• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.842-851
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• 2011

A multi-cell test system with 25 independent cells is used to test different electrode materials simultaneously for polymer electrolyte membrane fuel cells (PEMFCs). Twenty-five segmented membrane electrode assemblies (MEAs) having the same or different Pt-loading are prepared to analyze the performance deviation of cells in the multi-cell test system. Improvements in the multi-cell test system are made by ensuring that the system performs voltage sensing for the cells individually and inserting optimum gaskets between the MEAs and the graphite plates. The cell performances are improved and their deviations are significantly decreased by these modifications. The performance deviations changed according to various cell configurations because the operating conditions of the cells, such as the gas flow and concentration, differed. This cell system can be used to test multiple electrodes simultaneously because it shows relatively uniform performance under the same conditions as well as linear correlation with various catalyst loadings.

• Korean Chemical Engineering Research
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• 제52권2호
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• pp.175-181
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• 2014

고분자전해질 연료전지용 MEA(Membrane and Electrode Assembly)와 가축분뇨를 이용해 미생물연료전지(MFC)를 구동하였다. 여러 균을 혼합해 MFC를 구동했을 때 개별적으로 구동했을 때보다 높은 개회로전위(OCV)를 나타냈다. 돼지분뇨, 소분뇨, 닭분뇨, 오리 분뇨 중 돼지 분뇨를 이용했을 때 제일 높은 OCV 540mV를 보였다. 그리고 돼지분뇨에서 최고 $963mW/m^2$의 전력이 발생하였다. MFC 구동과정에서 MEA의 $Na^{2+}$, $Ca^{2+}$, $K^+$ 이온 및 불순물들에 의한 오염이 MFC의 낮은 성능의 한 원인임을 확인하였다.

• 전기화학회지
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• 제10권4호
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• pp.279-282
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• 2007

개질기에서 생산된 수소를 연료전지용 연료로 사용할 때에는 개질수소가 포함하고 있는 일산화탄소가 막-전극접합체의 촉매를 피독시켜서 연료전지 성능이 크게 감소된다. 본 논문에서는 개질수소에 포함된 일산화탄소가 스퍼터링 공정으로 제조된 박막층에 의하여 개선된 막-전극접합체의 성능에 어떠한 영향을 미치는지 연구하였다. 실험결과 Pt와 Ru박막은 MEA의 단위전지 성능을 개선하였으며, 금속박막은 막-전극접합체의 일산화탄소에 대한 내구성을 증가시켰다. 산화전극으로의 공기주입 운전기법은 막-전극접합체의 일산화탄소에 대한 내구성을 증가시켰다. 게다가 Pt, Ru그리고 PtRu박막은 공기주입 운전에 영향을 주는 것으로 확인되었다.

• 전기화학회지
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• 제14권1호
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• pp.50-55
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• 2011

Pt/C 촉매 (20, 40 wt% Pt/C)를 사용하여 고분자 전해질 연료전지의 MEA를 제조하고 각각의 촉매에서 최적의 나피온 이오노머 함량을 알아보았다. 나피온 함량에 따른 MEA의 전기화학적인 성능변화는 단위전지 성능평가, electrochemical impedance spectroscopy (EIS), cyclic voltammetry(CV)을 통해서 분석하였다. 나피온의 함량에 따라 전지의 활성화 분극, 옴 저항, 물질전달 저항 등의 변화가 나타났다. 이는 전극의 촉매층 내에서 발생되는 전기/이온 전도도 사이의 'trade-off'와 물질전달(물 배출과 반응가스 확산)에 의한 것이며, 대부분 활성화 분극과 물질전달 저항의 변화로 나타났다. 20 wt% Pt/C와 40 wt% Pt/C 촉매에서 최적의 나피온 함량은 각각 35 wt%와 20 wt%로 나타났다. 이는 Pt 중량비에 따른 Pt 입자간의 거리 및 촉매의 비표면적의 차이 때문에 나타난 결과이며 서로 다른 나피온 함량에서 최적의 삼상계면이 형성되는 것으로 판단된다.

