Precautions and Key Points for Laser Welding of Lithium Battery Tabs
Laser welding of lithium battery tabs requires careful consideration of the laser welder type, process characteristics, and material properties. For copper and aluminum tabs, specific laser types like MOPA fiber lasers or picosecond lasers are recommended due to their unique properties. Key parameters such as wavelength, power, and pulse width must be precisely set to ensure welding quality. Process control, including automation, pre-welding preparation, and post-welding inspection, is essential. Material thickness, cleanliness, and the heat-affected zone also significantly impact welding outcomes. Proper selection and control of these factors are crucial for achieving high-quality, reliable welds in lithium battery production.
Precautions and Key Points for Laser Welding of Lithium Battery Tabs
I. Laser Welder
1. Selection of Laser Welder Type
The choice of laser welder type is crucial based on the tab material. The following table shows the recommended laser welder types and their characteristics for different tab materials:
| Tab Material | Recommended Laser Welder Type | Characteristics |
|---|---|---|
| Negative electrode copper foil of lithium battery | 1064nm MOPA fiber laser | High peak power density (2.4×10⁶W/mm²), capable of “narrow pulse width” cutting through electrical modulation, suitable for copper foil welding |
| Positive electrode aluminum foil of lithium battery | Pulsed laser with picosecond pulses | Achieves ultra-narrow pulse signals using third-harmonic generation technology, suitable for high-reflectivity aluminum foil welding |
2. Laser Welder Parameter Settings
The proper setting of laser welder parameters is key to ensuring welding quality. The following table lists common laser welder parameters and their typical values:
| Parameter | Typical Value | Description |
|---|---|---|
| Wavelength | 1064nm | Suitable for most metallic materials |
| Power | 110W–200W | Adjusted according to tab material and thickness |
| Spot Diameter | 28μm | Adjustable according to welding requirements |
| Scanning Speed | 500mm/s | Controls welding speed, affecting weld seam quality |
| Pulse Frequency | 200kHz | Controls pulse repetition rate |
| Pulse Width | 50–120ns | Controls the energy of a single pulse |
3. Stability Requirements of Laser Welder
The stability of the laser welder directly affects welding quality. The following table shows the specific stability requirements for laser welders:
| Requirement | Description | |
|---|---|---|
| Beam Mode | Fundamental mode (TEM00) or low-order mode | Ensures good beam focusing performance, achieving high power density and large weld seam depth-to-width ratio |
| Output Power Stability | ±1% | Ensures stable welding process, avoiding welding defects caused by power fluctuations |
II. Process Characteristics
1. Welding Methods
The choice of welding method depends on welding requirements and material properties. The following table shows two common welding methods and their characteristics:
| Welding Method | Characteristics | Application Scenarios |
|---|---|---|
| Pulsed Welding | Forms single or multiple rows of weld spots, controls welding energy, reduces heat input | Suitable for thin materials or applications requiring low heat input |
| Continuous Welding | Smooth and uniform weld seam surface, no spatter, no defects, no internal cracks, high production efficiency | Suitable for materials like aluminum alloy, ideal for mass production |
2. Welding Process Control
Strict control of the welding process is crucial for ensuring welding quality. The following table lists the key control points in the welding process:
| Control Aspect | Specific Requirements |
|---|---|
| Degree of Automation | Automated loading, welding, inspection, and unloading to reduce human error |
| Pre-welding Preparation | Tab pressing to ensure tight contact at the welding site |
| Welding Parameters | Control welding speed, power, focus position, etc., to ensure welding quality |
| Post-welding Inspection | Inspect weld points to ensure no virtual welding or missed welding defects |
3. Use of Shielding Gas
Shielding gas plays an important role in laser welding. The following table shows the types of shielding gases and their functions:
| Shielding Gas | Function |
|---|---|
| Argon | Prevents oxidation of the workpiece during welding, protects the focusing lens from contamination |
| Helium | Disperses plasma, increases penetration depth |
III. Material Characteristics
1. Tab Materials
The properties of tab materials directly affect the welding process and parameter selection. The following table shows the characteristics of different tab materials and welding considerations:
| Material Type | Characteristics | Welding Considerations |
|---|---|---|
| Copper Tab | Good electrical and thermal conductivity, but high laser reflectivity | Choose appropriate laser wavelength and power to avoid reflectivity losses |
| Aluminum Tab | High laser reflectivity | Adjust the tilt angle of the laser welder to increase weld seam penetration and width |
2. Material Thickness
Material thickness is an important factor affecting welding parameters. The following table shows the thickness range and corresponding welding parameter adjustments:
| Thickness Range | Typical Value | Welding Parameter Adjustments |
|---|---|---|
| Tab Thickness | 0.2–0.6mm | Adjust laser power and pulse width according to thickness |
3. Material Cleanliness
The cleanliness of the tab surface is crucial for welding quality. The following table shows the cleanliness requirements and description:
| Cleanliness Requirement | Description |
|---|---|
| Surface Cleanliness | Free of oil, dust, and other impurities, otherwise it will affect welding quality and strength |
4. Heat-Affected Zone of Material
The size and characteristics of the heat-affected zone can affect the material properties after welding. The following table shows the characteristics of the heat-affected zone and description:
| Characteristic | Description |
|---|---|
| Small Heat-Affected Zone | The heat-affected zone is small during the welding process, but welding parameters need to be controlled to reduce heat input and avoid material deformation |
The above content integrates detailed explanations of laser welders, process characteristics, and material characteristics, and clearly presents key information in tabular form to help better understand and apply lithium battery tab laser welding technology.