Electrode mixture, method for producing electrode mixture, electrode structure, method for producing electrode structure, and secondary battery

Patent metadata

Field	Value
Publication number	US-11322744-B2
Application number	US-201716348216-A
Country	US
Kind code	B2
Filing date	Nov 9, 2017
Priority date	Nov 15, 2016
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

To provide an electrode mixture that suppresses gelling of an electrode mixture slurry and maintains a high binding capacity between an electrode active material and a current collector even after an extended period of time has elapsed since an electrode mixture slurry was produced. The electrode mixture includes: a binder composition—containing a first copolymer of vinylidene fluoride and a polar group-containing compound; and a second copolymer of vinylidene fluoride and chlorotrifluoroethylene—; and an electrode active material of lithium oxide having a pH of water when extracted with water of not less than 10.5.

First claim

The invention claimed is:

1. An electrode mixture comprising:
an electrode active material provided on a current collector; and
a binder composition for binding the electrode active material to the current collector, wherein
the binder composition comprises a first copolymer of vinylidene fluoride and a polar group-containing compound; and a second copolymer of vinylidene fluoride and chlorotrifluoroethylene,
a compounding ratio of the first copolymer and the second copolymer comprised in the binder composition is from 90:10 to 50:50 in terms of a mass ratio,
the electrode active material comprises a lithium metal oxide, and
a pH of the electrode active material is not less than 10.5, the pH of the electrode active material determined by extracting the lithium metal oxide with water,
wherein the lithium metal oxide is a binary lithium metal oxide represented by Formula (2):
LiNi x N1 y O 2   (2)

where N1 represents Co or Mn, 0.5≤x≤1, and 0<y≤0.5, or
a ternary lithium metal oxide represented by Formula (3):
LiNi x Co y N2 z O 2   (3)

where N2 represents either Mn or Al, 0.5≤x≤1, 0<y≤0.5, and 0<z≤0.5.

2. The electrode mixture according to claim 1 , wherein
the first copolymer comprises from 90.00 to 99.99 mol % of vinylidene fluoride units, and
the second copolymer comprises from 70.00 to 99.50 mol % of vinylidene fluoride units (based on the total of the vinylidene fluoride units; and constituent units derived from the polar group-containing compound or the chlorotrifluoroethylene being 100.00 mol %).

3. The electrode mixture according to claim 1 , wherein the polar group-containing compound comprises a carboxyl group.

4. The electrode mixture according to claim 1 , wherein the polar group-containing compound is acrylic acid, an acrylic acid derivative, or an unsaturated dibasic acid monoester.

5. A method for producing an electrode mixture, the method comprising kneading:
a first copolymer obtained by copolymerizing vinylidene fluoride and a polar group-containing compound;
a second copolymer obtained by copolymerizing vinylidene fluoride and chlorotrifluoroethylene; and
a lithium metal oxide, wherein
a compounding ratio of the first copol mer and the second copolymer is from 90:10 to 50:50 in terms of a mass ratio,
a pH of the lithium metal oxide is not less than 10.5, the pH of the lithium metal oxide determined by extracting the lithium metal oxide with water, and
the lithium metal oxide is a binary lithium metal oxide represented by Formula (2):
LiNi x N1 y O 2   (2)

where N1 represents Co or Mn, 0.5≤x≤1, and 0<y≤0.5, or
a ternary lithium metal oxide represented by Formula (3):
LiNi x Co y N2 z O 2   (3)

where N2 represents either Mn or Al, 0.5≤x≤1, 0<y≤0.5, and 0<z≤0.5.

6. An electrode structure comprising:
a current collector; and
an electrode mixture layer provided on the current collector, wherein
the electrode mixture layer comprises at least a binder composition and an electrode active material,
the binder composition comprises a first copolymer of vinylidene fluoride and a polar group-containing compound; and a second copolymer of vinylidene fluoride and chlorotrifluoroethylene,
a compounding ratio of the first copolymer and the second copolymer comprised in the binder composition is from 90:10 to 50:50 in terms of a mass ratio,
the electrode active material comprises a lithium metal oxide, and
a pH of the electrode active material is not less than 10.5, the pH of the electrode active material determined by extracting the electrode active material with water, and
the lithium metal oxide is a binary lithium metal oxide represented by Formula (2):
LiNi x N1 y O 2   (2)

where N1 represents Co or Mn, 0.5≤x≤1, and 0<y≤0.5, or
a ternary lithium metal oxide represented by Formula (3):
LiNi x Co y N2 z O 2   (3)

where N2 represents either Mn or Al, 0.5≤x≤1, 0<y0.5, and 0<z≤0.5.

7. A method for producing the electrode structure described in claim 6 , the method comprising:
applying and drying an electrode mixture comprising the binder composition, the lithium metal oxide, and a solvent onto a surface of the current collector to form a coating film on the surface of the current collector; and
heat treating the coating film to obtain the electrode mixture layer.

8. A secondary battery comprising the electrode structure described in claim 6 .

Assignees

• Kureha Corp

Inventors

• Aoki Kenta
• Aoki Shoko
• Kobayashi Shota
• Tada Yasuhiro

Classifications

• H01M4/1391

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

• H01M4/131 Primary

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

• H01M4/623 Primary

  fluorinated polymers · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M10/0525

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