Method of producing cobalt-coated precursor, cobalt-coated precursor produced thereby, and positive electrode active material prepared using same

Patent metadata

Field	Value
Publication number	US-11031593-B2
Application number	US-201716068303-A
Country	US
Kind code	B2
Filing date	Jan 2, 2017
Priority date	Jan 5, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

The present invention relates to a method of producing a cobalt-coated precursor, the cobalt-coated precursor produced by the method and a positive electrode active material for a lithium secondary battery, the positive electrode active material which is prepared using the cobalt-coated precursor and, more particularly, to a method of preparing a new positive electrode active material having improved high capacity and stability by coating cobalt on the surface of a precursor in the precursor step, thereby improving characteristics of the precursor degraded when washed with water, and a positive electrode active material prepared by the method.

First claim

What is claimed is:

1. A method of producing positive active material for a lithium secondary battery comprising the following steps:
a step 1 of mixing a metal mixed solution including a nickel-containing compound, a first cobalt-containing compound, an aqueous ammonia solution as a complexing agent, and a hydroxyl group-providing aqueous alkaline solution as a pH adjusting agent to prepare materials including a nickel-cobalt composite hydroxide represented by the following chemical formula 1 by a co-precipitation method;
[Ni x Co y M z ](OH) 2   [Chemical Formula 1]

(In chemical formula 1, 0.6≤x<1.00, 0≤y≤0.20, 0≤z≤0.2, x+y+z=1, and
M is one or more selected from the group consisting of Al, Mn, B, Ba, Cr, F, Li, Mo, P, Sr, Ti and Zr)
a step 2 of preparing cobalt sulfate or cobalt nitrate as a second cobalt-containing compound;
a step 3 of injecting the materials including the nickel-cobalt composite hydroxide prepared in the step 1 into an aqueous alkaline solution or distilled water, and mixing the cobalt sulfate or the cobalt nitrate containing compound prepared in the step 2 with the materials including the nickel-cobalt composite hydroxide injected into the aqueous alkaline solution or distilled water to obtain cobalt-coated materials;
a step 4 of separating the cobalt-coated materials;
a step 5 of drying the separated cobalt-coated materials to prepare a cobalt-coated precursor;
a step 6 of mixing the prepared cobalt-coated precursor with a lithium compound to obtain a mixture; and
a step 7 of heat-treating the mixture to obtain a lithium metal composite oxide.

2. The method of claim 1 , further comprising a step 1-1 of separating the nickel-cobalt composite hydroxide from the materials including the nickel-cobalt composite hydroxide prepared in the step 1 and cleaning the separated nickel-cobalt composite hydroxide to prepare a nickel-cobalt composite hydroxide in the form of powder.

3. The method of claim 1 , wherein the first cobalt-containing compound and the second cobalt-containing compound are the same compound.

4. The method of claim 1 , wherein the cobalt is coated on the precursor in an amount of 0.1 to 15 mol %.

5. The method of claim 1 , wherein the step 5 of performing a drying process comprises performing the drying process at a drying temperature of 80 to 200° C. for a drying time of 5 to 20 hours.

6. The method of claim 1 , wherein the step 3 comprises maintaining temperature of the mixed solution to 10 to 70° C.

7. The method of claim 1 , wherein the step 7 comprises firing the mixture at 650 to 850° C. in an oxygen atmosphere.

8. The method of claim 1 , further comprising a step 8 of injecting distilled water into a reactor, constantly maintaining temperature of the distilled water, injecting the lithium metal composite oxide obtained in the step 7 into the constant temperature-maintained distilled water to stir the lithium metal composite oxide with the constant temperature-maintained distilled water.

Assignees

• Ecopro Bm Co Ltd
• Samsung Sdi Co Ltd

Inventors

• Choi Moon Ho
• Shin Jong Seung
• Yu Hyun Jong
• Jeon Suk Yong
• Oh Eun Ok
• Lee Sang Wook
• Choi Yoon Young

Classifications

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01G53/42

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

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01P2002/52

  containing elements as dopants · CPC title

• C01G53/04

  Oxides · CPC title