Lithium Battery Sealing Rivets Laser Welding Solution By HW-Laser Welding Technology

Sealing rivets (also termed battery plugs or sealing nails) are critical components in lithium-ion battery manufacturing. They permanently seal the electrolyte filling port after liquid injection, ensuring hermetic isolation of the cell's internal environment from external contaminants. Their design integrates mechanical stability, electrochemical inertness, and safety functions.

1. Aluminum Alloys (1060/3003)​: Dominant material (thickness: 0.08–0.1 mm) due to high ductility, lightweight properties, and compatibility with laser welding. Pure aluminum resists electrolyte corrosion but faces challenges like high infrared laser reflectivity (>90%).
2. Composite Designs: Advanced rivets combine metal (e.g., stainless steel) with thermoplastic vulcanizate (TPV) or fluoropolymer seals. The TPV layer creates a secondary sealing flange that blocks electrolyte penetration into weld seams, enhancing longevity.

• Compatibility with High-Reflectivity Materials:

  Superior energy absorption for Al/Cu alloys—60–70% in keyhole vs. 10% for traditional lasers. Ideal for sealing rivets and battery shells.

• Reduced Thermal Deformation:

  Low heat input (±5% fluctuation control) prevents warping of thin Al lids, ensuring flatness <0.1 mm deviation

Laser welding uses high-energy beams (typically 1,070 nm fiber lasers) to fuse the sealing rivet to the battery casing (usually aluminum or steel). This replaces mechanical crimping or adhesive bonding, achieving atomic-level metallurgical bonds.

1. Dual-Spot Technology: Combines inner-ring and outer-ring beams. Minimizes heat-affected zones (HAZ) while ensuring 0.6 mm uniform weld depth.
2. Waveform Modulation: Pre-peak + exponential decay waveforms overcome aluminum's reflectivity, boosting energy absorption by 40%.
3. Multi-Stage Welding: Pre-tack welding (≥4 symmetric points) → segmented full welding → vent-hole sealing (for gas-managed rivets).

Combines a central high-intensity beam (for deep penetration) and an outer ring beam (for molten pool stabilization). This design enables precise heat distribution, reducing thermal stress on thin Al sealing rivets (0.08–0.1 mm) and minimizing defects like cracks or blowholes.

Lithium battery sealing rivets evolve beyond simple plugs into integrated safety systems, leveraging aluminum alloys and composite designs for hermeticity and pressure management. Laser welding enables precision sealing with advantages in speed, quality, and material efficiency. Dual-beam optics, adaptive waveforms, and AI-driven process control resolve thin-Al welding challenges, while inline inspection ensures zero-defect outputs. As sodium and solid-state batteries advance, sealing technologies will prioritize higher rupture pressures and ceramic compatibility, with laser welding remaining the benchmark for high-volume, reliable production.

1. Anti-Spatter Mechanism:

   The ring beam suppresses metal vapor ejection by stabilizing the keyhole, reducing spatter by >95% compared to single-beam lasers. Critical for avoiding electrode contamination and short circuits in batteries.

2. Near-Zero Spatter Welding:

   Achieves smooth, fish-scale-like welds with no visible spatter or pores (see Figure 1). Eliminates post-weld cleaning and reduces maintenance downtime by 40%.

3. High-Speed Processing:

   Enables welding speeds up to 300 mm/s while maintaining 0.6 mm penetration depth and 1.2 mm weld width. Increases production efficiency to 50–60 PPM (parts per minute) .

4. Enhanced Sealing Integrity:

   Reduces porosity to <0.1% and ensures helium leak rates ≤1*10⁻⁹ Pa·m³/s, meeting strict hermeticity standards.

5. Electrolyte Contamination Tolerance:

   Tolerates residual electrolyte crystals in the liquid-filling port. The ring beam’s preheating effect prevents explosive gas formation during welding, reducing blowhole defects by 90%.