Li-Ni composite oxide particles for non-aqueous electrolyte secondary battery, process for producing the same, and non-aqueous electrolyte secondary battery

1. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery, comprising a Li—Ni composite oxide whose secondary particles form core particles thereof and have a composition represented by the formula:

Li x1 Ni 1-y1-z1-w1 Co y1 Mn z1 M w1 O 2

in which 0.9≦x1≦1.3; 0.1≦y1≦0.3; 0.0≦z1≦0.3; 0.05≦w1≦0.1; and M is Al,

wherein a Li—Ni composite oxide having a composition represented by the formula:

Li x2 Ni 1-y2-z2-w2 Co y2 Mn z2 M w2 O 2

in which 0.9≦x2≦1+z2; 0≦y2≦0.33; 0≦z2≦0.5; 0≦w2≦0.1; and M is Al with the proviso that 0.5≦(1−y2−z2−w2)/(y2+z2+w2), 0.3≦(z1+z2) and 0<(z2−z1)≦0.5),

is coated or present on a surface of the respective secondary particles.

2. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a weight percentage of the Li—Ni composite oxide which is coated or present on the surface of the Li—Ni composite oxide forming the core particles is not less than 3% and not more than 20% based on the weight of the Li—Ni composite oxide forming the core particles, or a ratio of a content of Ni element in the Li—Ni composite oxide which is coated or present on the surface of the Li—Ni composite oxide forming the core particles to a content of Ni element in the Li—Ni composite oxide forming the core particles satisfies the relationship represented by the formula:

(1- y 2- z 2- w 2)/(1- y 1- z 1- w 1)≦1.

3. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery according to claim 1 , wherein when using a negative electrode formed from a metallic lithium or a material which allows a lithium ion to be intercalated and de-intercalated to the Li—Ni composite oxide forming the core particles, an exothermic maximum peak thereof observed at a temperature ranging from 200 to 290° C. in a differential thermal analysis under a 4.5 V charged condition is increased by 15° C. or more.

4. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a discharge capacity thereof as measured at a charge/discharge rate of 0.2 mA/cm 2 in the range of 4.3 to 3.0 V with respect to a negative electrode formed from a material which allows a metallic lithium or a lithium ion to be intercalated and de-intercalated to the Li—Ni composite oxide forming the core particles, is not less than 180 mAh/g.

5. A process for producing the Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery as defined in claim 1 , comprising:

allowing the Li—Ni composite oxide to be coated or present on a surface of the respective secondary particles of the Li—Ni composite oxide forming the core particles by subjecting these materials to a wet chemical treatment or a dry mechanical treatment, or further to a thermal treatment in an oxygen atmosphere at a temperature of not lower than 250° C. for 10 min or longer in addition to the wet or dry treatment.

6. A non-aqueous electrolyte secondary battery comprising a positive electrode comprising a positive electrode active material formed from the Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery as defined in claim 1 .

7. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery, comprising a Li—Ni composite oxide whose secondary particles form core particles thereof and have a composition represented by the formula:

Li x1 Ni 1-y1-z1-w1 Co y1 Mn z1 M w1 O 2-v1 K v1

in which 0.9≦x1≦1.3; 0.1≦y1≦0.3; 0.0≦z1≦0.3; 0.05≦w1<0.1; 0≦v1≦0.05; M is Al; and K is at least one anion selected from the group consisting of F − and PO 4 3− ,

wherein a Li—Ni composite oxide having a composition represented by the formula:

Li x2 Ni 1-y2-z2-w2 Co y2 Mn z2 M w2 O 2-v2 K v2

in which 0.9≦x2≦1+z2; 0≦y2≦0.33; 0≦z2≦0.5; 0≦w2≦0.1; and 0≦v2≦0.05, with the proviso that 0.5≦(1−y2−z2−w2)/(y2+z2+w2), 0.3≦(z1+z2) and 0<(z2−z1)≦0.5); M is at least one metal selected from the group consisting of Al, Fe, Mg, Zr and Ti; and K is at least one anion selected from the group consisting of F − and PO 4 3− ,

is coated or present on a surface of the respective secondary particles.

8. Li—Ni composite oxide particles for a non-aqueous electrolyte secondary battery, comprising a Li—Ni composite oxide whose secondary particles form core particles thereof and have a composition represented by the formula:

Li x1 Ni 1-y1-z1-w1 Co y1 Mn z1 M w1 O 2-v1 K v1

(in which 1.0<x1≦1.3; 0.1≦y1≦0.3; 0.0≦z1≦0.3; 0≦w1<0.1; 0<v1≦0.05; M is at least one metal selected from the group consisting of Al and Fe; and K is at least one anion selected from the group consisting of F − and PO 4 3− ),

wherein a Li—Ni composite oxide having a metal mol number of (x1−1) and a composition represented by the formula:

Li x2 Ni 1-y2-z2-w2 Co y2 Mn z2 M w2 O 2-v2 K v2

in which 0≦y2≦0.33; 0≦z2≦0.5; 0≦w2≦0.1; and 0≦v2≦0.05, with the proviso that 0.5≦(1−y2−z2−w2)/(y2+z2+w2), 0.3≦(z1+z2) and 0<(z2−z1)≦0.5; M is A; and K is at least one anion selected from the group consisting of F − and PO 4 3− ,

is coated or present on a surface of the respective secondary particles.