• Title, Summary, Keyword: Proton conductivity

Search Result 298, Processing Time 0.044 seconds

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
    • The Korean Journal of Chemical Engineering
    • /
    • v.34 no.2
    • /
    • pp.328-339
    • /
    • 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.

Proton Conduction in Nonstoichiometric Σ3 BaZrO3 (210)[001] Tilt Grain Boundary Using Density Functional Theory

  • Kim, Ji-Su;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
    • /
    • v.53 no.3
    • /
    • pp.301-305
    • /
    • 2016
  • We investigate proton conduction in a nonstoichiometric ${\Sigma}3$ $BaZrO_3$ (210)[001] tilt grain boundary using density functional theory (DFT). We employ the space charge layer (SCL) and structural disorder (SD) models with the introduction of protons and oxygen vacancies into the system. The segregation energies of proton and oxygen vacancy are determined as -0.70 and -0.54 eV, respectively. Based on this data, we obtain a Schottky barrier height of 0.52 V and defect concentrations at 600K, in agreement with the reported experimental values. We calculate the energy barrier for proton migration across the grain boundary core as 0.61 eV, from which we derive proton mobility. We also obtain the proton conductivity from the knowledge of proton concentration and mobility. We find that the calculated conductivity of the nonstoichiometric grain boundary is similar to those of the stoichiometric ones in the literature.

Synthesis and Characterization of Sulfonated Polyimide Polymer Electrolyte Membranes

  • Kim, Hyoung-juhn;Morton H. Litt;Nam, Sang-Yong;Shin, Eun-mi
    • Macromolecular research
    • /
    • v.11 no.6
    • /
    • pp.458-466
    • /
    • 2003
  • Several copolyimides have been synthesized with different combinations of comonomers in order to study the relationship between conductivity and water insolubility. m-Phenylenediamine (m-PDA), an angled comonomer, was introduced into the polymer backbone to increase water absorption, and resulted in higher proton conductivity. 2,2-bis(trifluoromethyl)benzidine (TFMB) was used as the comonomer to promote water insolubility. There is a good correlation between the water uptake and conductivity of the polyimides. The copolyimides that had high water uptake also generated high proton conductivity. Those polyimides had good mechanical properties. The copolyimides that have 27 mol% of TFMB and 9 mol% of m-PDA have reasonable conductivities and are insoluble in water at 90$^{\circ}C$, even though they have lower conductivities than those of the homopolymer.

Preparation and Characterization of Nafion Composite Membranes Containing 1-ethyl-3-methylimidazolium Tetracyanoborate

  • Shin, Mun-Sik;Park, Jin-Soo
    • Journal of the Korean Electrochemical Society
    • /
    • v.15 no.1
    • /
    • pp.35-40
    • /
    • 2012
  • The composite membranes using Nafion as matrix and 1-ethyl-3-methylimidazolium tetracyanoborate (EMITCB) as ion-conducting medium in replacement of water were prepared and characterized. The amount of EMITCB in Nafion varied from 30 to 50wt%. The composite membranes are characterized by ion conductivity, thermogravitational analyses (TGA) and small-angle X-ray scattering (SAXS). The composite membranes containing EMITCB of 40wt% showed the maximum ionic conductivity which was ~0.0146 S $cm^{-1}$ at 423.15 K. It is inferred that the decrease in ionic conductivity of all the composite membranes might be due to the decomposition of a tetracyanoboric acid formed in the composite membranes. The results of SAXS indicated that the ionic clusters to conduct proton in the composite membranes were successfully formed. In accordance with the results of ionic conductivity as a function of a reciprocal temperature, SAXS showed a proportional decrease in scattering maximum $q_{max}$ as the amount of EMITCB increases in the composite membranes, which results in the increase in ionomer cluster size. The TGA showed no significant decomposition of the ionic liquid as well as the composite membranes in the range of operating temperature ($120-150^{\circ}C$) of high temperature proton exchange membrane fuel cells (HTPEMFC). As a result, EMITCB is able to play an important role in transferring proton in the composite membranes at elevated temperatures with no external humidification for proton exchange membrane fuel cells.

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
    • /
    • v.12 no.4
    • /
    • pp.413-421
    • /
    • 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 Characterization of Proton Conductive Phosphosilicate Membranes Based on Inorganic-Organic Hybrid Materials

  • Huang, Sheng-Jian;Lee, Hoi-Kwan;Kang, Won-Ho
    • Bulletin of the Korean Chemical Society
    • /
    • v.26 no.2
    • /
    • pp.241-247
    • /
    • 2005
  • A series of proton conductive inorganic-organic hybrid membranes doped with phosphoric acid ($H_3PO_4$) and/or triethylphosphate (PO(OEt)$_3$) have been prepared by sol-gel process with 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0 ${\times}$ $10^{-3}$ S/cm with composition of 50TEOS-30GPTMS-20APTES-50$H_3PO_4$ was obtained at 120 ${^{\circ}C}$ under 50% relative humidity. Thermal stability of membrane was significantly enhanced by the presence of SiO$_2$ framework up to 250 ${^{\circ}C}$. XRD revealed that the gels are amorphous. IR spectra showed a good complexation of $H_3PO_4$ in the matrix. The conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in concentration of defected site in hybrid matrix. The effect of PO(OEt)$_3$, humidifying time, and heat-treatment were also investigated. PO(OEt)$_3$ had no improvement on conductivity and conductivity increased with humidifying time, however, decreased with heating temperature.

