The invention provides a 
cathode material, which comprises a base material and an aluminum 
oxide layer, wherein the base material is prepared from a compound as shown in a formula I and a compound as shown in a formula II; the compound as shown in the formula I has a secondary particle morphology which is formed by agglomeration of a plurality of 
single crystal grains; the compound as shown in the formula II has a single-
crystal structure; and the aluminum 
oxide layer coats the surface of the base material. The base material in the 
cathode material provided by the invention is prepared from the compound with the particle morphology and the compound with the single-
crystal structure; due to the two morphologies of compounds, the 
cathode material has relatively good capacity characteristic; and the processability can also be improved. The aluminum 
oxide layer coats the surface of the base material in the 
cathode material provided by the invention; 
corrosion to the 
surface layer of the 
cathode material caused by 
moisture and HF in a battery can be avoided or reduced by 
coating of the aluminum oxide layer; and due to the 
cathode material with an aluminum oxide layer 
coating layer, the prepared 
lithium-
ion battery has relatively high working 
voltage and 
heat stability. The invention further provides a preparation method of the cathode material and the 
lithium-
ion battery.