Challenges and Perspectives of Metal-Based Proton Exchange Membrane's Bipolar Plates: Exploring Durability and Longevity

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.