Abstract:
A fuel cell arrangement including a plurality of fuel cells, each fuel cell including an electrolyte membrane disposed between an anode and a cathode, first and second flow field plates adjacent the anode and cathode, respectively; a fuel cell health management (FCHM) device; a plurality of plate members interposed between each of the fuel cells and being made of an electrically conductive metallic material and disposed between the first and second flow field plates of adjacent fuel cells to connect the fuel cells in series, and having an electrically conductive tab. The tab of each of the plate members being electrically connected to the FCHM to conduct current provided by the FCHM to provide a substantially uniform voltage over each electrically of the plate members to rejuvenate each fuel cell, to monitor each fuel cell, and to control each fuel cell, and having a heat sink for dissipating heat.

Description:
RELATED APPLICATIONS 
     The present invention claims priority from U.S. Provisional Patent Application Ser. No. 60/512,782 filed 21 Oct. 2003 and herein incorporates such document by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the electrical connection between fuel cell health management and control systems and fuel cell stacks. More particularly, the present invention relates to an electrical interconnect for use with fuel cell stacks for example polymer electrolyte membrane (PEM) fuel cell stacks. 
     BACKGROUND OF THE INVENTION 
     A fuel cell is an energy conversion device that electrochemically reacts a fuel with an oxidant to generate direct current (DC) power. A fuel cell typically consists of an anode, an electrolyte material and a cathode. In a Polymer Electrolyte Membrane (PEM) fuel cell, the anode and the cathode are bonded onto the polymer electrolyte material to form an individual cell. The individual cell generates a relatively small voltage, typically 0.6-0.7 Volts, but may produce high currents. To achieve higher voltages that are practically useful, electrical interconnects are used to connect a relatively large number of individual cells in series. The electrical interconnect also usually provides passageways which allow the flow of fuel to the anode of each cell, oxidant to the cathode and water for cooling and humidification purposes. These electrical interconnects are commonly referred to as “plates”. 
     The term “plates”, in the present field, incorporates a number of different types of plates, such as end plates, buss plates, fuel/oxidant plates, fuel/cooling (air or liquid) plates and oxidant/cooling (air or liquid) plates. The buss plates are used to collect current from the active area of a fuel cell, and have an extended conductive tab that allows an electrical connection for supplying a load. Typically, two buss plates, located at each end of the active section of the fuel cell stack, are used in a fuel cell stack. The assembly of fuel cells thus formed is referred to as a fuel cell stack. 
     A fuel cell power generation system typically comprises a fuel cell stack that consists of a humidification section and an electrochemically active section although some systems are designed such that humidification of the reactants occurs outside of the fuel cell stack. The humidification section imparts water vapour to the hydrogen containing fuel stream and the oxygen containing oxidant stream that are fed into the fuel cell stack. The electrochemically active section comprises fuel cells for promoting the electrocatalytic conversion of the humidified fuel and oxidant streams to electric current and product water. The electrochemically active section also includes a coolant water stream for absorbing heat generated in the active section. The fuel cell system includes a heat exchanger for removing heat from the coolant water stream exiting the active section, a water separator for removing water from the oxidant stream exiting the fuel cell stack, and a coolant reservoir for receiving the removed water stream from the water separator and from the heat exchanger. The coolant water stream is drawn from the coolant reservoir. An example of the design of such an Integrated Fuel Cell Power Generation System is disclosed in U.S. Pat. No. 5,200,278. In other designs, air is used as the coolant instead of water. 
     The current art of connecting a plurality of individual fuel cells in series to achieve higher voltages leads to the disadvantage that all of the connected fuel cells can be rendered inoperable if one of the fuel cells in the fuel cell stack fails. The probability of failure of a single fuel cell in a stack is not known, but for a given probability of failure, the weakest link theory allows estimation of the probability of failure for a stack that is connected in series. Assume, for example, that a 1 kW stack that consists of 50 fuel cells in series and that each cell has the same probability of failure. If the failure probability for each cell is 0.01over a specified period, then the probability of survival is 0.99. The probability of having a good stack is then 0.99 50  or about 0.60. The probability of failure over the specified period therefore is about 40%, a very high value. Reliability of fuel cell stacks is a major concern for many applications. 
