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

A preparation method of a positive electrode active material, the method comprising:

• preparing a first particle having a first average particle diameter;
• preparing a second particle having a second average particle diameter smaller than the first average particle diameter;
• and
• mixing the first particle and the second particle,
• wherein the preparing of the first particle comprises
• mixing a first iron phosphate precursor, a first lithium source, a first carbon source, and a first dopant source to form a first mixture,
• drying the first mixture through spray drying, and
• calcining the dried first mixture,
• the preparing of the second particle comprises
• mixing a second iron phosphate precursor, a second lithium source, a second carbon source, and a second dopant source to form a second mixture,
• performing wet grinding on the second mixture,
• drying the second mixture, and
• calcining the dried second mixture, and
• the first particle and the second particle are mixed such that an amount of the first particle is equal to or greater than an amount of the second particle.