Binder composition for positive electrode of lithium ion secondary battery, slurry composition for positive electrode of lithium ion secondary battery and method of producing the same, method of producing positive electrode for lithium ion secondary battery, and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-9876231-B2
Application number	US-201414890664-A
Country	US
Kind code	B2
Filing date	May 14, 2014
Priority date	May 15, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

The disclosed binder composition for the positive electrode of a lithium ion secondary battery includes a binder and an organic dispersion medium, a weight-average molecular weight of the binder being from 100,000 to 2,000,000, and the binder containing 10% to 35% by mass of an ethylenically unsaturated monomer unit containing an acid group, and includes 0.6 to 1.5 equivalents of lithium with respect to the acid group. The disclosed slurry composition for the positive electrode of a lithium ion secondary battery includes this binder composition, a positive electrode active material, and a conductive material.

First claim

The invention claimed is:

1. A binder composition for the positive electrode of a lithium ion secondary battery, comprising:
a binder and an organic dispersion medium,
wherein a weight-average molecular weight of the binder is from 100,000 to 2,000,000, and
wherein the binder contains 10% to 35% by mass of an ethylenically unsaturated monomer unit containing an acid group; and

0.6 to 1.5 equivalents of lithium with respect to the acid group.

2. A slurry composition for the positive electrode of a lithium ion secondary battery, the slurry composition comprising: the binder composition for the positive electrode of a lithium ion secondary battery of claim 1 ; a positive electrode active material; and a conductive material.

3. The slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 , wherein a TI value (ratio of viscosity at 6 rpm to viscosity at 60 rpm) measured with a Brookfield viscometer is from 1 to 4.

4. The slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 , wherein the binder contains 50% to 85% by mass of a (meth)acrylate monomer unit.

5. The slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 , wherein the acid group includes at least one of a carboxylic acid group and a sulfonate group.

6. The slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 , wherein a degree of swelling in electrolysis solution of the binder is 1 to 5 times.

7. The slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 , wherein the positive electrode active material is a lithium nickel composite oxide.

8. A method of producing a positive electrode for a lithium ion secondary battery, the method comprising: forming a positive electrode mixed material layer on a current collector by applying the slurry composition for the positive electrode of a lithium ion secondary battery of claim 2 on the current collector and drying the slurry composition.

9. A lithium ion secondary battery comprising: a positive electrode for a lithium ion secondary battery obtained by the method of claim 8 ; a negative electrode; an electrolysis solution; and a separator.

10. The binder composition for the positive electrode of a lithium ion secondary battery of claim 1 ,
wherein a content percentage of the ethylenically unsaturated monomer unit containing an acid group is 15% by mass or greater.

11. The binder composition for the positive electrode of a lithium ion secondary battery of claim 10 ,
wherein the binder further contains a (meth)acrylate monomer unit and an α,β-unsaturated nitrile monomer unit, and
a content percentage of the α,β-unsaturated nitrile monomer unit is 5% to 30% by mass.

Assignees

• Zeon Corp

Inventors

• Murase Tomoya
• Sugimoto Takumi
• Mesuda Ikuya

Classifications

• H01M4/131

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

• H01M10/052

  Li-accumulators · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/622 Primary

  being polymers · CPC title

• H01M10/0525

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