Synthesis and characterization of LiCoO2-coated LiNi0.8Co0.15Al0.05O2 cathode materials

An electrochemically active LiCoO2 layer was coated onto the surface of LiNi0.8Co0.15Al0.05O2 by a molten salt method. The 3.0 wt.% LiCoO2-coated LiNi0.8Co0.15Al0.05O2 exhibited excellent electrochemical performance, with an initial discharge capacity of 196.2 mAh.g(-1) and capacity retention of 98.7% after 50 cycles when cycled at 0.2 C rate between 2.8 and 4.3 V. Moreover, the cycle performance and rate capability of the coated sample were better than that of the bare one. Electrochemical impedance spectroscopy measurements showed that the decrease of NiO-type surface layer on the coated sample is the major reason for the improvement of electrochemical performance of LiCoO2-coated LiNi0.8Co0.15Al0.05O2 cathode. (C) 2012 Elsevier B.V. All rights reserved.