Composite cathode active material, method of preparing the same, and cathode and lithium battery including the composite cathode active material

Patent metadata

Field	Value
Publication number	US-10283770-B2
Application number	US-201514972216-A
Country	US
Kind code	B2
Filing date	Dec 17, 2015
Priority date	Dec 18, 2014
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A composite cathode active material, including a nickel-based lithium transition metal oxide secondary particle, the nickel-based lithium transition metal oxide secondary particle including a coating layer containing lithium and cobalt on a surface of a primary particle of the secondary particle.

First claim

What is claimed is:

1. A composite cathode active material, comprising a nickel-based lithium transition metal oxide secondary particle, the nickel-based lithium transition metal oxide secondary particle including a coating layer containing lithium and cobalt on a surface of a primary particle of the secondary particle,
wherein a concentration of the cobalt has a concentration gradient that continuously decreases from the coating layer to a center of the primary particle wherein the nickel-based lithium transition metal oxide is a compound represented by Formula 1:
Li a Ni 1 −x−y Co x M y O 2+α   [Formula 1]

wherein, in Formula 1, 0.9<a<1.5, 0<x<0.5, 0<y<1, and −0.1 ≤α≤0.1; and
M is one or more of Mg, Ca, Sr, Ba, Ti, Zr, Nb, Mo, W, Zn, Al, Si, Mn, Cr, Fe, V, or a rare earth element, and
wherein the coating layer includes a compound represented by Formula 2:
Li a Ni 1−x−y−z Co x M y Mn z O 2   [Formula 2]

wherein, in Formula 2, M is a transition metal; and
0.9<a<1.5, 0<x≤0.3, 0≤y≤0.1, 0<z≤0.3.

2. The composite cathode active material as claimed in claim 1 , wherein an amount of cobalt included in the coating layer is greater than about 0 mol % to about 30 mol % or less based on a total amount of the cobalt and the other transition metal.

3. The composite cathode active material as claimed in claim 1 , wherein a thickness of the coating layer is about 20 nm or less.

4. The composite cathode active material as claimed in claim 1 , wherein the coating layer includes:
i) a product obtained by a sol-gel reaction of a composition including a lithium salt and a cobalt salt, or
ii) a nickel-based lithium transition metal oxide and a product obtained by a sol-gel reaction of a composition including a lithium salt and a cobalt salt.

5. The composite cathode active material as claimed in claim 4 , wherein, in the coating layer, an amount of i) the product obtained by a sol-gel reaction of a composition including a lithium salt and a cobalt salt, or ii) the nickel-based lithium transition metal oxide and a product obtained by a sol-gel reaction of a composition including a lithium salt and a cobalt salt, is in a range of about 0.5 parts to about 3 parts by weight based on 100 parts by weight of the composite cathode active material.

6. A cathode, comprising the composite cathode active material as claimed in claim 1 .

7. A lithium battery, comprising the cathode as claimed in claim 6 .

8. The composite cathode active material as claimed in claim 1 , wherein the primary particle of the secondary particle has an average particle diameter of about 200 nm to about 1 μM.

9. The composite cathode active material as claimed in claim 1 , wherein:
an amount of cobalt included in the coating layer is 20 mol % to 28 mol %,
an amount of manganese included in the coating layer is 12 mol % to 20 mol %, and
an amount of nickel included in the coating layer 52 mol % to 60 mol %,
all mol % being based on a total amount of the cobalt and the other transition metal.

10. The composite cathode active material as claimed in claim 1 , wherein an intermediate region having a mixed phase is formed between the primary particle and the coating layer.

11. The composite cathode active material as claimed in claim 1 , wherein the primary particle has a crystalline structure of a layered structure (Fm3m), the coating layer has a compound having a crystalline structure of a rock-salt layered structure (R3m), and a mixed phase is between the primary particle and the coating layer.

12. A method of preparing the composite cathode active material as claimed in claim 1 , the method comprising:
performing a sol-gel reaction of a nickel-based lithium transition metal oxide and a composition including a lithium salt and a cobalt salt; and
heat-treating a product of the sol-gel reaction in an oxidizing gas atmosphere at a temperature in a range of about 600° C. to about 900° C.

Assignees

• Samsung Sdi Co Ltd
• Unist Ulsan National Inst Ofscience & Tech
• Ulsan Nat Inst Science & Tech Unist

Inventors

• Cho Kwanghwan
• Cho Jaephil
• Kim Hyejung

Classifications

• H01M4/366

  as layered products · CPC title

• C01G53/50

  of the type (MnO2)n-, e.g. Li(NixMn1-x)O2 or Li(MyNixMn1-x-y)O2 · CPC title

• C01P2004/80

  Particles consisting of a mixture of two or more inorganic phases · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2002/76

  by a space-group or by other symmetry indications · CPC title