Fuel cell systems

#This invention relates to fuel cell systems.

#A fuel cell can convert chemical energy to electrical energy by promoting a chemical reaction between two gases.

#One type of fuel cell includes a cathode flow field plate, an anode flow field plate, a membrane electrode assembly disposed between the cathode flow field plate and the anode flow field plate, and two gas diffusion layers disposed between the cathode flow field plate and the anode flow field plate. A fuel cell can also include one or more coolant flow field plates disposed adjacent the exterior of the anode flow field plate and/or the exterior of the cathode flow field plate.

#FIG. 1 is a partial schematic diagram of a prior art fuel cell system;

#FIG. 2 is a partial schematic diagram of a prior art fuel cell system;

#FIG. 3 is a side elevational view, in part cross-section, of an embodiment of a fuel cell assembly having end plates;

#FIG. 3 shows a fuel cell assembly 100 having a fuel cell stack 110 compressed between a service heatable end plate 120 and a blind heatable end plate 140. Heatable end plates 120 and 140 can be heated to inhibit condensation of water from humidified reactants passing through heatable end plate 120 and/or to inhibit heat loss from the ends of fuel cell stack 110.

#Fuel cell stack 110 includes a plurality of fuel cells 20, and a plurality of cooling plates 40 interspersed between the plurality of fuel cells 20 and through which a coolant is recirculated to maintain fuel cell stack 110 at a generally constant operating temperature. Insulation layers 114 and 117, and current collector/conductor plates 115 and 116, are disposed between respective end plates 120 and 140 and the opposite ends of fuel cell stack 110. A plurality of structural members such as elongated bolts 102 and releasably attachable nuts 104 inhibit movement of end plate 120 away from end plate 140.

#FIG. 4 shows an embodiment of a fuel cell 20. Fuel cell 20 includes catalysts 24 and 25 (e.g., platinum) that facilitate fuel cell chemical reactions and are applied to the anode and cathode sides, respectively, of a solid polymer electrolyte 22, such as a solid polymer membrane or a proton exchange membrane (PEM) (e.g., a material available from E.I. Du Pont de Nemours Co. under the trademark NAFION®). Anode and cathode gas diffusion layers 26 and 27, which are formed from a resilient and conductive material such as carbon fabric or carbon fiber paper, are disposed on catalysts 24 and 25, respectively.