The Modification And Electrochemical Properties Study Of Li₄Ti₅O₁₂ Anode Materials Of Lithium-ion Battery

Spinel lithium titanate (Li₄Ti₅O₁₂) has been demonstrated as a potential candidate for theanode electrode material in high power lithium-ion batteries as well as hybrid super capacitor. Ithas good Li-ion insertion and extraction reversibility and displays a good structural stability withalmost negligible volume change in the charge/discharge processes. Li₄Ti₅O₁₂offers a convenientvoltage-plateau at （1.5V versus Li+/Li） which is higher than that of carbon, Most of theelectrolytes and organic solvents may stabilize since the reduction of electrolytes rarely occur atsuch a high potential. Therefore spinel lithium titanate has attracted increasing attention as asuperior anode material for energy storage cells.However, Li₄Ti₅O₁₂suffers from the problem of poor capacity at high rate mainly due to itslow electronic conductivity（10-9S/cm）. In the process of charging and discharging, Li₄Ti₅O₁₂material is prone to generate a greater polarization under higher current density, which seriouslyaffects the charge-discharge efficiency, discharge rate and cycle performance of Li₄Ti₅O₁₂material.This limits the application of Li₄Ti₅O₁₂anode material in power battery.To solve the above problems, the main field of our research work are listed as follow:1. Zr-doped Li₄Ti₅O₁₂cathode material by a simple solid state method was carried out in thesecond chapter. Results showed that a right amount of Zr ion dopant could improve onelectrical conductivity performance of Li₄Ti₅O₁₂, The discharge capacity ofLi4Zr0.05Ti4.95O12at0.1C reaches158.6mAh/g, and the capacity retention is97.6%after50cycles. 2. Li₄Ti₅O₁₂/C anode materials were fabricated by gel-casting method.Optimum amount ofPAM could regulate and control the grain growth of Li₄Ti₅O₁₂particles in the calcinationprocess. So it can reduce the particle size, thereby enhancing the material tap density. Thisway is a very good solution to the issue of a small proportion of Li₄Ti₅O₁₂materials.3. Mg-doped Li₄Ti₅O₁₂/C anode materials were fabricated by gel-casting method. Resultsshowed that the charge/recharge capacity and cycling performance of Li₄Ti₅O₁₂/C wasimproved by doping with Mg2+,among the doped LixMgyTi5O12/C anode materials,Li3.95Mg0.05Ti5O12/C（nLi: nMg=80:1） displayed the best electrochemical performance.4. The sphere and porous Li₄Ti₅O₁₂/C material was prepared by spray drying based ongel-casting method. This spray drying method could be easily used on a large scaleproduction of the sphere and porous Li₄Ti₅O₁₂/C material. The partical diameters of theas-prepared material were range from200nm to10μm measured by SEM and TEM. Resultsshowed that the sphere and porous Li₄Ti₅O₁₂/C material had better electrochemicalperformance, which demonstrated that morphology have an effect on performance. At thesame time, we found that the best additive amount of AM was15wt%of LTO.5. Metal-doped LTO was sythetized by spray drying based on gel-casting method.Themicrospheres of Li₄Ti₅O₁₂/C by Spray drying based on Gel-casting Method canimprove its Electrochemical performance and rate capability of Lithium-ionbattery.