• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.221-223
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• 2007

고분자전해질연료전지의 효율과 수명은 고분자 전해질 막과 밀접하게 관련되어있다. 연료전지 상용화를 위해 내구성과 안정성은 반드시 확보되어야 한다. 본 연구에서는 고분자전해질연료전지용 막전극접합체에 대해서 제작과정, 체결과정 및 운전 중에 발생할 수 있는 물리적 손상이 연료전지에 미치는 영향을 알아보고자 하였다. 실제 고분자전해질연료전지 조건에서 구멍이 생기는 경우를 모사하기 위해 막전극접합체에 다양한 크기 및 형상의 물리적 손상을 형성시켰다. 또한 여러 위치에서의 손상도 비교하였다. 손상시킨 막전극접합체에 대해 단위전지 성능평가와 순환전압전류 실험을 비교 분석하였다. 막전극접합체의 결함이 커질수록 수소기체투과도는 증가하고, OCV와 성능은 감소하였다. 또한 성능과 수소기체투과도는 서로 관련이 있음을 알 수 있었다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.34-40
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• 1993

전기전자산업에 유기분자집합체에 대한 전자 device적 기능을 갖게 하는 초전막형성 기술의 하나로서 LB막이 이용되게 된다. 10여년전에 만들어 대기중에 방치되었던 Langmuir Blodgett(LB) 초전막 시료에 대해서 MIM구조소자에 전하가 발생하는 특성을 검토하였다.그 결과 LB막이 무극성일 때는 상하부전극을 동일 금속으로 하면 전압이 발생하지 않고, 서로 다른 금속전극으로 할 때는 전압이 발생하였는데 양전극금속의 일함수값의 차가 클수록 발생전압이 높았고 LB막이 유극성일때는 동일 전극이라도 전압이 발생하였다.따라서 LB초전막의 MIM 소자에서 발생하는 전하는 단순한 화학작용에 의한 것이 아니고양전극 금속의 일함수와 극성에 관계가 있다고 생각된다.

• Membrane Journal
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• v.19 no.4
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• pp.291-301
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• 2009

Double-layered polymer electrolyte membranes were prepared from two different sulfonated poly(aryl ether sulfone) copolymers by the two-step solution casting method for direct methanol fuel cells (DMFC). Sulfonation degrees were adjusted 10% (SPAES-10) and 50% (SPAES-50) by controlling monomer ratios, and the weight ratios of SPAES-10 copolymer were varied in the range of 5~20% to investigate the effect of thickness of coating layers on the membranes. Proton conducting layers were fabricated from SPAES-50 solutions of N-methyl-2-pyrrolidone (NMP) by a solution casting technique, and coating layers formed on the semiliquid surface of the conducting layer by pouring of SPAES-10-NMP solutions onto. It was found that double-layered polymer electrolyte membrane could significantly reduce the methanol crossover through the membrane and maintain high proton conductivities being comparable to single-layered SPAES-50 membrane. The maximum power density of membrane-electrolyte assembly (MEA) at the condition of $60^{\circ}C$ and 2 M methanol-air was $134.01\;mW/cm^2$ for the membrane prepared in the 5 wt-% of SPAES-10 copolymer, and it was corresponding to the 105.5% of the performance of the commercial Nafion 115 membrane.

• Polymer(Korea)
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• v.31 no.3
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• pp.255-262
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• 2007

In this work, two types of copolymers are manufactured by a radical polymerization to develop a material for humid membrane. Each copolymer contains three monomers that have functions to improve humid-resistance, membrane stability, flexibility, impedance, and adhesion to the electrode. MDBAB (N,N'-dimethyl-2-methacryloxyethyl-3-bromopropyl ammonium bromide) having a salt form decreases the impedance of the humid membrane and reacts with amines to produce a cross-linking structure. HEMA (2-hydroxyethyl methacrylate) has an important role which reduces the impedance and increases the adhesion strength to the electrode. The other monomers are DAEMA (N,N'-dimethylamino ethyl methacrylate), 4-VP(4-vinyl pyridine), and 2-EHA(2-ethylhexyl acrylate) and all the monomers are formulated with several compositions to make a humid membrane. At specific composition, we could attain a satisfactory results having good performance and long term durability.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.21-27
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• 2003

