The storage properties of LiNi0.8Co0.15Al0.05O2 and LiCoO2-coated LiNi0.8Co0.15Al0.05O2 have been investigated comparatively. It is found that the latter exhibits better storage stability than the former. After storage in air at different relative humidities, LiCoO2-coated LiNi0.8Co0.15Al0.05O2 shows little changes in the aspects of weight, nickel oxidation state, moisture and carbon contents and electrochemical performance. However, for LiNi0.8Co0.15Al0.05O2, the higher the air humidity is, the bigger these aspects change. Fourier transformed infrared (FTIR) spectrum reveals that LiCoO2-coated LiNi0.8Co0.15Al0.05O2 is resistant to H2O and CO2 in air. X-ray photoelectron spectroscopy gives evidence that the LiCoO2 coating layer suppresses effectively the reactions between LiNi0.8Co0.15Al0.05O2 and atmosphere, which contributes to the enhancement of storage performance of LiCoO2-coated LiNi0.8Co0.15Al0.05O2.