Stainless steel based anode porous transport layers for PEM water electrolysis

The energy system and the chemical industry of the present and future require large quantities of hydrogen. A key technology for the production of green hydrogen is the polymer electrolyte membrane water electrolysis (PEMWE). However, investment costs are high due to the use of iridium, platinum and titanium. One way to reduce costs is to partially replace titanium used for the porous transport layers (PTL) by stainless steel. Therefore, we used 316L expanded metals and coated them with titanium by cold gas spraying (CGS) for corrosion protection. Thereby, the average layer thickness was reduced from 60±12µm to 48±16µm to 33±16µm. The corrosion stability of the expanded metals was evaluated by long-term measurements for up to 1006h at 2.0V, impedance spectroscopy, analyzing water samples and performing post mortem analysis of cross-sections of the membrane electrode assemblies (MEAs). With 48µm and 33µm thick coatings, cationic contamination caused by corrosion lead to increasing ohmic resistances and catalyst inactivation. In contrast, with thicker protective coatings of 60µm, PEMWE operation was conducted for 1006h at 2.8Acm-2 without any evidence of corrosion impact and with performance close to state-of-the-art PTLs. With this newly developed PTL, around 58% Ti-savings can be achieved compared to full titanium PTLs.