Synthesis by citric acid sol-gel method and electrochemical properties of Li4Ti5O12 anode material for lithium-ion battery

Spinel Li4Ti5O12 particles have been synthesized by a sol-gel method with citric acid as a chelating agent and Li2CO3 and tetrabutyl titanate (Ti(OC4H9)4) as starting materials. The samples have been characterized by means of IR, XRD, XPS and SEM. These analyses indicated that the prepared Li-Ti-O powder belonged to a spinel structure and had a uniform cubic morphology with an average particle size of 500 nm. Citric acid has a great effect on obtaining excellent phase purity and good stoichiometric inorganic oxides. Its electrochemical behavior was evaluated in a liquid electrolyte in lithium-ion batteries. At a voltage plateau located at 1.55 V(versus Li), the Li4Ti5O12 electrode exhibited an initial discharge capacity of 167 mAh g-1 and a subsequent charge capacity of 151 mAh g-1. The very flat discharge and charge curves indicated that the electrochemical reaction based on Ti4+/Ti3+redox couple was a typical two-phase reaction. The results of cyclic voltammetry for Li4Ti5O12 showed that at the potential range from 1.5 to 1.7 V (versus Li), there was a pair of reversible redox peaks correspond to the process of Li+ intercalation and de-intercalation in the spinel Li-Ti-O oxides