Effect of Nb-doping on electrochemical stability of Li4Ti5O12 discharged to 0 V

Li4Ti4.95Nb0.05O12 is synthesized by a citric acid-assistant sol-gel method. X-ray diffraction (XRD) reveals that highly crystalline Li4Ti4.95Nb0.05O12 without any impurity is obtained. The electrochemical performances of the Li4Ti4.95Nb0.05O12 and the Li4Ti5O12 in the range from 0 to 2.5 V are investigated. The Li4Ti4.95Nb0.05O12 presents a higher specific capacity and better cycling stability than the Li4Ti5O12 due to the improved conductivity. The Li4Ti4.95Nb0.05O12 exhibits a capacity as high as 231.2 mAh g(-1) after 100 cycles, which is much higher than the Li4Ti5O12 (111.1 mAh g(-1)). The effect of Nb-doping on electrochemical performance of Li4Ti5O12 discharged to 0 V has also been discussed.