Robust Strategy for Crafting Li₅Cr₇Ti₆O₂₅@CeO₂ Composites as High-Performance Anode Material for Lithium-Ion Battery

A facile strategy was developed to prepare Li₅Cr₇Ti₆O₂₅@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 Li₅Cr₇Ti₆O₂₅ 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 Li₅Cr₇Ti₆O₂₅ particles and supplied a good conductive connection between the Li₅Cr₇Ti₆O₂₅ particles. The electrochemical characterization reveals that Li₅Cr₇Ti₆O₂₅@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, Li₅Cr₇Ti₆O₂₅@CeO₂ (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li₅Cr₇Ti₆O₂₅ 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, Li₅Cr₇Ti₆O₂₅@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 Li₅Cr₇Ti₆O₂₅ at large current densities.