Preparation and Characterization of Ge4+-doping Li4Ti5O12 Anode Material for Li-ion Battery and Its Electrochemical Properties

The spinel Li4Ti5-xGexO12 (x=0, 0.05, 0.1, 0.15) electrode materials were successfully synthesized by Sol-Gel method using Ti(OC4H9)(4), CH3COOLi center dot 2H(2)O and GeO2 as raw materials. The crystalline structure, morphology and electrochemical properties of the obtained materials were characterized by XRD, SEM, half cell charge-discharge tests, cyclic voltammetry (CV) and AC impedance. The results showed that doping with certain amount of Ge4+ did not change the basic structure of Li4Ti5O12, but greatly affected its mophology and particle size. Ge-doped Li4Ti5O12 has relatively high rate capability due to the smaller particle size. In this study, Li4Ti4.9Ge0.1O12 represented the highest initial discharge capacity and the best cycling performance among all samples. At the charge-discharge rate of 0.2C, its first discharge capacity was 172.43 mAh/g, and at 5C rate, its discharge capacity remained at 140.62 mAh/g after 100 cycles with a capacity retention of 97.3%.