Method for Manufacturing Mixture of Positive Electrode Active Material Particles of Nickel-Rich Lithium Composite Transition Metal Oxide

A method for manufacturing a mixture of positive electrode active material particles of nickel-rich lithium composite transition metal oxide is disclosed herein. In some embodiments, the method includes washing first positive electrode active material particles having first average particle size and consisting of a first lithium composite transition metal oxide having a nickel content of 80 mol % or more based on a total amount of transition metals in the oxide, washing second positive electrode active material particles having a second average particle size and consisting of a second lithium composite transition metal oxide having a nickel content of 80 mol % or more based on a total amount of transition metals in the oxide, wherein the first and second average particle sizes are different, mixing the washed first and second positive electrode active material particles to manufacture a mixture of positive electrode active material particles; and filtering and drying the mixture.