• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.552-557
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• 2012

In this study, we have coated the inner surface of YSZ channel using LSM powder ink through depressurization process for making the cathode of a stacked planar-type SOFC module. To coat the surface of YSZ channel uniformly, we tried to find the optimum manufacturing condition for LSM ink. We used four different dispersants (BYK series) and two different solvents (ethanol and DMF) to make the LSM ink. It was revealed that the ink made with the ethanol solvent and the BYK-111 dispersant has the lowest viscosity, relatively low contact angle and most excellent dispersibility. After depressurizing a chamber filled with LSM ink and sintered YSZ channel, we have found that the YSZ channel was uniformly coated with LSM cathode. The LSM ink with 25 vol% BYK-111 showed the most uniform coating.

• E2M - 전기 전자와 첨단 소재
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• 제9권9호
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• pp.949-953
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• 1996

In this paper, the cathode materials of solid oxide fuel cell were fabricated, and the analysis of TG/DTA, XRD, thermal expansion and electric conductivity were investigated. As a result, thermal expansion coefficient of LSM was not quite different from that of electrolyte. And the performance of LSM(x=0.4) was more excellent than the others.

• 전기화학회지
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• 제8권2호
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• pp.88-93
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• 2005

고체산화물 연료전지의 작동온도를 낮추고 셀의 출력 밀도를 향상시키기 위해 연료극 지지체식 셀을 제조하고 공기극의 구조를 개선시켜 그 특성을 조사 분석하였다. 셀 제조는 습식법에 의해 이루어졌으며, 제조된 연료극 지지체상에 전해질을 코팅하고 최종적으로 공기극을 코팅하였다. 제조된 셀은 $8mol\%\;V_2O_3$로 안정화된 $ZrO_2(YSZ)$ 전해질 층 및 Ni/YSZ 연료극 지지체로 이루어졌으며, 공기극은 $(La_{0.85}Sr_{0.15})_{0.9}MnO_{3-x}(LSM),\;LSM/YSZ(LY)$ 복합체, $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3{LSCF)$를 두층 또는 3층으로 두께를 변화시키면서 코팅하였다 임피던스로 전기화학적 특성을 조사하였으며, $3\%$수분을 함유한 수소와 공기로 $800^{\circ}C$ 이하에서 단전지의 성능을 평가하였다 작동온도 $800^{\circ}C$에서, $LY\;9{\mu}m/LSM\;9{\mu}m/LSCF\;17{\mu}m$의 다층이 코팅된 전지가 $590mW/cm^2$로 가장 좋은 성능을 나타냈으며, $0.244{\Omega}cm^2$로 가장 작은 분극저항을 가졌다. 측정된 임피던스 결과, 공기극의 분극저항이 3층 코팅된 셀의 경우 가장 작게 나타났음을 확인하였으며, 이것은 LY복합전극에 의한 전극 계면 저항 감소뿐 만 아니라 LSCF에 의한 공기극의 산소환원 반응의 전하이동 저항이 감소하였기 때문인 것으로 해석된다.

• 한국세라믹학회지
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• 제38권1호
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• pp.93-99
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• 2001

(La,Sr)MnO$_3$(LSM)-YSZ 복합체 양극에 있어서 소결온도 및 전극두께와 cathodic potential이 전극 특성에 미치는 영향을 고찰하였다. 양극의 소결은 삼상계면의 양을 결정하는 중요한 변수로 LSM 단미 양극과 YSZ가 40 wt% 포함된 LSM-YSZ 복합체 양극 모두 120$0^{\circ}C$에 소결했을 때 가장 낮은 분극저항을 나타내었다. 또한 양극 후막의 두께가 얇아지면 양극의 in-plane 저항이 증가하여 ohmic 저항이 증가하였는데, LSM-YSZ 복합체 양극의 경우 약 30$mu extrm{m}$ 정도의 전극두께가 가장 효과적인 전극 특성을 나타내었다. 한편, LSM-YSZ 복합체 양극에 -0.5 V의 cathodic potential을 인가함에 따라 양극에서 일어나는 산소환원반응의 활성이 증가하였는데, 1가 산소이온의 표면확산반응의 분극저항은 감소하였으나, 고주파수 영역에서 나타나는 산소이온전달반응의 저항은 거의 변화하지 않았다. 이것은 Mn의 환원에 의한 양극표면에 생성된 산소공공에 기인한다.

• 한국세라믹학회지
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• 제37권3호
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• pp.227-232
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• 2000

The LSM-YSZ composite electrode as a mixture of LSM and YSZ shows percolation characteristics. It was identified that the polarization resistance of LSM-YSZ composite electrode depend on YSZ connectivity by changing powder size ratio of the DLSM/DYSZ. That is, YSZ in composite electrode showed low electrochemical activity without YSZ connectivity. However, the polarization resistance decreased abruptly with YSZ connectivity due to high electrochemical activity of YSZ in composite electrode. Because the amount of three phase boundary is dependent on LSM and YSZ particle size, the polarization resistance of cathode decreases as LSM and YSZ particle size decreases.

