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.
Pouch Side-Cut Degassing
Meaning
This essential manufacturing operation cuts open a temporary seal on a pouch cell to release gases generated during the formation cycle before resealing the cell permanently. Typically performed under vacuum in a dry environment, pouch side-cut degassing extracts the gases produced during the initial electrochemical charging of the cell. It ensures that the gas pocket, or gas bag, is removed and that the cell is compact, flat, and securely sealed for the rest of its life.
Sourcing managers evaluate the speed and precision of the degassing equipment to ensure high productivity and yield on the assembly line. If the degassing is not performed correctly, the residual gas will remain in the pouch, leading to poor heat transfer, cell swelling, and early failure.
Gas Extraction
The process starts after the cell has completed its formation cycles, which generate gases like carbon dioxide and carbon monoxide as the protective interphase forms on the anode. These gases collect in a specially designed extension of the pouch, known as the gas bag. The cell is placed in a vacuum chamber, where the gas bag is cut open, and the gas is drawn out under controlled pressure.
The edge is then thermally welded closer to the active stack, and the excess gas bag is cut off and discarded. This second and final seal must be hermetic and resistant to the electrolyte to ensure the cell’s long term stability.
Sourcing Considerations
Procuring the highly automated equipment needed for this process requires careful analysis of the cycle times, cutting precision, and vacuum control. Sourcing teams look for systems that minimize electrolyte loss and prevent the contamination of the weld area during the cutting and extraction phases. The contracts specify the maximum cycle time per cell and the acceptable yield rate, as this process is a major bottleneck in pouch cell assembly lines.
Suppliers must also guarantee the durability of the cutting blades and the reliability of the vacuum seals to prevent unexpected maintenance shutdowns.
Quality Control Impact
Sourcing agreements often define the acceptable residual gas volume and the required seal strength for the degassed cells. Quality engineers use non destructive tests, such as weight or thickness measurements, to ensure that the gas has been fully extracted and that the final seal is secure. Sourcing teams audit these quality metrics to verify that the manufactured cells meet the warranty standards of the final application.
This process is critical for delivering high performance, swell resistant pouch cells to the market.