     While the fuel used in low temperature fuel cells may be pure hydrogen, commonly an impure hydrogen stream is used as the fuel source. For example, impure hydrogen produced by reforming hydrocarbon or oxygenated hydrocarbons such as natural gas, propane, or methanol may be used. These impure hydrogen streams commonly contain significant amounts of electrocatalyst poisons such as carbon monoxide, which seriously degrade the power output of the fuel cell stack. Similarly, electrocatalyst poisons can be introduced through the oxidant stream, especially when air is used as the oxidant. Poisoning of fuel cell stacks is another major concern for many applications. 
     In the prior art, the following patents U.S. Pat. Nos. 6,339,313 and 6,541,941, of the same assignee, disclose a means for alleviating both the reliability and poisoning problems outlined above. It is well known that electrocatalyst poisons can be removed from the anode by periodically raising the anode potential and that electrocatalyst poisons can be removed from the cathode by periodically lowering the cathode potential. For example, carbon monoxide can be removed from a platinum electrocatalyst by raising the anode potential to approximately 700 mV vs. a Reference Hydrogen Electrode (RHE). At this potential the carbon monoxide (CO) is oxidized to carbon dioxide (CO 2 ), which is released into the fuel stream. The same patents also disclose that the same devices and methods can be used to supplement a weak cell or by-pass a defective cell in a stack to thereby increase the overall stack reliability. In order to effect poison removal or cell supplementation or by-pass, very large currents which may be equal to or even exceed the maximum stack current must be introduced into the edge of the cell plates and this current must then flow in the plane of the plate to be equally distributed over the surface of the individual cell that is being treated. 
     Presently, the fuel cell plates utilized in PEM fuel cells are commonly made of machined graphite, moulded composite graphite/plastic materials or an inexpensive, flexible sheet material (such as Grafoil™) into which reactant flow fields are pressed. These materials have the advantage that they are chemically stable in the harsh operating environment encountered in a PEM fuel cell and they have a sufficiently high electrical conductivity such that the voltage drop caused by the flow of the stack current through the thin plate (i.e., normal to the plate surface) is sufficiently small. 
     In  FIG. 1  of the prior art, a fuel cell stack assembly  10  is shown. The fuel cell stack assembly  10  includes an electrochemically active section  26  and a humidification section  28 . The stack assembly  10  is a modular plate and frame design, and includes a compression end plate  16  and a fluid end plate  18 . An optional pneumatic piston  17 , positioned within compression end plate  16 , applies uniform pressure to the assembly to promote sealing. Buss plates  22  and  24  located on opposite ends of active section  26  provide the negative and positive contacts, respectively, to draw current generated by the fuel cell stack assembly  10  to a load (not shown). Tie rods  20  extend between end plates  16  and  18  to retain and secure stack assembly  10  in its assembled state with fastening nuts  21 . 
     The active section  26  includes, in addition to buss plates  22  and  24 , a plurality of fuel cell assemblies  12 , each assembly consisting of two fuel cells. The humidification section  28  includes a plurality of humidification assemblies  14 , each assembly consisting of a fuel or oxidant reactant flow field plate, a water flow field plate and a water vapor transport membrane interposed between the reactant flow field plate and the water flow field plate. The humidification section  28  imparts water vapor to the fuel and oxidant streams that are later fed to the active section  26 , thereby preventing the membranes within the active section from drying out. 
       FIG. 2 , of the prior art, is a sectional view of the fuel cell assemblies  12 , which constitute the electrochemically active section of fuel cell stack assembly  10  of  FIG. 1 . In particular, assembly  12  includes graphite flow field plates  42 ,  44  and  54 . Fuel flow field channels  54   b  and  44   b  are engraved or milled into plates  44  and  54  respectively as shown. Oxidant flow field channels  42   a  and  44   a  are engraved or milled into plates  42  and  44 , respectively, as shown. Water flow field channels  42   b  are engraved or milled into plate  42  on the side opposite channels  42   a , as shown. The membrane electrode assemblies  48  are interposed between fuel flow field channels  44   b  and oxidant flow field channels  42   a  and between fuel flow field channels  54   b  and oxidant flow field channels  44   a.    
