# US 12,763,320 B2 · Composite positive active material for lithium secondary battery, method of preparing composite positive active material, and lithium secondary battery including composite positive active material

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- Number: US 12,763,320 B2
- Document ID: US12763320B2
- Status: Granted
- Kind: B2
- Application number: 18/053,125
- Filed: 2022-11-07
- Published: 2023-05-11
- Granted: 2026-10-13
- Earliest claimed: 2021-11-08
- Assignees: Samsung SDI Co., Ltd.
- Applicants: Samsung SDI Co., Ltd.
- Inventors: Youngki Kim; Yongmok Cho; Sungho Choo; Sangmi Kim; Minjae Choi; Jaeyoung Jeong; Hyunjei Chung
- Web page: https://patentgrep.com/patent/US12763320B2

## CPC

- H01M 4/366: {as layered products}
- H01M 4/525: of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
- H01M 2004/028: {Positive electrodes}
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY

## Abstract

Provided are a composite positive active material for a lithium secondary battery, a method of preparing the composite positive active material, and a lithium secondary battery containing a positive electrode including the composite positive active material. The composite positive active material may include a lithium cobalt-based oxide, wherein a particle coating portion may be in an island form on a surface of the lithium cobalt-based oxide, the particle coating portion including a first coating layer containing lithium titanium-based oxide, a lithium-deficient cobalt oxide phase having a molar ratio of lithium to cobalt of 0.9 or less may be included in an inner portion of the lithium cobalt-based oxide corresponding to the particle coating portion, and the composite positive active material may include a first lithium zirconium-based oxide spaced apart from a surface of the lithium cobalt-based oxide.

## Claims

### Claim 1

A composite positive active material for a lithium secondary battery, comprising a lithium cobalt-based oxide, wherein:
a particle coating portion is in an island form on a surface of the lithium cobalt-based oxide, the particle coating portion comprising a first coating layer comprising a lithium titanium-based oxide,
a lithium-deficient cobalt oxide phase having a molar ratio of lithium to cobalt of 0.9 or less is comprised in an inner portion of the lithium cobalt-based oxide corresponding to the particle coating portion, and
the composite positive active material comprises a first lithium zirconium-based oxide spaced apart from a surface of the lithium cobalt-based oxide toward a center of the lithium cobalt-based oxide,
wherein the lithium cobalt-based oxide includes aluminum and magnesium, and a content of aluminum in the lithium cobalt-based oxide is 4,000 ppm or greater, and a content of magnesium in the lithium cobalt-based oxide is 1,000 ppm or greater, wherein the lithium-deficient cobalt oxide phase comprises a compound represented by Formula 5, a compound represented by Formula 5-1, or a compound represented by Formula 5-2, and wherein the particle coating portion further comprises a second coating layer, and the second coating layer is on the first coating layer and comprises a second lithium zirconium-based oxide:
wherein, in Formula 5, M is W, Mo, Zr, Ti, Mg, Ta, Al, Fe, V, Cr, Ba, Ca, Nb, or a combination thereof, 0.1≤α≤0.5, 0<a≤0.05, and 0≤x≤0.05,
wherein, in Formula 5-1, M is W, Mo, Zr, Ti, Mg, Ta, Al, Fe, V, Cr, Ba, Ca, Nb, or a combination thereof, 0.1≤α0.5, 0<a≤0.05, and 0≤x≤0.05,
wherein, in Formula 5-2, M is W, Mo, Zr, Ti, Mg, Ta, Al, Fe, V, Cr, Ba, Ca, Nb, or a combination thereof, and 0≤x≤0.05.

### Claim 2 (depends on 1)

The composite positive active material of claim 1, wherein a content ratio of magnesium to cobalt, based on a number of moles of magnesium to a number of moles of cobalt, comprised in the lithium-deficient cobalt oxide phase is greater than a content ratio of magnesium to cobalt, based on a number of moles of magnesium to a number of moles of cobalt, comprised in the lithium cobalt-based oxide.

### Claim 3 (depends on 1)

The composite positive active material of claim 1, wherein a surface coating portion is on an inner portion of another surface of the lithium cobalt-based oxide, and the surface coating portion comprises a third coating layer having a spinel crystalline structure.

### Claim 4 (depends on 1)

The composite positive active material of claim 1, wherein a content of the second lithium zirconium-based oxide is in a range of about 0.05 parts to about 0.2 parts by weight, based on 100 parts by weight of the lithium cobalt-based oxide.

### Claim 5 (depends on 1)

The composite positive active material of claim 1, wherein the second lithium zirconium-based oxide comprises a compound represented by Formula 2:
wherein, in Formula 2, M2 is at least one element selected from the group consisting of boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), and aluminum (Al), and
−0.1≤a≤0.1, 0≤x<1, and 0≤z≤0.1.

