Composite positive active material, positive electrode including the same, and lithium battery including the positive electrode

1. A composite positive active material comprising a composite represented by Formula 1:

δLi 2 MO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a CO b M′ c O 2 ]  Formula 1

wherein, in Formula 1,

M is Ti or Zr;

M′ is Mn, V, Mg, Ga, Si, W, Mo, Fe, Cr, Cu, Zn, Ti, Al, B, or a combination thereof;

0<δ<0.5; 0≤x<0.3; a+b+c≤1; 0<a<1; 0<b<1; 0<c<1; and 0.95≤d≤1.05.

2. The composite positive active material of claim 1 , wherein, in Formula 1, 0<δ<0.1, and 0<x<0.1.

3. The composite positive active material of claim 1 , wherein, in Formula 1, 0<δ<0.05, and 0<x<0.05.

4. The composite positive active material of claim 1 , wherein, in Formula 1, M′ is Mn, Al, or a combination thereof.

5. The composite positive active material of claim 1 , wherein the compound represented by Formula 1 is a compound represented by Formula 2, a compound represented by Formula 3, a compound represented by Formula 4, or a compound represented by Formula 5:

δLi 2 TiO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a CO b Mn c O 2 ]  Formula 2

wherein, in Formula 2, 0<δ<0.1, 0≤x<0.1, a+b+c≤1, 0<a<1, 0<b<1, 0<c<1, and 0.95≤d≤1.05,

δLi 2 ZrO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a Co b Mn c O 2 ]  Formula 3

wherein, in Formula 3, 0<δ<0.1, 0≤x<0.1, a+b+c≤1, 0<a<1, 0<b<1, and 0<c<1, and 0.95≤d≤1.05,

δLi 2 TiO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a Co b Al c O 2 ]  Formula 4

wherein, in Formula 4, 0<δ<0.1, 0≤x<0.1, a+b+c≤1, 0<a<1, 0<b<1, and 0<c<1, and 0.95≤d≤1.05, and

δLi 2 ZrO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a Co b Al c O 2 ]  Formula 5

wherein, in Formula 5, 0<δ<0.1, 0≤x<0.1, a+b+c≤1, 0<a<1, 0<b<1, and 0<c<1, and 0.95≤d≤1.05.

6. The composite positive active material of claim 1 , wherein, in Formula 1, δ is from 0.01 to 0.03.

7. The composite positive active material of claim 1 , wherein, in Formula 1, a is from 0.7 to 0.95, b is from 0.01 to 0.15, c is 0.01 to 0.15, and d is 0.99 to 1.04.

8. The composite positive active material of claim 1 , wherein, in Formula 1, a molar ratio of Li to a total content of transition metal is from about 1.015 to about 1.055, wherein the transition metal comprises each of M, Mn, Ni, Co, and M′.

9. The composite positive active material of claim 1 , wherein the composite represented by Formula 1 is

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985Li 0.99 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985Li 0.99 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985Li 0.99 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985LiNi 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985LiNi 0.91 Co 0.06 Mn 0.015 O 2 ];

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985LiNi 0.91 Co 0.06 Mn 0.015 O 2 ];

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985Li 1.01 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985Li 1.01 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985Li 1.01 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985Li 1.02 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985Li 1.02 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985Li 1.02 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985Li 1.03 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985Li 1.03 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985Li 1.03 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.01Li 2 TiO 3 .0.99[0.015Li 2 MnO 3 .0.985Li 1.04 Ni 0.91 Co 0.06 Mn 0.015 O 2 ];

0.02Li 2 TiO 3 .0.98[0.015Li 2 MnO 3 .0.985Li 1.04 Ni 0.91 Co 0.06 Mn 0.015 O 2 ]; or

0.03Li 2 TiO 3 .0.97[0.015Li 2 MnO 3 .0.985Li 1.04 Ni 0.91 Co 0.06 Mn 0.015 O 2 ].

10. The composite positive active material of claim 1 , wherein the composite positive active material has a first peak corresponding to Li 2 TiO 3 at about 0 parts per million, and a second peak at about 200 parts per million to about 1500 parts per million, when analyzed by lithium solid-state nuclear magnetic resonance spectroscopy.

