Laminated fluid flow field assembly for electrochemical fuel cells

Claim 2

A laminated fluid flow field assembly for an electrochemical fuel cell, said assembly comprising: a separator layer formed of electrically conductive, substantially fluid impermeable sheet material, said separator layer having two oppositely facing major surfaces; a stencil layer formed of electrically conductive sheet material, said stencil layer having two oppositely facing major surfaces, said stencil layer having a fluid inlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said fluid inlet; means for consolidating said separator layer and said stencil layer along one of their respective major surfaces, whereby said separator layer and said stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said fluid inlet.

Claim 3

The laminated fluid flow field assembly of claim 1 wherein said stencil layer has a fluid outlet formed therein, and wherein said at least one opening comprises at least one inlet opening extending from said fluid inlet and at least one outlet opening extending from said fluid outlet, said at least one inlet opening being discontinuous with respect to said at least one outlet opening, whereby said separator layer and said stencil layer cooperate to form at least two open-faced channels for conducting pressurized fluid introduced at said fluid inlet to said fluid outlet.

Claim 4

The laminated fluid flow field assembly of claim 2 wherein said at least one inlet opening comprises an inlet header opening extending from said fluid inlet and a plurality of inlet branch openings extending from said inlet header opening, and wherein said at least one outlet opening comprises an outlet header opening extending from said fluid outlet and a plurality of outlet branch openings extending from said outlet header opening.

Claim 5

The laminated fluid flow field assembly of claim 2 wherein said at least one outlet opening comprises a plurality of separate outlet openings, each pair of adjacent outlet channels having an inlet opening disposed therebetween along a substantial portion thereof.

Claim 6

The laminated fluid flow field assembly of claim 4 wherein said at least one outlet opening comprises at least three separate outlet openings and wherein each inlet opening disposed between each pair of adjacent outlet openings is separate with respect to the remainder of said inlet openings.

Claim 7

The laminated fluid flow field assembly of claim 1 wherein said stencil layer has a fluid outlet formed therein, and wherein said at least one opening extends continuously between said fluid inlet and said fluid outlet, whereby said separator layer and said stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said fluid inlet to said fluid outlet.

Claim 8

The laminated fluid flow field assembly of claim 1 wherein said stencil layer is a first stencil layer, said assembly further comprising: a second stencil layer formed of electrically conductive sheet material, said second stencil layer having two oppositely facing major surfaces, said second stencil layer having a fluid inlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said inlet; means for consolidating said separator layer and said second stencil layer along the major surface of said separator layer facing away from said first stencil layer, whereby said separator layer and said second stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said fluid inlet of said second stencil layer.

Claim 9

The laminated fluid flow field assembly of claim 1 wherein said separator layer is formed from a consolidated plurality of individual layers of electrically conductive sheet material, at least one layer of which is substantially fluid impermeable.

Claim 10

The laminated fluid flow field assembly of claim 1 wherein said stencil layer is formed from a consolidated plurality of individual layers of electrically conductive sheet material.

Claim 11

The laminated fluid flow field assembly of claim 1 wherein at least one of said separator layer and said stencil layer is formed from graphite foil.

Claim 12

The laminated fluid flow field assembly of claim 10 wherein both of said separator layer and said stencil layer are formed from graphite foil.

Claim 13

An electrochemical fuel cell for converting a fluid fuel stream and a fluid oxidant stream to a reaction product stream and electrical energy, said fuel cell comprising: first and second laminated fluid flow field assemblies, each of said assemblies comprising: a separator layer formed of electrically conductive, substantially fluid impermeable sheet material, said separator layer having two oppositely facing major surfaces; a stencil layer formed of electrically conductive sheet material, said stencil layer having two oppositely facing major surfaces, said stencil layer having a fluid inlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said inlet; means for consolidating said separator layer and said stencil layer along one of their respective major surfaces; whereby said separator layer and said stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said inlet; a membrane electrode assembly interposed between said first and second laminated fluid flow field assemblies, said membrane electrode assembly comprising: an anode having a catalyst associated therewith to render a region of said anode electrocatalytically active wherein cations are produced from said fluid fuel stream; a cathode having a catalyst associated therewith to render a region of said cathode electrocatalytically active wherein an electrochemical reaction between said cations and said fluid oxidant stream is promoted; a solid polymer ion exchange membrane disposed between said anode assembly and said cathode assembly, said membrane facilitating the migration of cations from said anode assembly to said cathode assembly and isolating said fluid fuel stream from said fluid oxidant stream; an electrical path for conducting electrons formed at said anode assembly to said cathode assembly.

