Negative active material, method of preparing same, and rechargeable lithium battering including same

A negative active material for a rechargeable lithium battery including lithium titanium oxide is provided. The lithium titanium oxide has a full width at half maximum (FWIIM) of 2¸ ranging from about 0.08054° to about 0.10067° at a (111) plane (main peak, 2¸ = 18.330°) as measured by XRD using a Cu Ka ray.