The Relationship Between Nanoscale Structure and Electrochemical Properties of Vanadium Oxide Nanorolls

Abstract

In this paper, we explore the relationship between the nanoscale structure and electrochemical performance of nanoscale scrolls of vanadium oxides (vanadium oxide nanorolls). The vanadium oxide nanorolls, which are synthesized through a ligand‐assisted templating method, exhibit different morphologies and properties depending upon the synthetic conditions. Under highly reducing conditions, nearly perfect scrolls can be produced which have essentially no cracks in the walls (well‐ordered nanorolls). If the materials are produced under less reducing conditions, nanorolls with many cracks in the oxide walls can be generated (defect‐rich nanorolls). Both types of samples were examined by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and X‐ray photoemission spectroscopy (XPS) to characterize their local structure, local redox state, and nanoscale structure. After ion‐exchange to replace the templating ammonium ions with Na+, the ability of these materials to electrochemically intercalate lithium reversibly was investigated. In sweep voltammetry experiments, the well‐ordered nanorolls showed responses similar to those seen in crystalline orthorhombic V2O5. In contrast, the defect‐rich vanadium oxide nanorolls behaved electrochemically more like sol–gel‐prepared vanadium oxide materials. Moreover, the specific capacity of the well‐ordered nanorolls was about 240 mA h g–1 while that of the defect rich nanorolls was found to be as much as 340 mA h g–1 under these same conditions. Disorders on both the atomic and nanometer length scales are believed to contribute to this difference.

Reduced Surfactant Uptake in Three Dimensional Assemblies of VOx Nanotubes Improves Reversible Li+ Intercalation and Charge Capacity

“…Thus, there are more amine molecules incorporated in better ordered xerogel-based nanotubes, facilitated by electrostatic binding caused by their reduction to alkylammonium ions in the presence of sufficient water. Furthermore, in contrast to previous reports [36] , we did not employ any reducing agent during synthesis to distinctly vary or control the vanadium valency ratio…”

“…Two independent groups have recently reviewed [34,35] the potential advantages and associated potential 3-D structures for use as high intercalation volume for charge storage. The role of defect-rich vanadate nanostructures in improving the specific charge capacity upon Li + intercalation compared to those without defects [36] was outlined. properties.…”

Vanadate Conformation Variations in Vanadium Pentoxide Nanostructures

“…Attempts have previously been made to determine this ratio in VOx nanorolls [33] using X-ray photoelectron spectroscopy (XPS) but no efforts have yet been reported for vibrational spectroscopic determination nor for structures other than those composed of rolled VOx lamina.…”

“…These differences are due to the different interlaminar distance caused by organic chains of different lengths and/or conformation between vanadate layers [15], discussed in more detail in Section III.C. An ordered arrangement of surfactant molecules between vanadate layers ensures rigidity against bending deformations [33]. Figure 9 shows the infrared vibrational spectra of the nano-urchin, nanotubes and nanorods of vanadium pentoxide, synthesized with the HDA surfactant, but in the lower wavenumber region where nanocomposite conformation-specific information is observed, specifically between 1020 and 900 cm −1 .…”

High-Performance Li-ion Batteries and Supercapacitors Based on Prospective 1-D Nanomaterials

“…Sun et al synthesized vanadium oxide nanorolls through a ligand-assisted templating method. The well-ordered nanorolls show responses similar to those seen in crystalline orthorhombic V 2 O 5 , while the defect-rich vanadium oxide nanorolls behave electrochemically more like sol-gel-prepared vanadium oxide materials [12]. Takahashi and co-workers prepared Ni/V 2 O 5 · nH 2 O core-shell nanocable arrays via formation of Ni nanorod arrays through the template based electrochemical deposition, followed by coating of V 2 O 5 · nH 2 O on Ni nanorods through electrophoretic deposition.…”