Advancements and challenges in corrosion-resistant coatings for metallic bipolar plates: enhancing durability and sustainability in proton exchange membrane fuel cells

Proton exchange membrane fuel cells (PEMFCs) are pivotal for sustainable energy, yet metallic bipolar plates (BPs) are suffered from corrosive degradation in acidic environments, with ions being released that poison catalysts and reduce cell efficiency. In this review, advances in corrosion-resistant coatings and structural designs to enhance BP durability are comprehensively analyzed. Graphite, composite, and metal BPs are evaluated, with stainless steel and titanium being established as leading materials due to their mechanical robustness and conductivity. Further, coatings (inert metals, carbon-based, nitrides, oxides, conductive polymers) are categorized, with metal nitrides being highlighted as optimal for balancing corrosion resistance and electrical performance. Innovatively, multilayer architectures are used to suppress ion penetration, with corrosion current densities being reduced. The study is concluded with future directions emphasizing scalable multilayer coatings for PEMFC commercialization.