• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.16-21
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• 2008

The key component of a direct methanol fuel cell (DMFC) is the membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane and catalyst layers (anode and cathode electrode). Generally the catalyst layer is coated on the porous electrode supporter (e.g. carbon paper or cloth) using various coating methods such as brushing, decal transfer, spray coating and screen printing methods. However, these methods were disadvantageous in terms of the uniformity of catalyst layer thickness, catalyst loss, and coating time. In this work, we used bar-coating method which can prepare the catalyst layer with uniform thickness for MEA of DMFC. The surface and cross-section morphologies of the catalyst layers were observed by SEM. The performances and resistance of the MEAs were investigated through a single cell evaluation and impedance analyzer.

• Membrane Journal
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• v.19 no.2
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• pp.89-95
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• 2009

A comb-like copolymer consisting of a poly(vinyl chloride) backbone and poly(hydroxy ethyl acrylate) side chains, i.e. PVC-g-PHEA, was synthesized through atom transfer radical polymerization (ATRP). This comb-like copolymer was crosslinked with 4,5-imidazole dicarboxylic acid (IDA) via the esterification of the -OH groups of PHEA in the graft copolymer and the -COOH groups of IDA. Upon doping with phosphoric acid (PA, $H_3PO_4$) to form imidazole-PA complexes, the proton conductivity of the membranes continuously increased with increasing PA content. A maximum proton conductivity of 0.011 S/cm was achieved at $100^{\circ}C$ under anhydrous conditions. The PVC-g-PHEA/IDA/PA complex membranes exhibited good mechanical properties, i.e. 575 MPa of Young's modulus, as determined by a universal testing machine (UTM). Thermal gravimetric analysis (TGA) shows that the membranes were thermally stable up to $200^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.82.1-82.1
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• 2011

최근 국내에서 발생된 대규모 정전사태로 인해 안정적인 전력공급에 대한 국민들의 요구가 커져, 지난 3월 일본 후쿠시마 원전사고 이후 다시 한번 분산전원에 대한 필요성이 대두되어지고 있다. 여러 분산전원 중 연료전지는 다른 에너지원에 비해 에너지의 지속성이 우수하여 가장 안정적인 분산전원 형태의 하나이다. 이에 따라 국내의 경우 우수한 도시가스 인프라로 인해 건물용 연료전지라는 신기술에 대한 국민의 수용성은 점점 높아질 것으로 기대된다. 현재 건물용 연료전지의 경우, 주로 1kW급 연료전지가 시범보급되어 각 가정에 설치되어지고 있으나, 상가, 주유소 및 편의점 등의 상업시설과 생활관 및 소형빌라 등의 집단 주거시설 같은 1kW급 보다 용량을 더 필요로 하는 응용처에 국내에서 개발된 5kW급 연료전지시스템이 적용되어지기를 기대한다. 본 연구에서는 국내 제작된 5kW급 고분자전해질 연료전지시스템의 보급이전에 안전성능 평가를 통해 시스템의 성능 및 안전성 평가결과를 제조사에 피드백 하여 5kW급 건물용 연료전지시스템의 조기 상업화에 앞장서고자 한다. 5kW급 연료전지시스템의 기술개발은 핵심부품인 연료변환기, 스택 및 BOP 기술의 경우 1kW급 연료전지시스템에 적용된 것과는 다른 기술이 필요하고, 단순한 scale-up 과정이 아닌 새로운 기술개발로 제품에 적용시켜야 하는 난점을 가지고 있다. 특히, 연료변환기의 경우 연료 유량의 증가로 인하여 reformer, CO shift 및 Prox 반응기의 유체역학, 열교환 흐름 및 촉매반응 공학적으로 이론을 응용한 새로운 반응기 설계와 제작기술 확립이 선행되어 전체적인 시스템 제작 설계에 반영되어져야 한다. 그러므로 본 연구에서는 연료전지시스템 안전성능 평가를 위해 용량증대에 따른 안전성평가 항목을 검토하고, 5kW급 연료전지시스템평가를 수행하여 시스템의 제품성능, 작동성능 및 계통연계성능에서의 안전성을 확인하였고, 정전 유풍과 같은 이상조건 및 실외 환경에 대한 시스템의 안전성도 확인하였다. 또한 부하운전 조건을 75% 및 50%로 변화시켰을 때 빠른 응답시간과 안정적인 부하변동운전을 확인하였다.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.536-541
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• 1998

The porous size alumina membrane was prepared by anodic oxidation with current method in an aqueous solution of oxalic acid. The aluminum metal plate was pretreated with thermal oxidation, chemical polishing and electropolishing before anodic oxidation. Membrane thickness and pore size distribution were investigated with several anodizing conditions; reaction temperature, cumulative charge, electrolyte concentration and current density. The porous alumina membrane obtained was $55{\sim}75{\mu}m$ thick with straight micropore of 45~100nm. Also, the porous alumina membrane has an uniform pore diameter and pore distribution. It was inorganic ultrafiltration membrane as a kind of the ceramic membrane.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.118-124
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• 2017

