Cathode material and preparation method thereof, composite cathode material, and battery

A cathode material, comprising:

• a plurality of composite secondary particles, each of the composite secondary particles comprising a plurality of primary cathode material particles, wherein the composite secondary particles meet Relation 1:
• 0.9≤0.1D/A+B*C≤20 (Relation 1)
• where A represents a particle size D50 of the primary cathode material particles, unit:
• μm;
• B represents a particle size D50 of the composite secondary particles, unit:
• μm;
• C represents a specific surface area of the composite secondary particles, unit:
• m2/g;
• and D represents a number of the primary cathode material particles in each of the composite secondary particles,
• wherein A is in the range of:
• 0.5≤A≤3.5, B is in the range of:
• 3≤B≤12, C is in the range of:
• 0.5≤C≤1.0, and D is in the range of:
• 1≤D≤50.