• Title/Summary/Keyword: Proton conductivity

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Proton Conductivity Measurement Using A.C. Impedance Spectroscopy for Proton Exchange Membrane

  • Lee, Chang Hyun;Park, Ho Bum;Lee, Young Moo
    • Korean Membrane Journal
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    • v.6 no.1
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    • pp.1-9
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    • 2004
  • The impedance and the subsequent proton conductivity of Nafion$\^$/ membranes as standard samples were measured and compared via the two-probe method and the four-probe method using the prepared impedance measurement system. The different impedance behavior for the same membrane was observed at the fully hydrated state in the Nyquist impedance plot. The effect of the humidity and the temperature on the proton conduction through a membrane was investigated and compared with two different cell configurations.

Characterization of Polymer Blends of Poly(ether sulfone)/Sulfonated Poly(ether ether ketone) for DMFC (직접메탄올 연료전지용 Poly(ether sulfone)/Sulfonated Poly(ether ether ketone) 블렌드 막의 특성 연구)

  • Cheon, Hun Sang;Lee, Choong Gon;Hong, Seong Uk
    • Applied Chemistry for Engineering
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    • v.16 no.1
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    • pp.144-149
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    • 2005
  • Sulfonated poly(ether ether ketone) (SPEEK) was blended with poly(ether sulfone) (PES) at various compositions. To investigate the possibility of using the blend membranes as polymer electrolyte membranes for direct methanol fuel cell, the blend membranes were characterized in terms of methanol permeability, proton conductivity, ion exchange capacity, and water content. Both proton conductivity and methanol permeability of SPEEK were relatively high. As the amount of PES increased, methanol permeability decreased more rapidly compared to proton conductivity. The experimental results indicated that the blend membrane with 40 wt% PES was the best choice in terms of the ratio of proton conductivity to methanol permeability.

Proton Conductivity of Niobium Phosphate Glass Thin Films

  • Kim, Dae Ho;Park, Sung Bum;Park, Yong-il
    • Korean Journal of Materials Research
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    • v.28 no.5
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    • pp.308-314
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    • 2018
  • Among the fuel cell electrolyte candidates in the intermediate temperature range, glass materials show stable physical properties and are also expected to have higher ion conductivity than crystalline materials. In particular, phosphate glass has a high mobility of protons since such a structure maintains a hydrogen bond network that leads to high proton conductivity. Recently, defects like volatilization of phosphorus and destruction of the bonding structure have remarkably improved with introduction of cations, such as Zr4+ and Nb5+, into phosphate. In particular, niobium has proton conductivity on the surface because of higher surface acidity. It can also retain phosphorus content during heat treatment and improve chemical stability by bonding with phosphorus. In this study, we fabricate niobium phosphate glass thin films through sol-gel processing, and we report the chemical stability and electrical properties. The existence of the hydroxyl group in the phosphate is confirmed and found to be preserved at the intermediate temperature region of $150-450^{\circ}C$.

Hybrid nanocomposite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica for direct methanol fuel cells

  • Khosravi, Yasamin;Hassanajili, Shadi;Moslemin, Mohammad Hosein;Tabatabaei, Masumeh
    • Korean Journal of Chemical Engineering
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    • v.34 no.2
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    • pp.328-339
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    • 2017
  • Composite membranes of sulfonated poly(ethersulfone)/1,1-carbonyl diimidazole/1-(3-aminopropyl)-silane/silica (SPES/CDI/AS/$SiO_2$) with silica of various contents (3, 5 and 8 wt%) were prepared as electrolytes for direct methanol fuel cells (DMFCs). Comparison was made with pure SPES and SPES/$SiO_2$. The properties of the composite membranes were studied by FTIR, TGA, XRD, water and methanol uptake, proton conductivity. SPES/CDI/AS/$SiO_2$ membranes were also characterized by scanning electron microscopy (SEM), which showed good adhesion between the modified sulfonic acid ($-SO_3H$) groups of SPES and silica because of cross-linking with covalent bond formation and reduced cavities in the composites. This effect played an important role in reducing water uptake, methanol uptake and methanol permeability of the SPES/CDI/AS/$SiO_2$ composites. The water and methanol uptake and also methanol permeability of the SPES/CDI/AS/$SiO_2$ composite membrane with 8% $SiO_2$ were found in the order 3.58%, 2.48% and $1.91{\times}10^{-7}(cm^2s^{-1})$, lower than those of SPES and Nafion 117. In SPES membrane of 16.94% level of sulfonation, the proton conductivity was 0.0135 s/cm at $25^{\circ}C$, which approached that of Nafion 117 under the same conditions. Also, the proton conductivity of the SPES/CDI/AS/$SiO_2$ 8% membrane was 0.0186 s/cm, which was higher than that of SPES at room temperature. The preparation of SPES/$SiO_2$ composites in the presence of AS and CDI, led to 63%, 56% and 64% reduction of water uptake, methanol uptake and methanol permeability, respectively without a sharp drop in proton conductivity of the composite membranes which featured a good balance between high proton conductivity, water and methanol uptake of SPES/CDI/AS/$SiO_2$ membranes.

