• Title/Summary/Keyword: SOFC anode

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Characteristics of SOFC Anode of Ni/YSZ Core-shell Manufactured Using sSpherical Ni and Nano YSZ Powders (구형 Ni과 나노 YSZ Powder를 이용하여 제조한 Ni/YSZ Core-shell의 SOFC 연료극 특성)

  • Choi, Byung-Hyun;Koo, Ja-Bin;Seol, Kwang-Hee;Ji, Mi-Jung
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.1
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    • pp.40-46
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    • 2017
  • We reviewed the electrical properties of SOFC anode manufactured using spherical Ni and nano YSZ powder. When core-shell is fabricated by using submicron Ni as core and nano-sized YSZ as shell for SOFC anode, the electrical conductivity of the $0.2{\mu}m$ Ni-YSZ core-shell was 3 times higher than that of $1.0{\mu}m$ NiO or $1.0{\mu}m$ Ni-YSZ. Hydrogen selectivity was similar at $800^{\circ}C$, but hydrogen selectivity and methane conversion rate under $750^{\circ}C$ was 10~25% higher, Power density was more than 2 times, ASR was about 1/3, when exposed to $H_2$ atmosphere at $750^{\circ}C$ for a long time, Ni particles did not have any growth or cut off conduction path.

Preparation of Electrolyte Thin Film for Anode Support Type Solid Oxide Fuel Cells by Electrophoretic Deposition and Dip-Coating (전착법과 담금법에 의한 음극지지형 SOFC 지르코니아 전해질막 제조)

  • 김상우;이병호;손용배;송휴섭
    • Journal of the Korean Ceramic Society
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    • v.36 no.8
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    • pp.791-798
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    • 1999
  • The preparation method of yttria-stabilized zirconia(YSZ) thin film for an anode support type solid oxide fuel cell(SOFC) by electrophoretic deposition(EPD) and dip-coating was studied. And the difference in both preparation method was investigated through basic understanding of processing parameters which may significantly affect weight microstruxcture and defect of film. In dip-coating the thickness of film increased with time until 30 s and then the weight of film decreased with time due to particle falling off from the coagulated film. In EPD although the weight of film increased with time and applied constant-current sagging of the film was observed when the applied current was less that 0.035 mA/$cm^2$ and more than 120 s. Since YSZ thin film by EPD on porous substrate was dense smooth and homogeneous it was expected to be suitable for the electrolyte of an anode support type SOFC.

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Modeling for the Performance Analysis of a Tubular SOFC/MGT Hybrid Power System (원통형 고체산화물 연료전지와 마이크로 가스터빈 하이브리드 시스템의 성능해석을 위한 모델링)

  • Song, T.W.;Sohn, J.L.;Kim, J.H.;Kim, T.S.;Ro, S.T.;Suzuki, K.
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.2070-2075
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    • 2004
  • Performance of a solid oxide fuel cell (SOFC) can be enhanced by converting thermal energy of its high temperature exhaust gas to mechanical power using a micro gas turbine (MGT). A MGT plays also an important role to pressurize and warm up inlet gas streams of the SOFC. In this study, the influence of performance characteristics of the tubular SOFC on the hybrid power system is discussed. For this purpose, detailed heat and mass transfer with reforming and electrochemical reactions in the SOFC are mathematically modeled, and their results are reflected to the performance analysis. The analysis target is 220kWe SOFC/MGT hybrid system based on the tubular SOFC developed by Siemens-Westinghouse. Special attention is paid to the ohmic losses in the tubular SOFC counting not only current flow in radial direction, but also current flow in circumferential direction through the anode and cathode.

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Characteristics of Anode-supported Flat Tubular Solid Oxide Fuel Cell (연료극 지지체식 평관형 고체산화물 연료전지 특성 연구)

  • Kim Jong-Hee;Song Rak-Hyun
    • Journal of the Korean Electrochemical Society
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    • v.7 no.2
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    • pp.94-99
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    • 2004
  • Anode-supported flat tubular solid oxide fuel cell (SOFC) was investigated to increase the cell power density. The anode-supported flat tube was fabricated by extrusion process. The porosity and pore size of Ni/YSZ ($8mol\%$ yttria-stabilized zirconia) cermet anode were $50.6\%\;and\;0.23{\mu}m$, respectively. The Ni particles in the anode were distributed uniformly and connected well to each other particles in the cermet anode. YSZ electrolyte layer and multilayered cathode composed of $LSM(La_{0.85}Sr_{0.15})_{0.9}MnO_3)/YSZ$ composite, LSM, and $LSCF(La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.7}O_3)$ were coated onto the anode substrate by slurry dip coating, subsequently. The anode-supported flat tubular cell showed a performance of $300mW/cm^2 (0.6V,\; 500 mA/cm^2)\;at\;500^{\circ}C$. The electrochemical characteristics of the flat tubular cell were examined by ac impedance method and the humidified fuel enhanced the cell performance. Areal specific resistance of the LSM-coated SUS430 by slurry dipping process as metallic interconnect was $148m{\Omega}cm^2\;at\;750^{\circ}C$ and then decreased to $148m{\Omega}cm^2$ after 450hr. On the other hand, the LSM-coated Fecralloy by slurry dipping process showed a high area specific resistance.

