A Facile Li2TiO3 Surface Modification to Improve the Structure Stability and Electrochemical Performance of Full Concentration Gradient Li-Rich Oxides

Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage, reduced voltage decay and enhanced rate performance, whereas the high lithium residues on its surface impairs the structure stability and long-term cycle performance. Herein, a facile multifunctional surface modification method is implemented to eliminate surface lithium residues of full concentration gradient lithium-rich layered oxides by a wet chemistry reaction with tetrabutyl titanate and the post-annealing process. It realizes not only a stable Li2TiO3 coating layer with 3D diffusion channels for fast Li+ ions transfer, but also dopes partial Ti4+ ions into the sub-surface region of full concentration gradient lithium-rich layered oxides to further strengthen its crystal structure. Consequently, the modified full concentration gradient lithium-rich layered oxides exhibit improved structure stability, elevated thermal stability with decomposition temperature from 289.57 degrees C to 321.72 degrees C, and enhanced cycle performance (205.1 mAh g(-1) after 150 cycles) with slowed voltage drop (1.67 mV per cycle). This work proposes a facile and integrated modification method to enhance the comprehensive performance of full concentration gradient lithium-rich layered oxides, which can facilitate its practical application for developing higher energy density lithium-ion batteries.