Positive electrode material for lithium secondary battery, and positive electrode and lithium secondary battery including same

A positive electrode material having a bimodal particle size distribution, comprising large-diameter particles and small-diameter particles having different average particle diameters (D50),

• wherein the large-diameter particles are a lithium composite transition metal oxide having a nickel content of 80 atm % or greater in all transition metals, and
• the small-diameter particles are a lithium composite transition metal oxide including nickel, cobalt, and aluminum, having a nickel content of 80 atm % to 85 atm % in all transition metals, and having an atomic ratio of the cobalt to the aluminum (Co/Al) of 1.5 to 5,
• wherein the small-diameter particles comprise a lithium composite transition metal oxide represented by Formula 1 below, and
• wherein the large-diameter particles comprise a lithium composite transition metal oxide represented by Formula 3 below:
• Lix[NiyCozAlwM1v]O2 [Formula 1]
• wherein,
• M1 is one or more selected from the group consisting of Mn, W, Cu, Fe, Ba, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and
• 0.9≤x≤1.5, 0.8≤y≤0.85, 0<z≤0.1, 0<w≤0.1, 1.5≤z/w≤5, and 0≤v<0.2,
• Lia[NibCocM2dM3e]O2 [Formula 3]
• wherein,
• M2 is Ald1Mnd2,
• M3 is one or more selected from the group consisting of W, Cu, Fe, Ba, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and
• 0.9≤a≤1.5, 0.8≤b<1, 0<c≤0.15, 0<d<0.2, 0<d1≤0.1, 0<d2<0.2, and 0≤e<0.2.