Composite Nafion-CaTiO3-δ Membranes as Electrolyte Component for PEM Fuel Cells (original) (raw)
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Polymers, 2019
Nafion composite membranes, containing different amounts of mesoporous sulfated titanium oxide (TiO2-SO4) were prepared by solvent-casting and tested in proton exchange membrane fuel cells (PEMFCs), operating at very low humidification levels. The TiO2-SO4 additive was originally synthesized by a sol-gel method and characterized through x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and ion exchange capacity (IEC). Peculiar properties of the composite membranes, such as the thermal transitions and ion exchange capacity, were investigated and here discussed. When used as an electrolyte in the fuel cell, the composite membrane guaranteed an improvement with respect to bare Nafion systems at 30% relative humidity and 110 °C, exhibiting higher power and current densities.
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.
Journal of Power Sources, 2002
Composite polymer electrolyte membranes were prepared by impregnating Nafion solution into the porous expanded PTFE (ePTFE) films as a substrate and their single cell performance, gas permeability, water flux, and water uptake were investigated. Although the nitrogen permeability of the composite membrane was higher than that of Nafion 112, there was not the serious cross-over of gases to diminish cell performance and it was seen that the cell performance could be improved by reduced thickness of the composite membrane. It was also seen that water uptake and water flux of the composite membrane were dependent on the Nafion loading amount on the substrate and, therefore, the thickness of the membrane. The water uptake as well as the water flux of the composite membrane increased as the Nafion loading amount increased and the increase rate of water uptake with temperature for the composite membranes was found to be larger than Nafion 112. #
Membranes, 2019
A composite membrane based on a Nafion polymer matrix incorporating a non-stoichiometric calcium titanium oxide (CaTiO3−δ) additive was synthesized and characterized by means of thermal analysis, dynamic mechanical analysis, and broadband dielectric spectroscopy at different filler contents; namely two concentrations of 5 and 10 wt.% of the CaTiO3−δ additive, with respect to the dry Nafion content, were considered. The membrane with the lower amount of additive displayed the highest water affinity and the highest conductivity, indicating that a too-high dose of additive can be detrimental for these particular properties. The mechanical properties of the composite membranes are similar to those of the plain Nafion membrane and are even slightly improved by the filler addition. These findings indicate that perovskite oxides can be useful as a water-retention and reinforcing additive in low-humidity proton-exchange membranes.
18th World Hydrogen Energy Conference, 2010
In the present study, Nafion/Titanium dioxide (TiO 2) nanocomposite membranes for use in proton exchange membrane fuel cells (PEMFC) were investigated. Nafion/TiO 2 membranes were prepared using the recasting procedure. The composite membranes have been characterized by thermal analysis, XRD, SEM, proton conductivity measurements and single cell performance. Thermal analysis results showed that the composite membranes have good thermal properties. The introduction of the inorganic filler supplies the composite membrane with a good thermal resistance. The physico-chemical properties studied by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques have proved the uniform and homogeneous distribution of TiO 2 and the consequent enhancement of crystalline character of these membranes. The energy dispersive spectra (EDS) analysis indicated that the distribution of Ti element on the surface of the composite membrane was uniform. Performances of fabricated Membrane electrode assembly (MEA)'s measured via the PEMFC test station built at METU Fuel Cell Technology Laboratory. A single cell with a 5 cm 2 active area was used in the experiments. These results should be conducive to the preparation of membranes suitable for PEMFC. We believe that Nafion/TiO 2 nano composite membranes have good prospects for use in PEMFC.
International Journal of Hydrogen Energy, 2012
Nafion Polymer electrolyte membrane fuel cells Dynamical mechanic analyses Vibrational spectroscopy Fabrication and testing of membrane-electrode assemblies a b s t r a c t In this report, three hybrid inorganic-organic proton-conducting membranes based on a novel fluorinated titania labeled TiO 2 F dispersed in Nafion were prepared. The mass fraction of TiO 2 F nanofiller ranged between 0.05 and 0.15. The water uptake and the proton exchange capacity of the membranes were determined; the membranes were further characterized by TG, DMA and FT-IR ATR investigations. Finally, the hybrid membranes were used in the fabrication of membrane-electrode assemblies (MEAs), which were tested in operating conditions as a function of the back pressure and of the hydration degree of the reagents streams. It was demonstrated that, with respect to pristine recast Nafion, at 25%RH the MEA fabricated with the membrane including a mass fraction of TiO 2 F equal to 0.10 yielded a higher maximum power density (0.206 W cm À2 vs. 0.121 W cm À2 ). Finally, it was proposed a coherent structural model of this family of hybrid membranes accounting for both the properties determined from "ex-situ" characterizations and for the performance obtained from measurements in a single fuel cell in operating conditions.
