MANUFACTURE OF A FUEL CELL WITH LIQUID ELECTROLYTE MIGRATION PREVENTION

• US 20120028172A1
• Filed: 06/18/2009
• Published: 02/02/2012
• Est. Priority Date: 04/20/2009
• Status: Active Grant

• Current Assignee: Hyaxiom Incorporated (Doosan Corporation)
• Original Assignee: Doosan Fuel Cell America, Inc. (Doosan Corporation)
• Inventors: Kanuri, Sridhar V., Breault, Richard D., Cipollini, Ned E., Tenneti, Kishore Kumar, Kenney, Frank E.
• Granted Patent: US 10,170,783 B2
• Time in Patent Office: Days
• US Class Current: 429/535
• CPC Class Codes: H01M 8/0228 in the form of layered or coated products
• CPC Class Codes: H01M 8/0284 Organic resins; Organic polymers
• CPC Class Codes: H01M 8/0286 Processes for forming seals
• CPC Class Codes: H01M 8/086 Phosphoric acid fuel cells [PAFC]
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A stack (10) of fuel cells (11) is manufactured with barriers (32) to prevent migration of a liquid electrolyte (such as phosphoric acid) out of the cells (11). The barrier (32) is secured within a step (34) formed within a land region (28) of a separator plate assembly (18) and extends from an edge (30) of the separator plate assembly (18) all or a portion of a distance between the edge (30) and a flow channel (24) defined within the separator plate assembly (18). The barrier (32) also extends away from the edge (30) a distance of between 0.051 and about 2.0 millimeters (about 2 and about 80 mils. The barrier (32) includes a hydrophobic, polymeric film (36), a pressure sensitive adhesive (38) as an assembly aid, and a fluoroelastomer bonding agent (40).

Claims

1. A method characterized by:

manufacturing a stack (10) of liquid acid fuel cells (11) having a barrier (32) configured to prevent migration of acid between the fuel cells (11), said method comprising the steps of;

a. securing a barrier (32) to a land region (28) of a separator plate assembly (18) of the fuel cell, wherein the land region (28) extends from an edge (30) of the assembly (18) all or a portion of a distance between the edge (30) and an adjacent flow channel (24) defined within the separator plate assembly (18);

b. securing the barrier (32) to acid migration (34) adjacent the land region (28) so that the barrier (32) is configured to extend across at least a portion of the land region (28) and to extend away from the adjacent edge (30) of the separator plate assembly (18) in a direction away from the flow channel (24); and

c. securing the separator plate assembly (18) adjacent an electrode (12, 14) of the fuel cell (11) so that the flow channel (24) is adjacent the electrode (12, 14).

2. A method according to claim 1 further characterized in that:

said step b. comprises securing a hydrophobic film (36) which extends away from the adjacent edge (30) of the separator plate (18) between about 0.051 and about 2.0 millimeters (about 2 and about 80 mils).

3. A method according to claim 1 further characterized in that:

said step b. comprises securing a hydrophobic film (36) which is between about 0.05 mm and 0.127 mm (about 2 mils and about 5 mils thick).

4. A method according to claim 1 further characterized in that:

said step b. comprises securing a barrier of hydrophobic polymer film (36).

5. A method according to claim 4 further characterized in that:

said hydrophobic polymer film (36) is selected from polytetrafluroethylene, fluorinated ethylene propylene and polyfluoroaloxy copolymer resin.

6. A method according to claim 1 further characterized in that:

said steps a. and b. comprise defining a step (34) within the land region (28) of the separator plate assembly (18).

7. A method according to claim 1 further characterized in that:

said steps a. and b. comprise defining a step (34) within the land region (28) of the separator plate assembly (18) and securing a barrier (32) within the step (34) which step (34) and barrier (32) extend all of the distance between the adjacent edge (30) and the flow channel (24).

8. A method according to claim 1 further characterized in that:

said steps a. and b. comprise defining a step (34) within the land region (28) of the separator plate assembly (18) and securing a barrier (32) within the step (34) which step (34) and barrier (32) extend only a portion of the distance between the adjacent edge (30) and the flow channel (24).

9. A method according to claim 6 further characterized in that:

said step b. comprises bonding the barrier (32) to the step (34).

10. A method according to claim 6 further characterized in that:

said step b. comprises bonding the barrier (32) to the step (34) with a fluoroelastomer.

11. A method according to claim 10 further characterized in that:

said step b. comprises bonding the barrier (32) to the step (34) with a fluoroelastomer having a fluorine content greater than about 68% by weight.

12. A method according to claim 9 further characterized in that:

the bond is created during the manufacturing process, prior to assembly of fuel cells (11) into the stack (10).

13. A method according to claim 9 further characterized in that:

the bond is created in situ within a fuel cell stack (10) during initial heating up of the stack.

14. A method according to claim 4, characterized by:

coating the hydrophobic polymer film (36) with pressure sensitive adhesive (38) on the surface of the polymer film (36) which is to contact the step (34), prior to securing the polymer film (36) within the step (34).

15. A method according to claim 14 further characterized in that:

the pressure sensitive adhesive (38) is selected from an acrylic adhesive and a silicone adhesive.

16. A method according to claim 6 further characterized in that:

said steps a. and b. comprise defining a step (34) and securing a barrier (32) only in land regions (28) adjacent ones of said flow channels (24) which direct the oxygen-containing oxidant reactant stream.

17. A method according to claim 6 further characterized in that:

said steps a. and b. comprise defining a step (34) and securing a barrier (32) only in land regions (28) adjacent ones of said flow channels (24) which direct the hydrogen-containing reducing fluid fuel stream.

18. A method according to claim 6 further characterized in that:

said steps a. and b. comprise defining a step (34) and securing a barrier (32) only in land regions (28) adjacent edges (30) of said separator plate assembly (18) through which the oxygen-containing oxidant reactant stream enters the related flow channel (24).

19. A method according to claim 6 further characterized in that:

said steps a. and b. comprise defining a step (34) and securing a barrier (32) in land regions (28) adjacent edges (30) of said separator plate assembly (18) through which the oxygen-containing oxidant reactant stream enters the related flow channel (24), and in land regions (28) adjacent edges (30) of said separator plate assembly (18) through which the oxygen-containing oxidant reactant stream exits the flow channel (24).

20. A method according to claim 6, characterized by:

a. defining a second step (34) within a second land region (28) of the separator plate assembly (18) extending from a second edge (30) of the assembly (18) all or a portion of a distance between the second edge (30) and a second flow channel (24); and

b. securing a second barrier (32) to acid migration within the step (34), said barrier configured to extend across the step (34) and to extend away from the second edge (30) of the separator plate assembly (18) in a direction away from the second flow channel (24).

21. A method according to claim 6 further characterized by:

securing a barrier of hydrophobic polymer film (36) to the step (34) while compressing the hydrophobic polymer film (36) toward the adjacent land region (28).

22. A method according to claim 22 further characterized by:

compressing the hydrophobic polymer film (36) toward the adjacent land region (28) by an axial force of at least 345 kPa (50 psi).

23. A method according to step 8 further characterized by:

defining the step (34) so that a depth of the step (34) below the land region (28) of the separator plate assembly (18) is about equal to a thickness of the barrier (32).

24. A method according to step 8 further characterized by:

defining the step (34) so that a depth of the step (34) below the land region (28) of the separator plate assembly (18) is between about 80% and about 120% of a thickness of the barrier (32).