Positive active material for rechargeable lithium battery and rechargeable lithium battery including same

Patent metadata

Field	Value
Publication number	US-12548765-B2
Application number	US-201816044399-A
Country	US
Kind code	B2
Filing date	Jul 24, 2018
Priority date	Jul 24, 2017
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

A positive active material for a rechargeable lithium battery includes a core including a compound represented by Chemical Formula 1 and a functional layer on a surface of the core. The functional layer has one kind of a crystal structure that is different from the crystal structure of the core. The positive active material includes about 100 ppm to about 400 ppm of sulfur:

Li a Ni x Co y Me z O 2 ,  Chemical Formula 1

wherein in Chemical Formula 1, 0.9≤a≤1.1, 0.5≤x≤0.93, 0<y≤0.3, 0<z≤0.3, x+y+z=1, and Me is Mn or Al.

First claim

What is claimed is:

1 . A positive active material for a rechargeable lithium battery, the positive active material comprising:
a core comprising a compound represented by Chemical Formula 1; and a functional layer on a surface of the core, an average thickness of the functional layer being about 3 nm to about 60 nm, wherein the positive active material comprises about 100 ppm to about 400 ppm of sulfur, wherein a portion of the functional layer directly on the core consists of a same compound as the compound represented by Chemical Formula 1 comprised in the core, and the same compound in the portion of the functional layer is of a first crystal structure different from a second crystal structure of the compound comprised in the core, wherein the functional layer comprises a first layer having a mixed structure of a cubic crystal structure and a hexagonal crystal structure, and a second layer having a cubic crystal structure different from the second crystal structure of the core, and wherein in the cubic crystal structure different from the second crystal structure of the core, an angle between a (−111) plane and a (−11-1) plane is about 70 degrees:
Li a Ni x Co y Me z O 2 ,  Chemical Formula 1

in Chemical Formula 1, 0.9≤a≤1.1, 0.85≤x≤0.93, 0<y≤0.3, 0<z≤0.3, x+y+z=1, and Me is Al.

2 . The positive active material of claim 1 , wherein the positive active material comprises about 100 ppm to about 200 ppm of sulfur.

3 . The positive active material of claim 1 , wherein the functional layer comprises a layer that has only the first crystal structure different from the second crystal structure of the core.

4 . The positive active material of claim 1 , wherein the first crystal structure of the functional layer is a cubic structure.

5 . The positive active material of claim 1 , wherein the second crystal structure of the core is a hexagonal structure or a layered hexagonal structure.

6 . The positive active material of claim 1 , wherein an average thickness of the first layer is 2% to 20% of a total average thickness of the functional layer.

7 . The positive active material of claim 1 , wherein the first layer is on the surface of the core, and
the second layer is on the surface of the first layer.

8 . A rechargeable lithium battery comprising:
a positive electrode comprising the positive active material of claim 1 ; a negative electrode comprising a negative active material; and an electrolyte.

9 . The positive active material of claim 1 , wherein the second layer has only the cubic crystal structure different from the second crystal structure of the core.

10 . The positive active material of claim 1 , wherein the second layer has the cubic crystal structure different from the second crystal structure of the core, and
wherein the cubic crystal structure different from the second crystal structure of the core is present in the second layer as a major component.

11 . A positive active material for a rechargeable lithium battery, the positive active material comprising:
a core comprising a compound represented by Chemical Formula 1; and a functional layer on a surface of the core, an average thickness of the functional layer being about 3 nm to about 60 nm, wherein the positive active material comprises about 100 ppm to about 400 ppm of sulfur, wherein a portion of the functional layer directly on the core consists of a same compound as the compound represented by Chemical Formula 1 comprised in the core, and the same compound in the portion of the functional layer is of a first crystal structure different from a second crystal structure of the compound comprised in the core, wherein the functional layer comprises a first layer having a mixed structure of a cubic crystal structure and a hexagonal crystal structure, and a second layer having a cubic crystal structure different from the second crystal structure of the core, and wherein in the cubic crystal structure different from the second crystal structure of the core, an angle between a (−111) plane and a (−11-1) plane is about 70 degrees:
Li a Ni x Co y Me z O 2 ,  Chemical Formula 1

in Chemical Formula 1, 0.9≤a≤1.1, 0.85≤x≤0.93, 0<y≤0.3, 0<z≤0.3, x+y+z=1, and Me is Mn or Al.

12 . The positive active material of claim 1 , wherein the second layer comprises a mixed structure of the cubic crystal structure and a hexagonal crystal structure, the cubic crystal structure being more prevalent than the hexagonal structure.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Kim Minhan
• Kim Dongjin
• Kim Ilseok
• Park Dohyung
• Park Junseok
• Lee Daehoe
• Lim Okgyu
• Jeon Gyuran
• Choi Jeonjin

Classifications

• C01G53/42

  containing alkali metals, e.g. LiNiO2 · CPC title

• C01P2006/80

  Compositional purity · CPC title

• C01G53/50

  of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M2004/028

  Positive electrodes · CPC title