Lithium cobalt composite oxide for lithium secondary battery and lithium secondary battery including positive electrode including the lithium cobalt composite oxide
A lithium cobalt composite oxide for a lithium secondary battery and a lithium secondary battery, the lithium cobalt composite oxide being doped with magnesium and having an atomic ratio of Mg/Co of about 0.0035:1 to about 0.01:1.
1. A lithium cobalt composite oxide for a lithium secondary battery, the lithium cobalt composite oxide being doped with magnesium and having an atomic ratio of Mg/Co of the lithium cobalt composite oxide of about 0.005:1 to about 0.0075:1,
wherein the lithium cobalt composite oxide is a compound represented by Formula 1:
Li 1-x Mg x Co 1-y M y O 2 [Formula 1]
wherein, in Formula 1,
0.005<x<0.007653 and 0≤y<0.02; and
M is titanium (Ti), vanadium (V), nickel (Ni), iron (Fe), niobium (Nb), aluminum (Al), zirconium (Zr), or manganese (Mn).
2. The lithium cobalt composite oxide as claimed in claim 1 , wherein the lithium cobalt composite oxide is Li 0.9925 Mg 0.0075 CoO 2 , or Li 0.995 Mg 0.005 CoO 2 .
3. A lithium secondary battery comprising a positive electrode that includes a lithium cobalt composite oxide, the lithium cobalt composite oxide being doped with magnesium and having an atomic ratio of Mg/Co of about 0.005:1 to about 0.0075:1,
wherein the lithium cobalt composite oxide is a compound represented by Formula 1:
Li 1-x Mg x Co 1-y M y O 2 [Formula 1]
wherein, in Formula 1,
0.005<x<0.007653 and 0≤y<0.02; and
M is titanium (Ti), vanadium (V), nickel (Ni), iron (Fe), niobium (Nb), aluminum (Al), zirconium (Zr), or manganese (Mn).
4. The lithium secondary battery as claimed in claim 3 , wherein a charging voltage of the lithium secondary battery is 4.5 V or higher.
5. The lithium secondary battery as claimed in claim 3 , wherein the lithium cobalt composite oxide is Li 0.9925 Mg 0.0075 CoO 2 , Li 0.995 Mg 0.005 CoO 2 ,or Li 0.99325 Mg 0.00625 CoO 2 .