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-2019020026-A1
Application number	US-201716068303-A
Country	US
Kind code	A1
Filing date	Jan 2, 2017
Priority date	Jan 5, 2016
Publication date	Jan 17, 2019
Grant date	—

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

1 . A method of producing a cobalt-coated precursor is provided. The method comprises:
a step 1 of mixing a metal mixed solution including a nickel-containing compound, a first cobalt-containing compound, a manganese-containing compound and a metal M, an aqueous ammonia solution as a complexing agent, and a hydroxyl group-providing aqueous alkaline solution as a pH adjusting agent to prepare a solution 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 a cobalt coating solution including a second cobalt-containing compound; a step 3 of injecting the solution including the nickel-cobalt composite hydroxide prepared in the step 1 into an aqueous alkaline solution or distilled water, and mixing the cobalt coating solution prepared in the step 2 with the solution including the nickel-cobalt composite hydroxide injected into the aqueous alkaline solution or distilled water to obtain a mixed solution, thereby coating a precursor with the mixed solution to coat cobalt on the precursor; a step 4 of separating a cobalt-coated precursor; and a step 5 of drying the separated cobalt-coated precursor.

2 . The method of claim 1 , further comprising a step 1-1 of separating the nickel-cobalt composite hydroxide from the solution 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 cobalt sulfate or cobalt nitrate.

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

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

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 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.

8 . A cobalt-coated precursor produced by the method of claim 1 .

9 . A method of preparing a positive electrode active material for a lithium secondary battery, the method comprising:
a step 6 of mixing the cobalt-coated precursor according to claim 8 with a lithium compound to obtain a mixture; and a step 7 of heat-treating the mixture to obtain a lithium metal composite oxide.

10 . The method of claim 9 , wherein the step 7 comprises firing the mixture at 650 to 850° C. in an oxygen atmosphere.

11 . The method of claim 9 , 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.

12 . A positive electrode active material for a lithium secondary battery, the positive electrode active material prepared by the method of claim 8 .

13 . The positive electrode active material for the lithium secondary battery of claim 12 , comprising 0.15 wt % or less of a residual lithium.

14 . The positive electrode active material for the lithium secondary battery of claim 12 , having a 2θ value at XRD exhibiting a corresponding peak of LiCoO 2 in a range of 45° to 46°, 18° to 19° or 37° to 38°.

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

• C01G51/42

  containing alkali metals, e.g. LiCoO2 · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M4/525 Primary

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

• H01M10/052

  Li-accumulators · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title