• 한국세라믹학회지
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• 제35권10호
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• pp.1070-1077
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• 1998

Effect of current collecting layer on the cathode was characterized by AC impedance spectroscopy at 800$^{\circ}C$ under flowing air. LSM-YSZ composite cathode showed lower polarization resistance due to the in-crease of triple phase (LSM/YSZ/Pore) boundary length by incorporation of YSZ. Ohmic resistance {{{{ {R }_{1 } }} of LSM-YSZ was higher than that of pure LSM however because in-plane resistance of the cathode was fair-ly high due to its high specific resistivity. To reduce the in-plane resistance of LSM-YSZ cathode cathode side current collecting layer was required. Ohmic resistance {{{{ {R }_{1 } }} was reduced after forming LSM current col-lecting layer on the LSM-YSZ cathode. In case of pure LSM cathode the formation of Pt, or LSCO current collecting layer reduced polarization resistance {{{{ {R }_{p } }} but ohmic resistance {{{{ {R }_{1 } }} was relatively constant. After annealing of LSM cathode with Pt current collector at higher temperature polarization resistance {{{{ {R }_{p } }} was in-creased but ohmic resistance {{{{ {R }_{1 } }} was constant. These phenomena indicate that Pt or LSCo current col-lecting layers act as a catalytic layer for oxygen reduction of pure LSM cathode. LSCO current collector was effective in reducing the ohmic and polarization resistance of LSM-YSZ cathode.

• 한국수소및신에너지학회논문집
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• 제24권3호
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• pp.230-236
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• 2013

In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at $1400^{\circ}C$. The porous structure of LSM/GDC cathode substrate, after sintering at $1400^{\circ}C$, was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V, independent of testing temperature. The peak power densities were 116, 195 and $225mWcm^{-2}$ at 750, 800 and $850^{\circ}C$, respectively.

• 한국세라믹학회지
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• 제48권6호
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• pp.487-492
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• 2011

The effect of the application of lanthanum strontrium manganite and yttria-stabilized zirconia (LSM-YSZ) nano-composite fabricated by pulsed laser deposition (PLD) as a cathode of solid oxide fuel cell (SOFC) is studied. A gradient-structure thin-film cathode composed of 1 micron-thick LSM-YSZ deposited at an ambient pressure ($P_{amb}$) of 200 mTorr; 2 micron-thick LSM-YSZ deposited at a $P_{amb}$ of 300 mTorr; and 2 micron-thick lanthanum strontium cobaltite (LSC) current collecting layer was fabricated on an anode-supported SOFC with an ~8 micron-thick YSZ electrolyte. In comparison with a 1 micron-thick nano-structure single-phase LSM cathode fabricated by PLD, it was obviously effective to increase triple phase boundaries (TPB) over the whole thickness of the cathode layer by employing the composite and increasing the physical thickness of the cathode. Both polarization and ohmic resistances of the cell were significantly reduced and the power output of the cell was improved by a factor of 1.6.

• 한국세라믹학회지
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• 제53권5호
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• pp.494-499
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• 2016

In this work, the effects of different sintering inhibitors added to $La_{0.8}Sr_{0.2}MnO_{3-{\partial}}$ (LSM) were studied to obtain an optimum cathode material for cathode-supported type of Solid oxide fuel cell (SOFC) in terms of phase stability, mechanical strength, electric conductivity and porosity. Four different sintering inhibitors of $Al_2O_3$, $CeO_2$, NiO and gadolinium doped ceria (GDC) were mixed with LSM powder, sintered at $1300^{\circ}C$ and then they were evaluated. The phase stability, sintering behavior, electrical conductivity, mechanical strength and microstructure were evaluated in order to assess the performance of the mixture powder as cathode support material. It has been found that the addition of $Al_2O_3$ undesirably decreased the electrical conductivity of LSM; other sintering inhibitors, however, showed sufficient levels of electrical conductivity. GDC and NiO addition showed a promising increase in mechanical strength of the LSM material, which is one of the basic requirements in cathode-supported designs of fuel cells. However, NiO showed a high reactivity with LSM during high temperature ($1300^{\circ}C$) sintering. So, this study concluded that GDC is a potential candidate for use as a sintering inhibitor for high temperature sintering of cathode materials.

• 전기화학회지
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• 제2권4호
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• pp.202-208
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• 1999

[ $50/50 vol\%$ ] LSM-YSZ의 양극은 콜로이드 증착법에 의해 YSZ 전해질상에 증착하였다. 양극 특성은 주사전자현미경과 임피던스 분석기에 의해 고찰하였다. LSM-YSZ양극의 제조 조건에 따른 영향을 관찰하였으며, 그 영향에 대한 개선책이 고체산화물 연료전지의 성능향상을 위해 제시되었다. 임피던스에 대한 온도, YSZ전해질로의 양극 접착에 대한 표면 오염, 사용하는 Pt 페이스트, 미세구조에 대한 곡표면에 가해진 연무질 분사기술과 셀과 셀의 변동성에 대한 영향들은 각각 $900^{\circ}C$ 측정, YSZ표면 연마, 일단의 Pt페이스트 사용, 평편한 YSZ판의 사용과 일관된 절차와 기술의 사용에 의해 해결되었다. 이때 재현성 있는 임피던스 스펙트럼들이 향상된 셀을 사용함으로써 얻어졌고, $900^{\circ}C$에서 (공기)LSM-YSZ/YSZ/LSM-YSZ(공기) 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호로 구성되었다. 또한 LSM-YSZ 양극의 임피던스 특성은 촉매층, 양극 조성, 인가 전류 등과 같은 실험 조건들에 의해서도 영향을 받았다.

