Electrochemical performance and structural durability of Mg-doped SmBaMn2O5+δ layered perovskite electrode for symmetrical solid oxide fuel cell

Symmetrical solid oxide fuel cells (SSOFCs), in which the same material serves as anode and cathode simulta-neously, have attracted substantial attention because of the simplified electrode/electrolyte interface issue and cell fabrication process. The exploration of suitable electrode material for SSOFC is a great challenge. In this work, Mg-doped SmBaMn1.9Mg0.1O5+delta (SBMM) with Sm-Ba layered ordering is proposed as SSOFC electrode material. The SBMM shows high structure reversibility upon thermal and redox cycling, with orthorhombic Pmmm symmetry in air and tetragonal P4/nmm structure in reducing atmosphere. It exhibits similar thermal expansion coefficients of 15.14(1) x 10(-6) K-1, 14.72(6) x 10(-6) K-1 in 5% H-2/Ar and air, respectively. Mg-doping decreases the chemical-induced expansion of SBMM remarkably, which ensures good thermomechanical compatibility of SBMM with La0.8Sr0.2Ga0.8Mg0.2O3-6 (LSGM) electrolyte and thus leads to a lower polarization resistance. The LSGM electrolyte (300 mu m) supported symmetrical cell with SBMM electrodes delivers a maximum power density of 596 mW cm(-2) at 900 degrees C. These results demonstrate that SmBaMn1.9Mg0.1O5+delta is a highly promising electrode material for SSOFCs.