• Title, Summary, Keyword: Proton conductivity

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Modeling of Electrical Conductivity from $\sigma$tot vs. Po21/4 Plot in Wet Atmosphere for High-Temperature Proton-Conducting Oxides

  • Baek, Hyun-Deok
    • The Korean Journal of Ceramics
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    • v.4 no.2
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    • pp.136-140
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    • 1998
  • This work demonstrates a method for modeling of electrical conductivity in high-temperature proton-conducting oxides. Total conductivity was calculated assuming that it comprises partial conductivities contributed by protons, oxygen ions and electron holes. From the polt $\sigma_{tot}$ vs. $po_2\;{1/4}$ in wet atmosphere, thermodynamic and kinetic parameters were obtained representing transport properties such as concentration and mobility of the charge-carrying defects. The formulas for the calculation of partial conduction were derived based on the defect structure of HTPCs. Illustrative calculation were made for $SrCe_{0.95}Yb_{0.05}O_{2.975}$ system.

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Effect of Nickel Addition on Sintering Behavior and Electrical Conductivity of BaCe0.35Zr0.5Y0.15O3-δ

  • An, Hyegsoon;Shin, Dongwook;Ji, Ho-Il
    • Journal of the Korean Ceramic Society
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    • v.56 no.1
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    • pp.91-97
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    • 2019
  • The effect of different Ni-containing additives on the sintering behavior and electric conductivity of the proton conducting electrolyte $BaCe_{0.35}Zr_{0.5}Y_{0.15}O_{3-{\delta}}$ (BCZY5) was investigated. Ni-doped, NiO-added, and $BaY_2NiO_5$(BYN)-added (all 4 mol%) BCZY5 samples were prepared by the solid state synthesis method and sintered at $1400^{\circ}C$ for 6 h. Among the three samples, the onset of densification was observed at the lowest temperature for NiO-added BCZY5, which is attributed to the formation of an intermediate phase at a low melting temperature. The BYN-added sample, where no consumption of the constitutional elements of the electrolyte was expected during sintering, exhibited the highest electrical conductivity whereas the doped sample had the lowest conductivity. The electrical conductivities at $500^{\circ}C$ under humid argon atmosphere were measured to be 2.0, 4.8, and $6.2mS{\cdot}cm^{-1}$ for Ni-doped and NiO- and BYN-added samples, respectively.

Preparation and Characterization of Proton Conducting Membranes by Blending PVC-g-PHEA and PVA

  • Koh, Jong-Kwan;Choi, Jin-Kyu;Seo, Jin-Ah;Zeng, Xiaolei;Kim, Jong-Hak
    • Korean Membrane Journal
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    • v.11 no.1
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    • pp.1-7
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    • 2009
  • This work reports the preparation of proton conductive crosslinked polymer electrolyte membranes by blending poly(vinyl chloride)-g-poly(hydroxyl ethyl acrylate) (PVC-g-PHEA) and poly(vinyl alcohol) (PVA). The PHEA chains of the graft copolymer were crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of polymer matrix and -COOH of SA. The PVC-g-PHEA graft copolymer was synthesized via atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC backbones. Ion exchange capacity (IEC) continuously increased with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. However, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane exhibited a maximum proton conductivity of 0.026 S/cm at 20.0 wt% of SA concentration, which is presumably due to competitive effect between the increase of ionic sites and the crosslinking reaction.

PROPERTY CHANGES OF POLYMER ELECTROLYTE MEMBRANES WITH FREEZE/THAW CYCLES (동결/해동 조건에서 고분자막의 특성 변화 연구)

  • Park Gu-Gon;Lim Nam-Yun;Sohn Young-Jun;Park Jin-Soo;Lee Won-Yong;Kim Sae-Hoon;Lim Tae-Won;Kim Chang-Soo
    • 한국신재생에너지학회:학술대회논문집
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    • pp.281-283
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    • 2005
  • 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 $(at\;-25^{\circ}C)$ 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$(-25\~80^{\circ}C)$ cycle.

