LiNi1/3Mn1/3Co1/3O2 prepared by a spray drying method exhibited poor cyclic performance when it was operated at rates of 0.5C and 2C in 3-4.6 V. A metal oxide (ZrO2, TiO2, and Al2O3) coating (3 wt%) could effectively improve its cyclic performance at both 0.5C and 2C. Electrochemical impedance spectroscopy (EIS) studies suggested that both the surface resistance and the charge transfer resistance of the bare LiNi1/3Mn1/3Co1/3O2 significantly increase after 100 cycles, whose origin is mainly related to the change in both the particle surface and electrode morphologies. The presence of a thin metal oxide layer could remarkably suppress the increase in the total resistance (sum of the surface resistance and the charge transfer resistance), which was attributed to the improvement in good cyclic performances. (c) 2006 Elsevier B.V. All rights reserved.