Study On Synthesis Of Li₄Ti₅O₁₂ By High-energy Ball Milling Method

Anode material of lithium-ion battery, spinel Li₄Ti₅O₁₂was seen as “zerostrain” insertioncompound due to its almost unchanged structure after charge-discharge process. Compared toother anode, it possessed so many advantages, such as a wide rang of raw materials, low cost,simple preparation, high stability, high potential, high life, high Li+diffusion and coefficientand so on. And it has been becoming more and more popular as an widely used motive forcelithium-ion battery for cathode material. But its tap density is only about0.8g·cm-3, which ledto a bitterly lower volume capacity and so a restriction to its industry application. This papercame up with a plan that shown how to synthesis pure phase spinel Li₄Ti₅O₁₂with excellentperformances by simple means.This paper adopted high-energy ball milling method to mechanically activate TiO₂andLi₂CO₃raw materials at room temperature, and then completed the reaction following by ahigh temperature calcination. The high-energy ball milling powders were blended by submicrometer-sized particles. The high-energy ball milling precursor, phase transformation, andfinal samples were analyzed using X-ray diffraction （XRD）, environmental scanning electronmicroscope （ESEM）, transmission electron microscope （TEM）, thermo gravimetric anddifferential scanning calorimeter （TG-DSC）, laser particle size and tap density, et al methods.It was found in the research that the high-energy ball milling technology remarkablyaccelerated the high temperature solid-state reaction, and this enhanced effect was increasedwith the activation time （ball milling time）, but it did not change the mechanism of thereaction. The TG-DSC test result of different ball milling times displayed that the promotioneffects of the formation of the reaction products was shown in the decrease of the formationtemperature, as well as in the increased reaction rate. The result of laser particle size testshown that contributed to the high-energy ball milling the particles mixed insubmicrometer-size stated at about200nm, with small amount of impurity under0.02%. Thefinal sample Li₄Ti₅O₁₂was synthesis by controlling the ratio of Li₂CO₃and TiO₂as rawmaterials, calcined temperature and holding time. Above all, the best synthesis temperatureand holding time are respectively800℃and3h, and its lattice parameter was0.83583nmwhich is so close to the standard value.In order to raise tap density of spinel lithium titanium, this paper use Zn（CH3COO）2、Li₂CO₃and TiO₂as raw materials, to synthesis Zn²⁺doping final sample Li4-xZn3xTi5-xO12.Use XRD method to analyze the crystal structure of final samples, the experiment resultshown that Zn²⁺doped samples remained the crystal structure of pure phase Li₄Ti₅O₁₂asspinel type. But with the increasing of the amount of Zn, calcination temperature and time, the tap density raised. The tap density of Li_3.933Zn_0.1Ti_4.967O₁reached1.23g·cm-3, at850℃and3h calcination.