Effect of thermal treatment used in the sol–gel synthesis of Li4Ti5O12 spinel on its electrochemical properties as anode for lithium ion batteries

• High purity Li4Ti5O12 spinel has been synthesized by sol–gel after optimization of the thermal treatment.
• Annealing time and calcination temperature greatly modified the morphological properties of Li4Ti5O12.
• The electrochemical properties of the Li4Ti5O12 electrodes are explained based on their morphological features.
• Li4Ti5O12 spinel calcined at 900 °C for 1 h exhibits the best electrochemical performances.

The effect of the gel-drying temperature, annealing time at 900 °C and calcination temperature used in the sol–gel synthesis of Li4Ti5O12 spinel (LTO) on the purity phase, structural and morphological features, and electrochemical properties has been investigated. Synthesized LTO-samples have been characterized by X-ray diffraction and scanning electron microscopy (FE-SEM). High purity LTO-spinels have been synthesized by adjusting the thermal treatment conditions. The rate capability and cycleability of the LTO-samples have been studied by galvanostatic techniques in Li-half cells. The influence of the gel-drying temperature on the LTO-phase purity has been clearly evidenced. Both annealing time and calcination temperature notably modify the morphological features as the particle size, the agglomeration of the particles and its porosity. All the studied LTO-samples show a similar evolution of the capacity vs current in the rate capability test. Cycling studies have shown that LTO-samples exhibit high reversibility. Among the sol–gel synthesized LTO-spinels that prepared after drying the gel precursor at 150 °C, and then annealed at 550 °C for 6 h and 900 °C for 1 h shows the best electrochemical performances. It nominal capacity is 165 m Ah/g and it has a reversible capacity of 87 mA h/g at 1 C (175 mA/g) with no capacity fading after 100 cycles.