r03 battery.Introduction to laser processing and welding technology in lithium battery manufacturing equipment

　　Introduction to laser processing and welding processes in lithium battery manufacturing equipment. Laser welding has become the preferred solution for many welding tasks due to its advantages such as safe and reliable welding, precision technology, and environmental protection. Lithium battery manufacturing equipment generally includes three types: front-end equipment, mid-end equipment, and back-end equipment. The accuracy and automation level of the equipment will directly affect the production efficiency and consistency of the product. As an alternative to traditional welding technology, laser processing technology has been widely used in lithium battery manufacturing equipment.

　　Laser welding is an important process for lithium battery processing and manufacturing

　　Laser welding process has become an important process in lithium battery manufacturing. Laser welding is the only non-contact, high-precision and efficient welding method; it can weld and seal battery structural parts economically and quickly. Laser processing usually includes laser cutting, laser welding, laser surface treatment, etc.

　　In the entire power lithium battery manufacturing, including cells, modules and packs, there are about 19 main component parts that need to be welded. Among them: 11 welds currently must be laser welded; 5 welds may use laser welding; 3 welds cannot be used. Laser welding will be used. In square case batteries, sealing nails, cover components and seals all require laser welding; in cylindrical batteries and modules, the parts that require laser welding include tabs, caps, busbars, etc.

　　Laser welding quality improvement and testing. In terms of module side plate welding, power lithium battery modules commonly use aluminum alloy profiles and plates as module outer frame structural parts. The quality of the welding determines the rigidity of the overall module structure. Different welding effects can be obtained by using different welding heads and processes. A variety of process methods have also been developed for side plate laser welding. The porosity of ordinary welding joints reaches 10%, the porosity of double-beam welding joints is 3%, and the porosity of swing spot welding joints is only 1%. More and more advanced laser welding equipment and processes are constantly improving welding quality and reducing porosity.

　　In addition, cell sealing laser welding is an important process in lithium battery processing and manufacturing, which greatly affects the battery yield. While the welding speed of battery cores is getting faster and faster, welding performance such as weld consistency must also be ensured. A variety of laser welding sealing processes are derived from this. Among them, fiber laser uses high-speed swing welding to make the welds flat and smooth with good consistency. As the welding frequency increases, the swing head has a repairing effect on the explosion point.

　　Lithium battery processing laser welding process

　　From the manufacture of lithium battery cells to the assembly of battery packs, welding is a very important manufacturing process. The conductivity, strength, air tightness, metal fatigue and corrosion resistance of lithium batteries are typical battery welding quality evaluation standards. . The selection of welding methods and welding processes will directly affect the cost, quality, safety and consistency of lithium batteries.

　　Among many welding methods, laser welding for lithium battery processing stands out with the following advantages: First, laser welding has high energy density, small welding deformation, and small heat-affected zone, which can effectively improve the accuracy of parts. The welds are smooth, impurity-free, uniform, and dense. No additional grinding work is required; secondly, laser welding can be precisely controlled, with a small focused light spot and high-precision positioning. It can be easily automated with a robotic arm, improving welding efficiency, reducing working hours, and reducing costs; in addition, laser welding of thin plates or thin-diameter wires When used, it is not as susceptible to meltback as arc welding.

　　The advantage of laser welding lies in the wide range of materials that can be welded, and the ability to weld different materials. During the welding process of power lithium batteries, welding process technicians will select the appropriate laser and welding process parameters based on the battery material, shape, thickness, pulling force requirements, etc., including welding speed, waveform, peak value, welding head tilt angle, etc. to set a reasonable Welding process parameters to ensure that the final welding effect meets the requirements of power battery manufacturers.

　　Application of laser welding in lithium batteries

　　1. Battery explosion-proof valve welding

　　The explosion-proof valve of the battery is a thin-walled valve body on the battery sealing plate. When the internal pressure of the lithium battery exceeds the specified value, the explosion-proof valve body ruptures to prevent the battery from bursting. The safety valve has an ingenious structure, and this process requires extremely strict laser welding processes.

　　2. Battery tab welding

　　The tabs are usually divided into three materials. The positive electrode of the battery uses aluminum (Al) material, and the negative electrode uses nickel (Ni) material or copper-plated nickel (Ni-Cu) material. In the manufacturing process of power batteries, one of the steps is to weld the lithium battery tabs and poles together. In the production of secondary batteries, it needs to be welded with another aluminum safety valve. Welding must not only ensure a reliable connection between the tab and the pole, but also requires the weld to be smooth and beautiful.

　　3. Battery poles with spot welding

　　The materials used for battery pole strips include pure aluminum strips, nickel strips, aluminum-nickel composite strips, and a small amount of copper strips. Pulse welding machines are generally used to weld battery pole strips. With the emergence of IPG's QCW quasi-continuous laser, it has also been widely used in lithium battery pole strip welding.

　　Laser welding is currently the main method recommended for high-end lithium battery welding. Laser welding is a process in which a high-energy beam of laser irradiates the workpiece, causing the working temperature to rise sharply, melting the workpiece and reconnecting to form a permanent connection.

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