Improving the Cycling Stability of Li-Rich Mn-Based Cathodes through Surface Modification of VOPO4

Li-rich layered Mn-based oxide cathode materials (LLO) are the most promising next-generation cathode materials of Li-ion batteries (LIBs). However, the fundamental challenges faced in the development of LLO include the low initial Coulombic efficiency (ICE), serious capacity fading, and voltage decay during the cycling process. Surface modification is usually one of the effective methods for overcoming the above shortcomings and promoting their performances. In this study, we propose a facile and valid strategy to modify the Li1.2Mn0.54Ni0.13Co0.13O2 by VOPO4 with good ionic conductivity and high-crystallinity. It has been found that the VOPO4 coating layer can not only reduce the content of surface residual Li+ but also inhibit structural degradation of LLO. At the same time, VOPO4 can inhibit the escape of O2 molecules from LLO during the charge/discharge process, thus improving the electrochemical performances. Accordingly, the as-prepared Li1.2Mn0.54Ni0.13Co0.13O2@VOPO4 sample modified by 3 wt % VOPO4 exhibits an initial discharge capacity of 260.5 mAh g–1 with an initial Coulombic efficiency (99.57%) at a rate of 0.1 C and a good discharge capacity retention of 92% after 100 cycles at 1 C.