Positive electrode active material for lithium secondary battery, preparing method thereof, and lithium secondary battery including positive electrode including the same

Patent metadata

Field	Value
Publication number	US-2017133668-A1
Application number	US-201615343309-A
Country	US
Kind code	A1
Filing date	Nov 4, 2016
Priority date	Nov 6, 2015
Publication date	May 11, 2017
Grant date	—

Abstract

A positive electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery, the positive electrode active material including nickel, cobalt, and manganese, wherein the positive electrode active material has a core part and a surface part, an amount of manganese in the core part and the surface part is higher than 25 mol %, and amounts of nickel and cobalt in the positive electrode active material vary such that a concentration gradient of the nickel and the cobalt in a direction from the core part to the surface part is present in the positive electrode active material.

First claim

What is claimed is:

1 . A positive electrode active material for a lithium secondary battery, the positive electrode active material comprising nickel, cobalt, and manganese,
wherein: the positive electrode active material has a core part and a surface part, an amount of manganese in the core part and the surface part is higher than 25 mol %, and amounts of nickel and cobalt in the positive electrode active material vary such that a concentration gradient of the nickel and the cobalt in a direction from the core part to the surface part is present in the positive electrode active material.

2 . The positive electrode active material as claimed in claim 1 , wherein the amount of cobalt increases in a direction from the core part to the surface part.

3 . The positive electrode active material as claimed in claim 1 , wherein the amount of nickel decreases in a direction from the core part to the surface part.

4 . The positive electrode active material as claimed in claim 1 , wherein:
the amount of nickel in the core part is about 50 mol % or higher, and the amount of nickel in the surface part is in a range of about 30 mol % to about 40 mol %.

5 . The positive electrode active material as claimed in claim 1 , wherein:
the amount of cobalt in the core part is about 15 mol % or higher, and the amount of cobalt in the surface part is in a range of about 30 mol % to about 40 mol %.

6 . The positive electrode active material as claimed in claim 1 , wherein the positive electrode active material is a compound represented by Formula 1:
LiNi x Co y Mn z O 2   [Formula 1]
wherein, in Formula 1, 0.40≦x≦0.70, 0.05≦y≦0.35, and 0.25<z≦0.40.

7 . The positive electrode active material as claimed in claim 1 , wherein the positive electrode active material has no boundary between the core part and the surface part.

8 . The positive electrode active material as claimed in claim 1 , wherein a composition of the positive electrode active material at the core part thereof continuously changes to a different composition at the surface part thereof.

9 . The positive electrode active material as claimed in claim 1 , wherein, in the positive electrode active material,
the amount of nickel in the core part is in a range of about 50 mol % to about 55 mol %, the amount of nickel in the surface part is in a range of about 35 mol % to about 45 mol %, and the amount of nickel gradually decreases from the core part to the surface part; the amount of manganese in the core part and the surface part is in a range of about 26 mol % to about 32 mol %; and the amount of cobalt in the core part is in a range of about 15 mol % to about 25 mol %, the amount of cobalt in the surface part is in a range of about 30 mol % to about 35 mol %, and the amount of cobalt gradually increases from the core part to the surface part.

10 . A method of preparing the positive electrode active material for a lithium secondary battery as claimed in claim 1 , the method comprising:
mixing a positive electrode active material precursor represented by Formula 2 with a cobalt precursor, and primary heat-treating the mixture to prepare a positive electrode active material precursor having a functional gradient layer; and mixing the positive electrode active material precursor having a functional gradient layer with a lithium precursor, and secondary heat-treating the resultant to prepare the positive electrode active material:
Ni x Co y Mn z OH  [Formula 2]

wherein, in Formula 2, 0.40≦x≦0.70, 0.05≦y≦0.35, and 0.25<z≦0.40.

11 . The method as claimed in claim 10 , wherein an amount of the cobalt precursor is in a range of about 1 part to about 5 parts by weight, based on 100 parts by weight of the positive electrode active material precursor represented by Formula 2 and the cobalt precursor.

12 . The method as claimed in claim 10 , wherein the primary heat-treating is performed at a temperature in a range of about 450° C. to about 800° C.

13 . A lithium secondary battery comprising an active material, the active material including nickel, cobalt, and manganese,
wherein: the positive electrode active material has a core part and a surface part, an amount of manganese in the core part and the surface part is higher than 25 mol %, and amounts of nickel and cobalt in the positive electrode active material vary such that a concentration gradient of the nickel and the cobalt in a direction from the core part to the surface part is present in the positive electrode active material.

14 . The lithium secondary battery as claimed in claim 13 , wherein the amount of cobalt increases in a direction from the core part to the surface part.

15 . The lithium secondary battery as claimed in claim 13 , wherein the amount of nickel decreases in a direction from the core part to the surface part.

16 . The lithium secondary battery as claimed in claim 13 , wherein:
the amount of nickel in the core part is about 50 mol % or higher, and the amount of nickel in the surface part is in a range of about 30 mol % to about 40 mol %.

17 . The lithium secondary battery as claimed in claim 13 , wherein:
the amount of cobalt in the core part is about 15 mol % or higher, and the amount of cobalt in the surface part is in a range of about 30 mol % to about 40 mol %.

18 . The lithium secondary battery as claimed in claim 13 , wherein the positive electrode active material is a compound represented by Formula 1:
LiNi x Co y Mn z O 2   [Formula 1]
wherein, in Formula 1, 0.40≦x≦0.70, 0.05≦y≦0.35, and 0.25<z≦0.40.

19 . The lithium secondary battery as claimed in claim 13 , wherein the positive electrode active material has no boundary between the core part and the surface part.

20 . The lithium secondary battery as claimed in claim 13 , wherein, in the positive electrode active material,
the amount of nickel in the core part is in a range of about 50 mol % to about 55 mol %, the amount of nickel in the surface part is in a range of about 35 mol % to about 45 mol %, and the amount of nickel gradually decreases from the core part to the surface part; the amount of manganese in the core part and the surface part is in a range of about 26 mol % to about 32 mol %; and the amount of cobalt in the core part is in a range of about 15 mol % to about 25 mol %, the amount of cobalt in the surface part is in a range of about 30 mol % to about 35 mol %, and the amount of cobalt gradually increases from the core part to the surface part.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Kim Jinhwa
• Moon Joongho
• Choi Jeonjin
• Song Yumi
• Kim Minhan
• Park Dohyung
• Kwon Seonyoung

Classifications

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/364 Primary

  as mixtures · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · 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