The Ionic Conductivity of a Nafion® 1100 Series of Proton-exchange Membranes Re-cast from Butan-1-ol and Propan-2-ol (original) (raw)
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Characteristics of the Nafion®-impregnated polycarbonate composite membranes for PEMFCs
Electrochimica Acta, 2004
In this work, polycarbonate composite membranes were prepared for proton exchange membrane fuel cells (PEMFCs). In the preparation of membranes, a small amount of poly(ethylene glycol) (PEG) was blended with polycarbonate (PC) solution and then cast to make membranes. PEG contained in the membrane was removed by the high solubility of supercritical CO 2 to afford porosity in the membrane. Then, porous PC membranes were soaked in Nafion ® solution to yield the PC/Nafion ® composite membranes. The PC composite membrane had lower ion conductivity but higher conductance than Nafion ® .
International Journal of Hydrogen Energy, 2009
Nafion membranes modified with silica and silica sulfuric acid are fabricated for the elevated temperature and lower humidity operation of proton-exchange membrane fuel cells. An incorporation of silica sulfuric acid promotes the amorphous phase which in turn influences the segmental motion of polymeric chains. By the endeavor of sulfonic acid moieties, ion channels are extended and facilitate the high ionic diffusion. With the hygroscopic effort, high water molecules retention is favored which provokes the self humidification of Nafion membrane. The electrochemical properties of the composite membranes are varied in terms of the permeation effect of different sized silica particles in to the viable channels of Nafion membrane. Though higher electrochemical properties are obtained for the Nafion-silica sulfuric acid composite membranes, a balance between the electrochemical and physical properties is also highly maintained as that of bare Nafion membrane. The inclusion of silica sulfuric acid provides more sulfonic acid functional groups for the conscription of electrochemical properties and ceramic property of the material strengthens the perfluorinated polymer back bone which collectively extends the fuel cell performance of composite Nafion membranes and influences its potential application.
Nafion/Acid Functionalized Mesoporous Silica Nanocomposite Membrane for High Temperature PEMFCs
2000
This study reports the synthesis and the characterization of proton conducting composite membranes prepared by dispersing in Nafion matrix with highly acid functionalized mesoporous silica (KIT-6). Nafion/KIT-6 composite membranes were studied for operation in hydrogen/oxygen polymer electrolyte membrane fuel cells (PEMFC) at 120 °C with different relative humidities (72%RH and 100%RH). The Nafion/KIT-6 composite membrane demonstrated little improved fuel cell performance to that of the Nafion membrane at 100% relative humidity (RH), however, it was much higher at low RH (72%). These results suggest that this new type of Nafion composite membrane may be successfully used as an improved proton exchange membrane in high temperature PEMFC.
International Journal of Hydrogen Energy, 2012
Polymer electrolyte membrane fuel cells Water uptake Thermogravimetric measurements Fabrication and testing of membraneelectrode assemblies a b s t r a c t This work reports the preparation, characterization and test in a single fuel cell of two families of hybrid inorganic-organic proton-conducting membranes, each based on Nafion and a different "core-shell" nanofiller. Nanofillers, based on either a ZrO 2 "core" covered with a HfO 2 "shell" (ZrHf) or a HfO 2 "core" solvated by a "shell" of SiO 2 nanoparticles (SiHf), are considered. The two families of membranes are labelled [Nafion/(ZrHf) x ] and [Nafion/ (SiHf) x ], respectively. The morphology of the nanofillers is investigated with high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX) and electron diffraction (ED) measurements. The mass fractions of nanofiller x used for both families are 0.05, 0.10 or 0.15. The proton exchange capacity (PEC) and the water uptake (WU) of the hybrid membranes are determined. The thermal stability is investigated by high-resolution thermogravimetric measurements (TGA). Each membrane is used in the fabrication of a membrane-electrode assembly (MEA) that is tested in single-cell configuration under operating conditions. The polarization curves are determined by varying the activity of the water vapour (a H2O ) and the back pressure of the reagent streams. A coherent model is proposed to correlate the water uptake and proton conduction of the hybrid membranes with the microscopic interactions between the Nafion host polymer and the particles of the different "coreeshell" nanofillers.
Conductivity in zeolite–polymer composite membranes for PEMFCs
Journal of Power Sources, 2007
Structured materials, such as zeolites can be candidates to be used as electrolytes in proton exchange membrane fuel cells (PEMFC) to substitute polymeric membranes, taking advantage of their higher chemical and thermal stability and their specific adsorption properties. The possibility to work at temperatures of nearly 150 • C would make easy the selection of the fuel, decreasing the influence of CO in the catalyst poisoning, and it would also improve the kinetics of the electrochemical reactions involved. In this work, four zeolites and related materials have been studied: mordenite, NaA zeolite, umbite and ETS-10. In special, the influence of relative humidity and temperature have been carefully explored. A conductivity cell was designed and built to measure in cross direction, by using the electrochemical impedance spectroscopy. The experimental system was validated using Nafion ® as a reference material by comparing the results with bibliography data. Samples were prepared by pressing the zeolite powders, with size of 1 m on average, using polymer PVDF (10 wt.%) as a binder. The results here obtained, in spite of not reaching the absolute values of the Nafion ® ones, show a lower effect of the dehydration phenomenon on the conduction performance in the temperature range studied (from room temperature to 150 • C). This increase of the operation temperature range would give important advantages to the PEMFC. ETS-10 sample shows the best behaviour with respect to conductivity exhibiting an activation energy value comparable with reported for Nafion ® membrane.