(Na、K、Rb)掺杂正极材料LiNiO2第一性原理研究

In this study, first-principles calculations based on density functional theory (DFT) and ab initio molecular dynamics (AIMD) were employed to investigate the electronic structure, structural stability, lithium-ion diffusion properties, and operating voltage of Li11MNi12O24 (M = Na、K、Rb). Doping with Na/K/Rb introduces impurity bands, reducing the band gap and enhancing the electrical conductivity of the system. With increasing atomic number of the dopant, the covalency of M-O bonds gradually decreases. After doping, the Li-O bond length in the system increases, weakening the chemical bond strength of Li-O, which facilitates lithium-ion diffusion. The lithium-ion diffusion barriers in Na/K/Rb-doped LiNiO2 are reduced from 0.996 eV (pristine LiNiO2) to 0.742 eV/0.542 eV/0.751 eV, respectively. The diffusion coefficient and diffusion rate of lithium ions in the doped system are at least three orders of magnitude larger than those in the intrinsic system. Additionally, the operating voltage of the system slightly decreases after doping. These results provide a reliable reference for identifying suitable alkali metal elements to improve the electrical conductivity and diffusion rate of lithium ions in LiNiO2, as well as enhance the structural stability of the system.