Background: ARC undertook a feasibility study to develop titanium lead tabs for pouch cell applications where chemical compatibility, corrosion resistance and seal integrity were critical to long-term cell reliability. The work focused on understanding how titanium tab geometry, edge condition, polymer sealant thickness and surface preparation influence the ability to form a fully sealed tab-to-pouch interface.
Challenge: The key technical challenge was to create a titanium tab construction that could be sealed reliably without voids or leakage while remaining practical for future production. Titanium sheet edges can create gaps at the polymer interface if the edge profile is too square, burred or inconsistent. ARC therefore needed to determine whether edge preparation, polymer thickness and process conditions could deliver a repeatable seal, while also considering raw material availability, surface treatment options, weldability and future scale-up requirements.
Solution: ARC structured the development programme around four linked workstreams: edge preparation, polymer optimisation, surface treatment assessment and raw material supply. This allowed the project to separate the root causes of seal failure and define a practical development route before committing to higher-volume manufacture.
- Edge Preparation: ARC assessed the importance of preparing the titanium edge before sealing. The development target was to reduce the effective edge height sufficiently to avoid void formation at the polymer interface. A 16° edge-pressing approach reduced the edge height but highlighted the need for further tooling refinement and press capability before robust piece-type production could be achieved.
- Polymer Optimisation: ARC compared 150 µm and 200 µm polymer sealant films on non-edge-prepared and edge-prepared titanium. Sealing trials showed that non-edge-prepared titanium was prone to voids and leak failures, while edge preparation significantly improved seal formation. The 200 µm polymer option provided the strongest basis for a complete edge seal.
- Process Development: ARC investigated the effect of alignment aids and sealing parameters. Pressure changes had limited impact on edge-seal quality, while use of Mylar could prevent full edge sealing by restricting polymer flow. The preferred route was therefore to combine edge preparation with a sealing process that allows the polymer to flow into and around the prepared edge.
- Surface Treatment and Supply Route: ARC reviewed titanium surface treatment options and raw material supply routes. Piece-type treatments such as anodising or thermal oxide growth were identified as potential routes to improved corrosion protection, while reel-to-reel treatment options required further investigation. Broken-corner strip was identified as a preferred raw material condition to improve seal quality and reduce downstream edge-preparation burden.
Results: The feasibility study established the main design and process requirements for titanium lead tab development and reduced uncertainty around the next development phase.
- Edge preparation confirmed as critical: Unprepared titanium edges were associated with voids and leak failures, confirming that edge condition is a key driver of seal reliability.
- Preferred polymer direction identified: A 200 µm polymer sealant film was recommended as the most robust option for sealing prepared titanium edges without voids.
- Process limitation identified: Alignment methods that restrict polymer flow can introduce edge voids; the sealing process must therefore allow polymer movement into the prepared edge geometry.
- Scale-up pathway defined: The work identified the need for accelerated ageing in electrolyte, refinement of piece-type edge pressing, further surface treatment assessment where required, and pilot production trials using ARC’s tab-line capability.
Conclusion: ARC demonstrated that titanium lead tabs can be developed into a credible pouch cell component when edge geometry, polymer thickness and seal process design are treated as an integrated system. The study showed that edge preparation and a thicker polymer sealant are essential to achieving a reliable edge seal, while surface treatment and supply format require further validation before full production scale-up.