MATÉRIAU ACTIF DE CATHODE POUR BATTERIE RECHARGEABLE, SON PROCÉDÉ DE PRÉPARATION ET BATTERIE RECHARGEABLE AU LITHIUM COMPRENANT CELUI-CI

摘要

The present invention relates to a positive electrode active material for a secondary battery, which includes a core part and a shell part formed around the core part. Here, the core part and the shell part include a lithium composite transition metal oxide including Ni and Co, and at least one or more selected from the group consisting of Mn and Al, and a ratio of the diameter of the core part to the total diameter of a particle of the positive electrode active material is 0.5 to 0.85, and the shell part has a concentration gradient such that a Ni concentration at the start point of the shell part near the core part is 30 mol% or higher than that at the end point of the shell part near the particle surface.