• 마이크로전자및패키징학회지
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• 제22권4호
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• pp.77-82
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• 2015

To increase the performance of solid oxide fuel cell operating at intermediate temperature ($600^{\circ}C{\sim}800^{\circ}C$), $Sm_{0.2}Ce_{0.8}O_2$ (SDC) thin layer was applied to the $La_{0.8}Sr_{0.2}Mn_{0.8}Cu_{0.2}O_3$ (LSMCu) cathode by sol-gel coating method. The SDC was employed as a diffusion barrier layer on the yttria-stabilized zirconia(YSZ) to prevent the interlayer by-product formation of $SrZrO_3$ or $La_2Zr_2O_7$. The by-products were hardly formed at the electrolyte-cathode interlayer resulting to reduce the cathode polarization resistance. Moreover, SDC thin film was coated on the cathode pore wall surface to extend the triple phase boundary (TPB) area.

• 대한기계학회논문집B
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• 제32권12호
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• pp.963-969
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• 2008

The performance behavior of solid oxide fuel cell using $H_2$ and CO as fuels was investigated. The power densities and impedance results showed a little variation as the ratio of $H_2$ and CO changed. However, when the pure CO was used as a fuel, area specific resistance (ASR), especially low frequency region, was increased. This might be due to carbon deposition on anode. The maximum power density was 60% lower using CO than using $H_2$. Carbon deposition reduced after constant current was applied. The SOFC performance was recovered from the carbon deposition after applying constant current during 100h.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.61-64
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• 2008

$Pr_{0.3}Sr_{0.7}Co_{0.3}Fe_{0.7}O_{3-\delta}$ (PSCF3737) was prepared and characterized as a cathode material for intermediate temperature-operating solid oxide fuel cell (IT-SOFC). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and electrical property measurement were carried out to study cathode performance of the material. XPS and EXAFS results proved that oxygen vacancy concentration was decreased and lattice constants of the perovskite structure material were increased by doping Fe up to 70 mol% at B-site of the crystal structure, which also extended the distance between oxygen and neighbor atoms. Thermal expansion coefficient (TEC) of PSCF3737 is smaller than that of $Pr_{0.3}Sr_{0.7}CoO_{3-\delta}$(PSC37) due to lower oxygen vacancy concentration. PSCF3737 showed better cathode performance than PSC37. It might be due good adhesion by a smaller difference of TEC between $Gd_{0.1}Ce_{0.9}O_2$ (CGO91) and electrode. Composite material PSCF3737-CGO91 showed better compatibility of TEC than PSCF3737. However, PSCF3737-CGO91 did not represent higher electrochemical property than PSCF3737 due to decreased reaction sites by CGO91.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2001년도 연료전지심포지움 2001논문집
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• pp.118-123
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• 2001

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.84.1-84.1
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• 2011

Typical solid oxide fuel cells (SOFCs) have limited applications because they operate at high temperature due to low ionic conductivity of electrolyte. Thin film solid oxide fuel cell with yttria stabilized zirconia (YSZ) electrolyte is developed to decrease operating temperature. Pt/YSZ/Pt thin film SOFC was fabricated on anodic aluminum oxide (AAO). The crystalline structure of YSZ electrolyte by sputter is heavily depends on the roughness of porous Pt layer, which results in pinholes. To deposit YSZ electrolyte without pinholes and electrical shortage, it is necessary to deposit smoother and denser layer between Pt anode layer and YSZ layer by sputter. Atomic Layer Deposition (ALD) technique is used to deposit pre-YSZ layer, and it improved electrolyte quality. 300nm thick Bi-layered YSZ electrolyte was successfully deposited without electrical shortage.

• Journal of Electrochemical Science and Technology
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• 제2권1호
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• pp.32-38
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• 2011

