Patent ID: 7267902

Claim:
A unitized membrane electrode assembly comprising: (a) a first porous gas diffusion backing layer having sealing edges substantially uniformly impregnated with a fluid-impermeable polymer; (b) a polymer electrolyte membrane having outer edges within the outer edges of the first and second gas diffusion backing layers; (c) a first electrocatalyst layer positioned between said first diffusion backing layer and said polymer electrolyte membrane, said electrocatalyst layer being essentially coextensive with said polymer electrolyte membrane surface; (d) a second porous gas diffusion-backing layer having sealing edges substantially uniformly impregnated with a fluid-impermeable polymer; (e) a second electrocatalyst layer positioned between said second diffusion backing layer and said polymer electrolyte membrane, said electrocatalyst layer being essentially coextensive with said polymer electrolyte membrane surface; (f) at least one frame-shaped insulation layer positioned within the unitized membrane electrode assembly such that it prevents contact between the first and second gas diffusion backing layers, the outer edges of the polymer electrolyte membrane overlapping with the inner edges of said insulation layer; and (g) a fluid-impermeable polymeric seal that envelops the outer edges of the polymer electrolyte membrane.