• Proceedings of the Membrane Society of Korea Conference
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• 2004.05b
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• pp.57-60
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• 2004

Polymer electrolyte membranes have been studied widely in chloro-alkali electrolysis, cationic exchange resins, and fuel cell applications. Especially, sulfonated polyimide membranes have been suggested as a potential polymer electrolyte in PEMFC due to their excellent thermal stability and high proton conductivity.(omitted)

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.233-238
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• 1999

고분자 연료전지 (polymer electrolyte membrane fuel cell (PEMFC)) 시스템은 연료전지 스택, 연료공급부, 공기공급부, 냉각부, 운전 제어부, 전자부하 및 데이터 획득부 그리고 인버터 등으로 구성된다. 이 가운데 가장 중요한 구성요소인 고분자 연료전지 스택의 성능은 전극과 전해질막 접합체의 성능뿐만 아니라 스택의 구조와 유로형상에도 크게 의존한다. 따라서 보다 고성능의 전해질막과 전극을 개발하고 소형화, 경량화가 가능한 스택의 구조와 유로형상을 찾는 것이 고분자 연료전지 스택의 개발에 있어 매우 중요하다.(중략)

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.4
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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.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.235-238
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• 2005

Sulfonated poly(ether sulfone) copolymers (PESs) were synthesized using hydroquinone 2-potassium sulfonate (HPS) with other monomers (bisphenol A and 4-fluorophenyl sulfone). PESs with different $mole\%$ of hydrophilic group were prepared by changing the mole ratio of HPS in the polymerization reaction. The chemical structure and the thermal stability of these polymers were characterized by using $^1H-NMR$, FT-IR and TGA techniques. The PES 60 membrane, which has $60 mole\%$ of HPS unit in the polymer backbone, has a proton conductivity of 0.091 S/cm and good insolubility in boiling water. The TGA showed that PES 60 was stable up to $272^{\circ}C$ with a char yield of about $29\%\;at\;900^{\circ}C\;under\;N_2$ atmosphere. To investigate the single cell performance, the catalyst coated PES 60 membrane was used and a single cell test was carried out using $H_2/O_2$ gases as fuel and oxidant at various temperatures. We observed that the cell performance was enhanced by increasing the cell temperature. A current density of $1400 mA/cm^2$ at 0.60 V was obtained at $70^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.41-55
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• 2018

General polymer electrolyte fuel cell (PEMFC) operates at less than $80^{\circ}C$. Therefore liquid phase water resulting from electrochemical reaction accumulates and floods the cell which in turn increases the mass transfer loss. To prevent the flooding, it is common to employ serpentine flow channel, which can efficiently export liquid phase water to the outlet. The major drawback of utilizing serpentine flow channel is the large pressure drop that happens between the inlet and outlet. On the other hand, in the high temperature polymer electrolyte fuel cell (HT-PEMFC), since the operating temperature is 130 to $180^{\circ}C$, the generated water is in the state of gas, so the flooding phenomenon is not taken into consideration. In HT-PEMFCs parallel flow channel with lower pressure drop between the inlet and outlet is employed therefore, in order to circulate hydrogen and air in the cell less pumping power is required. In this study we analyzed HT-PEMFC's different flow channels by parallel computation using previously developed 3-D isothermal model. All the flow channels had an active area of $25cm^2$. Also, we numerically compared the performance of HT-PEMFC parallel flow channel with different manifold area and Rib interval against the original serpentine flow channel. Results of the analysis are shown in the form of three-dimensional contour polarization curves, flow characteristics in the channel, current density distribution in the Membrane, overpotential distribution in the catalyst layer, and hydrogen and oxygen concentration distribution. As a result, the performance of a real area fuel cell was predicted.

• Membrane Journal
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• v.26 no.1
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• pp.1-13
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• 2016

Fuel cells are regarded as a representative energy source expected to replace fossil fuels particularly used in internal combustion engines. One of the most important components is polymer electrolyte membranes (PEMs) acting as a proton conducting barrier to prevent fuel gas crossover. Since water channels act as proton pathways through PEMs, many researchers have been focused on the 'good phase-separation of hydrophilic moiety' which ensures high water retention under low humidity enough to keep the water channel for good proton conduction. Here, we summarized the strategies which have been adopted to synthesize sulfonated PEMs having high proton conductivities even under low humidified conditions, and hope this review will be helpful to design high performance hydrocarbon PEMs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.400-407
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• 2011

The stress distribution and stress amplitude of a membrane are major factors to decide the mechanical fatigue life of PEMFC (Polymer Electrolyte Membrane Fuel Cell). In this paper, mechanical stresses under operating hygro-thermal condition of the membrane are numerically modelled. Contact analysis between gas diffusion layer (GDL) and the membrane is performed under various temperature-humidity conditions. The structural model has nonlinear material properties depending on temperature and relative humidity. Several geometric conditions are applied to the model. The numerical analysis results indicate that deformations of the membrane are strongly related with assembly conditions of the fuel cell. The fatigue life is predicted for practical operating condition through experimental data.

• Journal of the Korean Applied Science and Technology
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• v.28 no.4
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• pp.497-501
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• 2011

Polymer electrolyte membrane fuel cell (PEMFC) performance degrade when sulfur dioxide is present in the fuel hydrogen gas, this is referred as $SO_2$ poisoning. This paper reveals $SO_2$ poisoning on PEMFC cathode part by measuring electrical performance of single cell under 1 ppm and 5 ppm on $SO_2$ gas operating. The security of $SO_2$ poisoning depended on $SO_2$ concentration under the best operating conditions($65^{\circ}C$ of cell temperature and 100% of relative humidity between anode and cathode). $SO_2$ adsorption occured on the surface of catalyst layer on membrane electrode assembly (MEA), In addition, MEA poisoning by $SO_2$ was cumulative but reversible. After poisoning within 5 ppm $SO_2$ for 1hr, the electrical performance of PEMFC was found to recover up to about 93% by cyclic voltametry scan.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.3
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• pp.43-48
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• 2002

In this study, high performance electrode catalyst was developed in fabrication of membrane electrode assembly for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). The I-V characteristics were measured to evaluate the influence of Nafion solution and Pt loading amount in the catalyst composition. The electrode characteristics were also investigated with respect to temperature change. The electrode performance was optimized at Nafion 5 wt% and 0.5 mg Pt/$\textrm{cm}^2$ content. The increase in the concentration of Nafion solution resulted in the decrease in electrode performance. At $80^{\circ}C$ of unit cell, I-V characteristics excelled those obtained at lower temperature. There was no difference in performance at low current density, but the improvement of voltage value in higher temperature could be found at high current density.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.281-283
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• 2005

Water management in polymer electrolyte membrane fuel cells(PEMFCs) is one of the most challenging issues. Freeze start-up in the automotive applications is also important research topic in the PEMFC field. Transportation of proton and separation of reactant gases are main roles of polymer electrolyte membranes. It has been known that water in the membrane conducts as a vehicle for the proton transportation. At sub-zero temperature, the frozen water blocks the access of reactant gases to the active sites of electrode as well as occurs the physical destruction of fuel cell structures. In this study, property changes of electrolyte membranes in the freeze conditions $(at\;-25^{\circ}C)$ were investigated. For the various amount of water contained membranes, the property changes, especially for the proton conductivity, were observed after several times of freeze/thaw$(-25\~80^{\circ}C)$ cycle.