Composite precursor of cathode active material, cathode active material, cathode and lithium battery containing the cathode active material, and method of preparing composite precursor

A composite cathode active material precursor having spherical primary particles and secondary particles, comprising:

• a composite phase comprising a cobalt hydroxide and a cobalt oxyhydroxide,
• wherein an XRD spectrum of the precursor has a first doublet peak corresponding to the cobalt oxyhydroxide at a diffraction angle (2θ) of 19.5°±1.0° and a second peak corresponding to the cobalt hydroxide at a diffraction angle (2θ) of 38.5°±0.5°,
• wherein an average particle diameter of the spherical primary particles of the composite cathode active material precursor is about 1 μm or less,
• wherein the tap density of the composite cathode active material precursor is greater than 2.0 g/cm3, and
• wherein the spherical primary particles have a sphericity, calculated using circularities of two dimensional projections of the spherical primary particles, of about 0.7 or higher.