11. The composite positive active material of claim 1 , wherein the composite positive active material has an intensity ratio of a peak of a 003 face to a peak of a 104 face of about 1.54 to about 1.64, when analyzed by X-ray diffraction analysis with Cu-Kα radiation.

12. The composite positive active material of claim 1 , wherein, the composite positive active material has a peak having a diffraction angle of about 18° 2-theta to about 19° 2-theta and a full width at half maximum of about 0.2° to about 0.28°, when analyzed by X-ray diffraction.

13. The composite positive active material of claim 1 , wherein the composite positive active material comprises a primary particle having a size of from about 100 nanometers to about 300 nanometers.

14. The composite positive active material of claim 1 , wherein the composite positive active material comprises a coating layer on a surface thereof, the coating layer comprising a conductive material, a metal oxide, an inorganic fluoride, or a combination thereof.

15. The composite positive active material of claim 14 , wherein the conductive material comprises a carbonaceous material, indium tin oxide, RuO 2 , ZnO, or a combination thereof.

16. The composite positive active material of claim 14 , wherein the metal oxide comprises silica, alumina, zirconium oxide, titanium oxide, or a combination thereof.

17. The composite positive active material of claim 14 , wherein the organic fluoride comprises AlF 3 , CsF, KF, LiF, NaF, RbF, AgF, AgF, BaF 2 , CaF 2 , CuF 2 , CdF 2 , FeF 2 , HgF 2 , Hg 2 F 2 , MnF 2 , MgF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , BF 3 , BiF 3 , CeF 3 , CrF 3 , DyF 3 , EuF 3 , GaF 3 , GdF 3 , FeF 3 , HoF 3 , InF 3 , LaF 3 , LuF 3 , MnF 3 , NdF 3 , VOF 3 , PrF 3 , SbF 3 , ScF 3 , SmF 3 , TbF 3 , TiF 3 , TmF 3 , YF 3 , YbF 3 , TlF 3 , CeF 4 , GeF 4 , HfF 4 , SiF 4 , SnF 4 , TiF 4 , VF 4 , ZrF 4 , NbF 5 , SbF 5 , TaF 5 , BiF 5 , MoF 6 , ReF 6 , SF 6 , WF 6 , or a combination thereof.

18. The composite positive active material of claim 1 , wherein the Li 2 MO 3 is electrochemically inactive with respect to lithium in a voltage range of about 4.0 volts to about 4.5 volts versus Li/Li + .

19. The composite positive active material of claim 1 , wherein the composite is represented by Formula 6:

δLi 2 MO 3 .(1−δ)Li d Ni a CO b M′ c O 2   Formula 6

wherein, in Formula 6,

M is Ti or Zr,

M′ is Mn, V, Mg, Ga, Si, W, Mo, Fe, Cr, Cu, Zn, Ti, Al, B, or a combination thereof;

0<δ<0.5; a+b+c=1; 0<a<1; 0<b<1; 0<c<1; and 1<d≤1.05.

20. A positive electrode comprising a composite positive active material comprising a composite represented by Formula 1:

δLi 2 MO 3 .(1−δ)[ x Li 2 MnO 3 .(1 −x )Li d Ni a CO b M′ c O 2 ]  Formula 1

wherein, in Formula 1,

M is Ti or Zr,

M′ is Mn, V, Mg, Ga, Si, W, Mo, Fe, Cr, Cu, Zn, Ti, aluminum (Al), B, or a combination thereof, and

0<δ<0.5, 0≤x<0.3, a+b+c≤1, 0<a<1, 0<b<1, 0<c<1, and 0.95≤d≤1.05.

21. A lithium battery comprising:

the positive electrode of claim 20 ,

a negative electrode, and

an electrolyte disposed between the positive electrode and the negative electrode.

22. The lithium battery of claim 21 , wherein the lithium battery has a voltage of about 4.5 volts or greater.

23. The lithium battery of claim 21 , wherein the negative electrode comprises a lithium metal electrode or a lithium metal alloy electrode; or the negative electrode comprises a negative electrode active material comprising a carbonaceous material, silicon, silicon oxide, a silicon alloy, a silicon-carbon composite, Sn, an Sn-containing alloy, a Sn-carbon composite, a metal oxide, or a combination thereof.