Synthesis and evaluation of thermal, electrical, and electrochemical properties of Ba_(0.5)Sr_(0.5)Co_(0.04)Zn_(0.16)Fe_(0.8)O_(3-δ) as a novel cathode material for IT-SOFC applications

摘要

Ba_(0.5)Sr_(0.5)Co_(0.04)Zn_(0.16)Fe_(0.8)O_(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_(0.5)Sr_(0.5)Co_(0.04)Zn_(0.16)Fe_(0.8)O_(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_(0.5)Sr_(0.5)Co_(0.04)Zn_(0.16)Fe_(0.8)O_(3-δ) oxide is successfully obtained. Ba_(0.5)Sr_(0.5)Co_(0.04)Zn_(0.16)Fe_(0.8)O_(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 ft 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.