• Korean Chemical Engineering Research
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• 제51권3호
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• pp.370-375
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• 2013

상업용 막전극접합체를 사용하여 제작한 고분자전해질 연료전지의 CO poisoning 및 air bleeding 효과가 스택의 셀전압 성능에 미치는 영향을 분석하였다. 실험을 통해 확보한 동적 응답 데이터에 일차 미분방정식으로 표현되는 일차계 모델을 적용하여 정상상태 이득과 시간상수를 계산하는 방법으로 스택 셀전압의 응답 특성을 정량화하였다. 연료전지 개질기로부터 공급되는 개질 가스에 포함된 CO 농도가 1 ppm 증가할 때마다 셀전압은 1.3~1.6 mV 저하되고, CO 농도의 변화폭이 클수록 정상상태에 도달하기까지 걸리는 시간이 점점 짧아지는 것으로 분석되었다. CO poisoning에 의해 저하된 스택 성능을 회복시키기 위해 air bleeding을 수행할 경우, 주입하는 공기의 농도를 증가시킬수록 셀전압 상승폭(정상상태 이득)이 커지고 회복시간(시간상수)은 짧아지나, 1% 수준의 air bleeding만으로도 CO poisoning이 일어나기 전 셀전압의 87%~96%를 1~30 min 이내에 회복시킬 수 있는 것으로 분석되었다.

• 한국수소및신에너지학회논문집
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• 제17권2호
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• pp.149-157
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• 2006

Hydrogen as new energy sources is highly efficient and have very low environmental emissions. The proton exchange membrane fuel cell (PEMFC) is an emerging technology that can meet these demands. Therefore, the preparation of stable polymeric membranes with good proton conductivity and durability are very important for hydrogen production via water electrolysis with PEM at medium temperature above $80^{\circ}C$. Currently Nafion of Dupont and Aciflex of Asahi, etc., solid polymer electrolytes of perfluorosulfonic acid membrane, are the best performing commercially available polymer electrolytes. However, these membrane have several flaws including its high cost, and its limited operational temperature above $80^{\circ}C$. Because of this, significant research efforts have been devoted to the development of newer and cheaper membranes. In order to make up for the weak points and to improve the mechanical characteristics with cross -linking, acid-base complexes were prepared by the combination PSf-co-PPSS-$NH_2$ with PEEK-$SO_3H$. The results showed that the proton conductivity decreased in 17.6% and 40% but tensile strength increased in 78% and 98%, about $20.65\;{\times}\;10^6N/m^2$, in comparison with SBPSf/HPA and SPEEK/HPA complex membrane.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.673-681
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• 2023

Hydrocarbon-based polymer membranes to replace perfluorinated polymer membranes are being continuously researched. However, hydrocarbon-based membranes have a problem in that they are less durable than fluorine-based membranes. In this study, we sought to compare the annealing effect to improve the durability of sulfonated poly(ether ether ketone) (SPEEK). After membranes formation, thermogravimetric analysis and tensile strength were measured to compare changes in membranes properties due to annealing. After manufacturing the membrane and electrode assembly (MEA), the initial performance and chemical durability was compared with unit cell operation. During the 24-hour annealing process, the strength increased due to the increase in-S-O-S-crosslinking, and the sulfonic acid group decreased, leading to a decrease in I-V performance. By annealing, the hydrogen permeability was reduced to less than 1/10 of that of the nafion membrane, and as a result, open circuit voltage (OCV) and durability was improved. The SPEEK membranes annealed for 24 hours showed higher durability than the nafion 211 membranes of the same thickness.

• 대한기계학회논문집B
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• 제35권5호
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• pp.487-490
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• 2011

본 논문은 동결과 융해가 고분자 전해질 연료전지 내의 기체확산층에 미치는 영향에 대해 X-선 단층 촬영법을 이용하여 수행한 실험적 연구이다. 고분자 전해질 연료전지는 외부 온도가 0 도 이하가 되면 내부의 물이 동결되며, 외부 온도가 0 도 이상으로 상승하면 다시 녹는 과정을 겪게 된다. 이 과정은 연료전지의 내부 구조에 변형을 야기하고 이로 인해 연료전지의 전력과 수명의 감소를 야기하게 된다. 기체확산층은 연료전지 내부에서 가장 두꺼운 다공성층이며, 이로 인해 가장 많은 변형이 발생된다. 본 연구에서는 포항 방사광 가속기의 X-선 단층 촬영법을 이용하여 물의 동결과 융해 과정이 기체확산층의 내부 구조에 미치는 변화를 관찰하였다. 이 기체확산층의 구조 변화가 고분자 전해질 연료전지의 전력 생산과 수명에 미치는 영향에 관해 논의하였다.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.49-56
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• 2020

Epoxy/carbon composite was used to prepare a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Phenol novolac-type epoxy and diglycidyl ether of bisphenol A (DGEBA)-type epoxy mixture was used as a matrix and graphite powder, carbon fiber (CF) and graphite fiber (GF) were used as carbon materials. In order to improve the mechanical properties of the bipolar plate, surface-modified CF was incorporated into the epoxy/carbon composite. To determine the cure temperature of the epoxy mixture, differential scanning calorimetry (DSC) analysis was performed and the data were introduced to Kissinger equation in order to get reaction activation energy and pre-exponential factor. Tensile and flexural strength was obtained by using universal testing machine (UTM). The surface morphology of the fractured specimen and the interfacial morphology between epoxy matrix and CF or GF were observed by a scanning electron microscopy (SEM).

