• Title/Summary/Keyword: SOFCs

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Characteristics of Sr0.92Y0.08TiO3-δ Anode in Humidified MethaneFuel for Intermediate Temperature Solid Oxide Fuel Cells

  • Park, Eun Kyung;Yun, Jeong Woo
    • Journal of Electrochemical Science and Technology
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    • v.7 no.1
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    • pp.33-40
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    • 2016
  • Sr0.92Y0.08TiO3-δ (SYT) was investigated as an alternative anode in humidified CH4 fuel for SOFCs at low temperatures (650 ℃-750 ℃) and compared with the conventional Ni/yttria-stabilized zirconia (Ni/YSZ) anode. The goal of the study was to directly use a hydrocarbon fuel in a SOFC without a reforming process. The cell performance of the SYT anode was relatively low compared with that of the Ni/YSZ anode because of the poor electrochemical catalytic activity of SYT. In the presence of CH4 fuel, however, the cell performance with the SYT anode decreased by 20%, in contrast to the 58% decrease in the case of the Ni/YSZ anode. The severe degradation of cell performance observed with the Ni/YSZ anode was caused by carbon deposition that resulted from methane thermal cracking. Carbon was much less detected in the SYT anode due to the catalytic oxidation. Otherwise, a significant amount of bulk carbon was detected in the Ni/YSZ anode.

Research on Performance of LSM Coating on Interconnect Materials for SOFCs

  • Zhai, Huijuan;Guan, Wanbing;Li, Zhi;Xu, Cheng;Wang, Wei Guo
    • Journal of the Korean Ceramic Society
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    • v.45 no.12
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    • pp.777-781
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    • 2008
  • Experiments were conducted using SUS430 and Crofer 22 APU steels coated by LSM using plasma spray and slurry spray methods, respectively. High-temperature conductivity and oxidation resistance were investigated. For comparison, SUS430 and Crofer 22 APU without LSM coating were also investigated and coefficient of thermal expansion (CTE) was measured. The results show that the materials without LSM coating exhibit almost the same CTE as YSZ electrolyte in a range of temperatures of $550{\sim}850^{\circ}C$. When coated with LSM, the oxidation rate of the steels decreases by $30{\sim}40%$ using slurry spray and by $10{\sim}30%$ using plasma spray whereas the steels using plasma spray have a better high-temperature conductivity than the steels using slurry spray. It is thus concluded that the LSM coating has a limited effect on increasing high-temperature conductivity while it can effectively reduce the oxidation of the steels.

A Simulation Study of the Effect of Microstructural Design on the Performance of Solid Oxide Fuel Cells With Direct Internal Reforming (내부개질형 고체산화물 연료전지의 마이크로 전극구조가 성능에 미치는 영향에 관한 해석적 연구)

  • Sohn, Sangho;Nam, In Hyun
    • Journal of Hydrogen and New Energy
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    • v.24 no.5
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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.

Electrochemical Performance of LSCF Cathode with GDC lnterlayer on ScSZ Electrolyte

  • Hwang, Hae-Jin;Moon, Ji-Woong;Lim, Yongho;Lee, Seunghun;Lee, Eun-A
    • Journal of the Korean Ceramic Society
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    • v.42 no.12 s.283
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    • pp.787-792
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    • 2005
  • A symmetrical LSCF $(La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-\delta})\;ScSZ(89ZrO_2-10Sc_2O_3-1CeO_2)/LSCF$ electrochemical cell with a GDC (Gadolinium-Doped Ceria, $90CeO_2-10Gd_2O_3$) interlayer that was inserted between the LSCF cathode and ScSZ electrolyte was fabricated, and the electrochemical performance of these cells was evaluated. The GDC interlayer was deposited on a ScSZ electrolyte using a screen-printing technique. The GDC interlayer prevented the unfavorable solid-state reactions at the LSCF/ScSZ interfaces. The LSCF cathode on the GDC interlayer had excellent electrocatalytic performance even at $650^{\circ}C$. The Area Specific Resistance (ASR) was strongly dependent on the thickness and heat-treatment temperature of the GDC interlayer. The impedance spectra showed that the cell with a $15\~27{\mu}m$ thick GDC interlayer heat-treated at $1200^{\circ}C$ had the lowest ASR.

Electrochemical stability of La0.6Sr0.4Co0.2Fe0.8O3-δ as a cathode for SOFC

  • Oh, Mi-Young;Jeong, Yong-Hoon;Oh, Se-Woong
    • Journal of the Korean institute of surface engineering
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    • v.49 no.6
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    • pp.498-506
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    • 2016
  • Electrochemical measurement using a LSCF6428 electrode was performed to estimate the oxygen potential gradient in the electrode layer and a long time stability test was performed by applied potential to learn the overpotential effect on the LSCF6428 electrode. By fitting the observed impedance spectra, it was obtained that the amount of faradic current decreased with distance from cathode/electrolyte interface. Oxygen potential gradient was estimated to occur within 1 um region from the cathode/electrolyte interface at an oxygen partial pressure of 10-1 bar. The segregation of cation rich phases in the LSCF6428 electrode suggests that kinetic decomposition took place. However, impedance response after applying the potential showed no changes in the electrode compared with before applying potential. The obtained results suggest that segregation of a secondary phase in a LSCF6428 cathode is not related to performance degradation for solid oxide fuel cells (SOFCs).

