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

Patent metadata

Field	Value
Publication number	US-9660291-B2
Application number	US-201213569386-A
Country	US
Kind code	B2
Filing date	Aug 8, 2012
Priority date	Dec 7, 2011
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A positive active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including the positive active material. The positive active material includes a core part and a shell part that include a nickel-based composite oxide, and a content of nickel in the core part is larger than that in the shell part.

First claim

What is claimed is:

1. A positive active material for a lithium secondary battery, the positive active material comprising:
a core part comprising LiNi 0.6 Co 0.2 Mn 0.2 O 2 and a shell part comprising LiNi 0.33 Co 0.33 Mn 0.33 O 2 having a porous structure including a plurality of pores;
wherein
the core part comprises needle-like particles; and
the shell part permeates into the open pores of the core part and fills the pores.

2. The positive active material of claim 1 , wherein the core part or a core part precursor has a curved surface structure.

3. The positive active material of claim 1 , wherein an amount of the core part is in a range of about 40 to about 90 parts by weight based on 100 parts by weight of the positive active material, and an amount of the shell part is in a range of about 10 to about 60 parts by weight based on 100 parts by weight of the positive active material.

4. The positive active material of claim 1 , wherein a diameter of the core part is in a range of about 1 to about 10 μm, and a diameter of the shell part is in a range of about 5 to about 10 μm.

5. A method of preparing a positive active material of claim 1 for a lithium secondary battery, the method comprising:
a first process for mixing a first precursor solution comprising a nickel salt, a cobalt salt, and a manganese salt and a base to prepare a first mixture and inducing a reaction in the first mixture to obtain a precipitate;
a second process for adding to the precipitate a second precursor solution comprising a nickel salt, a cobalt salt, and a manganese salt and a base to obtain a second mixture and inducing a reaction in the second mixture to obtain a composite metal hydroxide; and
mixing the composite metal hydroxide with a lithium salt and heat treating the mixed composite metal hydroxide to prepare the positive active material according to claim 1 ,
wherein a content of nickel in the first precursor solution is adjusted to be larger than that in the second precursor solution.

6. The method of claim 5 , wherein a reaction time of the second mixture in the second process is adjusted to be longer than that of the first mixture in the first process.

7. The method of claim 5 , wherein a reaction time of the first mixture in the first process is in a range of about 5 to about 7 hours, and a reaction time of the second mixture in the second process is in a range of about 8 to about 10 hours.

8. The method of claim 5 , wherein an amount of the nickel salt in the first process is in a range of about 1 to about 1.2 moles based on 1 mole of the cobalt salt.

9. The method of claim 5 , wherein a pH of the first mixture in the first process is adjusted to be in a range of about 10 to about 11, and a pH of the second mixture in the second process is adjusted to be in a range of about 11.5 to about 12.0.

10. A lithium secondary battery comprising the positive active material according to claim 1 .

Assignees

• Kim Min-Han
• Park Do-Hyung
• Kim Ji-Hyun
• Lee Jeong-Seop
• Kim Chang-Hyuk
• Kwon Seon-Young
• Kim Yoon-Chang
• Samsung Sdi Co Ltd

Inventors

• Kim Min-Han
• Park Do-Hyung
• Kim Ji-Hyun
• Lee Jeong-Seop
• Kim Chang-Hyuk
• Kwon Seon-Young
• Kim Yoon-Chang

Classifications

• H01M4/366

  as layered products · CPC title

• C01P2002/88

  by thermal analysis data, e.g. TGA, DTA, DSC · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M4/0497

  Chemical precipitation · CPC title

• H01M10/0525 Primary

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