Winding / Stacking in Lithium-Ion Pouch Cell Manufacturing

After electrode slitting, the next major assembly step is Winding or Stacking. The process precisely combines anode, separator, and cathode layers to create the internal electrochemical structure of the cell.

Purpose of Winding / Stacking

The main objective is to arrange electrode and separator layers in the correct sequence while maintaining dimensional accuracy and electrical isolation between the positive and negative electrodes.

Winding Process

In a winding design, electrode and separator materials are fed under controlled tension and wound into a compact structure commonly called a Jelly Roll (JR).

Controlled material feeding
Accurate layer alignment
Stable winding tension
Controlled winding speed
Proper termination and securing

Stacking Process

In a stacking design, individual electrode and separator sheets are placed in a controlled sequence to form a layered electrode stack.

Anode placement
Separator placement
Cathode placement
Repeated layer formation
Final alignment and pressing

Critical Quality Parameters

Electrode alignment
Separator alignment
Winding or stacking tension
Layer count
Tab position
Final thickness and geometry

Common Defects

Electrode misalignment
Separator offset
Wrinkles
Telescoping or layer shift
Tab-position variation
Foreign-particle contamination

Quality Impact: Defects at this stage can influence capacity, internal resistance, electrical isolation, sealing alignment, and long-term cycle performance.

Conclusion

Winding and stacking build the core internal structure of the lithium-ion cell. Precise alignment, tension control, cleanliness, and dimensional monitoring are essential for reliable cell assembly.

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