Patent Publication Number: US-2009220833-A1

Title: Fuel Cell Device

Description:
This application claims priority of U.S. provisional application Ser. No. 60/719,285, filed Sep. 21, 2005, and Ser. No. 60/753,340, filed Dec. 22, 2005. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to a fuel cell device for generating electricity from hydrogen and oxygen. 
     BACKGROUND 
     Hydrogen fuel cells generate electricity from hydrogen and oxygen. Such fuel cells may include a stack of fuel cell modules, each module including a negative electrode (or anode) and a positive electrode (or cathode) sandwiching an electrolyte such as a proton-permeable membrane. Hydrogen is fed to the anode, and oxygen to the cathode. Hydrogen atoms separate into protons and electrons at the anode, the protons passing through the membrane to the cathode and the electrons moving along a current path to the cathode to complete an electrical circuit and create an electrical current. The protons that have migrated through the electrolyte to the cathode reunite with oxygen and the electrons in an exothermic reaction producing water. Each fuel cell module connects in series with the other modules in the stack to increase electrical potential. 
     It&#39;s also known for each such fuel cell module in a stack to include a membrane electrode assembly (MEA) and a bipolar separator plate (BSP). Each MEA includes a proton-permeable membrane that may be sandwiched between two current collector layers and may also include gas diffusion layers sandwiching the membrane and current collector layers. Each BSP comprises a plate of conductive material such as stainless steel or graphite and includes gas channels etched or machined in a side of the BSP that is to contact the MEA. In the stack of modules, each BSP serves as a cathode for an MEA on one side and as an anode for an MEA on the other side. 
     SUMMARY OF THE DISCLOSURE 
     A fuel cell device ( 10 ) is provided for generating electricity from hydrogen and oxygen. The device comprises a membrane electrode assembly ( 12 ), a bipolar separator plate ( 14 ) supported adjacent and generally parallel to the membrane electrode assembly, and a contact array ( 18 ,  64 ) providing electrical contact between the membrane electrode assembly and the bipolar separator plate. The contact array comprises a plurality of compliant electrical contacts ( 20 ) that are partibly retained between the membrane electrode assembly and the bipolar separator plate. This allows the contact array to be easily installed during fuel cell stack ( 11 ) assembly and easily removed and/or replaced during fuel cell stack maintenance. 
     According to another aspect of the disclosure, a fuel cell device ( 10 ) is provided in which the contact array ( 18 ,  64 ) comprises a plurality of electrically-conductive resilient tubes ( 52 ,  56 ) disposed and providing electrical contact between the membrane electrode assembly and the bipolar separator plate. 
     A method is also provided for making a fuel cell. The method includes the steps of providing a membrane electrode assembly ( 12 ) and a bipolar separator plate ( 14 ), and partibly retaining a resilient contact array ( 18 ) between the membrane electrode assembly ( 12 ) and the bipolar separator plate ( 14 ). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages will become apparent to those skilled in the art in connection with the following detailed description, drawings, photographs, and appendices, in which: 
         FIG. 1  is an orthogonal view of a fuel cell device constructed according to the invention; 
         FIG. 2  is a partial front end view of the fuel cell device of  FIG. 1 ; 
         FIG. 3  is a perspective view of a gas manifold of the fuel cell device of  FIG. 1 ; 
         FIG. 4  is a cross-sectional partial top view of the fuel cell device of  FIG. 1  taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a cross-sectional partial end view of the fuel cell device of  FIG. 1  taken along line  5 - 5  of  FIG. 4  and showing compliant tubular electrical contacts of the device arranged on a bipolar separator plate of a module of the device and between gas manifolds of the module; 
         FIG. 6  is a cross-sectional partial top view of an alternative embodiment of the fuel cell device of  FIG. 1  including layers of compliant tubular electrical contacts on both the anode and the cathode side of each membrane electrode assembly of each module of the fuel cell device; 
         FIG. 7  is a partial cross-sectional view of the alternative fuel cell device of  FIG. 6  taken along line  7 - 7  of  FIG. 6  and showing compliant tubular electrical contacts arranged on an anode side of a membrane electrode assembly of a module of the device within a gas delivery chamber of the module; 
