Helium Mass Spectrometry for Micro Leak Detection in Battery Envelopes
Inline helium mass spectrometry detects sub-micron battery envelope leaks down to 10-8 mbar l/s, preventing moisture-induced HF corrosion and solvent loss.
Prismatic Laser Weld
Meaning
High-density energy beams melt and join the metallic interfaces of battery housings to create a hermetic seal. The prismatic laser weld is the primary method used to attach the aluminum cover plate to the deep-drawn can of a prismatic cell. This continuous joint must resist high internal pressure and prevent any leakage of volatile electrolyte solvent during the vehicle service life.
Because it involves complex material interactions between different aluminum alloys, process control is critical to prevent micro-cracks and ensure the structural integrity of the cell casing.
Manufacturing Process
The assembly process uses a fiber laser to deliver precise heat to the butt joint between the cover and the cell can. This rapid heating and cooling cycle minimizes the heat-affected zone, protecting the sensitive internal active materials from thermal damage. Precise control of the laser power and welding speed is required to avoid pinholes.
Quality Verification
Online sensor systems monitor the light emissions and acoustic signatures generated during the melting process. If a discrepancy in the energy density occurs, the joint is flagged for manual inspection. After welding, the cell undergoes helium leak testing to verify the hermeticity of the seal.
Operational Safety
An imperfect weld can crack under the mechanical stress caused by cell swelling during charging. This failure allows moisture to enter and react with the electrolyte, creating corrosive acids and gases. Sourcing specifications enforce strict quality limits on weld penetration and porosity to avoid such field failures.