• 에너지공학
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• 제19권2호
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• pp.73-80
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• 2010

고체산화물연료전지(SOFC)는 청정에너지기술로써 화학에너지를 전기에너지로 직접 전환한다. SOFC는 열병합발전과 결합하여 80%이상의 효율을 올릴 수 있으며 천연가스와 바이오가스 등 연료에 대한 융통성이 폴리머전해질막연료전지(PEMFC)보다 높다. YSZ전해질과 함께 SOFC에 주로 채용되는 공기극 재료는 아직까지 Sr이 첨가된 $LaMnO_3$(LSM)이다. LSM 이외에, 혼합전도성을 가지는 페로브스카이트로서 Sr첨가 $LaCoO_3$(LSCo), $LaFeO_3$(LSF), $LaFe_{0.8}Co_{0.2}O_3$(LSCF)는 공기극 임피던스가 LSM에 비해 현저히 낮아 연구가 증가하고 있다. 그러나 SOFC전극의 소결온도에서 YSZ과 고체반응을 일으키는 문제점과 열팽창 계수가 YSZ와 격차가 크게 나는 문제점 때문에 전극 제조가 복잡하다. 따라서 전해질과의 화학적 안정성 및 유사한 열팽창계수(TEC)를 가지면서 우수한 전기화학활성을 제공하는 것이 해결해야할 중요한 문제로 남는다.

• 한국세라믹학회지
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• 제51권4호
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• pp.278-282
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• 2014

Due to high ionic conductivity and favorable oxygen electrocatalysis, doped $Bi_2O_3$ systems are promising candidates as solid oxide fuel cell cathode materials. Recently, several researchers reported reasonably low cathode polarization resistance by adding electronically conducting materials such as (La,Sr)$MnO_3$ (LSM) or Ag to doped $Bi_2O_3$ compositions. Despite extensive research efforts toward maximizing cathode performance, however, the inherent catalytic activity and electrochemical reaction pathways of these promising materials remain largely unknown. Here, we prepare a symmetrical structure with identically sized $Y_{0.5}Bi_{1.5}O_3$/LSM composite electrodes on both sides of a YSZ electrolyte substrate. AC impedance spectroscopy (ACIS) measurements of electrochemical cells with varied cathode compositions reveal the important role of bismuth oxide phase for oxygen electrocatalysis. These observations aid in directing future research into the reaction pathways and the site-specific electrocatalytic activity as well as giving improved guidance for optimizing SOFC cathode structures with doped $Bi_2O_3$ compositions.

• 한국전기전자재료학회논문지
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• 제11권1호
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• pp.18-25
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• 1998

G $d_{0.2}$C $e_{0.8}$ $O_{1.9}$(CGO) for electrolyte and L $a_{0.5}$S $r_{0.5}$Mn $O_3$(LSM50) for cathode in Solid Oxide Fuel Cells(SOFC) were synthesized by citrate process. Specimens were prepared with sintering temperatures at 110$0^{\circ}C$, 120$0^{\circ}C$ and 130$0^{\circ}C$, which were fabricated by slurry coating with citric acid contents. Interfacial resistance was measured between cathode and electrolyte using AC-impedance analyzer. With various citric acid content, the degree of agglomeration for the initial particles changed. Also sintering temperature changed the particle size and the degree of densification of cathode. Factors affecting the interfacial resistance were adherent degree of the electrolyte and cathode, distribution of TPB(three phase boundaries, TPB i.e., electrolyte/electrode/gas phase area) and porosity of cathode. By increasing the sintering temperature, particle size and densification of the cathode were increased. And then, TPB area which occurs catalytic reaction was reduced and so interfacial resistance was increased.sed.sed.d.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.373-380
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• 2001

Solid Oxide Fuel Cells (SOFCs) have received considerable attention because of the advantages of high effiiciency, low pollution, cogeneration application and excellent integration with simplified reformer In this paper, we reported development of anode-tubular SOFC by wet process. For making tubular cell, Ni-cermet YSZ anode tube was fabricated using extrusion process, and YSZ electrolyte layer and LSM-YSZ composite, LSM, LSCF cathode layer were coated onto the anode supported tube using slurry dipping process and sintered by co-firing process. By using this tubular cell, we fabricated single cell consisted of the various cathode layers and 4 cell stack with an effective area of $75 cm^2$ per single cell, and evaluated their performance characteristics.

• 한국세라믹학회지
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• 제44권12호
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• pp.715-719
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• 2007

STS444 with or without $La_{0.9}Sr_{0.1}MnO_3$ (LSM)-coating was contacted to $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_3$ (LSCF) cathode on various electrolyte materials and the polarization resistance $(R_p)$ was measured by impedance spectroscopy. By making a symmetric half-cell and contacting only one side of the cathode with the interconnect, the effect of chromium (Cr) poisoning was separated from the aging effects. When the LSCF cathode was contacted with LSM-coated STS (stainless steel), $R_p$ of LSCF was lower than that contacted with the uncoated STS. Impedance patterns measured for the working electrode (W.E.), the counter electrode (C.E.) at $600^{\circ}C$ in air were analyzed. Normalized data of net Cr effect showed that $Ce_{0.9}Gd_{0.1}O_2$ (GDC) electrolyte is more tolerant to the chromium poisoning than $La_{0.9}Sr_{0.1}Ga_{0.8}Mg_{0.2}$ (LSGM) or 8 mol% $Y_2O_3-doped$ $ZrO_2$ (YSZ) electrolytes.