Although the coatings applied to the bipolar plates of fuel cells or electrolysers are very thin, they are a decisive cost factor in the production of these plates. For a bipolar plate for fuel cells with a size of around 750 cm², the cost of the coating should be in the low single-digit euro range per plate, depending on the layer and the system.

Simultaneous coating of both sides of a bipolar plate with typical dimensions of 500 mm x 150 mm requires a highly productive coating process and reliable coating technology. Several hundred individual bipolar plates are combined in one stack to form a fuel cell. It is obvious that the use of batch coating systems is not recommended for these quantities, as the productivity is far from sufficient.

To maximize productivity, coating systems should operate in a continuous throughput mode. This means that only so-called in-line systems, in which substrates are coated on both sides at high throughput and without rotation, are suitable for such mass production.

Components for electrolysers such as electrode plates, PTLs (porous transport layers) or GDLs (gas diffusion layers) often require the use of in-line coating systems due to the size of the components.

In contrast to batch systems, these are multi-chamber systems in which the substrates are transported from chamber to chamber. The chambers are separated by large transfer valves, allowing various defined process steps to run separately in terms of space and time. This design enables a clean environment with consistent vacuum and process conditions.

In-line systems i-L 4.3500 and i-L 3.5000

PVT has developed two different in-line systems for the hydrogen industry. Various coating processes can be carried out in both systems, each with 4 or 3 vacuum chambers. The in-line systems are designed for smooth 24/7 operation.

Depending on customer requirements, magnetron sputtering, arc evaporation or PE-CVD (plasma-enhanced chemical vapor deposition) can be used as the coating process.

The i-L 4.3500 can coat around 5,000,000 bipolar plates per year with the above-mentioned dimensions.

The internal transport system can accommodate substrates up to 3.5 x 1.5 m in size. Therefore, in addition to the bipolar plates for fuel cells, the significantly larger electrode plates or other components for electrolysers can also be coated.

With the i-L 3.5000, the maximum substrate size is around 1.8 m x 1 m.

These in-line systems enable a considerable reduction in production costs. Depending on the materials applied, durable, robust and economically very attractive coatings are possible.