• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.193-198
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• 2007

KIER has been developing the anode supported flat tubular SOFC stack for the intermediate temperature $(700{\sim}800^{\circ}C)$ operation. for this purpose, we have first fabricated anode supported flat tubular cells by the optimization between the current collecting method and the induction brazing process. After that we designed the compact fuel & air manifold by adopting the simulation technique to uniformly supply fuel & air gas and the unique seal & insulation method to make the more compact stack. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90cm^2$ of connected in series with 12 modules, in which one module consists of two cells connected in parallel. The performance of stack in 3 % humidified $H_2$ and air at $800^{\circ}C$ shows maximum power of 507 W. Through these experiments, we obtained basic & advanced technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular SOFC stack in KIER.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.137.1-137.1
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• 2010

SOFC cell 하나의 전위차는 약1.1V이기 때문에 발전용으로 사용하기 위해서는 수많은 단전지를 직렬로 연결하는 구조가 필요하다. 이러한 stack의 디자인에서 발생하는 문제를 획기적으로 개선한 형태가 하나의 지지체에 셀을 직렬로 연결함으로 전극의 선폭 및 단위 셀 간의 간격이 기존 평판형, 원통형에 비해 대폭 축소되어 전극 및 연결재의 저항손실을 최소화할 수 있는 Segmented형 SOFC이다. Segmented SOFC에 적용하기 위한 세라믹 다공성 지지체는 연료와 공기에서의 화학적 안정성, 셀의 구성소재와 반응이 없으며 열팽창계수가 유사해야하는 특성을 가져야하는데 그 중에서도 지지체로써 적절한 기계적 강도와 높은 가스투과도가 요구되어진다. 본 연구에서는 고온에서 안정한 Spinel의 MgAl2O4를 주성분으로 하는 다공성 지지체를 압출 성형하여 평관형으로 제조하였으며 활성탄을 기공형성제로 사용하여 연료의 공급이 원활하도록 약 30%의 기공율을 가지는 다공성 세라믹 지지체를 제조하였다. 제조된 세라믹 지지체에 연료극(NiO/YSZ), 전해질(TZ8Y), 공기극(LSM)을 코팅하여 실제 SOFC에 적용이 가능함을 확인하였다.

• 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.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.283-287
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• 2007

KIER has been developing the anode-supported flat tubular solid oxide fuel cell unit bundle for the intermediate temperature($700{\sim}800^{\circ}C$) operation. Anode-supported flat tubular cells have Ni/YSZ cermet anode support, 8 moi.% $Y_2O_3$ stabilized $ZrO_2(YSZ)$ thin electrolyte, and cathode multi-layer composed of Sr-doped $LaSrMnO_3(LSM)$, LSM-YSZ composite, and $LaSrCoFeO_3(LSCF)$. The prepared anode-supported flat tubular cell was joined with ferritic stainless steel cap by induction brazing process. Current collection for the cathode was achieved by winding Ag wire and $La_{0.6}Sr_{0.4}CoO_3(LSCo)$ paste, while current collection for the anode was achieved by using Ni wire and felt. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90\;cm^2$ connected in series with 12 unit bundles, in which unit bundle consists of two cells connected in parallel. The performance of unit bundle in 3% humidified $H_2$ and air at $800^{\circ}C$ shows maximum power density of $0.39\;W/cm^2$ (@ 0.7V). Through these experiments, we obtained basic technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular cell unit bundle.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.93.2-93.2
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• 2012

