Gas diffusion electrode medium and method for producing the same, gas diffusion electrode, membrane electrode assembly, and polymer electrolyte fuel cell

Patent metadata

Field	Value
Publication number	US-2022200012-A1
Application number	US-202017602054-A
Country	US
Kind code	A1
Filing date	Mar 16, 2020
Priority date	Apr 19, 2019
Publication date	Jun 23, 2022
Grant date	—

Abstract

In order to provide a gas diffusion electrode medium having high thermal conductivity despite having low density and excellent both in handleability and cell performance, provided is a gas diffusion electrode medium including carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 μm, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm2.

First claim

1 . A gas diffusion electrode medium comprising carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 μm, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm 2 .

2 . The gas diffusion electrode medium according to claim 1 , wherein the carbon fiber felt contains graphite.

3 . The gas diffusion electrode medium according to claim 1 , having a thermal conductivity of 0.25 to 10 W/(m·K).

4 . The gas diffusion electrode medium according to claim 1 , having a density of 0.3 to 0.8 g/cm 3 .

5 . The gas diffusion electrode medium according to claim 1 , comprising a microporous layer provided on one surface of the carbon fiber felt, wherein the carbon fibers having the flat parts are observed in a plane view of another surface of the carbon fiber felt.

6 . The gas diffusion electrode medium according to claim 5 , having a fluorine/carbon element ratio of 0.10 to 0.15 at a surface of the gas diffusion electrode medium on a microporous layer side, and a fluorine/carbon element ratio of less than 0.10 at another surface of the gas diffusion electrode medium.

7 . The gas diffusion electrode medium according to claim 5 , wherein a surface of the microporous layer has a glossiness of 31 degrees or more.

8 . A method for producing a gas diffusion electrode medium, the method comprising:
step A: a step of entangling, by water flow, flame resistant fibers having a specific gravity of 1.30 to 1.36 g/cm 3 and a fineness of 0.5 to 2.2 dtex to produce flame resistant fiber felt having a moisture content of 20 to 60%; step B: a step of heating and pressurizing the flame resistant fiber felt obtained in step A at a surface pressure of 2 to 10 MPa and at 240 to 300° C.; and step C: a step of carbonizing the flame resistant fiber felt pressurized in step B to produce carbon fiber felt.

9 . The production method according to claim 8 , wherein in step B, the pressurization is performed by calendering.

10 . The production method according to claim 8 , wherein in step C, a heating temperature in the carbonization is 2000° C. or less.

11 . The production method according to claim 8 , further comprising:
step D: a step of forming a microporous layer on one surface of the carbon fiber felt after step C.

12 . The production method according to claim 11 , further comprising:
step E: a step of performing calendering after step D.

13 . A gas diffusion electrode comprising:
the gas diffusion electrode medium according to claim 1 ; and a catalyst layer provided on a surface of the gas diffusion electrode medium.

14 . A membrane electrode assembly comprising:
a polymer electrolyte membrane; a catalyst layer; and the gas diffusion electrode medium according to claim 1 .

15 . A polymer electrolyte fuel cell comprising the membrane electrode assembly according to claim 14 .

Assignees

• Toray Industries

Inventors

• Utsunomiya Masamichi
• Shimoyama Satoru
• Watanabe Fumitaka

Classifications

• Y02E60/50

  Fuel cells · CPC title

• H01M8/1018 Primary

  Polymeric electrolyte materials · CPC title

• D04H1/54

  by welding together the fibres, e.g. by partially melting or dissolving (in combination with needling D04H1/485) · CPC title

• H01M4/8896

  Pressing, rolling, calendering (membrane electrode assemblies H01M8/1004) · CPC title

• H01M4/92

  Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence) · CPC title