Abstract: An improved plate-and-frame assembly selectively transfers a fluid component from one fluid stream to another fluid stream. In a preferred embodiment, a plate-and-frame humidity exchanger with unitary plates and seals transfers water vapor and heat between two fluid streams.
Type:
Grant
Filed:
May 27, 1999
Date of Patent:
January 9, 2001
Assignee:
Ballard Power Systems Inc.
Inventors:
Russell H. Barton, Brian Wells, Joel A. Ronne
Abstract: A volume efficient, layered manifold assembly is disclosed for an array of one or more internally manifolded fuel cell stacks. The assembly comprises a stack of substantially planar layers in which each pair of adjacent layers defines a fluid distribution chamber or plenum. Appropriate passages connect each chamber to the internal manifolds of the fuel cell stacks and to various external fluid ports for supply or exhaust of fuel, oxidant, or coolant streams. Passages for at least one fluid penetrate the layers defining the distribution chamber for another fluid. Valving can be incorporated directly in the manifold assembly and used to periodically reverse the direction of fluid flow through internal manifolds of the fuel cell stacks.
Abstract: Fuel cell performance in liquid feed fuel cells with an electrode comprising a carbonaceous substrate and an electrocatalyst can be increased by oxidizing the carbon substrate, particularly by electrochemical methods in acidic aqueous solution, prior to incorporation of the electrocatalyst. The treated substrate may thereafter be advantageously impregnated with a proton conducting ionomer to prevent excessive penetration of the applied catalyst into the substrate. The treatment method is particularly effective for direct methanol fuel cell anodes.
Type:
Grant
Filed:
October 16, 1998
Date of Patent:
November 28, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
Kevin M. Colbow, Jiujun Zhang, David P. Wilkinson
Abstract: Reactant gas supply streams for solid polymer fuel cells may be heated and humidified using heat generated by the fuel cell and water vapor from the fuel cell exhaust. The heat and water vapor in the oxidant exhaust stream are sufficient to heat and humidify a reactant gas supply stream, preferably the oxidant supply stream. The heating and humidifying can be accomplished by flowing a reactant gas supply stream and a fuel cell exhaust gas stream on opposite sides of a water permeable membrane in a combined heat and humidity exchange apparatus. The method and apparatus are particularly suitable for use with air-cooled fuel cell systems and systems which employ near ambient pressure air as the oxidant gas supply.
Type:
Grant
Filed:
June 30, 1998
Date of Patent:
August 22, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
Henry H. Voss, Russell H. Barton, Brian W. Wells, Joel A. Ronne, Harald Anton Nigsch
Abstract: A method and apparatus is provided for operating an electrochemical fuel cell with periodic momentary fuel starvation at the anode. It is believed that such momentary periodic fuel starvation conditions cause the anode potential to increase, resulting in the oxidation and removal of electrocatalyst poisons from the anode electrocatalyst and improved fuel cell performance. In a preferred method, while successive localized portions of the fuel cell anode are momentarily periodically fuel starved, the remainder of the fuel cell anode remains electrochemically active and saturated with fuel such that the fuel cell is continually available to generate power.
Type:
Grant
Filed:
December 23, 1997
Date of Patent:
August 1, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
David P. Wilkinson, Clarence Y. F. Chow, Derek E. Allan, deceased, by Patricia Joanne Allan, administrator, Erik P. Johannes, Joy A. Roberts, Jean St-Pierre, Cindy J. Longley, John K. K. Chan
Abstract: An electrochemical cell stack comprises a plurality of membrane electrode assemblies interposed between pairs of separator plates. The stack comprises adhesively bonded layers. Preferably each membrane electrode assembly is adhesively bonded to the adjacent pair of separator plates. The adhesive bond between the plate and membrane electrode assembly preferably provides a substantially gas and liquid-tight seal around the perimeter of the electrochemically active area of the membrane electrode assembly and around any fluid manifold openings formed therein. Alternatively, or in addition, adjoining pairs of separator plates in an electrochemical cell stack may be adhesively bonded together. Such pairs of adhesively bonded plates may define cooling spaces between neighboring cells. Stacks comprising a plurality of individual cell modules may be formed, each module comprising a membrane electrode assembly bonded to a pair of separator plates.
Abstract: A method is provided for treating electrocatalyst particles and using the treated electrocatalyst for improving performance in an electrochemical fuel cell. The treatment method comprises impregnating pores of the electrocatalyst particles with an impregnant wherein the pores comprise micropores which have an aperture size less than 0.1 micron. The impregnant is preferably ion-conducting and may comprise an organic acid, an inorganic acid, or a polymer. Alternatively, or in addition, the impregnant has an oxygen permeability greater than that of water. The method of impregnating the electrocatalyst particles preferably comprises the steps of contacting the electrocatalyst particles with an impregnant and subjecting the electrocatalyst particles to a vacuum and/or an elevated pressure above atmospheric pressure. The treated electrocatalyst particles are incorporated into an electrochemical fuel cell.
