锂离子电池正极材料铌掺杂LiNiO2 的制备与电化学性能

为了提高LiNiO₂的电化学性能，用固相反应法制备了铌掺杂LiNiO₂材料，并用X射线衍射（XRD）分析、恒电流滴定技术（GITT）、电化学阻抗谱（EIS）等方法研究铌掺杂量对LiNiO₂的结构和性能的影响。结果表明适量的铌（Nb）掺杂可以提高LiNiO₂层状结构的有序程度，降低Li⁺/Ni²⁺混合程度，降低电荷转移阻抗，提高活性材料中锂离子的扩散系数。其中LiNi_0.99Nb_0.01O₂在0.5C循环100次的容量保持率为91.4%，5C时放电比容量为143 mA·h/g。而未掺杂铌的LiNiO₂在相同条件下的容量保持率和比容量仅为69.2%和127 mA·h/g。结果说明铌掺杂能够有效提高LiNiO₂的电化学性能。

Preparation and electrochemical performance of Nb-doped LiNiO2 cathode material for lithium-ion batteries

In order to improve the performance of LiNiO₂，Nb-doped LiNiO₂ was prepared by a solid-state reaction method.The effects of the amount of Nb-doping on the structure and performance of LiNiO₂ were investigated by X-ray diffraction analysis（XRD），galvanostatic titration（GITT），electrochemical impedance spectroscopy（EIS） and other methods.Nb-doping could effectively improve the order degree of the layered structure，reduce Li⁺/Ni²⁺ mixing，reduce the charge transfer impedance，and increase the diffusion coefficient of Li⁺ in the active materials.Therefore，LiNi_0.99Nb_0.01O₂ exhibited higher capacity retention（91.4% after 100 cycles at 0.5C） and better rate capability（143 mA·h/g at 5C）.As a comparison，the data of bare LiNiO₂ was 69.2% and 127 mA·h/g under the same conditions.These results further demonstrated that Nb-doping with a strong Nb—O bond，high valence stat，and larger ionic radius could effectively improve the performance of LiNiO₂.