Recycling processes

Both fuel cells and electrolyzers use valuable and/or critical materials. Due to the proportion of these valuable technology metals, efficient recycling is necessary. However, no tailored recycling process is available for the majority of systems.

Researchers at the Leistungszentrum-Wasserstoff Hessen are addressing precisely this issue - keeping critical materials in the cycle, for example in the BMBF-funded BreCycle project. The research objective of the project is to develop a sustainable process for the reprocessing of fuel cells, with which high-quality material fractions can be generated, especially from the electrode coating, and the polymer membrane can be separated. Valuable precious metals such as platinum and ruthenium are of particular importance for the recycling market of fuel cells. These metals are also the focus of currently used general recycling processes for precious metals, in which polymer electrolyte membrane fuel cells are currently processed for the most part.

Platinum and ruthenium, as well as other valuable and rare metals, are recovered in pyrometallurgical metal recycling processes. However, pyrometallurgical recycling of fuel cells produces highly toxic fluorine compounds from the fluorinated Nafion membrane, which means that large-scale implementation requires very complex off-gas cleaning. To date, there are no industrially efficient recycling processes that adequately separate the polymer membranes prior to melt processing and thus eliminate the risk of hydrogen fluoride formation in the melting process. In addition, base metals such as steel or aluminium are largely lost in the process.

Here to the project

Nd-Fe-B alloys are used in high-performance permanent magnets and are of outstanding importance for electromobility and energy generation via wind power. Nd-Fe-B magnets contain rare earths, raw materials of strategic importance, which should be recycled or recyclable. 

In order to remain as energy-efficient as possible and high in the value chain, Fraunhofer IWKS is further developing methods of mechanical recycling in which the material is retained in its composition.

Hydrogen treatment is essential for these recycling routes. With the help of hydrogen embrittlement, old magnets are converted into a powder form and used as a reprocessed recyclate for the production of new magnets.