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

Patent metadata

Field	Value
Publication number	US-2019027739-A1
Application number	US-201816044399-A
Country	US
Kind code	A1
Filing date	Jul 24, 2018
Priority date	Jul 24, 2017
Publication date	Jan 24, 2019
Grant date	—

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, wherein the functional layer has one kind of a crystal structure different from a crystal structure of the core, and wherein the positive active material comprises 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.

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 an average thickness of the functional layer is about 3 nm to about 60 nm.

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

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

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

7 . The positive active material of claim 1 , wherein the functional layer comprises a first layer having at least two kinds of crystal structure and a second layer having the crystal structure different from the crystal structure of the core.

8 . The positive active material of claim 7 , wherein an average thickness of the first layer is 2% to 20% of a total average thickness of the functional layer.

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

10 . The positive active material of claim 7 , wherein the first layer has a mixed structure of a cubic crystal structure and a hexagonal crystal structure, and
the second layer has a cubic crystal structure.

11 . The positive active material of claim 1 , wherein in Chemical Formula 1, x satisfies Equation 1:
0.7≤ x ≤0.93.  Equation 1

12 . 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.

13 . The positive active material of claim 7 , wherein the first layer has at least two kinds of crystal structure and the second layer has only the crystal structure different from the crystal structure of the core.

14 . The positive active material of claim 7 , wherein the first layer has at least two kinds of crystal structure and the second layer has the crystal structure different from the crystal structure of the core, and
wherein the crystal structure different from the crystal structure of the core is present in the second layer as a major component.

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

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/628

  Inhibitors, e.g. gassing inhibitors, corrosion inhibitors · CPC title

• C01P2006/80

  Compositional purity · CPC title