• 자원리싸이클링
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• 제20권4호
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• pp.52-57
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• 2011

본 논문에서는 초음파나 교반 없이 전해질막과 확산층을 분리하기위한 새로운 방법에 대해 연구하였다. 증류수, 부탄올, 계면활성제를 이용하여 연료전지 막전극접합체의 전해질막과 확산층을 침지법으로 촉매입자의 분산 없이 분리하였다. 또한 분리된 확산층의 촉매와 연료전지 Pt/C 촉매를 왕수에서 $80{\sim}85^{\circ}C$로 가열하여 촉매입자를 녹여 침전제를 첨가하였다. 이후 소성하여 백긍 금속을 회수하였고 이는 새로운 연료전지용 전극촉매를 만드는데 사용될 것이다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.149-149
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• 2009

Generally, Nafion ionomer is used in the polymer electrolyte fuel cell (PEFC) electrodes to achieve high power density. At the high temperature operation of PEFC, however, ionic conductivity of Nafion remarkably decreased due to the evaporation of water in Nafion polymer. Recently, many researchers have focused on using the Ionic Liquids(ILs) instead of water in Nafion polymer. ILs have intrinsic properties such as good electrochemical stability, high ionic conductivity, and non-flammability. Especially, ILs play a crucial role in proton conduction by the Grottuss mechanism and act as water in water-free Nafion polymer. However, it was found that the ILs was leached out of the polymer matrix easily. In this study, we prepared membrane electrode assemblies with various contents of ILs. The effect of ILs in the electrode of each designed was investigated by a cyclic voltammetry measurement and the cell performance obtained through a single cell test using H2/Air gases. Electrodes with different contents of ILs in catalyst layer were examined at high temperature and low humidified condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1876-1878
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• 1999

Developed was a 5kW-class polymer electrolyte membrane fuel cell(PEMFC) system comprised of fuel cell stack, fuel processing, thermal and water management subsystems and ancillary equipments. Several large single cells have been fabricated with different gas flow field patterns and paths, and the gas flow field pattern for the stack has been determined based on the single cell performance of thin film membrane electrode assembly (MEA). The PEMFC stack was consisted of 100 cells with an electrode area of $300cm^2$, having serpentine flow pattern. Fuel processing was developed including an autothermal methanol reformer and two preferential CO oxidation reactors. The fuel processing was combined to PEMFC operation system consisted of air compressor and thermal and water management subsystems. The PEMFC stack showed performance of 5kW under the supply of $H_2$ and air, but its performance was lowered to 3.5kW under the supply of reformed gas.

• 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.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.86.2-86.2
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• 2010

In order to improve polymer electrolyte membrane fuel cell (PEMFC) durability, the durability of membrane electrode assemblies (MEA), in which the electrochemical reactions actually occur, is one of the vital issues. Many articles have dealt with catalyst layer degradation of the durability-related factors on MEAs in relation to loss of catalyst surface area caused by agglomeration, dissolution, migration, formation of metal complexes and oxides, and/or instability of the carbon support. Degradation of catalyst layer during long-term operation includes cracking or delamination of the layer which result either from change in the catalyst microstructure or loss of electronic or ionic contact with the active surface, can result in apparent activity loss in the catalyst layer. Membrane degradation of the durability-related factors on MEAs can be caused by mechanical or thermal stress resulting in formation of pinholes and tears and/or by chemical attack of hydrogen peroxide radicals formed during the electrochemical reactions. All of these effects, the mechanical damage of membrane and degradation of catalyst layers are more facilitated by uneven stress or improper MEA fabrication process. In order to improve the PEMFC durability, therefore, it is most important to minimize the uneven stress or improper MEA fabrication process in the course of the fabrication of MEA. We analyzed the effects of the MEA fabrication condition on the PEMFC durability with MEA produced using CCM (catalyst coated membrane) method. This paper also investigated the effects of MEA fabrication condition on the PEMFC durability by adding additional treatment process, hot pressing and pressing, on the MEA produced using CCM method.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.98.2-98.2
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• 2011

For optimal performance of a proton exchange membrane fuel cell (PEMFC), the membrane electrode assembly (MEA) requires hydration, and the membrane's conductivity depends on water content. A humidifier is required to ensure that the reactant gas, usually hydrogen and air, is hydrated before entering the fuel cell. Dry membrane operation or improper hydration causes performance degradation. Typically, the humidification of a fuel cell is carried out by means of an internal or external humidifier. A membrane humidifier is applied to the external humidification of transportation or residential power generation fuel cell due to its convenience and high performance. In this study, The experiments were constructed with a plate-type membrane humidifier in terms of geometric parameters and operating parameters. The results show that the temperature and pressure, the channel length, the membrane thickness and gas flow rate are critical parameters affecting the performance of the humidifier.