연료전지는 전기화학반응을 이용한 발전 장치로서 기존 장치에 비하여 발전 효율이 높아 화석연료를 사용하면서 현재 당면 과제인 $CO_2$ 배출량 절감이 가능하고, 환경 보전성이 우수하여 미래의 전원으로 많은 연구개발이 진행되고 있다. 특히 제3세대 연료전지라 불리는 고체산화물 연료전지(Solid Oxide Fuel Cell이하 SOFC)는 고가의 외부 개질 장치 없이도 연료가 갖는 화학에너지를 연소과정 없이, 공기와 $H_2$, CO, $CH_4$와 같은 환원성 가스를 공급받아 $600{\sim}1000^{\circ}C$에서 전기화학적 반응을 통하여 직접 전기를 얻는 방식이며, 낮은 소음과 진동으로 인하여 온 사이트(On-site) 발전이 가능한 장점이 있는 연료전지이다. Decalcomanie는 전사용지에 Screen printing하여 건조 후 coating하는 방법으로 기존의 여러 coating 방법보다 다전지셀 제작이나 Buffer layer의 적용이 용이하고, 소재의 크기나 두께조절이 간편하며, 구성층의 표면조도나 굴곡에 대응이 용이한 방법이다. 새로운 Decalcomanie를 사용하여 평관형 다전지식 SOFC Cell 제작 및 각 Buffer layer에 적용, Screen printing법과 동일한 Cell 제조 후 MPD와 Impedance 분석을 통하여 Support 위에 전사지를 이용, 적층한 Cell의 전기화학적 특성에 관하여 분석하였다.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.246-250
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• 2011

Effects on sintering and electrical properties of $La_{0.7}Ca_{0.3}Cr_{0.9}Co_{0.1}O_{3-{\delta}}$ system, a interconnect material for cylindrical and flat tubular solid oxide fuel cells (SOFC), have been investigated by Ca-source when using $CaCO_3$ and $CaF_2$. When using $CaCO_3$ and $CaF_2$ was mixing as Ca-source, single phased perovskite solid solution was observed for each sample. The sintering temperature was decreased by $CaF_2$ contents was increased. When using 0.1 mole $CaF_2$ was densely sintered at $1400^{\circ}C$ and relative density was 93.8%. Also, electrical conductivity in oxidation and reducing atmosphere was 47, 4.3 S/cm, respectively, due to $F^-$ ion enhance the electrical conductivity in reducing atmosphere.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.357-361
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• 2014

An Ni-Fe/YSZ core-shell structured anode for uniform microstructure and catalytic activity was synthesized. Flat tubular segmented-in-series solid oxide fuel cell-stacks were prepared by decalcomania method using synthesized anode powder. The Ni-Fe/YSZ core-shell anode exhibited better electrical conductivity than a commercially available Ni-YSZ cermet anode. Also power output increased by 1.3 times with a higher open circuit voltage. These results can be attributed to the uniformly distributed Ni particles in the YSZ framework. The impedance spectra of a Ni-Fe/YSZ core-shell anode showed comparable reduced ohmic resistance similar to those of the commercially available Ni-YSZ cermet anodes.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.768-774
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• 2006

The microstructure of Ni-YSZ cermets was controlled with fine and coarse starting powders (NiO and YSZ) to obtain a optimum strong and conductive tubular anode support for SOFCs. Three types of cermets with different microstructures, i.e., coarse Ni-fine YSZ, fine Ni-coarse YSZ, and fine Ni-fine YSZ, were fabricated to investigate their electrical and mechanical properties. The cermets from fine NiO powder showed high electrical conductivity due to the enhanced percolation of Ni particles. The cermet by foe Ni and coarse YSZ showed excellent electrical conductivity (>1000 S/cm) despite its high porosity $(\sim40%)$ but it showed poor mechanical strength due to the lack of percolation by YSZ particles and due to large pores. Thus fine NiO and YSZ powders were used to make strong and conductive Ni-YSZ support tube by extrusion. The microstructure of the anode tube was modified by the amount of polymeric additives and carbon black, a pore former. Ni-YSZ tube (porosity $\sim34%$) with the finer microstructure showed better performance both in electrical conductivity (>1000 S/cm) and fracture strength $(\sim140\;MPa)$. Either flat or circular NiO-YSZ tubes with the length from 20 to 40cm were successfully fabricated with the optimized composition of materials and polymeric additives.