Synthesis, Structure, and Reactions of Poly(ethylene oxide)/V₂O₅ Intercalative Nanocomposites

Abstract

The intercalation of poly(ethylene oxide) (PEO) in layered V 2 O 5 xerogel and the structural and physicochemical characterization of the products is reported. The synthesis of PEO/ V 2 O 5 nanocomposites is achieved by simply mixing aqueous solutions of PEO with aqueous V 2 O 5 gels followed by slow water evaporation. Several different phases of PEO/V 2 O 5 composites can be obtained by varying the component ratios. The interlayer distance of (PEO) x V 2 O 5 ‚nH 2 O varies from 13.2 Å, at x ) 0.5, to 16.8 Å at x ) 1.0, to 17.6 Å at 1 < x < 3, and to 18.3 Å at x g 3. One-dimensional electron density calculations based on X-ray diffraction data (perpendicular to layers) show that the composites contain a monolayer of PEO molecules when x < 1 and a bilayer when x g 1. The data suggest that the PEO chains are arranged side-by-side in a fully extended conformation between the layers forming corrugated mono-or bilayers. The (PEO) x V 2 O 5 ‚nH 2 O intercalation compounds are water swellable and light-sensitive. UV irradiation causes dramatic changes in the electronic structure of V 2 O 5 and results in enhanced electrical conductivity and decreased solubility. The conductivity of the irradiated products decreases as the PEO content increases. The optical absorption spectra, electrical conductivity, thermoelectric power, magnetic susceptibility, and electron paramagnetic resonance spectra of the irradiated products are self-consistent and suggest an increased V 4+ concentration in the layers and n-type charge transport. Lithium ion redox intercalation was performed on the PEO/V 2 O 5 composites by reaction with LiI. Variable-temperature 7 Li solid-state NMR studies of the Li/PEO/V 2 O 5 materials are reported.

Simulation insights on the structure of nanoscopically confined poly(ethylene oxide)

“…These simulated systems would best compare against aligned nanocomposites cast from solution, in which case the XRD patterns display several order of 00n reflections. 9,[31][32][33] As can be seen (Fig. 7), our results reproduce well the XRD patterns from experiments.…”

Cathodes for lithium ion batteries: the benefits of using nanostructured materials

“…[55][56][57][58] Among these vanadium derivatives, the layered vanadium pentoxide, LiV 2 O 5 has been the most studied in spite of its low discharge voltage, low electric conductivity and slow diffusion kinetics of lithium ion. 59,60 To improve the performance of cells employing vanadium pentoxide as cathode several tricks have been tested, including the use of aerogels, 61-63 xerogels, [64][65][66] nanocomposites of LiV 2 O 5 with electronically conducting organic polymers 17,60,[67][68][69][70][71][72][73][74][75][76][77][78] and nanostructured materials (nanotubes, nanorods and nanoparticles). [79][80][81] In general, nanotubes of V 2 O 5 are prepared by sol-gel method from the hydrolysis of vanadium (V) triisopropoxide.…”

Materiais para cátodos de baterias secundárias de lítio

“…Existem vários métodos de obtenção dessas nanoestruturas, sendo alguns deles: a polimerização de molécu-las do monômero na rede inorgânica através de um tratamento quí-mico, térmico ou fotoinduzido in situ; a intercalação do polímero previamente formado e através de uma polimerização intercalativa redox durante a preparação do óxido pelo método sol-gel, onde os monômeros são oxidados pelo material inorgânico, o qual se reduz e promove a formação do polímero entre as suas camadas 175 . PANI 176 , PPy 177 , politiofeno 178 (PTH), e poli(óxido de etileno) 179 compreendem alguns dos polímeros inseridos em matrizes hospedeiras.…”