The cathode-active materials, layered Li[Ni0.333Co0.333Mn0.293Al0.04]O2-zFz (0 <= z <= 0.1), were synthesized from a sol-gel precursor at 900 C in air. The influence of Al-F co-substitution on the structural and electrochemical properties of the as-prepared samples was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical experiments. The results showed that Li[Ni0.333Co0.333Mn0.293Al0.04]O2-zFz has a typical hexagonal structure with a single phase, the particle sizes of the samples tended to increase with increasing fluorine content. It has been found that Li[Ni0.333Co0.333Mn0.293Al0.04]O1.95F0.05 showed an improved cathodic behavior and discharge capacity retention compared to the undoped samples in the voltage range of 3.0-4.3V The electrodes prepared from Lt[Ni0.333Co0.333Mn0.293Al0.04]O1.95F0.05 delivered an initial discharge capacity of 158 mAh(-1) g and an initial coulombic efficiency is 91.3%, and the capacity retention at the 20th cycle was 94.9%. Though the F-doped samples had lower initial capacities, they showed better cycle performances compared with F-free samples. Therefore, this is a promising material for a lithium-ion battery. (c) 2006 Elsevier B.V. All rights reserved.