POSITIVE ELECTRODE ACTIVE MATERIAL PRECURSOR, MANUFACTURING METHOD THEREOF, POSITIVE ELECTRODE ACTIVE MATERIAL, POSITIVE ELECTRODE, AND ELECTROCHEMICAL DEVICE

The present invention provides a positive electrode active material including at least one of a single particle composed of one nodule and a pseudo-single particle that is a composite of 30 or less nodules, wherein a degree of single crystal formation defined by Equation (A) is 2.7 or more. Degree of single crystal formation = ∑ i = 1 n 4 π 3 × R i 3 n [0002] In Equation (A), R is a radius of an i grain which is measured when an electrode prepared by using the positive electrode active material is subjected to an ion-milling treatment and a cross-section of the electrode is then analyzed by electron backscatter diffraction (EBSD), wherein R is a value measured in µm units, but a value substituted into Equation (A) is a unitless number that does not include units, and n is the total number of grains measured by the electron backscatter diffraction (EBSD) analysis.