The Effect of sGO Content in sPEEK/sGO Composite Membrane for Unitized Regenerative Fuel Cell (일체형 재생연료전지 적용을 위한 sGO 함량 변화에 따른 sGO/sPEEK 복합막의 특성 평가)

  • Jung, Ho-Young;Kim, Min-Woo;Lim, Ji-Hun;Choi, Jin H.;Roh, Sung-Hee
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.1
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    • pp.127-131
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    • 2016
  • Polymer electrolyte membrane for unitized regenerative fuel cells requires high proton conductivity, high dimensional stability, low permeability, and low cost. However, DuPont's Nafion which is a commercial polymer electrolyte membrane has high permeability, high cost, and decreasing proton conductivity and dimensional stability over $80^{\circ}C$. To address these problems, sulfonated poly ether ether ketone (sPEEK) which is a low cost hydrocarbon polymer is selected as matrix polymer for the preparation of polymer electrolyte membrane. In addition, composite membrane with improved proton conductivity and dimensional stability is prepared by introducing sulfonated graphene oxide (sGO). The fundamental properties of polymer electrolyte membranes are analyzed by investigating membrane's water content, dimensional stability, proton conductivity, and morphology. The cell test is conducted to consider the possibility of application of sPEEK/sGO composite membrane for an unitized regenerative fuel cell.

Synthesis and Characterization of Sulfonated Poly(phthalazinone ether sulfone)(sPPES)/Silica Membrane for Proton Exchange Membrane Materials

  • Kim, Dae Sik;Park, Ho Bum;Nam, Sang Young;Rhim, Ji Won;Lee, Young Moo
    • Korean Membrane Journal
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    • v.6 no.1
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    • pp.44-54
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    • 2004
  • Organic-inorganic composite membranes based on sulfonated poly(phthalazinone ether sulfone) (sPPES)/silica hybrid were prepared using the sol-gel process under acidic conditions. The sulfonation of PPES with concentrated sulfuric acid as sulfonation agent was carried out to prepare proton exchange membrane material. The behaviors of the proton conductivity and methanol permeability are depended on the sulfonation time (5-100 hr). The hybrid membranes composed of highly sulfonated PPES (IEC value: 1.42 meq./g) and silica were fabricated from different silica content (5-20 wt%) in order to achieve desirable proton conductivity and methanol permeability demanded for fuel cell applications. The silica particles within membranes were used for the purpose of blocking excessive methanol cross-over and for forming the path way to transport of the proton due to absorbing water molecules with ≡SiOH on silica. The presence of silica particles in the organic polymer matrix results in hybrid membranes with reduced methanol permeability and improved proton conductivity.

Preparation and Characterization of Sulfonated Poly(phthalazinone ether sulfone ketone) (SPPESK)/Silica Hybrid Membranes for Direct Methanol Fuel Cell Applications

  • Kim, Dae-Sik;Shin, Kwang-Ho;Park, Ho-Bum;Lee, Young-Moo
    • Macromolecular Research
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    • v.12 no.4
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    • pp.413-421
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    • 2004
  • Sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) membranes and sol-gel derived SPPESK/silica hybrid membranes have been investigated as potential polymer electrolyte membranes for direct methanol fuel cell (DMFC) applications. In comparison with the SPPESK membrane, the SPPESK/silica membranes exhibited higher water content, improved proton conductivity, and lower methanol permeability. Notably, the silica embedded in the membrane acted as a material for reducing the fraction of free water and as a barrier for methanol transport through the membrane. From the results of proton conductivity and methanol permeability studies, we suggest that the fractions of bound and free water should be optimized to obtain desirable proton conductivities and methanol permeabilities. The highly sulfonated PPESK hybrid membrane (HSP-Si) displayed higher proton conductivity (3.42 ${\times}$ 10$^2$ S/cm) and lower methanol permeability (4.15 ${\times}$ 10$\^$7/ $\textrm{cm}^2$/s) than those of Nafion 117 (2.54 ${\times}$ 10$^2$ S/cm; 2.36 ${\times}$ 10$\^$6/ $\textrm{cm}^2$/s, respectively) at 30$^{\circ}C$. This characteristic of the SPPESK/silica membranes is desirable for future applications related to DMFCs.

