Composite positive active material, positive electrode and lithium battery containing the composite positive active material

1. A composite positive active material comprising a composite, the composite comprising:

a first metal oxide having a layered crystal structure; and

a second metal oxide having a rocksalt crystal structure,

wherein the second metal oxide is intermixed within the layered crystal structure of the first metal oxide, and

wherein the composite comprises at least one doping element selected from Group 1 and Group 2 of the Periodic Table wherein the doping element is not Li.

2. The composite positive active material of claim 1 , wherein the second metal oxide comprises at least one metal element selected from Group 8, Group 9, Group 10, Group 11, and Group 12 of the Periodic Table.

3. The composite positive active material of claim 2 , wherein the metal element is at least one selected from Ni, Co, Mn, Fe, Cu, and Cr.

4. The composite positive active material of claim 1 , wherein the second metal oxide has a composition represented by Formula 1:

AO  Formula 1

wherein, in Formula 1, A is at least one metal selected from Ni, Co, Fe, Cu, Zn, Ca, Sr, Mg, and Cr.

5. The composite positive active material of claim 1 , wherein an amount of the second metal oxide is from greater than 0 mole percent to about 20 mole percent, based on a total number of moles of the first metal oxide and the second metal oxide in the composite positive active material.

6. The composite positive active material of claim 1 , wherein the doping element is at least one element selected from Na, K, Ca, and Ba.

7. The composite positive active material of claim 1 , wherein the first metal oxide comprises lithium, and

wherein an amount of the doping element is greater than 0 mole percent to about 20 mole percent, based on a total number of moles of Li in the first metal oxide.

8. The composite positive active material of claim 1 , wherein the first metal oxide comprises the doping element.

9. The composite positive active material of claim 1 , wherein the first metal oxide has a composition represented by at least one of Formulae 2 and 3:

[Li 1-a A′ a ]MeO 2   Formula 2

wherein, in Formula 2,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table, and is not Li,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt, and

0<a≤0.2, and

v [Li 2-b A′ b ][M 1-c A′ c ]O 3 .w [Li 1-d A′ d ][Me 1-e A′ e ]O 2   Formula 3

wherein, in Formula 3,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table and is not Li,

M is at least one metal selected from Al, Ga, Ge, Mg, Nb, Zn, Cd, Ti, Co, Ni, K, Na, Ca, Si, Fe, Cu, Sn, V, B, P, Se, Bi, As, Zr, Re, Ru, Mn, Cr, Sr, Sc, Y, and a rare earth metal,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt,

0<v<1, 0<w<1, v+w=1, 0≤b<1, 0≤c<1, 0≤d<1, 0≤e<1, and 0<A′/Li≤0.2,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

10. The composite positive active material of claim 1 , wherein the first metal oxide has a composition represented by Formula 2a:

[Li 1-a A′ a ](Ni p Co q Mn r )O 2   Formula 2a

wherein, in Formula 2a, A′ is at least one element selected from Na, K, Ca, and Ba, 0≤p≤1, 0≤q≤1, 0≤r≤1, p+q+r=1, and 0<a≤0.2.

11. The composite positive active material of claim 1 , wherein the first metal oxide has a composition represented by Formula 3a:

v [Li 2-b A′ b ] 2 MO 3 .w [Li 1-d A′ d ]MeO 2   Formula 3a

wherein, in Formula 3a,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table and is not Li,

M is at least one metal selected from Al, Ga, Ge, Mg, Nb, Zn, Cd, Ti, Co, Ni, K, Na, Ca, Si, Fe, Cu, Sn, V, B, P, Se, Bi, As, Zr, Re, Ru, Mn, Cr, Sr, Sc, Y, and a rare earth element,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt,

0<v<1, 0<w<1, v+w=1, 0≤b<1, 0≤d<1, and 0<A′/Li≤0.2,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

12. The composite positive active material of claim 1 , wherein the first metal oxide has a composition represented by Formula 3b:

v [Li 2-b A′ d ] 2 MnO 3 .w [Li 1-d A′ d ](Ni p Co q Mn r )O 2   Formula 3b

wherein, in Formula 3b,

A′ is at least one element selected from Na, K, Ca, and Ba,

0<v<1, 0<w<1, v+w=1, 0≤p≤1, 0≤q≤1, 0≤r≤1, p+q+r=1, 0≤b<1, and 0≤d<1, and 0<A′/Li≤0.2,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

13. The composite positive active material of claim 1 , wherein the first metal oxide comprises a plurality of crystalline phases, and wherein the first metal oxide is a composite of the plurality of crystalline phases.

