Dynamic Testing of Cold Gas Sprayed Bipolar Plates–Porous Transport Layer Coating System in Proton Exchange Membrane Water Electrolysis

Thermal spraying is an established technology in the coating industry offering high deposition rates and a broad range of processable materials. In addressing the scale‐up of proton exchange membrane water electrolyzers, thermal spraying presents a promising solution for cell component production, despite several challenges that need to be overcome: Firstly, the substrate material is typically characterized by a relatively thin thickness and complex geometries. Secondly, the coatings often exhibit process‐related roughness. This study demonstrates that this rough coating can be beneficial in enhancing the connection between the bipolar plate (BPP) and the porous transport layer (PTL). The developed coldgas sprayed BPP–PTL coating system was tested in an electrochemical accelerated stress test (AST) as well as in an intermittent long‐term single‐cell test. The results indicate that the BPP–PTL coating system is electrochemically stable during the AST, and subsequent measurements of electrical resistance confirm that the interface is preserved from severe oxidation. In the long‐term test, it was demonstrated that a single cell could be operated with a cell voltage of U _cell = 1.9 V at a current density of i = 2 A/cm ² over 3 months. For the first time, a fully cold gas sprayed BPP–PTL coating system has been tested in a single‐cell test for proton exchange membrane water electrolysis applications.