Co掺杂改性尖晶石型Li1.035Mn1.965O4的合成及其电化学性能

Spinel powders of Li1.035CoxMn1.965-xO4 (x=0-0.100) systems were synthesized by a simple wet chemical process with post heat-treatment. X-ray diffraction patterns (XRD) reveal that the Co doping does not affect the Fd3m space group of the cathode materials. Scanning electron microscope (SEM) images show that the Li1.035CoxMn1.965-xO4 cathode materials have a uniform and nearly cubic morphology with a narrow size distribution. Transmission electron microscope (TEM) results demonstrate that the Li1.035Co0.035Mn1.930O4 powder has a good crystalline state. The electrochemical testing results indicate that the prepared Co-doped Li1.035CoxMn1.965-xO4 samples show a better cycling ability and rate capability at room temperature than that of Co-free Li1.035Mn1.965O4. In particular, the Li1.035 Co0.035Mn1.930O4 sample delivers a reversible specific capacity of 113 mAh/g in 1 st cycle and retains 93.8% of its initial capacity after 100 cycles at 0.5C rate. When discharging at 4C rate, the Li1.035Co0.035Mn1.930O4 powder maintains 86 mAh/g, which is 76.1% of the reversible capacity at 0.5C. Comparatively, the Li1.035Mn1.965O4 powder maintains only 64.8% of its reversible capacity at 0.5C discharge rate. The electrochemical impedance spectroscopy results show that Co ion doping can enhance the electrical conductivity and the Li-ion diffusion coefficient. These results indicate a superior cycling and rate performance compared with the pristine one.