Patent ID: 8343663

Claim:
A method of preparing a positive active material, comprising: heating a hydroxide compound that includes nickel and cobalt, or nickel, cobalt, and at least one metal selected from the group consisting of Al, Cr, Fe, Mg, Sr, V, and rare earth elements, or nickel, cobalt, and manganese, or nickel, cobalt, manganese, and at least one metal selected from the group consisting of Al, Cr, Fe, Mg, Sr, V, and rare earth elements to obtain an oxide material; mixing the oxide material with a lithium-containing compound; performing a first heat treatment to the resulting mixture; and performing a second heat treatment to the first heat-treated mixture to obtain a lithium/nickel-based compound, wherein primary particles of the positive active material have an average particle diameter ranging from 1 μm to 4 μm are agglomerated to form secondary particles of the lithium/nickel-based compound and, wherein the heat treatment of the hydroxide compound is performed at 700 to 1000° C.