ZrO2–Nafion composite membranes for polymer electrolyte fuel cells (PEFCs) at intermediate temperature (original) (raw)
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Journal of Membrane Science, 2004
The physio-chemical properties of Nafion 115 and a composite Nafion 115/Zirconium Phosphate (25wt%) membranes are compared. The composite membrane takes up more water than Nafion at the same water activity. However, the proton conductivity of the composite membrane is slightly less than that for Nafion 115. Small angle X-ray scattering shows the hydrophilic phase domains in the composite membrane are spaced further apart than in Nafion 115, and the composite membrane shows less restructuring with water uptake. Despite the lower proton conductivity of the composite membranes they display better fuel cell performance than Nafion 115 when the fuel cell is operated under-humidified. It is suggested that the composite membrane has a greater rigidity that accounts for its improved fuel cell performance.
Materials Science for Energy Technologies, 2018
In this work, Nafion ionomer was prepared by a dissolution method in high pressuretemperature autoclave reactor using Nafion membrane sources. Zirconia nanoparticles were synthesized by the microwave assisted gel combustion method. The synthesized nanoparticles were characterized by XRD and FESEM, and then added to the Nafion solution to prepare recast Nafion nanocomposite membranes (R-Nafion/ZrO 2) with different loading of ZrO 2 nanoparticles. Membranes were prepared by recasting method and characterized in terms of water uptake, dimensional stability, ionic conductivity, chemical stability (Fenton test), tensile strength, and scanning electron microscope (SEM) techniques. The obtained results for nanocomposite membranes were compared to the filler-free recast Nafion and commercial Nafion membranes. The nanocomposite membranes showed higher water uptake, mechanical and oxidative stabilities and the hygroscopic zirconia nanoparticles resulted higher proton conductivity of nanocomposite membranes at different temperatures in comparison with pure recast Nafion membrane. The prepared membranes showed defect free, dense microstructure, and good dispersion of nanoparticles in the membranes' matrix. The results illustrated the prepared nanocomposite membranes have good physicochemical and electrochemical properties for PEMFC applications.
Thermal Properties and Conductivity of Nafion-Zirconia Composite Membrane
Malaysian Journal of Analytical Science, 2016
The application of composite membranes for high temperature polymer electrolyte membrane fuel cell has attracted interests. Nafion-metal dioxide composite membranes are considered among the research niche. In this study, Nafion membranes and Nafion-zirconia composite membranes with 1, 3 and 5 wt. % of hydrous zirconia were prepared accordingly. All membranes were characterized by quantitative analysis techniques such as thermogravimetry analyse, diffraction scanning calorimetry and Fourier transform infrared. All composite membranes showed high glass transition temperatures and improved water retention properties, compared to the Nafion membrane. The composite membrane with 3 wt. % of zirconia showed the highest thermal resistance at 90°C.
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.
Properties and fuel cell performance of a Nafion-based, sulfated zirconia-added, composite membrane
Journal of Power Sources, 2008
The effect of an acidic inorganic additive, i.e. sulfated zirconia, on Nafion-based polymer electrolytes is evaluated by comparing the properties in terms of conductivity and fuel cell performance of a composite sulfated zirconia-added Nafion membrane with those of an additive-free Nafion membrane. The peculiar surface properties of the selected filler promote a higher hydration level and a higher conductivity for the composite membrane under unsaturated conditions, i.e. at 20% RH. Tests on H 2-air fully humidified cells, monitored at 70 • C and at atmospheric pressure, reveal small differences when passing from a plain Nafion to a composite Nafion/sulfated zirconia membrane as electrolyte. However, remarkably great improvements are observed for the composite membrane-based cell when the comparison tests are run at low relative humidity and high temperature, this outlining the beneficial role of the sulfated zirconia additive.
