• Title, Summary, Keyword: Polymer electrolyte membrane

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Synthesis and Characterization of Polybenzimidazoles Containing Perfluorocyclobutane Groups for High-temperature Fuel Cell Applications

  • Chang, Bong-Jun;Kim, Dong-Jin;Kim, Jeong-Hoon;Lee, Soo-Bok;Joo, Hyeok-Jong
    • Korean Membrane Journal
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    • v.9 no.1
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    • pp.43-51
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    • 2007
  • This paper describes the preparation and characterization of two kinds of fluorinated polybenzimidazole (PBI)s which can be potentially used for phosphoric acid-doped, high-temperature polymer electrolyte membrane fuel cells. Two kinds of perfluorocyclobutane (PFCB)-containing monomers were prepared via following synthetic steps; after fluoroalkylation of methyl 3-(hydroxy) benzoate and methyl 4-(hydroxy) benzoate with 1,2-dibromotetrafluoroethane and subsequent Zn-mediated dehalogenation, these compounds were cyclodimerized at $200^{\circ}C$ affording the ester-terminated monomers containing PFCB ether groups. The synthesized intermediates and monomers were characterized using FT-IR, $^1H-NMR,\;^{19}F-NMR$, and mass spectroscopy. The fluorinated PBIs were then successfully prepared through the solution polycondensation of the monomers and 3,3'-diaminobenzidine in polyphosphoric acid. Compared with traditional PBI, the glass transition temperatures of the fluorinated PBIs were obtained at $262^{\circ}C\;and\;269^{\circ}C$ which are lower than that of PBI and their initial degradation temperatures were still high over $400^{\circ}C$ under nitrogen. The fluorinated PBIs showed higher d-spacing values and improved solubility in several organic solvents as well as phosphoric acid, which confirmed they could be good candidates for the high temperature fuel cell membranes.

Nafion Composite Membranes Containing Rod-Shaped Polyrotaxanes for Direct Methanol Fuel Cells

  • Cho Hyun-Dong;Won Jong-Ok;Ha Heung-Yong;Kang Yong-Soo
    • Macromolecular Research
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    • v.14 no.2
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    • pp.214-219
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    • 2006
  • Cast Nafion-based composite membranes containing different amounts of organic, nanorod-shaped polyrotaxane were prepared and characterized, with the aim of improving the properties of polymer electrolyte membranes for direct methanol fuel cell applications. Polyrotaxane was prepared using the inclusion-complex reaction between ${\alpha}$-cyclodextrin and poly(ethylene glycol) (PEG) of different molecular weights. The addition of polyrotaxane to Nafion changed the morphology and reduced the crystallinity. The conductivity of the composite membranes increased with increasing polyrotaxane content up to 5 wt%, but then decreased at higher polyrotaxane contents. Well-dispersed, organic polyrotaxane inside the membrane can provide a tortuous path for the transport of methanol, as the methanol permeability depends on the aspect ratio of polyrotaxane, which is controlled by the molecular weight of PEG. All of the Nafion-based, polyrotaxane composite membranes showed a higher selectivity parameter than the commercial Nafion films did.

Preparation and application of gel type polymer electrolyte for PEFC (PEFC 연료전지용 겔 타입 고분자 전해질 합성 및 응용)

  • Lee, Sang-Yong;You, Ji-Yeon;Kim, Han-Joo;Oh, Mee-Hye;Park, Soo-Gil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.42-45
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    • 2003
  • Inorganic polymer based hybrid membranes consisting of zirconium oxide and polydimethylsiloxane (PDMS) have been synthesized by sol-gel processes. The hybrid membranes showed thermal stability and flexibility up to $300^{\circ}C$. The membrane becomes proton conducting polymer electrolyte when added with 12-phosphotungstic acid (PWA). The conductivity of the membranes was measured in the temperature range from room temperature to $150^{\circ}C$ under saturated humidity and a maximum conductivity of $5{\times}10^{-5}\;Sm^{-1}$ was obtained at $150^{\circ}C$.