Characterization and Electrochemical Performance of Composite BSCF Cathode for Intermediate-temperature Solid Oxide Fuel Cell

  • Kim, Yu-Mi;Kim-Lohsoontorn, Pattaraporn;Bae, Joong-Myeon
    • Journal of Electrochemical Science and Technology
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    • v.2 no.1
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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).

Electrochemical Performance and Cr Tolerance in a La1-xBaxCo0.9Fe0.1O3-δ (x = 0.3, 0.4 and 0.5) Cathode for Solid Oxide Fuel Cells

  • Choe, Yeong-Ju;Hwang, Hae-Jin
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.308-314
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    • 2015
  • The electrochemical performance and Cr poisoning behavior of $La_{1-x}Ba_xCo_{0.9}Fe_{0.1}O_{3-{\delta}}$ (LBCF, x = 0.3, 0.4, 0.5) and $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LSCF) cathodes were investigated for solid oxide fuel cells (SOFCs). The polarization resistance of the LBCF/GDC/LBCF symmetrical cell was found to decrease with increasing Ba content (x value). This phenomenon might be associated with the high oxygen vacancy concentration in the LBCF sample, with x = 0.5. In addition, there was no chromium poisoning in the LBCF cathode. On the other hand, the polarization resistance of the LSCF cathode was found to significantly increase after exposure to gaseous chromium species; it appears that this result stemmed from the formation of $SrCrO_4$ phase. Therefore, it can be expected that LBCF can be a durable potential cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFC).

Effect of Metal Ni Atomic Layer Deposition Coating on Ni/YSZ, Anode of Solid Oxide Fuel Cells (SOFCs) (고체산화물 연료전지의 Anode인 Ni/YSZ에 Ni 원자층 증착 코팅의 효과)

  • Kim, Jun Ho;Mo, Su In;Park, Gwang Seon;Kim, Hyung Soon;Kim, Do Heyoung;Yun, Jeong Woo
    • Journal of the Microelectronics and Packaging Society
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    • v.29 no.1
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    • pp.61-66
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    • 2022
  • This study is to increase the surface area and maximize the effect of the catalyst by coating a nanometersized metal catalyst material on the anode layer using atomic layer deposition (ALD) technology. ALD process is known to produce uniform films with well-controlled thickness at the atomic level on substrates. We measured the performance by coating metals (Ni) on Ni/YSZ, which is the most widely known anode material for solid oxide fuel cells. ALD coatings began to show a decrease in cell performance over 3 nm coatings.

Experimental and Numerical Study on Flow Characteristics of a Common Exhaust System for Multiple SOFCs (SOFC용 복합 배기 시스템 유동 특성에 관한 실험 및 수치해석적 연구)

  • DAEWOONG JUNG;JONGHYUK YOON;HYOUNGWOON SONG
    • Journal of Hydrogen and New Energy
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    • v.34 no.6
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    • pp.657-666
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    • 2023
  • In this study, experiments and numerical analysis were conducted to investigate the exhaust gas flow in a common exhaust system of multiple solid oxide fuel cells. The system was fabricated based on KGS code and operated within a pressure range of 0.12 kPa, with flow rates ranging from 79.1 to 103.4 L/min. Numerical modeling was validated with a mean absolute error of 3.8% for pressure results. The study assessed the impact of changes in area ratio and emergency stops on pressure distribution, velocity vectors, and wall shear stress. The findings revealed no significant factors causing high differential pressure or backflow.

Electrical Properties of Vanadium-doped Lanthanium Silicates for SOFCs (SOFC 응용을 위한 Vanadium이 첨가된 란타늄 실리케이트의 전기적 특성)

  • Lee, Dong-Jin;Lee, Sung-Gap;Kim, Min-Ho;Kim, Kyeong-Min
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.5
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    • pp.295-299
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    • 2015
  • In this paper to improve the ionic conduction properties, lanthanum silicate apatite $La_{9.33}(SiO_4)_6O_2$ ceramic, which substituted by V ions at Si-site, were fabricated by the mixed-oxide method. And we investigated the structural and electrical properties of $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens with variation of dopants for the application of solid oxide fuel cells. The sintering temperature of $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens decreased from $1,600^{\circ}C$ to $1,400^{\circ}C$. As results of X-ray diffraction patterns, all $La_{9.33}(Si_{6-x}V_x)O_{26}$ specimens showed the formation of a complete solid solution in a apatite polycrystallin structure. But the specimens doped with more than 1.5mol% showed the second phase, $La_2SiO_5$ and $SiO_2$. The specimen dopants with 1.0 mol% showed the maximum ion conductivity. Ion conducting and activation energy of the $La_{9.33}(Si_5V_1)O_26$ specimens were about $7.8{\times}10^{-4}S/cm$ 1.62 eV at $600^{\circ}C$, respectively.