Comprehension and Mitigation of Metal Corrosion Modes in Reversible Solid Oxide Cells

Reversible Solid Oxide Fuel Cell (R-SOFC) systems operating at elevated temperatures are being developed for efficient power generation and H2 production. Commonly available materials and fabrication processes have been utilized for the fabrication of cells and stacks. Long term operation of R-SOFC stacks, however, shows the surface oxidation and corrosion of the metallic cell and stack components due to high temperature operation in high steam and H2 conditions, leading to performance degradation. Metal degradation in H2-H2O atmospheres representative of R-SOFC systems remain largely undocumented in literature and need to be understood to avoid premature failure. PCI has developed R-SOFC with high specific power and will utilize our experience to experimentally confirm failure modes in the metallic cell structure and components. We will then implement recent advances in powder metallurgy, processing, and manufacturing to mitigate the corrosion mechanisms’-SOFC’s are subject to surface, interface, and bulk chemical and structural changes in the metallic components exposed to anodic, cathodic, and bi-polar exposure conditions. These include localized scaling and formation of porous non-protective multi-constituent oxide scales at the metal surface. Accelerated metal corrosion has been attributed to modifications in the oxidation processes due to a variety of pathways, leading to changes in ionic and electronic structure and percolation in the oxide scale. A key objective will be to develop an understanding and address accelerated metallic cell and stack component corrosion and degradation processes in H2-H2O atmospheres and at high temperatures utilizing co-stability, thermochemistry, mechanical and oxide defect structure modifications. In Phase I, we will examine the role of H2 permeation in thin metallic components at 600-900?C and implement modification strategies to improve the metal corrosion resistance. We propose to (i)experimentally validate metal corrosion models at R-SOFC operating conditions, (ii) develop novel metal substrate with new alloy compositions to mitigate degradation, and (iii) develop alloy metallurgy, surface coatings, and/or pre-treatment for cell/stack components. Approaches for surface and bulk alloy protection will be developed, evaluated, and cost effectiveness analyzed. The samples will be evaluated understock/SOEC mode (up to 90% steam in H2) to confirm chemical, mechanical and electrical stability. During Phase II, we will optimize alloy chemistry and manufacturing, including fabrication of larger cells and sub stack evaluation under reversible-SOFC conditions .R-SOFC is known for very efficient hydrogen usage (power generation) and production, and the proposal focuses on improving the durability of R-SOFC cells and metal components. Our proposed approach realizes cost effective R-SOFC system with highly efficient operation for both SOFC and SOEC mode. The technology is superior compared to the low temperature PEM fuel cells but is at a lower TRL. The proposed work will improve the durability and performance of R-SOFC’s for power and H2 generation. It will improve overall economics and scalability and potentially provide low-cost hydrogen for industrial decarbonization and clean and sustainable power generation.