         FIG. 8  is a cross-sectional partial side view of the fuel cell device of  FIG. 6  taken along line  8 - 8  of  FIG. 7  and looking lengthwise through the tubular electrical contacts disposed within gas delivery chambers of the device; 
         FIG. 9  is a cross-sectional partial top view of another alternative embodiment of the fuel cell device of  FIG. 1  including resilient conductive mats arranged on an anode side of the membrane electrode assembly of each module of the device within the gas delivery chamber of each module; 
         FIG. 10  is a cross-sectional partial end view of the fuel cell device of  FIG. 9  taken along line  10 - 10  of  FIG. 9 ; 
         FIG. 11  is a cross-sectional partial side view of the fuel cell device of  FIG. 9  taken along line  11 - 11  of  FIG. 10 ; 
         FIG. 12  is a cross-sectional partial end view of an alternative embodiment of the fuel cell device of  FIG. 9  including resilient conductive mats arranged in gas delivery chambers defined in part by chambers formed into the BSPs of each module of the device; 
         FIG. 13  is a cross-sectional partial side view of the fuel cell device of  FIG. 12 ; 
         FIG. 14  is a schematic cross-sectional side view of a fuel cell device constructed according to the invention showing air being blown through the device with an outflow restrictor of the device in an open position; 
         FIG. 15  is a schematic cross-sectional partial side view of the fuel cell device of  FIG. 14  with the outflow restrictor in a partially-closed position restricting the outflow of air from the device. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION EMBODIMENT(S) 
     A first embodiment of a fuel cell device for generating electricity from reactant gasses such as hydrogen and oxygen is generally shown at  10  in  FIGS. 1-5 . A second embodiment is shown at  210  in  FIGS. 6-8 . A third embodiment is shown at  310  in  FIGS. 9-11 . A fourth embodiment is shown at  410  in  FIGS. 12 and 13 . Unless indicated otherwise, where a portion of the following description uses a reference numeral to refer to elements of the first embodiment shown in  FIGS. 1-5 , that portion of the description applies equally to elements of the second embodiment identified by the same reference numeral plus  200  in  FIGS. 6-8 , the elements of the third embodiment identified by the same reference numeral plus  300  in  FIGS. 9-11 , and elements of the fourth embodiment identified by the same reference numeral plus  400  in  FIGS. 12 and 13 . 
     As best shown in  FIG. 4  the device  10  may include a stack  11  of membrane electrode assemblies (MEAs)  12  and bipolar separator plates (BSPs)  14  supported adjacent and generally parallel to the MEAs  12 . The BSPs  14  comprise a sheet or plate of conductive material such as stainless steel or graphite and include flow channels  16  that may be etched or machined into the BSPs in a reactant flow pattern to direct the flow of reactant gas across adjacent MEAs  12  as is well known in the art. The MEAs  12  may be of the polymer electrolyte variety used in Polymer Electrolyte Membrane (PEMFC) and Direct Methanol (DMFC) fuel cells. However, in other embodiments, the MEAs  12  could be of the solid oxide variety used in solid oxide (SOFC) fuel cells or the molten carbonate variety used in molten carbonate (MCFC) fuel cells. Where the MEAs  12  are of the polymer electrolyte variety, they each may include a polymer electrolyte membrane sandwiched by layers of material that may include electrode, catalyst, and gas diffusion layers as is well known in the art. 
     As is also best shown in  FIG. 4 , the device  10  may include cathode contact arrays  18  sandwiched between the MEAs  12  and the BSPs  14  on a cathode side of each MEA  12 . Each such array  18  comprises a plurality of compliant electrical cathode contacts  20  providing electrical contact between the BSPs  14  and the cathode sides of the MEAs  12 . The cathode contacts  20  of each cathode contact array  18  are in electrical contact with but need not be permanently attached to either the MEA  12  or the BSP  14  that the arrays  18  are sandwiched between. In other words, the cathode contacts  20  of each cathode contact array  18  may be separable or partible from and may be separably or partibly interposed between, i.e., may be in separable or partible physical contact with and may be separably or partibly engaged and retained by friction between the BSP  14  and MEA  12  that the cathode contact array  18  is sandwiched between or is in contact with. 
