摘要:
A process for making dry carbon/polytetrafluoroethylene floc material, particularly useful in the manufacture of fuel cell electrodes, comprises of the steps of floccing a co-suspension of carbon particles and polytetrafluoroethylene particles, filtering excess liquids from the co-suspension, molding pellet shapes from the remaining wet floc solids without using significant pressure during the molding, drying the wet floc pellet shapes within the mold at temperatures no greater than about 150.degree. F., and removing the dry pellets from the mold.
摘要:
A novel method for making an electrode for use in an electrochemical cell comprises forming a substrate by coating the fibers of a fibrous carbon paper with pyrolytic carbon, wet proofing the coated paper with a hydrophobic polymer, sintering the wet proofed paper, and applying a catalyst/hydrophobic polymer layer thereon.
摘要:
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.
摘要:
A fuel cell assembly (20) has an extended operational life, in part, because of unique startup and shutdown procedures used for operating the fuel cell assembly. In disclosed examples, a purge gas mixture of hydrogen and nitrogen includes less than 2% hydrogen for selectively purging portions of the assembly during a startup or shutdown procedure. In a disclosed example, the hydrogen-nitrogen mixture contains less than 0.1% hydrogen.
摘要:
A method of making an electrochemical cell electrode substrate includes creating an aqueous or dry mixture of chopped carbon fibers, chopped cross-linkable resin fibers that are still fuseable after being formed into a felt, such as novolac, a temporary binder, such as polyvinyl alcohol fiber or powder, forming a non-woven felt from either an aqueous suspension of the aqueous mixture or an air suspension of the dry mixture, by a non-woven, wet-lay or dry-lay, respectively, felt forming process, a resin curing agent, such as hexamethylene tetramine may be included in the aqueous or dry mixture, or it may be coated onto the formed felt; pressing one or more layers of the formed felt for 1-5 minutes to a controlled thickness and a controlled porosity at a temperature at which the resin melts, cross-links and then cures, such as 150° C.-200° C.; and heat treating the pressed felt in a substantially inert atmosphere, first to 750° C.-1000° C. and then to 1000° C.-3000° C.
摘要:
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).
摘要:
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.
摘要:
An electrode substrate is disclosed that includes a plane and a through-plane direction. First and second carbon fibers are respectively arranged in the plane and through-plane direction. The substrate includes a thickness in the through-plane direction and the second fiber has a length less than the thickness. The first carbon fiber has a length greater than the thickness. In one example method of manufacturing the example substrate, PAN-based carbon fibers are blended with meso-phase pitch-based carbon fibers. A resin is applied to a non-woven felt constructed from the carbon fibers. The felt and resin are heated to a desired temperature to achieve a desired through-plane thermal conductivity.
摘要:
A fuel cell (8a) having a matrix (11) for containing phosphoric acid (or other liquid) electrolyte with an anode catalyst (12) on one side and a cathode catalyst (13) on the other side includes an anode substrate (16a) in contact with the anode catalyst and a cathode substrate (17a) in contact with the cathode catalyst, the anode substrate being thicker than the cathode substrate by a ratio of between 1.75 to 1.0 and 3.0 to 1.0. Non-porous, hydrophobic separator plate assemblies (19) provide fuel flow channels (20) and oxidant flow channels (21) as well as demarcating the fuel cells.
摘要:
The reactant gas manifolds (12–15) of a PEM fuel cell are modified to provide insulated manifolds (14a) having inner and outer walls (30, 31) closed off by a peripheral wall (35) to provide a chamber (36) which may be filled with a vacuum, a low thermal conductivity gas, a VIP (59) or a GFP (63). Single walled manifolds (14d, 14e) may have VIPs or GFPs inside or outside thereof. An insulation panel (40) similarly has inner and outer walls (42, 43) closed with a peripheral wall (45) so as to form a chamber (46) that may contain a vacuum, a low thermal conductivity gas, a VIP or a GFP. The tie rods 9a may be recessed 50 into the pressure plate 11a of the fuel cell stack to allow a flush surface for the insulation panel 40.