14. The composite positive active material of claim 1 , wherein first metal oxide having the layered crystal structure and second metal oxide having the rocksalt structure are homogenously distributed in the composite positive active material.

15. A positive electrode comprising the composite positive active material of claim 1 .

16. A lithium battery comprising the positive electrode of claim 15 .

17. A composite positive active material of claim 1 , comprising a composite, the composite comprising:

a first metal oxide having a layered crystal structure; and

a second metal oxide having a rocksalt crystal structure,

wherein the composite comprises at least one doping element selected from Group 1 and Group 2 of the Periodic Table wherein the doping element is not Li, and

wherein the composite positive active material has a composition represented by at least one of Formulae 4 and 5:

x [Li 1-a A′ a ]MeO 2 .y AO  Formula 4

wherein, in Formula 4,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt,

A is at least one metal selected from Ni, Co, Fe, Cu, Zn, Ca, Sr, Mg, and Cr;

0<x<1, 0<y<0.2, x+y=1, and 0<a≤0.2, and

x [Li 2-b A′ b ][M 1-c A′ c ]O 3 .y [Li 1-d A′ d ][Me 1-e A′ e ]O 2 .z AO  Formula 5

wherein, in Formula 5,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table,

M is at least one metal selected from Al, Ga, Ge, Mg, Nb, Zn, Cd, Ti, Co, Ni, K, Na, Ca, Si, Fe, Cu, Sn, V, B, P, Se, Bi, As, Zr, Re, Ru, Mn, Cr, Sr, Sc, Y, and a rare earth element,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt,

A is at least one metal selected from Ni, Co, Fe, Cu, Zn, Ca, Sr, Mg, and Cr,

0<x<1, 0<y<1, 0<z<0.2, x+y+z=1, 0≤b<1, 0≤c<1, 0≤d<1, 0≤e<1, and 0<A′/Li≤0.2,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

18. The composite positive active material of claim 17 , wherein the composite positive active material has a composition represented by Formula 4a:

x [Li 1-a A′ a ](Ni p Co q Mn r )O 2 .y AO  Formula 4a

wherein, in Formula 4a,

A′ is at least one element selected from Na, K, Ca, and Ba,

0<x<1, 0<y<0.2, x+y=1, 0<a≤0.2, 0≤p≤1, 0≤q≤1, 0≤r≤1, and p+q+r=1.

19. The composite positive active material of claim 17 , wherein the composite positive active material has a composition represented by Formula 5a:

x [Li 2-b A′ b ] 2 MO 3 .y [Li 1-d A′ d ]MeO 2 .z AO  Formula 5a

wherein, in Formula 5a,

A′ is at least one element selected from Group 1 and Group 2 of the Periodic Table and is not Li,

M is at least one metal selected from Al, Ga, Ge, Mg, Nb, Zn, Cd, Ti, Co, Ni, K, Na, Ca, Si, Fe, Cu, Sn, V, B, P, Se, Bi, As, Zr, Re, Ru, Mn, Cr, Sr, Sc, Y, and a rare earth element,

Me is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, Mo, and Pt,

A is at least one metal selected from Ni, Co, Fe, Cu, Zn, Ca, Sr, Mg, and Cr,

0<x<1, 0<y<1, 0<z<0.2, x+y+z=1, 0≤b<1, 0≤d<1, and 0<A′/Li≤0.2,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

20. The composite positive active material of claim 17 , wherein the composite positive active material has a composition represented by Formula 5b:

x [Li 2-b A′ b ] 2 MnO 3 .y [Li 1-d A′ d ](Ni p Co q Mn r )O 2 .z AO  Formula 5b

wherein, in Formula 5b,

A′ is at least one metal selected from Na, K, Ca, and Ba,

A is at least one metal selected from Ni, Co, Fe, Cu, Zn, Ca, Sr, Mg, and Cr,

0<x<1, 0<y<1, 0<z<0.2, x+y+z=1, 0≤p≤1, 0≤q≤1, 0≤r≤1, p+q+r=1, 0≤b<1, 0≤d<1, and 0<A′/Li≤0.3,

wherein A′/Li is a molar ratio of A′ and Li in the composite positive active material.

21. The composite positive active material of claim 17 , wherein the second metal oxide is intermixed within the layered crystal structure of the first metal oxide.