Positive active material for rechargeable lithium batteries and method for preparing same

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

• coating a lithiated compound with an organic solution or aqueous solution including a coating-element source, the lithiated compound comprising a secondary particle with an average particle size larger than or equal to 1 μm and smaller than 10 μm in diameter, the secondary particle being formed of an agglomeration of small primary particles having an average particle size of 1 to 3 μm in diameter;
• and
• heat-treating the coated lithiated compound.

A positive active material for a rechargeable lithium battery comprising:

• a core comprising a lithium-cobalt chalcogenide compound, the lithium-cobalt chalcogenide compound comprising a secondary particle having an average size larger than or equal to 1 μm and smaller than 10 μm in diameter, the secondary particle being formed of an agglomeration of small primary particles of an average size of 1 to 3 μm in diameter;
• and
• a surface-treatment layer formed on the core, the surface-treatment layer including one compound selected from the group consisting of Al2O3, Al(OH)3, AlO(OH), and mixtures thereof.

A positive active material for a rechargeable lithium battery comprising:

• a core comprising a lithium-manganese or lithium-cobalt chalcogenide compound, the lithium-manganese or lithium-cobalt chalcogenide compound comprising a secondary particle having an average size larger than or equal to 1 μm and smaller than 10 μm in diameter, the secondary particle being formed of an agglomeration of small primary particles of an average size of 1 to 3 μm in diameter;
• and
• a surface-treatment layer on the core, the surface-treatment layer comprising a B-included oxide or HB(OH)2 on the core.