Reinforcing the surface conductivity and stability of primary particles for high-performance Li-rich layered Li1.18Mn0.52Co0.15Ni0.15O2 via an integrated strategy

A Li-rich layered oxide of Li1.18Mn0.52Co0.15Ni0.15O2 with Li3PO4 as an outer modification layer and a spinel as an inner modification layer on the surface of the primary particles was synthesized by a facile synchronous method. A series of physical characterization techniques indicate that the Li3PO4 and spinel simultaneously form not only on the surface but also in the bulk of the cathode material during the preparation process. Consequently, a stable protective layer and a highly conductive interlayer are fabricated by the formation of the Li3PO4 and spinel phase on the primary particle surface of the cathode material. The modified sample exhibits an improved initial coulombic efficiency of approximately 88.5%. Moreover, the capacity retention of the modified sample increases to 92% after 100 cycles at a rate of 0.2 C from 2.0-4.8 V compared to that of the pristine sample (62.7%). Moreover, the modified sample also exhibits an excellent rate capability of 171.4 mAh g-1 at the 5 C rate relative to that of the pristine sample (134.1 mAh g-1). Our facile modification approach combines the merits of the spinel phase and Li3PO4 compound. Also, our approach can remarkably suppress the structural transformation from layered to spinel-like and decrease the loss of active material by mitigating the formation of corrosion pits on the particles as well as enhance the dynamic performance of Li+ diffusion of Li-rich layered oxide.