Cathode active material and method of preparing the same

Patent metadata

Field	Value
Publication number	US-9905840-B2
Application number	US-201414515036-A
Country	US
Kind code	B2
Filing date	Oct 15, 2014
Priority date	Jul 26, 2013
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Provided are a cathode active material including polycrystalline lithium manganese oxide and a sodium-containing coating layer on a surface of the polycrystalline lithium manganese oxide, and a method preparing the same.
Since the cathode active material according to an embodiment of the present invention may prevent direct contact between the polycrystalline lithium manganese oxide and an electrolyte solution by including the sodium-containing coating layer on the surface of the polycrystalline lithium manganese oxide, the cathode active material may prevent side reactions between the cathode active material and the electrolyte solution. In addition, since limitations, such as the Jahn-Teller distortion and the dissolution of Mn 2+ , may be addressed by structurally stabilizing the polycrystalline lithium manganese oxide, tap density, life characteristics, and charge and discharge capacity characteristics of a secondary battery may be improved.

First claim

The invention claimed is:

1. A cathode active material comprising:
polycrystalline lithium manganese oxide represented by Chemical Formula 1
Li (1+x) Mn (2−x−y) Al y O (4−z)   <Chemical Formula 1>

where x, y, and z respectively satisfy 0≦x≦0.2, 0<y≦0.2, and 0≦z≦0.2; and
a sodium-containing coating layer comprising Na 2 O on a surface of the polycrystalline lithium manganese oxide, wherein a tap density of the cathode active material is in a range of 1.7 g/cc to 2.5 g/cc, and
wherein the polycrystalline manganese oxide has a cubic structure.

2. The cathode active material of claim 1 , wherein a thickness of the sodium-containing coating layer is in a range of 1 nm to 500 nm.

3. The cathode active material of claim 1 , wherein the polycrystalline lithium manganese oxide particles are in a form of secondary particles in which two or more primary particles having an average crystal diameter of 152 nm to 300 nm are agglomerated.

4. The cathode active material of claim 3 , wherein an average particle diameter (D 50 ) of the secondary particle is in a range of 3 μm to 20 μm.

5. The cathode active material of claim 1 , wherein I(311)/I(111) of the cathode active material is 40% or more when a peak intensity ratio of I(111)/I(111) is defined as 100% in X-ray diffraction analysis.

6. The cathode active material of claim 1 , wherein I(400)/I(111) and I(440)/I(111) of the cathode active material are respectively 40% or more and 20% or more when a peak intensity ratio of I(111)/I(111) is defined as 100% in X-ray diffraction analysis.

7. The cathode active material of claim 1 , wherein a full width at half maximum (FWHM) of a (311) peak of the cathode active material in X-ray diffraction analysis is 0.3 degrees or less.

8. The cathode active material of claim 1 , wherein a Brunauer-Emmett-Teller (BET) specific surface area of the cathode active material is in a range of 0.1 m 2 /g to 1.0 m 2 /g.

9. The cathode active material of claim 1 , wherein the lithium manganese oxide is doped with at least one sodium (Na) atoms of sodium-containing oxide, and the lithium manganese oxide has a concentration gradient in which an amount of the Na decreases from the surface of the lithium manganese oxide to inside thereof.

10. A cathode comprising the cathode active material of claim 1 .

11. A lithium secondary battery comprising the cathode of claim 10 .

Assignees

• Lg Chemical Ltd

Inventors

• Kwak Ick Soon
• Cho Seung Beom
• Chae Hwa Seok

Classifications

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M4/505

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

• C01P2002/52

  containing elements as dopants · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

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