Influence of operating conditions on the fuel electrode degradation of solid oxide electrolysis cell investigated by phase field model with wettability analysis

Ni coarsening and migration in the Ni-based fuel electrode are the major degradation mechanisms that lead to performance deterioration and reduced durability of solid oxide electrolysis cell (SOEC). In this study, the relationship between working conditions, including gas composition and overpotential, and electrode attenuation is investigated by employing functional graded electrode as the research object. The Phase Field Model (PFM) is proposed to capture microscopic variations in SOEC electrode under different wettability characteristics. After degradation to various degrees, a Lattice Boltzmann method (LBM) is developed to simulate the mesoscale transport of the potential distribution of electrons and ions. The effects of Ni coarsening and depletion in the functionally graded electrode are separately discussed. The multi-phase morphology, distribution of overpotential, and reaction rates are obtained and analyzed from mesoscale simulation. Finally, an evaluation criterion based on Ni degradation mechanism is established to objectively assess the performance of Ni-based electrodes.