Lithium metal composite oxide, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, and lithium secondary battery
An object of the present invention is to provide a lithium metal composite oxide, when used as a positive electrode active material for a lithium secondary battery, capable of obtaining a lithium secondary battery having a high cycle retention rate, and a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery in which the lithium metal composite oxide is used. This lithium metal composite oxide is a particulate lithium metal composite oxide, comprising first particles having a particle diameter equal to or less than a 50% cumulative volume particle size D 50 of the lithium metal composite oxide and second particles having a particle diameter exceeding the D 50 , in which the D 50 is 2 to 20 μm, an average particle strength P S of the first particles is larger than an average particle strength P B of the second particles, and a standard deviation σ S of the particle strength of the first particles is larger than a standard deviation σ B of the particle strength of the second particles.
1 . A lithium metal composite oxide of particle shape, comprising first particles having a particle diameter equal to or less than a 50% cumulative volume particle size D 50 of the lithium metal composite oxide and second particles having a particle diameter exceeding the D 50 ,
wherein the D 50 is 2 to 20 μm,
an average particle strength P S of the first particles is larger than an average particle strength P B of the second particles, and
a standard deviation σ S of the particle strength of the first particles is larger than a standard deviation σ B of the particle strength of the second particles.
2 . The lithium metal composite oxide according to claim 1 ,
wherein P S −P B , which is a difference between the P S and the P B , is 15 MPa or more.
3 . The lithium metal composite oxide according to claim 1 ,
wherein σ S −σ B , which is a difference between the σ S and the σ B , is 5 MPa or more.
4 . The lithium metal composite oxide according to claim 1 ,
wherein the P S is 50 to 110 MPa.
5 . The lithium metal composite oxide according to claim 1 ,
wherein the P B is 20 to 60 MPa.
6 . The lithium metal composite oxide according to claim 1 ,
wherein the σ S is 20 to 90 MPa.
7 . The lithium metal composite oxide according to claim 1 ,
wherein the σ B is 10 to 30 MPa.
8 . The lithium metal composite oxide according to claim 1 ,
wherein a BET specific surface area is 0.1 to 2.0 m 2 /g.
9 . 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 X z ) 1-x ]O 2 (I),
and in the formula (I), X represents one or more elements 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≤0.4, and 0<z≤0.5 are satisfied.
10 . The lithium metal composite oxide according to claim 9 ,
wherein the composition formula (I) satisfies 0<y+z≤0.3.
11 . A positive electrode active material for a lithium secondary battery, comprising:
the lithium metal composite oxide according to claim 1 .
12 . A positive electrode for a lithium secondary battery, comprising:
the positive electrode active material for the lithium secondary battery according to claim 11 .
13 . A lithium secondary battery, comprising:
the positive electrode for the lithium secondary battery according to claim 12 .