• Title, Summary, Keyword: Proton conductivity

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High Proton Conductivity Crosslinked Sulfonated Polyimide Membranes (높은 수소이온전도성을 가진 가교술폰화폴리이미드막)

  • Lee, Chang-Hyun;Park, Chi-Hoon;Park, Ho-Bum;Lee, Young-Moo
    • Proceedings of the Membrane Society of Korea Conference
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    • pp.61-63
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    • 2003
  • A major research objective related to proton exchange membrane(PEM) for DMFC is to achieve high proton conductivity over 10$^{-2}$ S/cm, high hydrolytic stability and low methanol permeability with low cost base materials. for the purpose, a lot of thermoplastic polymers such as polysulfones, polyethersulfone, polyetherketones, polyimides, polyoxadiazole, polyphosphazene and polybenzimidazol have been investigated. Amongst those polymers, polyimides have been suggested as a potential PEM due to their excellent thermal, chemical stability and good mechanical properties. Generally, polyimides are synthesized by polycondensation with numerious diamines and dianhydriedes. In our study, polyimide was prepared using non-sulfonated diamine, sulfonated diamine directly synthesized by fuming sulfuric acid, and naphthalenic dianhydride to improve the hydrolysis stability under acidic condition. Through monomer sulfonation-subsequent polymerization method, the high proton conducting capability and the desired sulfonation level were effectively controlled at the same time. To reduce severe methanol transport through the membrane, the chemical crosslinking among polymer chains was introduced using various crosslinking agents with different chain lengths. The crosslinked sulfonated polyimide membranes showed high proton conductivity up to 8.09$\times$10$^{-2}$ S/cm and from crosslinking effect methanol transport through the membranes was considerably reduced as compared with unmodified membranes. For increase of chain length of crosslinker, methanol permeability was adversely reduced to 10$^{-8}$ $\textrm{cm}^2$/s due to decrease of IEC and increase of crosslinking desity.

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Synthesis and Characterization of Phosphoric Acid-doped Poly (2,5-benzimidazole) Membrane for High Temperature Polymer Electrolyte Membrane Fuel Cells (고온 고분자 연료전지용 인산 도핑 폴리(2,5-벤지이미다졸) 막의 제조 및 특성)

  • Nguyen, Thi Xuan Hien;Mishra, Ananta Kumar;Choi, Ji-Sun;Kim, Nam-Hoon;Lee, Joong-Hee
    • Transactions of the Korean hydrogen and new energy society
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    • v.23 no.1
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    • pp.26-33
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    • 2012
  • Phosphoric acid-doped poly (2,5-benzimidazole) (DABPBI) was prepared by condensation polymerization of 3,4-diaminobenzoic acid for high temperature proton electrolyte membrane fuel cells. The membranes were casted directly using a hot-press unit and characterized by fourier transform infrared spectroscopy, thermogravimetric analysis, conductivity measurement, scanning electron microscopy and tensile test. The proton conductivities of DABPBI are observed to be 0.062 and 0.018 $S{\cdot}cm^{-1}$ under 30 and 1% relative humidity, respectively at a temperature of $120^{\circ}C$ which is appreciably higher than that of Nafion 115 under similar conditions. The DABPBI membrane has demonstrated excellent thermo- mechanical properties and proton conductivity suggesting its suitability as a high temperature membrane.

The Effect of Proton Conductivity of SPEEK Composite Membrane with Organic Compounds for DMFC

  • You, S.K.;Kim, H.J.;Shin, H.S.;Kim, J.S.;Choi, W.K.;Park, S.G.
    • Journal of the Korean Electrochemical Society
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    • v.12 no.2
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    • pp.167-172
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    • 2009
  • Direct methanol fuel cells(DMFCs) are receiving significant attention in the portable power source and electric vehicular transportation because of its high energy efficiency as liquid fuel, low cost, and no requirement of fuel reforming process. In this study, we synthesized the Sulfonated poly(ether ether ketone) (SPEEK) to evaluate the possibility of use as a proton exchange membrane for DMFC. And poly(vinylidienedifluoride) (PVDF) was used to increase proton conductivity in SPEEK and simultaneously to prevent methanol transport through the cross linked membrane. Furthermore, in order to improve the electrical composite properties for DMFC applications.

