Synthesis And Characterization Of Li₄Ti₅O₁₂and Li₂Ti₃O₇as Anode Materials For Li-ion Batteries

Lithium titanate (Li4Ti5O12and LiTi3O7) were synthesized by solid-state reaction (SSR), microwave solid-state reaction (MSSR), hydro-thermal method (HTM) and microwave hydro-thermal method (MHTM), respectively. These materials were characterized by Thermogravimetry-differential thermoanalysis (TG-DTA), X-ray Diffraction (XRD), Scan electron microscope (SEM), Particle size analysis (PSA) and investigated by constant current charge-discharge test, AC impedance, Cycle Voltammagram (CV), and then were used as lithium-ion battery anode materials. Studies on the electrochemical properties and the different preparing process of lithium-ion battery anode materials, Li4Ti5O12and Li2Ti3O7, were carried out in this paper.The infection of the synthesis conditions of Li4Ti5O12and LiTi3O7prepared by SSR were first investigated. The results demonstrated that the characteristic of raw materials, sinter temperature, proportion of Li/Ti had important influence on the electrochemical properties of the materials. The Li4Ti5O12materials got the capacity of134.2mAh·g-1were prepared with Li2CO3and amorphous TiO2as the starting materials with n(Li)/n(Ti)=0.84after being sintered at800℃for6h. The Li2Ti3O7materials got the capacity of109.6mAh·g-1were prepared with Li2CO3and amorphous TiO2as the starting materials with n(Li)/n(Ti)=0.70after being sintered at1100℃for6h.Li4Ti5O12and Li2Ti3O7were then synthesized by HTM, different operation such as raw materials, reaction temperature, reaction time were investigated to get the ideal experimental flow. The results showed that the Li4Ti5O12materials prepared with Li2CO3and amorphous TiO2as the starting materials with n(Li)/n(Ti)=0.80in hydrothermal at160℃for24h and then sintered at800℃for6h had the capacity of154.2mAh·g-1and better cycling performance. The Li2Ti3O7materials prepared with Li2CO3and amorphous TiO2as the starting materials with n(Li)/n(Ti)=0.67in hydrothermal at160℃for24h and then sintered at1100℃for6h had the capacity of124.4mAh·g-1and better cycling performance.In this study Li4Ti5O12and Li2Ti3O7were also innovatively synthesized by MSSR and MHTM, respectively. Although there were some impurities in the product, and the capacity and cycling performance of the materials were not so good as materials synthesized by SSR and HTM, they will continue to be studied because of its less time consuming and low energy consumption.It is discovered that the Li2Ti3O7materials prepared by different process had lower capacity and proportion of the discharge platform compared with the Li4Ti5O12materials, but cycle performance was much better.