Terbium-Doped SrCoO3as a New Cathode Material for IT–SOFC

Abstract Cathode materials consisting of Sr1–xTbxCoO3–δ (x = 0.1, 0.2, 0.3) were prepared from a stoichiometric mixture of SrCO3, Co3O4, and Tb4O7 for intermediate-temperature solid oxide fuel cells (IT–SOFCs). The crystal structure of Sr0.9Tb0.1CoO3–δ was defined in the cubic Pm–3 m space group (No. 221), and Sr0.8Tb0.2CoO3–δ and Sr0.7Tb0.3CoO3–δ had a tetragonal I4/mmm structure. The electrical conductivity values were all higher than 407 S · cm−1 for T ≥ 500°C. The area specific resistances (ASRs) and its activation energy (Ea) increased with increasing x. The oxygen vacancies and the thermal expansion coefficients (TECs) decreased with increasing x. The TECs were influenced by the concentration of oxygen vacancies and the transition of the Co3+ ions from a low-spin to a high-spin state. The cathodes exhibited porosity microstructure and good adhesion to solid electrolyte. Sr0.9Tb0.1CoO3–δ had the best cathode characteristics and the most stable performance.