Cathode active material for lithium secondary battery and lithium secondary battery including same

A cathode active material for a lithium secondary battery, comprising:

• a secondary particle in which a plurality of primary particles are agglomerated,
• the secondary particle comprising a core and a surface portion, and having a predetermined arrangement structure in which (003) surfaces of primary particles of the plurality of primary particles are aligned to be in a vertical direction with respect to respective tangent lines at points (P) at which the (003) surfaces of the primary particles meet a surface of the secondary particle;
• and
• wherein the vertical direction in which the (003) surfaces of the primary particles are aligned is 90°±20° with respect to the respective tangent lines;
• wherein a pore volume fraction of micropores of less than or equal to 10 nm of the secondary particle is greater than or equal to 10% of a total pore volume, and the micropores of less than or equal to 10 nm are at the surface portion of the secondary particle;
• and
• wherein the secondary particle has an average pore size that decreases sequentially from an average pore size of the core to an average pore size of the surface portion.