Lithium metal composite oxide powder, positive electrode active substance for lithium secondary battery, positive electrode for lithium secondary battery, and lithium secondary battery
A lithium metal composite oxide powder, which comprises primary particles and secondary particles that are aggregates of the primary particles, and has an α-NaFeO 2 type crystal structure, wherein a half width (A) of a diffraction peak in a range of 2θ=18.7±1° in a powder X-ray diffraction measurement for the lithium metal composite oxide powder using CuKα ray is 0.135° or more and 0.165° or less, and a c-axis lattice constant of the α-NaFeO 2 type crystal structure is 14.178 Å or more and 14.235 Å or less.
1. A lithium metal composite oxide powder, which comprises primary particles and secondary particles that are aggregates of the primary particles, and has an α-NaFeO 2 type crystal structure,
wherein a half width (A) of a diffraction peak in a range of 2θ=18.7±1° in a powder X-ray diffraction measurement for the lithium metal composite oxide powder using a CuKα ray is 0.135° or more and 0.165° or less,
wherein a c-axis lattice constant of the α-NaFeO 2 type crystal structure is 14.178 Å or more and 14.235 Å or less,
wherein the powder X-ray diffraction measurement is performed using the CuKα ray under a condition of a diffraction angle of 2θ=10° to 90°, a sampling width of 0.02°, and a scan speed of 4°/min, and
wherein the lithium metal composite oxide powder satisfies composition formula (I)
Li[Li x (Ni (1−y−z−w) CO y Mn z M w ) 1−x ]O 2 (I),
wherein −0.1≤x≤0.2, 0≤y≤0.4, 0≤z≤0.4, 0≤w≤0.1, y+z+w≤0.3, and M is 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.
2. The lithium metal composite oxide powder according to claim 1 , wherein a half width (B) of a diffraction peak in a range of 2θ=44.4±1° in the powder X-ray diffraction measurement using CuKα ray is 0.170° or more and 0.240° or less.
3. The lithium metal composite oxide powder according to claim 1 , wherein in the composition formula (I), 0<x≤0.2.
4. The lithium metal composite oxide powder according to claim 1 , further comprising single particles.
5. The lithium metal composite oxide powder according to claim 1 , wherein an amount of lithium hydroxide is 0.3% by mass or less with respect to a total mass of the lithium metal composite oxide powder, in terms of a value converted from a neutralization titration result for the lithium metal composite oxide powder.
6. The lithium metal composite oxide powder according to claim 1 , which has an average particle diameter (D 50 ) of 100 nm or more and 10 μm or less as determined by a particle size distribution measurement.
7. The lithium metal composite oxide powder according to claim 1 , which has a minimum particle diameter (D min ) of 50 nm or more and 2 μm or less as determined by a particle size distribution measurement.
8. A positive electrode active material for a lithium secondary battery, which comprises the lithium metal composite oxide powder of claim 1 .
9. A positive electrode for a lithium secondary battery, which comprises the positive electrode active material of claim 8 .
10. A lithium secondary battery, which comprises the positive electrode of claim 9 .
11. The lithium metal composite oxide powder according to claim 1 ,
wherein the c-axis lattice constant of the α-NaFeO 2 type crystal structure is 14.178 Å or more and 14.193 Å or less.