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The Relationship Between Nanoscale Structure and Electrochemical Properties of Vanadium Oxide Nanorolls
Author(s) -
Sun D.,
Kwon C. W.,
Baure G.,
Richman E.,
MacLean J.,
Dunn B.,
Tolbert S. H.
Publication year - 2004
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200400056
Subject(s) - materials science , vanadium , vanadium oxide , x ray photoelectron spectroscopy , oxide , orthorhombic crystal system , nanoscopic scale , electrochemistry , oxidation state , transmission electron microscopy , cyclic voltammetry , inorganic chemistry , chemical engineering , crystallography , nanotechnology , metal , crystal structure , electrode , chemistry , metallurgy , engineering
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 V 2 O 5 . 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.