How to optimize the strength and conductivity of welded joints in laser welding machine for supercapacitor?
Publish Time: 2025-02-28
The performance of cylindrical batteries directly affects the safety, efficiency and life of battery packs, among which welding quality is a key factor. Laser welding technology has become a commonly used welding method in cylindrical battery manufacturing due to its precision, efficiency and flexibility. However, how to optimize the strength and conductivity of welded joints in the laser welding machine for supercapacitor process has always been a core issue for improving battery performance and safety.
1. Welding parameter optimization of laser welding machine
The strength and conductivity of welded joints are closely related to the parameters used in the laser welding process. The following are some important welding parameters that have a significant impact on the strength and conductivity of welded joints:
Laser power: Appropriate laser power helps ensure welding depth and welding strength. Too low power may result in insufficient welding and insufficient joint strength; too high power may cause overheating, form irregular molten pools or damage the material in the welding area. By accurately adjusting the laser power, a good welded joint can be obtained.
Welding speed: Too fast welding speed may result in incomplete fusion of the welded joint, which in turn affects the weld strength. If the welding speed is too slow, it may cause overheating, increase the stress in the welding area, and affect the conductivity. The ideal welding speed can ensure the appropriate molten pool, strength and conductivity.
Focus position and spot size: The focal position and spot size of the laser beam have an important influence on the welding quality. Accurate focus control can ensure the concentration of the laser beam, provide stronger heat input, and make the welded joint have better strength and conductivity. Reasonable selection of spot size also helps the stability of the molten pool and avoids excessive heat-affected zones.
2. Selection and processing of welding materials
Different materials have different welding characteristics, so choosing the right welding material is crucial to improving the strength and conductivity of the welded joint. The welding of cylindrical batteries generally uses nickel, copper, aluminum and other materials. The conductivity, thermal conductivity and welding performance of these materials need to be considered.
Nickel material: Nickel is usually used for welding battery electrodes. Its excellent conductivity ensures the conductivity of the welded joint. In order to improve the welding strength, nickel alloys can be used to enhance the toughness of the welded area.
Copper material: Copper has very good conductivity and is often used in the connection part of the battery. Copper welding is difficult, and requires precise control of welding temperature and laser power to avoid oxidation or thermal deformation of copper caused by overheating.
Aluminum material: Aluminum alloy has good lightweight properties, but it is easy to produce an oxide layer during welding, which affects the welding quality. Laser welding pretreatment (such as aluminum surface cleaning) is usually required to remove the oxide layer to improve the conductivity and strength of the joint.
3. Cooling and heat treatment of welded joints
During the welding process, excessive heat input will cause uneven heating of the material, resulting in a decrease in the strength and conductivity of the welded joint. Therefore, reasonable cooling and heat treatment are very important. The cooling process can not only avoid excessive heat-affected zones, but also help the welded joint form a uniform organizational structure and improve its mechanical properties and conductivity.
Rapid cooling: Rapid cooling can avoid grain coarsening in the welded joint area and maintain the strength and conductivity of the joint. Especially for highly conductive metal materials, rapid cooling can reduce their thermal deformation and improve the electrical contact performance of the welded joint.
Post-heat treatment: Some welded joints need to be heat treated after welding to further improve the grain structure of the joint and enhance the toughness and conductivity of the joint. Especially for materials such as copper or nickel, their conductivity and durability can be improved through proper heat treatment.
4. Heat input and stress control of laser welding
During laser welding, the size of heat input directly determines the structure and performance of the welded joint. Excessive heat input will cause the material around the welded joint to overheat, which will then generate internal stress, affect the strength of the joint, and may cause cracks or fatigue damage. Therefore, controlling the heat input during welding and reducing the internal stress generated during welding are the key to improving welding strength and conductivity.
Optimizing heat input: Reasonable selection of a combination of laser power and welding speed can avoid excessive heat input, thereby reducing the heat-affected zone of the welded joint, maintaining joint strength and improving conductivity.
Controlling the heat-affected zone: The size and shape of the heat-affected zone determine the mechanical and electrical properties of the joint. A smaller heat-affected zone usually means stronger joint strength and better conductivity, so it is necessary to accurately control the temperature distribution during laser welding.
5. Microstructure optimization of welded joints
The microstructure of welded joints has an important influence on their conductivity and strength. During laser welding, solid phase transformation, phase precipitation and grain growth in the joint area will affect the performance of the joint. By optimizing the welding process, especially controlling the welding temperature and cooling rate, the microstructure of the welded joint can be effectively optimized, and the conductivity and mechanical properties of the joint can be improved.
Grain refinement: Fine grains can improve the strength and toughness of the joint and avoid brittleness caused by large grains. By reasonably controlling the welding temperature and cooling rate, the uniform distribution of grains in the welded joint can be promoted, thereby optimizing the microstructure of the welded joint.
The optimization of the strength and conductivity of the welded joint of the laser welding machine for supercapacitor involves multiple factors, including laser welding parameters, welding material selection, heat input control, cooling process and microstructure optimization of the welded joint. By precisely controlling the laser power, welding speed and focus position, the strength of the welded joint can be effectively improved, the heat-affected zone can be reduced, and the conductivity of the joint can be optimized, thereby improving the performance and service life of the cylindrical battery.
