Precursor for preparing lithium composite transition metal oxide and method for preparing the same
Disclosed is a transition metal precursor used for preparation of lithium composite transition metal oxide, the transition metal precursor comprising a composite transition metal compound represented by the following Formula 1: M(OH 1−x ) 2−y A y/n (1) wherein M comprises two or more selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr and second period transition metals; A comprises one or more anions except OH 1−x ; 0≦x≦0.5; 0.01≦y≦0.5; and n is an oxidation number of A. The transition metal precursor according to the present invention contains a specific anion. A lithium composite transition metal oxide prepared using the transition metal precursor comprises the anion homogeneously present on the surface and inside thereof, and a secondary battery based on the lithium composite transition metal oxide thus exerts superior power and lifespan characteristics, and high charge and discharge efficiency.
1. A transition metal precursor used for preparation of lithium composite transition metal oxide, the transition metal precursor comprising a composite transition metal compound represented by the following Formula 1:
M(OH 1−x ) 2−y A y/n (1)
wherein
M comprises two or more selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr, Ti and Zr;
A is PO 4 ;
0<x<0.5;
0.01≦y≦0.5; and
n is an oxidation number of A.
2. The transition metal precursor according to claim 1 , wherein M comprises two or more transition metals selected from the group consisting of Ni, Co and Mn.
3. The transition metal precursor according to claim 1 , wherein the composite transition metal compound is a composite transition metal compound represented by the following Formula 2:
Ni b Mn c Co 1−(b+c+d) M′ d (OH 1−x ) 2−y A y/n (2)
wherein
0.3≦b≦0.9;
0.1≦c≦0.6;
0≦d≦0.1;
b+c+d≦1;
M′ comprises one, or two or more selected from the group consisting of Al, Mg, Cr, Ti, Cu, Fe and Zr; and
A, x, and y and n are as defined in claim 1 .
4. The transition metal precursor according to claim 1 , wherein the composite transition metal compound has a tap density of 1.5 to 2.5 g/cc.
5. The transition metal precursor according to claim 1 , wherein the composite transition metal compound is present in an amount of 30% by weight or more, based on the total amount of the transition metal precursor.
6. A method for preparing the composite transition metal compound represented by Formula 1 according to claim 1 , the method comprising reacting a transition metal salt for preparing a precursor with 0.01 to 0.5 mol% of Z x ′A y ′,
wherein Z comprises at least one selected from the group consisting of Na, NH 4 and H;
A is PO 4 ; and
an equation of an oxidation number of (an oxidation number of Z×x′)+(an oxidation number of A×y′)=0 is satisfied, with the proviso that 0<x′<4 and 0<y′<4.
7. The method according to claim 6 , wherein the transition metal salt for preparing a precursor is sulfate.
8. The method according to claim 7 , wherein the sulfate is at least one selected from the group consisting of nickel sulfate, cobalt sulfate and manganese sulfate.
9. The method according to claim 6 , wherein the Z x ′A y ′ is at least one selected from the group consisting of Na 3 PO 4 , (NH 4 ) 3 PO 4 , (NH 4 ) 2 HPO 4 , and (NH 4 )H 2 PO 4 .
10. The method according to claim 6 , wherein the Z x ′A y ′ is added to a reactor after being dissolved in water or sodium hydroxide.