Sol–gel synthesis of aluminum doped lithium titanate anode material for lithium ion batteries

Highlights: ► Li4Ti5−xAlxO12 (x = 0, 0.05) materials were synthesized by a facile sol–gel process. ► Superior rate capability can be demonstrated for the Li4Ti4.95Al0.05O12 materials. ► Improved rate capability can be ascribed to the enhancement of conductivities. ► Reversible capacity was increased at least 50 mAh g−1 when discharged to 0 V. ► Almost no irreversible capability was observed when discharged to 0 V. - Abstract: In this study, spinel Li4Ti5−xAlxO12 (x = 0, 0.05) materials were successfully synthesized by a simple and facile sol–gel process. The characteristics of the as-prepared Li4Ti5−xAlxO12 (x = 0, 0.05) were examined by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electronic microscopy, while the electrochemical performances including charge/discharge test, cyclic voltammetry, and electrochemical impedance spectroscopy were also investigated. Li4Ti4.95Al0.05O12 electrode demonstrated the superior initial discharge capacity and rate capability to Li4Ti5O12 electrode cycled between 1.0 and 2.5 V or between 0 and 2.5 V. The enhanced rate capability can be attributed to the higher Li+ diffusivity and lower charge-transfer resistance due to the substitution of Al3+for Ti4+. Moreover, when both electrodes discharged to 0 V, the reversible capacities were further increased ∼50 mAh g−1 with excellent cycling stability and almost no irreversible capability was observed during cycling.