Vanadium Oxide Nanofibers and Vanadium Oxide Polyaniline Nanocomposite: Preparation, Characterization and Electrochemica
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Vanadium Oxide Nanofibers and Vanadium Oxide Polyaniline Nanocomposite: Preparation, Characterization and Electrochemical Behavior Samuel T. Lutta, Hong Dong, Peter Y. Zavalij, and M. Stanley Whittingham*
Chemistry Department and the Institute for Materials Research, State University of NewYork at Binghamton, Binghamton, NewYork 13902-6016, U.S.A. ABSTRACT The sol gel reaction of NH4VO3 and polymethylmethacrylate (PMMA) template followed by hydrothermal treatment formed (NH4)xV2O5-δ.nH2O rods. TGA, SEM, XRD and FTIR characterized this compound. Heating (NH4)xV2O5-δ.nH2O in oxygen and nitrogen at 250 oC and 300 oC respectively resulted in the formation of vanadium oxides nanofibers of V3O7 and V2O5. Performance of these compounds as cathode in rechargeable lithium battery was investigated in a LiPF6/mixed carbonate electrolyte. The materials show good cycling with capacity greater than 130mAh/g, which translates to the insertion of 0.5 moles of Li+ per vanadium of the active material. INTRODUCTION Entering the world of nanomaterials has become an exciting challenge for chemists, physicists, and materials scientists [1]. In the last decade, a vast knowledge about the synthesis and properties of various nanoparticles and nanocomposites has been collected, with new insights and discoveries emerging almost on daily basis. Moreover, materials show better performance or properties when down scaled to one dimensional nanoscropic structures [2]. Thus considering the potential use of vanadium oxides as secondary cathode materials for advanced lithium batteries [3], industrial oxidative catalysis [4] and electrochromics [5], production of nanostructured vanadium oxides is currently the focus of rapidly growing scientific community. Over the decade a number of processes have been documented for the fabrication of tubular and fibrous vanadium oxides with diameters ranging from nanometers to micrometers. Essentially two main templating approaches have been used: either coating of the metal oxide around preformed fibers, such as carbon nanotubes [6] or formation of metal oxide within preformed tubes such as those of alumina or polycarbonate membrane [7], all of which form tubes or fibers on removal of the template by calcination or chemical etching. It has also been possible to form vanadium oxide nanofibers by self-organization of the precursor in the absence of a template [8]. Recently, a new class of vanadium oxide nanotubes was obtained by a soft-chemistry synthesis involving amines with long alkyl chains as molecular, structure directing template [9]. This material consisted of scrolls of vanadium oxide layers within which the alkyl amines were embedded, and had a particularly attractive electrochemical behavior in lithium cells. In our attempt to make structured vanadium oxides, we have developed a new method to make novel vanadium oxide tubes and nanorods using organic polymer as template. In this study vanadium oxide fibers were formed *
Contact author; [email protected]
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using polymethylmethacryla
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