Insulating tapes for lithium cells
PET and polyimide tapes are used to wrap lithium battery cells and insulate the electrodes from the casing, and they must also withstand electrolyte in case of leakage during production or operation.
On a battery cell, tape appears in more places than most people think: wrapped around the electrode jelly roll, securing tab ends, wrapping cylindrical cell bodies and insulating the top of prismatic cells. Each location has its own requirements for the backing material and adhesive layer.
Where tape is used in a battery cell
- Jelly roll termination tape: keeps the electrode roll from unwinding after winding and sits in the electrolyte environment.
- Tab protection tape: covers the cut edges of the electrode foil, preventing metal burrs from puncturing the separator.
- Cell wrap tape: insulates the cell casing from adjacent cells and from the module frame.
- Top cover tape: insulates between the terminals and the busbar.
PET or polyimide
| Property | PET tape | Polyimide tape |
|---|---|---|
| Operating temperature | Up to approx. 130 °C | Up to approx. 260 °C |
| Typical thickness | 25 – 75 µm | 25 – 60 µm |
| Dielectric strength | Approx. 5 – 7 kV | Approx. 6 – 8 kV |
| Cost | Low | Several times higher |
| Typical application | Cell wrapping, top cover | Tab protection, areas near welds |
For locations inside the cell, the adhesive is usually a specialty acrylic or rubber that has been tested by immersion in LiPF6 solution at 60 °C for many days without peeling or leaching impurities.
Inspection criteria for sample approval
Beyond peel strength and dielectric strength, cell plants typically require measurement of metal ion content, roll moisture content and confirmation that the tape does not discolor the electrolyte. Cell wrap tape is also tested for scratch resistance as cells rub against each other during transport.
Recommendations for automated lines
Tape should unwind with consistent tension, with cores that match the taping machine standard and clean slit edges free of adhesive strings. AMS can slit rolls to widths from 3 mm and die-cut labels on liners to suit automatic taping machines.
The AMS warehouse stores battery-industry tapes in a temperature- and humidity-controlled area, with rolls packed in moisture-barrier bags with desiccant. This is especially important for tapes used in dry rooms, where the moisture content of every incoming material is tightly controlled. Every carton is clearly labeled with the lot number and production date for easy traceability.
Contact AMS Vietnam to request samples of insulating tapes for battery cells and detailed specification sheets.