     Because the cathode contacts  20  of the cathode contact array  18  are not attached, the cathode contact array  18  can be easily installed during assembly of a fuel cell stack  11  and can also be easily removed and replaced when defective, or temporarily removed as required for fuel cell stack maintenance. Although, in the embodiment of  FIG. 4  the cathode contact array  18  is shown sandwiched between MEAs  12  and BSPs  14  only on a cathode or oxygen side of each MEA  12  in a fuel cell stack  11 , in other embodiments, and as described below, a contact array may be disposed on the anode or hydrogen side of each MEA  12  in a fuel cell stack  11 , or contact arrays may be disposed on both the anode and cathode sides of each MEA  12  in a stack  11 . 
     As shown in  FIG. 4 , each fuel cell stack  11  may include a plurality of separable or partible fuel cell modules  22  that are not only physically connected but are electrically connected in series, as well. Each such module  22  may include an MEA  12  bonded and sealed to a BSP  14  defining a gas delivery chamber  23  between the MEA  12  and the flow channels  16  of each BSP  14 . Each module  22  may also include one or more gas manifolds  24 ,  26  that may be bonded and sealed to the BSP  14 . A gas delivery chamber seal  28  that may comprise, for example, a sealant adhesive or an adhesive backed gasket, may partially define the gas delivery chamber  23  by sealing and bonding the MEA  12  and manifolds  14 ,  26  to the BSP  14  in each module  22 . The gas manifolds  24 ,  26 , a single one of which is shown in perspective in  FIG. 3 , may be identical to one another and one or both may serve as reactant gas intake manifolds in dead-ended operation, or, in circulatory operation one may serve as an intake manifold  24  and the other as an exhaust manifold  26 . The gas manifolds  24 ,  26  each include a manifold through-hole  30  and a branching passageway  32  that carries reactant and/or purge gases to and/or from an active region or gas delivery chamber  23  defined between the MEA  12  and the BSP flow channels  16  of each module  22  on an anode side of the MEA  12 . 
     Each BSP  14  may include two BSP through-holes  36  that allow gasses to flow between the manifold branching passageways  32  and the gas delivery chamber  23 . Surrounding each such BSP through-hole  36  between the BSP  14  and the associated gas manifold  24 ,  26  may be an adhesive seal  35  that both adheres the gas manifolds  24 ,  26  of each module  22  to the BSP  14  of that module  22 , and prevents reactant gas from escaping from between the gas manifold  24 ,  26  and the BSP  14  in regions surrounding the BSP through-holes  36 . 
     As is also shown in  FIG. 4 , when the fuel cell modules  22  are stacked together, the manifold through-holes  30  are coaxially aligned and interconnected to form a trans-manifold gas passage  38  that extends through the manifolds  24 ,  26  of all the modules  22  in the stack  11  and that leads to a fitting or connector  40  to which a gas pressure regulator and a gas source, or a purge line may be connected. The gas manifolds  24 ,  26  may be sealed to one another by O-rings  42  that are placed in respective annular O-ring grooves  44  and pressed against a sealing surface on a gas manifold  24 ,  26  of an adjacent fuel cell module  22 . 
     Oxygen may be provided through the convective passage of ambient air through the arrays  18  of compliant cathode contacts  20  disposed on the cathode sides of the MEAs  12  of a fuel cell stack  11 , or by the forced passage of air propelled by an air propeller such as a ducted fan  46  as shown in  FIG. 14  or other suitable air delivery means. Air pressure near the membranes may be increased by any suitable means to include restricting the outflow of air from the stack  11  while blowing air into the stack  11  as shown in  FIG. 15 . The outflow restriction may, for example, be controlled by controlling an outflow restrictor  48  that may include louvers  50  disposed across an outflow side of the fuel cell stack  11 . The device  10  may include an electronic controller  49  connected to the outflow restrictor  48  and programmed to maximize power output by controlling the position of the outflow restrictor  48  in response to inputs from humidity, temperature, and/or electrical current or power sensors  51   a ,  51   b ,  51   c . Humidity and temperature sensors  51   a ,  51   b , may be supported adjacent one or more of the MEAs of the fuel cell stack and electrical current or power sensors  51   c  may be positioned to sense individual module current flow or power output; and/or stack current flow or power output. Outflow restricting louvers  48  are shown in a fully open position in  FIG. 14  and in a partially-closed, outflow restricting position in  FIG. 15 . Oxygen may alternatively be provided to the cathode sides of the MEAs  12  in the form of pure oxygen or pressurized air from a pressurized air source. 
