CaF2 Coated Li1.2Mn0.56Ni0.16Co0.08O2 Microspheres with Enhanced Electrochemical Performances as Lithium Ion Battery Cathode

Surface modification has been one of most effective methods to improve the electrochemical performance of lithium rich layered oxides. In this paper, the Li1.2Mn0.56Ni0.16Co0.08O2 microspheres are prepared by urea assisted combustion route, and then coated with proper amount of CaF2. XRD and SEM results show surface modification has not changed the structure of Li1.2Mn0.56Ni0.16Co0.08O2, and a uniform coating layer can be obtained. As lithium ion battery cathode, the optimal CaF2 (i.e, 2 wt.%) coated sample presents a high initial discharge capacity of 223 mAh.g(-1) with Coulombic efficiency of 80.5 % at 0.1 C, which is much better than that of pristine sample. Also, a high discharge capacity of 119 mAh.g(-1) can be obtained for CaF2 coated sample at 5 C. The improved electrochemical performance may be attributed the formation of fast Li ion conductor on the surface supported by EIS study.