Reserch On Synthesis And Electrochemical Charactetriztion Of Titanium-Based Composite

In this paper, lithium titanate and lithium titanate based composites are fabricated by hydrothermal and solvothermal methods. By using different solvents, we synthesized a variety of lithium titanate and lithium titanate based composites with different morphologies. The physical and chemical characterization of the materials were studied using XRD, SEM, TEM, CV and charge-discharge test. The main contents are as follows:(1). Lithium titanate-titanium dioxide nanoparticles. Li4Ti5O12-TiO2 nanoparticles were prepared using polyethylene glycol 400 (PEG-400) as solvent, maintained 180℃ for 24 h and calcined at 550℃. The structural and morphology characterization show the products are composed of lithium titanate and titanium dioxide with the size of 100-200 nm. The electrochemical test results show that at 0.1 C ratio, Li4Ti5O12-TiO2 nanoparticles initial discharge specific capacity is up to 315 mA h g-1. At 1.0 C ratio, initial discharge specific capacity is 260 mA h g-1, and capacity retention ratio is 87% after 80 cycles. It is apparent that the Li4Ti5O12-TiO2 electrode has superior electrochemical performance.(2). Lithium titanate and lithium titanate-titanium dioxide microspheres. Li4Ti5O12 and Li4Ti5O12-TiO2 microspheres with hierarchical structures were prepared by the polyol method using glycerol as a solvent and sodium dodecyl benzene sulfonate (SDBS) as a surfactant. We could control Li4Ti5O12 and Li4Ti5O12-TiO2 by the amount of SDBS. SEM shows that Li4Ti5O12 and Li4Ti5O12-TiO2 microspheres with the size of 2-3 μm are composed of numerous nanosheets. The electrochemical test results show that at 0.5 C,1.0 C,2.0 C and 4.0 C ratio, the discharge specific capacity of Li4Ti5O12-TiO2-0.2 microspheres were 306.4, 149.8,124.7,123.1 mAhg-1.(3). Lithium titanate-titanium dioxide nanosheets. Li4Ti5O12-TiO2 nanosheets were prepared using triethylene glycol as a solvent without adding any surfactant. We tested the structure and morphologh for different pH (i. e., different source of lithium), the proportion of lithium and titanium, and different ratio of solvent.The results show that the pH has the very important role in theLi4Ti5O12-TiO2 nanosheets; with the different ratio of solvent, Li4Ti5O12-TiO2 nanosheets show various morphologh; with the different ratio of lithium and titanium, Li4Ti5O12-TiO2 nanosheets show various structure.