Evaluation of SOEC segmented performance through experimental localized fuel electrode multisampling technique

In this study, a commercial solid oxide electrolysis cell (SOEC) was tested under different operating conditions to evaluate electrochemical performance and thermochemical gradients at the fuel electrode. An innovative test bench with eleven sampling points distributed across the electrode surface enabled in-operando measurements of gas composition and temperature, uncovering performance gradients not detectable by conventional inlet-outlet analysis. Experiments were carried out on a fuel-electrode-supported cell (81 cm2 active area), varying inlet flow rate and composition. A simplified electrochemical-thermal model, developed from experimental data and fundamental electrochemical and thermodynamic principles, was validated and used to predict local voltage, current density, and temperature distributions. The results indicate high electrochemical activity near the inlet, with local current densities up to 0.45 A/cm2 and thermal gradients of about 4.5 degrees C across the cell surface. Overall, the study provides new insights into the spatial heterogeneity of SOEC operating parameters and underscores the relevance of localized diagnostics. Such approaches improve the understanding of electrochemical and thermal behavior, supporting strategies to enhance SOEC efficiency and durability.