Preparation and Characterization of Proton Conducting Composite Membranes From P(VDF-CTFE)-g-PSPMA Graft Copolymer and Heteropolyacid

  • Seo, Jin-Ah;Roh, Dong-Kyu;Koh, Jong-Kwan;Kim, Jong-Hak
    • Korean Membrane Journal
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    • v.10 no.1
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    • pp.20-25
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    • 2008
  • Proton conducting composite membranes were prepared by solution blending of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(sulfopropyl methacrylate) (P(VDF-CTFE)-g-PSPMA) graft copolymer and heteropolyacid (HPA). The P(VDF-CTFE)-g-PSPMA graft copolymer was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of P(VDF-CTFE). FT-IR spectroscopy revealed that HPA nanoparticles were incorporated into the graft copolymer via hydrogen bonding interactions. The water uptake of membranes continuously decreased with increasing HP A concentration up to 45wt%, after which it slightly increased. It is presumably due to the decrease in number of water absorption sites due to hydrogen bonding interaction between the HP A particles and the polymer matrix. The proton conductivity of membranes increased with increasing HPA concentration up to 45wt%, resulting from both the intrinsic conductivity of HP A particles and the enhanced acidity of the sulfonic acid of the graft copolymer.

Synthesis and characterization of sulfonated mutiphenyl conjugated polyimide for PEMFC

  • Ryu, Taewook;Sutradhar, Sabuj Chandra;Ahmed, Faiz;Choi, Kunyoung;Yang, Hanmo;Yoon, Sujin;Lee, Sungkwun;Kim, Whangi
    • Journal of Industrial and Engineering Chemistry
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    • v.49
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    • pp.99-104
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    • 2017
  • A new monomer, di-sulfuricacid-1,1-bis(4-aminophenyl)-2,2-diphenylethylene (SBAPDPE), was synthesized by direct sulfonation of the parent diamine, 1,1-bis(4-aminophenyl)-2,2-diphenylethylene (BAPDPE) using concentrated sulfuric acid. A series of the side-chain-type sulfonated conjugated tetraphenylethylene polyimides (SCTPPIs) with different degrees of sulfonation were prepared from dianhydrides with SBAPDPE and non-sulfonated diamine. The SCTPPIs generally showed good solubility in m-cresol and DMSO. The membranes were studied by FT-IR, $^1H$ NMR spectroscopy, and TGA. Sorption experiments were conducted to observe the interaction of sulfonated polymers with water. The ion exchange capacity (IEC) and proton conductivity were evaluated with increase of degree of sulfonation.

A Low-Density Graphite-Polymer Composite as a Bipolar Plate for Proton Exchange Membrane Fuel Cells

  • Dhakate, S.R.;Sharma, S.;Mathur, R.B.
    • Carbon letters
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    • v.14 no.1
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    • pp.40-44
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    • 2013
  • The bipolar plate is the most important and most costly component of proton exchange membrane fuel cells. The development of a suitable low density bipolar plate is scientifically and technically challenging due to the need to maintain high electrical conductivity and mechanical properties. Here, bipolar plates were developed from different particle sizes of natural and expanded graphite with phenolic resin as a polymeric matrix. It was observed that the particle size of the reinforcement significantly influences the mechanical and electrical properties of a composite bipolar plate. The composite bipolar plate based on expanded graphite gives the desired mechanical and electrical properties as per the US Department of Energy target, with a bulk density of 1.55 $g.cm^{-3}$ as compared to that of ~1.87 $g.cm^{-3}$ for a composite plate based on natural graphite (NG). Although the bulk density of the expanded-graphite-based composite plate is ~20% less than that of the NG-based plate, the I-V performance of the expanded graphite plate is superior to that of the NG plate as a consequence of the higher conductivity. The expanded graphite plate can thus be used as an electromagnetic interference shielding material.

