Schaeffler has developed a new generation of metallic bipolar plates featuring a novel design and an innovative coating system. Schaeffler’s new plates enable a fuel cell stack power density of 4.6 kW per liter of fuel cell volume (including end plates and compression hardware).

Fuel cell stacks made using the new Schaeffler plates can achieve a power density about 20% greater than that of stacks made using previous-generation plates.

Fuel cell stacks with new metallic bipolar plates by Schaeffler exceed the power density of stacks made with previous-generation plates by about 20%. Photo: Schaeffler (Daniel Karmann)

At a purpose-built pilot production facility in Herzogenaurach, the company is now manufacturing the new plates in runs of up to several tens of thousands of units for use by international vehicle manufacturers in prototype and small-series production.

The plates developed by Schaeffler feature a new design optimized for large-series production and leverage an innovative coating process for long fuel cell life.

When it comes to drive systems for commercial vehicles, Schaeffler is also investing in hydrogen, especially for long-haul applications. We are developing both individual components and complete subsystems for fuel cells and are gearing up for their full-scale industrialization.

—Matthias Zink, CEO Automotive Technologies at Schaeffler AG

The fully automated facility is part of Schaeffler’s center of excellence for hydrogen, a complex that also includes an extensive array of testing equipment. The facility has been designed so that it can also be used to manufacture large plates of the type used for electrolyzers. Schaeffler is thus ensuring both sustainable motion and the sustainable supply of green hydrogen.

Schaeffler is due to start production of bipolar plates under the name of Innoplate, a joint venture with Symbio, in Haguenau, France, at the start of 2024.

Schaeffler has developed an innovative design that makes optimal use of the plate’s surface area. The finer and more precise the structures on the bipolar plate, the more efficient the plate is.

—Dr Jochen Schröder, Schaeffler’s head of E-Mobility

For vehicle applications, several hundred of these plates are layered on top of one another, each separated by a membrane electrode assembly (MEA), to form a stack. The plates account for up to 80% of the stack’s weight, and up to 65% of its volume. Stacks comprising up to 400 of these cell units have a total power output of up to 140 kW—enough for light commercial vehicles. Heavy commercial vehicles up to 40 tons generally require two stacks.

Another feature of the metallic bipolar plates made by Schaeffler is the coating system used. The purpose of coatings is to maintain a high level of electrical conductivity over the fuel cell’s entire service life. Schaeffler’s solution is “Enertect”—a family of high-performance coating systems developed specifically for bipolar plates. Depending on the customer’s requirements, the coatings can be engineered for maximum plate service life, minimum carbon footprint, or an optimized price-performance ratio.

Thanks to our capabilities in surface technology, we are able to offer each customer an application-specific coating solution. This means we can meet each customer’s requirements in terms of balancing cost, performance, and manufacturing-related CO₂ emissions.

—Jochen Schröder

The coatings are applied using a specially adapted and fine-tuned version of the physical vapor deposition (PVD) process that Schaeffler has used successfully in the production of millions upon millions of highly stressed valvetrain components over the years.

To make fuel cells gas- and watertight—vital from a quality and safety perspective—Schaeffler uses either injection-molded or silk screen gaskets, or, depending on requirements, a special laser welding process developed in-house.