Carbon sheet as well as gas diffusion electrode substrate, membrane electrode assembly, and fuel cell using same

Patent metadata

Field	Value
Publication number	US-2026031367-A1
Application number	US-202318849874-A
Country	US
Kind code	A1
Filing date	Mar 24, 2023
Priority date	Mar 30, 2022
Publication date	Jan 29, 2026
Grant date	—

Abstract

This carbon sheet includes at least a carbon fiber structure formed from carbon fibers, a binding agent, and graphite particles, wherein in a pore diameter distribution of the carbon sheet, the ratio of the volume of a second peak present in a region having a pore diameter of 0.5 μm to 3 μm to the volume of a first peak present in a region having a pore diameter of 20 μm to 100 μm is 0.06 to 0.50. A carbon sheet which suppresses dry-up and achieves both conductivity and retention of moisture is provided in order to exhibit high power generation performance in a solid polymer fuel cell.

First claim

1 . A carbon sheet comprising at least a carbon fiber structure formed from carbon fibers, a binding agent, and graphite particles, wherein
in a pore diameter distribution of the carbon sheet, a ratio of a volume of a second peak present in a region of a pore diameter of 0.5 μm or more and 3 μm or less to a volume of a first peak present in a region of 20 μm or more and 100 μm or less is 0.06 to 0.50.

2 . The carbon sheet according to claim 1 , wherein the carbon fiber structure is a carbon fiber paper material.

3 . The carbon sheet according to claim 1 , wherein the graphite particles have an aspect ratio of 5 or more.

4 . The carbon sheet according to claim 1 , wherein the graphite particles have an average particle size of 1 μm or more and 20 μm or less.

5 . The carbon sheet according to claim 1 , wherein the graphite particles are vein graphite or scale-like graphite.

6 . The carbon sheet according to claim 1 , wherein a mass of the graphite particles is 30 mass % or more and 50 mass % or less in a mass of the entire carbon sheet.

7 . The carbon sheet according to claim 1 , wherein a mass of the graphite particles is 100 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the binding agent.

8 . The carbon sheet according to claim 1 , having a conductive resistance in a through-plane direction of 0.5 mΩ·cm 2 or more and 4.5 mΩ·cm 2 or less when pressurized at 1.0 MPa.

9 . The carbon sheet according to claim 1 , having a thermal resistance in a through-plane direction of 0.5 K·cm 2 /W or more and 3.3 K·cm 2 /W or less when pressurized at 1.0 MPa.

10 . A water repellent carbon sheet comprising the carbon sheet according to claim 1 and further comprising a water repellent material.

11 . A gas diffusion electrode substrate comprising a microporous layer on one surface of the carbon sheet according to claim 1 .

12 . A membrane electrode assembly comprising the carbon sheet according to claim 1 as a gas diffusion electrode, wherein the gas diffusion electrode is bonded to at least one surface of a solid polymer electrolyte membrane provided with a catalyst layer on both surfaces.

13 . A membrane electrode assembly comprising the carbon sheet according to claim 1 as a cathode-side gas diffusion electrode; and a gas diffusion electrode having a higher thermal resistance than that of the cathode-side gas diffusion electrode on an anode side, wherein the gas diffusion electrode is bonded to a solid polymer electrolyte membrane provided with a catalyst layer on both surfaces.

14 . A fuel cell comprising bipolar plates on both sides of the membrane electrode assembly according to claim 12 .

15 . A fuel cell comprising bipolar plates on both sides of the membrane electrode assembly according to claim 13 .

16 . Transportation equipment using the fuel cell according to claim 14 as a power source.

17 . Transportation equipment using the fuel cell according to claim 15 as a power source.

18 . A method for producing a carbon sheet to produce the carbon sheet according to claim 1 , comprising impregnating a carbon fiber structure with a liquid composition containing a mixture of a thermosetting resin and a thermoplastic resin and the graphite particles.

19 . The method for producing a carbon sheet according to claim 18 , comprising heat-treating the carbon fiber structure impregnated with the liquid composition containing the mixture of the thermosetting resin and the thermoplastic resin in an inert atmosphere at 1,300° C. or more and 3,000° C. or less.

Assignees

• Toray Industries

Inventors

• Otake Hiroaki
• Utsunomiya Masamichi
• Watanabe Fumitaka
• Sode Katsuya

Classifications

• H01M2250/20

  Fuel cells in motive systems, e.g. vehicle, ship, plane · CPC title

• D10B2505/00

  Industrial · CPC title

• D10B2101/12

  Carbon; Pitch · CPC title

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• H01M8/0245

  in the form of layered or coated products · CPC title