Lithium-containing transition metal composite oxide, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, lithium secondary battery, and method for manufacturing lithium-containing transition metal composite oxide
This lithium-containing transition metal composite oxide includes secondary particles that are aggregates of primary particles into or from which lithium ions are dopable or dedopable, and satisfies the following conditions: (1) the lithium-containing transition metal composite oxide is represented by Formula (I), Li[Li x (Ni (1-y-z-w) Co y Mn z M w ) 1-x ]O 2 (I) (2) from X-ray photoelectron spectroscopy, a specific γ is calculated for each of the surface of the secondary particle and the inside of the secondary particle, and when the γ value of the surface of the secondary particle is referred to as γ1 and the γ value of the inside of the secondary particle is referred to as γ2, γ1 and γ2 satisfy the condition of Formula (II). 0.3≤γ1/γ2≤1.0 (II)
1. A lithium-containing transition metal composite oxide, comprising:
secondary particles that are aggregates of primary particles into or from which lithium ions are dopable or dedopable,
wherein a 50% cumulative volume particle size D 50 of the lithium-containing transition metal composite oxide is 5 μm or more and 20 μm or less,
wherein the lithium-containing transition metal composite oxide satisfies the following conditions,
(1) the lithium-containing transition metal composite oxide is represented by Formula (I),
Li[Li x (Ni (1-y-z-w) Co y Mn z M w ) 1-x ]O 2 (I)
(in Formula (I), 0≤x≤0.1, 0<y≤0.5, 0≤z≤0.8, 0≤w≤0.1, and y+z+w<1 are satisfied, and M represents one or more metals 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), and
(2) when an area value of a peak appearing at 53.8 eV in a lithium 1 s spectrum is referred to as a and an area value of a peak appearing at 529.0 eV in an oxygen 1 s spectrum is referred to as β when X-ray photoelectron spectroscopy is performed, and a ratio between α and β is referred to as γ (α/β=γ),
γ is calculated for each of a surface of the secondary particle and an inside of the secondary particle, and when a γ value of the surface of the secondary particle is referred to as γ1 and a γ value of the inside of the secondary particle is referred to as γ2, γ1 and γ2 satisfy a condition of Formula (II)
0.3≤γ1/γ2<1.0 (II)
wherein the lithium-containing transition metal composite oxide is manufactured by a method comprising:
a mixing step of mixing a lithium compound and a metal composite compound containing at least nickel to obtain a mixture;
a baking step of baking the mixture to obtain a baked product; and
a washing step of washing the baked product,
wherein, in the mixing step, mixing is performed so that a molar ratio (Li/Me, a molar ratio of lithium to a total amount of metal elements excluding lithium) between lithium contained in the lithium compound and metal elements in the metal composite compound containing at least nickel exceeds 1, and
in the washing step, a temperature of a washing solution used for washing is set to −20° C. or higher and 40° C. or lower, and washing is performed in an amount of the washing solution used for washing such that a concentration of lithium carbonate in the washing solution in a case where it is assumed that a total amount of residual lithium carbonate contained in the baked product before washing is dissolved in the washing solution is 1/10 or more and 3 or less times a solubility of lithium carbonate in the washing solution at the temperature of the washing solution during the washing step.
2. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein an element ratio R (Li (Atom %)/O (Atom %)) calculated from the peak appearing at 53.8 eV in the lithium 1 s spectrum and the peak appearing at 529.0 eV in the oxygen 1 s spectrum when the X-ray photoelectron spectroscopy is performed is 0.4≤R≤0.8 in the inside of the secondary particle.
3. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein a BET specific surface area (m 2 /g) is 0.1 or more and 3.0 or less.
4. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein a crystallite size L 003 at a peak within a range of 2θ=18.7±1° in a powder X-ray diffraction measurement using CuKα radiation is 400 Å or more and 1300 Å or less.
5. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein a difference between a maximum particle size D max and a minimum particle size D min (μm) is D 50 ×⅔ or more.
6. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein, in Formula (I), 0<x≤0.1 is satisfied.
7. A positive electrode active material for a lithium secondary battery, comprising:
the lithium-containing transition metal composite oxide according to claim 1 .
8. A positive electrode for a lithium secondary battery, comprising:
the positive electrode active material for a lithium secondary battery according to claim 7 .
9. A lithium secondary battery, comprising:
the positive electrode for a lithium secondary battery according to claim 8 .
10. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein in the washing step, a temperature of a slurry containing the baked product and a washing solution used for washing is maintained at −20° C. or higher and lower than 10° C.
11. The lithium-containing transition metal composite oxide according to claim 1 ,
wherein, in Formula (I), 0.01≤z≤0.4 is satisfied.