Synthesis and evaluation of thermal, electrical, and electrochemical properties of Ba 0.5Sr 0.5Co 0.04Zn 0.16Fe 0.8O 3-δ as a novel cathode material for IT-SOFC applications

Abstract

Ba 0.5Sr 0.5[Co xZn 0.2-x]Fe 0.8O 3-δ, (x = 0, 0.04, 0.08, 0.12) cathode formulations were successfully synthesized by solid state reactions and the effect of cobalt doping at Zn site of Ba 0.5Sr 0.5Zn 0.2Fe 0.8O 3-δ (BSZF0. 2) on the electrical conductivity, the polarization resistance and electrochemical behavior was evaluated. X-ray diffraction patterns indicate that a single cubic perovskite phase of Ba 0.5Sr 0.4Co 0.8Fe 0.2O 3-δ oxide is successfully obtained. Ba 0.5Sr 0.5Co 0.04Zn 0.16Fe 0.8O 3-δ (BSCZF0. 16) exhibited a high electrical conductivity of 10 S/cm at 400 °C in comparison to the BSZF0. 2 showing 5.5 S/cm. Further, BSCZF0. 16 also possess a low polarization resistance as low as 0.22, 0.38, 0.87, and 1.55 Ω cm 2 at 750, 700, 650, and 600 °C in air, respectively. Accordingly, a low activation energy value of 149.8 kJ/mol for BSCZF0. 16 in comparison to 159.4 kJ/mol for BSZF0. 2 indicates high catalytic efficiency. Enhancement of desirable properties such as electrical conductivity in combination with low-polarization resistance and low-activation energy values can be attributed to the coexistence of Co and Zn in the B-site of BSCZF0. 16 leading to the multivalent states which contributes to the enhanced electron transport properties demonstrating BSCZF0. 16 as a better cathode for intermediate temperature solid oxide fuel cells applications. © 2012 Springer-Verlag.