Three-dimensional Nanostructured Electrodes:Synthesis And Application As Anode For Lithium-ion Batteries

Lithium-ion batteries have been widely used in portable electronic devices and greatly affect the industry, science and technology due to many advantages such as enviromentally friendly, high power density and long cycle life. Recently, higher power density, longer cycle life, and wider range of working temperature are demanded in lithium-ion batteries because of the fast development of the power type applications.The three-dimensional (3D) nanostructured electrodes have received great interest for Lithium-ion batteries, which show significant advantages in their kinetics and electronic conduction during the charge-discharge process. Therefore,3D nanostructured electrodes are expected to show higher capacities, good cycling stability and rate capability, and thus have been considered as one of the promising choices for next generation lithium-ion batteries.In this dissertation, we prepare several kinds of3D nanostructured electrodes for lithium-ion batteries via different ways:we propose a nanoarray template assisted method to obtain SnO2nanotube arrays; we propose a facil template-engaged approach for Cu nanoporous3D current collect, which can support Si, Ge, SiGe and Sn to form porous3D nanostructured electrode; besides, we propose a template-assisted method for Cu nanwire arrays as current collector, which can support Ge, Sn, Si1-xGex and Mn3O4to form3D electrode. Owing to the unique structure, the above-mentioned3D nanostructured electrodes exhibit improved electrochemical performance. The main innovative results are listed as follows:(1) By using a pre-fabricated ZnO nanowire arrays as sacrificial templates, SnO2layer has been coated onto the surface of ZnO nanowires by a hydrothermal process. After HC1solution etching, SnO2nanotube arrays on titanium substrate are obtained. The as-synthesized SnO2nanotube arrays are applied as anode materials for Li-ion battery, which exhibit high capacity and good cycling performance.(2) By employing a Cu nanwire arrays as current collector, Cu-Ge, Cu-Sn, Cu-Si1-xGex and Cu-Mn3O4core-shell nanowire arrays3D electrode have been obtained. The four kinds of3D nanostructured electrodes all exhibit good cycling stability and rate capability. (3) We propose that alloying Ge with Si could improve the electrochemical performance of Si. The effect of Ge content on the electrochemical performance of Si-based materials has also been investigated.(4) We demonstrate the synthesis of Cu nanoporous three-dimensional network via a simple template-assisted method. The network could be used as a universal current collector for lithium-ion batteries.(5) By using this3D network as current collector, Si, Ge, SiGe and Sn porous3D nanostructured electrode have been prepared. The as-prepared four kinds of porous3D nanostructured electrodes exhibit improved cycling stability and rate capability compared to corresponding planar electrodes.