Separator including coating layer and battery including the same

Patent metadata

Field	Value
Publication number	US-9634311-B2
Application number	US-201313778332-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Feb 29, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A separator includes a coating layer, the coating layer containing a polyvinylidene fluoride homopolymer, a polyvinylidene fluoride-hexafluoropropylene copolymer, a solvent, and inorganic particles, the solvent being present in an amount of about 100 ppm or less in the coating layer.

First claim

What is claimed is:

1. A separator, comprising:
a polyolefin base film and a coating layer on one or both sides of the polyolefin base film, the coating layer containing, based on 100 parts by weight of the coating layer in terms of solid content, 5 to 10 parts by weight of a polyvinylidene fluoride homopolymer, 5 to 20 parts by weight of a polyvinylidene fluoride-hexafluoropropylene copolymer, a solvent, and 70 to 90 parts by weight of inorganic particles, the solvent being present in an amount of 100 ppm or less in the coating layer,
wherein the polyvinylidene fluoride homopolymer has a weight average molecular weight of 1,000,000 g/mol or more and the polyvinylidene fluoride-hexafluoropropylene copolymer has a weight average molecular weight of 800,000 g/mol or less.

2. The separator as claimed in claim 1 , wherein the polyvinylidene fluoride homopolymer has a weight average molecular weight of 1,000,000 g/mol to 1,200,000 g/mol, and the polyvinylidene fluoride-hexafluoropropylene copolymer has a weight average molecular weight of 600,000 g/mol to 800,000 g/mol.

3. The separator as claimed in claim 1 , wherein the solvent has a boiling point of 140° C. or more.

4. The separator as claimed in claim 3 , wherein the solvent includes one or more of dimethylformamide, dimethylsulfoxide, dimethylacetamide, or N-methylpyrrolidone.

5. The separator as claimed in claim 1 , wherein the inorganic particles include one or more of Al 2 O 3 particles, SiO 2 particles, B 2 O 3 particles, Ga 2 O 3 particles, TiO 2 particles, or SnO 2 particles.

6. The separator as claimed in claim 1 , wherein the coating layer is formed by dip coating.

7. The separator as claimed in claim 1 , wherein the coating layer has a peel strength of 50 gf/cm 2 or more.

8. The separator as claimed in claim 1 , wherein an adhesive strength between the coating layer and electrodes of a battery is 20 gf/cm 2 or more.

9. The separator as claimed in claim 8 , wherein the battery is a lithium rechargeable battery.

10. The separator as claimed in claim 9 , wherein:
the electrodes include a positive electrode and a negative electrode,
the positive electrode is selected from the group of a lithium cobalt oxide electrode, a lithium nickel cobalt manganese oxide electrode, a lithium manganese oxide electrode, a lithium iron phosphate electrode, and a lithium nickel oxide electrode, and
the negative electrode is selected from the group of a crystalline carbon electrode and amorphous carbon electrode.

11. The separator as claimed in claim 1 , wherein the separator has a thermal shrinkage of 30% or less in a machine direction or in a transverse direction, as measured after leaving the separator at 150° C. for 1 hour.

12. An electrochemical battery, comprising:
a positive electrode, a negative electrode, an electrolyte, and the separator as claimed in claim 1 .

13. The electrochemical battery as claimed in claim 12 , wherein the electrochemical battery is a lithium rechargeable battery.

14. A secondary battery, comprising:
a positive electrode;
a negative electrode;
an electrolyte; and
a separator interposed between the positive electrode and the negative electrode, the separator having a coating layer thereon, the coating layer being formed by dissolving a polyvinylidene fluoride-hexafluoropropylene copolymer having a weight average molecular weight of 800,000 g/mol or less in a first solvent to provide a first mixture, dissolving a polyvinylidene fluoride homopolymer having a weight average molecular weight of 1,000,000 g/mol or more in a second solvent to provide a second mixture, combining the first mixture and the second mixture with inorganic particles to form a coating agent, applying the coating agent to the separator, and removing the solvent from the applied coating agent so as to provide the coating layer with a residual amount of solvent of 100 ppm or less.

15. The secondary battery as claimed in claim 14 , wherein the second solvent has a boiling point of 140° C. or more.

16. The secondary battery as claimed in claim 14 , wherein the second solvent includes one or more of dimethylformamide, dimethylsulfoxide, dimethylacetamide, or N-methylpyrrolidone.

17. The secondary battery as claimed in claim 16 , wherein the removing of the solvent includes drying the separator with the coating agent thereon at a maximum temperature of 120° C. or less.

18. The separator as claimed in claim 1 , further comprising a base film on which the coating is formed, the base film being a polyethylene monolayer film having a thickness of 1 μm to 25 μm.

Assignees

• Hong Ki Chul
• Park Myung Kook
• Park Jin Kyu
• Chung Jun Ho
• Cheil Ind Inc

Inventors

• Hong Ki Chul
• Park Myung Kook
• Park Jin Kyu
• Chung Jun Ho

Classifications

• H01M50/446 Primary

  Composite material consisting of a mixture of organic and inorganic materials · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/451 Primary

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/426

  Fluorocarbon polymers · CPC title