IMPROVED GAS DIFFUSION STRUCTURES FOR FUEL CELLS

Designs and structures are disclosed that improve the numerous local functional requirements in the interface region between the electrodes and flow field plates in fuel cells, and particularly in solid polymer electrolyte fuel cell stacks. In the present invention, gas diffusion means are used instead of one or both of the conventional gas diffusion layers. The gas diffusion means comprises a first layer applied to the surfaces of the landings on an adjacent flow field plate and a second layer located between an electrode and the first layer in which the first layer has greater porosity, greater in-plane gas permeability, greater through-plane heat conductivity, and greater through-plane electrical conductivity than the second layer.