• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.133-136
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• 2007

Perovskite-structured samarium strontium cobaltite (SSC), which is mixed ionic electronic conductor (MIEC), is considered as a promising cathode material for intermediate temperature-operating solid oxide fuel cell (SOFC) due to its high electrocatalytic property. Cathode material containing cobalt (Co) is unstable at high temperature and has a relatively high thermal expansion property. In this paper, Sm-Sr-(Co,Fe,Ni)-O system with perovskite and spinel structures was investigated in terms of electrochemical property and thermal expansion property, respectively. Area specific resistance (ASR) was measured by ac impedance spectroscopy to investigate the electrochemical property of cathode, and thermal expansion coefficient (TEC) was measured by using dilatometer. Micro structure of cathode was observed by scanning electron microscopy. Perovskite-structured $Sm_{0.5}Sr_{0.5}CoO_{3-\delta}$ showed the ASR of $0.87{\Omega}/cm^{2}$, and $Sm_{0.5}Sr_{0.5}NiO_{3-\delta}$, which actually has a spinel structure, showed the lowest TEC value of $13.3{\times}10^{-6}/K$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.368-371
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• 2006

[ $La_{0.8}Sr_{0.2}Co_{1-x}Mn_xO_3$ ] cathode as a high performance cathode on YSZ electrolyte was studied by analyzing impedance spectra. It was shown that cathode property of $La_{0.8}Sr_{0.2}Co_{1-x}Mn_xO_3$ is bet ter than that of$La_{0.8}Sr_{0.2}CoO_3$. At $700^{\circ}C$ in air environment, $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_3$ cathode on CGO- layered YSZ electrolyte showed very low area specific resistance of $0.14{\Omega}cm^2$, which is low enough for intermediate-temperature sol id oxide fuel cells. This is because material properties of ionic conductivity and thermal expansion compatibility with electrolyte were optimized. Judging from activation energy and oxygen part i al pressure dependance of cathode property, it was noted that oxygen surface exchange kinetics is dominantly influential on cathode property in higher temperature region than $700^{\circ}C$ and oxygen self-diffusion in cathode material is more influential in lower temperature region.

• 대한기계학회논문집B
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• 제29권6호
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• pp.722-729
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• 2005

Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range thus to reduce thermal stress inside the cell. Three different methods considered are (1) adopting a burner in front of the cell, (2) adopting a preheater (heat transfer from the main combustor) in front of the cell and (3) using recirculation of the cathode exit gas. For each configuration, analyses are carried out for two values of allowable maximum cell temperature difference. Performance characteristics of all cases are compared and design limitations are discussed. Relaxation of the cell temperature difference (larger difference) is proved to ensure higher efficiency. Recirculation of the cathode exit gas exhibits better performance than other methods and this advantage becomes more prominent as the constraint of the cell temperature difference becomes more severe (smaller temperature difference).

• 대한기계학회논문집B
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• 제27권5호
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• pp.635-643
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• 2003

Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

• 대한기계학회논문집B
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• 제31권5호
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• pp.473-481
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• 2007

Compared to other types of fuel cells, SOFC has advantages like a wide output range and the direct use of hydrocarbon fuel without the process of external reforming. Particularly because the direct use of fuel without reforming reaction is closely linked to overall system efficiency, it is a very attractive advantage. We tried the operation with methane. However, although methane has a small number of carbons compared to other hydrocarbon fuels, our experiment found the deposition of carbon on the surface of the SOFC electrode. To overcome the problem, we tried the operation through activating internal reforming. The reason that internal reforming was possible was that SOFC runs at high temperature compared to other fuel cells and its electrode is made of Ni, which functions as a catalyst favorable for steam reforming.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.480-486
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• 2013

In this study, tubular SOFC unit cell with advanced anode current collector was fabricated to improve the cell performance. First, we prepared two types of single cells having the same manufacture processes such as the same electrolyte, electrode coating condition and sintering processes. And then to compare the developed single cell performance with conventional cells, we changed the anode current collecting methods. From the impedance analysis and I-V curve analysis, the cell performance of advanced cell is much higher than that of conventional cell.

• 한국수소및신에너지학회논문집
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• 제24권5호
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• pp.401-412
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• 2013

The paper is to study on the simulation of the micro/macroscale thermo-electrochemical model of a single cell of anode-supported SOFC with direct internal reforming. The coupled heat and mass transport, electrochemical and reforming reactions, and fluid flow were simultaneously simulated based on mass, energy, charge conservation. The micro/macroscale model first calculates the detailed electrochemical and direct internal reforming processes in porous electrodes based on the comprehensive microscale model and then solve the macroscale processes such as heat and mass transport, and fluid flow in SOFCs with assumption of fully-developed flow in gas channel. The simulation results evaluate the overall performance by analyzing distributions of mole fraction, current density, temperature and microstructural design in co/counter flow configurations.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.657-662
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• 2017

This paper presents the reversible electrolysis characteristics of a solid oxide fuel cell (SOFC) using a $10{\times}10cm^2$ anode supported planar cell with an active area of $81cm^2$. In this work, current-voltage characteristic test and reversible electrolysis cycle test were carried out sequentially for 2,114 hours at a furnace temperature of $700^{\circ}C$. The current-voltage characteristics for reversible electrolysis mode was measured at a current of ${\pm}26.7A$ under various $H_2O$ utilization conditions. The reversible electrolysis cycle was performed 50 times at a current of ${\pm}32.4A$. As a result, The performance degradation of SOEC mode was larger than that of SOFC mode.

• 대한기계학회논문집B
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• 제27권7호
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• pp.963-972
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• 2003

Performance characteristics of the planar-type solid oxide fuel cell (SOFC) are investigated by the analysis of flow fields coupled with heat and mass transfer phenomena in anode and cathode channels. For these purposes, performance analysis of the SOFC is conducted based on electrochemical reaction phenomena in electrodes and electrolyte coupled with flow fields in anode and cathode channels. In the present study, the isothermal model adopted in the previous paper prepared by the same authors is extended to the non-isothermal model by solving energy equation additionally with momentum and mass transfer equations using CFD technique. It is found that the difference between isothermal and non-isothermal models come from non-uniform temperature distribution along anode and cathode electrodes by solving energy equation in non-isothermal model. Non-uniform temperature distribution in non-isothermal model contributes to the increase of average temperature of the fuel cell and influences its performance characteristics.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.187-190
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• 2009

$LaCrO_3$ series are the most common candidate materials for a ceramic interconnect for SOFC and the thermal expansion coefficient of these matches very well with that of YSZ electrolyte. In this study, characteristics of the coated films on the anode-support, which were formed by using $La_{0.8}Ca_{0.2}CrO_3$, $La_{0.8}Sr_{0.2}CrO_3$, $La_{0.8}Ca_{0.2}Co_{0.1}Cr_{0.9}O_3$ for ceramic interconnet for SOFC, were investigated. All powders showed single perovskite phase and the precursors had spherical shapes of $2{\mu}m{\sim}30{\mu}m$. According to SEM analysis, coated film of LCC on pretreated anode-support was more thicker, whereas the coated film on untreated anode-support was densely formed. As the results of electrical conductivity of anode-support coated with the ceramic interconnects, LCCC exhibited the most excellent electrical conductivity of 0.15S/cm at $750^{\circ}C$.