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Nomination for the Otto von Guericke award 2021: current distribution in electrolytic cells made of special paper

Papiertechnische Stiftung in Heidenau (PTS), the Fraunhofer Institute for Manufacturing Technology and Advance Materials (IFAM), and the Fuel Cell Centre – Zentrum für Brennstoffzellen-Technik GmbH in Duisburg (ZBT) made it to the finals for the Otto von Guericke Award 2021 with their joint project “Development of porous titanium current distributors for PEM electrolysis using papermaking technology“. The presentation of the research topic and the awarding of the prize are planned to take place in Berlin in December 2021.

Thanks to their outstanding interdisciplinary approach, the project leaders from the three research centres succeeded in bringing together three different technical fields to create the basis for a novel membrane-electrode assembly directed to fuel cell and electrolytic technology. One goal of this project, which is funded by the industrial collective research scheme IGF, is to reduce the cost of rolling out the water electrolysis process on an industrial scale. Such cost reduction can only be achieved by using less expensive manufacturing methods and increasing process efficiency or long-term stability.

Fig. 1: REM cross-section of a titanium-filled special paper

The focus of the project was on so-called PEM electrolytic cells. The cost breakdown of a PEM electrolytic cell shows that electric-current distributors are the dominating cost factor. To reduce the investment cost of PEM electrolytic cells, the project teams successfully worked on the idea to develop titanium-based metallic sinterable papers for use as current distributors in PEM electrolysis.

The disadvantages of conventional current distributors lie in very high manufacturing costs (fabric), high anisotropy and too low surface (nonwovens), high material thickness in connection with high manufacturing costs (sinter body), and generally excessive tolerances in parts. Highly filled special papers should allow the aforesaid problems to be solved. For this purpose, the filler content of a paper is drastically increased to such a level that the property profile of the paper will be characterised by the functionality represented by the filler instead of the fibre (refer to Fig. 1).

Fig. 2: Sintered-titanium current distributor

The fine metallic powders incorporated in the cellulose matrix are pretreated thermally be pyrolysis or oxidation. Sintering will then produce thin, porous, purely metallic bodies (refer to Fig. 2).

The project resulted in the production of various paper-derived current distributors of titanium. The titanium current distributors were then checked for their performance during the electrolysis. As a result, the research project showed that a microstructure with optimal porosity and pore size is crucial for the mode of operation of the electrolyser. Eventually, the project teams developed a current distributor comparable to the reference. The Otto von Guericke prize is awarded by AiF for the IGF project of the year. The award includes EUR 10,000 in prize money and is given by AiF since 1997 for scientists with outstanding achievements in industrial collective research (IGF).

Dr. Cornell Wüstner,