Electrical Conduction in $SrZr_{0.95}Y_{0.05}O_{2.975}$ Ceramics

  • Baek, Hyun-Deok;Noh, Jin-Hyo
    • The Korean Journal of Ceramics
    • /
    • v.5 no.3
    • /
    • pp.288-295
    • /
    • 1999
  • Partial conductivities contributed by electron holes, oxygen ions, and protons were caluclated in $SrZr_{0.95}Y_{0.05}O_{2.975}$, using the reported formulae derived from the defect chemistry of HTPCs. Required parameters were obtained from the graphical analysis of total conductivity variation against partial pressure of water vapor and oxygen. Predicted overall conductivities showed a reasonable agreement with experimental measurements. The conductivity of the material showed a linear increase with square root of the water vapor pressure. This increase was due to proton conduction in an almost pure ionic conductivity. The calculation of partial conductivities at $800^{\circ}C$ resulted in an almost pure ionic conductivity at $P_{02}=10^{-10}$ atm and a predominant hole conductivity at $P_{02}=10^{-10}$ atm. Pure proton conduction was not expected at this temperature, contrary to the earlier reports. Discussions were made in relation with reported thermodynamic data and defect structure of the material. It was shown that from the total conductivity dependence on water vapor pressure, the pure ionic conductivity at low oxygen partial pressures could be separated into protonic and oxygen ionic conductivity in $ZrO_2$-based HTPCs.

  • PDF

Polymeric Gel Electrolytes for Electric Double Layer Capacitors (전기이중층 캐패시터에 관한 폴리머 겔 전해액)

  • Morita, Masayuki;Qiao, Jin-Li
    • Journal of the Korean Electrochemical Society
    • /
    • v.6 no.2
    • /
    • pp.141-144
    • /
    • 2003
  • Proton conducting polymeric gels as the electrolytes of electrochemical capacitors have been prepared by two different methods: 1) swelling a polymethacrylate-based polymer matrix in aqueous solutions of inorganic and organic acids, and 2) polymerizing complexes of anhydrous acids and prepolymers with organic plasticizer. The FT-IR spectra strongly suggest that the carbonyl groups in the polymer matrix interact with protons from the doped acids. High ionic (proton) conductivity in the range of $6\times10^{-4}-4\times10^{-2}\;S\;cm^{-1}$ was obtained at room temperature for the aqueous gels. The non-aqueous polymer complexes showed rather low ionic conductivity, but it was about $10^{-3}\;S\;cm^{-1}\;at\;70^{\circ}C$ for the $H_3PO_4$ doped polymer electrolyte. The mechanisms of ion (proton) conduction in the polymeric systems are discussed.

Anhydrous Proton Conducting Polymer Electrolytes Based on Poly(phosphonic acid)s and Oligomeric Triazole Compounds

  • Song, Myeong-Soo;Lee, Sung-Il;Bingoel Bahar;Meyer Wolfgang H.;Yoon, Do-Y.
    • Proceedings of the Polymer Society of Korea Conference
    • /
    • /
    • pp.272-272
    • /
    • 2006
  • In recent years, water-free polymer electrolyte membranes are attracting serious attention due to the possibility of the fuel cell operation at intermediate temperatures ($100{\sim}200^{\circ}C$). It was reported that phosphonic acids have proton conductivity under anhydrous conditions and in particular, relatively high proton conductivity could be obtained from the composite materials with heterocycles such as imidazole, pyrazole, etc. In this work, styrene based polymers, poly((4-vinylbenzyloxy)alkylphosphonic acid), which have phophonic acid group at the end of alkyl chain was synthesized. These polymers were analyzed in terms of thermal stability and proton conductivity. Additionally, cyclic oligosiloxanes tethered with triazole were prepared and analyzed.

  • PDF

Transport Properties of Polymer Blend Membranes of Sulfonated and Nonsulfonated Polysulfones for Direct Methanol Fuel Cell Application

  • Kim, Dong-Hwee;Kim, Sung-Chul
    • Macromolecular research
    • /
    • v.16 no.5
    • /
    • pp.457-466
    • /
    • 2008
  • The relation between the phase separated morphologies and their transport properties in the polymer blend membrane for direct methanol fuel cell application was studied. In order to enhance the proton conductivity and reduce the methanol crossover, sulfonated poly(arylene ether sulfone) copolymer, with a sulfonation of 60 mol% (sPAES-60), was blended with nonsulfonated poly(ether sulfone) copolymer (RH-2000, Solvay). Various morphologies were obtained by varying the drying condition and the concentration of the casting solution (10, 15, 20 wt%). The transport properties of proton and methanol molecule through the polymer blend membranes were studied according to the absorbed water. AC impedance spectroscopy was used to measure the proton conductivity and a liquid permeability measuring instrument was designed to measure the methanol permeability. The state of water in the blend membranes was confirmed by differential scanning calorimetry and was used to correlate the morphology of the membrane with the membrane transport properties.