     Membrane electrode assemblies  48  are essentially identical. Each membrane electrode assembly  48  comprises two layers of porous electrically conductive sheet material, preferably carbon fiber paper, and a solid polymer electrolyte or ion exchange membrane interposed between the two layers of porous electrically conductive sheet material. The sheet material layers are each coated with catalyst, preferably finely divided platinum, on the surfaces adjacent and in contact with the ion exchange membrane to render the sheet material electrochemically active. The two electrodes and ion exchange membrane are heat and pressure consolidated to form membrane electrode assemblies  48 . 
     The existing fuel cell plate designs have electrical and/or physical deficiencies that make connection of the Fuel Cell Health Manager (FCHM) systems disclosed in U.S. Pat. Nos. 6,339,313 and 6,541,941, difficult or impossible. The electrical conductivity of pure graphite is relatively low being of the order of 800×10 −6 /ohm-cm and that of moulded graphite/plastic plates or Grafoil™ several times lower than pure graphite. With typical electrode currents in PEM fuel cell stacks being of the order of 1 A/cm 2 , it can easily be shown that unacceptably large voltage drops (several hundreds of mV) will occur when currents are introduced into the edge of the plates in high power stacks. Such large voltage drops will result in uneven distribution of current through the plates and ineffective removal of fuel cell poisons. Existing fuel cell plates also fail to provide the extensions that are needed for electrical connection of the FCHM to the stack and for heat removal from high power FCHM electronic components such as Metal Oxide Field Effect Transistors (MOSFETs). 
     In view of the above-noted shortcomings, it is therefore desirable to provide an improved electrical interconnect for use in a fuel cell stack which is highly conductive and chemically durable, and suitable for use with a management and control tool such as the FCHM. Furthermore, there is a need for an improved apparatus and method for electrically connecting the FCHM and control systems to fuel cell stacks. In particular, there is a need for an electrical interconnect that has high electrical conductivity so that there is an acceptable level of voltage drop across the plate during poison removal, also termed rejuvenation, and/or cell supplementation and by-pass, that is also chemically stable in the fuel cell operating environment and that can be used as a heat sink or have a heat sink attached for the high power electronic components associated with the FCHM system. In addition, there is a need for an apparatus and method that maintains the benefit of reduced overall size to maintain a high overall power density of the fuel cell system. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to obviate or mitigate at least one disadvantage of previous electrical interconnects. 
     The present invention provides an electrical interconnect for use in a fuel cell stack. The present invention further provides a fuel cell assembly, for use in the electrochemically active section of a fuel cell stack, comprising one or more membrane electrode assemblies (MEA), each disposed between two flow field plates that distribute fuel and oxidant to the anode and the cathode, an additional flow field plate for passing coolant in order to cool the assembly and, possibly, a buss plate. At least one of these plates is an electrical interconnect of the present invention. According to the present invention, the electrical interconnect is constructed to include one or more electrically conductive tabs, where one or more of the tabs are in turn coupled to a Fuel Cell Health Manager (FCHM). The FCHM is able to monitor, control, rejuvenate, supplement, and bypass the fuel cell assembly through the connection made via the tabs. 
     The tabs may also be utilized as mounts and heat sinks for high power electronic components associated with the FCHM, the heat generated by these FCHM components being dissipated by the fuel cell stack cooling system. At least one of these plates is an electrical interconnect of the present invention. According to the present invention, the electrical interconnect is constructed in the form of one or more electrically conductive tabs. The terms “interconnect” and “tab” are interchangeable. The tabs may be formed separately from or integrally with plates of the fuel cell stack. If the tabs are integrated into a plate of the fuel cell stack, then the entire plate with associated tab would be considered the interconnect. The tabs are capable of being coupled to a Fuel Cell Health Manager (FCHM). The FCHM is able to monitor, control, and rejuvenate the fuel cell assembly though the connection made via the tabs. 