Development and Charateriztion of Molybdophosphoric Acid Bonded Polyether Ether Ketone Polymer Composite Membrane for Water Electrolysis (수전해용 MoPA 결합된 폴리에테르 에테르 케톤 고분자 복합막의 개발 및 특성)

  • KIM, MIN JIN;KIM, BO YOUNG;MOON, SANG-BONG;CHUNG, JANG HOON
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.4
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    • pp.338-344
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    • 2017
  • Polyoxometal molybdophosphoric acid (MoPA) bonded polyether ether ketone (PEEK) composite membrane for water electrolysis has been investigated. The composited membrane, covalently cross linked (CL) sulfonated polyether ether ketone (SPEEK) with a bonded MoPA, was prepared in sulfonation of PEEK, cross linkage reaction with 1,4-diiodobutane, and addition with MoPA. PEEK was covalently cross-linked with 1,4-diiodobutane to improve mechanical strength and was added with MoPA to increase proton conductivity. MoPA should be fixed to back bone of SPEEK to prevent bleeding out. Therefore, the carbonyl group of SPEEK was reduced with NaBH4 and 3-isocyanatepropyltriethoxysilane (ICPTES) was added. The MoPA bonded composite was produced in the reaction of MoPA with 3-mercaptopropyltrimethoxvsilane (MPTMS). In conclusion, MoPA bonded CL-SPEEK composite membrane featured 0.129 S/cm of proton conductivity at $80^{\circ}C$, and 2,156 hours of chemical stability in Fenton test. These properties are better than those of membranes of other SPEEK system.

Perfluorinated Sulfonic Acid Ionomer-PTFE Pore-filling Membranes for Polymer Electrolyte Membrane Fuel Cells (고분자전해질연료전지용 과불소계 술폰화 이오노머-PTFE 강화막)

  • Kang, Seong Eun;Lee, Chang Hyun
    • Membrane Journal
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    • v.25 no.2
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    • pp.171-179
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    • 2015
  • Perfluorinated sulfonic acid ionomers (PFSAs) have been widely as solid electrolyte materials for polymer electrolyte membrane fuel cells, since they exhibit excellent chemical durability under their harsh application conditions as well as good proton conductivity. Even PFSA materials, however, suffer from physical failures associated with repeated membrane swelling and deswelling, resulting in fairly reduced electrochemical lifetime. In this study, pore-filling membranes are prepared by impregnating a Nafion ionomer into the pore of a porous PTFE support film and their fundamental characteristics are evaluated. The developed pore-filling membranes exhibit extremely high proton conductivity of about $0.5S\;cm^{-1}@90^{\circ}C$ in liquid water.

Effect of Annealing of Nafion Recast Membranes Containing Ionic Liquids

  • Park, Jin-Soo;Shin, Mun-Sik;Sekhon, S.S.;Choi, Young-Woo;Yang, Tae-Hyun
    • Journal of the Korean Electrochemical Society
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    • v.14 no.1
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    • pp.9-15
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    • 2011
  • The composite membranes comprising of sulfonated polymers as matrix and ionic liquids as ion-conducting medium in replacement of water are studied to investigate the effect of annealing of the sulfonated polymers. The polymeric membranes are prepared on recast Nafion containing the ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ($EMIBF_4$). The composite membranes are characterized by thermogravitational analyses, ion conductivity and small-angle X-ray scattering. The composite membranes annealed at $190^{\circ}C$ for 2 h after the fixed drying step showed better ionic conductivity, but no significant increase in thermal stability. The mean Bragg distance between the ionic clusters, which is reflected in the position of the ionomer peak (small-angle scattering maximum), is larger in the annealed composite membranes containing $EMIBF_4$ than the non-annealed ones. It might have been explained to be due to the different level of ion-clustering ability of the hydrophilic parts (i.e., sulfonic acid groups) in the non- and annealed polymer matrix. In addition, the ionic conductivity of the membranes shows higher for the annealed composite membranes containing $EMIBF_4$. It can be concluded that the annealing of the composite membranes containing ionic liquids due to an increase in ion-clustering ability is able to bring about the enhancement of ionic conductivity suitable for potential use in proton exchange membrane fuel cells (PEMFCs) at medium temperatures ($150-200^{\circ}C$) in the absence of external humidification.