Niobium doped lithium titanate as a high rate anode material for Li-ion batteries

Niobium doped lithium titanate with the composition of Li4Ti4.95Nb0.05O12 has been prepared by a sol–gel method. X-ray diffraction (XRD) and scanning electron microscope (SEM) are employed to characterize the structure and morphology of Li4Ti4.95Nb0.05O12. The Li4Ti4.95Nb0.05O12 electrode presents a higher specific capacity and better cycling performance than the Li4Ti5O12 electrode prepared by the similar process. The Li4Ti4.95Nb0.05O12 exhibits an excellent rate capability with a reversible capacity of 135 mAh g−1 at 10 C, 127 mAh g−1 at 20 C and even 80 mAh g−1 at 40 C. Electrical resistance measurement and electrochemical impedance spectra (EIS) reveal that the Li4Ti4.95Nb0.05O12 exhibits a higher electronic conductivity and faster lithium-ion diffusivity than the Li4Ti5O12, which indicates that niobium doped lithium titanate (Li4Ti4.95Nb0.05O12) is promising as a high rate anode for the lithium-ion batteries.