Abstract: The present invention relates to the field of lithium-ion battery, and particularly to high-capacity cathode material, and high-energy density lithium-ion secondary battery prepared using the same. The cathode material comprises cathode active material, a binder and a conductive agent, in which the cathode active material is a compound material of lithium cobalt oxide-based active material A and nickel-based active material B pretreated before being mixed, and the mass ratio B/A of the lithium cobalt oxide-based active material A and nickel-based active material B is between 0.82 and 9. The present invention can produce a battery having both larger capacity and higher energy density, and address the problem of gas generation in the battery at high temperature.