摘要
Pristine LiNi_（0.5）Mn_（1.5）O_4 and cerium doped LiCe_xNi_（0.5–x）Mn_（1.5）O_4（x=0.005, 0.01, 0.02） cathode materials were synthesized by solid-state method. The effect of Ce doping content on structure and electrochemical properties of LiNi_（0.5）Mn_（1.5）O_4 cathode material was systematically investigated. The samples were characterized by X-ray diffraction（XRD）, Fourier transformation infrared spectrometer（FT-IR）, scanning electron microscopy（SEM）, electrochemical impedance spectroscopy（EIS）, cyclic voltammetry（CV） and constant-current charge/discharge tests. The results showed that Ce doping did not change the cubic spinel structure with Fd3m space group, but effectively restrained the formation of Li_xNi_（1–x）O impurity phase. Appropriate Ce doping（x=0.005） could decrease the extent of confusion between lithium ions and transition metal ions, increase the lattice parameter and Ni/Mn disordering degree（Mn^（3＋） content）. The synergic effects of the above factors led to the optimal electrochemical performance of LiCe_（0.005）Ni_（0.495）Mn_（1.5）O_4 sample. The discharge capacity at 10 C rate could reach 115.4 mAh/g, 94.82% of that at 0.2C rate, and the capacity retention rate after 100 cycles at 1C rate could reach 94.51%. However, heavier Ce doping had an adverse effect on the electrochemical properties, which might be due to the lower disordering degree and existence of more CeO_2 secondary phase.
Pristine LiNi_（0.5）Mn_（1.5）O_4 and cerium doped LiCe_xNi_（0.5–x）Mn_（1.5）O_4（x=0.005, 0.01, 0.02） cathode materials were synthesized by solid-state method. The effect of Ce doping content on structure and electrochemical properties of LiNi_（0.5）Mn_（1.5）O_4 cathode material was systematically investigated. The samples were characterized by X-ray diffraction（XRD）, Fourier transformation infrared spectrometer（FT-IR）, scanning electron microscopy（SEM）, electrochemical impedance spectroscopy（EIS）, cyclic voltammetry（CV） and constant-current charge/discharge tests. The results showed that Ce doping did not change the cubic spinel structure with Fd3m space group, but effectively restrained the formation of Li_xNi_（1–x）O impurity phase. Appropriate Ce doping（x=0.005） could decrease the extent of confusion between lithium ions and transition metal ions, increase the lattice parameter and Ni/Mn disordering degree（Mn^（3＋） content）. The synergic effects of the above factors led to the optimal electrochemical performance of LiCe_（0.005）Ni_（0.495）Mn_（1.5）O_4 sample. The discharge capacity at 10 C rate could reach 115.4 mAh/g, 94.82% of that at 0.2C rate, and the capacity retention rate after 100 cycles at 1C rate could reach 94.51%. However, heavier Ce doping had an adverse effect on the electrochemical properties, which might be due to the lower disordering degree and existence of more CeO_2 secondary phase.
基金
supported by the Natural Science Foundation of Hebei Province(E2015202356)
Key R&D Plan Self-raised Project of Hebei Province(16214406)
Technology Innovation Foundation Project for Outstanding Youth of Hebei University of Technology(2013009)