Fabrication of Co-Planar Type Single Chamber SOFC with Patterned Electrodes (패턴된 전극을 가진 표면 전도형 단실형 고체산화물 연료전지의 제조)

  • Ahn, Sung-Jin;Kim, Yong-Bum;Moon, Joo-Ho;Lee, Jong-Ho;Kim, Joo-Sun
    • Journal of the Korean Ceramic Society
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    • v.43 no.12 s.295
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    • pp.798-804
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    • 2006
  • Co-planar type single chamber solid oxide fuel cell with patterned electrode on a surface of electrolyte has been fabricated by robo-dispensing method and microfluidic lithography. The cells were composed of NiO-GDC-Pd or NiO-SDC cermet anode, $(La_{0.7}Sr_{0.3})_{0.95}MnO_3$ cathode, and yttria stablized zirconia electrolyte. The cell performance at $900^{\circ}C$ was investigated as a function of electrode geometries, such as anode-to-cathode distance, numbers of electrode pairs. Relationship between OCV and I-V characteristics at the optimized operation condition was also studied by DC source meter under the mixed gas condition of methane, air, and nitrogen. An increase of anode-facing-cathode area leads to lower OCV due to intermixing between product gases of anode and cathode, which in turn decreases the oxygen partial pressure difference.

Effect of Oxidation of Ni on the Microstructure of Ni/YSZ Anode and Crack Formation in YSZ Electrolyte Layer for SOFC (Ni의 산화가 고체산화물 연료전지용 Ni/YSZ 연료극의 미세조직과 전해질의 균열에 미치는 영향)

  • Lim, Jun-Sil;Choi, Jong-Joon;Kwon, Oh-Jong
    • Journal of the Korean Ceramic Society
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    • v.43 no.12 s.295
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    • pp.805-811
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    • 2006
  • The microstructural changes in Ni/YSZ anode substrate and crack formation during Ni oxidation were investigated. The composition of as-sintered anodes was 56 wt% NiO+44 wt% YSZ and that of electrolyte was 8 mol% yttria. After complete reduction, specimens were oxidized in $N_2$ + air at $600\sim800^{\circ}C$. Oxygen partial pressure was controlled in between 0.05 atm and 0.2 atm $O_2$. When the anode was oxidized, at higher than $690^{\circ}C$, three layers were formed in the specimens. The first was fully oxidized layer(NiO/YSZ), the second was a mixed layer and the third, near-intact layer. Under $640^{\circ}C$ such distinctive layers were not observed. Cracks formed at electrolyte layer when weight gain attained at $65\sim75%$ of the total gain due to complete oxidation despite of different oxidation temperature and oxygen partial pressure.

Prediction of Mechanical and Electrical Properties of NiO-YSZ Anode Support for SOFC from Quantitative Analysis of Its Microstructure (미세조직 정량 분석을 통한 고체산화물연료전지용 NiO-YSZ 연료극 지지체의 기계적/전기적 성능 예측)

  • WAHYUDI, WANDI;KHAN, MUHAMMAD SHIRJEEL;SONG, RAK-HYUN;LEE, JONG-WON;LIM, TAK-HYOUNG;PARK, SEOK-JOO;LEE, SEUNG-BOK
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.5
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    • pp.521-530
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    • 2017
  • Improving the microstructure of NiO/YSZ is one of several approaches used to enhance the electrical and mechanical properties of an anode support in Solid Oxide Fuel Cells (SOFCs). The aim of the work reported in this paper was to predict the relationship between these microstructural changes and the resulting properties. To this end, modification of the anode microstructure was carried out using different sizes of Poly (Methyl Methacrylate) (PMMA) beads as a pore former. The electrical conductivity and mechanical strength of these samples were measured using four-probe DC, and three-point bend-test methods, respectively. Thermal etching followed by high resolution SEM imaging was performed for sintered samples to distinguish between the three phases (NiO, YSZ, and pores). Recently developed image analysis techniques were modified and used to calculate the porosity and the contiguity of different phases of the anode support. Image analysis results were verified by comparison with the porosity values determined from mercury porosimetry measurements. Contiguity of the three phases was then compared with data from electrical and mechanical measurements. A linear relationship was obtained between the contiguity data determined from image analysis, and the electrical and mechanical properties found experimentally. Based upon these relationships we can predict the electrical and mechanical properties of SOFC support from the SEM images.