Zirconia Based / Nafion Nanocomposite Membranes for Fuel Cell Applications
2014
The nanoparticles of zirconium oxide, sulfated zirconia and phosphated zirconia were used to modify Nafion membrane in order to improve the water retention, thermal stability, proton conductivity and methanol permeability. The modified Nafion nanocomposite membranes were used for high temperature fuel cell between 120-140°C. The inorganic nanoparticles were incorporated within Nafion by recast, swelling-impregnation and ion exchange methods. The inorganic nanoparticles were characterized by XRD, BET, FTIR, TGA, DSC, SEM and TEM, while nanocomposite membranes were characterized for water uptake, ion exchange capacity, methanol permeability, and proton conductivity. Pristine ZrO2, sulfated and phosphated ZrO2 were successfully synthesized. The particle sizes ranged from 10 nm to 30 nm, with good dispersity in the membrane. The conductivity of the Nafion / 5% sulfated zirconia membrane exceeded 0.103 S/cm at room temperature and has the highest water uptake of 35%. On the other hand, N...
Nafion ® 115/zirconium phosphate composite membranes for operation of PEMFCs above 100 °C
Electrochimica Acta, 2002
Composite Nafion/zirconium phosphate membranes were investigated for high temperature operation of proton exchange membrane fuel cells (PEMFCs). The composite membranes were prepared via impregnation of Nafion films (either commercial Nafion 115 or recast Nafion) with zirconyl chloride and 1 M phosphoric acid at 80°C. An MEA employing a composite membrane prepared starting from commercial Nafion 115 gave a H 2 /O 2 PEMFC performance of about 1000 mA/cm 2 at 0.45 V at a temperature of 130°C and a pressure of 3 bar; this result compares very favorably with the performance of an MEA based on commercial unmodified Nafion, which gave only 250 mA/cm 2 at 0.45 V when operated under the same conditions of temperature and pressure. Similar experiments performed with recast Nafion and recast Nafion/zirconium phosphate composites confirmed an analogous improvement of performance of the composite membranes over the unimpregnated ones. In this case, the composite recast Nafion/zirconium phosphate gave about 1500 mA/cm 2 at 0.45 V at a temperature of 130°C and a pressure of 3 bar. The composite membranes showed stable behavior during time when maintained at 130°C, while irreversible degradation affected Nafion under the same conditions.
Journal of Membrane Science, 2015
We report a high performance and durable electrolyte membrane operated in polymer electrolyte membrane fuel cells under low relative humidity (RH). This was accomplished by incorporating water retaining mesoporous zirconium oxide (ZrO 1.95) nanotubes (ZrNT) in a perfluorosulfonic acid (Nafion) membrane. Porous ZrNT with average diameters of 90 nm was synthesized by pyrolysing electrospun zirconium precursor embedded polymer fibers at 600 o C under an air atmosphere. The superior water retention ability and the tubular morphology of the ZrNT fillers resulted in facile water diffusion though the membrane, leading to a significant improvement in membrane proton conductivity under both fully humid and dry conditions. Compared to a commercial membrane (Nafion, NRE-212) operated under 50, and 100 % RH at 80 o C, the Nafion-ZrNT membrane exhibited 2.7, and 1.2 times higher power density at 0.6 V, respectively. Under dry condition (18% RH at 80 o C), the Nafion-ZrNT membrane exhibited 3.1 times higher maximum power density than the NRE-212 membrane. In addition, the Nafion-ZrNT membrane also exhibited durable operation for 200 h under 18% RH at 80 o C. The remarkably high performance of the Nafion-ZrNT composite membrane was mainly attributed to the reduction of ohmic resistance by incorporating the mesoporous hygroscopic ZrO 1.95 nanotubes.
Nafion/Analcime and Nafion/Faujasite composite membranes for polymer electrolyte membrane fuel cells
Chemical Engineering Research & Design, 2010
The Nafion/zeolite composite membranes were synthesized for polymer electrolyte fuel cells (PEMFCs) by adding zeolite in the matrix of Nafion polymer. Two kinds of zeolites, Analcime and Faujasite, having different Si/Al ratio were used. The physico-chemical properties of the composite membranes such as water uptake, ion-exchange capacity, hydrogen permeability, and proton conductivity were determined. The fabricated composite membranes showed the significant improvement of all tested properties compared to that of pure Nafion membrane. The maximum proton conductivity of 0.4373 S cm−1 was obtained from Nafion/Analcime (15%) at 80 °C which was 6.8 times of pure Nafion (0.0642 S cm−1 at 80 °C). Conclusively, Analcime exhibited higher improvement than Faujasite.