Transition metal-containing hydroxide, and method for producing lithium-containing composite oxide

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 m2/g to 200 m2/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 m2/g and at most 400 m2/g.