Submicron-sized Li4Ti5O12/Li2TiO3 composites with Li-rich grain boundaries are successfully synthesized by a simple, environmentally benign, mass production preferred solid state process. The crystal phase and morphology are characterized by XRD and SEM. The electrochemical performance is collected by galvanostatic discharge-charge tests, cyclic voltammograms (CV) and electrochemical impedance spectra (EIS) tests. The initial discharge capacity of Li4Ti5O12/Li2TiO3 composite is 155 mAh g(-1) at 0.5 C. While the current rate is as high as 10 degrees C, the specific capacity is 113 mAh g(-1), and the capacity retention is 98.2% even after 500 cycles. As a reference, the ionic conductivity and the electrochemical performance of Li2TiO3 and Li4Ti5O12/TiO2 composite are also characterized. The extraordinary high rate performance and cycling stability are explained by high ionic conductivity and rich grain boundaries of Li4Ti5O12/Li2TiO3 composite. (C) 2014 Elsevier B.V. All rights reserved.