Abstract: A synthetic route for the preparation of Li［Ni_1/2Mn_1/2］O₂，a cathode material of lithium ion battery，by co- precipitation method with carbonate as precursor was introduced.X-ray diffraction（XRD） was used to analyze the sample and results indicated the sample had a layer structure which was similar with LiCoO₂.The particle size and morphology were characterized by scan electron microscopy（SEM），and the SEM results indicated that the sample had a regular spherical shape， and the particle size was at 5~10 μm.The result of electrochemical test showed that initial discharge specific capacity of the Li［Ni_1/2Mn_1/2］O₂ was above 170 mA·h/g，and the specific capacity retention could keep more than 98% after 20 times charge-discharge cycles.

Key words: lithium ion battery, cathode material, Li［Ni_1/2Mn_1/2］O₂