Electrochemical characteristic of non-stoichiometric SmBa0.45Sr0.5Co2O5+d layered perovskite oxide system for IT-SOFC cathode

• Published in: International journal of hydrogen energy Vol. 48; no. 46; pp. 17664 - 17676
• Main Authors: Song, Kyeong Eun, Schlegl, Harald, Kang, Hyunil, Choi, Wonseok, Kim, Jung Hyun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29.05.2023
• Subjects: Area specific resistance; Electrical conductivity; Microstructure; Non-stoichiometric composition cathode; Solid oxide fuel cell; Electrical conductivity; Non-stoichiometric composition cathode; Microstructure; Solid oxide fuel cell; Area specific resistance
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2023.01.255

In this study, the composition of the layered perovskite SmBa0.5Sr0.5Co2O5+d was changed to different non-stoichiometric compositions by changing the substitution amount of Ba and Sr. SmBa0.45Sr0.5Co2O5+d (SBSCO-0.45/0.5) showed the lowest area specific resistance (ASR) because the area % caused by high binding energy (HBE) of O1s in the X-ray photoelectron spectroscopy (XPS) analysis was the largest compared to all other tested compositions and also the unit cell volume was smaller than that of other samples. The dense SmBa0.5Sr0.48Co2O5+d (SBSCO-0.5/0.48) showed the highest electrical conductivity. This is because SBSCO-0.5/0.48 has the smallest decrease in oxygen contents compared to other samples when subject to temperature increase. Also, through XPS analysis, it was found that the area % of the Co3+ and Co4+ coexistence regions of Co2p of SBSCO-0.5/0.48 was the largest. The electrical conductivity values and behaviors of the porous SBSCO-0.45/0.5 and SBSCO-0.5/0.48 were not significantly different. Comparing the single-cell performance with composite cathodes comprised of SBSCO-0.45/0.5 and SBSCO-0.5/0.48 with CGO91, the results show that the single-cell with the SBSCO-0.45/0.5 and CGO91 cathode showed higher maximum power density. •Layered perovskites with non-stoichiometric compositions in A/-site were selected.•The area specific resistance of SmBa0.45Sr0.5Co2O5+d was the lowest.•The electrical conductivity of dense SmBa0.5Sr0.48Co2O5+d was the highest.•Metallic electrical conductivity changes to semiconductor as the microstructure changes.•Porous SmBa0.5Sr0.48Co2O5+d and SmBa0.45Sr0.5Co2O5+d have similar conductivity values.