• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.847-855
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• 2000

80$0^{\circ}C$에서 작동하는 중온형 SOFC(Solid Oxide Fuel Cell) 단전지의 제조공정을 확립하고 그 출력특성을 평가하였다. 중온형 SOFC에서 문제가 되는 전해질 성분에 의한 출력 감소를 최소화하기 위해 음극기판 위에 7-15$\mu\textrm{m}$ 두께의 얇은 YSZ막을 입히는 음극지지형 SOFC를 구성하였다. 산화, 환원 반응이 일어나는 전극에서는 전극반응에 필요한 유효면적을 최대화하여 분극 저항을 줄일 수 있도록 음극으로는 Ni-YSZ 복합체를, 양극으로는 LSM-YSZ 복합체를 사용하였다. 출력특성 평가를 위한 단전지 홀더는 Inconnel을 가공하여 사용하였으며 80$0^{\circ}C$에서 최적의 밀봉효과를 나타낼 유리밀봉재를 개발하여 사용하였다. 제조한 단전지의 단면적은 5$\times$5$\textrm{cm}^2$, 10$\times$10$\textrm{cm}^2$ 두 종류였으며 운전 시험결과 5$\times$5 단전지의 경우는 최고 0.2W/$\textrm{cm}^2$, 10$\times$10 단전지의 경우는 0.12W/$\textrm{cm}^2$ 정도의 출력밀도를 나타내었다. 단전지의 출력 및 장기 안정성은 전극구조의 변화 및 단전지 홀더의 산화에 따른 접촉 저항 변화에 크게 영향을 받는 것으로 나타났으며 운전중의 연료공급 및 작동온도 변화 등에 의한 영향도 큰 것으로 나타났다.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.368-373
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• 2004

To improve the conventional cathode-supported tubular solid oxide fuel cell (SOFC) from the viewpoint of low cell power density, expensive fabrication process and high operation temperature, the anode-supported tubular solid oxide fuel cell was investigated. The anode tube of Ni-8mol% $Y_2$O$_3$-stabilized $ZrO_2$ (8YSZ) was manufactured by extrusion process, and, the electrolyte of 8YSZ and the multi-layered cathode of $LaSrMnO_3$(LSM)ILSM-YSZ composite/$LaSrCoFeO_3$ were coated on the surface of the anode tube by slurry dip coating process, subsequently. Their cell performances were examined under gases of humidified hydrogen with 3% water and air. In the thermal cycle condition of heating and cooling rates with $3.33^{\circ}C$/min, the anode-supported tubular cell showed an excellent resistance as compared with the electrolyte-supported planar cell. The optimum hydrogen flow rate was evaluated and the air preheating increased the cell performance due to the increased gas temperature inside the cell. In long-term stability test, the single cell indicated a stable performance of 300 mA/$\textrm{cm}^2$ at 0.85 V for 255 hr.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.273-279
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• 1998

Unite cell of soid oxide fuel cell (SOFC) that consists of a dense yttria-stabilized zirconia(YSZ) electrolyte a porous nickel-YSZ cermet anode and a porous strontium- doped lanthanum manganate(LSM) cathod was fabricated from using pore former through co-firing technique. Initial sintering shrinkage rates of each layer were identified for fabricating SOFC. Heterogenous sintering was very effective in tailoring shrinkage rate for three layers. The powder tailoring necessary for shrinkage rate matching are as follows ; electrolyte of 60% TZ8YS/ 40% TZ8Y mixture anode of 51wt% NiO/49 wt% (70wt% TZ8YS/30 wt% UT ZrO2) mixture and cathode of 80% LSM/20% UT ZrO2 mixture . The overall sintering shrinkage rate differences of three layers using these compositions were maintained in a few percent.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.379-381
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• 2009

The simulation model for metal-supported Solid Oxide Fuel Cell(SOFC) is developed in this study. Open circuit voltage is calculated using Nernst equation and Gibbs free energy is required by thermodynamic. The exchange current densities are compared with experimental results since exchange current density is most effective factor for the activation loss. Liu's study is used for the exchange current density of cathode, BSCF, and Koide's result is applied for the exchange current density of anode, Ni/YSZ. For the ohmic loss, ionic conductivity of YSZ is described from Kilner's mode and the data are compared with Wanzenberg's experimental data. Diffusivity is an important factor for the mass transfer through the porous medium. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.129-132
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• 2007

