In Z‑stack (stacked) cell architectures, electrodes are cut into individual sheets and stacked layer‑by‑layer. The separator is a continuous “Z” interlayer. Each anode and cathode sheet typically has its own dedicated tab or very short current‑collection distance.
This configuration provides several electrical advantages:
- Minimal current path length from active material to tab
- Highly uniform current distribution
- Significantly reduced ohmic resistance (R_ohmic)
Because electronic current reaches the tabs almost immediately, stacked cells naturally exhibit lower internal resistance, especially under high‑power operation. This is one of the key reasons stacked pouch and prismatic cells are preferred in applications demanding high power density and thermal uniformity.
Advanced Z Stacking
LG Energy Solution’s proprietary improvement on the basic Z-stacking electrode assembly method used in pouch-type lithium-ion batteries. It merges the traditional Z-stacking approach—where cathode and anode sheets are alternately layered with the separator in a zigzag pattern—with LG’s own Lamination & Stacking (L&S) technology and a heat-press bonding step to deliver enhanced safety, alignment precision, and manufacturing efficiency.
Why Do Wound Cells Typically Have Higher Internal Resistance Than Z‑Stack Cells?
In lithium‑ion battery design, internal resistance is one of the most critical parameters governing power capability, heat generation, fast‑charge performance, and overall efficiency. The difference in internal resistance between wound (spiral/jelly‑roll) cells and Z‑stack (stacked) cells is often misunderstood as a chemistry issue, while in reality it is largely a current‑path and cell architecture problem.