Degradation and Corrosion of Metal Components in High-Temperature Fuel Cells and Electrolyzers: Review of Protective Approaches

High-temperature fuel cells and electrolyzers, particularly molten carbonate fuel cells (MCFCs) and Molten Carbonate Electrolyzers (MCEs), are expected to play a critical role in clean power generation, hydrogen production, and integrated CO2 separation. Unfortunately, despite their potential, these technologies have not yet reached full commercialization. The main reason for this is material degradation. In particular, the corrosion of metallic components continues to be a leading cause of performance loss and system failure. This review provides a comprehensive assessment of degradation mechanisms in MCFC and MCE systems. It examines key metallic components, such as current collectors and bipolar plates, focusing on the performance of commonly used materials, including stainless steels and advanced alloys, under prolonged exposure to corrosive environments. To address degradation issues, this review evaluates current mitigation strategies and discusses material selection, protective coatings application, and the optimization of operational parameters. Advances in alloy development, coatings, surface treatments, and process controls have been compared in terms of effectiveness, scalability, and long-term stability. The review concludes with a synthesis of current best practices and future directions, emphasizing the need for integrated, multi-functional solutions to achieve the lifetimes required for full commercialization. By linking materials science, electrochemistry, and systems engineering, this review offers directions for the development of corrosion-resistant MCFC and MCE technologies in support of a hydrogen-based, carbon-neutral energy future.