Proton exchange membrane fuel cell power system

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer;
• and
• a binding agent positioned between the first and second diffusion layers, and the third and fourth diffusion layers.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion laver is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer, and wherein
• the third and fourth diffusion layers comprise a porous hydrophobic lamina, and wherein the porous hydrophobic lamina is coated with a liquid suspension comprising about 95% to about 99% by weight of water;
• about 1% to about 5% by weight of alcohol;
• and about 1% to about 5% by weight of a compatible surfactant.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer, and wherein the first and second diffusion layers comprise a composite of successive coatings, and wherein each of the successive coatings has a specific degree of hydrophobicity, and wherein the first and second diffusion layers have a hydrophobic gradient, and wherein the hydrophobic gradient is established by adjusting the hydrophobicity of the successive coatings forming the composite.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer;
• and wherein the third and fourth diffusion layers comprise a porous hydrophobic lamina which are coated with a liquid suspension comprising about 95% to about 99% by weight of water;
• and about 1% to about 5% by weight of a surfactant.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion laver having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer, and wherein the first and second diffusion layers comprise a composite of successive coatings, and wherein each of the successive coatings has a specific degree of hydrophobicity, and wherein the first and second diffusion layers have a hydrophobic gradient, and wherein the hydrophobic gradient is established by adjusting the hydrophobicity of the successive coatings forming the composite, and wherein the successive coatings closest to the third and fourth diffusion layers are the least hydrophobic of all the successive coatings.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer, and wherein the first and second diffusion layers comprise a composite of successive coatings, and wherein each of the successive coatings has a specific degree of hydrophobicity, and wherein the first and second diffusion layers have a hydrophobic gradient, and wherein the hydrophobic gradient is established by adjusting the hydrophobicity of the successive coatings forming the composite, and wherein the successive coatings closest to the third and fourth diffusion layers are the most hydrophobic of all the successive coatings.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces, and wherein the first surface of said catalytic anode is placed in ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second surfaces, and wherein the first surface of said catalytic cathode is placed in ionic contact with said second surface of said electrolyte membrane;
• a first electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic anode;
• a second electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said second diffusion layer is placed in ohmic electrical contact with the second surface of said catalytic cathode;
• a third electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said third diffusion layer is placed in ohmic electrical contact with said second surface of said first diffusion layer;
• a fourth electrically conductive diffusion layer having first and second surfaces, and wherein the first surface of said fourth diffusion layer is placed in ohmic electrical contact with said second surface of said second diffusion layer, and wherein the diffusion layers disposed on the catalytic cathode side of the membrane electrode diffusion assembly have different diffusion characteristics from the diffusion layers disposed on the catalytic anode side.

A membrane electrode diffusion assembly comprising:

• an electrolyte membrane having opposing first and second substantially planar surfaces;
• a catalytic anode having opposing first and second substantially planar surfaces;
• said first planar surface of said catalytic anode placed into ionic contact with said first planar surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second substantially planar surfaces;
• said first planar surface of said catalytic cathode placed into ionic contact with said second planar surface of said electrolyte membrane;
• a first electrically conductive diffusion layer placed in ohmic electrical contact with the second planar surface of said catalytic anode;
• and
• a second electrically conductive diffusion layer placed in ohmic electrical contact with the second planar surface of said catalytic cathode, and wherein at least one of the first or second diffusion layers has a hydrophobic gradient.

A membrane electrode diffusion assembly as claimed in 11, wherein the individual catalytic anode and catalytic cathode electrodes comprise:

• particulate carbon;
• a catalyst;
• and
• a cross-linked copolymer incorporating sulfonic acid groups.

A membrane electrode diffusion assembly, comprising:

• an electrolyte membrane having opposing first and second surfaces;
• a catalytic anode having opposing first and second surfaces;
• said first surface of said catalytic anode placed into ionic contact with said first surface of said electrolyte membrane;
• a catalytic cathode having opposing first and second planar surfaces placed into ionic contact with said second planar surface of said electrolyte membrane;
• a first electrically conductive diffusion layer placed into ohmic electrical contact with the second planar surface of said catalytic anode;
• and
• a second electrically conductive diffusion layer placed into ohmic electrical contact with the second planar surface of said catalytic cathode, and wherein a binding agent is placed between at least one of the diffusion layers and the underlying catalytic anode or catalytic cathode.

A membrane electrode diffusion assembly as claimed in 20, wherein the individual catalytic anode and catalytic cathode comprise:

• particulate carbon;
• a catalyst;
• and
• a cross-linked copolymer incorporating sulfonic acid groups.