43% Faster! Beam Turnable Laser Overcomes The Welding Problem Of Lithium Battery

Lithium-ion batteries have the advantages of high specific energy, long cycle life, low self-discharge, no memory effect and no pollution, and are widely used in various electronic devices and vehicles.

From the manufacture of lithium battery cells to the formation of battery packs, multiple welding processes are an important part of the battery manufacturing process, which will directly affect the cost, quality, safety and consistency of the battery.

However, conventional fiber lasers are often used in the welding process of lithium battery production, and there are problems of unstable welding process, spatter, pores, rough appearance of the weld, poor consistency and high-grade aluminum weld cracks.

Raycus RFL-ABP series beams tunable fiber laser shows sufficient advantages in welding quality and welding efficiency, and can perfectly solve the above problems.

The beam tunable fiber laser(https://www.mornlasercnc.com/products/laser-welding-machine/) is a two-in-one beam composed of a central beam with a small spot and high energy density and a larger ring beam. Compared with other lasers (gas, solid, semiconductor, conventional fiber lasers), beam tunable fiber lasers has the following welding advantages:

● The power of the center/circular spot can be adjusted independently to achieve high-quality, high-speed and uniform welding;
● Less welding spatter, almost no spatter;
● Reduce the welding seam porosity and crack tendency;
● The keyhole is larger and more stable, the welding seam is formed stable, and the consistency is good;
● Suitable for high-speed welding of lithium battery, automobile manufacturing and general industry.

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Beam turnable fiber laser

Examples of welding applications in the lithium battery industry

Regarding the laser welding process of beam tunable fiber lasers in the lithium battery industry, we use Raycus RFL-ABP series beam tunable fiber lasers to conduct related process experiments, let’s see how the welding effect is!

Battery shell welding

The thickness of the battery shell material is usually 0.2~2mm. Such parts have strict requirements on welding spatter and the appearance of the weld seam. They mainly require airtightness and do not have high requirements on the weld seam strength.

When conventional fiber laser welding is used, there will be air holes and blast holes that can cause sealing problems. In addition, many spatters and unstable welding process are also welding problems.

The use of Raycus beam adjustable fiber laser for battery shell sealing welding can significantly increase the welding speed, the two-in-one beam keyhole is more stable, the welding process is more stable, and the weld formation is more beautiful.

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Sealing welding of square cell shell

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Cylindrical battery shell sealing welding

The welding speed of the square battery shell is as high as 350mm/s (200 mm/s is the industry standard for battery welding speed, and the Raycus RFL-ABP series beam adjustable fiber laser is used for welding, and the speed is increased by 43%);

● The welding time of the cylindrical battery shell is about 0.9s/piece;
● There is almost no spatter in the welding process;
● The welding seam is formed uniformly, and there are no defects such as false welding, blast holes, cracks, and pores;
● There is no light leakage or slag leakage inside the battery cell;
● The tightness meets the requirements, which greatly improves the product qualification rate.

Adapter piece welding

Adapter sheet welding is an extremely important process in the production process of battery cells. It serves to connect the cover plate and the cells. The quality of the welding seam directly affects the performance of the entire cell.

In order to ensure the overcurrent capability, the joint width of the weld joint is required to be larger. Secondly, there should be no residual spatter during welding to avoid short circuit inside the battery and affect battery safety performance.

Using Raycus beam adjustable fiber laser with galvanometer welding head, reasonable adjustment of process parameters such as center power, ring power, spiral line spacing, etc., can realize circular ring welds or spiral solid circular welds, effectively increasing the connection width of the joint surface , Improve the quality of welded joints.

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Circular weld (above: aluminum alloy, bottom: red copper)

The welding speed of the adapter piece is higher than 110mm/s;

● The strength of the welded joint is higher than 2kN;
● The welding seam is formed uniformly and there is almost no spatter.

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Spiral solid round weld (left picture: aluminum alloy, right picture: red copper)

● The width of the weld connection is higher than 6mm, and the connection area at the joint surface is very large;
● The weld seam is beautifully formed and has no defects such as cracks.

Busbar welding

The bus bar is a bridge that connects a single cell. In order to ensure sufficient over-current capability, the connection must have sufficient width and low porosity. The weld penetration depth of the bus bar is generally between 2~4mm, which requires the strength of the weld. It is relatively high, and the requirements for weld surface quality and spatter are also stricter. 

Using Raycus beam adjustable fiber laser with galvanometer welding head for swing welding, by optimizing the power ratio of the center spot and the ring spot, and reasonably adjusting the swing parameters of the galvanometer, it can effectively increase the connection width of the joint surface and greatly reduce it. The pores inside the weld are optimized for weld formation.

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Busbar welding

● Weld connection width> 2mm;
● The mechanical properties of the welded joint are excellent, and the fractured part of the tensile test is the base material of the upper plate;
● The weld seam is well formed, with very little spatter.

Battery module side plate welding

Module side panels generally use 5 series aluminum alloy and 6 series aluminum alloy for combined welding to ensure the strength of the outer frame. Welding cracks are a major problem in the welding of 5 series and 6 series aluminum alloys. How to ensure that the connection width is more than 2mm and obtain a “U-shape” “Welds without undercuts and other defects make it even more difficult to improve the quality of welded joints.

Using Raycus beam adjustable fiber laser with galvanometer welding head for swing welding, through complex process parameter adjustment, it can reduce welding seam porosity and cracking tendency, and improve the quality of welded joints.

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Module side plate: stack welding joint

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Module side panel: butt joint connector

The welding speed exceeds 80mm/s;

● The connection width of the overlapping surface of the overlap welding joint> 2mm;
● The shape of the weld is close to the “U” shape;
● The mechanical properties of the welded joint are excellent, and the fractured part of the tensile test is the base material of the upper plate;
● The welding seam has no defects such as cracks and undercuts, and the shape is uniform.

Through rigorous testing and customer field application performance, Raycus’ RFL-ABP series beam tunable laser performs very well in lithium battery welding applications, with a speed increase of about 43%, higher weld quality and more beautiful appearance, and it is bound to bcome Powerful models in the field of battery manufacturing and high-end welding.

 

 


Post time: Apr-13-2021
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