Precursor for preparation of lithium composite transition metal oxide and method of preparing the same
Disclosed are a transition metal precursor for preparation of a lithium composite transition metal oxide, the transition metal precursor including a composite transition metal compound represented by Formula 1 below and a hydrocarbon compound, and a method of preparing the same: Mn a M b (OH 1-x ) 2 (1) wherein M is at least two selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr, and second period transition metals; 0.4≦a≦1; 0≦b≦0.6; a+b≦1; and 0≦x≦0.5, in which the transition metal precursor includes a particular composite transition metal compound and a hydrocarbon compound, and thus, when a lithium composite transition metal oxide is prepared using the same, carbon may be present in lithium transition metal oxide particles and/or on surfaces thereof, whereby a secondary battery including the lithium composite transition metal oxide exhibits excellent rate characteristics and long lifespan.
1. A transition metal precursor for preparation of a lithium composite transition metal oxide, the transition metal precursor comprising a composite transition metal compound represented by Formula 1 below and a hydrocarbon compound:
Mn a M b (OH 1-x ) 2 (1)
wherein M is at least two selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr, Ti and Zr;
0.4≦a≦1;
0≦b≦0.6;
a+b≦1; and
0<x<0.5,
wherein an amount of the hydrocarbon compound is in a range of 0.1 to 10 wt % based on a total amount of the transition metal precursor, wherein the transition metal precursor has closed pores, and at least a portion of the hydrocarbon compound is contained in the closed pores.
2. The transition metal precursor according to claim 1 , wherein M is at least one transition metal selected from the group consisting of Ni and Co.
3. The transition metal precursor according to claim 1 , wherein 0.5≦a≦1.
4. The transition metal precursor according to claim 1 , wherein 0.1≦b≦0.5.
5. The transition metal precursor according to claim 1 , wherein the composite transition metal compound is a composite transition metal compound represented by Formula 2 below:
Mn a′ Ni c Co 1-(a′+c+d) M′ d (OH 1-x ) 2 (2)
wherein 0.6≦a′≦1;
0.1≦c≦0.5;
0≦d≦0.1;
a′+c+d≦1;
M′ is at least one selected from the group consisting of Al, Mg, Cr, Ti, Cu, Fe, and Zr; and
x is the same as defined in claim 1 .
6. The transition metal precursor according to claim 1 , wherein an amount of the composite transition metal compound is 30 wt % or greater based on a total amount of the transition metal precursor.
7. The transition metal precursor according to claim 1 , wherein the hydrocarbon compound is a saccharide-based material.
8. The transition metal precursor according to claim 7 , wherein the saccharide-based material is at least one selected from the group consisting of fructose, sucrose, glucose, galactose, lactose, maltose, starch, and dextrin.
9. The transition metal precursor according to claim 8 , wherein the saccharide-based material is sucrose.
10. The transition metal precursor according to claim 1 , wherein the hydrocarbon compound is present in the transition metal precursor and/or on a surface thereof.
11. A method of preparing the transition metal precursor according to claim 1 , the method comprising:
preparing an aqueous transition metal solution containing a transition metal salt for preparation of the transition metal precursor;
mixing a hydrocarbon compound into the aqueous transition metal solution in an amount of 0.01 to 10 mol % based on a total amount of the aqueous transition metal solution; and
performing co-precipitation by adding a strong base to the mixed solution.
12. The method according to claim 11 , wherein the transition metal salt is a sulfate, and the strong base is sodium hydroxide.
13. The method according to claim 12 , wherein the sulfate is at least one selected from the group consisting of nickel sulfate, cobalt sulfate, and manganese sulfate.
14. A cathode active material prepared by mixing the transition metal precursor according to claim 1 and a lithium precursor and sintering the mixture in an oxidizing atmosphere.
15. The cathode active material according to claim 14 , wherein the cathode active material comprises lithium transition metal oxide particles and carbon present in the particles and/or on surfaces of the particles.
16. A lithium secondary battery comprising the cathode active material according to claim 14 .