Type:
Grant
Filed:
March 6, 1998
Date of Patent:
June 13, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
David P. Wilkinson, Stephen A. Campbell, Joy A. Roberts
Abstract: An electrochemical fuel cell stack with improved reactant manifolding and sealing includes a pair of separator plates interposed between adjacent membrane electrode assemblies. Passageways fluidly interconnecting the anodes to a fuel manifold and interconnecting the cathodes to an oxidant manifold are formed between adjoining non-active surfaces of the pairs of separator plates. The passageways extend through one or more ports penetrating the thickness of one of the plates thereby fluidly connecting the manifold to the opposite active surface of that plate, and the contacted electrode. The non-active surfaces of adjoining separator plates in a fuel cell stack cooperate to provide passageways for directing both reactants from respective stack fuel and oxidant supply manifolds to the appropriate electrodes. The fuel and oxidant reactant streams passageways are fluidly isolated from each other, although they both traverse adjoining non-active surfaces of the same pair of plates.
Type:
Grant
Filed:
July 16, 1998
Date of Patent:
May 23, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
Joel A. Ronne, Boguslaw M. Wozniczka, Clarence Y. Chow, Henry H. Voss
Abstract: An integrated electrochemical fuel cell power plant, including a fuel processing subsystem is suitable for use in a submarine. Selection and control of operating temperatures and pressures in the various subsystems and components of the fuel cell power plant are important aspects of submarine power plant design. A catalytic burner is used to heat a heat transfer fluid, which in turn is used to heat a vaporizer and reformer in the fuel processing subsystem. A hydrogen separator is used to obtain a substantially pure hydrogen fuel stream from the reformate stream, which is directed to and recirculated through the fuel cell stack in a closed-loop. The fuel processor is operated at high pressure which facilitates the discharge of waste exhaust streams overboard, and the fuel cell is operated at a substantially lower pressure.
Abstract: A membrane electrode assembly for an electrochemical fuel cell includes a pair of electrodes and an ion exchange membrane interposed therebetween. At least one of the electrodes comprises a porous electrode substrate. The substrate comprises a preformed macroporous web having a through-plane resistivity of greater than 1 .OMEGA.*cm. The web contains an electrically conductive filler. A method for preparing the membrane electrode assembly includes the steps of (a) forming a porous electrode substrate for an electrochemical fuel cell by filling a preformed macroporous web, the web having a through-plane resistivity of greater than 1 .OMEGA.*cm, with an electrically conductive filler and (b) consolidating the electrode pair and ion exchange membrane to form a unitary assembly.
Type:
Grant
Filed:
December 21, 1998
Date of Patent:
May 9, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
Stephen A. Campbell, Juergen Stumper, David P. Wilkinson, Michael T. Davis
Abstract: An improved membrane electrode assembly ("MEA") comprises coextensive ion exchange membrane and electrode layers and a resilient fluid impermeable integral seal made by impregnating a sealing material into the porous electrode layers in the sealing regions. The integral seal preferably circumscribes the electrochemically active area of the MEA. In addition, the integral seal preferably extends laterally beyond the edge of the MEA, enveloping the peripheral region including the side edge of the MEA. The uncured sealant material is preferably a flow processable elastomer that is applied to the MEA using a vacuum injection molding process. In preferred embodiments, the seal has a plurality of spaced, parallel raised ribs with cross-ribs extending therebetween at spaced intervals. The parallel raised ribs and cross-ribs provide compartmentalized seals that provide improved protection against fluid leaks.
Type:
Grant
Filed:
July 15, 1998
Date of Patent:
May 2, 2000
Assignee:
Ballard Power Systems Inc.
Inventors:
Russell H. Barton, Peter R. Gibb, Joel A. Ronne, Henry H. Voss
Abstract: An electrochemical fuel cell stack comprises a first end plate, a second end plate, and fuel cell assemblies interposed between the first and second end plates. The stack further includes a compression assembly comprising a compression mechanism and a restraining mechanism. The compression mechanism urges the first end plate towards the second end plate applying an internal compressive force to the fuel cell assemblies, even as the thickness of the fuel cell assemblies changes. The restraining mechanism prevents movement of the first end plate away from the second end plate by preventing deflection of the compression mechanism, which may occur, for example, when internal fluid pressure is increased.
Abstract: An electrochemical fuel cell stack includes a plurality of fuel cell assemblies interposed between a pair of end plate assemblies. The mechanism for securing the stack in its compressed, assembled state includes at least one compression band which circumscribes the end plate assemblies and interposed fuel cell assemblies of the stack. At least one of the end plate assemblies is sufficiently thin so as to deflect under the compressive force if the at least one end plate assembly is supported only at a peripheral edge portion thereof. Preferably, at least one of the end plate assemblies comprises a resilient member which cooperates with each compression band to urge the first end plate assembly toward the second end plate assembly, thereby applying compressive force to the fuel cell assemblies to promote sealing and electrical contact between the layers forming the fuel cell stack.
