Abstract: A method for preparing a positive electrode active material precursor includes preparing a metal aqueous solution including a nickel raw material, a cobalt raw material, and a manganese raw material (step 1); adding the metal aqueous solution, an ammonium cation complex forming agent, and a basic aqueous solution into a reactor, co-precipitating the mixture at pH 11 to less than pH 12 to form nuclei of first positive electrode active material precursor particles and growing the nuclei (step 2); adjusting input amount of the basic aqueous solution to increase the pH in the reactor to a range of 0.8 to 1.5 compared to that of step 2; and adjusting input amount of the basic aqueous solution to change the pH in the reactor to pH 11 to less than pH 12 (step 4). A positive electrode active material precursor prepared by the above preparation method has an improved packing density.

Abstract: A positive electrode active material precursor having a uniform particle size distribution and represented by Formula 1, wherein a percentage of fine powder with an average particle diameter (D50) of 1 ?m or less is generated when the positive electrode active material precursor is rolled at 2.5 kgf/cm2 is less than 1%, and an aspect ratio is 0.93 or more, and a method of preparing the positive electrode active material precursor [NixCoyM1zM2w](OH)2 ??[Formula 1] in Formula 1, 0.5?x<1, 0<y?0.5, 0<z?0.5, and 0?w?0.1, M1 includes at least one selected from the group consisting of Mn and Al, and M2 includes at least one selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y. A method of preparing the positive electrode active material precursor is also provided.

Abstract: In a method of classifying directional defects on an object straight lines are drawn from any defect among all defects on the object toward adjacent defects. At least three defects that are positioned within an allowable angle from the straight lines are classified as directional defects. Thus, only the directional defects among all the defects on the semiconductor substrate may be accurately classified after performing a chemical mechanical polishing (CMP) process, so that the CMP process may be effectively managed.