The Reaction Mechanism Analysis For The Lithium Titanate Synthesized By The Solid State Reaction

The spinel type lithium titanate(Li4Ti5O12) with its security,long lifetime,and high electricity has a good value in both study and business application. The solid state reaction which mixed the nanoscopic rutil or anatase titanium dioxide with the lithium carbonate of stability,security, and cheapness by mechanic ball milling could synthesized the micro-sized or nanoscopic lithium titanate and highly improved the electrochemical performances. In this article by changing the epichlorohydrin, the interphase Li2TiO3 was sintered by the one-step solid station. Once again the pure lithium titanate particles about 270nm was synthesized. As the reaction characteristic,whether the reaction occurrence, the conversion degree, and the reaction controlling step will directly influence structure and property of the final production, it has a significant importance to analysis the reaction mechanism of the processs.Adopting the isothermal/variable temperature experiments, measurement as High Temperature Ⅹ-ray Diffraction (HTXRD)was used to analysis the phase changed while the reaction procedure, The thermal decomposition behavior of the precursors was characterized by Thermogravimetry analysis (TG) and differential thermal analysis (DTA) using a Simultaneous Thermal Analyzer to study the reaction mechanism. The particle morphology and average particle size of the products were observed by scanning electron microscopy (SEM). Ⅹ-ray Diffraction sumiquantatitive analysis was used to analysis the phase compositons, and the production crystallinity was dicussed. On the basis above,the mechanism of the solid state reaction was studied.The Li2TiO3 was synthesized by one-step solid state reaction with Li2CO3 and TiO2 as raw materials. In order to analysis the reaction dynamic process, five TG-DTA curves at different heating rate of 5/10/15/20/25K/min were obtained to study the ranged temperature reaction kinetics of the monoclinic Li2TiO3 production. According to the results, the reaction kinetics mechanism could be properly described as the Jander equation of a three dimensional diffusion with spherical symmetry. Through the FWO and FRL methods the approach E and A means were calculated. And, the thermo gravimetric experiments at different constant temperatures, similar regulars curves of the reaction kinetics were detected, the process at the constant temperature of 600℃ for 120 minutes had the completest reaction degree, and the process was mainly controlled by the diffusion reaction. To analysis the reaction of Li4Ti5O12 synthesized by Li2TiO3 with the isothermal experiment, K numbers was used to sumiquantatitive the production compositions,.Equations as three dimensional diffusion of Jander and Ginstling and Brounshtein can described the reaction procedure properly. The constant temperature had a deeply effect on the reaction process, the reaction velocity seemed more quickly when the temperature was higher.According to the statistical results of the partical size, the lithium titanate grain growth follows certain patterns, and the activation energy E was calculated between 135～145kJ·mol-1,the dynamic exponent of the grain grow process was n=5.74612.Combination with the different dynamic exponent, surmised that the grain grow process in accordance with the Brook grain growth models of sextic equation.