Microsized TiO2 activated by high-energy ball milling was used as starting material to synthesize spinel Li4Ti5O12 by a conventional solid-state method. The effects of TiO2 particle size on the structure, morphology and electrochemical performance of Li4Ti5O12 were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and electrochemical tests. The results indicate that the particle size and degree of crystallinity of TiO2 are significantly reduced by the mechanical activation of high-energy ball milling. The crystalline structure and morphology of Li4Ti5O12 highly depend on the properties of TiO2. The optimal Li4Ti5O12 sample exhibits a high rate capability of about 103.9 mAh/g at 10C rate and excellent cyclability at 1C rate, which could be ascribed to the smaller particle size and higher lithium-ion diffusion coefficient. Therefore, the microsized TiO2 activated by high-energy ball milling is suitable for the economic synthesis of Li4Ti5O12. (C) 2013 Elsevier B.V. All rights reserved.