Active material for non-aqueous electrolyte secondary battery and manufacturing method therefore

1. An active material for a non-aqueous electrolyte secondary battery comprising a lithium-containing transition metal oxide containing nickel and manganese and having a closest-packed structure of oxygen, wherein:

an atomic ratio M Li /M T between the number of moles of lithium M Li and the number of moles of transition metal M T contained in said lithium-containing transition metal oxide is 1.1 to 1.4,

said lithium-containing transition metal oxide has a crystal structure attributed to a hexagonal system, and the X-ray diffraction image of said crystal structure has a peak P 003 attributed to the (003) plane and a peak P 104 attributed to the (104) plane,

an integrated intensity ratio I 003 /I 104 between the peak P 003 and the peak P 104 varies reversibly within a range from 0.7 to 1.5 in association with absorption and desorption of lithium by said lithium-containing transition metal oxide,

said integrated intensity ratio varies linearly and continuously, and

in said crystal structure, a lattice constant a representing a length of a axis and a lattice constant c representing a length of c axis satisfy 4.945<c/a, and c<14.30 Å.

2. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein said lithium-containing transition metal oxide is derived from an oxide containing nickel and manganese, the oxide serving as a precursor oxide.

3. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 2 , wherein said precursor oxide includes an oxide represented by R32 type NiMnO 3 .

4. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein a capacity obtained when the potential of said lithium-containing transition metal oxide varies from 2.5 V to 4.6 V versus lithium metal is 160 mAh/g or more.

5. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein the primary particles constituting said lithium-containing transition metal oxide have a mean particle size of 1 μm or less, and at least a part of said primary particles have a triangular or hexagonal face on their surfaces.

6. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 5 , wherein the shape of the primary particles is columnar.

7. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 5 , wherein the primary particles are welded or sintered to one another at part of their surfaces, thereby to form secondary particles.

8. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein at least one heteroelement selected from the group consisting of cobalt, iron, zinc, aluminum, magnesium, strontium, yttrium, and ytterbium is doped in the inside or on the surface of the primary particles or secondary particles constituting said lithium-containing transition metal oxide.

9. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 1 , wherein the number of moles of nickel M Ni and the number of moles of manganese M Mn contained in said lithium-containing transition metal oxide are substantially equal to each other, and a molar ratio M 0 represented by (M Ni +M Mn )/2 satisfies

0≦|M Ni −M 0 |/M 0 ≦0.1, and 0≦|M Mn −M 0 |/M 0 ≦0.1.

10. An active material for a non-aqueous electrolyte secondary battery comprising a lithium-containing transition metal oxide containing nickel and manganese and having a closest-packed structure of oxygen, wherein:

an atomic ratio M Li /M T between the number of moles of lithium M Li and the number of moles of transition metal M T contained in said lithium-containing transition metal oxide is 1.1 to 1.4,

said lithium-containing transition metal oxide has a crystal structure attributed to a hexagonal system, and the X-ray diffraction image of said crystal structure has a peak P 003 attributed to the (003) plane and a peak P 104 attributed to the (104) plane,

an integrated intensity ratio I 003 /I 104 between the peak P 003 and the peak P 104 varies reversibly within a range from 0.7 to 1.5 in association with absorption and desorption of lithium by said lithium-containing transition metal oxide,

when said lithium-containing transition metal oxide desorbs lithium until its potential versus lithium metal reaches 5 V, the oxygen array in said crystal structure undergoes substantially no change, and

in said crystal structure, a lattice constant a representing a length of a axis and a lattice constant c representing a length of c axis satisfy 4.945<c/a, and c<14.30 Å.

11. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 10 , wherein in the process of desorbing lithium until the potential of said lithium-containing transition metal oxide reaches 5 V versus lithium metal, substantially no irreversible capacity involving Li 2 O production is generated.

12. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 10 , wherein the potential of said lithium-containing transition metal oxide versus lithium metal varies continuously within a range from 4.5 V to 4.6 V.

13. The active material for a non-aqueous electrolyte secondary battery in accordance with claim 10 , wherein the X-ray diffraction image of said crystal structure has a peak P 110 attributed to the (110) plane, and the profile of the peak P 110 becomes broader as said atomic ratio M Li /M T is increased.

14. A non-aqueous electrolyte secondary battery comprising a positive electrode including the active material in accordance with claim 1 , a negative electrode, a separator interposed between said positive electrode and said negative electrode, and a non-aqueous electrolyte.