Crystal structure, thermal expansion and long-term behaviors of SmBaCoO 5+δ as cathode for intermediate-temperature solid oxide fuel cells

Abstract

SmBaCo 2 O 5+δ (SBC) was studied as cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The crystal structure, thermal expansion behavior, and electrochemical performance with long-term operation of SBC were characterized. An orthorhombic layered perovskite structure was observed in SBC cathode by a GSAS program for refinement. The average thermal expansion coefficient (TEC) is 21.6 x 10 -6 K -1 in the temperature range of 100 o C-800 o C. For long-term testing, the polarization resistance of SBC cathode increases gradually from 25.77 Ω cm 2 for 2 h to 38.77 Ω cm 2 for 96 h at 600 ° C, and an increasing-rate for polarization resistance is around 13,8% h -1 . Based on the electrochemical properties, SBC cathode with mixed ionic and electronic conductor (MIEC) behavior is a potential cathode for intermediate temperature solid oxide fuel cells based on a SDC electrolyte.