Type:
Grant
Filed:
June 12, 1998
Date of Patent:
November 30, 1999
Assignee:
Ballard Power Systems Inc.
Inventors:
Boguslaw Wozniczka, Nicholas J. Fletcher, Peter R. Gibb
Abstract: A composite membrane is provided in which a porous substrate is impregnated with a polymeric composition comprising various combinations of .alpha.,.beta.,.beta.-trifluorostyrene, substituted .alpha.,.beta.,.beta.-trifluorostyrene and ethylene-based monomeric units. Where the polymeric composition includes ion-exchange moieties, the resultant composite membranes are useful in electrochemical applications, particularly as membrane electrolytes in electrochemical fuel cells.
Abstract: An electrochemical fuel cell comprises a pair of separator plates and a pair of fluid distribution layers interposed between the separator plates. At least one of the fluid distribution layers comprises a sealing region and an electrically conductive, fluid permeable active region, and a preformed sheet material extending into each of the sealing region and the active region. An ion exchange membrane is interposed between at least a portion of the fluid distribution layers, and a quantity of electrocatalyst is interposed between at least a portion of each of the fluid distribution layers and at least a portion of the membrane, thereby defining the active region. Compression of the preformed sheet material by urging of the pair of plates towards each other renders the at least one fluid distribution layer substantially fluid impermeable in a direction parallel to the major planar surfaces, in the sealing region.
Type:
Grant
Filed:
May 1, 1997
Date of Patent:
November 2, 1999
Assignee:
Ballard Power Systems Inc.
Inventors:
David P. Wilkinson, Juergen Stumper, Stephen A. Campbell, Michael T. Davis, Gordon J. Lamont
Abstract: A method and apparatus are provided for distributing water produced by the electrochemical reaction to an ion-exchange membrane in a electrochemical fuel cell. Water distribution within a fuel cell is improved to reduce membrane dryness near the oxidant stream inlet and to also reduce saturation of the oxidant stream near the oxidant stream outlet, thereby reducing electrode flooding. The method comprises periodically reversing the flow direction of an oxidant stream through a fuel cell flow field. The apparatus comprises an oxidant stream flow switching device for periodically switching the flow direction of an oxidant stream through a fuel cell flow field. In one embodiment the apparatus further comprises a water recycler for capturing water from the oxidant exhaust stream and returning the captured water to the oxidant supply stream when the flow direction is reversed.
Type:
Grant
Filed:
December 1, 1997
Date of Patent:
August 10, 1999
Assignee:
Ballard Power Systems Inc.
Inventors:
Clarence Y. F. Chow, John Ka Ki Chan, Adrian James Corless
Abstract: The invention provides a polymer electrolyte fuel cell with distributor plates which are made of an elastic, plastically deformable material, particularly of graphite foil, and which have integrated gas or liquid ducts. In order to seal off the gas or liquid spaces with respect to one another in a simple and reasonably priced manner, elevated portions are integrated in the distributor plates made of an elastic, plastically deformable material. The distributor plates with an integrated seal can be produced by stamping using a stamping tool having corresponding elevations for forming the gas or liquid ducts and corresponding indentations for forming the sealing arrangement.
Abstract: In an electrochemical fuel cell, a sufficient quantity of catalyst, effective for promoting the reaction of reactant supplied to an electrode, is disposed within the volume of the electrode so that a reactant introduced at a first major surface of the electrode is substantially completely reacted upon contacting the second major surface. Crossover of reactant from one electrode to the other electrode through the electrolyte in an electrochemical fuel cell is thereby reduced.
Type:
Grant
Filed:
September 29, 1997
Date of Patent:
February 23, 1999
Assignee:
Ballard Power Systems Inc.
Inventors:
David P. Wilkinson, Mark C. Johnson, Kevin M. Colbow, Stephen A. Campbell
Abstract: A porous electrode substrate for an electrochemical fuel cell comprises at least one preformed web having low or poor electrical conductivity. The web contains an electrically conductive filler. A method for preparing a porous electrode substrate for an electrochemical fuel cell comprises the step of filling a preformed web, the web having low or poor electrical conductivity, with an electrically conductive filler.
Type:
Grant
Filed:
December 18, 1996
Date of Patent:
January 26, 1999
Assignee:
Ballard Power Systems Inc.
Inventors:
Stephen A. Campbell, Juergen Stumper, David P. Wilkinson, Michael T. Davis
Abstract: In an electrochemical fuel cell, an electrode substrate has an in-plane nonuniform structure. The electrode substrate having an in-plane nonuniform structure enables controlled transport of reactant toward the electrocatalyst layer and controlled transport of reaction product away from the electrocatalyst layer.
Type:
Grant
Filed:
August 25, 1995
Date of Patent:
November 24, 1998
Assignee:
Ballard Power Systems Inc.
Inventors:
Mark C. Johnson, David P. Wilkinson, Charles P. Asman, Myles L. Bos, Robert J. Potter