United Technologies Corporation

Electric Power Research Institute Incorporated

Glen J Goller

Richard D Breault

Joseph R Salonia

Vincent J Petraglia

Richard J Roethlein

J Harold Smith

George Dews

Gilbert C Sprecher

A process for fabricating a resin bonded carbon fiber article, and in particular electrochemical cell electrode substrates and the like requiring different mean pore sizes in different areas, involves simultaneously heating and compacting different mixtures of carbon fibers and resin in different areas of an article forming mold, wherein the carbon fibers in each of the different mixtures have different, known bulk densities. The different bulk densities of the carbon fibers in the mixtures are chosen to yield the desired mean pore sizes and other properties in the article after heating and compacting the mixtures. Preferably, the different bulk densities are obtained using different carbon fiber lengths in the molding mixtures. The process is well suited to forming ribbed electrode substrates with preselected optimum mean pore sizes, porosities, and densities in the ribs, the webs connecting the ribs, and in the edge seals.

Process for fabricating ribbed electrode substrates and other articles

A ribbed substrate for an electrochemical cell electrode is made from a mixture of carbon fibers and carbonizable resin and has a mean pore size in the ribs which is 60-75% of the mean pore size of the web portions of the substrate which interconnect the ribs. Preferably the mean pore size of the web portion is 25-45 microns; and, if the substrate includes edge seals parallel to the ribs, the edge seals preferably have a mean pore size no greater than about ten microns. Most preferably the substrate has the same ratio of carbon fibers to polymeric carbon in all areas, including the ribs, webs, and edge seals. A substrate according to the present invention will have better overall performance than prior art substrates and minimizes the substrate thickness required for the substrate to perform all its functions well.

Ribbed electrode substrates

A method for making an electrochemical cell electrode involves depositing a layer of dry carbon/hydrophobic polymer powder on the surface of a substrate by dispersing the powder as a cloud in a chamber over the substrate and pulling the powder onto the substrate by drawing a vacuum under the substrate. The electrode is subsequently compacted and sintered. Typically the carbon component of the powder is catalyzed, such as with platinum. Thus, the method is for applying a catalyst layer on an electrode substrate. The method is particularly adapted to the high speed manufacture of electrodes.

Dry method for making an electrochemical cell electrode

A method for making an electrochemical cell electrode involves depositing a layer of dry carbon/hydrophobic polymer floc powder on the surface of a substrate by dispersing the powder as a cloud in a chamber over the substrate and pulling the powder onto the substrate by drawing a vacuum under the substrate. The electrode is subsequently compacted and sintered. Typically the carbon component of the floc is catalyzed, such as with platinum. Thus, the method is for applying a catalyst layer on an electrode substrate. The method is particularly adapted to the high speed manufacture of electrodes.

Dry floc method for making an electrochemical cell electrode

An electrochemical cell including an electrolyte retaining matrix layer located between and in contact with cooperating anode and cathode electrodes is disclosed herein. Each of the electrodes is comprised of a ribbed (or grooved) substrate including a gas porous body as its main component and a catalyst layer located between the substrate and one side of the electrolyte retaining matrix layer. Each substrate body includes a ribbed section for receiving reactant gas and lengthwise side portions on opposite sides of the ribbed section. Each of the side portions includes a channel extending along its entire length from one surface thereof (e.g. its outer surface) to but stopping short of an opposite surface (e.g. its inner surface) so as to provide a web directly between the channel and the opposite surface. Each of the channels is filled with a gas impervious substance and each of the webs is impregnated with a gas impervious substance so as to provide a gas impervious seal along the entire length of each side portion of each substrate and between the opposite faces thereof (e.g. across the entire thickness thereof).

Electrochemical cell including ribbed electrode substrates

A process for making dry carbon/polytetrafluoroethylene floc material, particularly useful in the manufacture of fuel cell electrodes, comprises of the steps of floccing a co-suspension of carbon particles and polytetrafluoroethylene particles, filtering excess liquids from the co-suspension, molding pellet shapes from the remaining wet floc solids without using significant pressure during the molding, drying the wet floc pellet shapes within the mold at temperatures no greater than about 150.degree. F., and removing the dry pellets from the mold.

Automated catalyst processing for cloud electrode fabrication for fuel

Fuel cell electrodes of uniform quality are made on a continuous basis using screen printing. A wet floc is first made by floccing a co-suspension of carbon and hydrophobic polymer. The floc is dried, reduced to a fine powder, and re-suspended in an inking vehicle. The ink is then screen printed onto a porous substrate and the inking vehicle is removed such as by heating. The layer is compacted, sintered, and then catalyzed such as with platinum.

Screen printing method for making an electrochemical cell electrode

A method for making an electrochemical cell electrode involves depositing a layer of mechanically blended dry catalyzed carbon powder and dry hydrophobic polymer powder on the surface of a substrate by dispersing the mixture of powders as a cloud in a chamber over the substrate and pulling the powder onto the substrate by drawing a vacuum under the substrate. The method is particularly adapted to the high speed manufacture of electrodes.

Growing community of inventors

West Springfield, MA, United States of America

Glen J Goller