Improved electrochemical properties of Li4Ti5O12-Li0.33La0.56TiO3 composite anodes prepared by a solid-state synthesis

Li4Ti5O12-Li0.33La0.56TiO3 composite anodes are successfully prepared by a facile solid state route. The structure, morphology and electrochemical performance of all samples are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests, respectively. XRD reveals that the little La3+ ions enter into the lattice, and then make the crystal lattice of Li4Ti5O12 expand. SEM shows that all samples are composed of 1-2 mm primary particles with irregular shapes. CV and EIS imply that Li4Ti5O12-Li0.33La0.56TiO3 composites have lower polarization, larger lithium-ion diffusion coefficient and smaller charge transfer resistance corresponding to a much higher conductivity than those of Li4Ti5O12 corresponding to the extraction of Li+ ions. The improved electrochemical performance of Li4Ti5O12-Li0.33La0.56TiO3 composites can be attributed to the enhanced transfer kinetics of both the lithium ions and electrons. Particularly, Li4Ti5O12-Li0.33La0.56TiO3 (5 wt.%) composite shows a excellent high-rate capability and cycling stability. Therefore, the present Li4Ti5O12-Li0.33La0.56TiO3 (5 wt.%) composite anode is capable of large-scale applications, such as electric vehicles and hybrid electric vehicles, requiring high energy, long life and excellent safety. (C) 2015 Elsevier B.V. All rights reserved.