CATHODE ACTIVE MATERIAL, METHOD FOR PREPARING SAME, AND LITHIUM SECONDARY BATTERY COMPRISING SAME

1 . A positive electrode active material for a lithium rechargeable battery, the material comprising:

a lithium metal oxide particle of a nickel-based layered structure; and

a coating layer disposed on a surface of the lithium metal oxide particle,

wherein the coating layer includes:

manganese (Mn), a manganese (Mn) compound, or a combination thereof; and

boron (B), a boron (B) compound, or a combination thereof.

2 . The positive electrode active material of claim 1 ,

wherein the coating layer includes

a mixture of a spinel phase and a rock salt phase.

3 . The positive electrode active material of claim 2 , wherein

the spinel phase and the rock salt phase

are derived from the manganese (Mn) compound.

4 . The positive electrode active material of claim 3 , wherein

the manganese (Mn) compound includes

a lithium manganese oxide, a derivative thereof, a mixture thereof, or a combination thereof.

5 . The positive electrode active material of claim 2 ,

wherein the coating layer

further includes a vitreous hyaline amorphous phase,

including a mixture of the spinel phase and the rock salt phase,

wherein the vitreous hyaline amorphous phase is derived from the boron (B) compound.

6 . (canceled)

7 . The positive electrode active material of claim 5 , wherein

the boron (B) compound includes

a lithium borate, a derivative thereof, a mixture thereof, or a combination thereof.

8 . The positive electrode active material of claim 1 , wherein

a weight ratio of [manganese (Mn), a manganese (Mn) compound, or a combination thereof] to [boron (B), a boron (B) compound, or a combination thereof] in the coating layer is in a range of 1:1 to 1:10.

9 . The positive electrode active material of claim 1 , wherein

in a total amount of the positive electrode active material (100 wt %),

the lithium metal oxide particle is contained in an amount of 0.01 to 2 wt %, and the coating layer is included as a balance.

10 . The positive electrode active material of claim 1 , wherein

the nickel-based lithium metal oxide particle

has a concentration gradient of nickel,

wherein the concentration gradient of nickel has a form in which the concentration decreases from a center of the particle in a surface direction.

11 . (canceled)

12 . The positive electrode active material of claim 9 , wherein

the concentration gradient of nickel

exists from 50 to 95% by length of a particle radius from the center of the particle.

13 . The positive electrode active material of claim 12 , wherein

the concentration gradient of nickel

has a form in which the concentration is decreased from the center of the particle in the surface direction until the particle has 40 mol % at 90% by length of the particle radius when the nickel concentration at the center of the particle is taken as 100 mol %.

14 . The positive electrode active material of claim 13 , wherein

the nickel-based lithium metal oxide particle

has an average composition across the particle represented by Chemical Formula 1:

Li 1+m [Ni 1-w1-x1-y1-z1 Co w1 M1 x1 M2 y1 M3 z1 ] 1+n O 2-p1 X p1   [Chemical Formula 1]

wherein, in Chemical Formula 1,

M 1 indicates any one element selected from a group consisting of Mn and Al,

each of M 2 and M 3 indicates an element selected from a group consisting of Mg, Sn, Ca, Ge, and Ga,

X is one element selected from the group consisting of F, N, and P, and

each of w 1 , x 1 , y 1 , z 1 , and p 1 satisfies a following corresponding inequality: 0<w 1 ≤0.2, 0≤x 1 ≤0.1, 0≤y 1 ≤0.1, 0≤z 1 ≤0.1, 0<w 1 +x 1 +y 1 +z 1 ≤0.4, and 0≤p 1 ≤0.1,

m may satisfy an inequality: −0.05≤m≤0.25, and

n may satisfy an inequality: −0.05≤n≤0.25.

15 . A preparation method of a positive electrode active material for a lithium rechargeable battery, the method comprising

performing a heat treatment on a mixture of lithium metal oxide particles having a nickel-based layered structure, a Mn-supply material, and a B-supply material,

wherein the heat treatment is performed in a temperature range of 150 to 400° C.

16 . (canceled)

17 . The preparation method of claim 15 , wherein

the heat treatment includes:

heating at a temperature rise rate of 2 to 10° C./min until the temperature reaches the temperature range of 150 to 400° C.; and

performing the heat treatment while maintaining the reached temperature range.

18 . The preparation method of claim 17 , wherein

the performing of the heat treatment while maintaining the reached temperature range

is performed for 2 to 10 hours.

19 . The preparation method of claim 15 , wherein

the mixture

contains 0.01 to 1 parts by weight of the Mn-supply material and 0.01 to 2 parts by weight of the B-supply material for 100 parts by weight of the lithium metal oxide particle.

20 . The preparation method of claim 15 , further comprising

preparing the lithium metal oxide particles before the performing of the heat treatment on the mixture.

21 . The preparation method of claim 20 , wherein

the preparation of the lithium metal oxide particle

is done by a co-precipitation method.

22 . The preparation method of claim 21 , wherein

in the preparation of the lithium metal oxide particle,

particles with a concentration gradient of nickel are prepared by using an aqueous solution of two kinds of metal salts having different molar concentrations of nickel.

23 . A lithium rechargeable battery, comprising:

a positive electrode;

a negative electrode; and

an electrolyte,

wherein the positive electrode includes the positive electrode active material for a lithium rechargeable battery according to claim 1 .