Lithium-containing composite oxide and its production method
A lithium/nickel/cobalt/manganese-containing composite oxide powder represented by the formula Li p Ni x Co y Mn z M q O 2-a F a (wherein M is at least one element selected from the group consisting of Al, Ge, Sn, alkaline earth metal elements and transition metal elements other than Co, Mn and Ni, 0.9≦p≦1.1, 0.2≦x≦0.5, 0.2≦y≦0.5, 0.1≦z≦0.4, 0≦q≦0.5, 1.9≦a≦2.1, p+x+y+z+q=2, and 0≦a≦0.02), characterized in that when the powder is classified into small particle size-classified particles with an average particle size 2 μm≦D 50 ≦8 μm and large particle size-classified particles with an average particle size of 10 μm≦D 50 ≦75 μm, the ratio of (% by weight of the small particle size-classified particles)/(% by weight of the large particle size-classified particles) is from 15/85 to 40/60.
1. A lithium/nickel/cobalt/manganese-containing composite oxide powder represented by the formula Li p Ni x Co y Mn z M q O 2-a F a wherein M is at least one element selected from the group consisting of A1, Ge, Sn, alkaline earth metal elements and transition metal elements other than Co, Mn and Ni, 0.9≦p≦1.1, 0.2≦x≦0.5, 0.2≦y≦0.5, 0.1≦z≦0.4, 0≦q≦0.5, 1.9≦a≦2.1, p+x+y+z+q=2, and 0≦a≦0.02,
characterized in that when the powder is classified into small particle size-classified particles with an average particle size of 2 μm≦D 50 ≦8 μm and large particle size-classified particles with an average particle size of 10 μm≦D 50 ≦75 μm,
a ratio of % by weight of the small particle size-classified particles compared to a % by weight of the large particle size-classified particles is from 15/85 to 40/60,
a molar ratio ps of lithium to the total of nickel, cobalt, manganese and the M element contained in the small particle size-classified particles is smaller than a molar ratio pl of lithium to the total of nickel, cobalt, manganese and the M element contained in the large particle size-classified particles and wherein 0.95≦ps≦1.04, 1.03≦pl≦1.12, 0.85<ps/pl<1.
2. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the specific surface area of the lithium/nickel/cobalt/manganese-containing composite oxide powder is from 0.2 to 1.0 m 2 /g, the specific surface area of the small particle size-classified particles is from 0.5 to 2.0 m 2 /g, and the specific surface area of the large particle size-classified particles is from 0.1 to 0.5 m 2 /g.
3. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein M is at least one element selected from the group consisting of Al, Zr, Ti, Hf, Nb, Ta, Mg, Ge, Sn and Zn.
4. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the amount of free alkalis is at most 0.40 mol %.
5. A positive electrode for a lithium secondary battery comprising a cathode active material, a binder and an electroconductive material, wherein the cathode active material comprises the lithium/nickel/cobalt/manganese-containing composite oxide powder as defined in claim 1 .
6. A lithium secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte and an electrolytic solution, wherein the positive electrode is the one as defined in claim 5 .
7. A lithium/nickel/cobalt/manganese composite oxide powder having the formula Li p Ni x Co y Mn z M q O 2-a F a , wherein M is at least one element selected from the group consisting of Al, Ge, Sn, an alkaline earth metal element and a transition metal element other than Co, Mn and Ni,
wherein 0.9≦p≦1.1, 0.2≦x≦0.5, 0.2≦y≦0.5, 0.1≦z≦0.4, 0≦q≦0.05, 1.9≦2-a≦2.1, p+x+y+z+q=2,and 0≦a≦0.02,
wherein the composite oxide powder comprises a small particle size particle having an average particle size of 2 μm≦D 50 ≦8 μm and a large particle size particle having an average particle size of 10 μm≦D 50 ≦25 μm,
wherein the weight percent ratio of the small particle size particle to the large particle size particle is from 15/85 to 40/60, and
wherein the molar ratio of Li to the total molar amount of Ni, Co, Mn and the M element in the small size particle is less than the molar ratio of Li to the total molar amount of Ni, Co, Mn and the M element in the large particle.
8. The lithium/nickel/cobalt/manganese composite oxide powder according to claim 7 , wherein, a molar ratio ps of lithium to the total of nickel, cobalt, manganese and the M element contained in the small particle size-classified particles is smaller than a molar ratio pl of lithium to the total of nickel, cobalt, manganese and the M element contained in the large particle size-classified particles wherein 0.95≦ps≦1.04, 1.03≦pl≦1.12, 0.85<ps/pl<1.
9. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the specific surface area of the lithium/nickel/cobalt/manganese-containing composite oxide powder is from 0.2 to 1.0 m 2 /g, the specific surface area of the small particle size-classified particles is from 0.5 to 2.0 m 2 /g, and the specific surface area of the large particle size-classified particles is from 0.1 to 0.5 m 2 /g.
10. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein M is at least one element selected from the group consisting of Al, Zr, Ti, Hf, Nb, Ta, Mg, Ge, Sn and Zn.
11. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the amount of free alkalis is at most 0.40 mol %.
12. A positive electrode for a lithium secondary battery comprising a cathode active material, a binder and an electroconductive material, wherein the cathode active material comprises the lithium/nickel/cobalt/manganese-containing composite oxide powder as defined in claim 7 .
13. A lithium secondary battery comprising a positive electrode, a negative electrode, a non-aqueous electrolyte and an electrolytic solution, wherein the positive electrode is the one as defined in claim 12 .
14. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the small particle size-classified particles have an average particle size of 3.1 μm≦D 50 ≦8 μm.
15. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the small particle size-classified particles have an average particle size of 3.5 μm≦D 50 ≦8 μm.
16. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the small particle size-classified particles have an average particle size of 4 μm≦D 50 ≦8 μm.
17. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 1 , wherein the small particle size-classified particles and the large particle size-classified particles comprise the same elements.
18. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the small particle size-classified particles have an average particle size of 3.1 μm≦D 50 ≦8 μm.
19. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the small particle size-classified particles have an average particle size of 3.5 μm≦D 50 ≦8 μm.
20. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the small particle size-classified particles have an average particle size of 4 μm≦D 50 ≦8 μm.
21. The lithium/nickel/cobalt/manganese-containing composite oxide powder according to claim 7 , wherein the small particle size-classified particles and the large particle size-classified particles comprise the same elements.