Cathode and lithium battery including the same

Patent metadata

Field	Value
Publication number	US-2020075930-A1
Application number	US-201916534206-A
Country	US
Kind code	A1
Filing date	Aug 7, 2019
Priority date	Aug 28, 2018
Publication date	Mar 5, 2020
Grant date	—

Abstract

A cathode includes: a cathode active material comprising a lithium transition metal oxide; a conductive material; and a binder, wherein the lithium transition metal oxide includes nickel and a transition metal other than nickel, wherein the lithium transition metal oxide has a layered crystal structure, wherein a content of the nickel is 30 mole percent or greater, based on a total number of moles of transition metals of the lithium transition metal oxide, wherein the conductive material comprises a linear carbon conductive material, wherein the binder includes a first binder, wherein the first binder including fluorine and a polar functional group, and a second binder, which does not include fluorine, and wherein an amount of the linear carbon conductive material is 0.1 weight percent or greater, based on a total combined weight of the cathode active material, the conductive material, and the binder.

First claim

What is claimed is:

1 . A cathode, the cathode comprising:
a cathode active material comprising a lithium transition metal oxide; a conductive material; and a binder, wherein the lithium transition metal oxide comprises nickel and a transition metal other than nickel, wherein the lithium transition metal oxide has a layered crystal structure, wherein a content of the nickel is 30 mole percent or greater, based on a total number of moles of transition metals of the lithium transition metal oxide, wherein the conductive material comprises a linear carbon conductive material, wherein the binder comprises
a first binder comprising fluorine and a polar functional group and
a second binder, which does not comprise fluorine, and
wherein an amount of the linear carbon conductive material is 0.1 weight percent or greater, based on a total combined weight of the cathode active material, the conductive material, and the binder.

2 . The cathode of claim 1 , wherein the linear carbon conductive material comprises carbon nanotube, carbon nanofiber, carbon nanorod, or a combination thereof.

3 . The cathode of claim 1 , wherein the conductive material further comprises a particulate carbon conductive material in addition to the linear carbon conductive material,
wherein an aspect ratio of the linear carbon conductive material is 2 or greater, and wherein an aspect ratio of the particulate carbon conductive material is less than 2.

4 . The cathode of claim 3 , wherein the particulate carbon conductive material comprises carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, natural graphite, artificial graphite, or a combination thereof.

5 . The cathode of claim 3 , wherein a weight ratio of the linear carbon conductive material to the particulate carbon conductive material is from about 90:10 to about 10:90.

6 . The cathode of claim 1 , wherein an amount of the first binder is 2 weight percent or less, based on the total combined weight of the cathode active material, the conductive material, and the binder.

7 . The cathode of claim 1 , wherein the first binder comprises:
a repeating unit comprising a polar functional group; a repeating unit derived from vinylidene fluoride; and optionally, a repeating unit derived from tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, a fluorovinyl group-containing monomer, a perfluoroalkyl vinyl ether, or a combination thereof, wherein a weight average molecular weight of the first binder is 1,000,000 Daltons or greater.

8 . The cathode of claim 1 , wherein the polar functional group of the first binder comprises a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, a salt thereof, or a combination thereof.

9 . The cathode of claim 1 , further comprising a third binder comprising fluorine, wherein the third binder does not comprise a polar functional group.

10 . The cathode of claim 9 , wherein the third binder comprises a repeating unit derived from vinylidene fluoride and the third binder has a weight average molecular weight of 1,000,000 Daltons or less.

11 . The cathode of claim 9 , wherein a weight ratio of the first binder to the third binder is from about 90:10 to about 10:90.

12 . The cathode of claim 1 , wherein the second binder comprises a cyano group.

13 . The cathode of claim 1 , wherein the second binder comprises a repeating unit derived from an acrylonitrile-containing monomer and a repeating unit derived from an olefin-containing monomer.

14 . The cathode of claim 1 , wherein the lithium transition metal oxide is a compound represented by Formula 1:
Li a Ni x Co y M z O 2-b A b   Formula 2
wherein, in Formula 2, 1≤a≤1.2, 0≤b≤0.2, 0.3≤x<1, 0<y≤0.4, 0<z≤0.4, x+y+z=1, M comprises manganese, vanadium, magnesium, gallium, silicon, tungsten, molybdenum, iron, chromium, copper, zinc, titanium, aluminum, boron, or a combination thereof, and A is F, S, Cl, Br, or a combination thereof.

15 . The cathode of claim 1 , wherein the lithium transition metal oxide is a compound represented by Formula 3 or 4:
LiNi x Co y Mn z O 2   Formula 3
LiNi x Co y Al z′ O 2   Formula 4
wherein, in Formula 2, 0.3≤x<1, 0<y≤0.4, and 0<z≤0.4, and wherein in Formula 3, 0.3≤x′<1, 0<y′≤0.4, and 0<z′≤0.4.

16 . The cathode of claim 1 , wherein an amount of the cathode active material is from about 95 weight percent to about 98.9 weight percent, an amount of the conductive material is from about 1 weight percent to 4 weight percent, and an amount of the binder is from about 0.01 weight percent to about 2 weight percent, based on the total combined weight of the cathode active material, the conductive material, and the binder, and
wherein a loading of the cathode is 3 milliampere hours per square centimeter or greater.

17 . The cathode of claim 16 , wherein the loading of the cathode is 5 milliampere hours per square centimeter or greater.

18 . The cathode of claim 1 , wherein the cathode has a bending range of motion of 90 degrees or greater during a flexural property test performed in accordance with ASTM D790.

19 . The cathode of claim 1 , wherein a maximum bending strength of the cathode obtained from a flexural property test performed in accordance with ASTM D790 is 1 Newton or less.

20 . The cathode of claim 1 , wherein a peel strength of the cathode obtained from a 180-degree peel strength test performed in accordance with ASTM D3330 is 0.3 gram-force per millimeter or greater.

21 . A lithium battery comprising:
a cathode according to claim 1 ; an anode; and an electrolyte located between the cathode and the anode.

Assignees

• Samsung Electronics Co Ltd
• Samsung Sdi Co Ltd

Inventors

• Kim Youngsoo
• Ryu Younggyoon
• Yoon Jaegu
• Lee Seungyeon

Classifications

• H01M4/623

  fluorinated polymers · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/131 Primary

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

• H01M4/525 Primary

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/622

  being polymers · CPC title