The present invention relates to positive electrode active material slurry of which degree of non-crystallinity is controlled by including a rubber-based binder in a specific ratio, a positive electrode including a positive electrode active material layer formed therefrom, and a lithium secondary battery including the positive electrode. The positive electrode active material layer formed from the positive electrode active material slurry has enhanced flexibility and rolling property, and internal short circuits, high voltage defects and capacity decline of the lithium secondary battery using the positive electrode including the same are capable of being suppressed.