Production method of lithium-containing composite oxide and lithium-containing composite oxide

A lithium-containing composite oxide represented by Formula 5-B,

• wherein a peak intensity ratio (I003/I104) of an integral value (I003) of a diffraction peak of the (003) plane and an integral value (I104) of a diffraction peak of the (104) plane in an X-ray diffraction pattern is from 1.18 to 1.35, and a crystallite size of the (110) plane in the X-ray diffraction pattern is less than 30 nm;
• and
• wherein Formula 5-B is:
• Liα2Nix2Mny2Coz2Mea2Ob2 . . . ,
• wherein Me represents at least one type of element selected from the group consisting of Mg, Ca, Al, Ti, V, Cr, Nb, Mo, W, and Zr, and wherein α2, x2, y2, z2, a2, and b2 satisfy the relations of 1.02≤α2≤1.2, 0.3<x2≤0.6, 0.2≤y2≤0.4, 0.15≤z2≤0.35, 0≤a2≤0.1, x2+y2+z2+a2=1, and 1.9≤b2≤2.1 respectively.