Abstract: A positive electrode active material including a first lithium composite oxide particle including a secondary particle formed by aggregation of one or more primary particles, and a coating oxide occupying at least a part of at least one of surfaces of the secondary particle, grain boundaries between the primary particles, or surfaces of the primary particles, the positive electrode active material satisfying an equation of 1.3?a/b?3.0, wherein a represents a max peak intensity at 2theta=44.75° to 44.80° and b represents a max peak intensity at 2theta=45.3° to 45.6° in X-ray diffraction (XRD) analysis using Cu K? radiation.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery using the same, and more particularly, to a bimodal-type positive electrode active material including a first lithium composite oxide as a small particle and a second lithium composite oxide as a large particle, which improves the transport ability of lithium ions by controlling the morphology or crystal structure of the small particle included in the positive electrode active material, and further alleviates or prevents the early deterioration or shortened lifetime of the bimodal-type positive electrode active material, caused by the small particle, by increasing the particle stability of the small particle, and a lithium secondary battery using the same.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a bimodal-type positive electrode active material including a first lithium composite oxide as a small particle and a second lithium composite oxide as a large particle, wherein the positive electrode active material may uniformly improve the particle stability of the small particle and the large particle by controlling a slope of a concentration gradient in which cobalt in the small particle and the large particle decreases from a surface portion toward a central portion, a positive electrode including the positive electrode active material, and a lithium secondary battery using the positive electrode.

Abstract: The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including a lithium composite oxide containing at least nickel and cobalt, wherein since the cobalt in the lithium composite oxide has a concentration gradient having at least different slopes from a surface portion toward a central portion, it is possible to improve the stability of particles not only in a surface portion of the lithium composite oxide but also in a central portion thereof, a positive electrode including the positive electrode active material, and a lithium secondary battery using the negative electrode.

Abstract: The present invention relates to a positive electrode active material, in which primary particles included in a secondary particle exhibit an aspect ratio gradient which gradually increases from the center of the secondary particle to the surface thereof, and a lithium secondary battery which uses a positive electrode containing the positive electrode active material.