Precursor for the preparation of a lithium composite transition metal oxide

1. A transition metal precursor comprising a composite transition metal compound represented by Formula 1, as a transition metal precursor used in the preparation of a lithium-transition metal composite oxide:

M(OH 1−x ) 2   (1)

wherein:

M is two or more selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr and the transition metals of 2 period in the Periodic Table of the Elements; and

0<x<0.5.

2. The transition metal precursor according to claim 1 , wherein an oxidation number of the M in Formula 1 approximates to an oxidation number of a transition metal in the lithium-transition metal composite oxide.

3. The transition metal precursor according to claim 2 , wherein an oxidation number of the M in Formula 1 approximates to +3.

4. The transition metal precursor according to claim 1 , wherein the x in Formula 1 has a value of 0.2≦x<0.5.

5. The transition metal precursor according to claim 1 , wherein the x in Formula 1 has a value of 0.3≦x<0.5.

6. The transition metal precursor according to claim 1 , wherein the M contains one or more transition metals selected from the group consisting of Ni, Co and Mn.

7. The transition metal precursor according to claim 6 , wherein the M contains two transition metals selected from the group consisting of Ni, Co and Mn or all of them.

8. The transition metal precursor according to claim 1 , wherein the composite transition metal compound is a composite transition metal compound represented by Formula 2:

Ni b Mn c Co 1−(b+c+d) M′ d (OH 1−x ) 2   (2)

wherein:

0.3≦b≦0.9;

0.1≦c≦0.6;

0≦d≦0.1;

b+c+d≦1;

0<x<0.5; and

M′ is selected from the group consisting of Al, Mg, Cr, Ti, Si and any combination thereof.

9. The transition metal precursor according to claim 1 , wherein the composite transition metal compound has a content of 30% by weight or higher, based on the total weight of the transition metal precursor.

10. The transition metal precursor according to claim 9 , wherein the composite transition metal compound has a content of 50% by weight or higher, based on the total weight of the transition metal precursor.

11. A composite transition metal compound represented by Formula 1:

M(OH 1−x ) 2   (1)

wherein M and x are as defined in claim 1 .

12. A lithium-transition metal composite oxide prepared by using the transition metal precursor of claim 1 .

13. A lithium secondary battery comprising the lithium-transition metal composite oxide of claim 12 as a cathode active material.