Preparation of V2O5 aerogels and aerogel coatings

Hirashima, Hiroshi; Sudoh, Kazumi

doi:10.1016/s0022-3093(05)80428-4

Cited by 25 publications

(12 citation statements)

References 4 publications

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“…Vanadium oxide aerogels have been prepared by supercritical drying at high temperature (from ethanol) 102,103 and low temperature (from CO 2 ). [104][105][106] Ambient-pressure methods have also been reported.…”

Section: Vanadium Oxide Aerogelsmentioning

confidence: 99%

Electrically conductive oxide aerogels: new materials in electrochemistry

Rolison

Dunn²

2001

J. Mater. Chem.

355

295

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Section: Vanadium Oxide Aerogelsmentioning

confidence: 99%

Electrically conductive oxide aerogels: new materials in electrochemistry

Rolison

Dunn²

2001

J. Mater. Chem.

355

295

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“…For some applications, microporous solgel thin films may be appropriate. V 2 O 5 thin films have been prepared from gels using either spin-coating [3][4][5][6] or dip-coating [7][8][9] methods. The aim of this work is to present a structural, optical and electrochromic study of V 2 O 5 thin films prepared by sol-gel spin coating route.…”

Section: Introductionmentioning

confidence: 99%

Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Benmoussa

Outzourhit

Jourdani

et al. 2003

Active and Passive Electronic Components

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Vanadium pentoxide thin films are prepared by the sol-gel route by dissolving V 2 O 5 powder (99.5% purity) in H 2 O 2 solution. The solution is spin-coated on glass substrates for optical (UV-VIS-NIR) and XRD analysis, and on ITOcoated glass substrates for electrochromic measurements. The samples are then annealed at 150 C for 1 hour. The resulting films have a yellow-orange color, typical of polycrystalline V 2 O 5 . XRD measurements have shown that after annealing in air at 400 C the structure of the films has a c-axis preferred orientation, the (0 0 1)-type planes lying parallel to the substrate. SEM analysis revealed a smooth surface. The films' optical and physical constants (n, a, Eg, the thickness d and the mean thickness inhomogeneity s) are calculated using a simple and accurate method based on the transmission spectrum alone. The films' electrochromism is studied using cyclic voltammetry (CV) and chronoamperometry in propylene carbonate solution containing 1 mol=l LiClO 4 . The films show reversible multichromism (yellow-green-blue) upon Li þ ion insertion=extraction. The absorbance of films colored at three different potentials is measured in the UV-VIS-PIR wavelength range, and this study shows that the changes in the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

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“…[1][2][3][4][5][6] Due to the difficulty in controlling the reaction rate in this process, however, a complexing agent such as acetyl acetone or acetic acid is commonly added. Another sol-gel method for vanadium oxides is the acidification of sodium metavanadate solution using ionexchange resin.…”

mentioning

confidence: 99%

Li[sup +] Storage Sites in Amorphous V[sub 2]O[sub 5] Prepared by Precipitation Method

Kim

et al. 2003

J. Electrochem. Soc.

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Amorphous vanadium oxide (a-V 2 O 5 ) powders were prepared by acidifying aqueous NH 4 VO 3 solution with concentrated nitric acid. Samples having a different degree of layer stacking and surface area were obtained either by changing the NH 4 VO 3 concentration or by employing additional solvent exchange process. The pentane-exchanged precipitate gave the largest surface area (60 m 2 g -1 ) after vacuum drying at 100°C for 24 h. This electrode material delivered an initial discharge capacity of 426 mAh g Ϫ1 in the voltage range of 1.5-4.0 V ͑vs. Li/Li ϩ ), which amounts to 2.9 equiv Li ϩ ions per mol of V 2 O 5 . X-ray absorption near-edge spectra ͑XANES͒ clearly showed a vanadium reduction down to V͑III͒ when Li ϩ ions were inserted at Li ϩ /V 2 O 5 Ͼ 2.0. The Li ϩ storage sites were analyzed by correlating the peak intensity in differential capacity plots to the surface area and degree of layer stacking, from which two different Li ϩ storage sites were identified. The discharging capacity at 1.7 V was strongly correlated with the surface area of electrode material, suggesting that Li ϩ ions are inserted into the amorphous region at this potential. The intensity of 2.5 V peak was, however, proportional to the peak intensity of ͑001͒ diffraction, illustrating that Li ϩ ions are inserted into the quasi-ordered layer stacking region at this potential. The latter feature was further confirmed by X-ray diffraction analysis, whereby it was found that the interlayer spacing decreases most significantly near 2.5 V along with a sharp decrease in the ͑001͒ diffraction intensity.Recently, sol-gel process has become widely used for preparing amorphous vanadium oxides via hydrolysis and condensation reaction of molecular precursors such as vanadium alkoxides. 1-6 Due to the difficulty in controlling the reaction rate in this process, however, a complexing agent such as acetyl acetone or acetic acid is commonly added. Another sol-gel method for vanadium oxides is the acidification of sodium metavanadate solution using ionexchange resin. 7-12 A problem in this process is the contamination of Na ϩ ions in the products and the difficulty in large-scale production. In these sol-gel processes, vanadium oxide xerogels are obtained upon drying the resulting gels under ambient condition or after solvent exchange. [13][14][15] The gels can also be converted to aerogels by supercritical drying. 16,17 Amorphous vanadium oxide xerogels or aerogels are known to have a higher Li ϩ storage ability than the crystalline analogue when they are tested as the cathode material in Li secondary batteries. Four equivalents of lithium insertion per mole of V 2 O 5 aerogel is frequently observed by chemical or electrochemical lithiation. 10 Moreover, some reports claimed even higher Li ϩ storage capacity up to 5.8 equiv per mol of V 2 O 5 . 18 This high capacity has been ascribed in the literature to the amorphous structure and high surface area of these materials. 19,20 In this work, we utilized the rapid precipitation method to obtain amorphous vana...

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Preparation of V2O5 aerogels and aerogel coatings

Cited by 25 publications

References 4 publications

Electrically conductive oxide aerogels: new materials in electrochemistry

Electrically conductive oxide aerogels: new materials in electrochemistry

Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Li[sup +] Storage Sites in Amorphous V[sub 2]O[sub 5] Prepared by Precipitation Method

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Preparation of V2O5 aerogels and aerogel coatings

Cited by 25 publications

References 4 publications

Electrically conductive oxide aerogels: new materials in electrochemistry

Electrically conductive oxide aerogels: new materials in electrochemistry

Structural, Optical and Electrochromic Properties of Sol–Gel V2O5Thin Films

Li[sup +] Storage Sites in Amorphous V[sub 2]O[sub 5] Prepared by Precipitation Method

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Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films