Positive active material, positive electrode, and lithium battery including the same and method of manufacture thereof

Patent metadata

Field	Value
Publication number	US-2015243970-A1
Application number	US-201514598175-A
Country	US
Kind code	A1
Filing date	Jan 15, 2015
Priority date	Feb 27, 2014
Publication date	Aug 27, 2015
Grant date	—

Abstract

A positive active material, a method of preparing the positive active material, a positive electrode including the positive active material, and a lithium battery including the positive active material are disclosed. The positive active material includes a core and a coating layer on the core. The coating layer includes a sulfur component. When a binding energy peak of the sulfur is measured by X-ray photoelectron spectroscopy (XPS), the binding energy peak is observed at about 165 eV to about 168 eV, and the stability of the positive active material may be improved due to the coating layer. Accordingly, the lifespan properties of a lithium battery including the positive active material may be improved.

First claim

What is claimed is:

1 . A positive active material comprising:
a core; and a coating layer on the core, and comprising a sulfur (S) component, wherein when measured by X-ray photoelectron spectroscopy (XPS), a binding energy peak of the sulfur is observed at about 165 eV to about 168 eV.

2 . The positive active material according to claim 1 , wherein the core comprises a lithium nickel composite oxide.

3 . The positive active material according to claim 2 , wherein an amount of nickel is at least 60 mole % based on a total number of moles of metal atoms except for lithium in the lithium nickel composite oxide.

4 . The positive active material according to claim 1 , wherein the core comprises a lithium nickel composite oxide represented by Formula 1:
Li a (Ni x M y ′M z ″)O 2   Formula 1
wherein, M′ is at least one element selected from the group consisting of Co, Mn, Ni, Al, Mg, and Ti; and M″ is at least one element selected from the group consisting of Ca, Mg, Al, Ti, Sr, Fe, Co, Mn, Ni, Cu, Zn, Y, Zr, Nb, and B, 0.8<a≦1.2, 0.6≦x≦1, 0≦y≦0.4, 0≦z≦0.4, and x+y+z≦1.2.

5 . The positive active material according to claim 4 , wherein the core comprises a lithium nickel composite oxide represented by Formula 2:
Li a (Ni x Co y Mn z )O 2   Formula 2
wherein, 0.8<a≦1.2, 0.6≦x≦1, 0≦y≦0.4, 0≦z≦0.4, and x+y+z≦1.2.

6 . The positive active material according to claim 1 , wherein an amount of sulfur is about 0.01 wt % to about 10 wt % based on a total weight of the positive active material.

7 . The positive active material according to claim 1 , wherein the coating layer further comprises at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a transition metal, and a Group 15 element.

8 . The positive active material according to claim 1 , wherein the coating layer further comprises at least one element selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), magnesium (Mg), calcium (Ca), aluminum (Al), silicon (Si), tin (Sn), lead (Pb), manganese (Mn), iron (Fe), chromium (Cr), nickel (Ni), zinc (Zn), zirconium (Zr), thallium (Tl), and nitrogen (N).

9 . The positive active material according to claim 1 , wherein the coating layer is a continuous coating layer.

10 . A positive electrode comprising the positive active material according to claim 1 .

11 . A lithium battery comprising the positive electrode according to claim 10 .

12 . A method of preparing the positive active material according to claim 1 , the method comprising:
coating a surface of a core with a coating solution comprising a sulfate compound to prepare a coated core; and heat-treating the coated core to form a coating layer comprising a sulfur (S) component on the core.

13 . The method of claim 12 , wherein the sulfate compound further comprises at least one element selected from the group consisting of an alkali metal, an alkaline earth metal, a transition metal, and a Group 15 element.

14 . The method of claim 12 , wherein the sulfate compound is represented by Formula 3:

wherein, R is a substituted or unsubstituted aliphatic hydrocarbon group;
X is at least one selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and an ammonium ion; and
1≦a≦5 and 1≦b≦5.

15 . The method of claim 14 , wherein
the substituted or unsubstituted aliphatic hydrocarbon group is a C1-C20 alkyl group; and X is at least one selected from the group consisting of NH 4 , Li, Na, K, Rb, Cs, Mg, Ca, Al, Si, Sri, Pb, Mn, Fe, Cr, Ni, Zn, Zr, and Tl.

16 . The method of claim 12 , wherein the sulfate compound comprises at least one compound selected from the group consisting of sodium dodecyl sulfate (SDS), lithium dodecyl sulfate (LDS), ammonium lauryl sulfate (ALS), and sodium lauryl sulfate (SLS).

17 . The method of claim 12 , wherein an amount of the sulfate compound is about 0.01 parts by weight to about 10 parts by weight based on 100 parts by weight of the core.

18 . The method of claim 12 , further comprising:
washing the core with distilled water before coating the surface of the core with the coating solution.

19 . The method of claim 12 , wherein the heat-treating comprises drying and calcination.

20 . The method of claim 19 , wherein the calcination is performed at a temperature of about 300° C. to about 1000° C. in air.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Choi Jae-Won
• Park Sang-In
• Lim Jae-Hong
• You Yong-Chan

Classifications

• H01M4/366 Primary

  as layered products · CPC title

• H01M10/052

  Li-accumulators · 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

• H01M4/0471

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title