Advanced structure of metal-supported solid oxide fuel cells was devised to overcome sealing problem and mechanical instability in ceramic-supported solid oxide fuel cells. STS430 whose dimensions were 26mm diameter, 1mm thickness and 0.4mm channel width was used as metal support. Thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support by using a cermet adhesive. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_{3}$ perovskite oxide was used as cathode material. It was noted that oxygen reduction reaction of cathode governed the overall cell performance from oxygen partial pressure dependance.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.8-11
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• 2006

High temperature superconducting coated conductor has various buffer structures on Ni-W alloy. We comparatively studied the growth conditions of a multi buffer layer $(CeO_2/YSZ/CeO_2)$ and a single buffer layer$(CeO_2)$ on textured Ni-W alloy tapes. XRD data showed that the qualities of in-plane and out-of-plane textures of the two type buffer structures were good. Also, we investigated the properties of SmBCO superconducting layer that was deposited on the two type buffer structure. The SmBCO superconducting properties on the single and multi buffer structure showed different critical current values and surface morphologies. FWHM of In-plane and out-of-plane textures were $7.4^{\circ},\;5.0^{\circ}$ in the top CeO2 layer of the multi-buffer layers of $CeO_2/YSZ/CeO_2$, and $7.3^{\circ},\;5.1^{\circ}$ in the $CeO_2$ single buffer layer. $1{\mu}m-thick$ SmBCO superconducting layers were deposited on two type buffer layer. $I_c$ of SmBCO deposited on single and multi buffer were 90 A/cm, 150 A/cm and corresponding $J_c$ were $0.9MA/cm^2,\;1.5MA/cm^2$ at 77K in self-field, respectively.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.499-502
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• 2001

Functionally gradient NiCrAlY/$ZrO_2$-$Y_2$$O_3$ and NiCrAlY/$ZrO_2$- $CeO_2$-$Y_2$$O_3$ coatings were prepared by APS. The as-sprayed microstructure consisted of metal-rich and ceramic-rich regions, between which $Al_2$$O_3$-rich layers existed owing to the oxidation during APS. During oxidation between 900 and $1100^{\circ}C$ in air, the pre-existing $Al_2$$O_3$-rich scales grew, due mainly to the preferential reaction of Al with inwardly transporting oxygen along the heterogeneous phase boundaries. As the amount of ceramics in the coating increased, the oxidation resistance increased.

• 한국전기화학회:학술대회논문집
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• 2001.06a
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• pp.124-129
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• 2001

SOFC(Solid Oxide Fuel Cell)의 음극으로 쓰이고 있는 Ni-YSZ 복합체의 미세구조를 Ni의 함량에 따라 정량적으로 분석하고 이로부터 미세구조적인 특성과 전극특성간의 상관관계를 규명하였다. 미세구조적인 특성의 정량화를 위해 quantitative microscopy 이론을 응용해 화상분석 하였고 그로부터 복합체내 각 상들의 크기 및 분포, 각 상간의 연결도 및 계면 면적 등의 정보를 얻어내었다. 미세구조 분석결과 복합체 전극의 특성은 입자성장 등에 의한 미세구조 변화, 특히 Ni 상의 입자성장 정도에 크게 의존하였으며 이렇게 정량화된 미세구조적 인자들은 복합체가 나타내는 복잡한 전기적 물성들을 예측하는데 아주 유용하게 활용되었다.

• Progress in Superconductivity
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• v.2 no.1
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• pp.33-38
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• 2000

Ni tapes were textured by taking advantage of their secondary recrystallization. The obtained 18cm long tapes had textures of single crystalline qualities with their [001] axes tilted with respect to the surface and their [010] axes parallel to the rolling direction. The reproducibility of this texturing was checked by taking statistics on the crystal orientations of 24 Ni tapes. $YBCO/CeO_2/YSZ/CeO_2$ films grown on the Ni tape had the same crystalline orientations. Magnetic field dependent I-V relations were measured on a 5cm section of the tape. $J_c$ defined by $20{\mu}V/mm$ criterion was $1.5\times10^5A/cm^2$ at 77K under zero field and was reduced by $\sim$50% under the applied magnetic field of 5T.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.72-72
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• 2002