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Recent Advances in Polybenzimidazole (PBI)-based Polymer Electrolyte Membranes for High Temperature Fuel Cell Applications

  • Vijayakumar, Vijayalekshmi;Kim, Kihyun;Nam, Sang Yong
    • Applied Chemistry for Engineering
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    • v.30 no.6
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    • pp.643-651
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    • 2019
  • Polybenzimidazole (PBI), an engineering polymer with well-known excellent thermal, chemical and mechanical stabilities has been recognized as an alternative to high temperature polymer electrolyte membranes (HT-PEMs). This review focuses on recent advances made on the development of PBI-based HT-PEMs for fuel cell applications. PBI-based membranes discussed were prepared by various strategies such as structural modification, cross-linking, blending and organic-inorganic composites. In addition, intriguing properties of the PBI-based membranes as well as their fuel cell performances were highligted.

Pore-filling anion conducting membranes and their cell performance for a solid alkaline fuel cell (세공충진 음이온 전도성막의 제조 및 이를 이용한 고체알칼리 연료전지 성능 평가)

  • Choi, Youngwoo;Lee, Misoon;Park, Gugon;Yim, Sungdae;Yang, Taehyun;Kim, Changsoo
    • 한국신재생에너지학회:학술대회논문집
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    • pp.129.2-129.2
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    • 2010
  • AEM which were used for solid alkaline fuel cell(SAFC) were prepared by photo polymerization in method pore-filling with various quaternary ammonium cationic monomers and crosslinkers without an amination process. Their specific thermal and chemical properties were characterized through various analyses and the physico-chemical properties of the prepared electrolyte membranes such as swelling behavior, ion exchange capacity and ionic conductivity were also investigated in correlation with the electrolyte composition. The polymer electrolyte membranes prepared in this study have a very wide hydroxyl ion conductivity range of 0.01 - 0.45S/cm depending on the composition ratio of the electrolyte monomer and crosslinking agent used for polymerization. However, the hydroxyl ion conductivity of the membranes was relatively higher at the whole cases than those of commercial products such as A201 membrane of Tokuyama. These pore-filling membranes have also excellent properties such as smaller dimensional affects when swollen in solvents, higher mechanical strength, lowest electrolyte crossover through the membranes, and easier preparation process compared of traditional cast membranes. The prepared membranes were then applied to solid alkaline fuel cell and it was found comparable fuel cell performance to A201 membrane of Tokuyama.

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Study for the Deformation and Fatigue Life of a PEMFC (고분자 전해질 연료전지 막의 변형 및 피로수명)

  • Yang, Jeong-Hwan;Park, Jung-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.5
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    • pp.400-407
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    • 2011
  • The stress distribution and stress amplitude of a membrane are major factors to decide the mechanical fatigue life of PEMFC (Polymer Electrolyte Membrane Fuel Cell). In this paper, mechanical stresses under operating hygro-thermal condition of the membrane are numerically modelled. Contact analysis between gas diffusion layer (GDL) and the membrane is performed under various temperature-humidity conditions. The structural model has nonlinear material properties depending on temperature and relative humidity. Several geometric conditions are applied to the model. The numerical analysis results indicate that deformations of the membrane are strongly related with assembly conditions of the fuel cell. The fatigue life is predicted for practical operating condition through experimental data.

Developement of a PEFC electrodes under the high temperature and low humidified conditions (고온/저 가습 운전을 위한 고분자 전해질 연료전지용 전극 개발)

  • Ryu, Sung-Kwan;Choi, Young-Woo;Park, Jin-Soo;Yim, Sung-Dae;Yang, Tae-Hyun;Kim, Han-Sung;Kim, Chang-Soo
    • 한국신재생에너지학회:학술대회논문집
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    • pp.149-149
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    • 2009
  • Generally, Nafion ionomer is used in the polymer electrolyte fuel cell (PEFC) electrodes to achieve high power density. At the high temperature operation of PEFC, however, ionic conductivity of Nafion remarkably decreased due to the evaporation of water in Nafion polymer. Recently, many researchers have focused on using the Ionic Liquids(ILs) instead of water in Nafion polymer. ILs have intrinsic properties such as good electrochemical stability, high ionic conductivity, and non-flammability. Especially, ILs play a crucial role in proton conduction by the Grottuss mechanism and act as water in water-free Nafion polymer. However, it was found that the ILs was leached out of the polymer matrix easily. In this study, we prepared membrane electrode assemblies with various contents of ILs. The effect of ILs in the electrode of each designed was investigated by a cyclic voltammetry measurement and the cell performance obtained through a single cell test using H2/Air gases. Electrodes with different contents of ILs in catalyst layer were examined at high temperature and low humidified condition.

