LITHIUM METAL COMPOSITE OXIDE, POSITIVE ELECTRODE FOR LITHIUM SECONDARY BATTERY, AND LITHIUM SECONDARY BATTERY
A lithium metal composite oxide having a layered structure, containing Li, Ni, and an element X, in which the element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P, Ni/(Ni+X), which is a ratio of the number of moles of Ni to the total number of moles of Ni and the element X, is 0.7 or more, and in a powder X-ray diffraction measurement of the lithium metal composite oxide using CuKα rays, a diffraction peak is present within a range of a diffraction angle 2θ=18.7±1°, and a relative standard deviation of a volume-based crystallite size distribution calculated from the diffraction peak within the range of 2θ=18.7±1° is 0.20 or more and 0.55 or less.
1 . A lithium metal composite oxide having a layered structure, comprising:
Li;
Ni; and
an element X,
wherein the element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P,
Ni/(Ni+X), which is a ratio of the number of moles of Ni to the total number of moles of Ni and the element X, is 0.7 or more, and
in a powder X-ray diffraction measurement of the lithium metal composite oxide using CuKα rays, a diffraction peak is present within a range of a diffraction angle 2θ=18.7±1°, and a relative standard deviation of a volume-based crystallite size distribution calculated from the diffraction peak within the range of 2θ=18.7±1° is 0.20 or more and 0.55 or less.
2 . The lithium metal composite oxide according to claim 1 ,
wherein, with regard to a crystallite size distribution function curve obtained from the diffraction peak, in which a horizontal axis is a volume-based crystallite size and a vertical axis is a probability density function of a crystallite with respect to the crystallite size, in a region surrounded by the crystallite size distribution function curve and the horizontal axis, a proportion of an area of a portion in the region in which the crystallite size is 1,000 Å or less to a total area of the region is 0.5% or more and 50% or less.
3 . The lithium metal composite oxide according to claim 1 , wherein the lithium metal composite oxide is represented by a composition formula (I),
Li[Li x (Ni (1-y-z) Co y M z ) 1-x ]O 2 (I)
and in the formula (I), M represents at least one element selected from the group consisting of Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P, and −0.1≤x≤0.2, 0<y≤0.2, 0<z≤0.2, and y+z≤0.3 are satisfied.
4 . The lithium metal composite oxide according to claim 1 ,
wherein a 50% cumulative volume particle size D 50 which is obtained from a volume-based cumulative particle size distribution curve measured by a laser diffraction scattering method is 5 μm or more and 30 μm or less.
5 . The lithium metal composite oxide according to claim 4 ,
wherein a ratio of a 90% cumulative volume particle size D 90 to a 10% cumulative volume particle size D 10 , which are obtained from the cumulative particle size distribution curve, is 1.5 or more and 4 or less.
6 . The lithium metal composite oxide according to claim 1 ,
wherein a tap density is 1.8 g/cc or more and 3.2 g/cc or less.
7 . A positive electrode for a lithium secondary battery, comprising:
a positive electrode active material containing the lithium metal composite oxide according to claim 1 .
8 . A lithium secondary battery comprising:
the positive electrode for the lithium secondary battery according to claim 7 .
9 . The lithium metal composite oxide according to claim 2 ,
wherein the lithium metal composite oxide is represented by a composition formula (I),
Li[Li x (Ni (1-y-z) Co y M z ) 1-x ]O 2 (I)
and in the formula (I), M represents at least one element selected from the group consisting of Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, B, Si, S, and P, and −0.1≤x≤0.2, 0<y≤0.2, 0<z≤0.2, and y+z≤0.3 are satisfied.
10 . The lithium metal composite oxide according to claim 2 ,
wherein a 50% cumulative volume particle size D 50 which is obtained from a volume-based cumulative particle size distribution curve measured by a laser diffraction scattering method is 5 μm or more and 30 μm or less.
11 . The lithium metal composite oxide according to claim 11 ,
wherein a ratio of a 90% cumulative volume particle size D90 to a 10% cumulative volume particle size D10, which are obtained from the cumulative particle size distribution curve, is 1.5 or more and 4 or less.
12 . The lithium metal composite oxide according to claim 2 ,
wherein a tap density is 1.8 g/cc or more and 3.2 g/cc or less.
13 . A positive electrode for a lithium secondary battery, comprising:
a positive electrode active material containing the lithium metal composite oxide according to claim 2 .
14 . A lithium secondary battery comprising:
the positive electrode for the lithium secondary battery according to claim 13 .