Cutting & Folding Defects in Li-ion Pouch Cell Manufacturing

In lithium-ion pouch cell production, the cutting and folding stage prepares the aluminum laminate pouch before jelly roll insertion. During this stage, the laminate undergoes operations such as pocket cutting, folding, and top cutting to create the required pouch structure.

Even small deviations during these operations can affect sealing area, dimensional accuracy, and the mechanical strength of the pouch. If defects are not detected early, they may propagate into later stages such as sealing, electrolyte filling, and formation.

Key Cutting & Folding Related Defects

1. Burr on Edge

Burrs are small rough edges or projections created during cutting. They are commonly associated with worn cutting tools or incorrect blade clearance. These sharp edges can damage the sealing layer and increase the risk of leakage during subsequent sealing operations.

2. Uneven Pocket Cutting

If the cutting process is not correctly aligned, pocket edges can become uneven. This creates dimensional variation and can affect pouch symmetry and sealing accuracy.

3. Pocket Folding Defect

Incorrect folding pressure or misaligned folding tools can produce improper folds in the laminate. Such defects may create localized stress points and weaken the pouch structure.

4. Incomplete Fold

An incomplete fold occurs when the intended folding operation does not fully form the required structure. Insufficient pressure, incorrect tool alignment, or process variation can contribute to this defect and may later create sealing difficulties.

5. Top Cut Height Variation

Variation in top-cut height can produce inconsistent sealing areas. It may also affect tab clearance and increase the possibility of sealing-related defects.

6. Edge Crack

Cracks along the cut edge can develop because of excessive mechanical stress, improper tooling, or brittle laminate material. These cracks may propagate during sealing or later cell operation.

7. Corner Damage

Corners experience relatively high mechanical stress during cutting and folding. Improper tooling or misalignment can result in corner deformation or tearing.

Why These Defects Matter

Cutting and folding defects may appear minor, but they directly influence pouch dimensional accuracy and sealing quality.

If not properly controlled, they can result in:

• Weak or inconsistent sealing
• Pouch leakage during electrolyte filling
• Mechanical failure during formation
• Reduced production yield
• Reduced product reliability

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