Carbon sheet, gas diffusion electrode substrate and fuel cell

Patent metadata

Field	Value
Publication number	US-10593956-B2
Application number	US-201515519243-A
Country	US
Kind code	B2
Filing date	Oct 7, 2015
Priority date	Oct 17, 2014
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A porous carbon sheet contains carbon fiber and a binder, wherein the carbon sheet is characterized in that in a section from a plane having a 50% filling ratio closest to one surface to a plane having a 50% filling ratio closest to the other surface, when letting layer X be a layer with the largest filling ratio close to the one surface, layer Y be a layer with a filling ratio smaller than layer X close to the other surface, and layer Z be the layer positioned between layer X and layer Y for layers obtained by dividing the carbon sheet equally into three in a direction perpendicular to the surfaces, the filling ratio for the layers becomes smaller in order of layer X, layer Y, and layer Z.

First claim

The invention claimed is:

1. A porous carbon sheet comprising a carbon fiber impregnated with a binding material, wherein, when among layers obtained by dividing the carbon sheet in a through-plane direction into three equal parts within a section extending from a surface having a 50% filling rate, which is closest to one surface, to a surface having a 50% filling rate, which is closest to the other surface, a layer which is close to the one surface and has the largest layer filling rate is a layer X, a layer which is close to the other surface and has a layer filling rate smaller than that of the layer X is a layer Y, and a layer situated between the layer X and the layer Y is a layer Z, the filling rate decreases in the order of the layer X, the layer Y and the layer Z, where the 50% filling rate is a value of 50% of an average value obtained in the following manner: the filling rate of the surface is measured every fixed length from the one surface to the other surface of the carbon sheet, and subsequently, an average value of the obtained filling rates of the surfaces is determined; and the filling rate of a layer is an average value obtained using the filling rates of the surfaces that form the layer,
wherein, when the filling rate of the layer Y is 1, the filling rate of the layer X is 1.03 or more, and the filling rate of the layer Z is 0.97 or less.

2. The carbon sheet according to claim 1 , wherein a sliding angle of water at a surface Y is 40 degrees or less where the surface Y is a surface closest to the layer Y.

3. The carbon sheet according to claim 1 , wherein the carbon sheet has a thickness of 50 μm or more and 200 μm or less.

4. The carbon sheet according to claim 1 , wherein the carbon sheet contains a hydrophobic material, and the melting point of the hydrophobic material is 200° C. or more and 320° C. or less.

5. A gas diffusion electrode substrate, wherein, when a surface closest to the layer X is a surface X, the gas diffusion electrode substrate has a microporous layer on the surface X side of the carbon sheet according to claim 1 .

6. The gas diffusion electrode substrate according to claim 5 , wherein the macroporous layer contains a carbon powder, and the carbon powder includes linear carbon having an aspect ratio of 30 to 5000.

7. A fuel cell comprising the gas diffusion electrode substrate according to claim 5 .

8. A porous carbon sheet comprising a carbon fiber impregnated with a binding material, wherein, when among layers obtained by dividing the carbon sheet in a through-plane direction into three equal parts within a section extending from a surface having a 50% filling rate, which is closest to one surface, to a surface having a 50% filling rate, which is closest to the other surface, a layer which is close to the one surface and has the largest layer filling rate is a layer X, a layer which is close to the other surface and has a layer filling rate smaller than that of the layer X is a layer Y, and a layer situated between the layer X and the layer Y is a layer Z, the filling rate decreases in the order of the layer X, the layer Y and the layer Z, where the 50% filling rate is a value of 50% of an average value obtained in the following manner: the filling rate of the surface is measured every fixed length from the one surface to the other surface of the carbon sheet, and subsequently, an average value of the obtained filling rates of the surfaces is determined; and the filling rate of a layer is an average value obtained using the fillings rates of the surfaces that foiin the layer,
wherein, when layers obtained by dividing the carbon sheet in a through-plane direction into six equal parts under compression at 0.15 MPa within a section extending from a surface to the other surface include a layer 1 , a layer 2 , a layer 3 , a layer 4 , a layer 5 and a layer 6 in this order from the layer including one surface to the layer including the other surface, a layer having the largest filling rate under compression at 0.15 MPa is the layer 2 , and
the filling rates of the layer 2 , the layer 3 , the layer 4 and the layer 5 under compression at 0.15 MPa satisfy a relationship of: filling rate of layer 2 >filling rate of layer 5 >average of filling rates of layer 3 and layer 4 ,
wherein, when the filling rate of the layer 5 is 1, the filling rate of the layer 2 is 1.03 or more, and average of the filling rates of the layer 3 and the layer 4 is 0.97 or less.

