High-precision laser cutting and welding systems for lithium-ion battery manufacturing

Prior to the advent of laser technology, the battery industry had been using traditional machinery for processing. Compared with traditional mechanical processing, laser processing has many advantages and is gradually being recognized by lithium-ion battery manufacturers. It can be used for metal foil slitting, metal foil cutting, and isolation film cutting. It can also be used for welding of pole lugs, cell shells, sealing nails, flexible connections, explosion-proof, valves, and battery modules.

 

Lithium-ion battery

Lithium batteries are favored by 3C digital and electric tool industries for their high energy density, high voltage, environmental protection, long life, fast charging and other advantages. Their contribution to the new energy vehicle industry is particularly outstanding. In recent years, new energy vehicles have sprung up like rain. Compared with traditional fuel cars, new energy vehicles use lithium batteries as the power source. The lithium-ion battery industry, which is the power source for new energy vehicles, has a huge market potential.

 

Lithium-ion Battery (Li-ion Battery) Lithium-ion battery, also known as lithium-ion battery, is a kind of secondary battery (rechargeable battery), which mainly relies on the movement of lithium ions between the positive and negative electrodes to work. As a new type of clean energy, Li-ion battery can not only provide power for new energy vehicles, but also for various products such as electric trains, electric bicycles, golf carts, etc. This article will introduce you to laser technology in power battery manufacturing and explain why laser cutting systems and laser welding systems are used in lithium-ion battery manufacturing.

 

Laser Cutting Systems

The production of lithium-ion batteries is closely related to a process step. Generally speaking, lithium-ion battery production consists of three parts: pole manufacturing, cell manufacturing and cell assembly. Among these three processes, laser cutting is one of the key processes. The lithium-ion battery processing process requires high precision, controllability and quality of the cutting machine. Die-cutting knives inevitably wear out during use, then drop dust and produce burrs, which may cause dangerous problems such as battery overheating, short circuit and explosion. To avoid the danger, it is more suitable to use laser cutting machine. Compared with traditional mechanical cutting machine, laser cutting system has the advantages of no tool wear, flexible cutting shape, controllable edge quality, higher precision and lower running cost, which is conducive to reducing manufacturing cost, improving production efficiency and greatly shortening the new product die-cutting cycle.

 

Lithium battery, as the core component of new energy vehicles, directly determines the performance of the whole vehicle. With the gradual outbreak of the new energy vehicle market, laser cutting machine will have a huge market potential in the future.

 

Laser Welding System

As the core component of new energy vehicles, the good or bad power battery directly determines the performance of the whole vehicle. Lithium-ion battery manufacturing equipment generally includes three types of front-end equipment, mid-end equipment and back-end equipment. The precision and automation degree of the equipment will directly affect the production efficiency and consistency of the products. As an alternative to traditional welding methods, laser welding machines have been widely used in lithium-ion battery manufacturing equipment. Laser welding machine is an important part of power battery production line. Its principle is an efficient and precise welding method using a high energy density laser beam as the heat source. Compared with traditional welding, laser welding has the advantages of deep melting, fast speed, small deformation, low requirements for welding environment, high power density, not affected by magnetic field, not limited to conductive materials, no vacuum required, etc. It is widely used in the field of high-end precision manufacturing, especially in new energy vehicles and power battery industry.

 

From the manufacturing of lithium-ion battery cells to the assembly of battery packs, welding is a very important manufacturing process. The conductivity, strength, gas tightness, metal fatigue and corrosion resistance of lithium batteries are typical battery welding quality evaluation criteria... The choice of welding method and welding process will directly affect the cost, quality, safety and consistency of the battery. Next, we will take you through the various applications of laser welding systems in the field of lithium batteries.

 

Battery Blast Valve Welding

The explosion-proof valve of a battery is a thin-walled valve body on the battery's sealing plate. When the internal pressure of the battery exceeds a specified value, the explosion-proof valve body ruptures to prevent the battery from bursting. The safety valve has an ingenious structure and the process is extremely demanding on the laser welding process. Before continuous laser welding, the battery explosion-proof valve used pulse laser welding, through the lap and cover of the welded joints to achieve continuous sealing welding, but the welding efficiency is low, the sealing performance is relatively poor. Poor. Continuous laser welding can achieve high speed and high quality welding, and welding stability, welding efficiency and yield are guaranteed.

Cell welding

Tabs are usually divided into three materials. The positive electrode of the battery is made of aluminum (Al) material, and the negative electrode is made of nickel (Ni) material or copper-nickel plating (Ni-Cu) material. In the manufacturing process of power batteries, one of the steps is to weld the battery lugs and tabs together. In the production of secondary batteries, an additional aluminum safety valve needs to be welded. The welding must not only ensure a reliable connection between the pole lug and pole post, but also requires a smooth and beautiful weld.

 

Battery electrode strip spot welding

The materials used for battery electrode strips are pure aluminum strips, nickel strips, aluminum-nickel composite strips, and a small amount of copper strips. The welding of battery electrode strips is generally done by pulse welding machine. With the advent of IPG's QCW quasi-continuous laser, it is also widely used for battery electrode strip welding. At the same time, due to its good beam quality, the welding joints can be very small. It has unique advantages in handling welding of high reflectivity aluminum and copper strips and narrow strip battery electrode strips (strip width less than 1.5 mm).

 

Power battery shell and cover sealing welding

Power battery shell materials are aluminum alloy and stainless steel, of which aluminum alloy is most used, generally 3003 aluminum alloy, and a few use pure aluminum. Stainless steel is the best material for laser weldability. Both pulsed and continuous lasers can obtain welds with good appearance and performance. With continuous laser welding of thin-shell lithium batteries, the efficiency can be increased by 5 to 10 times, with better appearance and sealing performance. Therefore, there is a trend to gradually replace pulsed lasers in this application area.

 

Power battery module and PACK welding

Series-parallel connection between power cells is generally done by welding the connecting piece to the single cell. The materials of positive and negative electrodes are different. Generally speaking, there are two materials: copper and aluminum. Because copper and aluminum are laser welded, they form brittle compounds. To meet the application requirements, ultrasonic welding is usually used, and the welding of copper to copper and aluminum to aluminum is generally done by laser welding. Also, the very high thermal conductivity of copper and aluminum, the very high reflectivity of the laser, and the thickness of the joint require the use of higher power lasers to achieve the welding. This shows that laser welding stands out among the many welding methods. First of all, laser welding has high energy density, low welding deformation and small heat affected zone, which can effectively improve the accuracy of the parts. The weld seam is smooth and free of impurities, uniform and dense, without additional grinding work; secondly, laser welding can precisely control and focus the light. Small dot, high precision positioning, easy automation with robotic arm, improve welding efficiency, reduce man-hours and cost; in addition, laser welding of thin plates or fine diameter wire will not reflow as easily as arc welding. And it can be welded with a variety of materials, which can realize the welding between different materials.

 

Currently, the rapid development of new energy industry has driven the simultaneous growth of lithium-ion battery industry and lithium-ion battery equipment manufacturing industry, which provides a good ground for the large-scale application of laser cutting machine and laser cutting machine. welding machine and laser engraving machine for the lithium-ion battery market. It can be expected that with the continuous development of new energy market, the gradual improvement of quality requirements and the continuous improvement of laser technology, more laser cutting machines and laser welding machines can be applied to the lithium-ion battery market in the future, and more laser machine manufacturers can benefit from the lithium-ion battery industry.