Positive electrode for secondary battery, and secondary battery

Patent metadata

Field	Value
Publication number	US-10033042-B2
Application number	US-201314382297-A
Country	US
Kind code	B2
Filing date	Mar 1, 2013
Priority date	Mar 2, 2012
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

A positive electrode for a secondary battery wherein the electrode includes a collector and a positive electrode active material layer which is stacked upon the collector, and which includes a positive electrode active material, a conductive agent, and a binder; the binder includes a first polymer and a second polymer; the first polymer is a fluorine-containing polymer; the second polymer includes a polymerized moiety having a nitrile group, a polymerized moiety having a hydrophilic group, a polymerized (meth)acrylic acid ester moiety, and a straight-chain polymerized alkylene moiety having a carbon number of at least 4; the proportion of the first polymer and the second polymer in the binder, expressed as a mass ratio, is in the range of 95:5 to 5:95.

First claim

The invention claimed is:

1. A positive electrode for a secondary battery comprising a current collector, and a positive electrode active material layer stacked on said current collector and having a positive electrode active material, a conductive agent and a binder; wherein
said binder includes a first polymer and a second polymer,
said first polymer is fluorine containing polymer,
said second polymer includes a polymer unit having a nitrile group, a polymer unit having a hydrophilic group, (meth)acrylate polymer unit, and a polymer unit of linear alkylene having carbon atoms of 4 or more,
a content ratio of said polymer unit of linear alkylene having carbon atoms of 4 or more in said second polymer is 30 to 60 wt %,
a ratio between said first polymer and said second polymer in said binder is 90:10 to 5:95 in terms of weight ratio, and
an iodine value of said second polymer is 3 to 60 mg/100 mg.

2. The positive electrode for the secondary battery as set forth in claim 1 , wherein said first polymer is at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

3. The positive electrode for the secondary battery as set forth in claim 2 , wherein a content ratio of said polymer unit having nitrile group in said second polymer is 2 to 50 wt %.

4. The positive electrode for the secondary battery as set forth in claim 2 , wherein a content ratio of said polymer unit having hydrophilic group in said second polymer is 0.05 to 20 wt %.

5. The positive electrode for the secondary battery as set forth in claim 2 , wherein carbon atoms of alkyl group binding to non-carbonyl oxygen atom of said (meth)acrylate polymer unit in said second polymer is 4 to 10.

6. The positive electrode for the secondary battery as set forth in claim 2 , wherein a glass transition temperature of said second polymer is 25° C. or less.

7. The positive electrode for the secondary battery as set forth in claim 1 , wherein a content ratio of said polymer unit having nitrile group in said second polymer is 2 to 50 wt %.

8. The positive electrode for the secondary battery as set forth in claim 7 , wherein a content ratio of said polymer unit having hydrophilic group in said second polymer is 0.05 to 20 wt %.

9. The positive electrode for the secondary battery as set forth in claim 7 , wherein carbon atoms of alkyl group binding to non-carbonyl oxygen atom of said (meth)acrylate polymer unit in said second polymer is 4 to 10.

10. The positive electrode for the secondary battery as set forth in claim 1 , wherein a content ratio of said polymer unit having hydrophilic group in said second polymer is 0.05 to 20 wt %.

11. The positive electrode for the secondary battery as set forth in claim 10 , wherein carbon atoms of alkyl group binding to non-carbonyl oxygen atom of said (meth)acrylate polymer unit in said second polymer is 4 to 10.

12. The positive electrode for the secondary battery as set forth in claim 7 , wherein a glass transition temperature of said second polymer is 25° C. or less.

13. The positive electrode for the secondary battery as set forth in claim 1 , wherein carbon atoms of alkyl group binding to non-carbonyl oxygen atom of said (meth)acrylate polymer unit in said second polymer is 4 to 10.

14. The positive electrode for the secondary battery as set forth in claim 1 , wherein a glass transition temperature of said second polymer is 25° C. or less.

15. A secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolytic solution, wherein said positive electrode is the positive electrode for the secondary battery as set forth in claim 1 .

16. The positive electrode for the secondary battery as set forth in claim 1 , wherein said polymer unit of linear alkylene having carbon atoms of 4 or more is formed by hydrogenating at least part of a carbon-carbon double bond of a structural unit formed by polymerizing a conjugated diene monomer having carbon atoms of 4 or more.

Assignees

• Zeon Corp

Inventors

• Fukumine Mayumi
• Kobayashi Kei
• Katada Arinobu

Classifications

• H01M4/623 Primary

  fluorinated polymers · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/622

  being polymers · CPC title

• H01M4/13 Primary

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

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title