The method for producing a positive electrode active material for a rechargeable lithium battery

PROBLEM TO BE SOLVED: To provide a positive active material for a lithium secondary battery, in which the particle size of primary particles are large and uniform, most primary particles are surrounded only with spaces, and accordingly, cycle characteristics are high when used as the positive active material; and to provide the manufacturing method of the positive active material. SOLUTION: The positive active material for the secondary battery is represented by compositional formula: Li x Ni 1-y-z Co y M z O 2 (M is at least one kind of element selected from Mn, Al, Zr, Si, Sr and Mg; x, y, and z are a number satisfying 0.95≤x≤1.10, 0.1≤y≤0.4, and 0≤z≤0.1), and in the positive active material, a median diameter measured with a laser diffraction particle size distribution measuring device is in a range of 2 to 20 μm, the average major axis of primary particle diameter by SEM observation of particle cross section treated with a cross section polisher is in a range of 1 to 10 μm, (the median diameter)/(the average major axis of primary particle diameters of the particle cross sections) is in a rang of 1.0 to 3.0, 5% diameter of volume basis cumulative distribution is median diameter/3 or more, 95% diameter is 3 times or less the median diameter. The manufacturing method of the positive active material of the lithium secondary battery is provided. COPYRIGHT: (C)2010,JPO&INPIT