An air cooling, open cathode type polymer electrolyte membrane fuel cell (PEMFC) has the advantages of system simplification and cost effectiveness. Open cathode PEMFC could suffer from reduced performance due to the membrane dehydration in low humidity of air. Effects of the cathode air flow rate, anode purge interval and long term storage on PEMFC performance were investigated in this work. Fan voltage is an important factor on air cooling PEMFC performance because the cathode air flow rate and stack temperature were controlled by fan voltage. The dead ended anode (DEA) method was applied to increase hydrogen usage. Periodical purge was used to discharge accumulated water and gas. The influence of long term non-operating condition on PEMFC performance degradation due to the membrane dehydration was also studied and the quick recovery method was developed.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.173-178
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• 2011

Separator of stack in polymer electrolyte membrane fuel cell (PEMFC) is high cost and heavy. If we make it low cost and lighter, it will have a great ripple. In this study, low carbon steel is used as base metal of separator because the cost of low carbon steel is very cheaper commercial metal material than stainless steels, which is widely used as separator. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon steel needs to be surface treated. We made Chromium electroplated layer of $5{\mu}m$, $10{\mu}m$ thickness on the surface of low carbon steel and it was nitrided for 2 hours at $1000^{\circ}C$ in a furnace with 100 torr nitrogen gas pressure. Cross-sectional and surface microstructures of surface treated low carbon steel are investigated using SEM. And crystal structures are investigated by XRD. Interfacial contact resistance and corrosion tests were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1 N $H_2SO_4$ + 2 ppm $F^-$ solution at $80^{\circ}C$. Throughout this research, we try to know that low carbon steel can be replaced stainless steel in separator of PEMFC.

• Transactions of the Korean hydrogen and new energy society
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• v.19 no.5
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• pp.403-409
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• 2008

Polymer electrolyte membrane fuel cell (PEMFC) is very interesting power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, improvement of performance, effect of temperature and initial start at low temperature. These problems can be approached to be solved by using experiment and mathematical method which are general principles for analysis and optimization of control system for heat and hydrogen detecting management. In this paper, insulation vessel and control system for stable operation of fuel cell at low temperature were developed for experiment. The constant temperature capability and the heating time at sub-zero temperatures with insulation control system were studied by using a heating bar of 60W class. PEMFC stack which was made by 4 cells with $50\;mc^2$ active area in each cell is a thermal source. Times which take to reach constant temperature by the state of insulation vacuum were measured at variable environment temperatures. The test was performed at two conditions: heating mode and cooling mode. Constant temperature capability was better at lower environment temperature and vacuum pressure. The results of this experiment could be used as basis data about stable operation of fuel cell stack in low temperature zone.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.471-480
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• 2017

A proton exchange membrane fuel cell (PEMFC) operated at $150^{\circ}C$ was evaluated by a controlling different amount of phosphoric acid (PA) to a membrane-electrode assembly (MEA) without humidification of the cells. The effects on MEA performance of the amount of PA in the cathode are investigated. The PA content in the cathodes was optimized for higher catalyst utilization. The highest value of the active electrochemical area is achieved with the optimum amount of PA in the cathode confirmed by in-situ cyclic voltammetry. The current density-voltage experiments (I-V curve) also shows a transient response of cell voltage affected by the amount of PA in the electrodes. Furthermore, this information was compared with the production variables such as hot pressing and vacuum drying to investigate those effect to the electrochemical performances.

• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.181-185
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• 2010

Polyaniline-ionic liquid composite was prepared and investigated its physical and electrochemical properties. The quasi-solidification was presented in imidazolium-based ionic liquid (1-methly-3-propylimidazolium iodide, PMI-I) containing above 30 wt% of polyaniline (emeraldine base), which exhibited around 80% decrease of conductivity compared to pristine ionic liquid, resulting in fibril structure trough ${\pi}-{\pi}$ self-assembled of imidazolium aromatic ring of ionic liquid on polyaniline framework.

• Carbon letters
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• v.11 no.1
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• pp.38-40
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• 2010

Carbon supported electrocatalysts are commonly used as electrode materials for polymer electrolyte membrane fuel cells(PEMFCs). These kinds of electrocatalysts provide large surface area and sufficient electrical conductivity. The support of typical PEM fuel cell catalysts has been a traditional conductive type of carbon black. However, even though the carbon particles conduct electrons, there is still significant portion of Pt that is isolated from the external circuit and the PEM, resulting in a low Pt utilization. Herein, new types of carbon materials to effectively utilize the Pt catalyst are being evaluated. Carbon nanofiber/activated carbon fiber (CNF/ACF) composite with multifunctional surfaces were prepared through catalytic growth of CNFs on ACFs. Nickel nitrate was used as a precursor of the catalyst to synthesize carbon nanofibers(CNFs). CNFs were synthesized by pyrolysising $CH_4$ using catalysts dispersed in acetone and ACF(activated carbon fiber). The as-prepared samples were characterized with transmission electron microscopy(TEM), scanning electron microscopy(SEM). In TEM image, carbon nanofibers were synthesized on the ACF to form a three-dimensional network. Pt/CNF/ACF was employed as a catalyst for PEMFC. As the ratio of prepared catalyst to commercial catalyst was changed from 0 to 50%, the performance of the mixture of 30 wt% of Pt/CNF/ACF and 70wt% of Pt/C commercial catalyst showed better perfromance than that of 100% commercial catalyst. The unique structure of CNF can supply the significant site for the stabilization of Pt particles. CNF/ACF is expected to be promising support to improve the performance in PEMFC.