Single and Multi-dimensional AAO Template Synthesized Heterogeneous Nanostructures for Electrochemical Energy Storage

Abstract

Anodic aluminum oxide (AAO) has been successfully used to fabricate a variety of well-ordered, regular nanostructured systems for a range of applications including electrochemical energy storage technologies. Template synthesized nanomaterials based on AAO can lead to well-designed nanoarchitectures composed of multiple favorable (high energy capacity, high electrical conductivity, strong mechanical strength) electrical energy storage materials and also one and three dimensional. Combining nanomaterials within a single system to form heterogeneous nanostructures leads to synergic effects unrealized with single components. Adding dimensionality to nanostructures potentially offers drastic improvements in both energy density and power density.

This dissertation describes the design, fabrication, and characterization of heterogeneous nanostructures based on AAO template synthesis methods for use as supercapacitor electrodes. The first approach utilizes two straightforward deposition techniques, atomic layer deposition and electrochemical deposition, for the construction of MnO<sub>2<sub>/TiN nanotube arrays. Both the inner and outer surfaces of the nanotubes, where the charge storage takes place, are exploited for enhanced capacitance. The second approach uses a novel well-ordered three-dimensional nanostructured template based on the modification of AAO during pore formation. A network of interconnecting pores is produced and demonstrates the controllable nature of AAO pore growth. An additional AAO modification to the pore barrier layer allows for electrical contact to the bottom aluminum substrate. The potential for new nanoarchitectures using the electrochemically modified AAO template, especially in multiple dimensions, is further realized using atomic layer deposition and chemical synthesis techniques.