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

Patent metadata

Field	Value
Publication number	US-12512479-B2
Application number	US-202017428407-A
Country	US
Kind code	B2
Filing date	Aug 11, 2020
Priority date	Aug 12, 2019
Publication date	Dec 30, 2025
Grant date	Dec 30, 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-based coating layer formed on a surface of the positive electrode active material layer. The two types of positive electrode active materials are each represented by Chemical Formula 1 below. The carbon-based coating layer includes a sphere-type conductive material and a binder, where the binder is included in an amount of 5 parts by weight or more and less than 10 parts by weight with respect to 100 parts by weight of the carbon-based coating layer.

Li 1+a Ni x Co y M z O 2   [Chemical Formula 1]

In Chemical Formula 1, 0≤a≤0.5, 0<x<1, 0<y<1, 0<z<1, and M is at least one of Mn and Al.

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, wherein 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 first binder; and a carbon-based coating layer on a surface of the positive electrode active material layer, wherein the two types of positive electrode active materials with different average particle diameters are each represented by Chemical Formula 1 below, the carbon-based coating layer has a thickness of 2 μm to 20 μm, the carbon-based coating layer includes a sphere-type conductive material and a second binder, and the carbon-based coating layer includes the second binder in an amount of 5 parts by weight or more and less than 10 parts by weight with respect to 100 parts by weight of the carbon-based coating layer:
Li 1+a Ni x Co y M z O 2   [Chemical Formula 1]

wherein, 0≤a≤0.5, 0<x<1, 0<y<1, 0<<1, and M is at least one of Mn and Al, wherein the sphere-type conductive material is carbon black having a specific surface area of 50 m 2 /g to 500 m 2 /g, and wherein the sphere-type conductive material has a density of 1.0 g/cm 3 to 3.0 g/cm 3 .

2 . The positive electrode of claim 1 , wherein the sphere-type conductive material is one or more selected from acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black.

3 . The positive electrode of claim 1 , wherein the two types of positive electrode active materials with different average particle diameters (D 50 ) have a bimodal particle diameter distribution including first positive electrode active material particles having an average particle diameter (D 50 ) of 8 μm to 20 μm and second positive electrode active material particles having a smaller average particle diameter (D 50 ) than the average particle diameter (D 50 ) of the first positive electrode active material particles.

4 . The positive electrode of claim 3 , wherein the second positive electrode active material particles have an average particle diameter (D 50 ) of 10% or more and less than 40% of the average particle diameter (D 50 ) of the first positive electrode active material particles.

5 . The positive electrode of claim 3 , wherein the second positive electrode active material particles have an average particle diameter (D 50 ) of 0.8 μm or more and less than 8 μm.

6 . The positive electrode of claim 3 , 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.

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

8 . The positive electrode of claim 3 , wherein the first positive electrode active material particles are disposed within space between the second positive electrode active material particles.

9 . The positive electrode of claim 1 , wherein the sphere-type conductive material has a density of 1.0 g/cm 3 to 2.5 g/cm 3 .

10 . The positive electrode of claim 1 , wherein the sphere-type conductive material has a density of 1.3 g/cm 3 to 2.5 g/cm 3 .

Assignees

• Lg Chemical Ltd

Inventors

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

Classifications

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

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

• H01M4/364 Primary

  as mixtures · CPC title