Fraunhofer Institute for Electronic Nano Systems
Hydrogen is the fuel of the future. It is clean, sustainable and easy to store and transport, making it an alternative to fossil fuels that has the potential to advance the energy transition, secure a stable supply of energy and make a substantial contribution to protecting the climate. As an established research and development partner, Fraunhofer ENAS is supporting this path to the future by developing and manufacturing state-of-the-art hydrogen technologies.
Hydrogen is the key to more resource-efficient, cleaner energy. It is produced by splitting water into its constituent elements, hydrogen and oxygen. This process, also called electrolysis, can be done using renewable energy such as electricity from wind turbines. The resulting hydrogen is referred to as green or eco-friendly hydrogen because it does not produce harmful CO2 emissions.
Making hydrogen available for use as an energy source in Germany, Europe and worldwide requires effective electrolyzers, as well as efficient fuel cells to carry out the process of converting the hydrogen back into electrical energy and heat. Through its research and development of innovative key components for electrolyzers, fuel cells and hydrogen sensor concepts, Fraunhofer ENAS is helping to prepare the ground for a successful transition to green energy.
Printed Functionalities: Innovative catalyst inks by Fraunhofer ENAS lead to greater efficiency when creating hydrogen systems
The core components of electrolyzers and fuel cells are conversion components arranged into cell stacks. These include a catalyst-coated membrane (CCM), which is combined with other components such as sub-gaskets, a gas diffusion layer and a porous transport layer to form a membrane electrode assembly (MEA). There are two bipolar plates on the ends of each cell.
If an electrolyzer membrane is later coated with functional catalyst and precious metal layers of platinum (cathode) and iridium dioxide (anode), this enables a controlled electrochemical reaction through which water can be split into its constituent elements, hydrogen and oxygen, by means of an electric current.
To revolutionize the production of CCMs and MEAs, researchers at Fraunhofer ENAS are using a unique formula to develop innovative catalyst inks that contain platinum and iridium. “These catalyst inks are unique because they can be inkjet-printed right onto the membrane without coming into contact with it, in a single process step, so the coating is applied in no time. Established coating processes, such as slot-die and doctor blade coating, are very time- and resource-intensive because they laboriously transfer the printed anode and cathode technologies onto the membrane via an intermediate substrate called a decal film. Our process is significantly faster,” Prof. Ralf Zichner, head of the “Printed Functionalities” Department at Fraunhofer ENAS, explains.
When developing the inks, the researchers particularly focused on printability: Despite containing precious metal nanoparticles of platinum or iridium dioxide, the ink has a low viscosity, similar to the consistency of water. This makes it an ideal candidate for the inkjet printing process. The ink is applied to the membrane drop by drop, which helps to make the print extremely precise and means that the reactive functional layer can be applied accurately and evenly to the membrane. “This means not only that every drop of ink is used efficiently, but also that there is no need to go through the process of recycling unused pieces of coating. We can also vary the catalyst load, the load on the electrochemically active precious metal-based nanoparticle surface, flexibly and on an individual basis,” says the researcher.
The combination of the inkjet printing process and the functional inks developed in Chemnitz produces cost advantages for manufacturers of CCMs and MEAs: The efficient use of the costly catalyst materials platinum and iridium dioxide means that resources can be economized and the issue of environmental protection can be monitored as early as the manufacturing stage.
“This allows CCMs and MEAs to be produced in large quantities, which could reduce manufacturing costs by up to 30 percent,” says Prof. Ralf Zichner, summarizing the advantages.
