Robust Strategy for Crafting Li 5 Cr 7 Ti 6 O 25 @CeO 2 Composites as High-Performance Anode Material for Lithium-Ion Battery.

A facile strategy was developed to prepare Li5 Cr7 Ti6 O25 @CeO2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO2 coating does not alter the structure of Li5 Cr7 Ti6 O25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO2 layer successfully formed a coating layer on a surface of Li5 Cr7 Ti6 O25 particles and supplied a good conductive connection between the Li5 Cr7 Ti6 O25 particles. The electrochemical characterization reveals that Li5 Cr7 Ti6 O25 @CeO2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li5 Cr7 Ti6 O25 @CeO2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li5 Cr7 Ti6 O25 only delivers an initial delithiation capacity of ∼94.7 mAh g-1 , and the delithiation capacity merely achieves 87.4 mAh g-1 even after 100 cycles. However, Li5 Cr7 Ti6 O25 @CeO2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g-1 , and the delithiation capacity also reaches 100.5 mAh g-1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li5 Cr7 Ti6 O25 at large current densities.