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Influence of water behavior in the gas diffusing layer one the performance of PEMFC
박구곤,손영준,임성대,양태현,윤영기,이원용,김창수 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.1
Experimentally, the affect of water behavior on the performance of polymer electrolyte membrane fuel cell(PEMFC) was investigated. To understand the water transportation phenomena systematically, the gas diffusion layers were divided to two parts. One is gas diffusion medium(GDM) and the other is micro-layer(ML). In this work, GDM with different PTFE contents was intensively investigated at various single cell operation conditions. I-V performance curves of single cells were compared and analyzed with respect to water transportation in the GDM. By this work, the dominant driving forces of the water transportation in the gas diffusion layer were suggested for the design of gas diffusion layers.
Analysis on the freeze/thaw cycled polymer electrolyte fuel cells
박구곤,Soo-Jin Lim,박진수,임성대,박석희,양태현,윤영기,김창수 한국물리학회 2010 Current Applied Physics Vol.10 No.2
Enhancement of system durability at the sub-freezing temperature is one of critical issues for the commercialization of polymer electrolyte fuel cell (PEFC) applications. In this work, effects of residual water at the sub-freeze condition on the gas diffusion layer (GDL)/membrane-electrode assembly (MEA) were investigated for the successful cold start-up of PEFC. The performance changes of MEAs were observed by 300 times of freeze/thaw (F/T) cycles with well designed single cell. The post analysis for the (-30 to 70) ℃ F/T cycled MEA were conducted. The gradual decreases of I–V performance were observed after the F/T cycle number of 70. About 0.4 mV/cycle of degradation at 1 A/㎠ could be obtained at the controlled operating conditions. The main cause of performance decrease was in the weakened adhesion between the electrodes and membrane interface. The SEM images as well as cell resistance changes directly supported the degradation reasons of cell performance in the freeze condition.
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.
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.
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.