Ralf Bandorf, Stefan Körner, Ingmar Bialuch, Fraunhofer IST, Braunschweig, Germany
Proton exchange membrane (PEM) water electrolyzers currently rely on massive titanium (Ti) flow fields and bipolar plates (BPP) on the anode side to ensure sufficient corrosion resistance and low interfacial contact resistance under highly oxidizing, acidic conditions. However, the use of bulk Ti as BPP substantially increases system cost and limits large‐scale deployment. In this work, we investigate Ti‑coated stainless steel substrates as a cost‑effective alternative to monolithic Ti plates, employing high power impulse magnetron sputtering (HIPIMS) to deposit dense, adherent Ti coatings tailored for PEM electrolyzer operation.
Ti layers are deposited on industrially relevant stainless-steel grades using a HIPIMS process optimized for high ionization fraction and coating density. The coated substrates are characterized with respect to interfacial contact resistance and corrosion behavior and compared with conventional Ti plates.
The study demonstrates that HIPIMS‑deposited Ti coatings can provide a continuous, protective barrier on stainless steel, enabling corrosion resistance and electrical performance suitable for PEM electrolyzer components, while significantly reducing the use of bulk Ti. The combination of low‑cost steel substrates with advanced Ti coatings offers a promising pathway to lower material costs and improve the economic viability of PEM water electrolysis without compromising durability or performance.