     As shown in  FIGS. 1 ,  4 , and  5 , each cathode contact array  18  may comprise a plurality of resilient cathode-side tubes  52 . Each cathode-side tube  52  may be of any suitable cross-sectional shape and may, as best shown in  FIG. 5 , comprise a helix, or helically-wound electrically-conductive length of metal ribbon of generally circular or oval cross-sectional shape. Windings  54  of each helix act as a series of flexible electrical contact springs. The resilient cathode-side tubes  52  may be disposed parallel to and adjacent one-another between an MEA  12  and a BSP  14 . As best shown in  FIG. 5 , each cathode contact array  18  may have the same approximate length and width as the MEA  12  whose cathode side the array  18  is associated with. In the depicted embodiments the cathode-side tubes  52  are partibly retained. However, in other embodiments the cathode-side tubes  52  may alternatively be connected to one, the other, or both the MEA  12  and the BSP  14  in each module  22 . 
     Suitable resilient tubes of helically-wound metal ribbon are available from Spira Manufacturing Corporation of North Hollywood, Calif. The electrically-conductive metal ribbon comprises low cost spring temper stainless steel, which provides excellent spring memory and compression set resistance. The metal ribbon may either be electro-plated with tin (90% tin and 10% lead per AMS-P-81728) or gold. 
     The resilient cathode-side tubes  52  may be compressed between the cathode or oxygen side of an MEA  12  of one module  22  and the BSP  14  of another module  22  as shown in  FIG. 4 . Alternatively or additionally, resilient anode-side tubes  56  may be compressed between the anode or hydrogen side of an MEA  12  and the BSP  14  of the same module  22  as shown in  FIGS. 6-8  and as if further discussed below with regard to the second embodiment  210 . In either case, the compression of the tubes  52 ,  56  may optimally amount to 25% of the diameter of the tube. The force required to compress each tube  52 ,  56  is a function of the cube of the thickness of the stainless steel ribbon. 
     As shown in  FIGS. 4 and 7 , the windings  54  of the helically-wound ribbon may be spaced from each other by a helical gap extending the length of each tube. This may provide a certain amount of cyclonic or vortex motion in reactant gas passing through the tubes  52 ,  56 . Vortex motion of reactant gas passing through cathode-side tubes  52  can increase oxygen intrusion into a gas diffusion layer of the MEAs  12  on the cathode side and, if used on the anode side, can increase hydrogen proton passage through the MEA  12  from the anode side. The increase of oxygen intrusion and/or hydrogen ion passage through the MEA  12  may be caused by a centrifugal dispersion of reactant gases through the gaps in the tubes  52 ,  56  towards the MEA  12 . Another effect of centrifugal dispersion may be an increase in reactant gas turbulence at the MEA  12  which may occur when centrifugally-dispersed gas mixes with gas passing along and between the tubes  52 ,  56 . 
     As shown in  FIG. 4 , two conductive current-collector layers  58  comprising, for example, sheets of metal foil, are disposed at each end of the stack  11  of fuel cell modules  22 . As shown in  FIG. 1 , two electrodes  59  are connected to the current-collector layers  58  to allow an electrical load to be applied to the stack  11 . Two non-conductive end plates  60  may cap the ends of the stack  11  and lie flush against the current-collector layers  58 . 
     Fasteners  62  passing through the end plates  60  and manifolds  24 ,  26  may be tightened to compress the cathode-side tubes  52  to the point where the manifolds  24 ,  26  have been drawn together and lie flush with one another. The manifolds  24 ,  26  may be shaped and sized so that when they are drawn into a flush relationship with one another the cathode-side tubes  52  will be compressed by a desired amount, e.g., 25 percent as discussed above and as shown in  FIG. 4 . 
     The stack  11  may be oriented so that the cathode-side tubes  52  of the array  18  are oriented vertically as shown in  FIG. 1 . This greatly improves convective heat transfer from the stack  11 , and allows the convection to improve the circulation of oxygen-bearing air to the cathode side of each fuel cell module  22  when, for example, a forced-air system, such as the one shown in  FIGS. 14 and 15 , is either not in use or is inoperative. 
