EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The traditional single cell preparation is usually complicated with several sintering steps to accommodate the chemical features of anode and cathode in single cell construction. Differently, symmetrical SOFCs (SSOFCs) require only one sintering step for both electrodes preparation, which minimizes the incompatibility interface problems and lowers the cell fabrication costs. Based on first principle calculation, SmBaMn2O5+δ (SBM) was selected as parent material for the use of SSOFC electrodes. SBM material exhibits relatively good electrochemical performance. Mg and Ti dopants are employed to substitute partial Mn to control the chemical expansion and so improve the thermomechanical compatibility of electrode with electrolyte. The decreased electrode polarization resistance and enhanced electrochemical performance of the constructed cells are correlated with lattice structure modification and defect formation induced by Mg and Ti replacement. Co substitution at Mn site with certain amount of A-site deficiency leads to dual phase composite electrode formation at both anode and cathode sides in cell operation environments, Co metal/SBM and Co oxide/SBM, respectively, which enables a remarkably reduced polarization resistance and enhanced cell output power density. The electrolyte-supported (300 μm) symmetrical cell with (SmBa)0.9Mn1.8Co0.2O5+δ as symmetrical electrodes delivers a maximum power density of 710 mW cm-2 at 900 °C, showing its promising as SSOFC electrode.