Effects of the starting materials and mechanochemical activation on the properties of solid-state reacted Li4Ti5O12 for lithium ion batteries

Li4Ti5O12 was synthesized by a solid-state reaction between Li2CO3 and TiO2 for applications in lithium ion batteries. The effects of the TiO2 phase and mechanochemical activation on the Li4Ti5O12 particles as well as the corresponding electrochemical properties were investigated. Rutile TiO2 was more desirable in acquiring high purity Li4Ti5O12 than anatase due to the anatase to rutile phase transformation, which was found to be more rigid in the solid-state reaction than the intact rutile phase. Mechanochemical activation of the starting materials was effective in decreasing the reaction temperature and particle size as well as increasing the Li4Ti5O12 content. The specific capacity depended significantly on the Li4Ti5O12 content, whereas the rate capability improved with decreasing particle size due to the enhanced contact area and reduced diffusion path. Overall, a 200 nm-sized Li4Ti5O12 powder with a specific capacity of 165 mAh/g could be synthesized by optimizing the milling method and starting materials.