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

Abstract

Symmetrical solid oxide fuel cells (SSOFCs), in which the same material serves as anode and cathode simultaneously, 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+δ (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) × 10−6 K-1, 14.72(6) × 10−6 K-1 in 5% H2/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-δ (LSGM) electrolyte and thus leads to a lower polarization resistance. The LSGM electrolyte (300 μm) supported symmetrical cell with SBMM electrodes delivers a maximum power density of 596 mW cm-2 at 900 °C. These results demonstrate that SmBaMn1.9Mg0.1O5+δ is a highly promising electrode material for SSOFCs.