Proton exchange membrane fuel cells (PEMFCs) generate electricity utilizing the energy of electrochemical reactions of fuel (H2) and oxidants (O2/air). As they emit no toxic gases during the process, they are considered as a clean energy source that can be beneficial and might replace the use of fossil fuels. To compose a FC stack, an essential component, bipolar plates (BPs), is needed. They have several roles to fulfill during PEMFC stack operation, and there are many challenges when it comes to BPs metal‐based materials and their sustainability, durability, and longevity. Finding suitable metal and alloy materials is a significant task as BP materials should have multiple qualities that sometimes come at the expense of one another. As BPs constitute a significant part of PEMFC stack by means of volume, weight, and costs, the pursuit of the most suitable and least expensive metal‐based materials is comprehensible. In this Review, different metal and alloy types (copper, nickel, titanium, and aluminum alloys) and their own particular challenges are discussed, emphasizing the most important family of materials candidates—stainless steels.

Metal nitrides (and particularly TiN) are among the most extensively investigated proton exchange membrane fuel cell bipolar plates (BP) coatings. The most employed methods of nitrides coating deposition are various modifications of physical vapor deposition (PVD), while different types of stainless steels are the most common BP materials coated with TiN PVD films. In the current work, we report on the integrity maintenance of TiN PVD coating of AISI416, considering this as a clue to the sustainability of such a film. The advantage of this combination lies in the fact that the coefficients of thermal expansion (CTE) of this alloy is close to the CTE of the TiN film. Thus, the thermal stresses of such coating are expected to be minimal, as well as related coating cracks. We conducted a thorough surface analysis of roughness evolution in the course of BP corrosion process, investigating different initial surface pretreatments. Finally, we found that fine mirror-like polished BP substrate prior to deposition is essential for TiN film's integrity during corrosion analysis time.

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