• 신재생에너지
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• 제3권3호
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• pp.5-13
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• 2007

Stacks of solid oxide fuel cell with 1kW max power performance were designed on planar type employing anode-supported cells and metallic interconnects. The stacks composed of 3-cells, 8-cells, and 16-cells were fabricated and tested in serials by using anode-supported cells purchased from Indec, and sealants/interconnects prepared at RIST. In the performance test of the final 16-cells stack, OCV was recorded to be 16.7V. The peak power and the power density showed 1 kW, $0.77W/cm^2$ at $820^{\circ}C$, respectively. In addition, the long-term degradation rate of the power exhibited 2.25 % during 500h at $750^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제19권4호
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• pp.291-298
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• 2008

Carbon monoxide(CO) is one of the contamination source in reformed hydrogen fuel with an influence on performance of polymer electrolyte membrane fuel cell(PEMFC). The studies of CO injection presented here give information about poisoning and recovery processes. The aim of this research is to investigate cell performance decline due to carbon monoxide impurity in hydrogen. Performance of PEM fuel cell was investigated using current vs. potential experiment, long time(10 hours) test, cyclic feeding test and electrochemical impedance spectra. The concentrations of carbon monoxide were changed up to 10 ppm. Performance degradation due to carbon monoxide contamination in anode fuel was observed at high concentration of carbon monoxide. The CO gas showed influence on the charge transfer reaction. The performance recovery was confirmed in long time test when pure hydrogen was provided for 1 hour after carbon monoxide had been supplied. The result of this study could be used as a basis of various reformation process design and fuel quality determination.

• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.283-292
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• 2023

Currently, spray coating has attracted interest in the mass production of anode catalyst layers for proton exchange membrane water electrolysis (PEMWE). The solvent in the spray ink is a critical factor for the catalyst dispersion in ink, the microstructure of the catalyst layer, and the PEMWE performance. Herein, various pure organic solvents were examined as a substitute for conventional isopropanol-deionized water (IPA-DIW) mixture for ink solvent. Among the polar solvents that exhibited better IrO₂ dispersion over nonpolar solvents, 2-butanol (2-BuOH) was selected as a suitable candidate. The PEMWE single cells were fabricated using 2-BuOH at various ionomer contents, spray nozzle types, and drying temperatures, and their performance was compared to the cells fabricated using a conventional IPA-DIW mixture. The PEMWE single cells with 2-BuOH solvent showed good performances comparable to the conventional IPA-DIW mixture case and highly durable performances under accelerated degradation tests.

• Korean Chemical Engineering Research
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• 제46권2호
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• pp.286-290
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• 2008

고분자전해질 연료전지는 $60{\sim}80^{\circ}C$ 운전 온도에서 개질 가스에 약간의 일산화탄소만 있어도 백금 표면에 CO가 강하게 흡착하여 촉매기능을 방해한다. 본 연구에서는 일산화탄소를 산화시키기 위해 Ru/C 층(CO 필터)을 Pt/C 층과 가스 확산층(GDL) 사이에 위치 시켰다. Ru/C 필터는 PEMFC anode가 좋은 CO 내성을 갖게 했으나 Ru/C 필터 두께로 인한 물질전달 저항과 전하 전달 저항증가에 의한 단위전지 성능저하가 0.6 V에서 약 10% 있었다. 고분자막의 열화는 PEMFC 수명을 단축시키는 주요 원인이 되고 있다. 막 내구성은 전극의 촉매 종류에 영향을 받을 수 있다. 가속실험결과 Ru/C 촉매가 불소유출 속도를 향상시킴을 보임으로써 Ru/C 촉매 첨가가 PEMFC 수명을 단축시킬 수 있음을 보였다.

