Binder composition, separator including binder formed from the binder composition, lithium battery including the separator, and method of preparing the binder composition

Patent metadata

Field	Value
Publication number	US-9634309-B2
Application number	US-201414516004-A
Country	US
Kind code	B2
Filing date	Oct 16, 2014
Priority date	Dec 2, 2013
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A separator for a battery, a battery, and a method of preparing a graft copolymer for a binder, the separator including a porous substrate; a coating layer on at least one surface of the porous substrate, the coating layer including an inorganic oxide; and a binder between the porous substrate and the inorganic oxide or between adjacent particles of the inorganic oxide, the binder including a graft copolymer, wherein the graft copolymer has a backbone of a polyvinylidene fluoride-based polymer or a polyvinylidene fluoride-based copolymer, and a pendant chain grafted to the backbone, the pendant chain including a hydrophilic repeating unit, and fluorine atoms in the backbone of the graft copolymer are partially substituted with at least one of chlorine, bromine, or iodine.

First claim

What is claimed is:

1. A separator for a battery, the separator comprising:
a porous substrate;
a coating layer on at least one surface of the porous substrate, the coating layer including an inorganic oxide; and
a binder between the porous substrate and the inorganic oxide or between adjacent particles of the inorganic oxide, the binder including a graft copolymer, wherein:
the graft copolymer has:
a backbone of a polyvinylidene fluoride-based polymer or a polyvinylidene fluoride-based copolymer, and
a pendant chain grafted to the backbone, the pendant chain including a hydrophilic repeating unit, and

fluorine atoms in the backbone of the graft copolymer are partially substituted with at least one of chlorine, bromine, or iodine.

2. The separator as claimed in claim 1 , wherein an amount of the fluorine atoms partially substituted with the at least one of chlorine, bromine, or iodine is about 1 wt % to about 10 wt %, based on a total weight of fluorine atoms in the backbone.

3. The separator as claimed in claim 1 , wherein the backbone includes polyvinylidene fluoride-co-chlorotrifluoroethylene or polyvinylidene fluoride-co-chlorotrifluoroethylene/polyvinylidene fluoride-co-hexafluoropropylene.

4. The separator as claimed in claim 1 , wherein the pendant chain has a weight average molecular weight of from about 100 g/mol to about 1,000,000 g/mol.

5. The separator as claimed in claim 1 , wherein the pendant chain includes a carboxyl group in the hydrophilic repeating unit.

6. The separator as claimed in claim 1 , wherein the hydrophilic repeating unit is derived from a vinyl-based monomer.

7. The separator as claimed in claim 6 , wherein the vinyl-based monomer includes at least one of acrylic acid, butyl acrylate, triethylene glycol acrylate, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, maleic anhydride, ethylene glycol vinyl ether, or itaconic acid.

8. The separator as claimed in claim 1 , wherein the graft copolymer is included in the binder in an amount of about 0.1 wt % to about 100 wt %, based on a total weight of the binder.

9. The separator as claimed in claim 1 , wherein the inorganic oxide includes at least one selected from α-Al 2 O 3 , γ-Al(O)OH, TiO 2 , ZrO 2 , and SiO 2 .

10. The separator as claimed in claim 1 , wherein the binder is included in the separator in an amount of about 1 wt % to about 50 wt %, based on a total weight of the inorganic oxide.

11. The separator as claimed in claim 1 , wherein the porous substrate is a polyolefin-based porous substrate.

12. The separator as claimed in claim 1 , wherein the binder has an adhesive strength of about 40 mN/mm or greater with respect to the porous substrate.

13. A battery, comprising:
a cathode;
an anode; and
a separator between the cathode and the anode, the separator being the separator as claimed in claim 1 .

Assignees

• Samsung Sdi Co Ltd

Inventors

• Park June
• Endo Takahiro
• Nam Jung-Hyun
• Park Jong-Hwan
• Fukuchi Iwao

Classifications

• H01M50/451

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

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M10/052

  Li-accumulators · CPC title

• C08F259/08 Primary

  on to polymers containing fluorine · CPC title

• C08J7/0423

  with at least one layer of inorganic material and at least one layer of a composition containing a polymer binder · CPC title