TEMPLATE SYNTHESIZED NANOTUBES, NANOWIRES AND HETEROGENEOUS COAXIAL NANOWIRES FOR ELECTROCHEMICAL ENERGY STORAGE
Lee, Sang Bok
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Template synthesized nanomaterials have been successfully applied in electrochemical energy storage systems such as supercapacitors and lithium ion batteries. The first part of present study will list examples of applying various nanomaterials such as nanowires, nanotubes and heterostructured nanowires in different electrochemical energy storage systems for enhancing their charge/discharge rates, energy densities and power densities, etc. The following of the thesis will describe the template synthesis of nanomaterials in details. The experimental part of this thesis will concentrate on the fabrication of alumina template and the detailed experimental setups for aluminum anodization and template synthesis of nanomaterials. The rest of the thesis analyzes four cases of using template synthesized nanomaterials in electrochemical energy storage, which include my major work during my PhD studies. The first one is utilizing poly(3,4- ethylenedioxythiophene) (PEDOT) nanotubes as electrode materials for highpowered supercapacitor. The thin-walled nanotubes allow fast charge/discharge of the PEDOT to achieve high power. The second one is related to synthesis and characterization of RuO2/PEDOT composite nanotubes for supercapacitors. Loading appropriate amount of RuO2 can effectively enhance the specific capacitance of PEDOT nanotube. The third case illustrates the synthesis of MnO2/PEDOT coaxial nanowires by one step coelectrodeposition for electrochemical energy storage. The combined properties of MnO2 and PEDOT enable the coaxial nanowires to have very high specific capacitances at high current densities. Their formation mechanism will be explored and their nanostructures are tuned for optimized electrochemical properties. The final case reports the MnO2-Nanoparticles enriched PEDOT nanowires for enhanced electrochemical energy storage capacity. Large amount of the MnO2 nanoparticles can be loaded into PEDOT nanowires after they are soaked in KMnO4 solution. Thus loaded MnO2 nanoparticles effective enhance the energy densities of PEDOT nanowires without causing too much volume expansion to them.