Cathode active material for lithium secondary battery and method of manufacturing the same

A method of preparing a cathode active material for a lithium secondary battery, comprising:

• preparing a preliminary lithium metal oxide particle;
• cleaning the preliminary lithium metal oxide particle using a washing solution that includes a thiosulfate anion (S2O32−) salt;
• and
• drying or annealing the washed preliminary lithium metal oxide particle to obtain a lithium metal oxide particle including a thiosulfate anion formed on at least portion of a surface thereof;
• wherein a content of the thiosulfate anion of the lithium metal oxide particle including a thiosulfate anion measured by an ion chromatography analysis is in a range from 100 ppb to 8,000 ppb.