Nanostructured materials for high performance energy storage and conversion devices

Abstract

With the growth of population and changing of the lifestyles, our global energy demands is increasing dramatically. Since the traditional fossil fuel resource is very limited, it is necessary and urgent to pursuit sustainable energy alternatives, including both green energy sources and sustainable energy storage systems.

Solar energy is the most promising alternative of clean energy source, since it is clean, abundance and widely available at most places on the earth. Recently, the dye-sensitized solar cell (DSSC) has attracted increasing research interests for its low cost and long lifetime. Moreover, to make the best use of the energy sources, it is needed to develop suitable energy storage system. Lithium ion battery (LIB) has becoming the key technology for energy storage, especially in recent years. It has been widely used in portable devices like smart phones, PCs and wearable electronic devices. More importantly, due to the high energy density of lithium ion battery, it has become the most promising and critical energy storage technologies for electric vehicles (EV) and hybrid electric vehicles (HEV). In both DSSCs and LIBs, metal oxides represent important parts of the devices.

This dissertation covers the basic principle as well as the strategies for performance enhancing of both lithium ion batteries and dye-sensitized solar cells. Various TiO2 based anode materials for LIBs were investigated. The morphology and structure would significant affect the lithium storage of TiO2 anode; a simple in situ fabrication procedure was developed to further enhance the capacity of TiO2 nanotube anode. Moreover, in order to develop high energy density materials, SnO2 based anode materials were investigated. Composite materials of tin and copper oxides on CNT matrix as well as Al2O3 stabilized SnO2 hollow sphere with GO wrapped anodes were fabricated and studied. The composite anode is an efficient way to increase the stability of the electrode upon cycling. For the energy conversion, ZnO-based DSSCs were studied. We developed a low temperature (150C) procedures for ZnO-based DSSCs, the low temperature procedure is less energy consuming, and may have the potential usage on future flexible devices.