Novel spinel Li 5 Cr 9 Ti 4 O 24 anode: Its electrochemical property and lithium storage process

High-performance Li-ion battery driven by a hybrid Li storage mechanism in a three-dimensional architectured ZnTiO3-CeO2 microsphere anode

ZnTiO₃ and ZnTiO₃-CeO₂ microspheres with particle sizes of about 100-300 nm were synthesized for the first time by a simple solvothermal process followed by calcination. The results indicate that CeO₂ modification does not alter the morphology of the microspheres. ZnTiO₃-CeO₂ (0, 3, 6, and 9 wt%) show an initial charge (discharge) capacity of 171.01 (253.2), 204.6 (507.5), 213.4 (451.6) and 126.2 (367.2) mA h g^-1 at 500 mA g^-1, respectively. After 500 cycles, the corresponding charge (discharge) capacities were 191.1 (192.3), 298.7 (300.3), 322.4 (328.5) and 211.2 (212.3) mA h g^-1, respectively. Obviously, the charge (discharge) capacities of the ZnTiO₃-CeO₂ composites are superior to those of pristine ZTO, which demonstrates that the Li storage performance of the CeO₂-modified ZTO electrodes is improved. The CeO₂ shell provides a good electronic contact between ZnTiO₃ and CeO₂, decreasing charge transfer resistance and facilitating the charge transportation of the ZnTiO₃-CeO₂ composite. In addition, the formed phase interface between CeO₂ and ZnTiO₃ may provide more active sites for electrochemical reactions, improving the reversibility of Li-ion intercalation and decreasing the electrochemical polarization during cycling, especially at high current densities. Therefore, such ZnTiO₃-CeO₂ microspheres can be regarded as hopeful candidates for anode materials for Li-ion batteries.

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.