POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM-ION BATTERY, POSITIVE ELECTRODE FOR LITHIUM-ION BATTERY, AND LITHIUM-ION BATTERY

The present invention provides a positive electrode active material for lithium ion batteries having excellent rate performance. [0002] The positive electrode active material for lithium ion batteries having a layered structure is represented by composition formula: Li(NiM)O, wherein M is Mn and Co, x is 0.9 to 1.2, y is 0.6 to 0.9, z is 1.8 to 2.4. D2/D1 is 1.065 or less, D1 being defined as the density of the positive electrode active material when powder of the positive electrode active material is pressed under the pressure of 100MPa, and D2 being defined as the density of the positive electrode active material when powder of the positive electrode active material is pressed under the pressure of 300MPa.