Degassing in Lithium-Ion Pouch Cell Manufacturing

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Degassing in Lithium-Ion Pouch Cell Manufacturing

After activation or formation, the pouch cell undergoes degassing to remove gases generated during the initial electrochemical reactions. Proper gas removal is important for cell stability, safety, and final pouch geometry.

Why Gas is Generated During Formation

During the initial charge and discharge cycles, side reactions occur inside the cell. These reactions can generate gases such as carbon dioxide, carbon monoxide, hydrogen, and other organic gases. If retained, the gases can increase internal pressure and cause swelling.

Purpose of Degassing

  • Remove gases generated during formation
  • Reduce internal pressure
  • Improve pouch-cell stability
  • Prepare the cell for final sealing

Degassing Process Sequence

  1. The formed cell is transferred to the degassing station.
  2. The pouch is positioned and connected to the degassing system.
  3. The temporary gas-containing region is opened or processed according to the equipment design.
  4. Vacuum is applied to remove accumulated gases.
  5. The cell is resealed after gas removal.
  6. The resealed area is inspected.

Common Degassing Issues

  • Incomplete gas removal
  • Improper vacuum conditions
  • Seal damage during resealing
  • Excessive pouch deformation
  • Residual gas leading to swelling
Critical Controls: Vacuum level, dwell time, pouch positioning, resealing parameters, and leak/seal inspection should be controlled consistently.

Importance in Cell Quality

Improper degassing can contribute to swelling, leakage, dimensional problems, and long-term reliability issues. For this reason, degassing is a sensitive transition between formation and final pouch finishing.

Conclusion

Degassing removes formation-generated gases and prepares the pouch cell for stable final processing. Accurate vacuum control and reliable resealing are essential to maintain pouch integrity.

#Degassing #BatteryManufacturing #LithiumIonBattery #PouchCell #BatteryEngineering #EVBattery

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