Transition metal composite hydroxide and lithium composite metal oxide

1. A transition metal mixed hydroxide containing an alkali metal other than Li, SO 4 and a transition metal element, wherein the molar ratio of the molar content of all of the alkali metal other than Li to the molar content of the SO 4 is not less than 1 and less than 2, and the molar ratio of the molar content of the alkali metal to the molar content of the transition metal mixed hydroxide is 0.00001 to 0.003.

2. The transition metal mixed hydroxide according to claim 1 , wherein the transition metal element represents Ni, Mn and Fe.

3. The transition metal mixed hydroxide according to claim 2 , wherein the molar ratio of Ni:Mn:Fe is (1−x−y):x:y, wherein x is not less than 0.3 and not more than 0.7 and y is more than 0 and less than 0.2.

4. The transition metal mixed hydroxide according to claim 1 , wherein the alkali metal is K.

5. A method for producing a lithium mixed metal oxide, the method comprising calcining a mixture of the transition metal mixed hydroxide according to claim 1 and a lithium compound by maintaining the mixture at a temperature of 650 to 1000° C.

6. The method according to claim 5 , wherein the transition metal mixed hydroxide is obtained by a method comprising the following steps (1) and (2):

(1) a step of bringing an aqueous solution containing a transition metal element and SO 4 into contact with an alkali comprising an alkali metal other than Li to obtain a coprecipitate slurry,

(2) a step of obtaining a transition metal mixed hydroxide from the coprecipitate slurry.

7. The method according to claim 6 , wherein the aqueous solution is an aqueous solution obtained by dissolving a sulfate of Ni, a sulfate of Mn and a sulfate of Fe in water.

8. The method according to claim 7 , wherein the sulfate of Fe is a sulfate of divalent Fe.