Application of Hipims Coatings to Enhance the Durability and Performance of Structural Components of PEM Electrolyzer Anodes

Abstract

Porous transport layers (PTL) and bipolar plates (BPP) are structural elements that transport water, gases, electrons as well as heat within the electrolysis cells. On the anode side, the state-of-the-art material for BPP and PTL is titanium due its higher corrosion resistance under the operating conditions of electrolysis (high electrochemical potential, acidic and oxidizing environment) compared to other materials [1]. However, titanium components tend to form an oxide layer that rises the interfacial contact resistance (ICR) and leads to a poor performance since metal oxides are semiconductors or insulators. This issue is usually addressed by applying precious metal coatings, such as platinum or gold. In this work, we present the potential of high power sputtering techniques (HiPIMS) to manufacture ultra-low loading Pt coatings (<20 nm) with good homogeneity and high performance at an industrial scale. The influence of HiPIMS parameters on coating-substrate interface, as well as the coating properties have been evaluated. SEM, AFM and HRTEM microscopy have been used to evaluate the coating thickness and morphology. XRD analysis has been carried out to evaluate the influence of the HiPIMS parameters on the growth mode of Pt coatings, tailoring the coating texture from [200] to [111]. HiPIMS technique also provide enhanced density compared with other coating techniques due to the higher ionization achieved in the plasma [2]. The deposition of denser and defect-free coatings by HiPIMS enables the application of stainless steel components. HiPIMS prevents the formation of columnar structures and reduces oxygen diffusion. In this work, Nb- and Ti-based protective coatings have been deposited by HiPIMS on stainless steel 316L. A comparative between coated Ti Gr2 and SS316L has been set, showing the potential to reduce costs in the next generation of PEMWE structural components.