FQI (Final Quality Inspection) in Lithium-Ion Pouch Cell Manufacturing

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FQI (Final Quality Inspection) in Lithium-Ion Pouch Cell Manufacturing

FQI is the final major quality-control gate before a lithium-ion pouch cell proceeds to final inspection, packaging, and dispatch. It combines visual, dimensional, electrical, and traceability checks to verify that the cell meets its defined requirements.

Purpose of FQI

  • Verify overall cell quality
  • Detect defects that may have passed earlier stages
  • Confirm compliance with specifications
  • Prevent non-conforming cells from reaching customers

Key Inspection Areas in FQI

1. Visual Inspection

Cells are checked for surface scratches, laminate wrinkles, seal defects, contamination, corner damage, and other visible abnormalities.

2. Dimensional Inspection

Critical dimensions are verified using CCD systems or gauges. Typical parameters include cell length and width, sealant height, tab distance, degassing-side dimensions, and corner geometry.

3. Electrical Testing

  • OCV verification
  • Internal resistance measurement
  • Hi-Pot insulation testing

4. Barcode Verification

Barcode presence, data accuracy, and readability are checked so that the cell remains fully traceable through production and supply-chain systems.

Critical Process Parameters

  • Inspection accuracy
  • Calibration of measurement equipment
  • Clearly defined acceptance and rejection criteria
  • Proper operator training for manual checks

Common Defects Identified in FQI

  • Weak sealing, wrinkles, or seal misalignment
  • Cell dimensions or tab positions outside specification
  • Abnormal OCV or high internal resistance
  • Scratches, dents, or laminate defects
  • Missing or unreadable barcode
Why it matters: Missing a defect at FQI can contribute to customer complaints, field failures, safety incidents, and additional warranty costs.

Conclusion

FQI provides a comprehensive final check of the mechanical, electrical, visual, and traceability condition of the pouch cell. A well-controlled FQI process helps ensure that only cells meeting the required specifications move toward final release.

#BatteryManufacturing #FQI #LithiumIonBattery #PouchCell #QualityControl #BatteryEngineering #EVBattery

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