Abstract: A positive electrode active material includes a lithium transition metal oxide in the form of a single particle; and a coating part which is formed on the surface of the lithium transition metal oxide and contains cobalt. The lithium transition metal oxide in the form of a single particle has interfaces divided into a strong boundary having collapse of a layered structure in a crystal particle and a weak boundary having no collapse of the layered structure. The coating part is formed only at the strong boundary among the interfaces. A method for producing the positive electrode active material is also provided.

Abstract: A positive electrode active material in a form of a single particle includes a lithium transition metal oxide in a form of a single particle, a coating portion containing cobalt which is formed on the lithium transition metal oxide in the form of a single particle, and LiCoO2 in a form of an island which is discontinuously formed on a surface. A ratio of an intensity of a peak ranging from 550 cm?1 to 620 cm?1 corresponding to an A1g vibration mode of LiCoO2 to an intensity of a peak ranging from 500 cm?1 to 600 cm?1 corresponding to an A1g vibration mode of LiNiO2 in a Raman spectrum of the surface is in a range of 0.1 to 1. Also provided is a method of preparing a positive electrode active material in a form of a single particle.

Abstract: Provided is a positive electrode active material which includes an inner region that is a region from the center of the positive electrode active material particle to R/2, and an outer region that is a region from R/2 to the surface of the positive electrode active material particle, wherein R is a distance from the center of the positive electrode active material particle to the surface thereof. The positive electrode active material further includes 25% to 80% of crystallites C with respect to a total number of crystallites in the outer region. The crystallites C have a high crystallite long-axis orientation degree of 0.5 to 1 and a low crystallite c-axis orientation degree less than 0.5. Thus, the positive electrode active material has high capacity characteristics and a small amount of gas generated.

Abstract: Provided is a positive electrode active material which includes an inner region that is a region from the center of the positive electrode active material particle to R/2; and an outer region that is a region from R/2 to the surface of the positive electrode active material particle, wherein R is a distance from the center of the positive electrode active material particle to the surface thereof. The positive electrode active material further includes 30% to 80% of crystallites A with respect to a total number of crystallites in the outer region of the positive electrode active material, the crystallites A having high crystallite long-axis orientation degree and crystallite c-axis orientation degree. Thus, the positive electrode active material can achieve excellent capacity characteristics and service life characteristics.

Abstract: A method of preparing a positive electrode active material which includes a first step of preparing a cake including a lithium transition metal oxide having a lithium borate compound formed on a surface thereof by mixing a positive electrode active material precursor having a specific composition, a lithium-containing raw material, and a boron-containing raw material and sintering the mixture, and a second step of grinding the cake and washing the ground cake to prepare a lithium transition metal oxide having the lithium borate compound removed therefrom. The method reduces the problems of breaking lithium transition metal oxide during the post processing steps by reduction in cake strength and change in the strength over time, thereby providing a positive electrode active material having improved quality.