The composite barium strontium cobalt ferrite (BSCF) cathodes were investigated in the intermediate temperature range of solid oxide fuel cells (SOFCs). The characteristics and electrochemical performances of composited BSCF/samarium doped ceria (SDC); BSCF/gadolinium doped ceria (GDC); and BSCF/SDC/GDC were compared to single BSCF cathode. The BSCF used in this study were synthesized using glycine nitrate process and mechanically mixing was used to fabricate a composite cathode. Using a composite form, the thermal expansion coefficient (TEC) could be reduced and BSCF/SDC/GDC exhibited the lowest TEC value at $18.95{\times}10^{-6}K^{-1}$. The electrochemical performance from half cells and single cells exhibited nearly the same trend. All the composite cathodes gave higher electrochemical performance than the single BSCF cathode (0.22 $Wcm^{-2}$); however, when two kinds of electrolyte were used (BSCF/SDC/GDC, 0.36$Wcm^{-2}$), the electrochemical performance was lower than when the BSCF/SDC (0.45 $Wcm^{-2}$) or BSCF/GDC (0.45 $Wcm^{-2}$) was applied as cathode ($650^{\circ}C$, 97%$H_2$/3%$H_2O$ to the anode and ambient air to the cathode).

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.2969-2973
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• 2014

A new process to fabricate a composite LSCF-Ag cathode material for SOFCs by electron beam (e-beam) irradiation process has been suggested for operation under intermediate temperature range of $600-700^{\circ}C$. A composite LSCF-Ag cathode with uniformly coated Ag nanoparticles on the surface of the LSCF material was prepared by a facile e-beam irradiation method at room temperature. The morphology of the composite LSCF-Ag material was analyzed using a TEM, FE-SEM, and EDS. The prepared composite LSCF-Ag material can play a significant role in increasing the electro-catalytic activities and reducing the operating temperature of SOFCs. The performance of a tubular single cell prepared using the composite LSCF-Ag cathode, YSZ electrolyte and a Ni/YSZ anode was evaluated at reduced operating temperature of $600-700^{\circ}C$. The micro-structure and chemical composition of the single cell were investigated using a FE-SEM and EDS.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.166-166
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• 1999

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.132-139
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• 2020

Solid oxide fuel cells (SOFCs) are among one of the promising technologies for efficient and clean energy. SOFCs offer several advantages over other types of fuel cells under relatively high temperatures (600℃ to 800℃). However, the thermal behavior of SOFC stacks at high operating temperatures is a serious issue in SOFC development because it can be associated with detrimental thermal stresses on the life span of the stacks. The thermal behavior of SOFC stacks can be influenced by operating or material properties. Therefore, this work aims to investigate the effects of the thermal conductivity of each component (anode, cathode, and electrolyte) on the thermal behavior of samarium-doped ceria-based SOFCs at intermediate temperatures. Computational fluid dynamics is used to simulate SOFC operation at 600℃. The temperature distributions and gradients of a single cell at 0.7 V under different thermal conductivity values are analyzed and discussed to determine their relationship. Simulations reveal that the influence of thermal conductivity is more remarkable for the anode and electrolyte than for the cathode. Increasing the thermal conductivity of the anode by 50% results in a 23% drop in the maximum thermal gradients. The results for the electrolyte are subtle, with a ~67% reduction in thermal conductivity that only results in an 8% reduction in the maximum temperature gradient. The effect of thermal conductivity on temperature gradient is important because it can be used to predict thermal stress generation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2021-2025
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• 2007

Performance of single cell at solid oxide fuel cell (SOFC) system is largely affected by electrocatalytic and thermal properties of cathode. Samarium-based perovskite oxide material is recently recognized as promising cathode material for intermediate temperature-operating SOFC due to its high electrocatalytic property. Perovskite structured $Sm_{0.5}Sr_{0.5}CoO_{3-\delta}$ and its composite material, $Sm_{0.5}Sr_{0.5}CoO_{3-\delta}/Sm_{0.2}Ce_{0.8}O_{1.9}$ were investigated in terms of area specific resistance (ASR), thermal expansion coefficient (TEC), thermal cycling and long term performance. $Sm_{0.2}Ce_{0.8}O_{1.9}$ was used as electrolyte material. Electrochemical ac impedance spectroscopy (EIS) and dilatometer were used to measure the cathodic properties. Composite cathode ($Sm_{0.5}Sr_{0.5}CoO_{3-\delta}$: $Sm_{0.2}Ce_{0.8}O_{1.9}$ = 6:4) showed a good ASR of 0.13${\Omega}$ $cm^2$ at 650$^{\circ}C$ and its TEC value was 12.3${\times}$10-6/K at 600$^{\circ}C$ which is similar to the value of ceria-based electrolyte of 11.9${\times}$10-6/K. Performance of composite cathode was maintained with no degradation even after 13 times thermal cycle test.