Thermal spay coatings for cost-effective and durable bipolar plates of Polymer membrane water electrolyser

Transition towards intermittent renewable energy demands strategies for reliable and secure energy supply. Power-to-gas is tapped for large scale grid stabilization and hydrogen production via electrolysis is a key enabling technology. Electrolytic hydrogen market in Europe is already seeing unprecedented growth with four fold increase in 10 years. Among different electrolysers, Proton Exchange Membrane Water Electrolyser (PEM-WE) is considered to become the dominating technology for electrolytic hydrogen production by 2030.

Cost reduction and high efficiency are the major challenges for sustainable H₂
production using PEM-WE. Titanium-based components, namely bipolar plates (BPP), have the largest contribution to the capital cost. This work proposes the use of stainless steel BPPs coated with Ti/Nb by vacuum plasma spraying (VPS) and physical vapor deposition (PVD). The physical properties of the coatings are characterized by scanning electron, atomic force microscopies (SEM, AFM); and X-ray diffraction, photoelectron spectroscopies (XRD, XPS). A 50 μm Ti coating protects the stainless steel substrate against corrosion, while a 50- fold thinner layer of Nb decreases the contact resistance by almost one order of magnitude. The Nb/ Ti-coated stainless steel bipolar BPPs endure the harsh environment of the anode for more than 1000 h of operation under nominal conditions, showing a potential use in PEM electrolyzers for large-scale H₂ production from renewables.