V2O5 xerogel electrodes with much enhanced lithium-ion intercalation properties with N2 annealing (original) (raw)
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Dip-coated silver-doped V2O5 xerogels as host materials for lithium intercalation
Solid State Ionics, 1997
Vanadium pentoxide xerogels have shown high electrochemical performance in terms of energy content. The high specific energy and high intercalation capability make the materials promising for thin tilm lithium battery and clcctrochromic device applications. In order to enhance the rate capabilities of the host we increased the electronic conductivity by doping the VTOs xcrogels with silver. Samples were prepared by mixing various amounts of silver powder with V,O, hydrogel. We were able to prepare silver-doped vanadium pentoxide dip-coated thin films with a molar ratio (Ag/V) ranging from 0.005 to 0.5 (Ag rVzO, with y = 0.0 I, 0. I and I). With the successful doping, the electronic conductivity of VzO, was increased by 2 to 3 orders of magnitude. The insertion capacity of the material was maintained and up to 4 moles of lithium per mole of silver-doped V,O, (XRG) were found to be reversibly intercalated.
Electrochemical behaviour of V2O5 xerogel in aqueous LiNO3 solution
Electrochemistry Communications, 2009
By dissolving crystalline V 2 O 5 in hydrogen peroxide and drying at elevated temperature, the V 2 O 5 xerogel was obtained. Its electrochemical behaviour was examined in aqueous solution of LiNO 3 by both cyclic voltammetry and galvanostatic charging/discharging cycling. Peak-to-peak potential separation observed at the cyclovoltammograms indicated fast Li + intercalation/deintercalation reactions. Initial discharge capacity amounted to 69 mAhg À1 , and after 100 charging/discharging cycles, capacity fade amounted to 11% only. This presents a remarkable improvement in comparison with the behaviour of crystalline, vanadium oxide based, lithium intercalates in aqueous electrolytes.
Journal of The Electrochemical Society, 1999
Vanadium pentoxide materials prepared through sol-gel processes act as excellent intercalation hosts for lithium as well as for polyvalent cations. Previous ex situ X-ray absorption spectroscopy and X-ray diffraction characterizations have shown that the electrochemical performance of vanadium pentoxide xerogels depends inversely on the long-range order of the V 2 O 5 -layered structure. Recently, new ways to prevent the self-organization of the dry materials, which takes place upon water removal from the starting hydrogel, have been introduced. In the present paper we report on the in situ X-ray absorption spectroscopy characterization of a spray-coated V 2 O 5 (freeze-dried) xerogel cathode upon lithium intercalation.
V2O5 Aerogel as a Versatile Cathode Material for Lithium and Sodium Batteries
ChemElectroChem, 2015
Vanadium oxide gels are appealing cathode materials as they offer multiple electron redox processes leading to high cation‐storage capacities. Moreover, they are able to intercalate different ionic and molecular species. Apart from low electronic conductivity, one of the main factors hindering the use of highly porous V2O5 gels is the difficulty in preserving their unique morphology, made up of an entangled network of thin ribbons, during conventional laminated electrode preparation. In this study, we tune the V2O5 synthesis conditions and use an innovative and green binder system (polyacrylic acid and ethanol) to obtain electrodes with a morphology optimized for ion intercalation. The electrochemical performance of such electrodes, tested against lithium and sodium anodes, are shown to be excellent.
XAS and electrochemical characterization of lithiated high surface area V2O5 aerogels
Solid State Ionics, 1997
V O aerogel (ARG) has been recently proposed as cathode material for rechargeable lithium batteries. Such a material is 2 5 2 amorphous and consists of a highly interconnected solid network with a surface area up to 450 m / g, and a specific pore 3 volume as much as 2.3 cm / g. In a previous paper, it was shown that up to 4 equivalents of lithium per mole of V O 2 5 aerogel can be inserted by means of chemical or electrochemical lithiation. In the present work, the lithium composition range has been extended. By chemical lithiation (CL) a composition Li V O , the highest ever reported for any vanadium 5.8 2 5 oxide host, was achieved. The equilibrium open circuit voltage (OCV)-composition curve of the chemically lithiated aerogel samples showed a wide plateau extending up to 5.8 equivalents of lithium per mole of V O. The surprisingly high OCV has 2 5 been correlated with the characteristic morphology and structure of the aerogel material by means of X-ray diffraction and absorption and XPS spectroscopies.
Electrochemical conditioning of vanadium(V) pentoxide xerogel films
Electrochemistry Communications, 1999
The electrochemical behavior of layered vanadium(V) pentoxide xerogel films has been studied, focusing on the lithium intercalation and reorganization effects accompanying the electrode conditioning process. The films at the initial condition consist of electrochemically heterogeneous regions, which collapse into a uniform band structure as the lithium ions are inserted into the interlamellar space. At the saturation point, a single broad intervalence-transfer band is observed in the visible-near infrared region, and the electrochemical behavior becomes independent of the diffusion process.
2010
We synthesized both the V 2 O 5 xerogel and the composite V 2 O 5 xerogel/C starting from the solution of V 2 O 5 in hydrogen peroxide. After the characterization by XRD, thermal (TGA-DTA), SEM methods and by particle size analysis, the investigation of Li + and Mg 2+ intercalation/deintercalation reactions in an aqueous solutions of LiNO 3 and Mg(NO 3) 2 were performed by cyclic voltammetry. The composite material V 2 O 5 xerogel/C displayed relatively high intercalation capacity, amounting to 123 mA h g −1 and 107 mA h g −1 , in lithium and magnesium salt solutions, respectively.
Spin-Coated V2O5 Xerogel Thin Films. 1. Microstructure and Morphology
Chemistry of Materials, 1995
Vanadium pentoxide xerogel films spin-coated on nickeYsilicon substrates have shown high electrochemical performance. In fact, more than 3 equiv of lithium Vz05 unit can be reversibly inserted between 3.5 and 1.6 V in aprotic electrolytes. The high insertion capacity coupled with the inexpensive and well-known preparation procedure make the material interesting for thin-film lithium battery and electrochromic device applications. In the present paper we report the characterization of such thin films based on X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz crystal microbalance, optical, and electronic conductivity measurements. The spin-coated films are highly amorphous, with a small amount of ribbon stacking that is randomly oriented. The disorder is caused by the joint effect of high shear and rapid drying during spin coating.