• Title, Summary, Keyword: Polymer electrolyte membrane

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Characterization of DNA/Poly(ethylene imine) Electrolyte Membranes

  • Park, Jin-Kyoung;Won, Jong-Ok;Kim, Chan-Kyung
    • Macromolecular Research
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    • v.15 no.6
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    • pp.581-586
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    • 2007
  • Cast DNA/polyethyleneimine (PEI) blend membranes containing different amounts of DNA were prepared using acid-base interaction and characterized with the aim of understanding the polymer electrolyte membrane properties. Two different molecular weights of PEI were used to provide the mechanical strength, while DNA, a polyelectrolyte, was used for the proton transport channel. Proton conductivity was observed for the DNA/PEI membrane and reached approximately $3.0{\times}10^{-3}S/cm$ for a DNA loading of 16 wt% at $80^{\circ}C$. The proton transport phenomena of the DNA/PEI complexes were investigated in terms of the complexation energy using the density functional theory method. In the case of DNA/PEI, a cisoid-type complex was more favorable for both the formation of the complex and the dissociation of hydrogen from the phosphate. Since the main requirement for proton transport in the polymer matrix is to dissociate the hydrogen from its ionic sites, this suggests the significant role played by the basicity of the matrix.

Polymer Electrolyte Membranes and their Applications to Membranes, Fuel Cells and Solar Cells

  • Kang, Yong-Soo
    • Proceedings of the Membrane Society of Korea Conference
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    • pp.29-32
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    • 2003
  • Polymer electrolyte membranes are developed for the applications to facilitated transport membranes, fuel cells and solar cells. The polymer electrolyte membranes containing silver salt show the remarkably high separation performance for olefin/paraffin mixture in the solid state; the propylene permeance is 45 GPU and the ideal selectivity of propylene/propane is 15,000. For fuel cell membranes, the effects of the presence and size of the proton transport channels on the proton conductivity and methanol permeability were investigated. The cell performance for dye-sensitized solar cells employing polymer electrolytes are measured under light illumination. The overall energy conversion efficiency reaches 5.44 % at 10 ㎽/$\textrm{cm}^2$, to our knowledge the highest value ever reported in the polymer electrolytes.

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Decrease in hydrogen crossover through membrane of polymer electrolyte membrane fuel cells at the initial stages of an acceleration stress test

  • Hwang, Byung Chan;Oh, So Hyeong;Lee, Moo Seok;Lee, Dong Hoon;Park, Kwon Pil
    • Korean Journal of Chemical Engineering
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    • v.35 no.11
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    • pp.2290-2295
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    • 2018
  • An acceleration stress test (AST) was performed to evaluate the durability of a polymer membrane in a polymer electrolyte membrane fuel cell (PEMFC) for 500 hours. Previous studies have shown that hydrogen crossover measured by linear sweep voltammetry (LSV) increases when the polymer membrane deteriorates in the AST process. On the other hand, hydrogen crossover of the membrane often decreases in the early stages of the AST test. To investigate the cause of this phenomenon, we analyzed the MEA operated for 50 hours using the AST method (OCV, RH 30% and $90^{\circ}C$). Cyclic voltammetry and transmission electron showed that the electrochemical surface area (ECSA) decreased due to the growth of electrode catalyst particles and that the hydrogen crossover current density measured by LSV could be reduced. Fourier transform infrared spectroscopy and thermogravimetric/differential thermal analysis showed that -S-O-S- crosslinking occurred in the polymer after the 50 hour AST. Gas chromatography showed that the hydrogen permeability was decreased by -S-O-S- crosslinking. The reduction of the hydrogen crossover current density measured by LSV in the early stages of AST could be caused by both reduction of the electrochemical surface area of the electrode catalyst and -S-O-S- crosslinking.

TA Study on the Performance and the Efficiency in Polymer Electrolyte embrane Fuel Cell (고분자전해질형 연료전지의 성능해석 및 효율에 관한 연구)

  • Kim Hong-Gun;Kim Yoo-Shin;Yang Sung-Mo;Nah Seok-Chan
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.4
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    • pp.75-80
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    • 2005
  • An experimental study is carried out to investigate the performance and the efficiency humidifying Membrane Electrolyte Assembly and having the double-tied catalyst layers in a fuel cell system which is taken into account the physical and thermal concept. Subsequently, an electric output produced by PEMFC(Polymer Electrolyte Membrane Fuel Cell) is measured to assess the performance of a stack, and the efficiency is also evaluated according to the different situation in which unit cell is placed with and without the humidification of the MEA. It is found that the measured values of stack voltage and current are influenced by the stack temperature, humidification, and the double-tied catalyst layers which give more enhanced values to be applied to electric units.