     The electrical interconnects are made from a highly electrically conductive material such that the voltage drop across each plate member provided by an FCHM is small thus allowing the current density across the MEA to be essentially uniform. The material of the electrical interconnects is advantageously selected based on its electrical and thermal conductivities and its chemical stability in the operating environment of the fuel cell. The tabs enable a variable output voltage of the fuel cell stack. This could occur by varying the connection across the one or more tabs. For example, the voltage across one end of the fuel cell stack and any given tab located within the stack could be 24V. By varying tabs within the depth of the fuel cell stack, the output voltage could be varied accordingly. 
     The tabs may also be used for heat sinks for high power electronic components associated with the FCHM. The heat generated by these FCHM components begin dissipated by the fuel cell stack cooling system. Moreover, the tab itself may be dimensioned in a manner that would allow for dissipation of excess heat. In other words, the tab itself would also function as a heat sink. 
     The interconnects are made from a highly electrically conductive material such that the voltage drop across each plate member provided by an FCHM is small, thus allowing the current density across the MEA to be essentially uniform. The material of each interconnect is advantageously selected based on its electrical and thermal conductivities and its chemical stability in the operating environment of the fuel cell. A significant benefit of the present invention is that the inventive interconnect creates a more uniform voltage over the plate area due to enhanced conductivity. This, in turn, improves fuel cell stack performance and life. 
     In a first aspect, the present invention provides an electrical interconnect for use with at least one fuel cell assembly and an FCHM or similar device, the FCHM for monitor, control, rejuvenate, supplement, and bypass actions on the at least one fuel cell assembly, each of the at least one fuel cell assembly having a membrane electrode assembly (MEA) with an electrolyte membrane disposed between an anode and a cathode, and further having corresponding flow field plates alongside the anode and the cathode, the electrical interconnect comprising: a plate member being made of highly electrically conductive material such that the voltage drop across each plate member, provided by the FCHM, provides for a uniform current density across the MEA, the plate member being of suitable thermal conductivity and chemical stability for use with the at least one fuel cell assembly, and the plate member being disposed along one of the corresponding flow field plates; and at least one tab having suitable electrical conductivity to enable sufficient current to flow from the FCHM, and the at least one tab dimensioned for operatively connecting the plate member to the FCHM. 
     In a second aspect, a electrical interconnect for use with at least one fuel cell assembly and an FCHM or similar device, the FCHM for monitor, control, rejuvenate, supplement, and bypass actions on the at least one fuel cell assembly, each of the at least one fuel cell assembly having a membrane electrode assembly (MEA) with an electrolyte membrane disposed between an anode and a cathode, and further having corresponding flow field plates alongside the anode and the cathode, the electrical interconnect comprising: a plate member being made of highly electrically conductive material such that the voltage drop across each plate member, provided by the FCHM, provides for a uniform current density across the MEA, the plate member being of suitable thermal conductivity and chemical stability for use with the at least one fuel cell assembly, and the plate member forming one of the corresponding flow field plates; and at least one tab having suitable electrical conductivity to enable sufficient current to flow from the FCHM, and the at least one tab dimensioned for operatively connecting the plate member to the FCHM. 
     In a third aspect, the present invention provides a fuel cell assembly for use in a fuel cell stack with an FCHM or similar device, the fuel cell assembly comprising: a fuel cell assembly, each of the at least of two fuel cells having an electrolyte membrane disposed between an anode and a cathode respectively; a first flow field plate being disposed along a first side of the fuel cell; a second flow field plate being made of high electrically conductive material and for forming an electrical interconnect, the second flow field plate being disposed along a second side of the fuel cell and providing channels for fluid flow within the fuel cell assembly, and the second flow field forming at least one flow field in a surface portion of the second flow field plate to allow for the distribution of the fluid flow to the fuel cell; and a tab being made of electrically conductive material, for electrically connecting the second flow field plate to the FCHM. 
