RESUMEN
Li-rich Mn-based oxides (LRMOs) are considered as one of the most-promising cathode materials for next generation Li-ion batteries (LIBs) because of their high energy density. Nevertheless, the intrinsic shortcomings, such as the low first coulomb efficiency, severe capacity/voltage fade, and poor rate performance seriously limit its commercial application in the future. In this work, we construct successfully g-C3N4 coating layer to modify Li1.2Mn0.54Ni0.13Co0.13O2 (LMNC) via a facile solution. The g-C3N4 layer can alleviate the side-reaction between electrolyte and LMNC materials, and improve electronic conduction of LMNC. In addition, the g-C3N4 layer can suppress the collapse of structure and improve cyclic stability of LMNC materials. Consequently, g-C3N4 (4 wt%)-coated LMNC sample shows the highest initial coulomb efficiency (78.5%), the highest capacity retention ratio (78.8%) and the slightest voltage decay (0.48 V) after 300 loops. Besides, it also can provide high reversible capacity of about 300 and 93 mAh g-1 at 0.1 and 10C, respectively. This work proposes a novel approach to achieve next-generation high-energy density cathode materials, and g-C3N4 (4 wt%)-coated LMNC shows an enormous potential as the cathode materials for next generation LIBs with excellent performance.
RESUMEN
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.