• 한국환경과학회지
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• 제18권1호
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• pp.61-72
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• 2009

Fabrication and oxidants production of 3 or 4 components metal oxide electrode, which is known to be so effective to destruct non-biodegradable organics in wastewater, were studied. Five electrode materials (Ru as main component and Pt, Sn, Sb and Gd as minor components) were used for the 3 or 4 components electrode. The metal oxide electrode was prepared by coating the electrode material on the surface of the titanium mesh and then thermal oxidation at $500^{\circ}C$ for 1h. The removed RhB per 2 min and unit W of 3 components electrode was in the order: Ru:Sn:Sb=9:1:1 > Ru:Pt:Gd=5:5:1 > Ru:Sn=9:1 > Ru:Sn:Gd=9:1:1 > Ru:Sb:Gd=9:1:1. Although RhB decolorization of Ru:Sn:Sb:Gd electrode was the highest among the 4 components electrode, the RhB decolorization and oxidants formation of the Ru:Sn:Sb=9:1:1 electrode was higher than that of the 3 and 4 components electrode. Electrogenerated oxidants (free Cl and $ClO_2$) of chlorine type in 3 and 4 components electrode were higher than other oxidants such as $H_2O_2\;and\;O_3$. It was assumed that electrode with high RhB decolorization showed high oxidant generation and COD removal efficiency. OH radical which is electrogenerated by the direct electrolysis was not generated the entire 3 and 4 components electrode, therefore main mechanism of RhB degradation by metal oxide electrode based Ru was considered indirect electrolysis using electrogenerated oxidants.

• 전기화학회지
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• 제5권2호
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• pp.62-67
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• 2002

용융탄산염 연료전지의 성능 저하와 수명 감소의 원인이 되는 부식 현상을 규명하고자 분리판 재료로 가장 널리 사용되고 있는 AISI-type 316L stainless steel을 대상으로 62Li/38K계 용융탄산염 내에서의 부식 실험을 수행하였다. 부식의 형태 및 속도는 환경에 의하여 다양하게 변화하게 되며, 용융탄산염 내에서 AISI-type 316L stainless steel의 부식 속도는 부식 반응에 의하여 형성되는 부동태 산화막의 안정성에 의하여 크게 영향을 받는다. 전기화학적 분극 거동을 분석한 결과 용융탄산염 연료전지의 anode가슨 분위기에서는 안정한 부동태 산화막이 형성되지 않았다. 순환 전압전류법과 정전위법을 이용한 부식 생성물의 X-ray분석을 통하여 특정한 전기화학적 전위 영역에서 반응기구와의 인과관계를 규명하고 다양한 형태의 부식 반응들을 분리해 내었다.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.229-235
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• 2003

A 50W class MCFC stack was operated in order to test a new design of the circular shaped separator. in the new design, the anode gas was supplied into the stack and was exhausted out of the stack after the anode reaction. The exhausted gas was reacted with the cathode gas supplied with excess oxygen in the vessel in which the stack was placed. Then the reacted gas flowed into the cathode side of the stack and was exhausted through the outlet located in the center of the stack. The average voltage of the single cells in the stack was 0.835V under the current density of $150mA/cm^2$, initially, and the degradation rate of the stack voltage was 1.7%/1,000h. High stack voltage with good stability of the present stack was due to the small temperature gradient in the stack. The small temperature gradient as well as the easiness of temperature control was the result of the new configuration of the separator which utilized the heat of the combustion reaction between anode outlet gas and the cathode inlet gas for heating the stack.

• 한국표면공학회지
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• 제56권1호
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• pp.62-68
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• 2023

