Development Of Lithium Titanate As The Negative Materials For Lithium Ion Batteries

Lithium Titanate was synthesized by solid-state reaction and sol-gel method, respectively. The materials were investigated by constant current charge-discharge test, AC impedance, Cycle Voltammagram (CV) and characterized by X-ray Diffraction (XRD), Scan electron microscope (SEM), Thermogravimetry-differential thermoanalysis (TG-DTA).The infection of the synthesis conditions of Li₄Ti₅O₁₂ prepared by solid-state reaction were investigated, CV and AC impedance were used to evaluate the product. The results demonstrated that the materials of best performance were prepared with Li2CO3 and anatase TiO2 as starting materials sintered at 900℃for 16h. There is not passivation film on the surface of Li₄Ti₅O₁₂ indicated that Li₄Ti₅O₁₂ was safer than carbon as Li-ion battery negative material.Solid-state reaction was used to gain ion-doped Li₄Ti₅O₁₂. The results showed that the ions of Ag⁺,V⁵⁺,Sn⁴⁺,Mo⁶⁺,Ge⁴⁺,Nb⁵⁺ were doped availably. The materials doped by Ag⁺,Sn⁴⁺,Mo⁶⁺,Ge⁴⁺ got best performance with different doping content: 0.2 Ag⁺ with 140.89mAh/g discharge capacity after 20cycles at 0.2C, 0.1 Sn⁴⁺ with 157.10mAh/g discharge capacity after 20cycles at 0.1C, 0.2 Mo⁶⁺ with 145.86 mAh/g discharge capacity after 20cycles at 0.2C, 0.1 Ge4+ with174.38mAh/g first discharge capacity 156.86mAh/g discharge capacity after 20 cycles at 0.1C.Li₄Ti₅O₁₂ was synthesized by sol-gel method, different operation ans sintered time were investigated to get the ideal experimental flow. The results showed that the materials sintered at 900℃for 20h got the capacity of 120mAh/g and better high charge-discharge efficiency. Mo⁶⁺,Nb⁵⁺,Ge⁴⁺ could also be doped by sol-gel method, the material doped with 0.5 Mo⁶⁺ was better than other doped. The cyclic stability of doped Li₄Ti₅O₁₂ was improved than pure Li₄Ti₅O₁₂.