Ion exchange membrane suitable for redox flow battery

Patent metadata

Field	Value
Publication number	US-12021284-B2
Application number	US-202016865576-A
Country	US
Kind code	B2
Filing date	May 4, 2020
Priority date	Nov 6, 2017
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

The present invention provides an ion exchange membrane can improve the current efficiency of a redox flow battery without a drop in voltage efficiency, when used in the redox flow battery. The ion exchange membrane of the present invention is an ion exchange membrane comprising a fluorinated polymer having sulfonic acid functional groups, wherein the difference (D−Dc) between the distance D between ionic clusters and the diameter Dc of ionic clusters as measured by the small angle X-ray scattering is 0.60 nm or more, and the ion exchange capacity of the fluorinated polymer is 0.95 meq/gram dry resin or more.

First claim

What is claimed is:

1. A redox flow battery, comprising an ion exchange membrane comprising a fluorinated polymer having sulfonic acid functional groups, wherein a diameter Dc of ionic clusters is from 3.53 to 4.40 nm, the distance D between ionic clusters is from 4.25 to 5.00 nm, the difference (D-Dc) between the distance D between ionic clusters and the diameter De of ionic clusters as measured by small angle X-ray scattering is at least 0.60 nm, and the ion exchange capacity of the fluorinated polymer is at least 0.95 meq/g dry resin.

2. The redox flow battery according to claim 1 , wherein the difference (D−Dc) between the distance D between ionic clusters and the diameter De of ionic clusters is at least 0.70 nm.

3. The redox flow battery according to claim 1 , wherein the ion exchange capacity of the fluorinated polymer is from 1.00 to 1.10 meq/g dry resin.

4. The redox flow battery according to claim 1 , which is from 30 to 500 μm in thickness.

5. The redox flow battery according to claim 1 , wherein the fluorinated polymer comprises units based on a fluoroolefin and units based on a fluorine-containing monomer having a sulfonic acid functional group.

6. The redox flow battery according to claim 5 , wherein the units based on a fluoroolefin are based on tetrafluoroethylene.

7. The redox flow battery according to claim 5 , wherein the units based on a fluorine-containing monomer having a sulfonic acid functional group are represented by the formula (1):
—[CF 2 —CF(-L-(SO 3 M) n )]—  Formula (1):

wherein L is a (n+1)-valent perfluorinated hydrocarbon group which may contain an oxygen atom, M is a hydrogen atom, an alkali metal or a quaternary ammonium cation, and n is 1 or 2.

8. The redox flow battery according to claim 7 , wherein the units represented by the formula (1) are units represented by the formula (1-4):
—[CF 2 —CF 2 —(CF 2 ) x —(OCF 2 CFY) y —O—(CF 2 ) z —SO 3 M)]—  Formula (1-4):

wherein M is a hydrogen atom, an alkali metal or a quaternary ammonium cation, x is 0 or 1, y is an integer of 0 to 2, z is an integer of 1 to 4, and Y is F or CF 3 .

9. The redox flow battery according to claim 1 , which has a reinforcing material inside.

10. The redox flow battery according to claim 1 , wherein the ion exchange membrane does not contain a polymer other than the fluorinated polymer having sulfonic acid functional groups, and the fluorinated polymer having sulfonic acid functional groups consists of units based on a fluoroolefin and units based on a fluorine-containing monomer having a sulfonic acid functional group.

Assignees

• Agc Inc

Inventors

• Yamaki Yasushi
• Sumikura Kosuke
• Miyajima Tatsuya
• Nishio Takuo

Classifications

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/1023

  having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title

• C08J5/2237

  containing fluorine · CPC title