Binder composition for secondary battery positive electrode, slurry composition for secondary battery positive electrode, secondary battery positive electrode, and secondary battery

Patent metadata

Field	Value
Publication number	US-9601775-B2
Application number	US-201214360887-A
Country	US
Kind code	B2
Filing date	Nov 28, 2012
Priority date	Nov 28, 2011
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

Provided are a binder composition which has high electrolyte resistance characteristics, and a secondary battery which uses a positive electrode using the binder composition for high-temperature cycle characteristics. [Solution] The binder composition for the secondary battery positive electrode according to the present invention contains a polymerized unit which contains a nitrile group; a polymerized unit of (meth) acrylic acid ester; a polymerized unit which contains a hydrophilic group; and a polymerized unit of linear alkylene having a carbon number of at least four. In a mixed solvent in which a volume ratio EC:DEC between ethylene carbonate (EC) and diethyl carbonate (DEC) at 20° C. is 1:2, a degree of swelling with respect to an electrolyte in which LiPF 6 is dissolved to have a concentration of 1.0 mol/L is between 100% and 500%.

First claim

The invention claimed is:

1. A binder composition for the secondary battery positive electrode comprising a binder including a polymer unit having nitrile group, (meth)acrylate polymer unit, a polymer unit having hydrophilic group, and a polymer unit of linear alkylene wherein the linear alkylene has carbon atoms of 4 or more; wherein,
a swelling degree of said binder in an electrolytic solution dissolved with LiPF 6 of a concentration of 1.0 mol/L in a mixture solution formed by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) having the volume ratio at 20° C. of EC:DEC=1:2 is 100 to 500%.

2. The binder composition for the secondary battery positive electrode as set forth in claim 1 , wherein a content ratio of said (meth)acrylate polymer unit is 5 to 50 wt %.

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

4. The binder composition for the secondary battery positive electrode as set forth in claim 3 , wherein a content ratio of said polymer unit having hydrophilic group is 0.05 to 20 wt %.

5. The binder composition for the secondary battery positive electrode as set forth in claim 3 , wherein carbon atoms of alkyl groups bonding with a non-carbonyl oxygen atom of said (meth)acrylate polymer unit is 4 to 10.

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

7. The binder composition for the secondary battery positive electrode as set forth in claim 2 , wherein carbon atoms of alkyl groups bonding with a non-carbonyl oxygen atom of said (meth)acrylate polymer unit is 4 to 10.

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

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

10. The binder composition for the secondary battery positive electrode as set forth in claim 8 , wherein carbon atoms of alkyl groups bonding with a non-carbonyl oxygen atom of said (meth)acrylate polymer unit is 4 to 10.

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

12. The binder composition for the secondary battery positive electrode as set forth in claim 11 , wherein carbon atoms of alkyl groups bonding with a non-carbonyl oxygen atom of said (meth)acrylate polymer unit is 4 to 10.

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

14. The binder composition for the secondary battery positive electrode as set forth in claim 1 , wherein a solubility parameter (SP value) of said binder is 9.0 (cal/cm 3 ) 1/2 or more and less than 11 (cal/cm 3 ) 1/2 .

15. The binder composition for the secondary battery positive electrode as set forth in claim 1 , wherein an iodine value of said binder is 3 to 60 mg/100 mg.

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

17. A slurry composition for the secondary battery positive electrode comprising a positive electrode active material and the binder composition for the secondary battery electrode as set forth in claim 1 .

18. A secondary battery positive electrode wherein the positive electrode active materials made of the slurry composition for the secondary battery positive electrode as set forth in claim 17 is formed on a current collector.

19. A secondary battery comprising a positive electrode, a negative electrode and an electrolytic solution, wherein and said positive electrode is the secondary battery positive electrode as set forth in claim 18 .

20. A production method of a secondary battery positive electrode comprising steps of coating and drying the slurry composition for the secondary battery as set forth in claim 17 on at least to one face of the current collector.

21. The positive electrode for the secondary battery as set forth in claim 1 , wherein said polymer unit of linear alkylene wherein the linear alkylene has 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.

22. The binder composition for the secondary battery positive electrode as set forth in claim 1 , wherein a content ratio of said polymer unit of linear alkylene is 20 to 98 wt %.

Assignees

• Zeon Corp

Inventors

• Fukumine Mayumi
• Kobayashi Kei

Classifications

• H01M4/139

  Processes of manufacture · CPC title

• Y02P70/54

  Cross-Sectional Technologies · mapped topic

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M2220/30

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

• H01M10/0525

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