Lithium metal composite oxide, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, and lithium secondary battery

A lithium metal composite oxide comprising:

• a secondary particle which is an aggregate of primary particles;
• and
• a single particle which exists independently of the secondary particle,
• wherein the lithium metal composite oxide has a layered rock-salt structure, is represented by Composition Formula (I) below, satisfies (1) and (2) below,
• L
• ⁢
• i
• x
• ⁢
• Ni
• 1
• ⁢
• ‐
• ⁢
• y
• ⁢
• ‐
• ⁢
• z
• ⁢
• ‐
• ⁢
• w
• ⁢
• Co
• y
• ⁢
• Mn
• z
• ⁢
• X
• ⁢
• 1
• w
• ⁢
• O
• 2
• (
• I
• )
• (here, Composition Formula (I) satisfies 0.9≤x≤1.2, 0≤y≤0.4, 0≤z≤0.4, 0≤w≤0.1, and y+z+w≤1, and X1 represents one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, In, and Sn),
• 1.2
• ≤
• L
• A
• /
• L
• B
• <
• 1.6
• (
• 1
• )
• (LA is a crystallite diameter obtained from a diffraction peak 1 within a range of 2θ=18.8±1° and LB is a crystallite diameter obtained from a diffraction peak 2 within a range of 2θ=38.3±1° in a diffraction peak obtained from powder X-ray diffraction using CuKα rays), and
• (2):
• a Me occupancy at a lithium site in the layered rock-salt structure is 2.5% or less, as determined by analyzing the diffraction peaks by the Rietveld analysis method, and the Me is Ni, Co, Mn, or X1.