Fuel cell having a hydrophilic substrate layer

Abstract

Fuel Cell Having a Hydrophilic Substrate Layer A fuel cell power plant includes a fuel cell having a membrane electrode assembly (MEA), disposed between an anode support plate and a cathode support plate, the anode and/or cathode support plates include a hydrophilic substrate layer having a predetermined pore size. The pressure of the reactant gas streams is greater than the pressure of the coolant stream, such that a greater percentage of the pores within the hydrophilic substrate layer contain reactant gas rather than water. Any water that forms on the cathode side of the MEA will migrate through the cathode support plate and away from the MEA. Controlling the pressure also ensures that the coolant water will continually migrate from the coolant stream toward the anode side of the MEA, thereby preventing the membrane from becoming dry. Proper pore size and a pressure differential between coolant and reactants improves the electrical efficiency of the fuel cell.

We claim:  
     
         1 . A fuel cell, comprising: 
 an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;    a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream; and    a partially hydrophobic porous carbon fluoropolymer particulate composite diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly, each said diffusion layer comprising about 10% fluoropolymer by weight.    
     
     
         2 . A fuel cell according to  claim 1  wherein: 
 said diffusion layer comprises a fluoropolymer selected from the group consisting of polytetrafluoroethylene, fluorinated ethylene propylene, polytetrafluoroethylene-co-perfluoromethyl vinylether, copolymers of ethylene and tetrafluoroethylene, copolymers of ethylene and chlorotrifluoroethylene, polyvinyldene fluoride, polyvinyl fluoride and amorphous fluropolymers.  
 
     
     
         3 . A fuel cell, comprising: 
 an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;    a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream; and    a diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly, the thickness of each said diffusion layer being more than about 5.0 microns and less than 25.0 microns.    
     
     
         4 . A fuel cell, comprising: 
 an anode support plate and a cathode support plate and a membrane electrode assembly disposed between said anode and cathode support plates, said membrane electrode assembly comprising a polymer electrolyte membrane, at least one of said support plates comprising a hydrophilic substrate layer having pores therein;    a water transport plate adjacent to each said hydrophilic substrate layer, each said water transport plate having a passageway for a water stream and another passageway for a reactant gas stream;    a diffusion layer disposed between at least one said hydrophilic substrate layer and said membrane electrode assembly; and    means for creating pressure differential between said reactant gas streams and said coolant stream such that the pressure of each said reactant gas stream is greater than the pressure of said coolant stream, said pressure differential being more than zero psi and less than two psi.