2008
Nafion-Silica oxide (SiO2)-Phosphotungstic acid (PWA) composite membrane have been synthesized using solution phase sol-gel method. The effect of the weight ratio of Nafion:SiO2:PWA to the electrochemical properties of composite membrane when applies as electrolyte in the PEMFC was investigated using Fuel Cell Test System (FCTS) at temperature of range of 80 – 90 oC and 40% relative humidity (RH). The weight ratio of the composite membrane samples varied in the range of 100:2.88:1.15, 100:4.33:1.73 and 100:5.76:2.30 and designated as NS10W, NS15W and NS20W, respectively. The aim of the experiment was to insert the inorganic hygroscopic and high conductivity filler like PWA and SiO2 in the Nafion matrix to order to improve the water retention, proton conductivity (σ), hydrogen crossover (β), and thermal stability in addition to increase PEMFC performance at elevated temperature and low RH condition. The result showed when appropriately embeded in the Nafion cluster, the hydrated PWA ...
Electrochimica Acta, 2000
Several new cation exchange membranes of different thicknesses (15-500 mm) based on a Nafion ® solution and silicotungstic acid with and without thiophene (named NASTATH and NASTA respectively) were synthesized by a simple chemical route for PEM fuel-cell applications. The optimum parameters for the preparation of the membranes have been determined: 10 ml of 5% of the Nafion ® 117 solution was reduced by 50% and mixed with 10 − 3 -10 − 5 M-STA to produce a NASTA membrane. If liquid thiophene (0.5% by volume) is added to the above solution, a NASTATH membrane is produced. The water uptake and ionic conductivity of NASTA and NASTATH were compared with those of Nafion ® 117. The effect of membrane thickness and the concentrations of STA and thiophene used during the preparation of NASTA and NASTATH on their water uptake and ionic conductivity were determined. It was shown that the water uptake of the NASTA membrane (60%) was significantly better than that of Nafion ® 117 (27%), while the water uptake of NASTATH (40%) was higher than that of Nafion ® 117 (27%). The ionic conductivity of both the NASTA (10.10 × 10 − 2 V − 1 cm − 1 ) and the NASTATH (9.5×10 − 2 V − 1 cm − 1 ) was found to be significantly higher than that of the Nafion ® 117 (1.23 ×10 − 2 V − 1 cm − 1 ). The membrane performances were also determined by chemical stability studies. The membranes fabricated with Nafion ® and silicotungstic acid with and without thiophene still exhibited good mechanical strength and stability after they had been dipped in an acid or a basic medium for at least 10 months. The voltage-current characteristics of solid polymer electrolyte fuel cells were determined for Nafion ® 117, NASTA and NASTATH based membranes. The fuel cell parameters were correlated to the membrane water uptake and ionic conductivity. The current density at 0.600 V of the solid polymer electrolyte fuel cells (SPEFCs) based on NASTATH (810 mA cm − 2 ) membranes was higher than that of SPEFCs based on Nafion ® 117 (640 mA cm − 2 ). It was shown that the better fuel cell parameters were not obtained with the modified membranes having the higher water uptake.
2008
Investigation of the single cell Proton Exchange Membrane Fuel Cell (SCPEMFC) using a series of Nafion-SiO2-PWA composite membranes as electrolyte have been carried out using the Arbin Fuel Cell Test System (FCTS). PEMFC performance and proton conductivity of the composite membrane have been determined over a temperature range of 30-90 o C at pressure 1-1.7 atm at 40% RH. Analysis with FCTS showed that higher current density was yielded by composite membrane (82 mAcm -2 at 0.6 V for NS15W) than with the Nafion membrane (30 mAcm -2 at 0.2 V) at 90 o C. Hence the composite is potentially a good candidate to substitute Nafion membrane especially for the electrolyte of PEMFC operating at higher temperature range and lower RH.
Fuel and Energy Abstracts
Nafion is the most widely accepted and commercialized membrane for polymer electrolyte membrane fuel cells owing to its high proton conductivity, mechanical stability and cell performance under humidified conditions at low temperature. However, the performance of the membrane deteriorates rapidly above 80 • C. In this work, Laponite XLS, a synthetic grade of peptized Laponite clay, is used as inorganic filler to prepare Nafion-clay nanocomposite membranes using solution mixing technique. The presence of sodium pyrophosphate (Na 4 P 2 O 7 ) on the surface of Laponite XLS holds the key towards the improvement in proton conductivity of the nanocomposites compared to the virgin Nafion. Incorporation of acid-activated Laponite to Nafion further improves the mechanical property, thermal stability, water uptake and proton conductivity of the resulting nanocomposite due to the presence of in situ generated H 3 PO 4 on the surface of acid-activated Laponite. The proton conductivity of the nanocomposite membrane containing 3 wt% acid-activated Laponite is found to be 270.2 mS/cm compared to 136.2 mS/cm for the virgin Nafion at 110 • C.