| Effect of particle sizes on the electrical conductivity characteristics of La0.8Sr0.2MnO3-δ (LSM) cathodes for solid oxide fuel cell (SOFC) |
Jeong Yun Park1, Ji Min Im1,2, Bohyun Ryu2, Seung-Wook Baek3, 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
2Fuel Cell Innovations Co., Ltd., 41-7, Techno 11-ro, Yuseong-Gu, Daejeon, Republic of Korea
3Interdisciplinary Materials Measurement Institute, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-Ro, Yuseong-Gu, Daejeon, 34113, Republic of Korea |
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Received: June 26, 2024; Revised: September 4, 2024 Accepted: September 20, 2024. Published online: March 19, 2025. |
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| ABSTRACT |
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In this study, the electrochemical and electrical conductivity properties of La0.8Sr0.2MnO3−δ (LSM)-based cathode materials were investigated with respect to different particle sizes and sintering temperatures. XRD analysis showed that LSM-L, synthesized by solid-state reaction, forms the same perovskite single phase as LSM-S. Furthermore, particle-size analysis and powder microstructure analysis verified that LSM-S has a smaller particle size than that of LSM-L. The impedance was measured using LSM cathodes with small- and large-particle sizes. Samples with LSM cathode only, and LSM and YSZ composited in 5:5 and 2:8 ratios, were prepared. Among the three samples, the sample composed of LSM and YSZ in a 5:5 ratio had the lowest area specific resistance (ASR), because it formed the most Triple Phase Boundary (TPB) and exhibited enhanced oxygen reduction reaction (ORR). When LSM and YSZ are composited at a 2:8 ratio, the YSZ particles surround the LSM particles. This limits the transport of electron holes through the LSM, resulting in a lower triple phase boundary (TPB) density. Consequently, the reduction in area-specific resistance (ASR) is minimal when YSZ is used at a higher ratio than LSM, because the decrease in electron hole mobility has a greater impact than the increase in TPB density. The LSM-S cathode, with small particles, which was sintered at 1200 ℃, exhibited the densest microstructure. The highest electrical conductivity value of 186.5 S/cm at 600 ℃ was observed in LSM-S due to the formation of a dense structure, which generated continuous electrical paths and improved the mobility of the charge carriers in the cathodes. In contrast, lower electrical conductivity values were observed in the large-particle LSM. The electrical conductivity was proportional to the sintering temperature. This is due to the increased connectivity between particles at high sintering temperatures, which results in the formation of continuous electrical path. Electrical conductivity was measured by applying currents of 0.1 A, 0.5 A, and 1.0 A. When a current of 0.1 A was applied, the sample exhibited the highest recorded electrical conductivity of 186.5 S/cm. The conductivity values were 163.6 S/cm at 0.5 A and 161.7 S/cm at 1.0 A. LSM-L showed the same behavior. This behavior was attributed to the increase in the path of charge carriers on the cathode surface as the applied current increased. |
| Key words:
Solid oxide fuel cell (SOFC) · Electrical conductivity · Electrical path · Triple phase boundary |
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