Ribbed electrode substrates

A fuel cell electrode substrate, said substrate comprising, by weight, 65%-90% carbon fibers and 10%-35% polymeric carbon, the ratio of carbon fibers to polymeric carbon being essentially constant throughout said substrate, said substrate including a flat sheet portion and a plurality of parallel ribs, said ribs extending outwardly from and being integral with one side of said sheet portion forming parallel channels extending across said substrate, said substrate also including edge seal portions contiguous with each edge of said flat sheet portion parallel to said ribs, said flat sheet portion having a mean pore size of 25-45 microns, said ribs having a mean pore size 60%-75% of said flat sheet portion mean pore size, and said seal portions having a mean pore size no greater than about 10 microns, wherein said flat sheet portion has a porosity of 67% to 81% and said ribs have a porosity of 60% to 81%, the average length of carbon fibers throughout said flat sheet portion being greater than the average length of carbon fibers throughout said ribs, and the average length of carbon fibers throughout said ribs being greater than the average length of carbon fibers throughout said seal portions.

An electrochemical cell comprising an anode electrode, a cathode electrode, and a matrix layer sandwiched therebetween for holding electrolyte liquid, each of said electrodes including a substrate comprising, by weight, 65%-90% carbon fibers and 10%-35% polymeric carbon, said substrate including a flat sheet portion and parallel ribs extending outwardly from and being integral with a side of said sheet portion facing away from said matrix layer forming parallel channels extending across said substrate, said flat sheet portion having a mean pore size of 25-45 microns and having a catalyst layer disposed on the side thereof facing the matrix layer and in contact therewith, wherein said ribs have a mean pore size 60-75% of said flat sheet portion means pore size.

An electrochemical cell electrode comprising a substrate and a catalyst layer, said substrate comprising, by weight, 65%-95% carbon fibers and 10%-35% polymeric carbon, said substrate including a flat sheet portion, said catalyst layer being disposed on one side thereof, said substrate including parallel ribs extending outwardly from and being integral with the other side of said sheet portion forming parallel channels extending across said substrate, said flat sheet portion having a mean pore size of 25-45 microns and said ribs having a mean pore size 60%-75% of said flat sheet portion mean pore size.