     As shown in  FIGS. 6-8  the second fuel cell device embodiment  210  also includes a stack  211  of fuel cell modules  222 , each such module  222  including an MEA  212  and a BSP  214 . This device  210  may be identical to the device  10  of the first embodiment except that it may include a second array of electrical contacts or anode contact array  64  for each fuel cell module  222 . As best shown in  FIGS. 6 and 8 , the anode contact arrays  64  are disposed and provide electrical contact between the BSP  214  and the corresponding MEA  212  of each fuel cell module  222  of a stack  211 . The anode contact arrays  64  provide electrical contact between the MEAs  212  and the BSPs  214  on an anode side of each MEA  212  in each fuel cell module  222  of the stack  211 . In other words, in each module  222 , the anode contact array  64  is disposed on the anode side of the MEA  212 . 
     As with the cathode contact array  218  the anode contact array  64  of the second embodiment  210  may comprise a plurality of resilient anode-side tubes  56 , each such tube  56  comprising a helix, i.e., a helically-wound electrically-conductive length of metal ribbon. The windings  54  of the helix of each anode-side tube  56  define flexible electrical contact springs along the length of each anode-side tube  56 . As best shown in  FIG. 7  the resilient anode-side tubes  56  of the anode contact array  64  of each module  222  are disposed generally parallel to and adjacent one-another and are compressed between the MEA  212  and the BSP  214  of each module  222 . 
     As best shown in  FIG. 7 , the anode contact array  64  of each module  222  may have the same approximate length and width as the MEA  212  of that module  222  except that the anode contact array  64  is bordered by a gas delivery chamber seal  228  disposed between the outer edges of the MEA  212  and the BSP  214 . According to the second embodiment  210 , the chamber seal  228  may comprise a gasket and/or adhesive strips or compressed beads of adhesive that both prevent hydrogen gas from escaping the chamber  223  and space the MEA  212  from the BSP  214  sufficiently to provide room for the anode contact array  64  to be disposed within the gas delivery chamber  223 . In other words, the anode contact array  64  of electrical contacts is encased in the gas delivery chamber  223  defined by the MEA  212  on one side, the BSP  214  on the other side, and a gas delivery chamber seal  228  bordering the anode contact array  64 . 
     When hydrogen gas is introduced into the space between the anode side of an MEA  212  and an adjacent BSP  214  of a module  222 , i.e., into its gas delivery chamber  223 , the hydrogen may be directed to flow into the chamber  223  through one or both gas manifolds  224 ,  226  of the module  222  and then through and between each resilient anode-side tube  56  of the anode contact array  64 . This allows the gas to contact the MEA  212 , hydrogen ions to be transported through the MEA  212  toward the cathode side of the MEA  212 , and electrons to travel through the anode contact array  64  to the BSP  214  of the module  222 . 
     The resilient anode-side tubes  56  of the anode contact array  64 , as with those of the first cathode contact array  18 , may be helically-wound metal ribbons such as those available from Spira Manufacturing Corporation of North Hollywood, Calif. and described in detail above and in Appendix  1 . They may be disposed parallel to and adjacent one-another between the MEA  212  and the BSP  214  of each module  222  as shown in  FIGS. 6-8 . The resilient anode-side tubes  56  are compressed between the MEA  212  and the BSP  214  of each module  22  as shown in  FIGS. 6 and 8 . 
     As with the first and second embodiments, the third embodiment  310  of  FIGS. 9-11  includes a stack  311  of fuel cell modules  322 , each including an MEA  312  and a BSP  314 . As with the second embodiment  210  each module  322  of the third embodiment  310  includes an anode contact array  364 . However, unlike the second embodiment  210  the anode contact array  364  in each module  322  according to the third embodiment  310  may comprise a mat  66  of, for example, metal strands such as stainless steel wool. In other words, one or more of the anode contact arrays  364  may comprise resilient conductive mats  66  that, as shown in  FIGS. 9-11 , are removably disposed between the MEAs  312  and BSPs  314  of each module  322 . The mats  66  may comprise metal material such as interwoven or intermeshed or tangled metal strands such as stainless steel wool or open-celled metal foam or sponge material. Such mats  66  would both provide electrical current flow between the BSPs  314  and the anode sides of the MEAs  312 , and would at the same time allow for the passage of reactant gas. 
     Alternatively, or additionally, and according to the fourth embodiment shown in  FIGS. 12 and 13 , the gas delivery chambers  423  of each module  422  may include a recess  68  formed in the BSP  414  of each module  422 . As is best shown in  FIG. 13 , such recesses  68  provide additional headroom for contact arrays  464  disposed within the gas delivery chambers of the stacked modules  422  and may preclude the need to include gaskets or sealing strips between the BSPs  414  and the anode sides of the MEAs  414  of each module  422 . 
