Positive active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including the same

A method of preparing a positive active material for a rechargeable lithium battery, the method comprising:

• mixing at least one core material selected from a nickel-based composite oxide represented by Chemical Formula 1 or a lithium manganese oxide represented by Chemical Formula 2 and a solution comprising a salt comprising at least one tetravalent element selected from Zr or Ti to form a mixture;
• and
• heat-treating the mixture to coat a surface of the core material with a lithium metal oxide represented by Chemical Formula 3:
• LiNixCoyMn1-x-yO2 Chemical Formula 1
• wherein 0.1≦x≦0.8, and 0.1≦y≦0.8,
• LiaMnbOc Chemical Formula 2
• wherein 1≦a≦2, 1≦b≦2, and 2≦c≦4, and
• Li2MO3 Chemical Formula 3
• wherein M is at least one tetravalent element selected from Zr or Ti.

A method of preparing a positive active material for a rechargeable lithium battery, the method comprising:

• mixing a salt comprising at least one tetravalent element selected from Zr or Ti and a first solvent to form a salt solution;
• mixing a chelating agent and a second solvent to form a chelating agent solution;
• mixing the salt solution and the chelating agent solution to form a first mixed solution;
• mixing the first mixed solution and a homogenizer to form a second mixed solution;
• mixing at least one core material selected from a nickel-based composite oxide represented by Chemical Formula 1 or a lithium manganese oxide represented by Chemical Formula 2 and the second mixed solution to form a mixture;
• and
• heat-treating the mixture to coat a surface of the core material with a lithium metal oxide represented by Chemical Formula 3:
• LiNixCoyMn1-x-yO2 Chemical Formula 1
• wherein 0.1≦x≦0.8, and 0.1≦y≦0.8,
• LiaMnbOc Chemical Formula 2
• wherein 1≦a≦2, 1≦b≦2, and 2≦c≦4, and
• Li2MO3 Chemical Formula 3
• wherein M is at least one tetravalent element selected from Zr or Ti.

A rechargeable lithium battery comprising

• a positive electrode comprising the positive active material according to claim
• a negative electrode;
• and
• an electrolyte.