The copolymers with various composition of methyl methacrylate (MMA), ethyl methacrylate (EMA), methacrylic acid (MA) and hydroxyethyl methacrylate (HEMA) were synthesized for capacitive humidity sensitive materials. The capacitive humidity sensor consisted of a polymethacrylate film coated on both sides with gold electrode. Capacitance versus relative humidity increased with HEMA content in the copolymer. In the case of self-crosslinkable MMA/MA/HEHA= 40/10/10, the average capacitance at 30%RH, 60%RH and 90%RH are 102, 134 and 166 pF, respectively. And also, the hysteresis, temperature cycle and long-term stability were evaluated as a capacitance humidity sensor.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.129-132
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• 2007

고분자 전해질 연료전지의 성능에 영향을 주는 많은 인자들 중에서도 촉매층의 조성과 구조의 최적화는 성능변화에 큰 요인으로 작용 된다. 촉매층내 반응 활성점인 삼상계면을 형성시키기 위해 함침하는 Nafion binder를 anode와 cathode의 두 전극에 이온당량(Equivalent weight, EW)이 동일하게 함침시켜 그 성능을 확인하였다. 그 결과를 토대로 anode와 cathode에 이온당량을 각기 다르게 하여 각각의 전극마다 이온당량이 미치는 영향에 대해서도 살펴보았다. Anode와 cathode의 이온당량을 동일하게 EW1100, EW1000, EW900으로 변화 시켜주었을 경우 이온당량의 물성치가 상대적으로 향상된 EW900의 단위 전지 성능이 가장 우수하였으며, 이온당량이 EW900이었을 때 최적의 Nafion binder 함침량은 EW1100의 Nafion binder 함침량과 동일하였다. Anode와 cathode에 함침하는 Nafion binder의 이온당량을 각각 EW1100과 EW900, EW900과 EW1100으로 MEA를 제조하여 전극에 따라 이용당량이 미치는 영향을 살펴보았다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.230-234
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• 2005

Fabrication of MEA is important factor for proton exchange membrane fuel cell (PEMFC). MEA of PEMFC with hot pressing and direct coating method were prepared, and performances were evaluated and compared each other. The effect of MEA preparation methods, hot pressing methods and direct coating methods, on the cell performance was analyzed by impedance spectroscopy and SEM. The performance of PEMFC with direct coating method was better than with hot pressing method because membrane internal resistance and membrane-interfacial resistance were reduced by elimination of hot pressing process in MEA fabrication. In addition the micro structure of MEA with direct coating method reveals uniform interface between membrane and catalyst layer.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.825-830
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• 2000

The copolymers with various composition of vinylbenzyl chloride (VBC), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate(HEMA) were synthesized as a humidity sensitive material and quaternized with N, N, N', N'-tetraethylene diamine.. Resistance versus relative humidity decreased with increase in the content of MMA in the copolymer. The introduction of HPMA increased the resistance of the humidity sensor as well as enhanced the adherence to the alumina substrate. In the case of VBC/MMA/HEMA=80/10/10, the hysteresis and temperature dependency coefficient were $\pm$2%RH and -0.46~0.42%RH/$^{\circ}C$. The average resistance at 30%RH, 60%RH and 90%RH were 3.0M$\Omega$ ,200k$\Omega$ and 9k$\Omega$, respectively.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.305-309
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• 2016

Recently, there are many efforts focused on development of more economical non-fluorinated membranes for PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, to test the durability of sPEEK MEA (Membrane and Electrode Assembly), ADT (Accelerated Degradation Test) of MEA degradation was done at the condition that membrane and electrode were degraded simultaneously. Before and after degradation, I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. Although the permeability of hydrogen through sPEEK membrane was low, sPEEK membrane was weaker to radical evolved at low humidity and OCV condition than fluorinated membrane such as Nafion. Performance after MEA degradation for 144 hours and 271 hours were reduced by 15% and 65%, respectively. It was showed that the main cause of rapid decrease of performance after 144 hours was shorting due to Pt/C particles in the pinholes.

• Journal of the Korean Electrochemical Society
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• v.11 no.2
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• pp.125-129
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• 2008

Rechargeable lithium-ion polymer batteries have been considered to be next-generation power sources for portable electronic devices and electric vehicles. In this work, we tried to improve the cycling performances of lithium-ion polymer cells by coating aluminum fluoride and acrylonitrile-methyl methacrylate copolymer to the polyethylene separator. It was found that the addition of aluminum fluoride to the surface-modified separator reduced the interfacial resistances and thus the cell exhibited a less capacity fading and better high rate performance. The cell showed an initial discharge capacity of 150 mAh/g and good capacity retention at 0.5 C rate.