Flying should finally become more environmentally friendly. However, the demands placed on alternative propulsion systems in aviation are very high. They must be particularly light, powerful and, above all, reliable. The Duisburg-based ZBT is currently working with its partners to develop an optimized fuel cell stack for a hydrogen propulsion system with these properties. The aim of the project, known as KT2GP (KeyTechToGreenPower), is to achieve a power density of more than six kilowatts per kilogram.

To achieve this, the weight of the stack must be greatly reduced. To this end, the project partners are analyzing and optimizing the entire manufacturing process for bipolar plates – from forming, cutting and joining to sealing – in order to identify and exploit optimization potential. For example, the heavy stainless steel used for the bipolar plates is to be replaced by lightweight materials such as titanium.

Within the project, ZBT is focusing on the process of applying the seal using dispenser technology. To this end, a highly integrated sealing system is being developed for the bipolar plate, taking into account minimal thicknesses with optimized materials, adapted media tunneling concepts and the integration of the sealing groove on the welding contour.

In addition, ZBT is testing suitable qualification concepts with which the process quality can be monitored and the long-term stability of the components at the sealing and bipolar plate level can be ensured – always, of course, with the specific requirements of the aviation application in mind. To analyze the sealing materials, hydrogen permeation is measured on the one hand. On the other hand, the materials on the bipolar plate are evaluated using a newly developed optical quality assurance system. In addition, the coatings for the bipolar plate are examined at ZBT using corrosion current measurements (ex-situ), resistance measurements and in single-cell fuel cell operation (in-situ) with aviation-specific operating behavior.

In total, two complete stacks with the targeted power density of more than six kilowatts per kilogram are to be produced in this project. Furthermore, an assembly island for stack assembly will be set up to assemble the fuel cells fully automatically into a stack.

After the project, the fuel cell system will be validated and verified in a ground test. It should thus demonstrate its suitability for aviation applications with hydrogen as an energy source.