Nafion-TiO2 composite DMFC membranes: Physico-chemical properties of the filier versus electrochemical performance

TiO2 nanometric powders were prepared via a sol-gel procedure and calcined at various temperatures to obtain different surface and bulk properties. The calcined powders were used as fillers in composite Nafion membranes for application in high temperature direct methanol fuel cells (DMFCs). The powder physico-chemical properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and pH measurements. The observed characteristics were correlated to the DMFC electrochemical behaviour. Analysis of the high temperature conductivity and DMFC performance reveals a significant influence of the surface characteristics of the ceramic oxide, such as oxygen functional groups and surface area, on the membrane electrochemical behaviour. A maximum DMFC power density of 350 mW cm-2 was achieved under oxygen feed at 145°C in a pressurized DMFC (2.5 bar, anode and cathode) equipped with TiO2 nano-particles based composite membranes. © 2004 Elsevier Ltd. All rights reserved

Influence of TiO2 nanometric filler on the behaviour of a composite membrane for applications in direct methanol fuel cells

Composite Nafion membranes containing various amounts of TiO2 (3 wt%, 5 wt% and 10 wt%) were investigated for operation in high temperature Direct Methanol Fuel Cells (DMFCs). Maximum power density of 350 mW cm -2 was achieved in the presence of oxygen feed at 145°C for the composite membranes containing 3-5 wt% TiO2; whereas, the maximum power density with air feed was about 210 mW cm-2. Moreover, an investigation of the influence of titanium oxide particle size on the electrochemical behaviour of the composite membranes for high temperature operation has been carried out. The DMFC performance increases as the mean particle size of the TiO2 filler decreases. This indicates an influence of the filler morphology on the electrochemical properties of the composite membranes. © J. New. Mat. Electrochem. Systems

PEO based polymer electrolyte lithium-ion battery

Nanocomposite ZrO2-added PEO-based solid polymer electrolytes and nanocomposite Ag-added LiFePO4 cathodes have been utilized to realize all solid state metallic lithium batteries. In this work the electrochemical properties of these materials will be illustrated and discussed. © 2003 Elsevier Ltd. All rights reserved

Metallic-lithium, LiFePO4-based polymer battery using PEO-ZrO2 nanocomposite polymer electrolyte

A study of the electrochemical properties of a PEO-based polymer electrolyte with nanometric ZrO2 as ceramic filler has been carried out in order to confirm an earlier reported model dealing with the role of ceramic fillers within PEO-based polymer electrolytes as components that enhance such properties as conductivity, lithium transference number, compatibility with lithium metal electrodes and cyclability. A prototype of a lithium polymer battery, based on a membrane made from a nanocomposite polymer electrolyte doped with ZrO2, utilizing LiFePO4+1% Ag as cathode, has been assembled and galvanostatically cycled, resulting in excellent performance at temperatures ranging from 100degreesC to 60degreesC (close to the crystallization temperature of PEO)

Influence of TiO2 nanometric filler on the behaviour of a composite membrane for applications in direct methanol fuel cells

Composite Nafion membranes containing various amounts of TiO2 (3 wt%, 5 wt% and 10 wt%) were investigated for operation in high temperature Direct Methanol Fuel Cells (DMFCs). Maximum power density of 350 mW cm -2 was achieved in the presence of oxygen feed at 145°C for the composite membranes containing 3-5 wt% TiO2; whereas, the maximum power density with air feed was about 210 mW cm-2. Moreover, an investigation of the influence of titanium oxide particle size on the electrochemical behaviour of the composite membranes for high temperature operation has been carried out. The DMFC performance increases as the mean particle size of the TiO2 filler decreases. This indicates an influence of the filler morphology on the electrochemical properties of the composite membranes. © J. New. Mat. Electrochem. Systems

Composition dependent physical properties of poly[(vinylidene fluoride)-co-trifluoroethylene] - poly(ethylene oxide) blends

Polymer blends based on poly(vinylidene fluoride – co – trifluoroethylene) copolymers, P(VDF-TrFE), and poly(ethylene oxide), PEO, with varying compositions have been prepared by solvent casting. In this way, P(VDF-TrFE) crystallizes from the solution while solvent evaporates, while PEO crystallizes from the melt during cooling to room temperature. The surface morphology of the polymer blends indicates the transition from the fibrillar microstructure typical of PVDF-TrFE to the spherulite structure characteristic of PEO. The vibration modes characteristics of P(VDF-TrFE) are not influenced by the presence of PEO in the polymer blend. Confinement of PEO in the P(VDF-TrFE) phase change the conformation of PEO from trans to helix, increasing this transformation for increasing P(VDF-TrFE) content in the polymer blends. Sequential crystallization of the two polymers produce separated amorphous phases whose independent cooperative conformational motions are revealed by two main dynamic-mechanical relaxations. No chemical interaction seems to exist between the polymers within the blend.Abstract: Polymer blends based on poly(vinylidene fluoride – co – trifluoroethylene) copolymers, P(VDF-TrFE), and poly(ethylene oxide), PEO, with varying compositions have been prepared by solvent casting. In this way, P(VDF-TrFE) crystallizes from the solution while solvent evaporates, while PEO crystallizes from the melt during cooling to room temperature. The surface morphology of the polymer blends indicates the transition from the fibrillar microstructure typical of PVDF-TrFE to the spherulite structure characteristic of PEO. The vibration modes characteristics of P(VDF-TrFE) are not influenced by the presence of PEO in the polymer blend. Confinement of PEO in the P(VDF-TrFE) phase change the conformation of PEO from trans to helix, increasing this transformation for increasing P(VDF-TrFE) content in the polymer blends. Sequential crystallization of the two polymers produce separated amorphous phases whose independent cooperative conformational motions are revealed by two main dynamic-mechanical relaxations. No chemical interaction seems to exist between the polymers within the blend