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).
Abstract:
A stack (10) of fuel cells (11) is provided 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) defined 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 2.0 millimeters (2 and 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).
Abstract:
A method of manufacturing a flow field plate includes mixing graphite and resin materials to provide a mixture. The mixture is formed into a continuous flow field plate, for example, by ram extrusion or one or more press belts. The continuous flow field plate is separated into discrete flow field plates. Flow field channels are provided in one of the continuous flow field plate and the discrete flow field plates.
Abstract:
A composite plate (26) is formed in a mold (8) by placing one of two preforms (15, 23) of between about 80 wt.% and about 85 wt.% flake graphite, balance polymer binder, into the mold and disposing a coolant tube array (18) thereon, depositing a powder (21) of the flake/polymer around the tube array, placing a second preform on the powder and a mold plunger (27) on the second preform, heating the mold to the melting temperature of the polymer under a pressure of 625 psi (4311 kPa), cooling the mold to the solidification temperature of the polymer while still under pressure, cooling the mold further, disassembling the mold, and removing the composite plate. The composite plate has reactant gas flow field channels (31, 32) in major surfaces thereof, is devoid of any acid edge protection layer or film and is devoid of any acid impervious separator plate between either of the fuel cell reactant gas flow fields and the coolant tube array.
Abstract:
A fuel cell separator plate assembly (20, 20a) includes a separator layer (22, 22a) and one or more reactant flow field layers (24, 24a, 26, 26a) comprising graphite flakes and a thermoplastic, hydrophobic resin which secures flow field layers on opposite sides of the separator layer. In another example, a separator plate assembly (20a) comprises a monolithic structure in which the separator portion (22a) and the flow field portions (24a, 26a) are all formed in a single piece of the same material. A method heats thermoplastic resin to its point of complete melting, then cools to its point where melting begins, increasing both electric and thermal conductivity. Methods include bonding under higher pressure than previously used, about 800 psi, or under pressures about 750 psi.