LITHIUM METAL COMPOSITE OXIDE POWDER AND POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY
This lithium metal composite oxide powder has a layered crystal structure and includes at least Li, Ni, an element X, and an element M, in which the element X is one or more elements selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, and V, the element M is one or more elements selected from the group consisting of B, Si, S, and P, a content of the element M to a total amount of Ni and the element X in the lithium metal composite oxide powder is 0.01 mol % or more and 5 mol % or less, a content (Ni/(Ni+X)) of Ni to the total amount of Ni and the element X in the lithium metal composite oxide powder is 0.4 or more in terms of a mole ratio, and (1), (2), and (3) are satisfied.
1 . A lithium metal composite oxide powder having a layered crystal structure, the powder comprising:
at least Li, Ni, an element X, and an element M,
wherein the element X is one or more elements selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, and V,
the element M is one or more elements selected from the group consisting of B, Si, S, and P,
a ratio of a content of the element M to a total amount of Ni and the element X in the lithium metal composite oxide powder is 0.01 mol % or more and 5 mol % or less,
a ratio of a content of Ni to the total amount of Ni and the element X, which is indicated by Ni/(Ni+X), in the lithium metal composite oxide powder is 0.4 or more in terms of a mole ratio, and
the following (1), (2), and (3) are satisfied,
(1) a mole ratio between element concentrations of Li and the element M that is indicated by Li/element M continuously increases from a particle surface to a particle center of the lithium metal composite oxide powder,
(2) a mole ratio between element concentrations of O and the element M that is indicated by O/element M continuously increases from the particle surface to the particle center of the lithium metal composite oxide powder, and
(3) a mole ratio between the element concentrations of the element M and O that is indicated by element M/O inside the particle of the lithium metal composite oxide powder is 0.05 or less.
2 . The lithium metal composite oxide powder according to claim 1 that is represented by the following composition formula (A),
Li[Li n1 (Ni (1−z−w) X z M w ) 1−n1 ]O 2 (A)
(here, X is one or more elements selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga, and V, M is one or more elements selected from the group consisting of B, Si, S, and P, and 0≤n1≤0.2, 0<z≤0.6, and 0<w≤0.1 are satisfied).
3 . The lithium metal composite oxide powder according to claim 1 ,
wherein a BET specific surface area is 2 m 2 /g or less.
4 . The lithium metal composite oxide powder according to claim 1 ,
wherein an average primary particle diameter is 0.3 μm or more and 8 μm or less.
5 . The lithium metal composite oxide powder according to claim 1 ,
wherein, in a 10% cumulative diameter (D 10 ), a 50% cumulative diameter (D 50 ), and a 90% cumulative diameter (D 90 ), all of which are obtained from particle size distribution measurement values, the 50% cumulative diameter (D 50 ) is 2 μm or more and 10 μm or less, and furthermore, a relationship of the following formula (B) is satisfied,
0.3≤( D 90 −D 10 )/ D 50 ≤3 (B).
6 . The lithium metal composite oxide powder according to claim 1 ,
wherein a value obtained by dividing a moisture content (mass %) by a BET specific surface area (m 2 /g) that is indicated by moisture content (mass %)/BET specific surface area (m 2 /g) is 0.005 or more and 0.7 or less.
7 . The lithium metal composite oxide powder according to claim 1 ,
wherein a maximum concentration gradient R Li/M in a range where the mole ratio between the element concentrations of Li and the element M that is indicated by Li/element M continuously increases from the particle surface to the particle center of the lithium metal composite oxide powder is small compared with a maximum concentration gradient R O/M in a range where the mole ratio between the element concentrations of O and the element M that is indicated by O/element M continuously increases from the particle surface to the particle center of the lithium metal composite oxide powder (R O/M >R Li/M ).
8 . A positive electrode active material for a lithium secondary battery, comprising:
the lithium metal composite oxide powder according to claim 1 .
9 . A lithium secondary battery positive electrode containing the lithium secondary
8 . positive electrode active material according to claim 8 .
10 . A lithium secondary battery having the lithium secondary battery positive electrode according to claim 9 .
11 . The lithium metal composite oxide powder according to claim 2 ,
wherein a BET specific surface area is 2 m 2 /g or less.
12 . The lithium metal composite oxide powder according to claim 2 ,
wherein an average primary particle diameter is 0.3 μm or more and 8 μm or less.
13 . The lithium metal composite oxide powder according to claim 2 ,
wherein, in a 10% cumulative diameter (D 10 ), a 50% cumulative diameter (D 50 ), and a 90% cumulative diameter (D 90 ), all of which are obtained from particle size distribution measurement values, the 50% cumulative diameter (D 50 ) is 2 μm or more and 10 μm or less, and furthermore, a relationship of the following formula (B) is satisfied,
0.3≤( D 90 −D 10 )/ D 50 ≤3 (B).
14 . The lithium metal composite oxide powder according to claim 2 ,
wherein a value obtained by dividing a moisture content (mass %) by a BET specific surface area (m 2 /g) that is indicated by moisture content (mass %)/BET specific surface area (m 2 /g) is 0.005 or more and 0.7 or less.
15 . The lithium metal composite oxide powder according to claim 2 ,
wherein a maximum concentration gradient R Li/M in a range where the mole ratio between the element concentrations of Li and the element M that is indicated by Li/element M continuously increases from the particle surface to the particle center of the lithium metal composite oxide powder is small compared with a maximum concentration gradient R O/M in a range where the mole ratio between the element concentrations of O and the element M that is indicated by O/element M continuously increases from the particle surface to the particle center of the lithium metal composite oxide powder (R O/M >R Li/M ).
16 . A positive electrode active material for a lithium secondary battery, comprising:
the lithium metal composite oxide powder according to claim 2 .
17 . A lithium secondary battery positive electrode containing the lithium secondary battery positive electrode active material according to claim 16 .
18 . A lithium secondary battery having the lithium secondary battery positive electrode according to claim 17 .