Positive electrode for lithium secondary battery and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-12368160-B2
Application number	US-202017427815-A
Country	US
Kind code	B2
Filing date	Aug 11, 2020
Priority date	Aug 12, 2019
Publication date	Jul 22, 2025
Grant date	Jul 22, 2025

Abstract

A positive electrode includes: a positive electrode active material layer formed on a surface of a positive electrode current collector, including two types of positive electrode active materials with different average particle diameters (D 50 ), a conductive material, and a binder; and a carbon nanotube coating layer formed on a surface of the positive electrode active material layer, including carbon nanotubes and a binder: The two types of positive electrode active materials include first positive electrode active material particles which have an average particle diameter (D 50 ) of 8 μm to 20 μm and second positive electrode active material particles in the form of a single particle which have a smaller average particle diameter (D 50 ) than the average particle diameter (D 50 ) of the first positive electrode active material particles, and the positive electrode active material layer and the carbon nanotube coating layer are formed in a thickness ratio of 90:10 to 99:1.

First claim

The invention claimed is:

1. A positive electrode comprising:
a positive electrode active material layer on a surface of a positive electrode current collector, where the positive electrode active material layer includes two types of positive electrode active materials with different average particle diameters (D 50 ), a conductive material, and a binder; and
a carbon nanotube coating layer on a surface of the positive electrode active material layer, wherein the carbon nanotube coating layer includes carbon nanotubes and a binder,
wherein the two types of positive electrode active materials with different average particle diameters have a bimodal particle diameter distribution, in which first positive electrode active material particles have an average particle diameter (D 50 ) of 8 μm to 20 μm and second positive electrode active material particles in the form of a single particle have an average particle diameter (D 50 ) of 3 μm to 6 μm,
wherein a thickness ratio of the positive electrode active material layer and the carbon nanotube coating layer is 90:10 to 99:1,
wherein the single particle is at least one of a non-agglomerated primary particle and a secondary particle formed of 10 or less primary particles,
wherein the primary particle is a smallest particle unit observable through scanning electron microscopy,
wherein the second positive electrode active material has crystalline grains with a size of greater than 150 nm to 250 nm, and
wherein the first positive electrode active material has crystalline grains with a size of 120 nm to 150 nm.

2. The positive electrode of claim 1 , wherein the carbon nanotube coating layer includes the carbon nanotubes and the binder in a weight ratio of 80:20 to 95:5.

3. The positive electrode of claim 1 , wherein the first positive electrode active material and the second positive electrode active material are each independently represented by the following Chemical Formula 1:
[Chemical Formula 1]
Li 1+a Ni x Co y M z O 2
wherein, 0≤a≤0.5, 0<x<1, 0<y<1, 0<z<1, and M is at least one of Mn and Al.

4. The positive electrode of claim 1 , wherein the first positive electrode active material includes primary particles having an average particle diameter of 0.5 μm to 4 μm.

5. The positive electrode of claim 1 , wherein the first positive electrode active material and the second positive electrode active material are included in a weight ratio of 9:1 to 6:4.

6. A lithium secondary battery comprising the positive electrode according to claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Jin Joo Hong
• You Min Kyu
• Shin Sun Sik
• Lee Kyung Lok
• Shin Ji A

Classifications

• H01M10/052

  Li-accumulators · CPC title

• H01M4/131 Primary

  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

• H01M2004/021

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

• H01M4/625

  Carbon or graphite · CPC title