POSITIVE ELECTRODE ACTIVE MATERIAL FOR SECONDARY BATTERIES, AND SECONDARY BATTERY

A positive electrode active material for secondary batteries which is one example of the embodiment comprises a first lithium-nickel composite oxide having a volume-based D50 value of 8 μ82 m to 30 μm inclusive and a second lithium-nickel composite oxide having a volume-based D50 value of 6 μm or less. At least one component selected from Ca and Sr is present on the surfaces of primary particles constituting the second lithium-nickel composite oxide. The total content of Ca and Sr in the second lithium-nickel composite oxide is larger than that in the first lithium-nickel composite oxide.