Improving Power Conversion Efficiency and Long-term Stability Using a Multifunctional Network Polymer Membrane Electrolyte; A Novel Quasi-solid State Dye-sensitized Solar Cell

  • Gang, Gyeong-Ho;Gwon, Yeong-Su;Song, In-Yeong;Park, Seong-Hae;Park, Tae-Ho
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.484.2-484.2
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    • 2014
  • There are many efforts to improving the power conversion efficiencies (PCEs) of dye-sensitized solar cells (DSCs). Although DSCs have a low production cost, their low PCE and low thermal stability have limited commercial applications. This study describes the preparation of a novel multifunctional polymer gel electrolyte in which a cross-linking polymerization reaction is used to encapsulate $TiO_2$ nanoparticles toward improving the power conversion efficiency and long-term stability of a quasi-solid state DSC. A series of liquid junction dye-sensitized solar cells (DSCs) was fabricated based on polymer membrane encapsulated dye-sensitized $TiO_2$ nanoparticles, prepared using a surface-induced cross-linking polymerization reaction, to investigate the dependence of the solar cell performance on the encapsulating membrane layer thickness. The ion conductivity decreased as the membrane thickness increased; however, the long term-stability of the devices improved with increasing membrane thickness. Nanoparticles encapsulated in a thick membrane (ca. 37 nm), obtained using a 90 min polymerization time, exhibited excellent pore filling among $TiO_2$ particles. This nanoparticle layer was used to fabricate a thin-layered, quasi-solid state DSC. The thick membrane prevented short-circuit paths from forming between the counter and the $TiO_2$ electrode, thereby reducing the minimum necessary electrode separation distance. The quasi-solid state DSC yielded a high power conversion efficiency (7.6/8.1%) and excellent stability during heating at $65^{\circ}C$ over 30 days. These performance characteristics were superior to those obtained from a conventional DSC (7.5/3.5%) prepared using a $TiO_2$ active layer with the same thickness. The reduced electrode separation distance shortened the charge transport pathways, which compensated for the reduced ion conductivity in the polymer gel electrolyte. Excellent pore filling on the $TiO_2$ particles minimized the exposure of the dye to the liquid and reduced dye detachment.

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A Study on the Ion Permeability Characteristics in Nano-Polymer Membrane Structures (나노고분자막 구조의 이온투과 특성에 관한 연구)

  • Kim, Yoo-Young
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.133-137
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    • 2006
  • Ion permeability characteristics in nano-polymer membrane structures are performed to investigate the chemical composition and characteristics of MEA(Membrane Electrolyte Assembly) which is one of the most important parts to decide the performance in PEMFC(Polymer Electrolyte Membrane Fuel Cell) system. Subsequently, the MEA manufacturing process is presented for the uniformed MEA product. In the meantime, the analysis of SEM(Scanning Electron Microscope) is carried out in order to investigate the joint aspect and chemical composition of MEA. As a result of SEM analysis, it is found that the bonded catalyst and carbon composition contain the reasonable amount to get unit cell output. It is also found that the humidification gives the better performance result slightly.

Characteristics of Fabricated MEA(Membrane Electrode Assembly) on Polymer Electrolyte Membrane Fuel Cell Made by the Screen Printing Method (스크린 프린팅법을 이용하여 제조된 고분자 전해질 연료전지에서 MEA(조합 막 전극)의 특성)

  • 임재욱;최대규;류호진
    • Journal of the Semiconductor & Display Technology
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    • v.2 no.4
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    • pp.27-30
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    • 2003
  • The effect of fabrication method of catalytic layer on electrode performance has been investigated. Brush, spray gun and screen printer were used as fabrication tool and catalytic layers were formed by several methods in screen printing. Direct screen printing on polymer membrane, screen printing on carbon paper, and their combined method were applied. In the electrode fabricated by the screen printing method, Pt loading of Pt/C catalysts could be cut down to 50%, compared with results by the brushing and spraying methods. The best result of electrode was obtained as 0.6 V, at 1 A/$\textrm{cm}^2$ when catalytic layer was formed by the combined way.

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Electrochemical Characteristics of Ion-Exchange Membrane and Charged Mosaic Membrane (복합 하전 모자이크 막과 이온교환 막의 전기적화학적 특성)

  • Yang, Wong-Kang;Song, Myung-Kwan;Cho, Young-Suk
    • Membrane Journal
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    • v.17 no.1
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    • pp.37-43
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    • 2007
  • The effect of anionic and cationic exchange polymer layer on the chronopotentiometry (CP) and current voltage curves (I-V) of charged composite membrane are investigated. Also, the ion transport near the interface between electrolyte and ionic exchange polymer membranes (anionic and cationic ones) and charged mosaic polymer composite membrane is studied. The results show that both anionic and cationic polymer exchange membranes exhibit lower voltage drop over range of applied current density and possess favorable industrial application potentials, especially at low KCl concentration. While the charged mosaic polymer composite membrane didn't show any current-voltage change, irrespective to the type and the concentration of used electrolyte. CP and I-V measurements are effectively used to give some fundamental understanding for ion transport behavior of ion exchange polymer membrane near the interlace.

Photovoltaic Performance of Dye-sensitized Solar Cells assembled with Hybrid Composite Membrane based on Polypropylene Non-woven Matrix

  • Choi, Yeon-Jeong;Kim, Dong-Won
    • Bulletin of the Korean Chemical Society
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    • v.32 no.2
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    • pp.605-608
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    • 2011
  • Hybrid composite membranes were prepared by coating poly(ethylene oxide) and $SiO_2$ particles onto the porous polypropylene nonwoven matrix. Gel polymer electrolytes prepared by soaking the hybrid composite membranes in an organic electrolyte solution exhibited ionic conductivities higher than $1.1{\times}10^{-3}Scm^{-1}$ at room temperature. Dyesensitized solar cell (DSSC) employing the hybrid composite membrane with PEO and 10 wt % $SiO_2$ exhibited an open circuit voltage of 0.77 V and a short circuit current of 10.78 $mAcm^{-2}$ at an incident light intensity of 100 $mWcm^{-2}$, yielding a conversion efficiency of 5.2%. DSSC employing the hybrid composite membrane showed more stable photovoltaic performance than that of the DSSC assembled with liquid electrolyte.