Electrochemical properties of nano-sized Li 4Ti 5O 12 powders synthesized by a sol-gel process and characterized by X-ray absorption spectroscopy

Nano-sized spinel Li ₄Ti ₅O ₁₂ powders were synthesized by a sol-gel process. The cubic spinel structure without impurity phase of the synthesized Li ₄Ti ₅O ₁₂ powders was confirmed by X-ray diffraction. The average grain size of the synthesized powders was found to be around 39 nm. In situ X-ray absorption spectroscopy (XAS) has been performed on the Li ₄Ti ₅O ₁₂ electrode to investigate its change in the oxidation state and the local environment of the electrode during charging and discharging processes. The X-ray absorption near edge spectroscopy (XANES) analysis showed that the absorption edge energy shifts towards lower and higher energy, respectively, during discharge and charge processes, indicating the reversibility of the electrode is quite good. It was worthy to note that the discharging capacity and the charging capacity obtained for the nano-sized Li ₄Ti ₅O ₁₂ electrode in the potential range of 0.01-1.75 V are 255 and 242 mAh g ^-1, respectively. However, the specific charge capacity obtained in the potential range of 1.0-2.0 V is 126 mAh g ^-1. The spinel Li ₄Ti ₅O ₁₂ electrode maintains the cubic spinel structure for repeated cycling resulting in good cyclability and the capacity retention.