Fuel cell electrolyte management device

1. A fuel cell electrolyte management device, comprising:

a first component having a first density, the first component having a first side including a pocket and a second side facing opposite the first side, the second side including a first plurality of fluid flow channels; and

a second component having a second density that is lower than the first density, the second component having a porosity configured for storing electrolyte in the second component, the second component fitting within the pocket, the second component having a first side received directly against the first side of the first component, the second component having a second side including a second plurality of fluid flow channels.

2. The device of claim 1 , wherein

the first component comprises a first type of graphite and a first type of resin; and

the second component comprises a second type of graphite that is different from the first type of graphite and a second type of resin that is different from the first type or resin.

3. The device of claim 2 , wherein

the first type of graphite comprises at least graphite flakes; and

the second type of graphite comprises at least non-flake graphite.

4. The device of claim 2 , wherein

the first resin comprises a fluoropolymer resin; and

the second resin comprises a thermosetting polymeric resin.

5. The device of claim 4 , wherein the fluoropolymer resin is between 10% and 50% by weight of the first component.

6. The device of claim 1 , wherein the second component is at least temporarily bonded to the pocket by an adhesive that decomposes at a temperature above an ambient or room temperature.

7. The device of claim 1 , wherein the second component is at least temporarily bonded to the pocket by an adhesive that is situated along a border of the pocket.

8. The device of claim 6 , wherein the first density is at least 2 gm/cm 3 .

9. The device of claim 1 , wherein the first density is effective as a barrier to prevent electrolyte migration through the first component.

10. The device of claim 1 , wherein

the device has a through plane electrical resistivity that is less than 0.0017 mVmill at approximately 100 psi axial load and 100 ASF; and

a through plane thermal conductivity that is greater than 7 W/mK and less than 12 W/mK at approximately 140 psi.

11. The device of claim 1 , wherein the second component is between 30% and 75% porous.

12. The device of claim 1 , wherein pores of the second component have a size between 3 microns and 20 microns.

13. The device of claim 1 , wherein

the first component includes a rib on each of at least two edges of the pocket;

the ribs have a height;

the second component has a thickness in a direction between the first and second sides of the second component; and

the height is approximately equal to the thickness.

14. The device of claim 1 , wherein

the first component includes a rib on each of two edges of the pocket;

the ribs are parallel to the second plurality of fluid flow channels; and

a seal member is situated on each of the ribs.

15. The device of claim 14 , wherein each seal member includes a flap portion extending laterally outward beyond an edge of the corresponding rib.

16. The device of claim 14 , wherein

the first plurality of fluid flow channels are generally perpendicular to the ribs;

a first component seal member is situated on each laterally outermost edge of the second side of the first component; and

the first component seal members are parallel to the first plurality of fluid flow channels.

17. A method of making a fuel cell electrolyte management device, the method comprising:

forming a first component from a first mixture comprising a first type of graphite and a first resin, the first component having a first density;

providing the first component with a pocket on a first side of the first component;

forming a second component from a second mixture comprising a second type of graphite and a second resin, the second component having a second density that is less than the first density, the second component having a porosity that is configured to store electrolyte in the second component;

situating the second component in the pocket with a first side of the second component received directly against the first side of the first component; and

providing fluid flow channels on each of the first component and the second component.

18. The method of claim 17 , wherein

forming the first component comprises

pressing the first mixture into a first preform using a pressure of 4000 psi at ambient temperature;

subsequently pressing the preform using a pressure of 800 psi at a temperature of 550° F. for about an hour;

subsequently pressing the preform using a pressure of 800 psi at a temperature of 140° F. for about an hour; and

forming the second component comprises

pressing the second mixture into a second preform using a pressure of 200 psi at 180° C. for about 30 minutes; and

subsequently converting the second resin to carbon by heating the second preform at a temperature of about 900° C. while the second preform is exposed to an inert gas.

19. The method of claim 17 , wherein

providing the first component with the pocket comprises at least one of

machining a portion of the first component away to establish the pocket; or

forming the pocket during the forming of the first component.

20. The method of claim 17 , wherein

the first density is at least 2 gm/cm 3 ; and

the second component is between 30% and 75% porous.

21. The method of claim 17 , comprising

at least temporarily bonding the second component to the pocket by an adhesive that decomposes at a temperature above an ambient or room temperature.

22. The method of claim 17 , comprising

placing an adhesive along a border of the pocket; and

at least temporarily bonding the second component to the pocket using the adhesive.

23. The method of claim 17 , wherein

the second mixture comprises a wax that vaporizes at an elevated temperature; and

the second component has pores in locations occupied by the wax prior to the wax vaporizing.

24. The method of claim 17 , wherein

the device has a through plane electrical resistivity that is less than 0.0017 mVmill at 100 psi axial load and 100 ASF; and

a through plane thermal conductivity that is greater than 7 W/mK and less than 12 W/mK at approximately 140 psi.

25. The method of claim 17 , wherein

the first mixture comprises about 85% flake graphite and about 15% fluoropolymer resin by mass; and

the second mixture comprises about 80% non-flake graphite and about 20% thermosetting polymeric resin by mass.