Moisture Control from Electrolyte Fill to Export Container
Electrode vacuum baking below 15 ppm residual water prevents hydrofluoric acid formation during electrolyte filling, preserving cell cycle life and landed margin.
Prismatic Header Laser Weld
Meaning
This high precision manufacturing process uses a focused laser beam to seal the top cover, or header, to the metal can of a prismatic battery cell. Typically applied in the assembly of lithium ion cells with aluminum or steel cases, the prismatic header laser weld creates a strong, hermetic, and leak proof joint. It provides a secure seal that prevents the escape of volatile organic solvents and protects the cell from moisture ingress.
Sourcing managers analyze the welding speed, the joint quality, and the defect rates to evaluate the capability and efficiency of the assembly line. If the weld is defective, it can result in electrolyte leakage, microcracks, and safety hazards during cell operation.
Welding Mechanics
The process utilizes a fiber or disk laser that is directed along the joint between the cell cover and the can. The laser beam melts the metal at the interface, which solidifies rapidly to form a continuous and uniform weld seam. This process must be performed with high speed and precise power control to minimize the heat input into the cell, which could damage the sensitive internal components and plastic seals.
Advanced monitoring systems, such as optical coherence tomography or melt pool cameras, are used to inspect the weld in real time. Sourcing specifications require the weld to be completely free of pinholes, cracks, and spatters to ensure cell reliability.
Sourcing Requirements
Procuring the welding equipment and the matching cell cans and headers requires close coordination between sourcing, engineering, and quality teams. The contracts specify the dimensional tolerances of the cans and headers, as any gaps between them can lead to incomplete welds or burn through. Sourcing teams evaluate the laser source, the beam delivery system, and the integration of the automated fixtures that hold the cell assembly in place.
The agreements often include provisions for cycle times, machine yield, and the availability of spare parts to ensure continuous production.
Quality Assurance
Sourcing contracts define the testing protocols for verifying the weld integrity, which include helium leak testing and pressure burst tests. The weld must be able to withstand the high internal pressures that can build up during normal and abnormal cell operation. Any failure in the weld can lead to cell degradation, loss of performance, or safety issues.
By enforcing these rigorous quality requirements, sourcing departments ensure that the purchased cells will be durable and safe for use in demanding applications.