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동결/해동 조건에서 기체확산층의 물성이 고분자전해질연료전지의 내구성에 미치는 영향
박구곤(Park, Gu-Gon),임수진(Lim, Soo-Jin),박진수(Park, Jin-Soo),손영준(Sohn, Young-Jun),임성대(Yim, Sung-Dae),김창수(Kim, Chang-Soo),양태현(Yang, Tae-Hyun) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
The effect of the kind of gas diffusion layers (GDLs) on the freeze/thaw condition durability in polymer electrolyte fuel cells (PEFCs) were investigated. For this purpose, three kinds of GDLs, i.e., felt, paper and cloth types with different basic properties have been first prepared, then the changes in the properties and performance of cells was observed during the freeze/thaw cycles ranging from -30 to 70 ?C. The single cells consisting of different GDLs were evaluated for performance. The performance degradation and the cell resistance increase could be directly correlated. The physical destruction of electrode was shown by SEM analysis. It was presented that mechanical supporting force of interface between materials can help enhancing the durability of PEFCs in the freeze/thaw condition.
고분자전해질 연료전지 체결조건에서 기체확산층의 특성변화 및 물거동 확인
박구곤(Park, Gu-Gon),임남윤(Lim, Nam-Yun),안은진(Ahn, Eun-Jin),박진수(Park, Jin-Soo),윤영기(Yoon, Young-Gi),이원용(Lee, Won-Yong),임태원(Lim, Tae-Won),김창수(Kim, Chan-Soo) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.11
Proper water management is important to achieve high performance and durability of Polymer electrolyte fuel cell (PEFC). Among various stack components, gas diffusion layer (GDL) is considered as a core part to determine the gas and water transportation in a cell. To optimize the water management, the changes of properties as well as basic properties of GDLs were investigated before and after clamping of colls. Thickness, electric conductivity, porosity, hydroppobicity etc. were characterized by the same criteria. The amount of residual water after cell operation also was compared by direct measuring of weight. Based on the amount of residual water the endurance on the freeze condition was evaluated.
박구곤(Park, Gu-Gon),임남윤(Lim, Nam-Yun),손영준(Sohn, Young-Jun),박진수(Park, Jin-Soo),이원용(Lee, Won-Yong),김세훈(Kim, Sae-Hoon),임태원(Lim, Tae-Won),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
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?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?C) cycle.
체결압이 고분자연료전지 기체확산층의 표면성질에 미치는 영향
안은진,박구곤,윤영기,박진수,이원용,김창수,Ahn, Eun-Jin,Park, Gu-Gon,Yoon, Young-Gi,Park, Jin-Soo,Lee, Won-Yong,Kim, Chang-Soo 한국전기화학회 2007 한국전기화학회지 Vol.10 No.4
고분자연료전지에 사용되는 다공성 매체인 기체확산층은 그 특성에 따라 원활한 기체의 확산과 물 배출을 결정지으며 그 결과 연료전지 성능과 내구성에까지 영향을 미친다. 최적의 물관리와 기체확산층 내에서의 이상(two phase) 유동이해를 위해서는 실제 체결 조건에서의 기체확산층의 성질을 아는 것이 중요하다. 이에 대해 물리적, 전기화학적, 기계적 성질을 알기 위한 실험 등이 수행되어져 왔다. 하지만 실제 스택의 체결 조건에서 기체확산층의 표면 화학적 변화에 대한 실험은 그다지 알려져 있지 않다. 본 연구에서는 단순한 체결 과정만으로도 기체확산층에 대한 물리화학적인 변화를 야기할 수 있음을 확인하였으며, 기체확산층을 구성하는 탄소 섬유 및 PTFE의 손상과 변형을 전자주사현미경으로 직접 관찰할 수 있었다. 관찰된 물리적 손상이 표면의 소수성 변화에 미치는 영향을 알아보기 위해 표면 원소성분 분석과 농도가 다른 에탄올 수용액 흡수량 측정을 수행하였다. 그 결과 체결압에 의해서 분리판의 rib 전단 및 아래에서 심한 파손이 일어나며, 탄소 섬유의 끊어짐 및 섬유 사이에 존재하는 탄소 파우더 역시 심하게 눌린 현상을 관찰할 수 있었다. 체결과정을 경험한 기체확산층에 대한 liquid uptake양을 확인한 결과, 표면 PTFE 함량의 상대적 감소가 기체확산층의 표면을 소수성에서 친수성으로 변화시켰음을 직접적으로 확인하였다. Characteristics of GDL (Gas Diffusion Layer) mainly determine the gas diffusion and water removal in a cell, thereby changing the performance and affecting durability of PEFC. To optimize the water management and understand the two phase flow in a GDL, it is important to study the behaviors of GDL micro structure under the real operating condition. In the clamped condition of cell, the GDL beneath the rib is more compressed than beneath the channel. Many researches on physical, electrochemical, mechanical behaviors of gas diffusion layer has been conducted. However, changes in surface properties under clamped condition have rarely studied. In present study, the morphology of broken connections of carbon fibers and detachment of PTFE coatings on the fibers were shown from the microscopic observations. In addition, changes in wetting properties of GDL by compression were investigated by using XPS and liquid uptake methods. The hydrophobic characteristics of GDL surface beneath the rib of the flow field plate are changed due to the deformation of micro structure.
