• Title, Summary, Keyword: Proton conductivity

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Preparation of Solid Polymer Electrolytes of PSf-co-PPSS/Heterooolyacid [HPA] Composite Membrane for Hydrogen Production via Water Elecrolysis (PSf-co-PPSS/HPA를 이용한 수소제조 수전해용 고체 고분자 전해질 복합 막의 제조)

  • Jung, Yun-Kyo;Lee, Hyuck-Jae;Jang, In-Young;Hwang, Gab-Jin;Bae, Ki-Kwang;Sim, Kyu-Sung;Kang, An-Soo
    • Transactions of the Korean hydrogen and new energy society
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    • v.16 no.2
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    • pp.103-110
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    • 2005
  • Proton conducting solid polymer electrolyte (SPE) membranes have been used in many energy technological applications such as water electolysis, fuel cells, redox-flow battery, and other electrochemical devices. The availability of stable membranes with good electrochemical characteristics as proton conductivity at high temperatures above 80 $^{\circ}C$ and low cost are very important for its applications. However, the presently available perfluorinated ionomers are not applicable because of high manufacturing cost and high temperature use to the decrease in the proton conductivity and mechanical strength. In order to make up for the weak points, the block copolymer (BPSf) of polysulfone and poly (phenylene sulfide sulfone) were synthesized and sulfonated. The electrolyte membranes were prepared with phosphotungstic acid (HPA)/sulfonated BPSf via solution blending. This study would be desirable to investigate the interaction between the HPA and sulfonated polysulfone. The results showed that the characteristics of SPSf/HPA blend membrane was a better than Nafion at high temperature, 100 $^{\circ}C$. These membranes proved to have a high proton conductivity, $6.29{\times}10-2$ S/cm, a water content, 23.9%, and a ion exchange capacity, 1.97 meq./g dry membrane. Moreover, some of the membranes kept their high thermal and mechanical stability.

Influence of Silica Content in Crosslinked PVA/PSSA_MA/Silica Hybrid Membrane for Direct Methanol Fuel Cell (DMFC)

  • Kim, Dae-Sik;Guiver, Michael D.;Seo, Mu-Young;Cho, Hyun-Il;Kim, Dae-Hoon;Rhim, Ji-Won;Moon, Go-Young;Nam, Sang-Yong
    • Macromolecular research
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    • v.15 no.5
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    • pp.412-417
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    • 2007
  • In the present study, crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at different temperatures using poly(styrene sulfonic acid-co-maleic acid) (PSSA_MA) (PVA:PSSA_MA = 1:9). The hybrid mem-branes were prepared by varying the TEOS content between 5 and 30 wt%. The PSSA_MA was used both as a crosslinking agent and the hydrophilic group donor ($-SO_3H$ and/or-COOH). The proton conductivity increased with up to 20 wt% TEOS, but decreased above this level, although the water content decreased with increasing TEOS content. This result suggests that the silica doped into the membrane improved the formation of proton-conduction pathways due to the absorption of molecular water. The PVA/PSSA_MA/Silica containing TEOS 20% showed both high proton conductivity (0.026 S/cm at $90^{\circ}C$) and low methanol permeability ($5.55{\times}10^{-7}cm^2/s$).

Reduction of Methanol Crossover in a Direct Methanol Fuel Cell by Using the Pt-Coated Electrolyte Membrane

  • Jung, Eun-Mi;Rhee, Young-Woo;Peck, Dong-Hyun;Lee, Byoung-Rok;Kim, Sang-Kyung;Jung, Doo-Hwan
    • Journal of the Korean Electrochemical Society
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    • v.11 no.1
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    • pp.1-5
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    • 2008
  • A Pt-layer was deposited on the anode side of a Nafion membrane via a sputtering method in order to reduce methanol crossover in a direct methanol fuel cell (DMFC). The methanol permeation and the proton conductivity through the modified membranes were investigated. The performances of the direct methanol fuel cell were also tested using single cells with a Nafion membrane and the modified membranes. The Pt-layers on the membrane blocked both methanol crossover and proton transport through the membranes. Methanol permeability and proton conductivity decreased with an increase of the platinum layer thickness. At methanol concentration of 2 M, the DMFC employing the modified membrane with a platinum layer of 66 nm-thickness showed similar performance to that of a DMFC with a bare Nafion membrane in spite of the lower proton conductivity of the former. The maximum power density of the cell using the modified membrane with a platinum layer of 66 nm-thickness increased slightly while that of the cell with the bare membrane decreased abruptly when a methanol solution of 6M was supplied.

Polymer Electrolyte Membranes of Poly(Styrene-Butadiene-Styrene) Star Triblock Copolymer for Fuel Cell (연료전지용 Poly(Styrene-Butadiene-Styrene) Star Triblock Copolymer의 고분자 전해질 분리막)

  • Garcia, Edwin D.;Jung, Bumsuk
    • Membrane Journal
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    • v.29 no.5
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    • pp.252-262
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    • 2019
  • A sulfonated star branched poly(styrene-b-butadiene-b-styrene) triblock copolymer (SSBS) was synthesized with varying degrees of sulfonation. The effective sulfonation on the butadiene block was confirmed by FT-IR spectroscopy. Ion exchange capacity by titration was used to determine the degree of sulfonation. The synthesized polymer observed enhanced water uptake and proton conductivity. At room temperature, the SSBS with 25 mol% degree of sulfonation showed an outstanding proton conductivity of 0.114 S/cm, similar to that of commercial membrane, Nafion. The effect of temperature at constant relative humidity on conductivity resulted to a remarkable increase in proton conductivity. Methanol permeability studies showed a value lower than Nafion for all the sulfonated membranes. Structural nature observed using AFM showed that the membranes observed microphase separated nanostructures and the connectivity of the interionic channels.

