Modified diffusion layer for use in a fuel cell system

A membrane electrode assembly comprising;

• a protonically conductive, electronically non-conductive membrane;
• at least one diffusion layer which includes indented channels formed therein, providing preferential flow paths to cause liquids to travel in predetermined directions in the assembly thereby providing a path through which liquid reactants and byproducts may be preferentially transported to direct said liquid reactants and byproducts in predetermined directions in said assembly;
• and
• a catalyst disposed on said membrane and said catalyst forming an active area of said assembly.

A direct oxidation fuel cell, comprising:

• (A) a membrane electrode assembly, including:
• (i) a protonically conductive, electronically non-conductive membrane electrolyte, having an anode face and an opposing cathode face;
• and
• (ii) a catalyst coating disposed on at least one of said anode face and said cathode face, whereby electricity-generating reactions occur upon introduction of fuel solution from an associated fuel source, including anodic conversion of said fuel solution into carbon dioxide, protons and electrons, and cathodic combination of protons, electrons and oxygen from an associated source of oxygen, producing water;
• (B) an anodic diffusion layer disposed in intimate contact with said anode face of said membrane electrode assembly which allows said associated fuel mixture to pass through to said anode face as fuel is consumed at said anode, and which also allows anodically-generated CO2 to be transported away from the anode face of the membrane;
• (C) a cathodic diffusion layer disposed in intimate contact with said cathode face of said membrane electrode assembly and which allows oxygen to pass through to said cathode face of said membrane electrode assembly, which cathode diffusion layer is comprised of a carbon-containing substrate and a microporous layer having channels formed therein to provide preferential flow paths such that liquid reactants and byproducts in said fuel cell travel in predetermined directions along said channels;
• and
• (D) means for collecting electric current generated in said electricity-generating reactions to provide said electric current to a load.

A direct oxidation fuel cell system comprising:

• (A) a direct oxidation fuel cell including:
• (i) a membrane electrode assembly, including:
• a.) a protonically conductive, electronically non-conductive membrane electrolyte, having an anode face and an opposing cathode face;
• and
• b.) a catalyst coating disposed on at least one of said anode face and said cathode face, whereby electricity-generating reactions occur upon introduction of fuel solution from an associated fuel source, including anodic conversion of said fuel solution into carbon dioxide, protons and electrons, and cathodic combination of protons, electrons and oxygen from an associated source of oxygen, producing water;
• (ii) an anodic diffusion layer disposed in intimate contact with said anode face of said membrane electrode assemblywhich allows said associated fuel mixture to pass through to said anode face as fuel is consumed at said anode, and also allows anodically-generated CO2 to be transported from the anode face of the membrane;
• (iii) a cathodic diffusion layer disposed in intimate contact with said cathode face of said membrane electrode assemblywhich allows oxygen to pass through to said cathode face of said membrane electrode assembly, and which cathodic diffusion layer is comprised of a carbon-containing substrate and a microporous layer having channels formed therein to provide preferential flow paths such that liquid reactants and byproducts in said fuel cell travel in predetermined directions along said channels;
• and
• (iv) means for collecting electric current generated in said electricity-generating reactions to provide said electric current to a load;
• (B) a fuel source;
• (C) fuel container and delivery assembly coupled between said fuel source and said direct oxidation fuel cell;
• (D) means for removing reactants from the fuel cell;
• (E) means for removing byproducts from the membrane electrode assembly;
• (F) electrical coupling means for connecting the fuel cell with an external device to which is it providing power.

A method of fabricating a liquid removing diffusion layer for a protonically conductive membrane used in a direct oxidation fuel cell, the method including the steps of:

• (A) providing a substrate substantially of carbon;
• (B) treating the substrate by coating it with a microporous layer of material that is electrically conductive, hydrophobic and permeable to gases;
• and
• (C) forming, in said microporous layer, channels, producing preferential flow paths to direct liquids in predetermined directions in said fuel cell.