Characterization of Ni/YSZ Anode Coating for Solid Oxide Fuel Cells by Atmospheric Plasma Spray Method (고체산화물 연료전지를 위한 플라즈마 용사코팅 Ni/YSZ 음극 복합체의 특성평가)

  • Park, Soo-Dong;Yoon, Sang-Hoon;Kang, Ki-Cheol;Lee, Chang-Hee
    • Journal of Welding and Joining
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    • v.26 no.4
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    • pp.50-54
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    • 2008
  • In this research, anode for SOFC has been manufactured from two different kinds of feedstock materials through thermal spraying process and the properties of the coatings were characterized and compared. One kind of feedstock was manufactured from spray drying method which includes nano-components of NiO, YSZ (300 nm) and graphite. And the other is manufactured by blending the micron size NiO coated graphite, YSZ and graphite powders as feedstock materials. Microstructure, mechanical properties and electrical conductivity of the coatings as-sprayed, after oxidation and after hydrogen reduction containing nano composite which is prepared from spray-dried powders were evaluated and compared with the same properties of the coatings prepared from blended powder feedstock. The coatings prepared from the spray dried powders has better properties as they provide larger triple phase boundaries for hydrogen oxidation reaction and is expected to have lower polarization loss for SOFC anode applications than that of the coatings prepared from blended feedstock. A maximum electrical conductivity of 651 S/cm at $800^{\circ}C$ was achieved for the coatings from spray dried powders which much more than that of the average value.

Synthesis and Properties of Y0.08Sr0.92Fe0.3Ti0.7O3 as Ceramic Anode for SOFC (SOFC의 세라믹 음극물질로서 Y0.08Sr0.92Fe0.3Ti0.7O3의 합성 및 물성 평가)

  • Lee, Tae-Hee;Jeon, Sang-Yun;Im, Ha-Ni;Song, Sung-Ju
    • KEPCO Journal on Electric Power and Energy
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    • v.7 no.1
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    • pp.161-165
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    • 2021
  • In general, SOFCs mainly use Ni-YSZ cermet, a mixture of Ni and YSZ, as an anode material, which is stable in a high-temperature reducing atmosphere. However, when SOFCs have operated at a high temperature for a long time, the structural change of Ni occurs and it results in the problem of reducing durability and efficiency. Accordingly, a development of a new anode material that can replace existing nickel and exhibits similar performance is in progress. In this study, SrTiO3, which is a perovskite-based mixed conductor and one of the candidate materials, was used. In order to increase the electrical conduction properties, Y0.08Sr0.92Fe0.3Ti0.7O3, doped with 0.08 mol of Y3+ in Sr-site and 0.03 mol of transition metal Fe3+ in Ti-site, was synthesized and its chemical diffusion coefficient and reaction constant were measured. Its electrical conductivity changes were also observed while changing the oxygen partial pressure at a constant temperature. The performance as a candidate electrode material was verified by predicting the defect area through the electrical conductivity pattern according to the oxygen partial pressure.

Power Generating Characteristics of Anode-Supported SOFC fabricated by Uni-Axial Pressing and Screen Printing (일축가압/스크린인쇄 공정에 의해 제조된 음극지지형 SOFC의 출력특성)

  • 정화영;노태욱;김주선;이해원;고행진;이기춘;이종호
    • Journal of the Korean Ceramic Society
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    • v.41 no.6
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    • pp.456-463
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    • 2004
  • To enhance the performance of anode-supported SOFC, single cell fabrication procedure was changed for better and resulting power generating characteristics of single cell were investigated. Liquid condensation process was employed for the granulation of NiO/YSZ powder mixture and the produced powder granules were compacted into anode green substrate by uni-axial pressing. YSZ electrolyte was printed on green substrate via screen-printing method and co-fired at 1400$^{\circ}C$ for 3 h. LSM/YSZ composite cathode of which the composition and heat treatment condition was adjusted to minimize the polarization#resistance with AC-impedance spectroscopy, was screen printed. The final single cell size from this multi-step procedure was 5${\times}$5 $\textrm{cm}^2$ and 10${\times}$10 $\textrm{cm}^2$. The maximum power densities of 5${\times}$5 and 10${\times}$10 single cells were about 0.45 W/$\textrm{cm}^2$ and 0.22 W/$\textrm{cm}^2$ at 800$^{\circ}C$, which are two times superior than those from single cells fabricated by the conventional process in previous our work.