Nafion–Titanate Nanotube Composite Membranes for PEMFC Operating at High Temperature (original) (raw)
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ECS Transactions, 2007
Nafion-trititanate nanotubes composites were investigated as electrolytes for proton exchange membrane fuel cells (PEMFC) operating at high temperatures (T). With the addition of 5-15 wt.% of nanotubes to the ionomer, PEMFC performance can be significantly sustained for T up to 130 {degree sign}C. This behavior reflects a competing effect between an increase in water uptake due to the extremely large surface area of the nanotubes and a decrease in proton conductivity of the composites.
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.
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 ...
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.
Nafion/PTFE/silicate membranes for high-temperature proton exchange membrane fuel cells
International journal of …, 2008
Fuel cell performance of membrane electrode assemblies (MEAs) prepared from poly (tetrafluoroethylene)/Nafion/silicate (PNS) membrane and Nafion-112 membrane were investigated. Due to the low conductivity of PTFE and silicate, PNS had a higher proton resistance than Nafion-112. However, in this work we show that PNS performs better than Nafion-112 for a high current density i4500 mA=cm 2 operation with a low inlet gas humidity. As the PEMFCs were operated at 60 C with 100% RH, the results showed the maximum power density ðPD max Þ of PNS was: PD max ¼ 717 mW=cm 2 at i ¼ 1452 mA=cm 2 with both H 2 and O 2 flow rates of 300 ml/min, and PD max ¼ 1042 mW=cm 2 at i ¼ 2785 mA=cm 2 with H 2 flow rate of 360 ml/min and O 2 flow rate of 600 ml/min, which were much higher than the PD max ¼ 4677 mW=cm 2 at i ¼ 1130 mA=cm 2 of Nafion-112 with both H 2 and O 2 flow rates of 300 ml/min. The PD max of PNS was: 700 mW=cm 2 , 656 mW=cm 2 , and 577 mW=cm 2 at i ¼ 1400 mA=cm 2 as the operating temperature and inlet gas humidity were set at 90 C with 67.7% RH, 100 C with 46.8% RH, and 110 C with 33.1% RH, respectively. However, no output power was detected for Nafion-112 MEA when the cell was operated at a temperature higher than 90 C and an inlet gas humidity lower than 67.7% RH. The high PEMFC performance of PNS at high current density and low humidity is attributed to the presence of silicate in the PNS membrane, which enhances water uptake and reduces electro-osmosis water loss at a high current density.
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. #
Thermal properties of Nafion–TiO 2 composite electrolytes for PEM fuel cell
Journal of Thermal Analysis and Calorimetry, 2009
Thermal analysis has been used to evaluate the stability, glass transition, and water retention of Nafion based polymer–ceramic electrolytes. These electrolytes are envisioned as promising replacement of Nafion in fuel cells operating above 100 °C. The polymeric matrix prepared by casting exhibits lower crystallinity than the extruded Nafion, a feature that affects the water absorption properties. The addition of titania-based nanotubes and nanoparticles to the polymer has enhanced the water retention at high temperatures (~130 °C) and the glass transition temperature, respectively. Such results are important for the design of composite electrolytes for the operation of fuel cells at high temperatures.
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
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.