Fundamental Study of the Synthesis, Structural and Electrochemical Characterization of Nanoparticulate Transition Metal Oxide and Nitride Based Supercapacitor SystemsJampani Hanumantha, Prashanth (2015) Fundamental Study of the Synthesis, Structural and Electrochemical Characterization of Nanoparticulate Transition Metal Oxide and Nitride Based Supercapacitor Systems. Doctoral Dissertation, University of Pittsburgh. (Unpublished) This is the latest version of this item.
AbstractSupercapacitors are electrochemical charge storage devices capable of delivering large bursts of charge over a very short period of time. There is a need for identification and development of alternative low-cost, high energy, high-power materials for widespread implementation of supercapacitor technologies. Nanostructured vanadium nitride (VN) coated with a thin vanadium oxide (VOx) surface layer has previously been identified to be a very promising electrode material for supercapacitor application. The investigations conducted in the nitride systems made it clear that the prodigious amount of charge storage in nitride nanomaterials was primarily due to a surface oxide layer and that the stabilization and improvement in electronic conductivity of the surface oxide was pivotal in attaining a reversible and stable charge storage. Nanostructured oxides of vanadium (VOx) as standalone supercapacitor materials were therefore explored. Thin films of vanadium oxide were deposited on an array of vertically aligned carbon nanotubes (VACNTs) derived using chemical vapor deposition (CVD). This study also made it very clear that the presence of a conductive support structure is imperative to achieve good charge storage response in oxides. Using dopants identified by ab-initio computational studies of doped vanadium oxide materials (VOx: M), very high areal and gravimetric capacitances in doped materials coated on VACNTs was demonstrated. Identical doping strategies were used to derive doped vanadium nitride (MyV1-yN) with a doped surface oxide layer (MyV1-yOx). Dopants were selected on the basis of improvement in electronic conductivity without compromising the chemical stability. Improvement in charge storage properties of nanoparticulate nitride particles by systematic tailoring of the architecture was demonstrated. Share
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