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A New Preparation Method of Nafion/Mordenite Composite Membrane for Polymer Electrolyte Membrane Fuel Cell above 100℃ Operation (100℃ 이상에서 작동하는 고분자 전해질형 연료전지용 나피온/Mordenite 복합체 막의 새로운 제조 방법)

  • 곽상희;양태현;김창수;윤기현
    • Journal of the Korean Ceramic Society
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    • v.40 no.2
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    • pp.159-166
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    • 2003
  • The preparation method for composite membranes of high temperature operation above $100^{\circ}C$ for Polymer Electrolyte Membrane Fuel Cells (PEMFCs ) was presented, using perfluorosulfonylfluoride Nafion resin and mordenite, in addition to the physical properties, proton conductivity and single cells performance for it. The composite membranes were fabricated via melting of Nafion resin with various mordenite content. As the increase of mordenite content, at high temperature range, proton conductivity of the composite membrane increased due to the late dehydration rate of existent water in the mordenite. Also, from the result of the current-voltage relationship for single cells under $130^{\circ}C$ operation condition, the composite membrane cell with l0 wt% mordenite content showed better performance than that of the others over the entire current density range. This result indicated that the existent water in the composite membrane with l0 wt% mordenite content was higher than that with the others, thereby maintains its conductivity. Based upon the results of experiments, therefore, a Nafion/mordenite composite membrane prepared by this work is thought to be a satisfactory polymer electrolyte membrane for PEMFC operation above $100^{\circ}C$.

Effect of hydrophobic domain on proton conductivity of sulfonated polyimide membranes (술폰화 폴리이미드 막의 수소이온 전도도에 대한 소수성 영역의 효과)

  • Lee, Chang-Hyun;Sohn, Joon-Yong;Park, Ho-Bum;Lee, Young-Moo
    • Proceedings of the Membrane Society of Korea Conference
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    • pp.61-64
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    • 2004
  • The proton transport through proton exchange membranes is controlled by the distribution of hydrated structure connected with negative-charged fixed ions such as phosphonic acid, carboxylic acid and sulfonic acid, or water molecules within the membrane.(omitted)

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Solid State NMR Studies of Proton Conducting Polymer, Poly(vinyl phosphonic) acid

  • Lee, Young-Joo;Bingol Bahar;Murakhtina Tatiana;Sebastiani Daniel;Ok, Jong-Hwa;Meyer Wolfgang H.;Wegner Gerhard;Spiess Hans Wolfgang
    • Proceedings of the Polymer Society of Korea Conference
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    • pp.347-347
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    • 2006
  • Polymers containing poly(vinyl phosphonic) acid segments are promising candidates to be used as proton conducting membranes. Solid state NMR spectroscopy represents an ideal probe of proton motion on the molecular level, because it allows us to selectively detect the nuclei of interest. In this paper, we apply solid state NMR methods to poly(vinyl phosphonic) acid in order to demonstrate that the proton conduction of poly(vinyl phosphonic acid) results from P-OH proton through hydrogen bonding and that the condensation of phosphonic acid leads to decrease in proton conductivity. $^{1}H\;and\;^{31}P$ solid state NMR experiments are supported by quantum chemical computation of NMR parameters.

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Preparation and Characterization of the $H_3PO_4$-doped Sulfonated Poly(aryl ether benzimidazole) Membrane for Polymer Electrolyte Membrane Fuel Cell (고분자전해질 연료전지용 인산 도핑 술폰화 폴리아릴에테르벤즈이미다졸 고분자전해질 막의 제조 및 특성)

