Investigation of the seawater impact on the state-of-the-art solid oxide electrolyzes cells performance and stack components degradation

Solid oxide cells (SOCs) are a promising technology for high-efficiency hydrogen production and can be considered as a solution in marine areas with unlimited water resources. However, seawater-derived contaminants challenge their deployment, particularly in applications involving steam generation from insufficiently purified salt water. This study investigates the impact of vapors from controlled NaCl- and multicomponent synthetic salt-water solutions on state-of-the-art anode-supported SOCs operated in electrolysis mode at 700 °C in a stack-relevant housing. Salt exposure is ensured inside the cell housing through an internal contamination source, overcoming limitations of previous studies in which salt deposition in upstream components reduced the actual exposure of the cell. Electrochemical characterization and post-mortem analysis are performed for reference cells and cells exposed to simulated seawater vapors featuring 30 g L−1 NaCl, 30 g L−1, and 7 g L−1 multicomponent synthetic salt concentration. Results show that high-salinity vapors reduce cell durability. NaCl causes mainly an increase in ohmic resistance (+32% vs. reference after 120 h), while multicomponent synthetic salt also provokes changes in ohmic and polarization resistance of contaminated cell (respectively +11% and +13% vs. reference after 120 h). Multicomponent salt mixtures exhibit the strongest degradation effects, including agglomeration and coarsening of the Ni grains, local porosity increase, and visible damage to sealing materials and steel contact meshes. Early performance decay is not observed in test with low-salinity vapors. While these findings provide initial insights, the observed microstructural changes raise a critical question for future research. Further investigation is warranted to mitigate long-term operation impact material integrity over extended life cycles.