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Studies on Physical Properties of Sulfonpolyimide for Fuel Cell (연료전지용 술폰폴리이미드의 물성 연구)

  • Ko, Jae-Churl;Ahn, Bum-Jong;Park, Young-Goo
    • Journal of the Korean Applied Science and Technology
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    • v.22 no.2
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    • pp.151-156
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    • 2005
  • Many researchers have been focused on polymer electrolyte membrane (PEM) to improve performance of a fuel cell. Sulfonpolyimide with hydrocarbon was synthesized from ODA (4,4-diaminodiphenyl ether), ODADS (4,4-diaminodiphenyl ether-2,2-disulfonic acid), NTDA (1,4,5,8-naphthalenetetracarboxylicdianhydride) and CSA (chlorosulfonic acid). In order to estimate the feasibility as a fuel cell, the performance of sulfonpolyimide was analyzed through a swelling degree, IEC (ion exchange capacity), ion conductivity and TEM (transmission electron microscope). As the results of this performance test, swelling degree, IEC and ion conductivity were 37%, 0.06 meq/g and 0.08 S/cm respectively, when the CSA concentration was 0.4 M. It was thought that sulfonpolyimide could be used as a fuel cell through improvement of electrolyte membrane.

Development and Evaluation of Gasket for Polymer Electrolyte Membrane Fuel Cell Stacks (고분자 전해질 연료전지 가스켓 설계 및 성능 평가)

  • Seo, Hakyu;Han, In-Su;Jung, Jeehoon;Kim, Minsung;Shin, Hyungil;Hur, Taeuk;Cho, Sungbaek
    • 한국신재생에너지학회:학술대회논문집
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    • pp.90.1-90.1
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    • 2010
  • The design and fabrication of a metallic bipolar plate-gasket assembly for polymer electrolyte fuel cells (PEMFCs) is defined. This bipolar plate-gasket assembly was prepared by inserting a previously prepared bipolar plate in the specially designed gasket mold. For this aim, a proprietary fluoro-silicone based rubber was injected directly into the bipolar plate borders. Gaskets obtained like this showed the chemically / physically stable and the good sealibilty in typically operating PEM fuel cell conditions. And also, this bipolar plate-gasket assembly shows lots of advantages with respect to traditional PEMFCs stack assembling systems: useful application to automative stacking due to easy handling, reduced fabrication time, possibility of quality control and failed elements substitution. This bipolar plate-gasket assembly was evaluated in the short fuel cell stack and met the leakage requirement for normal operation both in short-term and in long-term operation. Especially, it was confirmed that this gasket could be applied successfully even in the high pressure FEM fuel cell systems(over 2.0 bar in absolute pressure).

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The Analysis on the Activation Procedure of Polymer Electrolyte Fuel Cells

  • Jang, Jong-Mun;Park, Gu-Gon;Sohn, Young-Jun;Yim, Sung-Dae;Kim, Chang-Soo;Yang, Tae-Hyun
    • Journal of Electrochemical Science and Technology
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    • v.2 no.3
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    • pp.131-135
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    • 2011
  • It is, in general, believed that during the activation process, the proton conductivity increases due to wetting effect and the electrochemical resistance reduction, resulting in an increase in the fuel cell performance with time. However, until now, very scant information is available on the understanding of activation processes. In this study, dominant variables that effect on the performance increase of membrane electrode assemblies (MEAs) during the activation process were investigated. Wetting, pore restructuring and active metal utilization were analyzed systematically. Unexpectedly, the changes for both ohmic and reaction resistance characterized by the electrochemical impedance spectroscopy (EIS) after initial wetting process were much smaller when considering the degree of cell performance increases. However, the EIS spectra represents that the pore opening of electrode turns into gas transportable structure more easily. The increase in the performance with activation cycles was also investigated in a view of active metals. Though the particle size was grown, the number of effective active sites might be exposed more. The impurity removal and catalytic activity enhancement measured by cyclic voltammetry (CV) could be a strong evident. The results and analysis revealed that, not merely wetting of membrane but also restructuring of electrodeand catalytic activity increase are important factors for the fast and efficient activation of the polymer electrolyte fuel cells.