Li3PO4 modification on a primary particle surface for high performance Li-rich layered oxide Li1.18Mn0.52Co0.15Ni0.15O2via a synchronous route

Abstract

A Li-rich layered oxide, Li_1.18Mn_0.52Co_0.15Ni_0.15O₂, with Li₃PO₄ modification on the surface of a primary particle, was synthesized by a facile synchronous method. Physical characterization results indicate that the Li₃PO₄ simultaneously forms not only on the surface but also in the interior of the cathode material during the preparation process. Consequently, a stable protective layer, which also acts as a network of fast Li⁺ channels, was constructed by the formation of Li₃PO₄ on the primary particle surface of the cathode material. The modified sample exhibits an improved initial coulombic efficiency of approximately 86%. Moreover, the capacity retention of the modified sample increases by approximately 72% after 200 cycles at 1C rate between 2.0 and 4.8 V, compared to the pristine sample. Meanwhile, the modified sample delivers a discharge capacity as high as 178.4 mA h g⁻¹ at 5C rate. The excellent property of the modified sample can be attributed to the multifunctional Li₃PO₄ modification layer on the primary particle surface, which can remarkably restrain the side reactions between the primary particle and the electrolyte, and thus mitigate the formation of corrosion pits of the particle surface as well as suppress the structural transformation during long-term cycling. In addition, it can also enhance the dynamic performance of Li⁺ diffusion as a network of fast Li⁺ channels.