Preparation And Electrochemical Properties Of TiO₂ And TiO₂/GO Anode Materials For Lithium Ion Batteries

Currently, lithium ion batteries have been widely used in portable electronic devices,and graphite is the most commonly used in anode materials. However, there are serious safety problems during charge-discharge cycling. In recent years, with the development of hybrid and plug-inhybrid, the electrochemical performance of Li-ion batteries need to be further improved. Therefore, we are looking for new materials that can replace the traditional graphite as anode materials in Li-ion batteries. Titanium dioxide is a low cost environmentally benign material. TiO2 is also structually stable during Li-insertion or extraction and is intrinsically safe by avoiding Li electrochemical deposition. These properties make TiO2 particularly attractive for high power energy storage. But TiO2 suffers slow Li-ion diffusion, poor electron transport in the aspect of the electrode. This article discussed from the perspective of the microstructure and adding conductive agents.We have prepared various TiO2 with different morphology, such as hollow decahedral anatase TiO2, hierarchical rutile TiO2 microspheres assembled by nanorods,three-dimensional grid structure of TiO2/GO compound and two-dimensional nanoflake TiO2/GO nanocomposites. The electrochemical performance related to these materials are studied. The main conclusions have been summarized as following:1. Hollow decahedral anatase TiO2 with exposed(001) facets is synthesized by a hydrothermal method when hydrofluoric acid volume is 0.09 mL. The hollow decahedral anatase TiO2 with exposed(001) facets exhibits excellent electrochemical performance:the specific capacity is 196.4mAhg-1 in the first discharge cycle at 0.1C and the initial irreversible loss is just 13.29%, indicating excellent stability.2.In order to improve the lithium ion diffusion, the hierarchical microspheres assembled by rodlike rutile TiO2 can be prepared via a one-pot method under low temperature. The diameter of the microsphere is 30-40μm. The microspheres are actually constructed from nanorods with diameter of 40-50 nm. This experiment provides a new facile, short time and simple operation method for synthesizing hierarchical rutile TiO2 microspheres at low temperature. The first discharge specific capacity of the rutile TiO2 is up to 187.6mAh?g-1 at 0.1C.3. In order to enhance the charge transfer process of anatase TiO2, the TiO2/GO nanocomposites with different structure have been prepared by a simple one-step solvothermal method. Three-dimensional grid structure of TiO2/GO nanocomposite(3DTG)is synthesized. Comparied with P25, the 3DTG exhibits excellent capability, the initial specific capacity is 192.6mAh?g-1 at 0.1C, which is higher than the specific capacity of P25(134.00mAh?g-1) under the same experimental conditions. Two-dimensional structure of TiO2/GO nanocomposite(TG) is prepared, TiO2 nanoparticles have a wide size distribution of 20-30 nm. The TG exhibits outstanding electrochemical performance in the first discharge cycle at 0.1C, the specific capacity is 280.5mAhg-1.