LiNi1/3Co1/3Mn1/3O2 coated with nano-particle AlF3 as cathode material for Li-ion batteries

摘要

LiNi1/3Co1/3Mn1/3O2 coated with nano-particle AlF3 was prepared by chemical precipitation method in this paper to improve its electrochemical performance. The bare and coated materials were characterized by X-ray diffraction (XRD), scanning electron macroscopy (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge-discharge cycling. XRD results showed that the material still kept a layered structure with space group R-3m and a uniform coated layer about 3nm were observed by TEM. The coated LiNi1/3Co1/3Mn1/3O2/Li with 0.5C-rate at 60.C showed nearly no fade capacity after 50 cycles, while that of bare one reached 21.4%. As for high voltage (4.7V) cyclic performance at 0.2C-rate, the discharged capacity of the bare one after 20 cycles was 28 mAh/g, only 15.2% of initial discharged capacity, however, 121.4 mAh/g of the coated one was retained. Based on the cyclic voltammetry results, we considered that the thin AlF3 layer on LiNi1/3Co1/3Mn1/3O2 could lower the activity of interface between active material and electrode by introducing the strong Al-F bonds on the electrode surface, which would protect the active material and suppress the decomposition of electrolyte obviously.