduces subsequently the charging time of battery cells.
- Drying of electrodes with VCSEL laser technology to complement conventional drying ovens by reducing the footprint and increase efficiency.
- Cutting and shaping of coated electrode foils with ns lasers into the required format, increasing quality and productivity. Common foil materials are aluminium (cathode) with a 5-14 µm thickness as well as copper (anode) with a thickness of 9-13 µm. Very often, these foils are coated. Cutting these foils with TruFiber laser sources enables burrs of less than 5 µm and HAZ of less than 40µm.
In the cell assembly, the steps are contacting, packaging, formation, and aging. Laser technology is used here mainly in welding applications for the internal contacting of battery cell components and the closing of prismatic cell formats:
- Green laser wavelength for the very defined and repeatable welding of copper materials.
- High power IR lasers combined with Trumpf’s BrightLineWeld technology for spatter free welding of aluminium or copper materials.
Both laser applications enable the highest mechanical strength and lowest electrical resistance in welding of ≤100 foils together to a stack.
On the cell level, besides these different welding applications, there are also some upcoming laser applications for surface processing like cleaning, de-coating or micro structuring with short or ultra-short pulse lasers.
Process stability is a key factor in the battery cell production. Therefore, all these laser technologies have a direct impact on the efficiency and performance of the battery.
Battery Module Assembly
After the battery cell manufacturing process, the single cells will be assembled to a battery module. The electronics and battery pack assembly have an enormous variance of different module designs. But all are based on prismatic, pouch or cylindrical cell formats.
Laser technology is used in welding of busbars, meaning the electrical contacting of single cells to a battery module, or other current carrying components. Due to the enormous number of different designs, material combinations and thicknesses, the full TRUMPF laser portfolio in terms of power, wavelength, beam quality is applied.
- Especially for thicker aluminium busbars with welding depths mostly >2 mm and welding speeds of minimum 100 mm per second, the TruDisk laser series with patented beam shaping technology BrightLineWeld is the best choice since every single weld must be exactly the same and spatter projections must be avoided.
- For the welding of dissimilar material combination like Al/Cu or Al/steal, we mostly recommend single mode IR lasers with a very high beam quality e.g. you can use the TruFiber Series for such applications. These lasers create a very small intermetallic phase in the welding seam, which is important for a strong joint of materials with quite different melting temperatures. By using different welding patterns, you can join Al with Cu or even the other way around. Typically, by oscillating the laser beam with a scanner optic to increase the cross-section area. For the contacting of cylindrical cells, the sheet thicknesses are usually in the range 0.2 – 0.5mm, and many times dissimilar material combinations or with coatings.
For most of the installations in battery and module manufacturing, TRUMPF lasers, optics and sensors are integrated in automated high-volume production lines, while its TruLaser Station and TruLaser Cell series are suitable in small- and medium-production volumes.
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