     Such a fuel cell device  10  can be made by first providing a plurality of MEAs  12  and BSPs  14 , and connecting, i.e., sealing and adhering the MEAs  12  to respective BSPs  14  and the BSPs to respective gas manifolds  24 ,  26  to form fuel cell modules  22 . If an anode contact array  264 ,  364  is to be included in each module  222 ,  322  then in constructing each module a chamber seal  28 ,  328  is adhered and sealed to the BSP  214 ,  314  the array  264 ,  364  is disposed on the BSP within a perimeter defined by the chamber seal  28 ,  328 ; and the MEA is sealed and adhered to the chamber seal. Alternatively, rather than, or in addition to using chamber seals, recesses  68  may be formed in the BSPs  414  of each module  422  to form gas delivery chambers  423 , and the anode contact arrays  464  positioned within the recesses  68  before adhering the MEAs  412  to the BSPs  414 . 
     Once the fuel cell modules  22  have been formed, the stack  11  may then be assembled by removably sandwiching resilient contact arrays  18  between the fuel cell modules  22  such that each resilient contact array  18  is disposed and provides electrical contact between the MEA  12  of one fuel cell module  22  and the BSP  14  of an adjacent fuel cell module  22  as shown in  FIGS. 2 and 8 . 
     The cathode contact arrays  18  may be sandwiched between modules  22  one at a time by first supporting a first cathode contact array  18  either on the MEA  12  or on the separator plate of a first one of the fuel cell modules  22 . A second fuel cell module  22  may then be supported on the first cathode contact array  18  such that, if the MEA  12  of the first fuel cell module  22  is supporting and contacting the first cathode contact array  18 , then the BSP  14  of the second fuel cell module  22  is placed in contact with the first cathode contact array  18 . Conversely, if the BSP  14  of the first fuel cell module  22  is supporting and contacting the first cathode contact array  18 , then the MEA  12  of the second fuel cell module  22  is placed in contact with the first cathode contact array  18 . This procedure is then repeated for the remainder of the contact arrays  18  and modules  22 . The cathode contact arrays  18  may then compressed between the modules  22  as shown in  FIGS. 3 and 8  by inserting and tightening fasteners  62  between the end plates  60  and through the gas manifolds  24 ,  26 . 
     In sandwiching the cathode contact arrays  18  between the fuel cell modules  22 , where each cathode contact array  18  comprises a plurality of resilient cathode-side tubes  52  comprising helically-wound electrically-conductive lengths of metal ribbon, the cathode-side tubes  52  may be spaced carefully apart or simply disposed in a loose side-by-side arrangement as shown in  FIG. 4  as the stack is being assembled and before the arrays  18  are compressed. The cathode-side tubes  52  may be spaced far enough apart or placed loosely enough so as to leave sufficient room for the cathode-side tubes  52  to expand radially when compressed between the modules  22  as best shown in  FIG. 9 . 
     The use of compliant electrical cathode contact arrays  18  and the adhesive sealing of MEAs  12  obviates the need for high compression forces to be applied to the stack  11 , and, consequently, the need for thick BSPs  14  and precise parallelism between the plates in a stack  11 . Where graphite BSPs  14  are used, the vastly reduced stack compressive forces preclude BSP breakage and high scrap rates associated with the manufacture of fuel cell stacks incorporating graphite BSPs  14 . Only enough compressive force is required to compress the electrical cathode contact arrays  18  to the point where the fuel cell modules  22  are seated together, with the manifolds  24 ,  26  providing proper spacing between BSPs  14 . Compliant electrical anode contact arrays  64  allow for the use of gas delivery chambers in place of reactant gas channels  16  in BSPs  14  on the anode sides of MEAs  12 . Because the contact arrays  18 ,  64  may be partibly retained between the BSPs  14  and MEAs  12  they may simply be laid in place during stack assembly rather than attached to the BSPs in advance. Accordingly, the use of compliant partibly retained electrical cathode contact arrays  18  can greatly speed and ease the manufacture of fuel cell stacks. 
     This description is intended to illustrate certain embodiments of the invention rather than to limit the invention. Therefore, it uses descriptive rather than limiting words. Obviously, it&#39;s possible to modify this invention from what the description teaches. Within the scope of the claims, one may practice the invention other than as described.