Abstract
Chromium poisoning in the solid oxide fuel/electrolysis cell deteriorates cell performance by blocking active sites and forming poorly conducting secondary phases. Previous studies have indicated the mechanisms of chromium deposition vary between SOFC and SOEC modes. This study investigates the effects of electrochemical states (SOFC mode vs. SOEC mode) on chromium poisoning using symmetric cells consisting of LSC air electrodes. The cells were tested in the presence of Crofer mesh, both non-coated and Ni-Co coated. A voltage bias was applied to the symmetric cell to induce one electrode to be oxidized (i.e., to be SOEC air electrode) and another one to be reduced (i.e., to be SOFC air electrode). A reference electrode was added to the symmetric cell to measure the overvoltage of each electrode. By applying constant current, we assessed how chromium deposition affects cell degradation relative to the current density. Electrochemical analyses, including electrochemical impedance spectroscopy (EIS), current-voltage measurements, scanning electron microscopy (SEM), electrical dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to understand the chromium migration and deposition pathways and their influences on air electrode in SOEC vs. SOFC modes. The results demonstrate diverse chromium poisoning mechanisms in each mode, influenced by electrochemical states and operational conditions.
Published Version
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