Dual functions of zirconium metaphosphate modified high-nickel layered oxide cathode material with enhanced electrochemical performance

High-nickel LiNi0.9Co0.1O2 cathode shows an enormous potential in next-generation high energy density lithium-ion batteries. However, its cation mixing and the second hexagon to the third hexagonal of phase transition (H2 - H3) pose severe challenges to its practical and commercial applications. In this work, zirconium metaphosphate is applied to optimize the microstructure near surface zone of LiNi0.9Co0.1O2 cathode material to suppress its cation mixing and the H2 - H3 phase transformation during long cycling process. It is found that single-atom or atomic group plays different roles in doping strategy due to their different thermodynamic properties. Specifically, Zr4+ tends to form a uniform doping to optimize crystal structure, while PO43- group presents a gradient distribution near the surface area and generates Li3PO4 coating layer to enhance the Li+ mass transfer. As a result, the modified LiNi0.9Co0.1O2 cathode shows an improved cycling stability with a high capacity retention of 93.7% after 100 cycles, whereas the bare LiNi0.9Co0.1O2 cathode only delivers a low capacity retention of 81.7%. This work highlights the critical role of thermodynamic properties of doped atoms toward the electrochemical performance and can be extended to other layered cathode materials.