A rheological phase method was employed successfully to synthesize LiNi_0.85Co_0.15O₂ cathode materials for lithium-ion batteries. LiNi_1－yCo_yO₂ (y＝0.10, 0.15, 0.20, 0.25) compounds were calcined for 6 h at 600～850 ℃ under flowing oxygen. And these samples were characterized by powder X-ray diffraction (XRD) and electrochemical tests. Lattice parameters from XRD patterns of LiNi_0.85Co_0.15O₂ calcined at 800 ℃ show that a＝0.2866 nm, c＝1.4193 nm and the lattice volume V＝0.1010 nm³. The first discharge capacity of LiNi_0.85Co_0.15O₂ synthesized at 800 ℃ for 6 h was 198.2 mAh/g, and the 20th discharge capacity was still above 174 mAh/g, at a 0.1 C rate between 3.0～4.3 V (vs. Li^＋/Li).

Key words: rheological phase method, lithium-ion battery, cathode material, LiNi_0.85Co_0.15O₂