Lithium secondary battery

A lithium secondary battery, comprising:

• a cathode;
• an anode;
• and
• a non-aqueous electrolyte solution,
• wherein the cathode includes a cathode active material including a lithium-metal oxide which is doped with a dopant element,
• wherein the lithium-metal oxide is represented by Formula 1 below,
• LixM1aM2bM3cOy Formula 1
• wherein M1, M2 and M3 are selected from a group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B,
• 0<x≤1.1, 2≤y≤2.02, 0<a<1, 0<b<1, 0<c<1, and 0<a+b+c≤1,
• wherein the cathode active material comprises
• a central portion within 0.1 μm to 0.2 μm radius from a center of the cathode active material;
• a surface portion within 0.1 μm but not less than 0.05 μm from an outmost portion of the cathode active material;
• and
• an intermediate region between the central portion and the surface portion, the intermediate region comprising a concentration gradient region wherein M1 and M3 have a concentration gradient in a direction from the central portion to the surface portion, and a non-concentration gradient region wherein M1 and M3 do not have a concentration gradient in a direction from the central portion to the surface portion;
• and
• wherein M2 has a constant concentration throughout the cathode active material from the central portion to the surface portion.