Proton Conductivity and Methanol Permeability of Sulfonated Poly(aryl ether sulfone)/Modified Graphene Hybrid Membranes (술폰화 폴리아릴렌에테르술폰/개질된 그라핀 복합막의 이온전도도 및 메탄올 투과도)

  • Huh, Hoon;Kim, Deuk-Ju;Nam, Sang-Yong
    • Membrane Journal
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    • v.21 no.3
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    • pp.247-255
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    • 2011
  • In this study, to obtain good dispersity of graphene which has excellent conductivity and mechanical strength, the graphene was modified by two different methods. Then the SPAES/graphene hybrid membranes were fabricated from different graphene contents. We compared performance of composite membrane with different preparing method of graphene and content of modified graphene. The morphology of the composite membranes has been investigated using SEM. Chemical structure of modified graphene was analyzed using by FT-IR and EDX. The proton conductivity and methanol permeability of the hybrid membranes were studied with changing graphene content from 0.5 to 3.0 wt.%. The SPAES/modified graphene composite membranes showed high proton conductivity (0.21 S/cm) compared with the SPAES membrane (0.09 S/cm) at $80^{\circ}C$ and 100% relative humidity condition. And the methanol permeability was decreased linearly as the content of modified graphene increased from 0 to 1.5 wt%.

Studies on the Addition of the Hydroquinonesulfonic Acid to Poly(vinyl alcohol)/poly(acrylic acid-co-maleic acid) Membranes to Improve the Ion Conductivity for Fuel Cell Applications (Poly(vinyl alcohol)/poly(acrylic acid-co-maleic acid) 이온교환막에 이온전도도 향상을 hydroquinonesulfonic acid 첨가 연구)

  • 임지원;황호상
    • Membrane Journal
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    • v.14 no.1
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    • pp.44-52
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    • 2004
  • This paper concerns the development of a cationic polymeric membranes for direct methanol fuel cell. The crosslinked poly(vinyl alcohol) (PVA) membranes with poly(acrylic acid-co-maleic acid) (PAM) and hydroquinonesulfonic acid (HQSA) as the crosslinking agents were prepared according to the amount of crosslinking agents. The resulting membranes were characterized in terms of methanol permeability, proton conductivity, water content and ion exchange capacity. The methanol permeability and proton conductivity increased with increasing PAM content up to 9 wt% and then decreased. This trend is considered the effect of the cross linking rather than the introduction of hydrophilic groups. When the HQSA contents were varied, no interesting increases of proton conductivity, water content and ion exchange capacity were found.

Synthesis and Characterization of Sulfonated Poly(arylene ether) Polyimide Multiblock Copolymers for Proton Exchange Membranes

  • Lee, Hae-Seung;Roy Abhishek;Badami Anand S.;McGrath James E.
    • Macromolecular research
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    • v.15 no.2
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    • pp.160-166
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    • 2007
  • Novel multiblock copolymers, based on segmented sulfonated hydrophilic-hydrophobic blocks, were synthesized and investigated for their application as proton exchange membranes. A series of segmented sulfonated poly(arylene ether sulfone)-b-polyimide multiblock copolymers, with various block lengths, were synthesized via the coupling reaction between the terminal amine moieties on the hydrophilic blocks and naphthalene anhydride functionalized hydrophobic blocks. Successful imidization reactions required a mixed solvent system, comprised of NMP and m-cresol, in the presence of catalysts. Proton conductivity measurements revealed that the proton conductivity improved with increasing hydrophilic and hydrophobic block lengths. The morphological structure of the multiblock copolymers was investigated using tapping mode atomic force microscopy (TM-AFM). The AFM images of the copolymers demonstrated well-defined nanophase separated morphologies, with the changes in the block length having a pronounced effect on the phase separated morphologies of the system. The self diffusion coefficient of water, as measured by $^1H$ NMR, provided a better understanding of the transport process. Thus, the block copolymers showed higher values than Nafion, and comparable proton conductivities in liquid water, as well as under partially hydrated conditions at $80^{\circ}C$. The new materials are strong candidates for use in PEM systems.

Synthesis and Characterization of Polybenzimidazole Random Copolymers Containing Methylene Chain for High Temperature PEMFC (고온 PEMFC용 메틸렌 사슬을 포함하는 폴리벤즈이미다졸 랜덤 공중합체의 합성과 특성 분석)

  • HAN, DAEUN;YOO, DONG JIN
    • Transactions of the Korean hydrogen and new energy society
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    • v.29 no.6
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    • pp.578-586
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    • 2018
  • In this study, we prepared the modified PBI random copolymer to reduce the problems of the pristine PBI about low solubility and proton conductivity. The random copolymer was synthesized from suberic acid, 5-aminoisophthalic acid, and 3,3'-diaminobenzidine to obtain $X_1Y_9$, $X_1Y_1$, $X_9Y_1$. Then, the membrane was fabricated by using solvent casting method with methanesulfonic acid at $140^{\circ}C$. Subsequently, the membrane was doped with phosphoric acid at $40^{\circ}C$. The chemical structure of the polymers was characterized by FT-IR. In addition, the physiochemical properties of the PBI were investigated by TGA, oxidative stability, acid uptake. Finally, the proton conductivity was measured at $100-180^{\circ}C$ without humidification. As the result, $X_1Y_9$ PBI random copolymer membrane showed higher conductivity.