Cobalt composite hydroxide and preparation method thereof, lithium ion battery positive electrode material and lithium ion battery

The invention relates to the field of lithium ion batteries, in particular to cobalt composite hydroxide and a preparation method thereof, a lithium ion battery positive electrode material and a lithium ion battery. The chemical formula of the cobalt composite hydroxide is Ni < x > Co < y > Mn < z > (OH) < 2 >, x + y + z = 1, x is smaller than or equal to 0.1, y is larger than or equal to 0.9, z is smaller than or equal to 0.1, and x and z are not 0 at the same time; the ratio of the 100 active crystal face in the cobalt composite hydroxide is 10%-40%. By doping Ni and/or Mn, the structural stability of the cobalt composite hydroxide can be effectively improved, the specific capacity and the cycle capacity retention ratio of the battery are improved, and the cost is reduced; by exposing the 100 active crystal face in a large area and covering the 001 inactive face, the rate capability of the positive electrode material obtained after sintering can be improved, the contact area between the positive electrode m