     In a fourth aspect, the present invention provides a fuel cell assembly for use in a fuel cell stack with an FCHM or similar device, the fuel cell assembly comprising: at least one membrane electrode assembly (MIA), each of the at least one MEA having an electrolyte membrane disposed between an anode and a cathode respectively; a first flow field plate being disposed along a first side of the fuel cell; a second flow field being disposed along a second side of the fuel cell; a plate member being made of highly electrically conductive material such that the voltage drop across each plate member, provided by the FCHM, provides for a uniform current density across the MEA, the plate member being of suitable thermal conductivity and chemical stability for use with the at least one MEA, and the plate member being disposed along the second flow field plate; and a tab being made of electrically conductive material, for electrically connecting the plate to the FCHM. 
     In a fifth aspect, the present invention provides a plate for use in a fuel cell stack. The plate includes a tab for conducting current uniformly across the plate. The tab may be separate from or integral with the plate. The tab is also dimensioned such that heat transfer is enabled to increase heat dissipation from the plate. 
     Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures. 
         FIG. 1  is a side elevation view of a fuel cell stack assembly of the prior art showing both the electrochemically active and humidification sections 
         FIG. 2  is a sectional view of the fuel cell stack assembly in the active section of the prior art  FIG. 1 . 
         FIG. 3  is a sectional view of a fuel cell assembly having an electrical interconnect according to a first embodiment of the present invention. 
         FIG. 4  is a sectional view of two fuel cell assemblies disposed between electrical interconnects for operative use with an FCHM according to a second embodiment of the present invention. 
         FIG. 5  is a sectional view of an electrical interconnect according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Generally, the present invention provides an improved interconnect for fuel cell stacks. The invention will be described for the purposes of illustration only in connection with certain embodiments. However, it is to be understood that other objects and advantages of the present invention will be made apparent by the following description of the drawings according to the present invention. While a preferred embodiment is disclosed, this is not intended to be limiting. Rather, the general principles set forth herein are considered to be merely illustrative of the scope of the present invention and it is to be further understood that numerous changes may be made without straying from the scope of the present invention. 
     Referring now to  FIG. 3 , a fuel cell assembly  100  in accordance with the present invention is shown. The fuel cell assembly  100  comprises a typical PEM fuel cell  110 , a first flow field plate  120 , and a second flow field plate  130  forming an electrical interconnect of the present invention, and a tab  140  which is an integral extension of plate  130 . The first flow field plate  120  is disposed along an anode side  110 A of the fuel cell  110 . To provide fuel flow to the anode (not clearly shown) of the fuel cell  110 , fuel flow field channels  150  have been milled into the first flow field plate  120 . The second flow field plate  130  is disposed along a cathode side  110 B of the fuel cell  110 . To provide oxidant flow to the cathode (not shown) of the fuel cell  110 , the second flow field plate  130  provides oxidant flow field channels  155 . The second flow field plate  130  is also constructed with coolant flow field channels  160 . 
     According to the present invention, the second flow field plate  130  is made of a highly electrically conductive material. The material of the plate member may also be selected based on its thermal conductivity and chemically stability in the operating environment of the fuel cell. 
     It should be further mentioned that the tab  140  may be utilized for electrically connecting an FCHM (not shown) to the fuel cell assembly  100  for monitor, control, rejuvenate, supplement, and bypass purposes, as described in prior art patents U.S. Pat. Nos. 6,339,313 and 6,541,941, incorporated herein by reference. While an FCHM is mentioned specifically herein, it should be readily understood that any fuel cell device that monitors, controls, rejuvenates, or otherwise electrically manages one or more fuel cells via electronic circuitry may also benefit from the present inventive interconnect without straying from the intended scope of the present invention. The tab  140  also provides a means for coupling a heat sink to the fuel cell assembly  100  for dissipating heat from the FCHM during the monitor, control, rejuvenate, supplement, and bypass processes. 