Claim 14

An electrochemical fuel cell for converting a fluid fuel stream and a fluid oxidant stream to a reaction product stream and electrical energy, said fuel cell comprising: first and second laminated fluid flow field assemblies, each of said assemblies comprising: a separator layer formed of electrically conductive, substantially fluid impermeable sheet material, said separator layer having two oppositely facing major surfaces; a stencil layer formed of electrically conductive sheet material, said stencil layer having two oppositely facing major surfaces, said stencil layer having a fluid inlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said inlet; means for consolidating said separator layer and said stencil layer along one of their respective major surfaces; whereby said separator layer and said stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said inlet; a membrane electrode assembly interposed between said first and second laminated fluid flow field assemblies, said membrane electrode assembly comprising: an anode having a catalyst associated therewith to render a region of said anode electrocatalytically active wherein cations are produced from said fluid fuel stream; a cathode having a catalyst associated therewith to render a region of said cathode electrocatalytically active wherein an electrochemical reaction between said cations and said fluid oxidant stream is promoted; a solid polymer ion exchange membrane disposed between said anode assembly and said cathode assembly, said membrane facilitating the migration of cations from said anode assembly to said cathode assembly and isolating said fluid fuel stream from said fluid oxidant stream; an electrical path for conducting electrons formed at said anode assembly to said cathode assembly.

Claim 15

The electrochemical fuel cell of claim 12 wherein each of said stencil layers is a first stencil layer, at least one of said first and second laminated fluid flow field assemblies further comprising: a second stencil layer formed of electrically conductive sheet material, said second stencil layer having two oppositely facing major surfaces, said second stencil layer having a fluid inlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said inlet; means for consolidating said separator layer and said second stencil layer along the major surface of said separator layer facing away from said first stencil layer; whereby said separator layer and said second stencil layer cooperate to form at least one open-faced channel for conducting pressurized fluid introduced at said fluid inlet of said second stencil layer to the electrode of an adjacent membrane electrode assembly.

Claim 16

The electrochemical fuel cell of claim 12, further comprising a cooling assembly adjacent one of said separator layers on the side facing away from said membrane, said cooling assembly comprising: a coolant separator layer formed of electrically conductive, substantially fluid impermeable sheet material, said separator layer having two oppositely facing major surfaces; a coolant stencil layer interposed between said adjacent separator and said coolant separator layer, said coolant stencil layer formed of electrically conductive sheet material having two oppositely facing major surfaces, said coolant stencil layer having a coolant inlet and a coolant outlet formed therein and having at least one opening formed therein extending between the major surfaces thereof, said at least one opening in fluid communication with said coolant inlet and said coolant outlet; means for consolidating said coolant separator layer and said coolant stencil layer along one of their respective major surfaces; whereby said coolant separator layer and said coolant stencil layer cooperate to form at least one open-faced channel for conducting pressurized coolant fluid between said coolant inlet and said coolant outlet.

Claim 17

The electrochemical fuel cell of claim 14 wherein the major surface of said coolant separator layer facing away from said coolant stencil layer cooperates with another stencil layer to form a laminated fluid flow field assembly of an adjacent fuel cell.

Claim 20

The fabrication method of claim 16 wherein said stencil layer is a first stencil layer, said fabrication method further comprising the steps of: providing a second stencil layer formed of electrically conductive sheet material, said second stencil layer having two oppositely facing major surfaces; forming a fluid inlet in said second stencil layer; forming at least one opening extending between the major surfaces of said second stencil layer, said at least one opening in fluid communication with said inlet; consolidating said separator layer and said second stencil layer along the surface of said separator layer facing away from said first stencil layer.