Composite cathode active material, cathode and lithium battery containing the composite cathode active material

1. A composite cathode active material comprising:

a first metal oxide having a layered crystal structure; and

a second metal oxide having a perovskite crystal structure,

wherein the second metal oxide comprises a first metal and a second metal that are each 12-fold cuboctahedrally coordinated to oxygen, and

wherein the composite cathode active material is a composition represented by Formula 3:

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 [A 1-a A′ a ]M 1 O 3   Formula 3

wherein, in Formula 3,

A is the first metal and is selected from La, Sr, Ba, Ce, Y, and Sc,

A′ is the second metal and is selected from Li, Na, Ca, Ag, K, Mg, and Cu,

M 1 is at least one metal selected from Mn, V, Cr, Fe, Co, Ni, Zr, Ti, Mg, Cu, Nb, Ta, Ru, W, and Sn,

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<x<1, 0<y<1, 0.025≦z<0.1, and x+y+z=1, and

0<a≦0.3, 0≦b<1, 0≦c<1, 0≦d<1, 0≦e<1, 0<a+b+c+d+e<0.3, and 0≦A′/Li<0.3,

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

2. The composite cathode active material of claim 1 , wherein the first metal is selected from elements belonging to Group 2 and Group 3 of the Periodic Table.

3. The composite cathode active material of claim 2 , wherein the first metal is selected from La, Sr, Ba, Ce, Y, and Sc.

4. The composite cathode active material of claim 1 , wherein the second metal is selected from elements belonging to Group 1 of the Periodic Table.

5. The composite cathode active material of claim 1 , wherein the second metal is Na.

6. The composite cathode active material of claim 1 , wherein the second metal oxide further comprises a third metal that is 6-fold octahedrally coordinated to oxygen.

7. The composite cathode active material of claim 6 , wherein the third metal is selected from elements belonging to Group 4, Group 5, Group, 6, Group 7, Group 8, Group 9, Group 10, Group 11, and Groups 12 to 14.

8. The composite cathode active material of claim 6 , wherein the third metal is selected from Mn, V, Cr, Fe, Co, Ni, Zr, Ti, Mg, Cu, Nb, Ta, Ru, W, and Sn.

9. The composite cathode active material of claim 1 , wherein the second metal oxide comprises at least one metal oxide selected from (La 1-a Na a )MnO 3 , (La 1-a Li a )MnO 3 , (Ba 1-a Na a )TiO 3 , (Ba 1-a Li a )TiO 3 , (La 1-a Na a )NiO 3 , (La 1-a Li a )NiO 3 , (La 1-a Na a )CoO 3 , (La 1-a Li a )CoO 3 , (La 1-a Na a )MgO 3 , (La 1-a Li a )MgO 3 , (La 1-a Na a )FeO 3 , (La 1-a Li a )FeO 3 , (Sr 1-a Na a )NiO 3 , (Sr 1-a Li a )NiO 3 , (Sr 1-a Na a )CoO 3 , (Sr 1-a Li a )CoO 3 , (Sr 1-a Na a )MnO 3 , (Sr 1-a Li a )MnO 3 , (Sr 1-a Na a )MgO 3 , (Sr 1-a Li a )MgO 3 , (Sr 1-a Na a )FeO 3 , (Sr 1-a Li a )FeO 3 , (Ba 1-a Na a )NiO 3 , (Ba 1-a Li a )NiO 3 , (Ba 1-a Na a )CoO 3 , (Ba 1-a Li a )CoO 3 , (Ba 1-a Na a )MnO 3 , (Ba 1-a Li a )MnO 3 , (Ba 1-a Na a )MgO 3 , (Ba 1-a Li a )MgO 3 , (Ba 1-a Na a )FeO 3 , (Ba 1-a Li a )FeO 3 , (Ca 1-a Na a )NiO 3 , (Ca 1-a Li a )NiO 3 , (Ca 1-a Na a )CoO 3 , (Ca 1-a Li a )CoO 3 , (Ca 1-a Na a )MnO 3 , (Ca 1-a Li a )MnO 3 , (Ca 1-a Na a )MgO 3 , (Ca 1-a Li a )MgO 3 , (Ca 1-a Na a )FeO 3 , and (Ca 1-a Li a )FeO 3 , wherein, in the metal oxides, 0<a≦0.3.

10. The composite cathode active material of claim 1 , wherein the first metal oxide comprises a plurality of crystal phases, and wherein a first crystal phase and a second crystal phase of the plurality of crystal phases have different compositions.

11. The composite cathode active material of claim 10 , wherein composite cathode active material comprises a composite phase comprising the plurality of crystal phases.

12. The composite cathode active material of claim 1 , wherein the composite cathode active material comprises a composite of the first metal oxide and the second metal oxide.

13. The composite cathode active material of claim 1 , wherein the second metal oxide is intermixed in the layered crystal structure of the first metal oxide.

14. The composite cathode active material of claim 1 having a composition represented by Formula 4:

x [Li 2-b A′ b ][Mn 1-c A′ c ]O 3 .y [Li 1-d A′ d ][(Ni p Co q Mn r ) 1-e A′ e ]O 2 .z [La 1-a A′ a ]MnO 3   Formula 4

wherein, in Formula 4,

A′ is a metal selected from Li, Na, Ca, Ag, K, Mg, and Cu,

0<x<1, 0<y<1, 0.025≦z<0.1, and x+y+z=1,

0<p<1, 0<q<1, 0<r<1, and p+q+r=1, and

0<a≦0.3, 0≦b<1, 0≦c<1, 0≦d<1, 0≦e<1, 0<a+b+c+d+e<0.3, and 0≦A′/Li<0.3,

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

15. The composite cathode active material of claim 1 having a composition represented by Formula 5:

x [Li 2-b Na b ][Mn 1-c Na c ]O 3 .y [Li 1-d Na d ][(Ni p Co q Mn r ) 1-e Na e ]O 2 .z [La 1-a Na a ]MnO 3   Formula 5

wherein, in Formula 5,

0<x<1, 0<y<1, 0.025≦z<0.1, and x+y+z=1,

0<p<1, 0<q<1, 0<r<1, and p+q+r=1, and

0<a≦0.3, 0≦b<1, 0≦c<1, 0≦d<1, 0≦e<1, 0<a+b+c+d+e<0.3, and 0≦Na/Li<0.3,

wherein Na/Li is a ratio of a mole ratio of Na and Li in the composite cathode active material.

16. A cathode comprising the composite cathode active material of claim 1 .

17. A lithium battery comprising the cathode of claim 16 .