Alumina Template Synthesis Of Tin Oxide Structure Materials

Carbonaceous materials are currently used as anode materials in commercial Lithium ion batteries. The need for smaller and lighter battery products promotes the search for new anode materials. Li-ion battery anodes derived from oxides of tin that they can store over twice as much Li as graphite. So the oxide of tin are promising materials to replace carbonaceous materials in Lithium ion battery.A nanometer-scale Al₂O₃ template with highly ordered and densely packed hexagonal pore structure is obtained by the electrochemical anodizing process in the oxalic and the sulfuric acid, the impact of the purity of the aluminium sample, the electrolyte concentration, the current density ect on the formation of the Al₂O₃ ordered film is discussed. The anodization condition is discussed and the appropriate condition in oxalic acid is concluded, and the basis of the prepare of SnO₂ nanostructure materials by Al₂O₃ template for future. The results shows that the aperture was smaller about 40nm by Al₂O₃ template in the sulfuric acid, but it is not suitable to preparing for the large aperture of SnO₂ materials. The aperture was about 100nm by Al₂O₃ template in the oxalic acid, the impact of annealing, the purity of the aluminium sample, reaction temperature, the current density ect on the formation of the Al₂O₃ ordered film is discussed. The results show that annealing is better than unannealing;the pore size and film thickness were large for the high purity;the thickness and the pore size increased as the temperature increased;the thickness increased as the oxidize time increased, when the time is up to 2h, it is not great change. The optimized process conditions areshown as follow: the purity of 99. 99%, annealing temperature 440°C , temperature 10 18°C , current density 1.25 A/dm2, the oxidize time l²h.Additionally, nanostructured SnO2 electrodes were prepared by immersing the AI203 template membrane into a tin oxide-based sol. The sol was prepared by dissolving 0. 388g of SnCI2*2H2O in a solvent mixture composed of 0. 47mL ethanol and 0. 03mL of hydrochlone acid to yield a 3M Sn(II) solution. This solution was aged for 24h to yield a very fine white precipitate. Hydrochlone acid(0.03mL) was added, and over a period of 24h the precipitate was resuspended to yield a transparent sol. The process of preparation of SnO2: Preparation of sol -*■ immerse —? drying — heat-treatment — deciduate.Finally, the charge-discharge electrochemical reaction mechanism and the cycle property was studied. The SnO2 nano-tubes have larger surface areas, and the depth of incorporation and decorporation of Li is superficial and the distance over which Li+ must diffuse in the solid state is dramatically decreased in the nanostructured electrode. Eventually, the anode materials based on SnO2 have great quality rate capacities, good cycle performance and high charge-discharge efficiency. The Li^Sn alloy/dealloy processing was studied in detail via differential specific capacities (dQ/dV), the Li^Sn alloy/dealloy appeared in 0.3V, 0.65V > 0.75V ^ 0.9V. In the galvanostatic discharge-charge experiments, the rate capacities and cycle performance of nanostructured SnO2 at low charge-discharge rates(l/4Candl/2C) is obviously better than at high rates(lC), but they all showed a large irreversible capacity lost at the first discharge. When the cycle index is up to 15 cycles, the specific capacity lose a little. The charge-discharge efficiency is about 95%.In summary, through Sol-Gel Template Processing prepared SnO2 nano-structure anode materials, having certain application prospect.