Improvement of Electrochemical Properties of Surface Modified
Li_1.05Ni_0.35Co_0.25Mn_0.4O₂ Cathode Material for Lithium Secondary Battery

摘要

In this study, nano-crystallized LiCoO2 was coated on the surface of Li1.05Ni0.35Co0.25Mn0.4O2 powders via sol-gel method. The influence of coated Li1.05Ni0.35Co0.25Mn0.4O2 about electrochemical behavior was discussed. The surface morphology characterization was achieved by transmission electron microscopy (TEM). Nano-crystallized LiCoO2 was clearly observed on the surfaces of Li1.05Ni0.35Co0.25Mn0.4O2. It showed that LiCoO2 coated Li1.05Ni0.35Co0.25Mn0.4O2 cathode exhibited distinct surface morphology. Cyclic voltammertry (2.8-4.6 V) shows that the characteristic voltage transition on cycling exhibited by the bare compound are suppressed by 5 wt% LiCoO2 coating. This behavior implies that LiCoO2 prevent structural change of Li1.05Ni0.35Co0.25Mn0.4O2 or reaction with electrolyte on cycling. In addition, LiCoO2 coated Li1.05Ni0.35Co0.25Mn0.4O2 compound shows highly improved area-specific impedance (ASI), one of the important battery performances. From the correlation between these characteristics of bare and coated Li1.05Ni0.35Co0.25Mn0.4O2, the role of LiCoO2 coating played on the electrochemical performance of Li1.05Ni0.35Co0.25Mn0.4O2 was probed.