SmBaCo 2O 5+d and LnBa 0.5Sr 0.5Co 2O 5+δ potential cathode materials for IT-SOFC

Abstract

The electrical conductivity of SmBaCo 2O 5+δ (SBCO) showed a Metal-Insulator Transition (MIT) at about 200°C with maximum conductivity of 570 S·cm at 200°C and minimum conductivity 170 S·cm at 900°C. The area specific resistance (ASR) of composite cathode (50wt% of SBCO and 50wt% of Ce 0.9Gd 0.1O 1.95, SBCO:50) on a Ce 0.9Gd 0.1O 1.95 (CGO91) electrolyte was observed to be 0.05 Ω·cm at 700°C. SmBaO5Sr05Co2O 5+δ (SBSCO) electrode was sintered onto CGO91 at 1000°C to form symmetrical cells and exhibited an ASR value of 0.092 Ω· cm at 700°C. The lowest ASR value was observed when the composite cathode of 50wt% of SBSCO and 50wt% of CGO91 (SBSCO:50) was used and these were 0.10 Ω·cm at 600°C and 0.013 Ω·cm at 700°C, respectively. The coefficient of thermal expansion (CTE) was 21.9 x 10 K at 700°C. However, the CTE of SBSCO:50 was shown to be 13.6 x 10 K at 700°C which are similar to the value of CGO91 electrolyte for intermediate temperature-operating solid oxide fuel cell (IT-SOFC) applications. ©The Electrochemical Society.