Fuel cell stack having an integrated end plate assembly

A fuel cell stack (30) for producing electricity from reducing fluid and process oxidant reactant streams, the fuel cell stack (30) comprising:

• a. a plurality of fuel cells (32) stacked adjacent each other to form a reaction portion (34) of the fuel cell stack (30), the plurality of fuel cells (32) including an end cell (36) at an outer end of the reaction portion (34) of the fuel cell stack (30);
• b. an integrated end plate assembly (38) secured adjacent the end cell (36), the assembly including;
• i. a current collector (40) secured adjacent and in electrical communication with the end cell (36);
• ii. a pressure plate (42) secured adjacent the current collector and overlying the end cell (36), the pressure plate (42) defining a backbone-support plane (44) extending a distance from a center (46) of the pressure plate to between about thirty percent and about eighty percent of a distance between the center (46) of the pressure plate (42) and an exterior perimeter (48) of the pressure plate (42), and the pressure plate (42) defining a deflection plane (50) extending between the backbone-support plane (44) and the exterior perimeter (48) of the pressure plate (42), the deflection plane (50) also being between the backbone-support plane (44) and a contact surface (54) of the pressure plate (42) adjacent the current collector (40);
• iii. a backbone (60) including a plurality of tie-rod ends (62, 64, 66, 68) defining throughbores (70, 72, 74, 76) configured to receive and secure tie rods (78, 80) adjacent a perimeter (48) of the pressure plate (42), the backbone (60) including at least one beam (82) extending between the tie-rod ends (62, 64, 66, 68), the backbone (60) being secured adjacent the backbone-support plane (60) and configured to contact and extend along the backbone-support plane (44), and the tie-rod ends (62, 64, 66, 68) of the backbone (60) configured to overlie the deflection plane (55) and define a gap (84) between the tie-rod ends (62, 64, 66, 68) and the deflection plane (50), the backbone (60) configured to have adequate flexibility to permit expansion of the fuel cell stack (30) within operating dynamic limits of the stack (30) and having predetermined flexural strength to prohibit expansion of the stack (30) beyond the operating dynamic limits of the stack (30);
• and,
• iv. the deflection plane (55) being defined within the pressure plate (42) a predetermined distance from the backbone-support plane (44) to permit flexure of the backbone (60) within the gap (84).