Method of using graphite for making hydrophilic articles

Abstract

A water transport plate assembly that is useful in fuel cells includes at least one hydrophilic article such as a flow field layer. A method of making the hydrophilic article includes establishing a hydrophilicity of the article by including a plurality of graphite particles (112) having a particular physical characteristic that imparts the hydrophilicity to the article. In one disclosed example, the selected graphite particles (112) have a wettability ratio of a hydrophilic surface area to a total surface area that is sufficient to make the article hydrophilic. In a disclosed example, the wettability ratio is more than 0.10. In a disclosed example, the graphite particles are selected based upon a percentage of prismatic surface area of the total surface area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example water transport plate assembly including a hydrophilic structure designed according to an embodiment of this invention.

FIG. 2A schematically shows a feature of a crystal structure of an example graphite particle.

FIG. 2B schematically shows another view of the crystal structure of FIG. 2A.

FIG. 3 schematically illustrates an example manufacturing process.

FIG. 4 schematically illustrates a portion of an example article made from the example process of FIG. 3.

Claims

1. A method of making a hydrophilic article, comprising establishing a hydrophilicity of the article by including a plurality of graphite particles having a wettability ratio of a hydrophilic surface area to a total surface area that is within a range sufficient to make the article hydrophilic.

2. The method of claim 1, wherein the included plurality of graphite particles provides the only source of the hydrophilicity.

3. The method of claim 1, wherein the wettability ratio is more than about 0.10.

4. The method of claim 3, wherein the wettability ratio is more than about 0.18.

5. The method of claim 1, wherein the wettability ratio equals a ratio of a prismatic surface area to a total surface area.

6. The method of claim 1, wherein the plurality of graphite particles are generally spheroidal.

7. The method of claim 1, wherein the plurality of graphite particles comprise expanded graphite.

8. The method of claim 1, wherein the hydrophilic article comprises a plate adapted for use in a fuel cell.

9. The method of claim 1, wherein the hydrophilic article is porous.

10. A hydrophilic article made by the process, comprising establishing a hydrophilicity of the article by including a plurality of graphite particles having a wettability ratio of a hydrophilic surface area to a total surface area that is within a range sufficient to make the article hydrophilic.

11. The hydrophilic article of claim 10, wherein the included plurality of graphite particles provides the only source of the hydrophilicity.

12. The hydrophilic article of claim 10, wherein the wettability ratio is more than about 0.10.

13. The hydrophilic article of claim 12, wherein the wettability ratio is more than about 0.18.

14. The hydrophilic article of claim 10, wherein the wettability ratio equals a ratio of a prismatic surface area to a total surface area.

15. The hydrophilic article of claim 10, wherein the plurality of graphite particles are generally spheroidal.

16. The hydrophilic article of claim 10, wherein the plurality of graphite particles comprise expanded graphite.

17. The hydrophilic article of claim 10, wherein the hydrophilic article comprises a plate adapted for use in a fuel cell.

18. The hydrophilic article of claim 10, wherein the hydrophilic article is porous.

19. A method of making a hydrophilic article, comprising establishing a hydrophilicity of the article by including a plurality of graphite particles each having the at least one wettable surface establishing at least about 10% of a total surface area of each of the included plurality of the graphite particles.

20. The method of claim 19, wherein the included plurality of graphite particles each have a wettability ratio between a hydrophilic surface area and a total surface area that is more than about 0.10.

21. The method of claim 20, wherein the wettability ratio is more than about 0.18.

22. The method of claim 19, wherein the included plurality of graphite particles provide the only source of the hydrophilicity.

23. The method of claim 19, wherein the included plurality of graphite particles comprise at least one of generally spheroidal graphite particles or expanded graphite.

24. The method of claim 19, wherein the at least one wettable surface comprises a prismatic surface.

25. The method of claim 24, wherein the wettability ratio equals a ratio of a prismatic surface area to the total surface area.

26. The method of claim 19, wherein the hydrophilic article comprises a plate adapted for use in a fuel cell.

27. The method of claim 19, wherein the hydrophilic article is porous.