Effect of AIF3 coating amount on high voltage cycling performance of LiCoO2

The effect of AIF(3) coating amount on the electrochemical cycling behavior of the LiCoO2 Positive electrode was investigated at the high upper voltage limit of 4.5 V. The cycling performance and rate capability of LiCoO2 positive electrode are strongly related with the amount of AIF(3) coating. The electrochemical performance of the AIF(3)-coated LiCoO2 decreased with increasing AIF(3) coating amount but showed enhanced properties, compared to those of pristine material. The 0.5 mol% AIF(3)-coated LiCoO2 had the best electrochemical performance, showing capacity retention of 97.7% after 50 cycles and rate capability of 93.1 % at 5 C discharge. Electrochemical impedance spectroscopy (EIS) and differential capacity (dQ dV(-1)) suggested that the AIF(3) coating plays an important role in stabilizing the positive electrode/electrolyte interface and the host structure. (C) 2007 Elsevier Ltd. All rights reserved.