9. A porous carbon sheet comprising a carbon fiber impregnated with a binding material, wherein, when layers obtained by dividing the carbon sheet in a through-plane direction into six equal parts under compression at 0.15 MPa within a section extending from a surface to the other surface include a layer 1 , a layer 2 , a layer 3 , a layer 4 , a layer 5 and a layer 6 in this order from the layer including one surface to the layer including the other surface, a layer having a largest filling rate under compression at 0.15 MPa is the layer 2 , and
filling rates of the layer 2 , the layer 3 , the layer 4 and the layer 5 under compression at 0.15 MPa satisfy a relationship of: filling rate of layer 2 >filling rate of layer 5 >average of filling rates of layer 3 and layer 4 ,
wherein, when the filling rate of the layer 5 is 1, the filling rate of the layer 2 is 1.03 or more, and average of the filling rates of the layer 3 and the layer 4 is 0.97 or less.

10. The carbon sheet according to claim 9 , wherein a sliding angle of water at a surface 6 is 40 degrees or less where the surface 6 is a surface included in the layer 6 .

11. A gas diffusion electrode substrate, wherein, when a surface included in the layer 1 is a surface 1 , the gas diffusion electrode substrate has a microporous layer on the surface 1 side of the carbon sheet according to claim 10 .

12. A gas diffusion electrode substrate, wherein, when a surface included in the layer 1 is a surface 1 , the gas diffusion electrode substrate has a microporous layer on the surface 1 side of the carbon sheet according to claim 9 .

13. The gas diffusion electrode substrate according to claim 12 , wherein the microporous layer contains a carbon powder, and the carbon powder includes linear carbon having an aspect ratio of 30 to 5000.

14. A fuel cell comprising the gas diffusion electrode substrate according to claim 12 .

15. The carbon sheet according to claim 9 , wherein a sliding angle of water at a surface 6 is 40 degrees or less where the surface 6 is a surface included in the layer 6 .

16. A gas diffusion electrode substrate, wherein, when a surface included in the layer 1 is a surface 1 , the gas diffusion electrode substrate has a microporous layer on the surface 1 side of the carbon sheet according to claim 9 .

17. A porous carbon sheet comprising a carbon fiber impregnated with a binding material, wherein, when among layers obtained by dividing the carbon sheet in a through-plane direction into three equal parts within a section extending from a surface having a 50% filling rate, which is closest to one surface, to a surface having a 50% filling rate, which is closest to the other surface, a layer which is close to the one surface and has the largest layer filling rate is a layer X, a layer which is close to the other surface and has a layer filling rate smaller than that of the layer X is a layer Y, and a layer situated between the layer X and the layer Y is a layer Z, the filling rate decreases in the order of the layer X, the layer Y and the layer Z, where the 50% filling rate is

Assignees

• Toray Industries

Inventors

• Sode Katsuya
• Chida Takashi
• Utsunomiya Masamichi
• Sugahara Toru
• Ando Takashi

Classifications

• H01M4/881

  Electrolytic membranes · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M4/8807 Primary

  Gas diffusion layers · CPC title

• H01M4/96

  Carbon-based electrodes · CPC title

• H01M4/8605

  Porous electrodes · CPC title