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

High-nickel LiNi_0.9Co_0.1O₂ 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 LiNi_0.9Co_0.1O₂ 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 PO₄^3- 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 LiNi_0.9Co_0.1O₂ cathode shows an improved cycling stability with a high capacity retention of 93.7% after 100 cycles, whereas the bare LiNi_0.9Co_0.1O₂ 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.