  • Hong, Young-Taik;Jeong, Jin-Ju;Yoon, Kyung-Sock;Choi, Jun-Kyu;Kim, Young-Jun
    • Membrane Journal
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    • v.16 no.4
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    • pp.276-285
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    • 2006
  • Acid-doped sulfonated poly(aryl ether benzimidazole) (S-PAEBI) copolymers were synthesized by a direct polymerization technique and a doping with phosphoric acid as a dopant, and the polymer electrolyte membranes were fabricated from them by a solution casting method. To optimize the reaction condition, the degree of sulfonation and doping level were varied in the ranges of $0{\sim}60%\;and\;0.7{\sim}5.7$, respectively. Physiochemical properties of the doped membranes were investigated by AFM, TGA and the measurement of proton conductivity. It was found that proton conductivities depend on doping levels of membranes. Conductivity determined at the condition of $130^{\circ}C$ and no humidity was $7.3{\times}10^{-2}S/cm$ for the $H_3PO_4$-doped PAEBI membrane with a doping level of 5.7.

Preparation of Proton Conducting Anhydrous Membranes Using Poly(vinyl chloride) Comb-like Copolymer (Poly(vinyl chloride) 빗살형 공중합체를 이용한 무가습 수소이온 전도성 전해질막의 제조)

  • Kim, Jong-Hak;Koh, Joo-Hwan;Seo, Jin-Ah;Ahn, Sung-Hoon;Zeng, Xiaolei
    • Membrane Journal
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    • v.19 no.2
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    • pp.89-95
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    • 2009
  • A comb-like copolymer consisting of a poly(vinyl chloride) backbone and poly(hydroxy ethyl acrylate) side chains, i.e. PVC-g-PHEA, was synthesized through atom transfer radical polymerization (ATRP). This comb-like copolymer was crosslinked with 4,5-imidazole dicarboxylic acid (IDA) via the esterification of the -OH groups of PHEA in the graft copolymer and the -COOH groups of IDA. Upon doping with phosphoric acid (PA, $H_3PO_4$) to form imidazole-PA complexes, the proton conductivity of the membranes continuously increased with increasing PA content. A maximum proton conductivity of 0.011 S/cm was achieved at $100^{\circ}C$ under anhydrous conditions. The PVC-g-PHEA/IDA/PA complex membranes exhibited good mechanical properties, i.e. 575 MPa of Young's modulus, as determined by a universal testing machine (UTM). Thermal gravimetric analysis (TGA) shows that the membranes were thermally stable up to $200^{\circ}C$.

Preparation of Anhydrous Crosslinked Graft Copolymer Electrolyte Membrane (무가습 가교 가지형 공중합체 전해질 막의 제조)

  • Roh, Dong-Kyu;Koh, Joo-hwan;Park, Jung-tae;Seo, Jin-ah;Kim, Jong-hak
    • 한국신재생에너지학회:학술대회논문집
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    • pp.270-273
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    • 2009
  • A comb-like copolymer consisting of a poly(vinylidene fluoride-co-chlorotrifluoro-ethylene) backbone and poly(hydroxy ethyl acrylate) side chains, i.e. P(VDF-co-CTFE)-g-PHEA, was synthesized through atom transfer radical polymerization (ATRP) using CTFE units as a macroinitiator. Successful synthesis and a microphase-separated structure of the copolymer were confirmed by proton nuclear magnetic resonance (1H-NMR), FT-IR spectroscopy, and transmission electron microscopy (TEM). This comb-like polymer was crosslinked with 4,5-imidazole dicarboxylic acid (IDA) via the esterification of the -OH groups of PHEA and the -COOH groups of IDA. Upon doping with phosphoric acid ($H_3PO_4$) to form imidazole-$H_3PO_4$ complexes, the proton conductivity of the membranes continuously increased with increasing $H_3PO_4$ content. A maximum proton conductivity of 0.015 S/cm was achieved at $120^{\circ}C$ under anhydrous conditions. In addition, these P(VDF-co-CTFE)-g-PHEA/IDA/$H_3PO_4$ membranes exhibited good mechanical properties (765 MPa of Young's modulus), and high thermal stability up to $250^{\circ}C$, as determined by a universal testing machine (UTM) and thermal gravimetric analysis (TGA), respectively.

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