Positive Electrode Active Material for Lithium Rechargeable Battery, Method of Producing the Same, and Lithium Rechargeable Battery Including the Same

Patent metadata

Field	Value
Publication number	US-2020067091-A1
Application number	US-201916549545-A
Country	US
Kind code	A1
Filing date	Aug 23, 2019
Priority date	Aug 24, 2018
Publication date	Feb 27, 2020
Grant date	—

Abstract

A surface of a LiCoO2-based positive electrode active material to have a rock salt crystal structure is provided. Specifically, a positive electrode active material for a lithium rechargeable battery is provided, including: a core particle containing lithium cobalt oxide doped with aluminum (Al); and a coating layer positioned on a surface of the core particle and containing a cobalt(Co)-based compound having a rock salt crystal structure. A method of producing the positive electrode active material is also provided using a solid-phase method. The positive electrode active material can be applied to a positive electrode, lithium rechargeable battery, battery module, battery pack, and the like.

First claim

1 . A positive electrode active material for a lithium rechargeable battery, comprising:
a core particle comprising lithium cobalt oxide doped with aluminum (Al); and a coating layer on a surface of the core particle, wherein the coating layer comprises a cobalt-based compound having a rock salt crystal structure.

2 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
the cobalt-based compound having a rock salt crystal structure is cobalt(II) oxide.

3 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
the coating layer further comprises cobalt, lithium cobalt oxide, or a combination thereof.

4 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
the coating layer has an island form in which the surface of the core particle is coated with the cobalt-based compound having a rock salt crystal structure.

5 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
a weight ratio (core particle:coating layer) of the core particle to the coating layer is 1,000:0.2 to 1,000:10.

6 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
a thickness of the coating layer is 1 to 50 nm.

7 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
a D50 particle diameter of the coating particle is 12 to 25 μm.

8 . The positive electrode active material for a lithium rechargeable battery of claim 7 , wherein:
the core particle comprises:
a first region in which a crystal structure of the lithium cobalt oxide doped with Al is a layered structure; and
a second region in which a crystal structure of the lithium cobalt oxide doped with Al is a spinel structure.

9 . The positive electrode active material for a lithium rechargeable battery of claim 8 , wherein:
the first region is represented by the following Formula 1,
Li a Co (1-x-y-z) Al x M1 y M2 z O 2   [Formula 1]

wherein M1 and M2 are each independently one selected from the group consisting of Ti, Mg, Zr, Ba, Ca, Ta, Nb, and Mo, and a, x, y, and z are values satisfying 0.95≤a≤1.05, 0<x≤0.02, 0≤y≤0.02, and 0≤z≤0.02, respectively.

10 . The positive electrode active material for a lithium rechargeable battery of claim 8 , wherein:
the second region is represented by the following Formula 2,
Li a-m Co (1-x-y-z) Al x M1 y M2 z O 2   [Formula 2]

wherein M1 and M2 are each independently one selected from the group consisting of Ti, Mg, Zr, Ba, Ca, Ta, Nb, and Mo, and a, x, y, z, and m are values satisfying 0.95≤a≤1.05, 0<x≤0.02, 0≤y≤0.02, 0≤z≤0.02, and 0<m<0.75, respectively.

11 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
when the battery is stored at a temperature range of 50 to 80° C. for one week and then discharged at a voltage of 4.4 V, a Co elution amount per 1 g of the positive electrode active material is 100 to 200 ppm/g.

12 . A method of producing a positive electrode active material for a lithium rechargeable battery, comprising:
mixing a core particle comprising lithium cobalt oxide doped with Al and a cobalt raw material comprising tricobalt tetraoxide (Co 3 O 4 ), cobalt(II) hydroxide (Co(OH) 2 ), or a mixture thereof; and calcining the mixture of the cobalt raw material and the core particle.

13 . The method of claim 12 , wherein:
in the calcining of the mixture of the cobalt raw material and the core particle, a phase of the cobalt raw material is changed into a cobalt-based compound having a rock salt crystal structure and a surface of the core particle is coated with the cobalt-based compound having a rock salt crystal structure.

14 . The method of claim 12 , wherein:
in the mixing of the cobalt raw material with the core particle, a weight ratio (core particle:cobalt raw material) of the core particle to the cobalt raw material is 1,000:0.2 to 1,000:10.

15 . The method of claim 12 , wherein:
in the calcining of the mixture of the cobalt raw material and the core particle, a calcination temperature is 800 to 1,200° C.

16 . The method of claim 12 , wherein:
in the calcining of the mixture of the cobalt raw material and the core particle, a calcination time is 2 to 10 hours.

17 . A lithium rechargeable battery, comprising:
a positive electrode containing the positive electrode active material of claim 1 ; an electrolyte; and a negative electrode.

18 . The positive electrode active material for a lithium rechargeable battery of claim 8 , wherein the second region is a mixed structure of the spinel structure and the layered structure from an interface with the first region to the surface of the core particle.

19 . The positive electrode active material for a lithium rechargeable battery of claim 1 , wherein:
when the battery is stored at a temperature of 60° C. for one week and then discharged at a voltage of 4.5 V, a Co elution amount per 1 g of the positive electrode active material may be 1,500 to 2,500 ppm/g.

Assignees

• Lg Chemical Ltd
• Lg Chem Ltd Seoul Korea Republic Of

Inventors

• Jo Chi Ho
• Hur Hyuck
• Kim Seul Ki
• Jung Wang Mo
• Han Gi Beom

Classifications

• H01M4/366 Primary

  as layered products · CPC title

• H01M4/0471

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

• H01M4/1391

  of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title