Polymer electrolyte membrane and method for producing the same

Patent metadata

Field	Value
Publication number	US-11539064-B2
Application number	US-201716330633-A
Country	US
Kind code	B2
Filing date	Sep 7, 2017
Priority date	Sep 8, 2016
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

A polymer electrolyte membrane according to the present invention has a cluster diameter of 2.96 to 4.00 nm and a converted puncture strength of 300 gf/50 μm or more. The polymer electrolyte membrane according to the present invention has a low electric resistance and an excellent mechanical strength.

First claim

The invention claimed is:

1. A polymer electrolyte membrane, having an ion cluster diameter of 3.02 nm to 3.17 nm and a converted puncture strength of 300 gf/50 μm or more, comprising:
a mixture of two or more fluorine-based electrolyte polymers, each of which has an ion-exchange group and has a monomer structure different from each other, wherein
the fluorine-based electrolyte polymers are PFSA resins having structures represented by the following formula (5); and
the PFSA resins are obtained by hydrolyzing a PFSA resin precursor composed of a copolymer of a fluorinated vinyl ether compound represented by the following formula (6) with a fluoroolefin monomer represented by the following formula (8),
—[CF 2 CF 2 ] a —[CF 2 —CF(—O—(CF 2 ) m —SO 3 H)] g —  (5)

wherein 0 a≤1, 0<g≤1, and a+g=1; and m is an integer of 1 to 6,
CF 2 ═CF—O—(CF 2 CFXO) n -A  (6)

wherein X is F or a perfluoroalkyl group having 1 to 3 carbon atoms; n is an integer of 0 to 5; and A is (CF 2 ) m -W, wherein m is an integer of 0 to 6, n and m are not 0 at the same time, and W is a functional group convertible to SO 3 H by hydrolysis,
CF2=CFZ  (8)

wherein Z is H, Cl, F, a perfluoroalkyl group having 1 to 3 carbon atoms, or a cyclic perfluoroalkyl group which may contain oxygen, and
wherein the polymer electrolyte membrane has an equivalent weight, EW, of 700 to 950 (g/eq); wherein the ion cluster diameter is measured after immersion for 24 hours in water at 25° C. by small angle X-ray scattering.

2. The polymer electrolyte membrane according to claim 1 , having an ion conductivity of 0.10 S/cm or more.

3. A method for producing the polymer electrolyte membrane of claim 1 , comprising:
a) mixing two or more fluorine-based electrolyte polymers, each of which has an ion-exchange group and has a monomer structure different from each other, wherein the fluorine-based electrolyte polymers are PFSA resins having structures represented by the following formula (5); and
the PFSA resins are obtained by hydrolyzing a PFSA resin precursor composed of a copolymer of a fluorinated vinyl ether compound represented by the following formula (6) with a fluoroolefin monomer represented by the following formula (8),
—[CF 2 CF 2 ] a —[CF 2 —CF(—O—(CF 2 ) m —SO 3 H)] g —  (5)

wherein 0 a≤1, 0<g≤1, and a+g=1; and m is an integer of 1 to 6,
CF 2 ═CF—O—(CF 2 CFXO) n -A  (6)

wherein X is F or a perfluoroalkyl group having 1 to 3 carbon atoms; n is an integer of 0 to 5; and A is (CF 2 ) m -W, wherein m is an integer of 0 to 6, n and m are not 0 at the same time, and W is a functional group convertible to SO 3 H by hydrolysis,
CF2=CFZ  (8)

wherein Z is H, Cl, F, a perfluoroalkyl group having 1 to 3 carbon atoms, or a cyclic perfluoroalkyl group which may contain oxygen, and
wherein the polymer electrolyte membrane has an equivalent weight, EW, of 700 to 950 (g/eq);
b) casting the polymer electrolyte membrane from a suspension or a solution of the mixed fluorine-based electrolyte polymers; and
c) subjecting the cast polymer electrolyte membrane to a heat treatment at a temperature of more than 210° C.

4. The method for producing the polymer electrolyte membrane according to claim 3 , wherein the temperature of the heat treatment is 215° C. or more.

5. A redox flow secondary battery, comprising the polymer electrolyte membrane according to claim 1 .

6. A water electrolysis facility, comprising the polymer electrolyte membrane according to claim 1 .

7. A membrane electrode assembly, comprising the polymer electrolyte membrane according to claim 1 .

8. A fuel cell, comprising the membrane electrode assembly according to claim 7 .

Assignees

• Asahi Chemical Ind

Inventors

• Inoue Yuichi
• Ishii Takumi

Classifications

• H01M8/188

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

• H01M8/1039

  halogenated, e.g. sulfonated polyvinylidene fluorides · CPC title

• H01M8/1044 Primary

  Mixtures of polymers, of which at least one is ionically conductive · CPC title

• H01B1/122

  Ionic conductors · CPC title

• H01M8/1067

  characterised by their physical properties, e.g. porosity, ionic conductivity or thickness · CPC title