Synthesis and electrochemical properties of carbon nanotubes and silicon nanowires

This dissertation describes the room-temperature electrochemical reactions between lithium and two novel one-dimensional (1D) nano-materials, carbon nanotubes (CNTs) and silicon nanowires (SiNWs). These materials have quite different electrochemical properties from their bulk phase counterparts, graphite and bulk phase silicon.; Carbon nanotubes provide interesting one-dimensional host materials for intercalation reactions. In this study, both multi-walled (MWNTs) and single-walled carbon nanotubes (SWNTs) are intercalated successfully with lithium by electrochemical methods. The electrochemical properties of carbon nanotubes (CNTs) have been found to be closely related to their real (defective) structures. Different processing methods modify the structures of carbon nanotubes (CNTs) and change their electrochemical properties dramatically. It has been shown that properly processed SWNTs can have a reversible lithium capacity as high as ∼1000mAh/g (Li_2.69C₆), more than twice the theoretical value of graphite (372mAh/g or LiC₆).; Electrochemical reaction between silicon nanowires (SiNWs) and lithium has been found to proceed readily at room temperature. This is in sharp contrast with that of bulk phase silicon where such reaction only happens at high temperature (∼400°C). The results indicate that chemical reactivity of these nanostructured materials varies with the size of their critical building blocks. The high reversible capacity, low voltage hysteresis and low charge/discharge voltage respected to Li/Li+ make SiNWs a promising candidate for anode materials in lithium-ion batteries.; This work also demonstrates that electrophoretic deposition (EPD) is an efficient technique to make SWNTs films. The SWNT films fabricated by electrophoretic deposition (EPD) exhibit very good uniformity and adhesion with the substrate. The SWNT films fabricated by electrophoretic deposition (EPD) show excellent electron emission stability, especially at high macroscopic emission current (1.7mA or 30mA/cm2).