### Claim 6 (depends on 1)

The composite positive active material of claim 1, wherein the inner portion is in contact with the particle coating portion, and
the first lithium zirconium-based oxide is present in a particle state at a position spaced apart from the inner portion.

### Claim 7 (depends on 1)

The composite positive active material of claim 1, wherein the first lithium zirconium-based oxide is present within 150 nm from a surface of the lithium cobalt-based oxide.

### Claim 8 (depends on 1)

The composite positive active material of claim 1, wherein the first lithium zirconium-based oxide has a layered crystalline structure and is represented by Formula 6:
wherein, in Formula 6, M1 is at least one element selected from the group consisting of boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), and aluminum (Al), and
−0.1≤a≤0.1, 0≤x<1, and 0≤z≤0.5.

### Claim 9 (depends on 1)

The composite positive active material of claim 1, wherein the lithium-deficient cobalt oxide phase has a spinel crystalline structure, the lithium-deficient cobalt oxide phase is present in a portion within 100 nm from an outermost surface of the lithium cobalt-based oxide.

### Claim 10 (depends on 1)

The composite positive active material of claim 1, wherein the lithium titanium-based oxide is a compound represented by Formula 1:
wherein, in Formula 1, −0.1≤a≤0.1, 0<x≤0.5, and 0<y≤0.1.

### Claim 11 (depends on 3)

The composite positive active material of claim 3, wherein the surface coating portion comprises a lithium cobalt-based oxide A.

### Claim 12 (depends on 11)

The composite positive active material of claim 11, wherein a content of the lithium cobalt-based oxide A is in a range of about 0.01 parts to about 1 part by weight, based on 100 parts by weight of the lithium cobalt-based oxide.

### Claim 13 (depends on 1)

The composite positive active material of claim 1, wherein the lithium cobalt-based oxide is a compound represented by Formula 3:
wherein, in Formula 3, 0.9≤a≤1.1, 0≤b≤0.02, 0≤x≤0.04, and 0≤y≤0.01, and
M3 is one selected from Ni, K, Na, Ca, Mg, Si, Fe, Cu, Zn, Ti, Sn, V, Ge, Ga, B, P, Se, Bi, As, Zr, Mn, Cr, Ge, Sr, Sc, Y, and a combination thereof.

### Claim 14 (depends on 1)

The composite positive active material of claim 1, wherein a content of the lithium titanium-based oxide in the particle coating portion is in a range of about 0.05 parts to about 1.0 parts by weight, based on 100 parts by weight of the lithium cobalt-based oxide.

### Claim 15 (depends on 1)

The composite positive active material of claim 1, wherein the lithium cobalt-based oxide is small particles, large particles, or a mixture of small particles and large particles.

### Claim 16 (depends on 15)

The composite positive active material of claim 15, wherein a size of the large particles is in a range of about 10 μm to about 20 μm, and a size of the small particles is in a range of about 3 μm to about 6 μm.

### Claim 17 (depends on 15)

The composite positive active material of claim 15, wherein a mixing weight ratio of large particles to small particles in the mixture of small particles and large particles is in a range of about 7:3 to about 9:1.

### Claim 18 (depends on 1)

A method of preparing the composite positive active material for a lithium secondary battery of claim 1, the method comprising: mixing a lithium cobalt-based oxide, a titanium precursor, and cobalt hydroxide together to obtain a first precursor mixture and heat-treating the first precursor mixture; and
mixing a product of the primary heat treatment together with a zirconium precursor to obtain a second precursor mixture and heat-treating the second precursor mixture.

### Claim 19 (depends on 18)

The method of claim 18, wherein a content of the zirconium precursor is in a range of about 0.6 parts to about 1.4 parts by weight, based on 100 parts by weight of the lithium cobalt-based oxide.

### Claim 20 (depends on 18)

The method of claim 18, wherein a content of the cobalt hydroxide is in a range of about 3.5 parts to about 7 parts by weight, based on 100 parts by weight of the lithium cobalt-based oxide.

### Claim 21 (depends on 18)

The method of claim 18, wherein the zirconium precursor is zirconium oxide, and the titanium precursor is at least one selected from titanium hydroxide, titanium chloride, titanium sulfate, and titanium oxide.

### Claim 22 (depends on 18)

The method of claim 18, wherein the heat-treating of the first precursor mixture is performed at a temperature in a range of about 850° C. to about 980° C.

### Claim 23 (depends on 18)

The method of claim 18, wherein the heat-treating of the second precursor mixture is performed at a temperature in a range of about 950° C. to about 1,000° C.

### Claim 24 (depends on 1)

A lithium secondary battery comprising: a positive electrode comprising the composite positive active material according to claim 1; a negative electrode; and an electrolyte between the positive electrode and the negative electrode.