Extruded fuel cell stack shunt current prevention arrangement

An integral separator plate for use in a fuel cell stack that includes a plurality of juxtaposed fuel cells, comprising

• a plate-shaped porous anode for one, and a plate-shaped cathode electrode for another, of adjacent ones of the fuel cells;
• a separator plate interposed between said electrodes, delimiting respective interfaces therewith, and having an outer peripheral surface;
• means for unifying said separator plate with said electrodes into the integral separator plate, including respective quantities of electrolyte-nonwettable material each initially present in one of said interfaces in the form of a sheet substantially coextensive with the respective one of said interfaces and most of it being ultimately contained in respective pores of that respective one of said electrodes that adjoins said one interface to prevent fluids present in said one of said electrodes during the use of the integral separator plate from reaching said separator plate;
• and
• means for preventing the flow of electric shunt current in said fuel cell stack between said successive electrodes on said outer peripheral surface of said separator plate of said integral separator plate, including a substantially circumferentially complete barrier constituted by an extruded integral part of at least one of said quantities of said electrolyte-nonwettable material situated at but externally of said respective interface to prevent liquid electrolyte present in at least one of the electrodes during the use of the integral separator plates form migrating between the respective one of said electrodes that adjoins said respective interface and said peripheral surface of said separator plate.

A method of fabricating an integral separator plate for use in a fuel cell stack that includes a plurality of juxtaposed fuel cells, comprising the steps of

• forming an assembly including a plate-shaped porous anode for one, and a plate-shaped cathode electrode for another, of adjacent ones of the fuel cells, a separator plate interposed between the electrodes, delimiting respective interfaces therewith, and having an outer peripheral surface, and sheets of electrolyte-nonwettable material each contained in and substantially coextensive with one of the interfaces;
• and
• simultaneously unifying the separator plate with the electrodes into an integral separator plate and forming a substantially circumferentially complete barrier to flow of electric shunt current in the fuel cell stack between the successive electrodes on the outer peripheral surface of the separator plate of the integral separator plate, including causing most of the electrolyte-nonwettable material of the respective sheet to flow into respective pores of the respective one of the electrodes that adjoins the respective interface to prevent fluids present in said respective electrode during the use of the integral separator plate from reaching said separator plate, and extruding the remainder of such electrolyte-nonwettable material out of the respective interface to form the barrier that prevents liquid electrolyte present in said integral separator plate during the use thereof from migrating between that of said electrodes that adjoins said respective interface and said peripheral surface of said separator plate.