E.i. Dupont De Nemours and Company

Shoibal Banerjee

Walther G Grot

William Howard Tuminello

David P Bloomfield

Stephen A Perusich

John A Kosek

Anthony B La Conti

Cecelia C Cropley

Kelly D Barton

Olga Y Polevaya

James J Ferris

A gas diffusion backing for fuel cells wherein a porous carbonaceous paper or fabric, impregnated with a first fluorinated polymer, bears a microporous coating of a second fluorinated polymer admixed with carbon particles. Also, a process for making the composite wherein the fluorinated polymers are coalesced by heating above their glass transition temperature or melting point is described. A membrane electrode assembly prepared using these gas diffusion backing and a fuel are also provided.

Gas diffusion backing for fuel cells

An electrochemical cell system including an anode compartment and a cathode compartment separated by a membrane and electrode structure. This structure has an anode surface with a plurality of anodes in a side-by-side arrangement exposed to the anode compartment and a cathode surface with a plurality of cathodes in a side-by-side arrangement exposed to the cathode compartment. The anodes and cathodes are separated by a layer of ion exchange polymer and register with each other so that opposing pairs of anodes and cathodes form cells. The membrane and electrode structure further includes a plurality of current collector screens. The current collector screens have an anode contact area in contact with the anode, a cathode contact area in contact with the cathode and a feed through area extending between cells and crossing from the anode contact area to the cathode contact area to connect the anode and cathode of adjacent cells. The invention provides a polymer electrolyte membrane electrochemical cell system which can be less complicated, lighter in weight and/or is easier to manufacture that existing stack designs.

Electrochemical cell system with side-by-side arrangement of cells

A fuel cell and a battery with a reinforced polymeric ion exchange membrane are disclosed. The membrane comprises (a) a porous support layer, preferably of fluorine-containing polymer, and (b) an ion exchange resin, preferably a fluorinated ion exchange layer(s) supported on one or both sides of the porous support layer. The total thickness of the membrane is preferably from 20 to 500 .mu.m. The membrane has low fuel crossover, high electric conductivity and high mechanical strength. The membrane may especially be used in a direct methanol fuel cell.

Fuel cell incorporating a reinforced membrane

Cation exchange membranes incorporating a thin layer of polymer having having a high ratio of backbone carbon atoms to cation exchange groups provide improved performance in direct methanol fuel cells.

Membrane and electrode assembly employing exclusion membrane for direct

A method for making a composite fluorinated ion exchange membrane is provided comprising applying a continuous fluorinated ion exchange polymer film to a porous reinforcing substrate, preferably made from a polyolefin such as linear high density polyethylene. The composite membrane is made by applying a solvent to the surface of the film and/or the substrate and then affixing the reinforcing substrate. These reinforced membranes may advantageously be used as separators in fuel cells, and as selective barriers in permeation separation and facilitated transport operations.

Method for making reinforced ion exchange membranes

A membrane and electrode structure is formed by applying ink of catalytically active particles on the surface of the membrane. The electrode ink comprises:

Method of imprinting catalytically active particles on membrane

Ion exchange membranes or films are made from a solution of perfluorinated cycloalkanes, perfluorinated aromatic compounds and perfluorotrialkyl amines having a critical temperature greater than 150.degree. C. and certain carboxylic fluorinated polymers having an equivalent weight greater than 900. A process for repairing ion exchange membranes and films by spray coating the surface of the membrane or film with the solution is also claimed. The ion exchange membranes and films are useful in chloroalkali cells or fuel cells.

Process for making and repairing ion exchange membranes and films

The present invention is a process for modifying a fluorinated ion exchange membrane by irradiation of the membrane with a sufficient dose of non-spark-producing radiation to increase water absorption and/or ionic conductivity of the membrane. The membranes are particularly useful in fuel cells and chloralkali cells.

Irradiation of polymeric ion exchange membranes to increase water

The electrode layer of a ion exchange membrane is formed by printing a ink of catalytically active particles on the surface of the membrane. The inventive electrode ink comprises:

Membrane and electrode structure

A process is provided for hydrolysis of fluorinated ion exchange membranes. The membrane is contacted with an aqueous solution containing a hydrocarbon having ether, epoxy or ketone linkages and an alcohol group, preferably 1-methoxy 2-propanol, for a period of time sufficient to perform the hydrolysis of the precursor groups. The membrane is useful in a fuel cell or in an electrolytic cell, particularly a chloralkali cell.

Process for hydrolysis of ion exchange membranes

A diaphragm for electrolyzing alkali metal chloride solutions is provided which is one or more layers of a porous support, coated with a perfluoro ion exchange polymer and then wet with a wetting solution which has a surface tension of 22 to 45 dynes/cm. The wetting solution is preferably an aqueous alcohol and most preferably aqueous 3-6.5% butanol. The wetting solution assists in initial water penetration into the pores of the diaphragm, rendering the diaphragm hydrophilic so as to resist gas locking and premature shutdown of the electrolytic cell.

Wetting of diaphragms

Ion exchange membranes or films are made from a solution of perfluorinated cycloalkanes, perfluorinated aromatic compounds and perfluorotrialkyl amines having a critical temperature greater than 150.degree. C. and certain carboxylic fluorinated polymers having an equivalent weight greater than 900. A process for repairing ion exchange membranes and films by spray coating the surface of the membrane or film with the solution is also disclosed. The ion exchange membranes and films are useful in chloralkali cells or fuel cells.

Process for making ion exchange membranes and films

The present invention is a process for modifying a fluorinated cation exchange membrane by irradiation of the membrane in its salt form with a sufficient dose of non-spark-producing radiation to increase the current efficiency in the use of the membrane for electrolyzing sodium chloride solution to produce high concentrations of caustic.

Irradiation of cation exchange membranes to increse current efficiency

The present invention is a process for modifying a fluorinated cation exchange membrane by irradiation of the membrane with a sufficient dose of non-spark-producing radiation to decrease the voltage in the use of the membrane for electrolyzing brine.

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Newark, DE, United States of America

Shoibal Banerjee