• 신재생에너지
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• 제1권1호
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• pp.72-78
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• 2005

Optimal design and proper operation are important to get aimed output power of a polymer electrolyte membrane fuel cell (PEMFC) stack. An air cooling fuel cell stack is widely used in sub kW PEMFC systems. The purpose of this study is to analyze operating conditions affecting the performance of the air cooling PEMFC which is designed for portable application. In portable applications, air cooling stack is difficult to maintain well balanced operating conditions. The importart parameters are the relative humidity, the temperature of the stack, the utilization of reactant gas and so on. in this study, a 500W air cooling PEMFC was fabricated and tested to evaluate the design performance and to determine optimal operating conditions. Moreover, basic modeling also is carried out. These results can be used 3s design criteria and optimal operating conditions for portable PEMFCs

• 대한기계학회논문집B
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• 제32권11호
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• pp.849-855
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• 2008

The paper addresses modeling and analysis of the part load performance of a hybrid fuel cell system integrating a polymer electrolyte membrane fuel cell(PEMFC) and a gas turbine(GT). The system is a pressurized one where the working pressure of the PEMFC is higher than the ambient pressure. In addition to the two major components, the system also includes auxiliary parts such as a steam reformer, a humidifier, and afterburner and so on. Based on design analysis, component off-design models are incorporated in the analysis program and part load operation is simulated. The mode for the part load operation of the PEMFC/GT hybrid system is a variable rotational speed operation. The operating characteristics and variations in the system efficiency and component performance parameters at part load are analyzed.

• 대한금속재료학회지
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• 제46권12호
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• pp.817-822
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• 2008

Metal matrix composite (MMC) materials having low electrical contact resistance based on 316L stainless steel (STS) matrix alloy with $ZrB_2$ particles were fabricated for PEMFC (Polymer Electrolyte Membrane Fuel Cell) separator by powder metallurgy (PM). The effects of the boride particle addition into the matrix alloy on microstructure, surface morphology, and interfacial contact resistance (ICR) between the samples and gas diffusion layer (GDL) were investigated. Both conventional and PM 316L STS samples showed high ICR due to the existence of non-conductive passive film on the alloy surface. The addition of the boride particles, however, remarkably reduced ICR of the samples. SEM observation revealed that the boride particles were protruded out of the matrix surface and particle density existing on the surface increased with increasing the boride content, causing increase of the total contact area between the conductive particles and GDL. ICR of the samples also decreased with increasing the boride content resulted from the increased contact area.

• Corrosion Science and Technology
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• 제20권6호
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• pp.435-450
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• 2021

The interest in eco-friendly energy is increasing, and polymer electrolyte membrane fuel cell (PEMFC) is attracting attention as alternative power sources. Research on metallic bipolar plates, a fuel cell component, is being actively conducted. However, since the operating conditions of PEMFC, in which sulfuric acid (H₂SO₄) and hydrofluoric acid (HF) are mixed, are strong acidity, the durability of the metallic bipolar plate is very important. In this research, the electrochemical characteristics and corrosion damage behavior of 316L stainless steel, a material for metallic bipolar plates, were analyzed through potentiostatic corrosion tests with test times and chloride concentrations. As the test times and chloride concentrations increased, the current density and corrosion damage increased. As a result of observation with scanning electron microscope(SEM) and 3D microscope, both the depth and width of pitting corrosion increased with increases in test times and chloride concentrations. In particular, the pitting corrosion damage depth at test conditions of 6 hours and 1000 ppm chloride increased the most. The growth of the pitting corrosion damage was not directly proportional to time and increased significantly after a certain period.

• 공업화학전망
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• 제24권3호
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• pp.14-27
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• 2021

수소 에너지는 환경 문제를 최소화하고 고갈되는 화석연료를 대체할 수 있는 에너지원으로 각광을 받고 있다. 수소연료전지는 이러한 수소를 에너지원으로 사용하고 수소를 전기에너지로 전환하여 그 부산물로 물을 만드는 대표적인 친환경 전기화학 장치이다. 고분자 전해질막 연료전지는 수소이온교환 특성을 갖는 고분자막을 전해질로 사용하는 연료전지로 막전극집합체의 전극층은 촉매가 포함된 고분자 전해질막 연료전지의 주요 요소 중의 하나이다. 소재개발 측면에서 고분자 전해질막 연료전지 전극층 핵심 소재의 물성 발현 원리 등을 이해하고 최적화된 소재 설계를 위해서는 원자레벨에서의 소재 설계 접근법이 필요하다. 따라서 실험적인 연구가 어려운 부분과 원자단위에서의 물질 현상에 대한 이해 그리고 연구 개발의 효율성 증진을 위해 전산재료과학(computational materials science) 기술이 광범위하게 활용될 수 있다. 본 기고문에서는 고분자 전해질막 연료전지에서의 전극층 소재에 대한 분자동역학 기반의 전산모사 활용과 연구동향에 대하여 소개하고자 한다.