Metal-doped cobalt precursor for preparing positive electrode active material for secondary battery
Provided is a cobalt precursor for preparing a lithium cobalt oxide of a layered structure which is included in a positive electrode active material, wherein the cobalt precursor is cobalt oxyhydroxide (CoM′OOH) doped with, as dopants, magnesium (Mg) and M′ different from the magnesium.
1. A cobalt precursor for preparing a lithium cobalt oxide of a layered structure which is included in a positive electrode active material, wherein the cobalt precursor is
cobalt oxyhydroxide represented by the chemical formula (Co x Mg y M′ z )OOH,
wherein x, y, and z satisfy the following weight ratio conditions: a content of x is in the range of 99 wt % to 99.8 wt % and a total content of y and z is in the range of 0.2 wt % to 1 wt %, when the sum of x, y, and z is regarded as 100 wt %;
M′ is one or more selected from the group consisting of Al, Ti, Mn, Zr, Ba, B, Ca, Ta, Mo, Nb, W, Sr and PO 4 ,
wherein the cobalt precursor is doped with, as dopants, magnesium (Mg) and M′.
2. A method of preparing a lithium cobalt oxide using the cobalt precursor, the method comprising:
(a) preparing the cobalt precursor of claim 1 which is doped with dopants provided from a doping precursor by co-precipitation reaction of a cobalt acid salt and the doping precursor; and
(b) mixing the dopant-doped cobalt precursor and a lithium precursor to form a mixture;
(c) heat treating the mixture.
3. The method of claim 2 , wherein the doping precursor is mixed such that a content of the cobalt is in the range of 99 wt % to 99.8 wt %, and a total content of the dopants is in the range of 0.2 wt % to 1 wt %, when the sum of the cobalt and the dopants is regarded as 100 wt %.
4. The method of claim 2 , wherein the heat treating is performed at 950° C. to 1100° C. for 8 hours to 15 hours.
5. The method of claim 2 , wherein the cobalt acid salt is cobalt oxyhydroxide represented by the chemical formula CoOOH.
6. The method of claim 2 , wherein the lithium precursor is one or more selected from the group consisting of Li 2 CO 3 , LiOH, LiNO 3 , CH 3 COOLi, and Li 2 (COO) 2 .
7. The method of claim 2 , wherein the doping precursor includes:
one or more selected from the group consisting of a mixed metal of Mg, and
one or more selected from the group consisting of Al, Ti, Mn, Zr, Ba, B, Ca, Ta, Mo, Nb, W, Sr, and P, a metal oxide thereof, and a metal salt thereof.