Preparation and Their Characterization of Blended Polymer Electrolyte Membranes of Polysulfone and Sulfonated Poly(ether ether ketone) (Polysulfone/SPEEK 블랜드 고분자 전해질 막 제조 및 특성 연구)

  • Cheon, Hun-Sang;Oh, Min;Hong, Seong-Uk
    • Membrane Journal
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    • v.13 no.1
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    • pp.47-53
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    • 2003
  • Poly(ether ether ketone)(PEEK) was sulfonated using sulfuric acid and blended with polysulfone with various ratios. The blended polymer electrolyte membranes were characterized in terms of methanol permeability, proton conductivity and ion exchange capacity. As the amount of sulfonated PEEK increased, both methanol permeability and proton conductivity increased. This was due to the increase of ion exchange capacity. The experimental results indicated that the blend membrane with 20% polysulfone was the best choice In terms of the ratio of proton conductivity to methanol permeability.

Effect of the Molecular Weight of Poly(vinyl alcohol) Blended with Sulfonated Polysulfone Membranes for Fuel Cell Applications

  • Chang, Sung-Hyuk;Chung, Sung-Il;Rhim, Ji-Won
    • Korean Membrane Journal
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    • v.5 no.1
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    • pp.18-24
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    • 2003
  • In order to improve the mechanical properties of the sulfonated polysulfone (SPSf) membranes previously synthesized in our laboratory, poly(vinyl alcohol) (PVA) was blended which is well known as the excellent physical and chemical properties. The resulting membranes blended with several molecular weight of PVA varying from 13,000 to 124,000 have been characterized to investigate the effect of PVA molecular weight in terms of ion conductivities, methanol permeabilities, water contents and ion exchange capacities for both heat treated and untreated membranes at 150$^{\circ}C$. The proton conductivity is decreased as the molecular weight of PVA increases. The plain SPSf-6.0 showed the proton conductivity of 0.078 S/cm whereas the blended membrane with M.W. 31,000 PVA indicated 0.04 S/cm. For methanol permeabilities, when PVA is added to SPAf-6.0, methanol crossover is increased because of the gain of the hydrophilicity from 3.4 to 6.5${\times}$10$\^$-6/ $\textrm{cm}^2$/s. For the annealed blended membranes (with M.W. 31,000 PVA), both the methanol corssover and proton conductivity showed very consistent values, about 2.3${\times}$10$\^$-6/ $\textrm{cm}^2$/s and 0.036 S/cm, respectively.

Proton Conductivity and Methanol Permeability of Sulfonated Polysulfone/PPSQ Composite Polymer Electrolyte Membrane (설폰화된 폴리설폰/PPSQ 유-무기 복합 전해질막의 수소이온 전도도 및 메탄올 투과 특성)

  • Kwon Jeongdon;Lee Changjin;Kang Yongku
    • Journal of the Korean Electrochemical Society
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    • v.7 no.2
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    • pp.89-93
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    • 2004
  • Sulfonated polysulfone (SPSF) with poly(phenylmethyl silsesquioxane, PPSQ) composite polymer electrolyte membranes were prepared and their proton conductivity, water uptake and methanol permeability of membranes were characterized. By controlling the ratio of $(CH_3)_3SCI\;and\;CISO_3H$ and reaction time, SPSF with $37\~75\%$ degree of sulfonation were synthesized. The increase of sulfonate groups in the base polymer resulted in the increase of the water uptake in the membranes as well as methanol permeability. Composite membranes were prepared by casting of DMF solution of SPSF and PPSQ. The proton conductivity of the composite membrane at room temperature was $2.8\times10^{-3}\~4.9\times10^{-2}S/cm.$ The increase of PPSQ contents in composite membranes resulted in a decrease in water uptake and methanol permeability. Composite membranes containing $5\%$ PPSQ did not make a significant effect on the proton conductivity nO methanol permeability compared with that of pristine SPSF, but a significant decrease of water uptake was observed.