Various concepts and materials are used for the reliable sealing of fuel cell and electrolyzer stacks. These include prefabricated flat seals or O-rings, which are predominantly manufactured using cost- and time-intensive injection molding or molding processes. Coating expert Laufenberg GmbH and WEVO-CHEMIE GmbH, which specializes in polyurethanes, epoxies, and silicones, are now presenting a process for the continuous and high-speed roll-to-roll production of flat elastomer seals. This opens up a scalable way for manufacturers of fuel cells and electrolyzers to reduce costs, while also supporting efficient automated production processes.

The process at a glance

After mixing, the 2-component elastomers developed by Wevo are applied in liquid form to a carrier film using a coating system from Laufenberg. Coating is carried out in a roll-to-roll process and can be applied to one or both sides. Curing takes place in a continuous oven with several zones, the temperature of which can be adjusted individually for each material. Optional pre-curing using infrared radiators shortens the curing time and removes any air bubbles that may be present. Throughput speeds of 0.5 to 50 meters per minute allow for flexible scaling. The customer receives the non-sticky, cured material either as a roll or as custom-cut seals. The process allows layer thicknesses of around 20 micrometers to two millimeters for a pure elastomer seal. In combination with carrier films, hybrid seals with a total thickness of 70 micrometers to four millimeters can be produced, depending on the core carrier. This allows both very thin and highly resilient seals to be manufactured.

Selection of carrier film and elastomer

The selection of the elastomer and the carrier film depends on the type of electrolyzer, fuel cell, or redox flow battery. Here, manufacturers of fuel cell and electrolyzer stacks benefit from the many years of expertise of both companies. Laufenberg contributes its expertise in the coating of silicone materials. If a pure elastomer seal is required, a carrier film is selected that can be removed after the Wevo material has cured. Alternatively, the carrier film remains in place, creating a hybrid seal. This can be useful, for example, with very soft sealants in order to increase dimensional stability and pressure resistance.

Customized solutions also available on request

For many years, Wevo has been developing special silicones and modified polyurethanes with low hydrogen permeation, which are already being used successfully as liquid sealants and adhesives in fuel cell and electrolyzer stacks. Until now, these have been applied as a bead of sealant to bipolar plates or flux frames using screen printing or dispensing processes. The process developed in collaboration with Laufenberg enables the production of prefabricated seals in a roll-to-roll process. Among other things, the pot life and curing time of the materials are specially adapted – individually on request.

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