United Technologies Corporation

International Fuel Cells, LLC

Electrochem, Inc.

Calvin L Bushnell

Vinod M Jalan

Alexander Boris Shelekhin

Douglas J Wheeler

Harold R Kunz

Craig R Schroll

Lawrence J Bregoli

John A Bett

Michael S Pien

Christopher L Davis

An air-cooled, hydrogen-air solid polymer electrolyte (SPE) fuel cell with a membrane electrode assembly operatively associated with a fluid flow plate having at least one plate cooling channel extending through the plate and at least one air distribution hole extending from a surface of the cathode flow field into the plate cooling channel.

Air-cooled, hydrogen-air fuel cell

Solid polymer membrane fuel cell product water which forms on the oxidant side of the membrane is removed from the active area of the cells in a fuel cell power plant by being absorbed into and wicked away from the active area by a porous carbon body which contacts the membrane. The carbon body may be an oxidant reactant flow field plate. The pores in the carbon body are partially filled with metal oxide granules which impart increased wettability and water absorption capacity to the carbon body.

Porous carbon body with increased wettability by water

Gaps occurring between a cathode substrate and a gas housing in a fuel cell interfere with electron transfer in the cell causing high cell internal resistance. To reduce the high resistance gaps are closed by coating the substrate with metal powder that expands during oxidation closing the gaps.

Coated cathode substrate

A fuel cell (10) system in which a nitrogen (N.sub.2) gas is used on the anode section (11) and a nitrogen/oxygen (N.sub.2 /O.sub.2) gaseous mix is used on the cathode section (12) to maintain the cathode at an acceptable voltage potential during adverse conditions occurring particularly during off-power conditions, for example, during power plant shutdown, start-up and hot holds. During power plant shutdown, the cathode section is purged with a gaseous mixture of, for example, one-half percent (0.5%) oxygen (O.sub.2) and ninety-nine and a half percent (99.5%) nitrogen (N.sub.2) supplied from an ejector (21) bleeding in air (24/28) into a high pressure stream (27) of nitrogen (N.sub.2) as the primary or majority gas. Thereafter the fuel gas in the fuel processor (31) and the anode section (11) is purged with nitrogen gas to prevent nickel (Ni) carbonyl from forming from the shift catalyst. A switched dummy electrical load (30) is used to bring the cathode potential down rapidly during the start of the purges. The 0.5%/99.5% O.sub.2 /N.sub.2 mixture maintains the cathode potential between 0.3 and 0.7 volts, and this is sufficient to maintain the cathode potential at 0.3 volts for the case of H.sub.2 diffusing to the cathode through a 2 mil thick electrolyte filled matrix and below 0.8 volts for no diffusion at open circuit conditions. The same high pressure gas source (20) is used via a 'T' juncture ('T') to purge the anode section and its associated fuel processor (31).

Reactant gas composition for fuel cell potential control

Thru-cracks in the electrolyte retaining matrix of a molten carbonate fuel cell caused by thermal cycling of the cell between operating and room temperature are prevented by an improved matrix comprising a major proportion of submicron support particles and a minor proportion, perhaps only a few percent, of much larger crack attenuator particles. In one embodiment wherein the electrolyte is to be a binary lithium-potassium carbonates composition, the matrix comprises 90 volume percent submicron lithium aluminate support particles and 10 volume percent alumina crack attenuator particles with an average size of 100 microns.

Electrolyte matrix for molten carbonate fuel cells

The rate of platinum recrystallization of a platinum supported on carbon catalyst is reduced by depositing porous carbon on and around the supported platinum crystallites. The reduced rate of platinum recrystallization results in higher platinum surface areas over a period of time and therefore improves the performance of the catalyst. The porous carbon can be deposited by any suitable technique, a preferred method being to heat the supported platinum in the presence of carbon monoxide to decompose the carbon monoxide thereby depositing carbon on and around the platinum crystallites.

Catalyst and method for making

The rate of platinum recrystallization of a platinum supported on carbon catalyst is reduced and the activity of the catalyst is increased by depositing porous carbon on and around the supported platinum crystallites and then heating the catalyst in an inert atmosphere or vacuum at a high temperature.

Platinum catalyst and method for making

Method for the production of highly dispersed electrochemically active platinum particles having an average diameter below about 50 A for use in electrodes for fuel cells. Platinum particles are formed by mixing chloroplatinic acid and sodium dithionite in water to provide a platinum containing colloidal dispersion which may be absorbed on a support material. Hydrogen peroxide can be mixed with the chloroplatinic acid and sodium dithionite to improve the stability of the platinum containing colloidal dispersion.

Method for producing highly dispersed catalytic platinum

An electrolyte reservoir layer disposed behind and adjacent one of the catalyst layers of a fuel cell is porous and hydrophilic to the electrolyte. In one embodiment the reservoir layer includes impregnations of hydrophobic material on the catalyst facing surface thereof and holes leading from the other surface to the impregnations for providing reactant gas passages through the reservoir layer to the catalyst layer. The impregnations of hydrophobic material are designed to provide good distribution of the reactant gas into the catalyst layer without consuming a large volume of the reservoir. In a preferred embodiment the reservoir is also the electrode substrate whereby the catalyst layer is bonded to the surface thereof.

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Glastonbury, CT, United States of America

Calvin L Bushnell