Countering diffusion and embrittlement in the storage and transport of hydrogen
Green hydrogen will play a decisive role in a successful energy transition. The development of new hydrogen technologies requires techniques and processes that enable the safe production, storage, distribution and use of hydrogen. Central material science challenges are the diffusion of hydrogen and the associated embrittlement of used material. The "Plasma Technology and Surfaces" department at Fraunhofer IFAM is researching how surfaces can be protected against this diffusion and embrittlement by treatment with plasmas or lasers. The focus is on internal coatings for tanks and pipes, but possible applications for electrolysers, bipolar plates, and fuel cells are also being investigated.
Diffusion of hydrogen and embrittlement of tanks and lines
Hydrogen is the smallest molecule and poses the challenge of safe preservation for technology from generation to consumer use (e.g. in e-cars). Walls and seams of containers or pipes must be of such quality that the molecules cannot pass through.
If the material is inadequate, the molecules can penetrate the material, causing it to become brittle. This process then favors hydrogen escaping from a container or pipe in gaseous form or as LOHC (Liquid Organic Hydrogen Carrier), even if initially only in small quantities. In the first place, this means a safety risk, but also an economic loss.
Surface technology can use plasma and laser processes to treat surfaces in such a way that such diffusion or even leakage of hydrogen is prevented.
Using plasma technology to deposit hydrogen barriers for LOHC technology, tanks and lines
A first way to prevent diffusion and leakage of hydrogen, is to treat the surfaces of tanks and lines using plasma technology. Interaction with plasmas creates layers that can act as barriers. Fraunhofer IFAM uses its extensive expertise in plasmas and plasma technologies to develop such barrier layers.
Since plasma processes can be applied to different materials such as plastics, fiber composites, or metals, applications are possible in the following areas:
- Lightweight tanks in mobile applications
- Tanks for LOHC technology
- Piping systems for the hydrogen generating and processing industry
Using laser technology to structure surfaces in electrolyzers and fuel cells
While plasma technology can be used to create barrier layers on surfaces, laser technology can be used to provide the surface with small channels. The aim is to structure surfaces with a laser treatment in such a way that, for example, gas molecules are directed along the surface in a desired direction. This surface treatment measure can additionally be combined with diffusion-preventing plasma coatings.
Therefore, such laser treatments appear to be particularly promising for the development of gas transport and gas distribution systems that are to be suitable for the transport of hydrogen. For example, one can think of electrolysers or fuel cells. In such applications, laser-structured surfaces help to guide the molecules through the system as efficiently as possible.
Plasma coating and laser structuring of bipolar plates in fuel cells
Especially in the creation of fuel cells, plasma and laser technology can be used to achieve different system goals. This is because, in addition to diffusion prevention, plasma coatings and laser structuring can be used to provide surfaces with additional functions. To name a few examples:
- Electrical conductivity
- Corrosion protection for bipolar plates
- Adhesion mediation for bonding bipolar plates
- Targeted wetting control for the drainage of reaction water
The potential applications for hydrogen technology are many and research is only beginning to fully exploit them.
Dr. Ralph Wilken is head of the department "Plasma Technology and Surfaces" at Fraunhofer IFAM. With his team of researchers, he offers extensive knowledge of all aspects of the use of plasma, laser, and VUV technologies in surface engineering. For some years now, the team has applied its expertise in the field of hydrogen technology. With its distinctive expertise in surface technology, electromobility, and hydrogen technology, Fraunhofer IFAM is a strong partner for the hydrogen economy.