Background: Pouch cell tabs provide the electrical pathway between the internal current collectors and the external cell terminal while also forming part of the pouch seal interface. Avocet Research Centre (ARC) was approached by a battery manufacturer to assess whether tab material, surface condition and seal compatibility could be improved for cells using a bespoke electrolyte formulation with application-specific chemical and operating requirements.
Challenge: The technical challenge was not simply to improve “lead tabs”, but to specify a tab construction that balanced corrosion resistance, electrical conductivity, weldability, polymer adhesion and pouch-seal integrity in contact with the customer’s electrolyte. The work also needed to distinguish between the positive and negative tab requirements, where aluminium, nickel, or nickel-plated copper options can behave differently under electrochemical exposure and during cell assembly.
Solution: ARC carried out a structured materials and validation programme focused on tab construction, surface preparation and electrolyte compatibility. The work combined materials selection, surface treatment assessment, seal-interface evaluation and electrochemical testing to identify a technically robust solution for the customer’s cell design.
- Tab Material Selection: Candidate tab materials assessment considered aluminium, nickel, and nickel-plated copper options.
- Surface and Seal Interface Treatment: Surface treatments and coating approaches were assessed for their ability to improve corrosion resistance and polymer adhesion at the tab-to-pouch seal interface. Particular attention was given to maintaining chemical stability without compromising weld quality or electrical performance.
- Electrolyte Compatibility Testing: Selected tab variants were exposed to the bespoke electrolyte under defined temperature and time conditions. Testing focused on corrosion behaviour, visual and microscopic surface change, seal integrity and any measurable resistance increase after exposure.
- Electrochemical and Mechanical Validation: ARC used electrochemical screening and mechanical checks to confirm whether the preferred tab construction remained stable under representative operating conditions. The validation focused on corrosion tendency, contact resistance, adhesion performance and the robustness of the tab during assembly handling.
Results: The revised tab construction and surface preparation route provided clearer compatibility with the customer’s electrolyte and reduced the main technical risks associated with corrosion, seal degradation and resistance increase.
- Improved corrosion resistance: The preferred material and surface condition reduced visible degradation after electrolyte exposure, supporting longer-term chemical stability at the tab surface.
- More robust seal interface: The optimised surface and polymer interface improved confidence in pouch-seal performance, reducing the risk of electrolyte leakage or bond failure during cell life. Polymer seal adhesion retention increased from the industry minimum standard of ~1 N/mm to >2 N/mm.
- Controlled electrical performance: Electrical performance was maintained by balancing corrosion protection with low-resistance current transfer and compatibility with the selected welding process.
- Reduced integration risk: The work gave the customer a clearer specification basis for tab material, surface treatment and seal selection before committing to further cell build activity.
Conclusion: The programme demonstrated how tab reliability depends on the combined behaviour of material selection, surface condition, electrolyte exposure and seal-interface performance. By treating the tab as an integrated electrochemical and mechanical component rather than a simple connector, ARC helped the customer reduce technical uncertainty and move towards a more reliable pouch cell design.