High-performance Li4Ti5−xVxO12 (0 ≤ x ≤ 0.3) as an anode material for secondary lithium-ion battery

Powders of spinel Li4Ti5−xVxO12 (0 ≤ x ≤ 0.3) were successfully synthesized by solid-state method. The structure and properties of Li4Ti5−xVxO12 (0 ≤ x ≤ 0.3) were examined by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electronic microscope (SEM), galvanostatic charge–discharge test and cyclic voltammetry (CV). XRD shows that the V5+ can partially replace Ti4+ and Li+ in the spinel and the doping V5+ ion does almost not affect the lattice parameter of Li4Ti5O12. Raman spectra indicate that the Raman bands corresponding to the Li–O and Ti–O vibrations have a blue shift due to the doping vanadium ions, respectively. SEM exhibits that Li4Ti5−xVxO12 (0.05 ≤ x ≤ 0.25) samples have a relative uniform morphology with narrow size distribution. Charge–discharge test reveals that Li4Ti4.95V0.05O12 has the highest initial discharge capacity and cycling performance among all samples cycled between 1.0 and 2.0 V; Li4Ti4.9V0.1O12 has the highest initial discharge capacity and cycling performance among all samples cycled between 0.0 and 2.0 V or between 0.5 and 2.0 V. This excellent cycling capability is mainly due to the doping vanadium. CV reveals that electrolyte starts to decompose irreversibly below 1.0 V, and SEI film of Li4Ti5O12 was formed at 0.7 V in the first discharge process; the Li4Ti4.9V0.1O12 sample has a good reversibility and its structure is very advantageous for the transportation of lithium-ions.