박진수(Park, Jin-Soo),백지숙(Baek, Ji-Suk),양태현(Yang, Tae-Hyun),김창수(Kim, Chang-Soo),임성대(Yim, Sung-Dae),박구곤(Park, Gu-Gon) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
This study presents preparation and characterization of composite membranes based on ionic liquids. The ionic liquids act as water in sulfonated membranes. On the behalf of ionic conduction through ionic liquid inside the membranes, non-aqueous membranes showed Arrenhius dependence on temperature with no external humidification. It was implied that hopping mechanism of proton was dominant in the ionic liquid based membranes. In addition, small angle X-ray (SAXS) studies provided the information on morphology of ionic clusters formed by the interaction between sulfonic acid groups of the polymers and ionic liquids. The SAXS spectra showed matrix peaks, ionomer peaks and Prodo's law for Nafion based composite membranes and only matrix peaks for hydrocarbon based ones. However, ionic conductivity and atomic force microscopy (AFM) images showed the clear formation of ionic clusters of the hydrocarbon based composite membranes. It implies for ionic liquid based high temperature membranes that it is important to use sulfonated polymers as solid matrix of ionic liquid which can form clear ionic clusters in SAXS spectra.
Visualization of water management in a PEFC using a synchrotron
김승곤(Seung-Gon Kim),박구곤(Gu-Gon park),김창수(Chang-Soo Kim),이상준(Sang-Joon Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Water management in a polymer electrolyte fuel cell (PEFC) is vital to enhance performance and durability. In this study, transport of water inside MEA (membrane electrode assembly) and GDL (gas diffusion layer) layers of an operating (in situ) fuel cell was observed using the synchrotron X-ray micro-imaging technique. The synchrotron X-ray imaging technique having high spatial and temporal resolutions was found to be suitable for observing the dynamic behavior of liquid layer and water distribution inside the PEFC. A single-cell test kit of PEFC was specially designed for this X-ray imaging experiments. Temporal variation of gray level in the PEFC components, such as MEA, GDL and endplate was investigated with varying loading condition. As a result, the PEFC components were clearly distinguished by image pattern and gray level difference in the X-ray images captured. The gray level distribution is roughly symmetric with respect to MEA layer. The gray level at GDL decreases with lapse of time, indicating the increase of H₂O concentration with time.
동결/해동 열사이클이 PEFC의 GDL/MEA에 미치는 영향
임남윤(Lim, Nam-Yun),박구곤(Park, Gu-Gon),박진수(Park, Jin-Soo),윤영기(Yoon, Young-Gi),이원용(Lee, Won-Yong),임태원(Lim, Tae-Won),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.06
Proper water management is vital to achieve high performance and durability of PEFC (Polymer Electrolyte Fuel Cell). The effects of the residual water from PEFC after purge in shut-down processes on GDL/MEAs were investigated with freeze/thaw cycles Freeze/thaw cycle tests were conducted with single cells which were designed from transparent acryl plates. Single cells which contain several amount of residual water were cycles from 80?C to -28?C. The resistance changes of the single cells which have various amount of residual water were evaluated by ac-impedance analysis with 24 times of freeze/thaw cycles. Also, after the freeze/thaw cycles, the property changes were characterized by visual methods such as SEM, EPMA. Though it was difficult to observe noticeable property changes in the visual characterizations, the resistance of cells dramatically increased with the amount of remained water.
Bimodal 다공성 탄소지지체에 담지된 고분자전해질연료전지용 전극촉매 제조
황소희(Hwang, So-hee),박구곤(Park, Gu-Gon),임성대(Yim, Sung-Dae),박석희(Park, Seok-Hee),김한성(Kim, Han-Sung),양태현(Yang, Tae-Hyun),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
The bimodal porous carbons were synthesized by using imprinting method with templates of SBA-15 particle and silica sphere and applied as supporting materials for the electro-catalyst of polymer electrolyte fuel cell (PEFC). The silica spheres with diameter size of 100 nm and SBA-15 particle having 200 nm -250 nm diameter and 700 nm -900 nm length were synthesized in this work. The bimodal porous carbons (S100) were prepared by using the silica spheres and SBA-15 as templates and mesophase pitch as a carbon source. The PtRu nanoparticle of ca. 1.9 nm were supported on the bimodal porous carbon support and the resulting PtRu/S100 catalysts was tested by the cyclic voltammetry. The use of bimodal porous carbon showed in comparable electro-catalytic activities with commercial catalyst. Though unclear effects of bimodal porosity of supports could be obtained in the scope of this study, morphological advantage in electrical conductivity can be considered on the electro-catalytic activity.
임수진(Lim, Soo-Jin),박구곤(Park, Gu-Gon),박진수(Park, Jin-Soo),박석희(Park, Seok-Hee),윤영기(Yoon, Young-Gi),이원용(Lee, Won-Yong),임태원(Lim, Tae-Won),이영무(Lee, Young-Moo),김창수(Kim, Chang-Soo) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.06
고분자전해질연료전지 시스템이 영하 조건에 노출될 경우, 셀의 성능 및 내구성에 미치는 영향을 실험적으로 확인해 보았다. -30 ?C{sim}70 ?C 조건을 반복 경험시키며, 성능저하 정도를 살펴보았다. 일반적인 운전조건과 동결/해동에 의한 성능저하 요인을 분리하여 확인하기 위해, 30 ?C{sim}70 ?C 범위의 사이클을 진행한 경우에 대해, 위와 통일한 분석을 통하여 성능 및 각종 물성 값의 변화를 비교하였다. 동결조건에서 셀의 성능저하는 형성된 얼음의 물리적 부피팽창으로 인한 계면저항의 증가가 주요 원인임을 밝힐 수 있었다.