• Korean Chemical Engineering Research
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• 제50권2호
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• pp.187-190
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• 2012

고분자전해질연료전지(PEMFC)에서 음극 공기에 의한 이온오염은 막전극 합체(MEA)의 성능을 심각하게 열화시킨다. 본 연구에서는 산업단지, 길가, 해변의 공기 중 이온 농도를 측정하였다. 이들 지역에서 $Na^+$, $K^+$, $Ca^{2+}$와 $Fe^{3+}$ 이온 농도가 비교적 높았다. 가습수로부터 이들 이온이 cathode에 유입되어 MEA 성능에 미치는 영향에 대해 연구하였다. 수돗물을 가습수로 사용해 170시간 운전한 후 MEA 성능이 초기의 11%로 감소하였다. 이들 오염 이온들이 수소이온보다 전해질 막의 슬폰산기와 친화력이 더 강해 전해질 막에 쉽게 이온 교환된 결과다. MEA 중에서 전극/막 계면에서 이온 오염이 MEA 성능저하에 미치는 영향이 제일 컸다.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.1-6
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• 2024

상용차용 수소 전기 차량 수요가 증가하면서 고분자 전해질 연료전지 (PEMFC) 내구성은 승용차용보다 5배 이상 증가해야 하므로 내구성 향상 연구개발이 시급한 상황이다. PEMFC 막전극접합체 (MEA)가 화학적 열화가 진행되면 MEA 두께가 감소하고 핀홀이 발생하기도 한다. 본 연구에서는 화학적 열화 가속 실험인 개회로전압 (OCV) holding 후에 단위전지의 체결압을 상승시키면서 MEA의 성능 및 내구성의 변화를 측정하였다. 체결압이 상승하면서 고분자막의 저항과 막/전극 접촉저항이 감소하여 I-V 성능이 향상되었고, 수소투과도가 감소하였다. 수소투과도 감소에 따라 OCV는 증가하였다. 핀홀 부위를 제거하고 MEA 체결압을 증가시켰을 때 수소투과도가 급감하여 국부적인 열화가 전체 셀의 성능과 내구성에 미치는 영향이 큼을 확인하였다. 핀홀 부위 제거 후 재체결하고 OCV holding 평가를 하였을 때 막 저항과 수소투과도 감소에 따라 내구성이 향상됨을 확인하였다.

• Macromolecular Research
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• 제14권1호
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• pp.101-106
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• 2006

The transport of reactant gas, electrons and protons at the three phase interfaces in the catalytic layers of membrane electrode assemblies (MEAs) in proton exchange, membrane fuel cells (PEMFCs) must be optimized to provide efficient transport to and from the electrochemical reactions in the solid polymer electrolyte. The aim of reducing proton transport loss in the catalytic layer by increasing the volume of the conducting medium can be achieved by filling the voids in the layer with small-sized electrolytes, such as dendrimers. Generation 1.5 and 3.5 polyamidoamine (PAMAM) dendrimer electrolytes are well-controlled, nanometer-sized materials with many peripheral ionic exchange, -COOH groups and were used for this purpose in this study. The electrochemically active surface area of the deposited catalyst material was also investigated using cyclic voltammetry, and by analyzing the Pt-H oxidation peak. The performances of the fuel cells with added PAMAM dendrimers were found to be comparable to that of a fuel cell using MEA, although the Pt utilization was reduced by the adsorption of the dendrimers to the catalytic layer.

• 신재생에너지
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• 제17권2호
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• pp.50-58
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• 2021

We proposed an MEA development methodology that accurately measures intrinsic MEA performance while considering the uneven reaction environments formed inside a large-area BP. To facilitate measurement of the inherent MEA performance, we miniaturized the active area of the MEA to 3 cm², and prepared two MEAs with different ionomer contents of 0.65 and 0.80 (I/C). By simulating the operating conditions of a 100 cm² BP at the inlet (I), center (C), and outlet (O), the oxygen concentration and relative humidity were determined to be 20.7, 13.8, 11.7%, and 50, 66.1, and 70.1% respectively. We measured the performance and electrochemical analysis of the prepared MEAs under the three simulated conditions. Based on the results of statistical analysis of the evaluated MEA performance data, I/C 0.65 MEA had a higher average performance and lower performance deviation than I/C 0.80 MEA. Hence, it can be concluded that an I/C 0.65 MEA is a more effective MEA for large-area BP. Based on the above research process, we confirmed the effectiveness of the proposed MEA development methodology.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.335-340
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• 2016

Hydrogen production through proton exchange membrane water electrolysis (PEMWE) is expeditiously receiving international attention for renewable energy sources as well as energy storage system applications due to its environmentally friendly uses. A series of $Ir_{0.2}Ru_{0.8}O_2$ $Ir_{0.5}Ru_{0.8}O_2$ & $IrO_2$ catalysts were synthesized and electrochemically evaluated by using linear sweep voltammetry (LSV) technique. Furthermore, the PEMWE performances of full cells were evaluated by recording I-V Curves. The developed PEMWE stack was also operated in combination with a proton exchange membrane fuel cell (PEMFC) to demonstrate the discrete regenerative fuel cell (DRFC) performances. Produced hydrogen and oxygen from PEMWE were used as a fuel to operate PEMFC to establish a DRFC system.

• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.178-186
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• 2023

Three activation methods (constant voltage, current cycling, and hydrogen pumping) were applied to investigate the effects on the performance of the membrane electrode assembly (MEA) loaded with PtCo/C catalyst. The current cycling protocol took the shortest time to activate the MEA, while the performance after activation was the worst among the all activation methods. The constant voltage method took a moderate activation time and exhibited the best performance after activation. The hydrogen pumping protocol took the longest time to activate the MEA with moderate performance after activation. According to the distribution of relaxation time analysis, the improved performance after the activation mainly comes from the decrease of charge transfer resistance rather than the ionic resistance in the cathode catalyst layer, which suggests that the existence of water on the electrode is the key factor for activation.

• 신재생에너지
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• 제3권1호
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• pp.46-53
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• 2007

Direct Methanol Fuel Cell, DMFC is a potential power source for portable IT application. DMFC works at low temperature ($<100^{\circ}C$) without fuel processing. Methanol has high energy density, fuel economy, and easiness to handle. This paper focuses high efficient catalyst to increase utilization in the electrode, new membrane reducing methanol crossover, new material parts, and optimization of system integration. Lightweight and small-sized DMFC based on new materials, efficient stack, and improved system control will be applied to the 50W prototype system for the notebook computer.

• 전기화학회지
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• 제15권2호
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• pp.109-114
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• 2012

고분자전해질 연료전지 (PEMFC)의 공기극을 양극산화 알루미늄 (AAO) 템플레이트를 이용하여 제조하고 촉매층의 구조적 특성을 주사현미경 (SEM) 측정과 BET (Brunauer-Emmett-Teller) 분석을 통해 알아보았다. SEM 측정을 통해 일정한 크기와 모양의 Pt nanowire 가 규칙적으로 형성된 것을 확인할 수 있었다. BET 분석을 통해 AAO 템플레이트로 인하여 20-100 nm 크기의 기공 분포가 증가한 것을 확인하였다. 단위전지 성능평가와 임피던스 측정을 통하여 막-전극접합체 (MEA)의 전기화학적 특성을 분석하였다. 그 결과, AAO 템플레이트를 이용하여 제조한 MEA는 촉매층의 구조 개선으로 인하여 물질 전달 저항을 감소시킬 수 있었으며, 25%의 단위전지 성능이 향상되었다.

• Journal of Ceramic Processing Research
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• 제18권11호
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• pp.810-814
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• 2017

Proton exchange membrane fuel cells (PEMFCs) are some of the most efficient electrochemical energy sources for transportation applications because of their clean, green, and high efficiency characteristics. The optimization of catalyst layer morphology is considered a feasible approach to achieve high performance of PEMFC membrane electrode assembly (MEA). In this work, we studied the effect of the solvent on the catalyst layer of PEMFC MEAs fabricated using the electrostatic spray deposition method. The catalyst ink comprised of Pt/C, a Nafion ionomer, and a solvent. Two types of solvent were used: isopropyl alcohol (IPA) and dimethylformamide (DMF). Compared with the catalyst layer prepared using IPA-based ink, the catalyst layer prepared with DMF-based ink had a dense structure because the DMF dispersed the Pt/C-Nafion agglomerates smaller and more homogeneously. The size distribution of the agglomerates in catalyst ink was confirmed through Dynamic Light Scattering (DLS) and the microstructure of the catalyst layer was compared using field emission scanning electron microscopy (FE-SEM). In addition, the electrochemical investigation was performed to evaluate the solvent effect on the fuel cell performance. The catalyst layer prepared with DMF-based ink significantly enhanced the cell performance (1.2 A cm-2 at 0.5 V) compared with that fabricated using IPA-based ink (0.5 A cm-2 at 0.5 V) due to the better dispersion and uniform agglomeration on the catalyst layer.

• 자원리싸이클링
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• 제21권3호
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• pp.15-20
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• 2012

본 논문에서는 연료전지 막전극접합체에서 막분리 및 염산침출법을 이용하여 백금과 루테늄을 침출하는 연구를 하였다. 증류수, 10 vol.% 부탄올 용액, 15 vol.% 양이온 계면활성제(Koremul-LN-7)를 이용하여 연료전지 막전극접합체의 전해질막과 확산층을 침지법으로 촉매입자의 분산 없이 분리하였다. 그리고 질산 또는 과산화수소를 산화제로 하고 사용하는 염산에 의해 분리된 가스확산층의 촉매에 함유된 백금과 루테늄 금속을 침출하는 연구를 하였다. 과산화수소를 산화제로 사용하였을 때 백금과 루테늄의 침출율이 더 높았으며 최적 조건은 $90^{\circ}C$에서 염산 농도 8 M, 과산화수소 첨가량 5 M, 침출시간 6시간이었다. 이 조건에서 백금의 침출률은 98%, 루테늄의 침출율은 71.5%였다.