       FIG. 4  illustrates a sectional view of a group of fuel cell assemblies  200  according to a second embodiment of the present invention. The group  200  includes two fuel cells  205 ,  210 , disposed between flow field plates  220 ,  230 ,  240 ,  250 , where particular flow field plates also form electrical interconnects  220 ,  230 , in accordance with the present invention and where a further electrical interconnect  260  of the present invention is also included. The flow field plates  220 ,  230 ,  240 ,  250  each provide one or more layers of flow field channels  225 ,  230 ,  235 ,  238 ,  245 ,  255 , respectively. The first flow field plate  220  provides a set of flow field channels  225 . This set of flow field channels  225  may either stream fuel or oxidant to the first fuel cell  205  depending on whether the first flow field plate  220  is disposed along the anode or cathode side of the first fuel cell  205 . The second flow field plate  230  is constructed to provide two flow field channels  235 ,  238 , where a first set of flow field channels  235  stream fuel or oxidant depending on the arrangement of the fuel cell  205 . The second set of flow field channels  238  is utilized for coolant flow. The third flow field plate  240  is disposed along a first side the second fuel cell  210 . The third flow field plate  240  provides a set of channels  245  similar to that of the first flow field plate  220 . The fourth flow field plate  250  is disposed along an opposing side of the second fuel cell  210 . The fourth flow field plate  250  also provides a set of channels  255  for fuel or oxidant flow depending on the arrangement of the second fuel cell  210 . Finally, there is a further electrical interconnect  260  of the present invention disposed along the flow field plate  250 . 
     The electrical interconnects  220 ,  230 ,  260 , are made of material that is highly electrically conductive, such as a metal or a graphite/metal composite structure. More particularly, the electrical interconnect  230  is a composite structure containing two flow field plates  230   a ,  230   b , where a highly conductive metal plate  230   c  is disposed between the two flow field plates  230   a ,  230   b . The flow field plates  230   a ,  230   b  may be made of a graphite material, whereas the metal plate  230   c  may be made of a highly conductive material, such as steel. The materials of the flow field plates and electrical interconnects  220 ,  230 ,  240 ,  250 ,  260  may be further selected based on their thermal conductivity and chemically stability in the operating environment of the two fuel cells  205 ,  210 , respectively. 
     As shown in  FIG. 4 , the electrical interconnects  220 ,  230 ,  260  are either further coupled to a tab  270 A, or have integrated tabs  270 B,  270 C, respectively. The tabs  270 A,  270 B,  270 C are connected to an FCHM  280  for monitor, control, rejuvenate, supplement, and bypass processes on the group of fuel cell assemblies  200 . 
     The tabs  270 A,  270 B,  270 C vary in width along the connection side of the electrical interconnects  220 ,  230 ,  260 , respectively, to enable a suitable electrical connection of the FCHM to the group of fuel cell assemblies  200 . Also, depending on the dimension of the tabs  270 A,  270 B,  270 C, the tabs  270 A,  270 B,  270 C may form an integrated heat sink or have an external heat sink (as shown in  FIG. 5 ) mounted thereon to extract heat from high power electronic components (not shown) of the FCHM  280 . 
       FIG. 5  illustrates a sectional view of an electrical interconnect  300  according to a third embodiment of the present invention. The electrical interconnect  300  is similar the electrical interconnect  230  of  FIG. 4  where the electrical interconnect  300  could be arranged in a group of fuel cell assemblies as is electrical interconnect  230  in  FIG. 4 . In  FIG. 5 , this sectional view shows an oxidant flow field  320  on the oxidant distribution side of the plate  310 . The oxidant flow field  320  is formed in the surface of the plate to allow for distribution of oxidant to the cathode and for removal of product water produced by the operation of the particular fuel cell. The serpentine flow pattern of the oxidant flow field  320  is known in the prior art and will not be further elaborated upon in this document. 
     The electrical interconnect  300  is made from a highly electrically conductive material such that the voltage drop across each plate member, provided by the current from an FCHM, is small. In addition, the material of the plate  310  is advantageously selected based on its thermal conductivity and its chemical stability in the operating environment of the fuel cell. The electrical interconnect  300  also provides a tab  350  that allows for electrical connection to an FCHM (as shown in  FIG. 4 ). While the tab  350  is shown a separate element, the tab may be an integrated extension of the plate  310 . The tab  350  may also be utilized as a heat sink where the heat is extracted from the FCHM components by relying on cooling provided by the coolant flow field plate in the fuel cell assembly. The tab  350  may also be constructed for mounting thereon a heat sink  355 , suitable for any high power FCHM components. 
