| Electrical conductivity and electrochemical characteristics of layered perovskite cathodes with Co and Fe substitution |
Yu Taek Hong1, Jeong Yun Park1, Yu Ri Lim1, Jin Woo Cha1, Chae Eun Kim1, Jun Woong Kim2, Abul K. Azad3, Seung-Wook Baek4, Jung Hyun Kim1
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1Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yuseong-Gu, Daejeon 34158, Republic of Korea
2EXSEN Inc., 49, Techno 3-Ro, Yuseong-Gu, Daejeon 34015, Republic of Korea
3Faculty of Integrated Technologies, Universiti Brunei Darussalam, Gadong BE1410, Brunei
4Division of Chemical and Material Metrology-Emerging Material Metrology Group , Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-Ro, Yuseong-Gu, Daejeon 34113, Republic of Korea |
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Received: May 23, 2025; Revised: July 20, 2025 Accepted: September 12, 2025. Published online: September 23, 2025. |
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| ABSTRACT |
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In this study, SmBaCo2xFe2(1-x)O5+δ (SBCF) cathodes with varying compositions (x = 0.1, 0.3, 0.5, 0.7, and 0.9) were synthesized via a conventional solid-state reaction method and systematically investigated for application in Intermediate Temperature-operating solid oxide fuel cells (IT-SOFCs). Phase purity and structural evolution were confirmed by X-ray diffraction (XRD), and electrochemical properties including electrical conductivity and area-specific resistance (ASR) were evaluated to assess the effect of composition. Scanning electron microscopy (SEM) was employed to analyze the microstructure and its correlation with electrochemical performance. All compositions with a Co substitution ratio of x ≥ 0.7 met the minimum electrical conductivity requirement of 100 S/cm. Notably, the SBCF 1.8-0.2_1200 (x = 0.9) exhibited the highest electrical conductivity of 764.99 S/cm at 300 °C in air. Surface microstructural analysis confirmed grain growth with increased heat-treatment temperature, with SBCF 1.8-0.2_1200 exhibiting the largest average grain size of around 4.68 μm. Moreover, a composite cathode formed by mixing SBCF 1.8-0.2_1100 with CGO91 in a 1:1 ratio exhibited the lowest area-specific resistance (ASR) of 0.06 Ω·cm2 at 700 °C, which was attributed to the enhanced ion transport, reduced thermal expansion mismatch, and an extended triple-phase boundary (TPB). These results demonstrate that SBCF 1.8-0.2 is a promising cathode composition for IT-SOFC applications and provide valuable insight into compositional design strategies for high-performance SOFC cathodes. |
| Key words:
Intermediate temperature-operating SOFC (IT-SOFC) · Layered perovskite structure · Electrical conductivity · Area-specific resistance (ASR) · Composite cathode |
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