• 한국재료학회지
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• 제11권4호
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• pp.283-289
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• 2001

50/50 vol% LSM-YSZ (La$_{1-x}$Sr$_{x}$MnO$_3$-yttria stabilized zirconia)의 복합공기극이 콜로이드 증착법에 의해 연마된 YSZ 전해질상에 증착되었다. 그 전극 특성은 주사전자현미경, X선회절과 임피던스 분석기에 의해 연구되어졌다. 90$0^{\circ}C$에서 공기/LSM -YSZ/YSZ/Pt/공기 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호(depressed arc)로 구성되었다. LSM 전극에 대한 YSZ의 첨가는 전극내의 삼상계(TPB) 영역을 증가시켰으며, 이것이 LSM-YSZ 복합공기극의 비저항을 감소시켰다. 또한 전해질 표면의 불순물 제거와 TPB 길이의 증가를 위한 전해질 표면연마는 공기극의 비저항을 훨씬 더 감소시켰다. LSM-YSZ 공기극의 비저항은 작동온도, 공기극의 조성과 입자크기, 인가전류 및 전해질의 표면거칠기에 의해 큰 영향을 받았다.

• 한국세라믹학회지
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• 제47권1호
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• pp.75-81
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• 2010

The feasibility of using the thin film technology in utilizing lanthanum strontium manganite (LSM) for a solid oxide fuel cell (SOFC) cathode in a low-temperature regime is investigated in this study. Thin film LSM cathodes were fabricated using pulsed laser deposition (PLD) on anode-supported SOFCs with yttria-stabilized zirconia (YSZ) electrolytes. Although cells with a 1 ${\mu}m$-thick LSM cathode showed poor low-temperature cell performance compared to that of a cell with a bulk-processed cathode due to the lack of a triple-phase boundary length, the cell with 200 nm-thick gadolinia-doped ceria (GDC) inserted between the LSM and YSZ showed enhanced performance and more stable operation characteristics in a comparison of a cell without a GDC layer. We postulate that the GDC layer likely improved the cathode adhesion, therefore contributing to the improvement of the cell performance instead of serving as an interfacial reaction buffer.

• 대한기계학회논문집B
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• 제31권1호
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• pp.62-67
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• 2007

Optimization of cathode properties for intermediate temperature-operating SOFC (IT-SOFC) is carried out by using composite-type electrode structure in this study. Composite cathode may lower cathode overpotential by enhancing mixed ionic-electronic conductivity. In this study, particularly, LSM/YSZ, LSF/YSZ, LSCF/CGO, and PSC/CGO were selected as cathode materials. LSM/YSZ composite cathode showed the best performance of about 0.9${\Omega}cm^2$ at $700^{\circ}C$. It is inferred that the resistance is mainly affected by the reactivity between cathode and electrolyte which can cause the formation of resistive phases. Area specific resistance (ASR) characteristics were not changed significantly with decreasing sintering temperature of cathode, because reaction sites were increased even with worse adhesion of cathode on electrolytes.

• 한국세라믹학회지
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• 제36권9호
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• pp.982-990
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• 1999

YSZ/LSM composite cathode was fabricated by dip-coating of YSZ sol on the internal pore surface of a LSM cathode followed by sintering at low temperature (800-100$0^{\circ}C$) The YSZ coating significantly increased the TPB(Triple Phase Boundary) where the gas the electrode and the electrolyte were in contact with each other. Sinter the formation of resistive materials such as La2Zr2O7 or SrZrO3 was prevented due to the low processing temperature and TPB was increased due to the YSZ film coating the electrode resistance (Rel) was reduced about 100 times compared to non-modified cathode. From the analysis of a.c impedance it was shown that microstructural change of the cathode caused by YSZ film coating affected the oxygen reduction reaction. In the case of non-modified cathode the RDS (rate determining step) was electrode reactions rather than mass transfer or the oxygen gas diffusion in the experimental conditions employed in this study ($600^{\circ}C$-100$0^{\circ}C$ and 0,01-1 atm of Po2) for the YSZ film coated cathode however the RDS involved the oxygen diffusion through micropores of YSZ film at high temperature of 950-100$0^{\circ}C$ and low oxygen partial pressure of 0.01-0.03 atm.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2004년도 춘계학술발표대회 및 제6회 신소재 심포지엄
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• pp.52-52
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• 2004