Wevo-Chemie has unveiled Wevosil 20000 A/B, a silicone sealant designed for alkaline environments in AEM electrolysers and flow batteries
The material offers mechanical stability, optimised electrical properties and chemical resistance. Application can be manual, semi- or fully automated, and, together with Laufenberg, it is possible to manufacture flat gaskets with different property profiles.
Alkaline electrolytes, elevated operating temperatures, and sustained compression in anion exchange membrane (AEM) electrolysers and certain flow batteries, such as organic redox flow batteries, create demanding conditions for sealants and adhesives. Wevosil 20000 A/B was developed for these environments, ensures reliable sealing of stack components, and can also be used as an adhesive if required.
Liquid application by dispensing or screen printing
For initial testing and manual applications, Wevosil 20000 A/B can be applied in liquid form with standard twin-cartridge systems because of its 1:1 mixing ratio. In series production, the material can be applied to cell components such as bipolar plates, the gas diffusion layer, the flow frame and the membrane electrode assembly (MEA). Depending on the groove configuration and component design, different sealing geometries with variable widths and heights can be achieved. Its low viscosity also enables Wevosil 20000 A/B to flow into undercuts.
Processing via dispensing or screen printing also supports an efficient, scalable production process. Additionally, curing at 100°C to 140°C in a convection oven, or with an IR (infrared) heater, can reduce cycle times, allowing the material to cure tack-free in one to two minutes.
Manufacturing prefabricated flat gaskets
Together with Laufenberg, flat gaskets made from Wevosil 20000 A/B are manufactured using a continuous roll-to-roll (R2R) process, with or without a carrier film. The coating process enables the production of very thin, flexible gaskets. The material is applied in a layer measuring 50–500µm onto an adhesive or a non-adhesive carrier film.
Adhesive carrier films can be coated on both sides with silicone sealant, allowing greater layer thicknesses. If a non-adhesive film is used, such as a fluorine-based one, the Wevosil layer can be peeled off the film after curing, creating a flat gasket without a carrier film.
Users can cut individual seals in the required design from this prefabricated sheet material and install them in the stack, simplifying test cell and short stack production. On request, Laufenberg can manufacture flat gaskets according to individual customer and component requirements.
Sealant for AEM electrolysis and organic redox flow batteries
To withstand continuous compression within the stack, Wevosil 20000 A/B has a low hardness of 50 Shore A, high elasticity, and a low compression set of 2% at room temperature and <10% at 100°C.
The good dielectric properties support electrical insulation and voltage resistance, including dielectric strength >20kV/mm and a high volume and surface resistivity of >1014Ω·cm. This enables the silicone sealant to reduce unwanted creep and shunt currents. Additionally, the formulation is free from per- and polyfluoroalkyl substances (PFAS).
