Transition metal-containing hydroxide, and method for producing lithium-containing composite oxide
To provide a transition metal-containing hydroxide, which is a precursor of a lithium-containing composite oxide, with which it is possible to obtain a lithium ion secondary battery excellent in the discharge capacity and cycle characteristics, by using as a cathode active material a lithium-containing composite oxide obtained from the hydroxide. A transition metal-containing hydroxide, which is a precursor of a lithium-containing composite oxide, wherein in a distribution of the logarithmic derivative pore specific surface area relative to the pore size, obtained by BJH method, the proportion of the sum of the logarithmic derivative pore specific surface areas with pore sizes of 10 nm or larger, to 100% of the sum of the logarithmic derivative pore specific surface areas in the entire distribution, is at least 23%.
1. A transition metal-containing hydroxide, which is a precursor of a lithium-containing composite oxide, wherein in a distribution of a logarithmic derivative pore specific surface area relative to pore size, obtained by a Barrett, Joyner, Halenda (BJH) method, a proportion of a sum of the logarithmic derivative pore specific surface areas with pore sizes of 10 nm or larger, to 100% of a sum of the logarithmic derivative pore specific surface areas in an entire distribution, is at least 23% and at most 33.7%;
wherein the transition metal-containing hydroxide has a BET specific surface area from 55 m 2 /g to 200 m 2 /g, and
wherein in a distribution of the logarithmic derivative pore specific surface area relative to the pore size, obtained by the BJH method, the sum of the logarithmic derivative pore specific surface areas with pore sizes of 10 nm or larger, is at least 300 m 2 /g and at most 400 m 2 /g.
2. The transition metal-containing hydroxide according to claim 1 , which is a transition metal-containing hydroxide represented by the following formula (1):
Ni α Co β Mn γ M δ (OH) 2 formula (1)
wherein M is a metal element other than Li, Ni, Co and Mn, α is from 0.15 to 0.5, β is from 0 to 0.2, γ is from 0.3 to 0.8, δ is from 0 to 0.1, and α+β+γ+δ=1.
3. The transition metal-containing hydroxide according to claim 1 , wherein D 50 of the transition metal-containing hydroxide is from 3.5 to 15.5 μm.
4. The transition metal-containing hydroxide according to claim 1 , wherein the transition metal-containing hydroxide has a BET specific surface area from 70 m 2 /g to 100 m 2 /g.
5. The transition metal-containing hydroxide according to claim 1 , wherein D 50 of the transition metal-containing hydroxide is from 3.5 to 8.0 μm.
6. A method for producing a lithium-containing composite oxide, which comprises a step of mixing the transition metal-containing hydroxide as defined in claim 1 and a lithium compound, and firing the mixture at 900° C. or higher.