Silicon (Si) is considered as a promising substitute for the conventional graphite due to its high theoretical specific capacity (3579 mAh/g, Li₁₅Si₄) and proper working voltage (~0.3V vs Li⁺/Li). However, the large volume change of Si during (de)lithiation brings about severe degradation of battery performances, rendering it difficult to be applied in the practical battery directly. As a one feasible candidate of industrial Si anode, silicon monoxide (SiO_x) demonstrates great electrochemical stability with its specialized strategy, downsized Si nanocrystallites surrounded by Li⁺ inactive buffer phase (Li₂O and Li₄SiO₄). Nevertheless, SiO_x inherently has the initial irreversible capacity and poor electrical conductivity. To overcome those issues, conformal carbon coating has been performed on SiO_x utilizing ethylbenzene as the carbon precursor of chemical vapor deposition (CVD). Through various characterizations, it is confirmed that the carbon is homogeneously coated on the surface of SiO_x. Accordingly, the carbon-coated SiOx from CVD using ethylbenzene demonstrates 73% of the first cycle efficiency and great cycle life (88.1% capacity retention at 50th cycle). This work provides a promising synthetic route of the uniform and scalable carbon coating on Si anode for high-energy density.

• 청정기술
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• 제22권1호
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• pp.16-28
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• 2016

섬유산업은 염색폐수의 농도가 높고 방출량이 많아 고도의 공해산업으로 알려져 있다. 염색폐수에는 색도물질 뿐만 아니라 다량의 유기화합물과 불용성 물질이 섞여 있다. 합성염료 중 아조(azo) 염료는 특히 오염물질의 배출이 많은 것으로 알려져 있다. 전기화학적 폐수처리방법은 전극의 산화·환원반응에 의해 색도와 유기물 등을 처리하는 방법으로 다른 폐수처리방법들에 비해 반응기가 작고 경제적이고 간단하며 오염물제거속도가 빠르다. 본 연구에서는 diazo 화합물인 CI Direct Blue 15 염색 폐수의 전기화학적 분해특성을 연구하였다. 실험은 전극재질과 조업조건을 달리하여 그에 따른 분해효율을 알아보고자 하였으며, 탈색 효율을 향상시킬 수 있는 최적전극 재질과 조업조건을 알아보고자 하였다. 조업조건으로는 전해질 농도, 전류밀도, 반응 온도, 초기 pH의 영향을 검토하였다. 음극은 stainless steel 전극을 사용하였고, 양극은 graphite와 RuO₂/Ti, PtO₂/Ti, IrO₂/Ti를 사용하여 조업조건에 따른 각 전극의 염색폐수 분해성능 실험을 수행하였다. 그 결과 전해질의 농도와 전류밀도 증가에 따라 전기분해 효율은 증가하였다. 양극 재질에 따른 전기분해 효율은 산성 전해질 조건에서 RuO₂/Ti > PtO₂/Ti > IrO₂/Ti > graphite 순이었고 중성과 염기성에서는 RuO₂/Ti > IrO₂/Ti > PtO₂/Ti > graphite의 순으로 나타났다. 따라서 염색 폐수의 전기분해 처리에는 RuO₂/Ti와 IrO₂/Ti가 가장 효율적인 양극재질이었다.

• 한국가시화정보학회지
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• 제19권2호
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• pp.56-62
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• 2021

Solid oxide fuel cells (SOFCs) is the high efficiency fuel cell operating at high temperatures ranging from 700-1000℃. Design of the flow paths of the fuel and air in SOFCs is important to improve cell performance and prevent cell degradation. However, the uneven distribution of current density in the traditional type having one inlet and outlet causes cell degradation. In this regard, the parallel flow path with two inlet and outlets was designed and compared to the traditional type based on computational fluid dynamics (CFD) simulation. To check the cell performance, hydrogen distribution, velocity distribution and current density distribution were monitored. The results validated that the parallel designs with two inlets and outlets have a higher cell performance compared to the traditional design with one inlet and outlet due to a larger reaction area. In case of uniform-type paths, more uniform current density distribution was observed with less cross-sectional variation in flow paths. In case of contracted and expanded inflow paths, significant improvement of performance and uniform current density was not observed compared to uniform parallel path. Considering SOFC cell with uniform current density can prevent cell degradation, more suitable design of SOFC cell with less cross-sectional variation in the flow path should be developed. This work can be helpful to understand the role of flow distribution in the SOFC performance.