Improvement of the Cycling Stability of Li-Rich Layered Mn-Based Oxide Cathodes Modified by Nanoscale LaPO4 Coating

Surface modification is usually an effective strategy to improve the cycling stability and rate capability of the Li-rich layered oxide cathode materials. Herein, the high-crystallinity LaPO4 with good ionic conductivity was homogeneously deposited on the surface of Li-rich layered oxide by the slow formation of LaPO4 nanoparticles because of chelating effect between citric acid and La3+ as well as the using of appropriate phosphorus source. The surface structure and electrochemical properties of Li-rich Mn-based materials were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), and galvanostatic charge/discharge tests. The results indicate that LaPO4 nanoparticles are homogeneously coated on the surface of Li-rich layered Mn-based oxide, and the modification of LaPO4 with appropriate nanoscale thickness can obviously promote the cycling stability and rate capability of cathode material. Especially, the material modified by 2 wt % LaPO4 shows an optimum cycling stability with capacity retention of 83.2% after 200 cycles at 1 C, the best structure stability, and delivers a discharge capacity of 146.2 mAh g(-1) even at a high current density of 10 C.