     As shown in  FIG. 5 , the plate  310  is also provided with ports for the distribution of oxidant to the cathodes of all of the fuel cells in the stack. The oxidant channel ports  360   a ,  360   b  are shown as being connected to the oxidant flow field  320  for oxidant flowing, respectively, in and out of the fuel cell, and in turn through the rest of the fuel cell stack assembly. The plate  310  is also constructed to have fuel fluid flow channels, as well as coolant flow channels.  FIG. 5  shows a sectional view of the fuel fluid flow channels  370   a ,  370   b  and coolant flow channels  380   a ,  380   b.    
     According to the present invention, the plate forming the electrical interconnect of the present invention may be constructed from a metallic material having high conductivity, such as steel or stainless steel, with a corrosion resistant but electrically conductive and chemically durable coating. The electrical interconnect of the present invention may also be constructed from a thin metallic plate or metallic mesh of a highly conductive material such as aluminium which can be used to conduct the FCHM currents to which has been bonded a conductive carbon based plastic material to improve corrosion resistance. A corrosion resistant metal, such as titanium or niobium, which has been coated with platinum or gold to reduce the build-up of resistive oxides at the plate member surface, may also be suitable. The plate can be further inserted into heat removal or humidification sections of a fuel cell stack. 
     It should be understood that a fuel cell stack with a small number of cells may have interconnects that allow each cell to be treated by the FCHM, whereas in a large stack interconnects may be placed to treat groups of cells. A manner in which this may be accomplished is to have several fuel cells in each assembly and one interconnect, perhaps located in the cooling section, within each assembly. Alternatively, there may be an interconnect for every several assemblies. Accordingly, the electrical interconnect of the present invention can be coupled to an individual fuel cell assembly or a group of fuel cell assemblies. A fuel cell stack with a small number of fuel cells, i.e., less than 20, will likely have an electrical interconnect provided for every fuel cell in the stack. In a small fuel cell stack, electrical interconnects are installed at the anode and cathode side of each fuel cell in a stack. Thus, adjacent cells may share an electrical interconnect where the shared electrical interconnect is disposed along the anode side of a first fuel cell and the cathode side of the adjacent fuel cell. To reduce cost, a fuel cell stack with many fuel cells would likely have electrical interconnects to allow regeneration of groups of two fuel cells or more. Typically, there are 2 to 10 fuel cells per fuel cell assembly in a large fuel cell stack. Also, there may be a coolant flow field plate adjacent every fuel cell assembly in a fuel cell stack to provide a cooling section. However, the number of cooling sections may vary, where for example, several fuel cell assemblies share one cooling section. 
     It is also understood that flow field plates in a fuel cell assembly can be converted into electrical interconnects, or have a suitable buss plate disposed along a given flow field plate in a fuel cell assembly to provide an electrical interconnect in the fuel cell assembly. It should be mentioned that electrical interconnects of the present invention can be provided throughout a fuel cell stack, where either flow field plates already provided in the fuel cell stack are converted into electrical interconnects, or buss plates are inserted throughout the fuel cell stack. Again, groups of fuel cell assemblies, in a fuel cell stack, can share a single electrical interconnect. The present invention is not limited to the number of fuel cell assemblies, in a fuel cell stack, which could share an electrical interconnect. 
     The electrical interconnect of the present invention can be provided in humidification and heat removal sections of a fuel cell stack, such as the prior art fuel cell stack  10  of  FIG. 1 , to cool the FCHM. As mentioned previously, the electrical interconnects installed in proximity of the fuel cell stack coolant flow field plates will assist in cooling of the high powered electronic components mounted on them. A typical PEM fuel cell stack runs at a temperature of 80 C  and the typical maximum case temperature of a MOSFET utilized for fuel cell stack rejuvenation is 100 C . By implementing the electrical interconnect of the present invention, the MOSFET would be cooled by the fuel cell stack. The coolest place for the electrical interconnect would be located beside a coolant flow field plate or within the coolant flow field plate as a single hybrid plate. 
     The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.