The tab serves as the final current-carrying element in this path. Its current-carrying capacity is therefore a critical factor that affects both electrical efficiency and thermal stability. Any limitation in tab conductance can result in increased ohmic losses, localized heating, and potential degradation of cell lifetime and safety.
Tab Materials and Current Flow in Li-Ion Cells
While not shown in the figure, clad tab materials are increasingly used in modern cells. Because nickel has relatively low conductivity, higher-conductivity solutions are needed in limited space to enable high-power and energy-dense cells. As a result, sandwich-like or two-layer combinations of nickel and copper are commonly employed in high-performance cells.
Tabbed vs Tabless Cylindrical Cells
Tabless Design – Pros
- Lower internal resistance
- Reduced heat generation
- Higher energy density
- Improved power capability
- Potentially simpler thermal management
Tabless Design – Cons
- More complex manufacturing
- Higher initial production cost
Tab position changes what the best electrode shape is. Tab crowding limits how wide a cell can usefully get, while the foil path limits how tall it can get. Putting the tabs on opposite edges doesn’t cut foil resistance, but it spreads the current much more evenly, which matters more for lithium plating.
See also: Why Do Wound Cells Typically Have Higher Internal Resistance Than Z‑Stack Cells?